File: | src/gnu/usr.bin/clang/libclangAST/../../../llvm/llvm/include/llvm/ADT/APSInt.h |
Warning: | line 22, column 22 Assigned value is garbage or undefined |
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1 | //===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // This file implements the Expr constant evaluator. |
10 | // |
11 | // Constant expression evaluation produces four main results: |
12 | // |
13 | // * A success/failure flag indicating whether constant folding was successful. |
14 | // This is the 'bool' return value used by most of the code in this file. A |
15 | // 'false' return value indicates that constant folding has failed, and any |
16 | // appropriate diagnostic has already been produced. |
17 | // |
18 | // * An evaluated result, valid only if constant folding has not failed. |
19 | // |
20 | // * A flag indicating if evaluation encountered (unevaluated) side-effects. |
21 | // These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1), |
22 | // where it is possible to determine the evaluated result regardless. |
23 | // |
24 | // * A set of notes indicating why the evaluation was not a constant expression |
25 | // (under the C++11 / C++1y rules only, at the moment), or, if folding failed |
26 | // too, why the expression could not be folded. |
27 | // |
28 | // If we are checking for a potential constant expression, failure to constant |
29 | // fold a potential constant sub-expression will be indicated by a 'false' |
30 | // return value (the expression could not be folded) and no diagnostic (the |
31 | // expression is not necessarily non-constant). |
32 | // |
33 | //===----------------------------------------------------------------------===// |
34 | |
35 | #include "Interp/Context.h" |
36 | #include "Interp/Frame.h" |
37 | #include "Interp/State.h" |
38 | #include "clang/AST/APValue.h" |
39 | #include "clang/AST/ASTContext.h" |
40 | #include "clang/AST/ASTDiagnostic.h" |
41 | #include "clang/AST/ASTLambda.h" |
42 | #include "clang/AST/Attr.h" |
43 | #include "clang/AST/CXXInheritance.h" |
44 | #include "clang/AST/CharUnits.h" |
45 | #include "clang/AST/CurrentSourceLocExprScope.h" |
46 | #include "clang/AST/Expr.h" |
47 | #include "clang/AST/OSLog.h" |
48 | #include "clang/AST/OptionalDiagnostic.h" |
49 | #include "clang/AST/RecordLayout.h" |
50 | #include "clang/AST/StmtVisitor.h" |
51 | #include "clang/AST/TypeLoc.h" |
52 | #include "clang/Basic/Builtins.h" |
53 | #include "clang/Basic/TargetInfo.h" |
54 | #include "llvm/ADT/APFixedPoint.h" |
55 | #include "llvm/ADT/Optional.h" |
56 | #include "llvm/ADT/SmallBitVector.h" |
57 | #include "llvm/Support/Debug.h" |
58 | #include "llvm/Support/SaveAndRestore.h" |
59 | #include "llvm/Support/raw_ostream.h" |
60 | #include <cstring> |
61 | #include <functional> |
62 | |
63 | #define DEBUG_TYPE"exprconstant" "exprconstant" |
64 | |
65 | using namespace clang; |
66 | using llvm::APFixedPoint; |
67 | using llvm::APInt; |
68 | using llvm::APSInt; |
69 | using llvm::APFloat; |
70 | using llvm::FixedPointSemantics; |
71 | using llvm::Optional; |
72 | |
73 | namespace { |
74 | struct LValue; |
75 | class CallStackFrame; |
76 | class EvalInfo; |
77 | |
78 | using SourceLocExprScopeGuard = |
79 | CurrentSourceLocExprScope::SourceLocExprScopeGuard; |
80 | |
81 | static QualType getType(APValue::LValueBase B) { |
82 | return B.getType(); |
83 | } |
84 | |
85 | /// Get an LValue path entry, which is known to not be an array index, as a |
86 | /// field declaration. |
87 | static const FieldDecl *getAsField(APValue::LValuePathEntry E) { |
88 | return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer()); |
89 | } |
90 | /// Get an LValue path entry, which is known to not be an array index, as a |
91 | /// base class declaration. |
92 | static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { |
93 | return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer()); |
94 | } |
95 | /// Determine whether this LValue path entry for a base class names a virtual |
96 | /// base class. |
97 | static bool isVirtualBaseClass(APValue::LValuePathEntry E) { |
98 | return E.getAsBaseOrMember().getInt(); |
99 | } |
100 | |
101 | /// Given an expression, determine the type used to store the result of |
102 | /// evaluating that expression. |
103 | static QualType getStorageType(const ASTContext &Ctx, const Expr *E) { |
104 | if (E->isPRValue()) |
105 | return E->getType(); |
106 | return Ctx.getLValueReferenceType(E->getType()); |
107 | } |
108 | |
109 | /// Given a CallExpr, try to get the alloc_size attribute. May return null. |
110 | static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) { |
111 | if (const FunctionDecl *DirectCallee = CE->getDirectCallee()) |
112 | return DirectCallee->getAttr<AllocSizeAttr>(); |
113 | if (const Decl *IndirectCallee = CE->getCalleeDecl()) |
114 | return IndirectCallee->getAttr<AllocSizeAttr>(); |
115 | return nullptr; |
116 | } |
117 | |
118 | /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr. |
119 | /// This will look through a single cast. |
120 | /// |
121 | /// Returns null if we couldn't unwrap a function with alloc_size. |
122 | static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) { |
123 | if (!E->getType()->isPointerType()) |
124 | return nullptr; |
125 | |
126 | E = E->IgnoreParens(); |
127 | // If we're doing a variable assignment from e.g. malloc(N), there will |
128 | // probably be a cast of some kind. In exotic cases, we might also see a |
129 | // top-level ExprWithCleanups. Ignore them either way. |
130 | if (const auto *FE = dyn_cast<FullExpr>(E)) |
131 | E = FE->getSubExpr()->IgnoreParens(); |
132 | |
133 | if (const auto *Cast = dyn_cast<CastExpr>(E)) |
134 | E = Cast->getSubExpr()->IgnoreParens(); |
135 | |
136 | if (const auto *CE = dyn_cast<CallExpr>(E)) |
137 | return getAllocSizeAttr(CE) ? CE : nullptr; |
138 | return nullptr; |
139 | } |
140 | |
141 | /// Determines whether or not the given Base contains a call to a function |
142 | /// with the alloc_size attribute. |
143 | static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) { |
144 | const auto *E = Base.dyn_cast<const Expr *>(); |
145 | return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E); |
146 | } |
147 | |
148 | /// Determines whether the given kind of constant expression is only ever |
149 | /// used for name mangling. If so, it's permitted to reference things that we |
150 | /// can't generate code for (in particular, dllimported functions). |
151 | static bool isForManglingOnly(ConstantExprKind Kind) { |
152 | switch (Kind) { |
153 | case ConstantExprKind::Normal: |
154 | case ConstantExprKind::ClassTemplateArgument: |
155 | case ConstantExprKind::ImmediateInvocation: |
156 | // Note that non-type template arguments of class type are emitted as |
157 | // template parameter objects. |
158 | return false; |
159 | |
160 | case ConstantExprKind::NonClassTemplateArgument: |
161 | return true; |
162 | } |
163 | llvm_unreachable("unknown ConstantExprKind")__builtin_unreachable(); |
164 | } |
165 | |
166 | static bool isTemplateArgument(ConstantExprKind Kind) { |
167 | switch (Kind) { |
168 | case ConstantExprKind::Normal: |
169 | case ConstantExprKind::ImmediateInvocation: |
170 | return false; |
171 | |
172 | case ConstantExprKind::ClassTemplateArgument: |
173 | case ConstantExprKind::NonClassTemplateArgument: |
174 | return true; |
175 | } |
176 | llvm_unreachable("unknown ConstantExprKind")__builtin_unreachable(); |
177 | } |
178 | |
179 | /// The bound to claim that an array of unknown bound has. |
180 | /// The value in MostDerivedArraySize is undefined in this case. So, set it |
181 | /// to an arbitrary value that's likely to loudly break things if it's used. |
182 | static const uint64_t AssumedSizeForUnsizedArray = |
183 | std::numeric_limits<uint64_t>::max() / 2; |
184 | |
185 | /// Determines if an LValue with the given LValueBase will have an unsized |
186 | /// array in its designator. |
187 | /// Find the path length and type of the most-derived subobject in the given |
188 | /// path, and find the size of the containing array, if any. |
189 | static unsigned |
190 | findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base, |
191 | ArrayRef<APValue::LValuePathEntry> Path, |
192 | uint64_t &ArraySize, QualType &Type, bool &IsArray, |
193 | bool &FirstEntryIsUnsizedArray) { |
194 | // This only accepts LValueBases from APValues, and APValues don't support |
195 | // arrays that lack size info. |
196 | assert(!isBaseAnAllocSizeCall(Base) &&((void)0) |
197 | "Unsized arrays shouldn't appear here")((void)0); |
198 | unsigned MostDerivedLength = 0; |
199 | Type = getType(Base); |
200 | |
201 | for (unsigned I = 0, N = Path.size(); I != N; ++I) { |
202 | if (Type->isArrayType()) { |
203 | const ArrayType *AT = Ctx.getAsArrayType(Type); |
204 | Type = AT->getElementType(); |
205 | MostDerivedLength = I + 1; |
206 | IsArray = true; |
207 | |
208 | if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) { |
209 | ArraySize = CAT->getSize().getZExtValue(); |
210 | } else { |
211 | assert(I == 0 && "unexpected unsized array designator")((void)0); |
212 | FirstEntryIsUnsizedArray = true; |
213 | ArraySize = AssumedSizeForUnsizedArray; |
214 | } |
215 | } else if (Type->isAnyComplexType()) { |
216 | const ComplexType *CT = Type->castAs<ComplexType>(); |
217 | Type = CT->getElementType(); |
218 | ArraySize = 2; |
219 | MostDerivedLength = I + 1; |
220 | IsArray = true; |
221 | } else if (const FieldDecl *FD = getAsField(Path[I])) { |
222 | Type = FD->getType(); |
223 | ArraySize = 0; |
224 | MostDerivedLength = I + 1; |
225 | IsArray = false; |
226 | } else { |
227 | // Path[I] describes a base class. |
228 | ArraySize = 0; |
229 | IsArray = false; |
230 | } |
231 | } |
232 | return MostDerivedLength; |
233 | } |
234 | |
235 | /// A path from a glvalue to a subobject of that glvalue. |
236 | struct SubobjectDesignator { |
237 | /// True if the subobject was named in a manner not supported by C++11. Such |
238 | /// lvalues can still be folded, but they are not core constant expressions |
239 | /// and we cannot perform lvalue-to-rvalue conversions on them. |
240 | unsigned Invalid : 1; |
241 | |
242 | /// Is this a pointer one past the end of an object? |
243 | unsigned IsOnePastTheEnd : 1; |
244 | |
245 | /// Indicator of whether the first entry is an unsized array. |
246 | unsigned FirstEntryIsAnUnsizedArray : 1; |
247 | |
248 | /// Indicator of whether the most-derived object is an array element. |
249 | unsigned MostDerivedIsArrayElement : 1; |
250 | |
251 | /// The length of the path to the most-derived object of which this is a |
252 | /// subobject. |
253 | unsigned MostDerivedPathLength : 28; |
254 | |
255 | /// The size of the array of which the most-derived object is an element. |
256 | /// This will always be 0 if the most-derived object is not an array |
257 | /// element. 0 is not an indicator of whether or not the most-derived object |
258 | /// is an array, however, because 0-length arrays are allowed. |
259 | /// |
260 | /// If the current array is an unsized array, the value of this is |
261 | /// undefined. |
262 | uint64_t MostDerivedArraySize; |
263 | |
264 | /// The type of the most derived object referred to by this address. |
265 | QualType MostDerivedType; |
266 | |
267 | typedef APValue::LValuePathEntry PathEntry; |
268 | |
269 | /// The entries on the path from the glvalue to the designated subobject. |
270 | SmallVector<PathEntry, 8> Entries; |
271 | |
272 | SubobjectDesignator() : Invalid(true) {} |
273 | |
274 | explicit SubobjectDesignator(QualType T) |
275 | : Invalid(false), IsOnePastTheEnd(false), |
276 | FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), |
277 | MostDerivedPathLength(0), MostDerivedArraySize(0), |
278 | MostDerivedType(T) {} |
279 | |
280 | SubobjectDesignator(ASTContext &Ctx, const APValue &V) |
281 | : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), |
282 | FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), |
283 | MostDerivedPathLength(0), MostDerivedArraySize(0) { |
284 | assert(V.isLValue() && "Non-LValue used to make an LValue designator?")((void)0); |
285 | if (!Invalid) { |
286 | IsOnePastTheEnd = V.isLValueOnePastTheEnd(); |
287 | ArrayRef<PathEntry> VEntries = V.getLValuePath(); |
288 | Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); |
289 | if (V.getLValueBase()) { |
290 | bool IsArray = false; |
291 | bool FirstIsUnsizedArray = false; |
292 | MostDerivedPathLength = findMostDerivedSubobject( |
293 | Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize, |
294 | MostDerivedType, IsArray, FirstIsUnsizedArray); |
295 | MostDerivedIsArrayElement = IsArray; |
296 | FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; |
297 | } |
298 | } |
299 | } |
300 | |
301 | void truncate(ASTContext &Ctx, APValue::LValueBase Base, |
302 | unsigned NewLength) { |
303 | if (Invalid) |
304 | return; |
305 | |
306 | assert(Base && "cannot truncate path for null pointer")((void)0); |
307 | assert(NewLength <= Entries.size() && "not a truncation")((void)0); |
308 | |
309 | if (NewLength == Entries.size()) |
310 | return; |
311 | Entries.resize(NewLength); |
312 | |
313 | bool IsArray = false; |
314 | bool FirstIsUnsizedArray = false; |
315 | MostDerivedPathLength = findMostDerivedSubobject( |
316 | Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray, |
317 | FirstIsUnsizedArray); |
318 | MostDerivedIsArrayElement = IsArray; |
319 | FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; |
320 | } |
321 | |
322 | void setInvalid() { |
323 | Invalid = true; |
324 | Entries.clear(); |
325 | } |
326 | |
327 | /// Determine whether the most derived subobject is an array without a |
328 | /// known bound. |
329 | bool isMostDerivedAnUnsizedArray() const { |
330 | assert(!Invalid && "Calling this makes no sense on invalid designators")((void)0); |
331 | return Entries.size() == 1 && FirstEntryIsAnUnsizedArray; |
332 | } |
333 | |
334 | /// Determine what the most derived array's size is. Results in an assertion |
335 | /// failure if the most derived array lacks a size. |
336 | uint64_t getMostDerivedArraySize() const { |
337 | assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size")((void)0); |
338 | return MostDerivedArraySize; |
339 | } |
340 | |
341 | /// Determine whether this is a one-past-the-end pointer. |
342 | bool isOnePastTheEnd() const { |
343 | assert(!Invalid)((void)0); |
344 | if (IsOnePastTheEnd) |
345 | return true; |
346 | if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement && |
347 | Entries[MostDerivedPathLength - 1].getAsArrayIndex() == |
348 | MostDerivedArraySize) |
349 | return true; |
350 | return false; |
351 | } |
352 | |
353 | /// Get the range of valid index adjustments in the form |
354 | /// {maximum value that can be subtracted from this pointer, |
355 | /// maximum value that can be added to this pointer} |
356 | std::pair<uint64_t, uint64_t> validIndexAdjustments() { |
357 | if (Invalid || isMostDerivedAnUnsizedArray()) |
358 | return {0, 0}; |
359 | |
360 | // [expr.add]p4: For the purposes of these operators, a pointer to a |
361 | // nonarray object behaves the same as a pointer to the first element of |
362 | // an array of length one with the type of the object as its element type. |
363 | bool IsArray = MostDerivedPathLength == Entries.size() && |
364 | MostDerivedIsArrayElement; |
365 | uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() |
366 | : (uint64_t)IsOnePastTheEnd; |
367 | uint64_t ArraySize = |
368 | IsArray ? getMostDerivedArraySize() : (uint64_t)1; |
369 | return {ArrayIndex, ArraySize - ArrayIndex}; |
370 | } |
371 | |
372 | /// Check that this refers to a valid subobject. |
373 | bool isValidSubobject() const { |
374 | if (Invalid) |
375 | return false; |
376 | return !isOnePastTheEnd(); |
377 | } |
378 | /// Check that this refers to a valid subobject, and if not, produce a |
379 | /// relevant diagnostic and set the designator as invalid. |
380 | bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); |
381 | |
382 | /// Get the type of the designated object. |
383 | QualType getType(ASTContext &Ctx) const { |
384 | assert(!Invalid && "invalid designator has no subobject type")((void)0); |
385 | return MostDerivedPathLength == Entries.size() |
386 | ? MostDerivedType |
387 | : Ctx.getRecordType(getAsBaseClass(Entries.back())); |
388 | } |
389 | |
390 | /// Update this designator to refer to the first element within this array. |
391 | void addArrayUnchecked(const ConstantArrayType *CAT) { |
392 | Entries.push_back(PathEntry::ArrayIndex(0)); |
393 | |
394 | // This is a most-derived object. |
395 | MostDerivedType = CAT->getElementType(); |
396 | MostDerivedIsArrayElement = true; |
397 | MostDerivedArraySize = CAT->getSize().getZExtValue(); |
398 | MostDerivedPathLength = Entries.size(); |
399 | } |
400 | /// Update this designator to refer to the first element within the array of |
401 | /// elements of type T. This is an array of unknown size. |
402 | void addUnsizedArrayUnchecked(QualType ElemTy) { |
403 | Entries.push_back(PathEntry::ArrayIndex(0)); |
404 | |
405 | MostDerivedType = ElemTy; |
406 | MostDerivedIsArrayElement = true; |
407 | // The value in MostDerivedArraySize is undefined in this case. So, set it |
408 | // to an arbitrary value that's likely to loudly break things if it's |
409 | // used. |
410 | MostDerivedArraySize = AssumedSizeForUnsizedArray; |
411 | MostDerivedPathLength = Entries.size(); |
412 | } |
413 | /// Update this designator to refer to the given base or member of this |
414 | /// object. |
415 | void addDeclUnchecked(const Decl *D, bool Virtual = false) { |
416 | Entries.push_back(APValue::BaseOrMemberType(D, Virtual)); |
417 | |
418 | // If this isn't a base class, it's a new most-derived object. |
419 | if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) { |
420 | MostDerivedType = FD->getType(); |
421 | MostDerivedIsArrayElement = false; |
422 | MostDerivedArraySize = 0; |
423 | MostDerivedPathLength = Entries.size(); |
424 | } |
425 | } |
426 | /// Update this designator to refer to the given complex component. |
427 | void addComplexUnchecked(QualType EltTy, bool Imag) { |
428 | Entries.push_back(PathEntry::ArrayIndex(Imag)); |
429 | |
430 | // This is technically a most-derived object, though in practice this |
431 | // is unlikely to matter. |
432 | MostDerivedType = EltTy; |
433 | MostDerivedIsArrayElement = true; |
434 | MostDerivedArraySize = 2; |
435 | MostDerivedPathLength = Entries.size(); |
436 | } |
437 | void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E); |
438 | void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, |
439 | const APSInt &N); |
440 | /// Add N to the address of this subobject. |
441 | void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) { |
442 | if (Invalid || !N) return; |
443 | uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue(); |
444 | if (isMostDerivedAnUnsizedArray()) { |
445 | diagnoseUnsizedArrayPointerArithmetic(Info, E); |
446 | // Can't verify -- trust that the user is doing the right thing (or if |
447 | // not, trust that the caller will catch the bad behavior). |
448 | // FIXME: Should we reject if this overflows, at least? |
449 | Entries.back() = PathEntry::ArrayIndex( |
450 | Entries.back().getAsArrayIndex() + TruncatedN); |
451 | return; |
452 | } |
453 | |
454 | // [expr.add]p4: For the purposes of these operators, a pointer to a |
455 | // nonarray object behaves the same as a pointer to the first element of |
456 | // an array of length one with the type of the object as its element type. |
457 | bool IsArray = MostDerivedPathLength == Entries.size() && |
458 | MostDerivedIsArrayElement; |
459 | uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() |
460 | : (uint64_t)IsOnePastTheEnd; |
461 | uint64_t ArraySize = |
462 | IsArray ? getMostDerivedArraySize() : (uint64_t)1; |
463 | |
464 | if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) { |
465 | // Calculate the actual index in a wide enough type, so we can include |
466 | // it in the note. |
467 | N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65)); |
468 | (llvm::APInt&)N += ArrayIndex; |
469 | assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index")((void)0); |
470 | diagnosePointerArithmetic(Info, E, N); |
471 | setInvalid(); |
472 | return; |
473 | } |
474 | |
475 | ArrayIndex += TruncatedN; |
476 | assert(ArrayIndex <= ArraySize &&((void)0) |
477 | "bounds check succeeded for out-of-bounds index")((void)0); |
478 | |
479 | if (IsArray) |
480 | Entries.back() = PathEntry::ArrayIndex(ArrayIndex); |
481 | else |
482 | IsOnePastTheEnd = (ArrayIndex != 0); |
483 | } |
484 | }; |
485 | |
486 | /// A scope at the end of which an object can need to be destroyed. |
487 | enum class ScopeKind { |
488 | Block, |
489 | FullExpression, |
490 | Call |
491 | }; |
492 | |
493 | /// A reference to a particular call and its arguments. |
494 | struct CallRef { |
495 | CallRef() : OrigCallee(), CallIndex(0), Version() {} |
496 | CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version) |
497 | : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {} |
498 | |
499 | explicit operator bool() const { return OrigCallee; } |
500 | |
501 | /// Get the parameter that the caller initialized, corresponding to the |
502 | /// given parameter in the callee. |
503 | const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const { |
504 | return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex()) |
505 | : PVD; |
506 | } |
507 | |
508 | /// The callee at the point where the arguments were evaluated. This might |
509 | /// be different from the actual callee (a different redeclaration, or a |
510 | /// virtual override), but this function's parameters are the ones that |
511 | /// appear in the parameter map. |
512 | const FunctionDecl *OrigCallee; |
513 | /// The call index of the frame that holds the argument values. |
514 | unsigned CallIndex; |
515 | /// The version of the parameters corresponding to this call. |
516 | unsigned Version; |
517 | }; |
518 | |
519 | /// A stack frame in the constexpr call stack. |
520 | class CallStackFrame : public interp::Frame { |
521 | public: |
522 | EvalInfo &Info; |
523 | |
524 | /// Parent - The caller of this stack frame. |
525 | CallStackFrame *Caller; |
526 | |
527 | /// Callee - The function which was called. |
528 | const FunctionDecl *Callee; |
529 | |
530 | /// This - The binding for the this pointer in this call, if any. |
531 | const LValue *This; |
532 | |
533 | /// Information on how to find the arguments to this call. Our arguments |
534 | /// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a |
535 | /// key and this value as the version. |
536 | CallRef Arguments; |
537 | |
538 | /// Source location information about the default argument or default |
539 | /// initializer expression we're evaluating, if any. |
540 | CurrentSourceLocExprScope CurSourceLocExprScope; |
541 | |
542 | // Note that we intentionally use std::map here so that references to |
543 | // values are stable. |
544 | typedef std::pair<const void *, unsigned> MapKeyTy; |
545 | typedef std::map<MapKeyTy, APValue> MapTy; |
546 | /// Temporaries - Temporary lvalues materialized within this stack frame. |
547 | MapTy Temporaries; |
548 | |
549 | /// CallLoc - The location of the call expression for this call. |
550 | SourceLocation CallLoc; |
551 | |
552 | /// Index - The call index of this call. |
553 | unsigned Index; |
554 | |
555 | /// The stack of integers for tracking version numbers for temporaries. |
556 | SmallVector<unsigned, 2> TempVersionStack = {1}; |
557 | unsigned CurTempVersion = TempVersionStack.back(); |
558 | |
559 | unsigned getTempVersion() const { return TempVersionStack.back(); } |
560 | |
561 | void pushTempVersion() { |
562 | TempVersionStack.push_back(++CurTempVersion); |
563 | } |
564 | |
565 | void popTempVersion() { |
566 | TempVersionStack.pop_back(); |
567 | } |
568 | |
569 | CallRef createCall(const FunctionDecl *Callee) { |
570 | return {Callee, Index, ++CurTempVersion}; |
571 | } |
572 | |
573 | // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact |
574 | // on the overall stack usage of deeply-recursing constexpr evaluations. |
575 | // (We should cache this map rather than recomputing it repeatedly.) |
576 | // But let's try this and see how it goes; we can look into caching the map |
577 | // as a later change. |
578 | |
579 | /// LambdaCaptureFields - Mapping from captured variables/this to |
580 | /// corresponding data members in the closure class. |
581 | llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields; |
582 | FieldDecl *LambdaThisCaptureField; |
583 | |
584 | CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, |
585 | const FunctionDecl *Callee, const LValue *This, |
586 | CallRef Arguments); |
587 | ~CallStackFrame(); |
588 | |
589 | // Return the temporary for Key whose version number is Version. |
590 | APValue *getTemporary(const void *Key, unsigned Version) { |
591 | MapKeyTy KV(Key, Version); |
592 | auto LB = Temporaries.lower_bound(KV); |
593 | if (LB != Temporaries.end() && LB->first == KV) |
594 | return &LB->second; |
595 | // Pair (Key,Version) wasn't found in the map. Check that no elements |
596 | // in the map have 'Key' as their key. |
597 | assert((LB == Temporaries.end() || LB->first.first != Key) &&((void)0) |
598 | (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&((void)0) |
599 | "Element with key 'Key' found in map")((void)0); |
600 | return nullptr; |
601 | } |
602 | |
603 | // Return the current temporary for Key in the map. |
604 | APValue *getCurrentTemporary(const void *Key) { |
605 | auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U))); |
606 | if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) |
607 | return &std::prev(UB)->second; |
608 | return nullptr; |
609 | } |
610 | |
611 | // Return the version number of the current temporary for Key. |
612 | unsigned getCurrentTemporaryVersion(const void *Key) const { |
613 | auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U))); |
614 | if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) |
615 | return std::prev(UB)->first.second; |
616 | return 0; |
617 | } |
618 | |
619 | /// Allocate storage for an object of type T in this stack frame. |
620 | /// Populates LV with a handle to the created object. Key identifies |
621 | /// the temporary within the stack frame, and must not be reused without |
622 | /// bumping the temporary version number. |
623 | template<typename KeyT> |
624 | APValue &createTemporary(const KeyT *Key, QualType T, |
625 | ScopeKind Scope, LValue &LV); |
626 | |
627 | /// Allocate storage for a parameter of a function call made in this frame. |
628 | APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV); |
629 | |
630 | void describe(llvm::raw_ostream &OS) override; |
631 | |
632 | Frame *getCaller() const override { return Caller; } |
633 | SourceLocation getCallLocation() const override { return CallLoc; } |
634 | const FunctionDecl *getCallee() const override { return Callee; } |
635 | |
636 | bool isStdFunction() const { |
637 | for (const DeclContext *DC = Callee; DC; DC = DC->getParent()) |
638 | if (DC->isStdNamespace()) |
639 | return true; |
640 | return false; |
641 | } |
642 | |
643 | private: |
644 | APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T, |
645 | ScopeKind Scope); |
646 | }; |
647 | |
648 | /// Temporarily override 'this'. |
649 | class ThisOverrideRAII { |
650 | public: |
651 | ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable) |
652 | : Frame(Frame), OldThis(Frame.This) { |
653 | if (Enable) |
654 | Frame.This = NewThis; |
655 | } |
656 | ~ThisOverrideRAII() { |
657 | Frame.This = OldThis; |
658 | } |
659 | private: |
660 | CallStackFrame &Frame; |
661 | const LValue *OldThis; |
662 | }; |
663 | } |
664 | |
665 | static bool HandleDestruction(EvalInfo &Info, const Expr *E, |
666 | const LValue &This, QualType ThisType); |
667 | static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc, |
668 | APValue::LValueBase LVBase, APValue &Value, |
669 | QualType T); |
670 | |
671 | namespace { |
672 | /// A cleanup, and a flag indicating whether it is lifetime-extended. |
673 | class Cleanup { |
674 | llvm::PointerIntPair<APValue*, 2, ScopeKind> Value; |
675 | APValue::LValueBase Base; |
676 | QualType T; |
677 | |
678 | public: |
679 | Cleanup(APValue *Val, APValue::LValueBase Base, QualType T, |
680 | ScopeKind Scope) |
681 | : Value(Val, Scope), Base(Base), T(T) {} |
682 | |
683 | /// Determine whether this cleanup should be performed at the end of the |
684 | /// given kind of scope. |
685 | bool isDestroyedAtEndOf(ScopeKind K) const { |
686 | return (int)Value.getInt() >= (int)K; |
687 | } |
688 | bool endLifetime(EvalInfo &Info, bool RunDestructors) { |
689 | if (RunDestructors) { |
690 | SourceLocation Loc; |
691 | if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) |
692 | Loc = VD->getLocation(); |
693 | else if (const Expr *E = Base.dyn_cast<const Expr*>()) |
694 | Loc = E->getExprLoc(); |
695 | return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T); |
696 | } |
697 | *Value.getPointer() = APValue(); |
698 | return true; |
699 | } |
700 | |
701 | bool hasSideEffect() { |
702 | return T.isDestructedType(); |
703 | } |
704 | }; |
705 | |
706 | /// A reference to an object whose construction we are currently evaluating. |
707 | struct ObjectUnderConstruction { |
708 | APValue::LValueBase Base; |
709 | ArrayRef<APValue::LValuePathEntry> Path; |
710 | friend bool operator==(const ObjectUnderConstruction &LHS, |
711 | const ObjectUnderConstruction &RHS) { |
712 | return LHS.Base == RHS.Base && LHS.Path == RHS.Path; |
713 | } |
714 | friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) { |
715 | return llvm::hash_combine(Obj.Base, Obj.Path); |
716 | } |
717 | }; |
718 | enum class ConstructionPhase { |
719 | None, |
720 | Bases, |
721 | AfterBases, |
722 | AfterFields, |
723 | Destroying, |
724 | DestroyingBases |
725 | }; |
726 | } |
727 | |
728 | namespace llvm { |
729 | template<> struct DenseMapInfo<ObjectUnderConstruction> { |
730 | using Base = DenseMapInfo<APValue::LValueBase>; |
731 | static ObjectUnderConstruction getEmptyKey() { |
732 | return {Base::getEmptyKey(), {}}; } |
733 | static ObjectUnderConstruction getTombstoneKey() { |
734 | return {Base::getTombstoneKey(), {}}; |
735 | } |
736 | static unsigned getHashValue(const ObjectUnderConstruction &Object) { |
737 | return hash_value(Object); |
738 | } |
739 | static bool isEqual(const ObjectUnderConstruction &LHS, |
740 | const ObjectUnderConstruction &RHS) { |
741 | return LHS == RHS; |
742 | } |
743 | }; |
744 | } |
745 | |
746 | namespace { |
747 | /// A dynamically-allocated heap object. |
748 | struct DynAlloc { |
749 | /// The value of this heap-allocated object. |
750 | APValue Value; |
751 | /// The allocating expression; used for diagnostics. Either a CXXNewExpr |
752 | /// or a CallExpr (the latter is for direct calls to operator new inside |
753 | /// std::allocator<T>::allocate). |
754 | const Expr *AllocExpr = nullptr; |
755 | |
756 | enum Kind { |
757 | New, |
758 | ArrayNew, |
759 | StdAllocator |
760 | }; |
761 | |
762 | /// Get the kind of the allocation. This must match between allocation |
763 | /// and deallocation. |
764 | Kind getKind() const { |
765 | if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr)) |
766 | return NE->isArray() ? ArrayNew : New; |
767 | assert(isa<CallExpr>(AllocExpr))((void)0); |
768 | return StdAllocator; |
769 | } |
770 | }; |
771 | |
772 | struct DynAllocOrder { |
773 | bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const { |
774 | return L.getIndex() < R.getIndex(); |
775 | } |
776 | }; |
777 | |
778 | /// EvalInfo - This is a private struct used by the evaluator to capture |
779 | /// information about a subexpression as it is folded. It retains information |
780 | /// about the AST context, but also maintains information about the folded |
781 | /// expression. |
782 | /// |
783 | /// If an expression could be evaluated, it is still possible it is not a C |
784 | /// "integer constant expression" or constant expression. If not, this struct |
785 | /// captures information about how and why not. |
786 | /// |
787 | /// One bit of information passed *into* the request for constant folding |
788 | /// indicates whether the subexpression is "evaluated" or not according to C |
789 | /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can |
790 | /// evaluate the expression regardless of what the RHS is, but C only allows |
791 | /// certain things in certain situations. |
792 | class EvalInfo : public interp::State { |
793 | public: |
794 | ASTContext &Ctx; |
795 | |
796 | /// EvalStatus - Contains information about the evaluation. |
797 | Expr::EvalStatus &EvalStatus; |
798 | |
799 | /// CurrentCall - The top of the constexpr call stack. |
800 | CallStackFrame *CurrentCall; |
801 | |
802 | /// CallStackDepth - The number of calls in the call stack right now. |
803 | unsigned CallStackDepth; |
804 | |
805 | /// NextCallIndex - The next call index to assign. |
806 | unsigned NextCallIndex; |
807 | |
808 | /// StepsLeft - The remaining number of evaluation steps we're permitted |
809 | /// to perform. This is essentially a limit for the number of statements |
810 | /// we will evaluate. |
811 | unsigned StepsLeft; |
812 | |
813 | /// Enable the experimental new constant interpreter. If an expression is |
814 | /// not supported by the interpreter, an error is triggered. |
815 | bool EnableNewConstInterp; |
816 | |
817 | /// BottomFrame - The frame in which evaluation started. This must be |
818 | /// initialized after CurrentCall and CallStackDepth. |
819 | CallStackFrame BottomFrame; |
820 | |
821 | /// A stack of values whose lifetimes end at the end of some surrounding |
822 | /// evaluation frame. |
823 | llvm::SmallVector<Cleanup, 16> CleanupStack; |
824 | |
825 | /// EvaluatingDecl - This is the declaration whose initializer is being |
826 | /// evaluated, if any. |
827 | APValue::LValueBase EvaluatingDecl; |
828 | |
829 | enum class EvaluatingDeclKind { |
830 | None, |
831 | /// We're evaluating the construction of EvaluatingDecl. |
832 | Ctor, |
833 | /// We're evaluating the destruction of EvaluatingDecl. |
834 | Dtor, |
835 | }; |
836 | EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None; |
837 | |
838 | /// EvaluatingDeclValue - This is the value being constructed for the |
839 | /// declaration whose initializer is being evaluated, if any. |
840 | APValue *EvaluatingDeclValue; |
841 | |
842 | /// Set of objects that are currently being constructed. |
843 | llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase> |
844 | ObjectsUnderConstruction; |
845 | |
846 | /// Current heap allocations, along with the location where each was |
847 | /// allocated. We use std::map here because we need stable addresses |
848 | /// for the stored APValues. |
849 | std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs; |
850 | |
851 | /// The number of heap allocations performed so far in this evaluation. |
852 | unsigned NumHeapAllocs = 0; |
853 | |
854 | struct EvaluatingConstructorRAII { |
855 | EvalInfo &EI; |
856 | ObjectUnderConstruction Object; |
857 | bool DidInsert; |
858 | EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object, |
859 | bool HasBases) |
860 | : EI(EI), Object(Object) { |
861 | DidInsert = |
862 | EI.ObjectsUnderConstruction |
863 | .insert({Object, HasBases ? ConstructionPhase::Bases |
864 | : ConstructionPhase::AfterBases}) |
865 | .second; |
866 | } |
867 | void finishedConstructingBases() { |
868 | EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases; |
869 | } |
870 | void finishedConstructingFields() { |
871 | EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields; |
872 | } |
873 | ~EvaluatingConstructorRAII() { |
874 | if (DidInsert) EI.ObjectsUnderConstruction.erase(Object); |
875 | } |
876 | }; |
877 | |
878 | struct EvaluatingDestructorRAII { |
879 | EvalInfo &EI; |
880 | ObjectUnderConstruction Object; |
881 | bool DidInsert; |
882 | EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object) |
883 | : EI(EI), Object(Object) { |
884 | DidInsert = EI.ObjectsUnderConstruction |
885 | .insert({Object, ConstructionPhase::Destroying}) |
886 | .second; |
887 | } |
888 | void startedDestroyingBases() { |
889 | EI.ObjectsUnderConstruction[Object] = |
890 | ConstructionPhase::DestroyingBases; |
891 | } |
892 | ~EvaluatingDestructorRAII() { |
893 | if (DidInsert) |
894 | EI.ObjectsUnderConstruction.erase(Object); |
895 | } |
896 | }; |
897 | |
898 | ConstructionPhase |
899 | isEvaluatingCtorDtor(APValue::LValueBase Base, |
900 | ArrayRef<APValue::LValuePathEntry> Path) { |
901 | return ObjectsUnderConstruction.lookup({Base, Path}); |
902 | } |
903 | |
904 | /// If we're currently speculatively evaluating, the outermost call stack |
905 | /// depth at which we can mutate state, otherwise 0. |
906 | unsigned SpeculativeEvaluationDepth = 0; |
907 | |
908 | /// The current array initialization index, if we're performing array |
909 | /// initialization. |
910 | uint64_t ArrayInitIndex = -1; |
911 | |
912 | /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further |
913 | /// notes attached to it will also be stored, otherwise they will not be. |
914 | bool HasActiveDiagnostic; |
915 | |
916 | /// Have we emitted a diagnostic explaining why we couldn't constant |
917 | /// fold (not just why it's not strictly a constant expression)? |
918 | bool HasFoldFailureDiagnostic; |
919 | |
920 | /// Whether or not we're in a context where the front end requires a |
921 | /// constant value. |
922 | bool InConstantContext; |
923 | |
924 | /// Whether we're checking that an expression is a potential constant |
925 | /// expression. If so, do not fail on constructs that could become constant |
926 | /// later on (such as a use of an undefined global). |
927 | bool CheckingPotentialConstantExpression = false; |
928 | |
929 | /// Whether we're checking for an expression that has undefined behavior. |
930 | /// If so, we will produce warnings if we encounter an operation that is |
931 | /// always undefined. |
932 | /// |
933 | /// Note that we still need to evaluate the expression normally when this |
934 | /// is set; this is used when evaluating ICEs in C. |
935 | bool CheckingForUndefinedBehavior = false; |
936 | |
937 | enum EvaluationMode { |
938 | /// Evaluate as a constant expression. Stop if we find that the expression |
939 | /// is not a constant expression. |
940 | EM_ConstantExpression, |
941 | |
942 | /// Evaluate as a constant expression. Stop if we find that the expression |
943 | /// is not a constant expression. Some expressions can be retried in the |
944 | /// optimizer if we don't constant fold them here, but in an unevaluated |
945 | /// context we try to fold them immediately since the optimizer never |
946 | /// gets a chance to look at it. |
947 | EM_ConstantExpressionUnevaluated, |
948 | |
949 | /// Fold the expression to a constant. Stop if we hit a side-effect that |
950 | /// we can't model. |
951 | EM_ConstantFold, |
952 | |
953 | /// Evaluate in any way we know how. Don't worry about side-effects that |
954 | /// can't be modeled. |
955 | EM_IgnoreSideEffects, |
956 | } EvalMode; |
957 | |
958 | /// Are we checking whether the expression is a potential constant |
959 | /// expression? |
960 | bool checkingPotentialConstantExpression() const override { |
961 | return CheckingPotentialConstantExpression; |
962 | } |
963 | |
964 | /// Are we checking an expression for overflow? |
965 | // FIXME: We should check for any kind of undefined or suspicious behavior |
966 | // in such constructs, not just overflow. |
967 | bool checkingForUndefinedBehavior() const override { |
968 | return CheckingForUndefinedBehavior; |
969 | } |
970 | |
971 | EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) |
972 | : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr), |
973 | CallStackDepth(0), NextCallIndex(1), |
974 | StepsLeft(C.getLangOpts().ConstexprStepLimit), |
975 | EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp), |
976 | BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()), |
977 | EvaluatingDecl((const ValueDecl *)nullptr), |
978 | EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), |
979 | HasFoldFailureDiagnostic(false), InConstantContext(false), |
980 | EvalMode(Mode) {} |
981 | |
982 | ~EvalInfo() { |
983 | discardCleanups(); |
984 | } |
985 | |
986 | void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value, |
987 | EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) { |
988 | EvaluatingDecl = Base; |
989 | IsEvaluatingDecl = EDK; |
990 | EvaluatingDeclValue = &Value; |
991 | } |
992 | |
993 | bool CheckCallLimit(SourceLocation Loc) { |
994 | // Don't perform any constexpr calls (other than the call we're checking) |
995 | // when checking a potential constant expression. |
996 | if (checkingPotentialConstantExpression() && CallStackDepth > 1) |
997 | return false; |
998 | if (NextCallIndex == 0) { |
999 | // NextCallIndex has wrapped around. |
1000 | FFDiag(Loc, diag::note_constexpr_call_limit_exceeded); |
1001 | return false; |
1002 | } |
1003 | if (CallStackDepth <= getLangOpts().ConstexprCallDepth) |
1004 | return true; |
1005 | FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded) |
1006 | << getLangOpts().ConstexprCallDepth; |
1007 | return false; |
1008 | } |
1009 | |
1010 | std::pair<CallStackFrame *, unsigned> |
1011 | getCallFrameAndDepth(unsigned CallIndex) { |
1012 | assert(CallIndex && "no call index in getCallFrameAndDepth")((void)0); |
1013 | // We will eventually hit BottomFrame, which has Index 1, so Frame can't |
1014 | // be null in this loop. |
1015 | unsigned Depth = CallStackDepth; |
1016 | CallStackFrame *Frame = CurrentCall; |
1017 | while (Frame->Index > CallIndex) { |
1018 | Frame = Frame->Caller; |
1019 | --Depth; |
1020 | } |
1021 | if (Frame->Index == CallIndex) |
1022 | return {Frame, Depth}; |
1023 | return {nullptr, 0}; |
1024 | } |
1025 | |
1026 | bool nextStep(const Stmt *S) { |
1027 | if (!StepsLeft) { |
1028 | FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded); |
1029 | return false; |
1030 | } |
1031 | --StepsLeft; |
1032 | return true; |
1033 | } |
1034 | |
1035 | APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV); |
1036 | |
1037 | Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) { |
1038 | Optional<DynAlloc*> Result; |
1039 | auto It = HeapAllocs.find(DA); |
1040 | if (It != HeapAllocs.end()) |
1041 | Result = &It->second; |
1042 | return Result; |
1043 | } |
1044 | |
1045 | /// Get the allocated storage for the given parameter of the given call. |
1046 | APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) { |
1047 | CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first; |
1048 | return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version) |
1049 | : nullptr; |
1050 | } |
1051 | |
1052 | /// Information about a stack frame for std::allocator<T>::[de]allocate. |
1053 | struct StdAllocatorCaller { |
1054 | unsigned FrameIndex; |
1055 | QualType ElemType; |
1056 | explicit operator bool() const { return FrameIndex != 0; }; |
1057 | }; |
1058 | |
1059 | StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const { |
1060 | for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame; |
1061 | Call = Call->Caller) { |
1062 | const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee); |
1063 | if (!MD) |
1064 | continue; |
1065 | const IdentifierInfo *FnII = MD->getIdentifier(); |
1066 | if (!FnII || !FnII->isStr(FnName)) |
1067 | continue; |
1068 | |
1069 | const auto *CTSD = |
1070 | dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent()); |
1071 | if (!CTSD) |
1072 | continue; |
1073 | |
1074 | const IdentifierInfo *ClassII = CTSD->getIdentifier(); |
1075 | const TemplateArgumentList &TAL = CTSD->getTemplateArgs(); |
1076 | if (CTSD->isInStdNamespace() && ClassII && |
1077 | ClassII->isStr("allocator") && TAL.size() >= 1 && |
1078 | TAL[0].getKind() == TemplateArgument::Type) |
1079 | return {Call->Index, TAL[0].getAsType()}; |
1080 | } |
1081 | |
1082 | return {}; |
1083 | } |
1084 | |
1085 | void performLifetimeExtension() { |
1086 | // Disable the cleanups for lifetime-extended temporaries. |
1087 | CleanupStack.erase(std::remove_if(CleanupStack.begin(), |
1088 | CleanupStack.end(), |
1089 | [](Cleanup &C) { |
1090 | return !C.isDestroyedAtEndOf( |
1091 | ScopeKind::FullExpression); |
1092 | }), |
1093 | CleanupStack.end()); |
1094 | } |
1095 | |
1096 | /// Throw away any remaining cleanups at the end of evaluation. If any |
1097 | /// cleanups would have had a side-effect, note that as an unmodeled |
1098 | /// side-effect and return false. Otherwise, return true. |
1099 | bool discardCleanups() { |
1100 | for (Cleanup &C : CleanupStack) { |
1101 | if (C.hasSideEffect() && !noteSideEffect()) { |
1102 | CleanupStack.clear(); |
1103 | return false; |
1104 | } |
1105 | } |
1106 | CleanupStack.clear(); |
1107 | return true; |
1108 | } |
1109 | |
1110 | private: |
1111 | interp::Frame *getCurrentFrame() override { return CurrentCall; } |
1112 | const interp::Frame *getBottomFrame() const override { return &BottomFrame; } |
1113 | |
1114 | bool hasActiveDiagnostic() override { return HasActiveDiagnostic; } |
1115 | void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; } |
1116 | |
1117 | void setFoldFailureDiagnostic(bool Flag) override { |
1118 | HasFoldFailureDiagnostic = Flag; |
1119 | } |
1120 | |
1121 | Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; } |
1122 | |
1123 | ASTContext &getCtx() const override { return Ctx; } |
1124 | |
1125 | // If we have a prior diagnostic, it will be noting that the expression |
1126 | // isn't a constant expression. This diagnostic is more important, |
1127 | // unless we require this evaluation to produce a constant expression. |
1128 | // |
1129 | // FIXME: We might want to show both diagnostics to the user in |
1130 | // EM_ConstantFold mode. |
1131 | bool hasPriorDiagnostic() override { |
1132 | if (!EvalStatus.Diag->empty()) { |
1133 | switch (EvalMode) { |
1134 | case EM_ConstantFold: |
1135 | case EM_IgnoreSideEffects: |
1136 | if (!HasFoldFailureDiagnostic) |
1137 | break; |
1138 | // We've already failed to fold something. Keep that diagnostic. |
1139 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; |
1140 | case EM_ConstantExpression: |
1141 | case EM_ConstantExpressionUnevaluated: |
1142 | setActiveDiagnostic(false); |
1143 | return true; |
1144 | } |
1145 | } |
1146 | return false; |
1147 | } |
1148 | |
1149 | unsigned getCallStackDepth() override { return CallStackDepth; } |
1150 | |
1151 | public: |
1152 | /// Should we continue evaluation after encountering a side-effect that we |
1153 | /// couldn't model? |
1154 | bool keepEvaluatingAfterSideEffect() { |
1155 | switch (EvalMode) { |
1156 | case EM_IgnoreSideEffects: |
1157 | return true; |
1158 | |
1159 | case EM_ConstantExpression: |
1160 | case EM_ConstantExpressionUnevaluated: |
1161 | case EM_ConstantFold: |
1162 | // By default, assume any side effect might be valid in some other |
1163 | // evaluation of this expression from a different context. |
1164 | return checkingPotentialConstantExpression() || |
1165 | checkingForUndefinedBehavior(); |
1166 | } |
1167 | llvm_unreachable("Missed EvalMode case")__builtin_unreachable(); |
1168 | } |
1169 | |
1170 | /// Note that we have had a side-effect, and determine whether we should |
1171 | /// keep evaluating. |
1172 | bool noteSideEffect() { |
1173 | EvalStatus.HasSideEffects = true; |
1174 | return keepEvaluatingAfterSideEffect(); |
1175 | } |
1176 | |
1177 | /// Should we continue evaluation after encountering undefined behavior? |
1178 | bool keepEvaluatingAfterUndefinedBehavior() { |
1179 | switch (EvalMode) { |
1180 | case EM_IgnoreSideEffects: |
1181 | case EM_ConstantFold: |
1182 | return true; |
1183 | |
1184 | case EM_ConstantExpression: |
1185 | case EM_ConstantExpressionUnevaluated: |
1186 | return checkingForUndefinedBehavior(); |
1187 | } |
1188 | llvm_unreachable("Missed EvalMode case")__builtin_unreachable(); |
1189 | } |
1190 | |
1191 | /// Note that we hit something that was technically undefined behavior, but |
1192 | /// that we can evaluate past it (such as signed overflow or floating-point |
1193 | /// division by zero.) |
1194 | bool noteUndefinedBehavior() override { |
1195 | EvalStatus.HasUndefinedBehavior = true; |
1196 | return keepEvaluatingAfterUndefinedBehavior(); |
1197 | } |
1198 | |
1199 | /// Should we continue evaluation as much as possible after encountering a |
1200 | /// construct which can't be reduced to a value? |
1201 | bool keepEvaluatingAfterFailure() const override { |
1202 | if (!StepsLeft) |
1203 | return false; |
1204 | |
1205 | switch (EvalMode) { |
1206 | case EM_ConstantExpression: |
1207 | case EM_ConstantExpressionUnevaluated: |
1208 | case EM_ConstantFold: |
1209 | case EM_IgnoreSideEffects: |
1210 | return checkingPotentialConstantExpression() || |
1211 | checkingForUndefinedBehavior(); |
1212 | } |
1213 | llvm_unreachable("Missed EvalMode case")__builtin_unreachable(); |
1214 | } |
1215 | |
1216 | /// Notes that we failed to evaluate an expression that other expressions |
1217 | /// directly depend on, and determine if we should keep evaluating. This |
1218 | /// should only be called if we actually intend to keep evaluating. |
1219 | /// |
1220 | /// Call noteSideEffect() instead if we may be able to ignore the value that |
1221 | /// we failed to evaluate, e.g. if we failed to evaluate Foo() in: |
1222 | /// |
1223 | /// (Foo(), 1) // use noteSideEffect |
1224 | /// (Foo() || true) // use noteSideEffect |
1225 | /// Foo() + 1 // use noteFailure |
1226 | LLVM_NODISCARD[[clang::warn_unused_result]] bool noteFailure() { |
1227 | // Failure when evaluating some expression often means there is some |
1228 | // subexpression whose evaluation was skipped. Therefore, (because we |
1229 | // don't track whether we skipped an expression when unwinding after an |
1230 | // evaluation failure) every evaluation failure that bubbles up from a |
1231 | // subexpression implies that a side-effect has potentially happened. We |
1232 | // skip setting the HasSideEffects flag to true until we decide to |
1233 | // continue evaluating after that point, which happens here. |
1234 | bool KeepGoing = keepEvaluatingAfterFailure(); |
1235 | EvalStatus.HasSideEffects |= KeepGoing; |
1236 | return KeepGoing; |
1237 | } |
1238 | |
1239 | class ArrayInitLoopIndex { |
1240 | EvalInfo &Info; |
1241 | uint64_t OuterIndex; |
1242 | |
1243 | public: |
1244 | ArrayInitLoopIndex(EvalInfo &Info) |
1245 | : Info(Info), OuterIndex(Info.ArrayInitIndex) { |
1246 | Info.ArrayInitIndex = 0; |
1247 | } |
1248 | ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; } |
1249 | |
1250 | operator uint64_t&() { return Info.ArrayInitIndex; } |
1251 | }; |
1252 | }; |
1253 | |
1254 | /// Object used to treat all foldable expressions as constant expressions. |
1255 | struct FoldConstant { |
1256 | EvalInfo &Info; |
1257 | bool Enabled; |
1258 | bool HadNoPriorDiags; |
1259 | EvalInfo::EvaluationMode OldMode; |
1260 | |
1261 | explicit FoldConstant(EvalInfo &Info, bool Enabled) |
1262 | : Info(Info), |
1263 | Enabled(Enabled), |
1264 | HadNoPriorDiags(Info.EvalStatus.Diag && |
1265 | Info.EvalStatus.Diag->empty() && |
1266 | !Info.EvalStatus.HasSideEffects), |
1267 | OldMode(Info.EvalMode) { |
1268 | if (Enabled) |
1269 | Info.EvalMode = EvalInfo::EM_ConstantFold; |
1270 | } |
1271 | void keepDiagnostics() { Enabled = false; } |
1272 | ~FoldConstant() { |
1273 | if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && |
1274 | !Info.EvalStatus.HasSideEffects) |
1275 | Info.EvalStatus.Diag->clear(); |
1276 | Info.EvalMode = OldMode; |
1277 | } |
1278 | }; |
1279 | |
1280 | /// RAII object used to set the current evaluation mode to ignore |
1281 | /// side-effects. |
1282 | struct IgnoreSideEffectsRAII { |
1283 | EvalInfo &Info; |
1284 | EvalInfo::EvaluationMode OldMode; |
1285 | explicit IgnoreSideEffectsRAII(EvalInfo &Info) |
1286 | : Info(Info), OldMode(Info.EvalMode) { |
1287 | Info.EvalMode = EvalInfo::EM_IgnoreSideEffects; |
1288 | } |
1289 | |
1290 | ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; } |
1291 | }; |
1292 | |
1293 | /// RAII object used to optionally suppress diagnostics and side-effects from |
1294 | /// a speculative evaluation. |
1295 | class SpeculativeEvaluationRAII { |
1296 | EvalInfo *Info = nullptr; |
1297 | Expr::EvalStatus OldStatus; |
1298 | unsigned OldSpeculativeEvaluationDepth; |
1299 | |
1300 | void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) { |
1301 | Info = Other.Info; |
1302 | OldStatus = Other.OldStatus; |
1303 | OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth; |
1304 | Other.Info = nullptr; |
1305 | } |
1306 | |
1307 | void maybeRestoreState() { |
1308 | if (!Info) |
1309 | return; |
1310 | |
1311 | Info->EvalStatus = OldStatus; |
1312 | Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth; |
1313 | } |
1314 | |
1315 | public: |
1316 | SpeculativeEvaluationRAII() = default; |
1317 | |
1318 | SpeculativeEvaluationRAII( |
1319 | EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr) |
1320 | : Info(&Info), OldStatus(Info.EvalStatus), |
1321 | OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) { |
1322 | Info.EvalStatus.Diag = NewDiag; |
1323 | Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1; |
1324 | } |
1325 | |
1326 | SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete; |
1327 | SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) { |
1328 | moveFromAndCancel(std::move(Other)); |
1329 | } |
1330 | |
1331 | SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) { |
1332 | maybeRestoreState(); |
1333 | moveFromAndCancel(std::move(Other)); |
1334 | return *this; |
1335 | } |
1336 | |
1337 | ~SpeculativeEvaluationRAII() { maybeRestoreState(); } |
1338 | }; |
1339 | |
1340 | /// RAII object wrapping a full-expression or block scope, and handling |
1341 | /// the ending of the lifetime of temporaries created within it. |
1342 | template<ScopeKind Kind> |
1343 | class ScopeRAII { |
1344 | EvalInfo &Info; |
1345 | unsigned OldStackSize; |
1346 | public: |
1347 | ScopeRAII(EvalInfo &Info) |
1348 | : Info(Info), OldStackSize(Info.CleanupStack.size()) { |
1349 | // Push a new temporary version. This is needed to distinguish between |
1350 | // temporaries created in different iterations of a loop. |
1351 | Info.CurrentCall->pushTempVersion(); |
1352 | } |
1353 | bool destroy(bool RunDestructors = true) { |
1354 | bool OK = cleanup(Info, RunDestructors, OldStackSize); |
1355 | OldStackSize = -1U; |
1356 | return OK; |
1357 | } |
1358 | ~ScopeRAII() { |
1359 | if (OldStackSize != -1U) |
1360 | destroy(false); |
1361 | // Body moved to a static method to encourage the compiler to inline away |
1362 | // instances of this class. |
1363 | Info.CurrentCall->popTempVersion(); |
1364 | } |
1365 | private: |
1366 | static bool cleanup(EvalInfo &Info, bool RunDestructors, |
1367 | unsigned OldStackSize) { |
1368 | assert(OldStackSize <= Info.CleanupStack.size() &&((void)0) |
1369 | "running cleanups out of order?")((void)0); |
1370 | |
1371 | // Run all cleanups for a block scope, and non-lifetime-extended cleanups |
1372 | // for a full-expression scope. |
1373 | bool Success = true; |
1374 | for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) { |
1375 | if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) { |
1376 | if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) { |
1377 | Success = false; |
1378 | break; |
1379 | } |
1380 | } |
1381 | } |
1382 | |
1383 | // Compact any retained cleanups. |
1384 | auto NewEnd = Info.CleanupStack.begin() + OldStackSize; |
1385 | if (Kind != ScopeKind::Block) |
1386 | NewEnd = |
1387 | std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) { |
1388 | return C.isDestroyedAtEndOf(Kind); |
1389 | }); |
1390 | Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end()); |
1391 | return Success; |
1392 | } |
1393 | }; |
1394 | typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII; |
1395 | typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII; |
1396 | typedef ScopeRAII<ScopeKind::Call> CallScopeRAII; |
1397 | } |
1398 | |
1399 | bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, |
1400 | CheckSubobjectKind CSK) { |
1401 | if (Invalid) |
1402 | return false; |
1403 | if (isOnePastTheEnd()) { |
1404 | Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) |
1405 | << CSK; |
1406 | setInvalid(); |
1407 | return false; |
1408 | } |
1409 | // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there |
1410 | // must actually be at least one array element; even a VLA cannot have a |
1411 | // bound of zero. And if our index is nonzero, we already had a CCEDiag. |
1412 | return true; |
1413 | } |
1414 | |
1415 | void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, |
1416 | const Expr *E) { |
1417 | Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed); |
1418 | // Do not set the designator as invalid: we can represent this situation, |
1419 | // and correct handling of __builtin_object_size requires us to do so. |
1420 | } |
1421 | |
1422 | void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, |
1423 | const Expr *E, |
1424 | const APSInt &N) { |
1425 | // If we're complaining, we must be able to statically determine the size of |
1426 | // the most derived array. |
1427 | if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement) |
1428 | Info.CCEDiag(E, diag::note_constexpr_array_index) |
1429 | << N << /*array*/ 0 |
1430 | << static_cast<unsigned>(getMostDerivedArraySize()); |
1431 | else |
1432 | Info.CCEDiag(E, diag::note_constexpr_array_index) |
1433 | << N << /*non-array*/ 1; |
1434 | setInvalid(); |
1435 | } |
1436 | |
1437 | CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, |
1438 | const FunctionDecl *Callee, const LValue *This, |
1439 | CallRef Call) |
1440 | : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This), |
1441 | Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) { |
1442 | Info.CurrentCall = this; |
1443 | ++Info.CallStackDepth; |
1444 | } |
1445 | |
1446 | CallStackFrame::~CallStackFrame() { |
1447 | assert(Info.CurrentCall == this && "calls retired out of order")((void)0); |
1448 | --Info.CallStackDepth; |
1449 | Info.CurrentCall = Caller; |
1450 | } |
1451 | |
1452 | static bool isRead(AccessKinds AK) { |
1453 | return AK == AK_Read || AK == AK_ReadObjectRepresentation; |
1454 | } |
1455 | |
1456 | static bool isModification(AccessKinds AK) { |
1457 | switch (AK) { |
1458 | case AK_Read: |
1459 | case AK_ReadObjectRepresentation: |
1460 | case AK_MemberCall: |
1461 | case AK_DynamicCast: |
1462 | case AK_TypeId: |
1463 | return false; |
1464 | case AK_Assign: |
1465 | case AK_Increment: |
1466 | case AK_Decrement: |
1467 | case AK_Construct: |
1468 | case AK_Destroy: |
1469 | return true; |
1470 | } |
1471 | llvm_unreachable("unknown access kind")__builtin_unreachable(); |
1472 | } |
1473 | |
1474 | static bool isAnyAccess(AccessKinds AK) { |
1475 | return isRead(AK) || isModification(AK); |
1476 | } |
1477 | |
1478 | /// Is this an access per the C++ definition? |
1479 | static bool isFormalAccess(AccessKinds AK) { |
1480 | return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy; |
1481 | } |
1482 | |
1483 | /// Is this kind of axcess valid on an indeterminate object value? |
1484 | static bool isValidIndeterminateAccess(AccessKinds AK) { |
1485 | switch (AK) { |
1486 | case AK_Read: |
1487 | case AK_Increment: |
1488 | case AK_Decrement: |
1489 | // These need the object's value. |
1490 | return false; |
1491 | |
1492 | case AK_ReadObjectRepresentation: |
1493 | case AK_Assign: |
1494 | case AK_Construct: |
1495 | case AK_Destroy: |
1496 | // Construction and destruction don't need the value. |
1497 | return true; |
1498 | |
1499 | case AK_MemberCall: |
1500 | case AK_DynamicCast: |
1501 | case AK_TypeId: |
1502 | // These aren't really meaningful on scalars. |
1503 | return true; |
1504 | } |
1505 | llvm_unreachable("unknown access kind")__builtin_unreachable(); |
1506 | } |
1507 | |
1508 | namespace { |
1509 | struct ComplexValue { |
1510 | private: |
1511 | bool IsInt; |
1512 | |
1513 | public: |
1514 | APSInt IntReal, IntImag; |
1515 | APFloat FloatReal, FloatImag; |
1516 | |
1517 | ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {} |
1518 | |
1519 | void makeComplexFloat() { IsInt = false; } |
1520 | bool isComplexFloat() const { return !IsInt; } |
1521 | APFloat &getComplexFloatReal() { return FloatReal; } |
1522 | APFloat &getComplexFloatImag() { return FloatImag; } |
1523 | |
1524 | void makeComplexInt() { IsInt = true; } |
1525 | bool isComplexInt() const { return IsInt; } |
1526 | APSInt &getComplexIntReal() { return IntReal; } |
1527 | APSInt &getComplexIntImag() { return IntImag; } |
1528 | |
1529 | void moveInto(APValue &v) const { |
1530 | if (isComplexFloat()) |
1531 | v = APValue(FloatReal, FloatImag); |
1532 | else |
1533 | v = APValue(IntReal, IntImag); |
1534 | } |
1535 | void setFrom(const APValue &v) { |
1536 | assert(v.isComplexFloat() || v.isComplexInt())((void)0); |
1537 | if (v.isComplexFloat()) { |
1538 | makeComplexFloat(); |
1539 | FloatReal = v.getComplexFloatReal(); |
1540 | FloatImag = v.getComplexFloatImag(); |
1541 | } else { |
1542 | makeComplexInt(); |
1543 | IntReal = v.getComplexIntReal(); |
1544 | IntImag = v.getComplexIntImag(); |
1545 | } |
1546 | } |
1547 | }; |
1548 | |
1549 | struct LValue { |
1550 | APValue::LValueBase Base; |
1551 | CharUnits Offset; |
1552 | SubobjectDesignator Designator; |
1553 | bool IsNullPtr : 1; |
1554 | bool InvalidBase : 1; |
1555 | |
1556 | const APValue::LValueBase getLValueBase() const { return Base; } |
1557 | CharUnits &getLValueOffset() { return Offset; } |
1558 | const CharUnits &getLValueOffset() const { return Offset; } |
1559 | SubobjectDesignator &getLValueDesignator() { return Designator; } |
1560 | const SubobjectDesignator &getLValueDesignator() const { return Designator;} |
1561 | bool isNullPointer() const { return IsNullPtr;} |
1562 | |
1563 | unsigned getLValueCallIndex() const { return Base.getCallIndex(); } |
1564 | unsigned getLValueVersion() const { return Base.getVersion(); } |
1565 | |
1566 | void moveInto(APValue &V) const { |
1567 | if (Designator.Invalid) |
1568 | V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr); |
1569 | else { |
1570 | assert(!InvalidBase && "APValues can't handle invalid LValue bases")((void)0); |
1571 | V = APValue(Base, Offset, Designator.Entries, |
1572 | Designator.IsOnePastTheEnd, IsNullPtr); |
1573 | } |
1574 | } |
1575 | void setFrom(ASTContext &Ctx, const APValue &V) { |
1576 | assert(V.isLValue() && "Setting LValue from a non-LValue?")((void)0); |
1577 | Base = V.getLValueBase(); |
1578 | Offset = V.getLValueOffset(); |
1579 | InvalidBase = false; |
1580 | Designator = SubobjectDesignator(Ctx, V); |
1581 | IsNullPtr = V.isNullPointer(); |
1582 | } |
1583 | |
1584 | void set(APValue::LValueBase B, bool BInvalid = false) { |
1585 | #ifndef NDEBUG1 |
1586 | // We only allow a few types of invalid bases. Enforce that here. |
1587 | if (BInvalid) { |
1588 | const auto *E = B.get<const Expr *>(); |
1589 | assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&((void)0) |
1590 | "Unexpected type of invalid base")((void)0); |
1591 | } |
1592 | #endif |
1593 | |
1594 | Base = B; |
1595 | Offset = CharUnits::fromQuantity(0); |
1596 | InvalidBase = BInvalid; |
1597 | Designator = SubobjectDesignator(getType(B)); |
1598 | IsNullPtr = false; |
1599 | } |
1600 | |
1601 | void setNull(ASTContext &Ctx, QualType PointerTy) { |
1602 | Base = (const ValueDecl *)nullptr; |
1603 | Offset = |
1604 | CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy)); |
1605 | InvalidBase = false; |
1606 | Designator = SubobjectDesignator(PointerTy->getPointeeType()); |
1607 | IsNullPtr = true; |
1608 | } |
1609 | |
1610 | void setInvalid(APValue::LValueBase B, unsigned I = 0) { |
1611 | set(B, true); |
1612 | } |
1613 | |
1614 | std::string toString(ASTContext &Ctx, QualType T) const { |
1615 | APValue Printable; |
1616 | moveInto(Printable); |
1617 | return Printable.getAsString(Ctx, T); |
1618 | } |
1619 | |
1620 | private: |
1621 | // Check that this LValue is not based on a null pointer. If it is, produce |
1622 | // a diagnostic and mark the designator as invalid. |
1623 | template <typename GenDiagType> |
1624 | bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) { |
1625 | if (Designator.Invalid) |
1626 | return false; |
1627 | if (IsNullPtr) { |
1628 | GenDiag(); |
1629 | Designator.setInvalid(); |
1630 | return false; |
1631 | } |
1632 | return true; |
1633 | } |
1634 | |
1635 | public: |
1636 | bool checkNullPointer(EvalInfo &Info, const Expr *E, |
1637 | CheckSubobjectKind CSK) { |
1638 | return checkNullPointerDiagnosingWith([&Info, E, CSK] { |
1639 | Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK; |
1640 | }); |
1641 | } |
1642 | |
1643 | bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E, |
1644 | AccessKinds AK) { |
1645 | return checkNullPointerDiagnosingWith([&Info, E, AK] { |
1646 | Info.FFDiag(E, diag::note_constexpr_access_null) << AK; |
1647 | }); |
1648 | } |
1649 | |
1650 | // Check this LValue refers to an object. If not, set the designator to be |
1651 | // invalid and emit a diagnostic. |
1652 | bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { |
1653 | return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && |
1654 | Designator.checkSubobject(Info, E, CSK); |
1655 | } |
1656 | |
1657 | void addDecl(EvalInfo &Info, const Expr *E, |
1658 | const Decl *D, bool Virtual = false) { |
1659 | if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) |
1660 | Designator.addDeclUnchecked(D, Virtual); |
1661 | } |
1662 | void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) { |
1663 | if (!Designator.Entries.empty()) { |
1664 | Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array); |
1665 | Designator.setInvalid(); |
1666 | return; |
1667 | } |
1668 | if (checkSubobject(Info, E, CSK_ArrayToPointer)) { |
1669 | assert(getType(Base)->isPointerType() || getType(Base)->isArrayType())((void)0); |
1670 | Designator.FirstEntryIsAnUnsizedArray = true; |
1671 | Designator.addUnsizedArrayUnchecked(ElemTy); |
1672 | } |
1673 | } |
1674 | void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { |
1675 | if (checkSubobject(Info, E, CSK_ArrayToPointer)) |
1676 | Designator.addArrayUnchecked(CAT); |
1677 | } |
1678 | void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { |
1679 | if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) |
1680 | Designator.addComplexUnchecked(EltTy, Imag); |
1681 | } |
1682 | void clearIsNullPointer() { |
1683 | IsNullPtr = false; |
1684 | } |
1685 | void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E, |
1686 | const APSInt &Index, CharUnits ElementSize) { |
1687 | // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB, |
1688 | // but we're not required to diagnose it and it's valid in C++.) |
1689 | if (!Index) |
1690 | return; |
1691 | |
1692 | // Compute the new offset in the appropriate width, wrapping at 64 bits. |
1693 | // FIXME: When compiling for a 32-bit target, we should use 32-bit |
1694 | // offsets. |
1695 | uint64_t Offset64 = Offset.getQuantity(); |
1696 | uint64_t ElemSize64 = ElementSize.getQuantity(); |
1697 | uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); |
1698 | Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64); |
1699 | |
1700 | if (checkNullPointer(Info, E, CSK_ArrayIndex)) |
1701 | Designator.adjustIndex(Info, E, Index); |
1702 | clearIsNullPointer(); |
1703 | } |
1704 | void adjustOffset(CharUnits N) { |
1705 | Offset += N; |
1706 | if (N.getQuantity()) |
1707 | clearIsNullPointer(); |
1708 | } |
1709 | }; |
1710 | |
1711 | struct MemberPtr { |
1712 | MemberPtr() {} |
1713 | explicit MemberPtr(const ValueDecl *Decl) : |
1714 | DeclAndIsDerivedMember(Decl, false), Path() {} |
1715 | |
1716 | /// The member or (direct or indirect) field referred to by this member |
1717 | /// pointer, or 0 if this is a null member pointer. |
1718 | const ValueDecl *getDecl() const { |
1719 | return DeclAndIsDerivedMember.getPointer(); |
1720 | } |
1721 | /// Is this actually a member of some type derived from the relevant class? |
1722 | bool isDerivedMember() const { |
1723 | return DeclAndIsDerivedMember.getInt(); |
1724 | } |
1725 | /// Get the class which the declaration actually lives in. |
1726 | const CXXRecordDecl *getContainingRecord() const { |
1727 | return cast<CXXRecordDecl>( |
1728 | DeclAndIsDerivedMember.getPointer()->getDeclContext()); |
1729 | } |
1730 | |
1731 | void moveInto(APValue &V) const { |
1732 | V = APValue(getDecl(), isDerivedMember(), Path); |
1733 | } |
1734 | void setFrom(const APValue &V) { |
1735 | assert(V.isMemberPointer())((void)0); |
1736 | DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); |
1737 | DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); |
1738 | Path.clear(); |
1739 | ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); |
1740 | Path.insert(Path.end(), P.begin(), P.end()); |
1741 | } |
1742 | |
1743 | /// DeclAndIsDerivedMember - The member declaration, and a flag indicating |
1744 | /// whether the member is a member of some class derived from the class type |
1745 | /// of the member pointer. |
1746 | llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; |
1747 | /// Path - The path of base/derived classes from the member declaration's |
1748 | /// class (exclusive) to the class type of the member pointer (inclusive). |
1749 | SmallVector<const CXXRecordDecl*, 4> Path; |
1750 | |
1751 | /// Perform a cast towards the class of the Decl (either up or down the |
1752 | /// hierarchy). |
1753 | bool castBack(const CXXRecordDecl *Class) { |
1754 | assert(!Path.empty())((void)0); |
1755 | const CXXRecordDecl *Expected; |
1756 | if (Path.size() >= 2) |
1757 | Expected = Path[Path.size() - 2]; |
1758 | else |
1759 | Expected = getContainingRecord(); |
1760 | if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { |
1761 | // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), |
1762 | // if B does not contain the original member and is not a base or |
1763 | // derived class of the class containing the original member, the result |
1764 | // of the cast is undefined. |
1765 | // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to |
1766 | // (D::*). We consider that to be a language defect. |
1767 | return false; |
1768 | } |
1769 | Path.pop_back(); |
1770 | return true; |
1771 | } |
1772 | /// Perform a base-to-derived member pointer cast. |
1773 | bool castToDerived(const CXXRecordDecl *Derived) { |
1774 | if (!getDecl()) |
1775 | return true; |
1776 | if (!isDerivedMember()) { |
1777 | Path.push_back(Derived); |
1778 | return true; |
1779 | } |
1780 | if (!castBack(Derived)) |
1781 | return false; |
1782 | if (Path.empty()) |
1783 | DeclAndIsDerivedMember.setInt(false); |
1784 | return true; |
1785 | } |
1786 | /// Perform a derived-to-base member pointer cast. |
1787 | bool castToBase(const CXXRecordDecl *Base) { |
1788 | if (!getDecl()) |
1789 | return true; |
1790 | if (Path.empty()) |
1791 | DeclAndIsDerivedMember.setInt(true); |
1792 | if (isDerivedMember()) { |
1793 | Path.push_back(Base); |
1794 | return true; |
1795 | } |
1796 | return castBack(Base); |
1797 | } |
1798 | }; |
1799 | |
1800 | /// Compare two member pointers, which are assumed to be of the same type. |
1801 | static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { |
1802 | if (!LHS.getDecl() || !RHS.getDecl()) |
1803 | return !LHS.getDecl() && !RHS.getDecl(); |
1804 | if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) |
1805 | return false; |
1806 | return LHS.Path == RHS.Path; |
1807 | } |
1808 | } |
1809 | |
1810 | static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); |
1811 | static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, |
1812 | const LValue &This, const Expr *E, |
1813 | bool AllowNonLiteralTypes = false); |
1814 | static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, |
1815 | bool InvalidBaseOK = false); |
1816 | static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info, |
1817 | bool InvalidBaseOK = false); |
1818 | static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, |
1819 | EvalInfo &Info); |
1820 | static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); |
1821 | static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); |
1822 | static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, |
1823 | EvalInfo &Info); |
1824 | static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); |
1825 | static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); |
1826 | static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, |
1827 | EvalInfo &Info); |
1828 | static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result); |
1829 | |
1830 | /// Evaluate an integer or fixed point expression into an APResult. |
1831 | static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, |
1832 | EvalInfo &Info); |
1833 | |
1834 | /// Evaluate only a fixed point expression into an APResult. |
1835 | static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, |
1836 | EvalInfo &Info); |
1837 | |
1838 | //===----------------------------------------------------------------------===// |
1839 | // Misc utilities |
1840 | //===----------------------------------------------------------------------===// |
1841 | |
1842 | /// Negate an APSInt in place, converting it to a signed form if necessary, and |
1843 | /// preserving its value (by extending by up to one bit as needed). |
1844 | static void negateAsSigned(APSInt &Int) { |
1845 | if (Int.isUnsigned() || Int.isMinSignedValue()) { |
1846 | Int = Int.extend(Int.getBitWidth() + 1); |
1847 | Int.setIsSigned(true); |
1848 | } |
1849 | Int = -Int; |
1850 | } |
1851 | |
1852 | template<typename KeyT> |
1853 | APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T, |
1854 | ScopeKind Scope, LValue &LV) { |
1855 | unsigned Version = getTempVersion(); |
1856 | APValue::LValueBase Base(Key, Index, Version); |
1857 | LV.set(Base); |
1858 | return createLocal(Base, Key, T, Scope); |
1859 | } |
1860 | |
1861 | /// Allocate storage for a parameter of a function call made in this frame. |
1862 | APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD, |
1863 | LValue &LV) { |
1864 | assert(Args.CallIndex == Index && "creating parameter in wrong frame")((void)0); |
1865 | APValue::LValueBase Base(PVD, Index, Args.Version); |
1866 | LV.set(Base); |
1867 | // We always destroy parameters at the end of the call, even if we'd allow |
1868 | // them to live to the end of the full-expression at runtime, in order to |
1869 | // give portable results and match other compilers. |
1870 | return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call); |
1871 | } |
1872 | |
1873 | APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key, |
1874 | QualType T, ScopeKind Scope) { |
1875 | assert(Base.getCallIndex() == Index && "lvalue for wrong frame")((void)0); |
1876 | unsigned Version = Base.getVersion(); |
1877 | APValue &Result = Temporaries[MapKeyTy(Key, Version)]; |
1878 | assert(Result.isAbsent() && "local created multiple times")((void)0); |
1879 | |
1880 | // If we're creating a local immediately in the operand of a speculative |
1881 | // evaluation, don't register a cleanup to be run outside the speculative |
1882 | // evaluation context, since we won't actually be able to initialize this |
1883 | // object. |
1884 | if (Index <= Info.SpeculativeEvaluationDepth) { |
1885 | if (T.isDestructedType()) |
1886 | Info.noteSideEffect(); |
1887 | } else { |
1888 | Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope)); |
1889 | } |
1890 | return Result; |
1891 | } |
1892 | |
1893 | APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) { |
1894 | if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) { |
1895 | FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded); |
1896 | return nullptr; |
1897 | } |
1898 | |
1899 | DynamicAllocLValue DA(NumHeapAllocs++); |
1900 | LV.set(APValue::LValueBase::getDynamicAlloc(DA, T)); |
1901 | auto Result = HeapAllocs.emplace(std::piecewise_construct, |
1902 | std::forward_as_tuple(DA), std::tuple<>()); |
1903 | assert(Result.second && "reused a heap alloc index?")((void)0); |
1904 | Result.first->second.AllocExpr = E; |
1905 | return &Result.first->second.Value; |
1906 | } |
1907 | |
1908 | /// Produce a string describing the given constexpr call. |
1909 | void CallStackFrame::describe(raw_ostream &Out) { |
1910 | unsigned ArgIndex = 0; |
1911 | bool IsMemberCall = isa<CXXMethodDecl>(Callee) && |
1912 | !isa<CXXConstructorDecl>(Callee) && |
1913 | cast<CXXMethodDecl>(Callee)->isInstance(); |
1914 | |
1915 | if (!IsMemberCall) |
1916 | Out << *Callee << '('; |
1917 | |
1918 | if (This && IsMemberCall) { |
1919 | APValue Val; |
1920 | This->moveInto(Val); |
1921 | Val.printPretty(Out, Info.Ctx, |
1922 | This->Designator.MostDerivedType); |
1923 | // FIXME: Add parens around Val if needed. |
1924 | Out << "->" << *Callee << '('; |
1925 | IsMemberCall = false; |
1926 | } |
1927 | |
1928 | for (FunctionDecl::param_const_iterator I = Callee->param_begin(), |
1929 | E = Callee->param_end(); I != E; ++I, ++ArgIndex) { |
1930 | if (ArgIndex > (unsigned)IsMemberCall) |
1931 | Out << ", "; |
1932 | |
1933 | const ParmVarDecl *Param = *I; |
1934 | APValue *V = Info.getParamSlot(Arguments, Param); |
1935 | if (V) |
1936 | V->printPretty(Out, Info.Ctx, Param->getType()); |
1937 | else |
1938 | Out << "<...>"; |
1939 | |
1940 | if (ArgIndex == 0 && IsMemberCall) |
1941 | Out << "->" << *Callee << '('; |
1942 | } |
1943 | |
1944 | Out << ')'; |
1945 | } |
1946 | |
1947 | /// Evaluate an expression to see if it had side-effects, and discard its |
1948 | /// result. |
1949 | /// \return \c true if the caller should keep evaluating. |
1950 | static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { |
1951 | assert(!E->isValueDependent())((void)0); |
1952 | APValue Scratch; |
1953 | if (!Evaluate(Scratch, Info, E)) |
1954 | // We don't need the value, but we might have skipped a side effect here. |
1955 | return Info.noteSideEffect(); |
1956 | return true; |
1957 | } |
1958 | |
1959 | /// Should this call expression be treated as a string literal? |
1960 | static bool IsStringLiteralCall(const CallExpr *E) { |
1961 | unsigned Builtin = E->getBuiltinCallee(); |
1962 | return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || |
1963 | Builtin == Builtin::BI__builtin___NSStringMakeConstantString); |
1964 | } |
1965 | |
1966 | static bool IsGlobalLValue(APValue::LValueBase B) { |
1967 | // C++11 [expr.const]p3 An address constant expression is a prvalue core |
1968 | // constant expression of pointer type that evaluates to... |
1969 | |
1970 | // ... a null pointer value, or a prvalue core constant expression of type |
1971 | // std::nullptr_t. |
1972 | if (!B) return true; |
1973 | |
1974 | if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { |
1975 | // ... the address of an object with static storage duration, |
1976 | if (const VarDecl *VD = dyn_cast<VarDecl>(D)) |
1977 | return VD->hasGlobalStorage(); |
1978 | if (isa<TemplateParamObjectDecl>(D)) |
1979 | return true; |
1980 | // ... the address of a function, |
1981 | // ... the address of a GUID [MS extension], |
1982 | return isa<FunctionDecl>(D) || isa<MSGuidDecl>(D); |
1983 | } |
1984 | |
1985 | if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>()) |
1986 | return true; |
1987 | |
1988 | const Expr *E = B.get<const Expr*>(); |
1989 | switch (E->getStmtClass()) { |
1990 | default: |
1991 | return false; |
1992 | case Expr::CompoundLiteralExprClass: { |
1993 | const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); |
1994 | return CLE->isFileScope() && CLE->isLValue(); |
1995 | } |
1996 | case Expr::MaterializeTemporaryExprClass: |
1997 | // A materialized temporary might have been lifetime-extended to static |
1998 | // storage duration. |
1999 | return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static; |
2000 | // A string literal has static storage duration. |
2001 | case Expr::StringLiteralClass: |
2002 | case Expr::PredefinedExprClass: |
2003 | case Expr::ObjCStringLiteralClass: |
2004 | case Expr::ObjCEncodeExprClass: |
2005 | return true; |
2006 | case Expr::ObjCBoxedExprClass: |
2007 | return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer(); |
2008 | case Expr::CallExprClass: |
2009 | return IsStringLiteralCall(cast<CallExpr>(E)); |
2010 | // For GCC compatibility, &&label has static storage duration. |
2011 | case Expr::AddrLabelExprClass: |
2012 | return true; |
2013 | // A Block literal expression may be used as the initialization value for |
2014 | // Block variables at global or local static scope. |
2015 | case Expr::BlockExprClass: |
2016 | return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); |
2017 | case Expr::ImplicitValueInitExprClass: |
2018 | // FIXME: |
2019 | // We can never form an lvalue with an implicit value initialization as its |
2020 | // base through expression evaluation, so these only appear in one case: the |
2021 | // implicit variable declaration we invent when checking whether a constexpr |
2022 | // constructor can produce a constant expression. We must assume that such |
2023 | // an expression might be a global lvalue. |
2024 | return true; |
2025 | } |
2026 | } |
2027 | |
2028 | static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { |
2029 | return LVal.Base.dyn_cast<const ValueDecl*>(); |
2030 | } |
2031 | |
2032 | static bool IsLiteralLValue(const LValue &Value) { |
2033 | if (Value.getLValueCallIndex()) |
2034 | return false; |
2035 | const Expr *E = Value.Base.dyn_cast<const Expr*>(); |
2036 | return E && !isa<MaterializeTemporaryExpr>(E); |
2037 | } |
2038 | |
2039 | static bool IsWeakLValue(const LValue &Value) { |
2040 | const ValueDecl *Decl = GetLValueBaseDecl(Value); |
2041 | return Decl && Decl->isWeak(); |
2042 | } |
2043 | |
2044 | static bool isZeroSized(const LValue &Value) { |
2045 | const ValueDecl *Decl = GetLValueBaseDecl(Value); |
2046 | if (Decl && isa<VarDecl>(Decl)) { |
2047 | QualType Ty = Decl->getType(); |
2048 | if (Ty->isArrayType()) |
2049 | return Ty->isIncompleteType() || |
2050 | Decl->getASTContext().getTypeSize(Ty) == 0; |
2051 | } |
2052 | return false; |
2053 | } |
2054 | |
2055 | static bool HasSameBase(const LValue &A, const LValue &B) { |
2056 | if (!A.getLValueBase()) |
2057 | return !B.getLValueBase(); |
2058 | if (!B.getLValueBase()) |
2059 | return false; |
2060 | |
2061 | if (A.getLValueBase().getOpaqueValue() != |
2062 | B.getLValueBase().getOpaqueValue()) |
2063 | return false; |
2064 | |
2065 | return A.getLValueCallIndex() == B.getLValueCallIndex() && |
2066 | A.getLValueVersion() == B.getLValueVersion(); |
2067 | } |
2068 | |
2069 | static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { |
2070 | assert(Base && "no location for a null lvalue")((void)0); |
2071 | const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); |
2072 | |
2073 | // For a parameter, find the corresponding call stack frame (if it still |
2074 | // exists), and point at the parameter of the function definition we actually |
2075 | // invoked. |
2076 | if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) { |
2077 | unsigned Idx = PVD->getFunctionScopeIndex(); |
2078 | for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) { |
2079 | if (F->Arguments.CallIndex == Base.getCallIndex() && |
2080 | F->Arguments.Version == Base.getVersion() && F->Callee && |
2081 | Idx < F->Callee->getNumParams()) { |
2082 | VD = F->Callee->getParamDecl(Idx); |
2083 | break; |
2084 | } |
2085 | } |
2086 | } |
2087 | |
2088 | if (VD) |
2089 | Info.Note(VD->getLocation(), diag::note_declared_at); |
2090 | else if (const Expr *E = Base.dyn_cast<const Expr*>()) |
2091 | Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here); |
2092 | else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) { |
2093 | // FIXME: Produce a note for dangling pointers too. |
2094 | if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA)) |
2095 | Info.Note((*Alloc)->AllocExpr->getExprLoc(), |
2096 | diag::note_constexpr_dynamic_alloc_here); |
2097 | } |
2098 | // We have no information to show for a typeid(T) object. |
2099 | } |
2100 | |
2101 | enum class CheckEvaluationResultKind { |
2102 | ConstantExpression, |
2103 | FullyInitialized, |
2104 | }; |
2105 | |
2106 | /// Materialized temporaries that we've already checked to determine if they're |
2107 | /// initializsed by a constant expression. |
2108 | using CheckedTemporaries = |
2109 | llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>; |
2110 | |
2111 | static bool CheckEvaluationResult(CheckEvaluationResultKind CERK, |
2112 | EvalInfo &Info, SourceLocation DiagLoc, |
2113 | QualType Type, const APValue &Value, |
2114 | ConstantExprKind Kind, |
2115 | SourceLocation SubobjectLoc, |
2116 | CheckedTemporaries &CheckedTemps); |
2117 | |
2118 | /// Check that this reference or pointer core constant expression is a valid |
2119 | /// value for an address or reference constant expression. Return true if we |
2120 | /// can fold this expression, whether or not it's a constant expression. |
2121 | static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, |
2122 | QualType Type, const LValue &LVal, |
2123 | ConstantExprKind Kind, |
2124 | CheckedTemporaries &CheckedTemps) { |
2125 | bool IsReferenceType = Type->isReferenceType(); |
2126 | |
2127 | APValue::LValueBase Base = LVal.getLValueBase(); |
2128 | const SubobjectDesignator &Designator = LVal.getLValueDesignator(); |
2129 | |
2130 | const Expr *BaseE = Base.dyn_cast<const Expr *>(); |
2131 | const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>(); |
2132 | |
2133 | // Additional restrictions apply in a template argument. We only enforce the |
2134 | // C++20 restrictions here; additional syntactic and semantic restrictions |
2135 | // are applied elsewhere. |
2136 | if (isTemplateArgument(Kind)) { |
2137 | int InvalidBaseKind = -1; |
2138 | StringRef Ident; |
2139 | if (Base.is<TypeInfoLValue>()) |
2140 | InvalidBaseKind = 0; |
2141 | else if (isa_and_nonnull<StringLiteral>(BaseE)) |
2142 | InvalidBaseKind = 1; |
2143 | else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) || |
2144 | isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD)) |
2145 | InvalidBaseKind = 2; |
2146 | else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) { |
2147 | InvalidBaseKind = 3; |
2148 | Ident = PE->getIdentKindName(); |
2149 | } |
2150 | |
2151 | if (InvalidBaseKind != -1) { |
2152 | Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg) |
2153 | << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind |
2154 | << Ident; |
2155 | return false; |
2156 | } |
2157 | } |
2158 | |
2159 | if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) { |
2160 | if (FD->isConsteval()) { |
2161 | Info.FFDiag(Loc, diag::note_consteval_address_accessible) |
2162 | << !Type->isAnyPointerType(); |
2163 | Info.Note(FD->getLocation(), diag::note_declared_at); |
2164 | return false; |
2165 | } |
2166 | } |
2167 | |
2168 | // Check that the object is a global. Note that the fake 'this' object we |
2169 | // manufacture when checking potential constant expressions is conservatively |
2170 | // assumed to be global here. |
2171 | if (!IsGlobalLValue(Base)) { |
2172 | if (Info.getLangOpts().CPlusPlus11) { |
2173 | const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); |
2174 | Info.FFDiag(Loc, diag::note_constexpr_non_global, 1) |
2175 | << IsReferenceType << !Designator.Entries.empty() |
2176 | << !!VD << VD; |
2177 | |
2178 | auto *VarD = dyn_cast_or_null<VarDecl>(VD); |
2179 | if (VarD && VarD->isConstexpr()) { |
2180 | // Non-static local constexpr variables have unintuitive semantics: |
2181 | // constexpr int a = 1; |
2182 | // constexpr const int *p = &a; |
2183 | // ... is invalid because the address of 'a' is not constant. Suggest |
2184 | // adding a 'static' in this case. |
2185 | Info.Note(VarD->getLocation(), diag::note_constexpr_not_static) |
2186 | << VarD |
2187 | << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static "); |
2188 | } else { |
2189 | NoteLValueLocation(Info, Base); |
2190 | } |
2191 | } else { |
2192 | Info.FFDiag(Loc); |
2193 | } |
2194 | // Don't allow references to temporaries to escape. |
2195 | return false; |
2196 | } |
2197 | assert((Info.checkingPotentialConstantExpression() ||((void)0) |
2198 | LVal.getLValueCallIndex() == 0) &&((void)0) |
2199 | "have call index for global lvalue")((void)0); |
2200 | |
2201 | if (Base.is<DynamicAllocLValue>()) { |
2202 | Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc) |
2203 | << IsReferenceType << !Designator.Entries.empty(); |
2204 | NoteLValueLocation(Info, Base); |
2205 | return false; |
2206 | } |
2207 | |
2208 | if (BaseVD) { |
2209 | if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) { |
2210 | // Check if this is a thread-local variable. |
2211 | if (Var->getTLSKind()) |
2212 | // FIXME: Diagnostic! |
2213 | return false; |
2214 | |
2215 | // A dllimport variable never acts like a constant, unless we're |
2216 | // evaluating a value for use only in name mangling. |
2217 | if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>()) |
2218 | // FIXME: Diagnostic! |
2219 | return false; |
2220 | } |
2221 | if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) { |
2222 | // __declspec(dllimport) must be handled very carefully: |
2223 | // We must never initialize an expression with the thunk in C++. |
2224 | // Doing otherwise would allow the same id-expression to yield |
2225 | // different addresses for the same function in different translation |
2226 | // units. However, this means that we must dynamically initialize the |
2227 | // expression with the contents of the import address table at runtime. |
2228 | // |
2229 | // The C language has no notion of ODR; furthermore, it has no notion of |
2230 | // dynamic initialization. This means that we are permitted to |
2231 | // perform initialization with the address of the thunk. |
2232 | if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) && |
2233 | FD->hasAttr<DLLImportAttr>()) |
2234 | // FIXME: Diagnostic! |
2235 | return false; |
2236 | } |
2237 | } else if (const auto *MTE = |
2238 | dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) { |
2239 | if (CheckedTemps.insert(MTE).second) { |
2240 | QualType TempType = getType(Base); |
2241 | if (TempType.isDestructedType()) { |
2242 | Info.FFDiag(MTE->getExprLoc(), |
2243 | diag::note_constexpr_unsupported_temporary_nontrivial_dtor) |
2244 | << TempType; |
2245 | return false; |
2246 | } |
2247 | |
2248 | APValue *V = MTE->getOrCreateValue(false); |
2249 | assert(V && "evasluation result refers to uninitialised temporary")((void)0); |
2250 | if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression, |
2251 | Info, MTE->getExprLoc(), TempType, *V, |
2252 | Kind, SourceLocation(), CheckedTemps)) |
2253 | return false; |
2254 | } |
2255 | } |
2256 | |
2257 | // Allow address constant expressions to be past-the-end pointers. This is |
2258 | // an extension: the standard requires them to point to an object. |
2259 | if (!IsReferenceType) |
2260 | return true; |
2261 | |
2262 | // A reference constant expression must refer to an object. |
2263 | if (!Base) { |
2264 | // FIXME: diagnostic |
2265 | Info.CCEDiag(Loc); |
2266 | return true; |
2267 | } |
2268 | |
2269 | // Does this refer one past the end of some object? |
2270 | if (!Designator.Invalid && Designator.isOnePastTheEnd()) { |
2271 | Info.FFDiag(Loc, diag::note_constexpr_past_end, 1) |
2272 | << !Designator.Entries.empty() << !!BaseVD << BaseVD; |
2273 | NoteLValueLocation(Info, Base); |
2274 | } |
2275 | |
2276 | return true; |
2277 | } |
2278 | |
2279 | /// Member pointers are constant expressions unless they point to a |
2280 | /// non-virtual dllimport member function. |
2281 | static bool CheckMemberPointerConstantExpression(EvalInfo &Info, |
2282 | SourceLocation Loc, |
2283 | QualType Type, |
2284 | const APValue &Value, |
2285 | ConstantExprKind Kind) { |
2286 | const ValueDecl *Member = Value.getMemberPointerDecl(); |
2287 | const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member); |
2288 | if (!FD) |
2289 | return true; |
2290 | if (FD->isConsteval()) { |
2291 | Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0; |
2292 | Info.Note(FD->getLocation(), diag::note_declared_at); |
2293 | return false; |
2294 | } |
2295 | return isForManglingOnly(Kind) || FD->isVirtual() || |
2296 | !FD->hasAttr<DLLImportAttr>(); |
2297 | } |
2298 | |
2299 | /// Check that this core constant expression is of literal type, and if not, |
2300 | /// produce an appropriate diagnostic. |
2301 | static bool CheckLiteralType(EvalInfo &Info, const Expr *E, |
2302 | const LValue *This = nullptr) { |
2303 | if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx)) |
2304 | return true; |
2305 | |
2306 | // C++1y: A constant initializer for an object o [...] may also invoke |
2307 | // constexpr constructors for o and its subobjects even if those objects |
2308 | // are of non-literal class types. |
2309 | // |
2310 | // C++11 missed this detail for aggregates, so classes like this: |
2311 | // struct foo_t { union { int i; volatile int j; } u; }; |
2312 | // are not (obviously) initializable like so: |
2313 | // __attribute__((__require_constant_initialization__)) |
2314 | // static const foo_t x = {{0}}; |
2315 | // because "i" is a subobject with non-literal initialization (due to the |
2316 | // volatile member of the union). See: |
2317 | // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677 |
2318 | // Therefore, we use the C++1y behavior. |
2319 | if (This && Info.EvaluatingDecl == This->getLValueBase()) |
2320 | return true; |
2321 | |
2322 | // Prvalue constant expressions must be of literal types. |
2323 | if (Info.getLangOpts().CPlusPlus11) |
2324 | Info.FFDiag(E, diag::note_constexpr_nonliteral) |
2325 | << E->getType(); |
2326 | else |
2327 | Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); |
2328 | return false; |
2329 | } |
2330 | |
2331 | static bool CheckEvaluationResult(CheckEvaluationResultKind CERK, |
2332 | EvalInfo &Info, SourceLocation DiagLoc, |
2333 | QualType Type, const APValue &Value, |
2334 | ConstantExprKind Kind, |
2335 | SourceLocation SubobjectLoc, |
2336 | CheckedTemporaries &CheckedTemps) { |
2337 | if (!Value.hasValue()) { |
2338 | Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) |
2339 | << true << Type; |
2340 | if (SubobjectLoc.isValid()) |
2341 | Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here); |
2342 | return false; |
2343 | } |
2344 | |
2345 | // We allow _Atomic(T) to be initialized from anything that T can be |
2346 | // initialized from. |
2347 | if (const AtomicType *AT = Type->getAs<AtomicType>()) |
2348 | Type = AT->getValueType(); |
2349 | |
2350 | // Core issue 1454: For a literal constant expression of array or class type, |
2351 | // each subobject of its value shall have been initialized by a constant |
2352 | // expression. |
2353 | if (Value.isArray()) { |
2354 | QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); |
2355 | for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { |
2356 | if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy, |
2357 | Value.getArrayInitializedElt(I), Kind, |
2358 | SubobjectLoc, CheckedTemps)) |
2359 | return false; |
2360 | } |
2361 | if (!Value.hasArrayFiller()) |
2362 | return true; |
2363 | return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy, |
2364 | Value.getArrayFiller(), Kind, SubobjectLoc, |
2365 | CheckedTemps); |
2366 | } |
2367 | if (Value.isUnion() && Value.getUnionField()) { |
2368 | return CheckEvaluationResult( |
2369 | CERK, Info, DiagLoc, Value.getUnionField()->getType(), |
2370 | Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(), |
2371 | CheckedTemps); |
2372 | } |
2373 | if (Value.isStruct()) { |
2374 | RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); |
2375 | if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { |
2376 | unsigned BaseIndex = 0; |
2377 | for (const CXXBaseSpecifier &BS : CD->bases()) { |
2378 | if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(), |
2379 | Value.getStructBase(BaseIndex), Kind, |
2380 | BS.getBeginLoc(), CheckedTemps)) |
2381 | return false; |
2382 | ++BaseIndex; |
2383 | } |
2384 | } |
2385 | for (const auto *I : RD->fields()) { |
2386 | if (I->isUnnamedBitfield()) |
2387 | continue; |
2388 | |
2389 | if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(), |
2390 | Value.getStructField(I->getFieldIndex()), |
2391 | Kind, I->getLocation(), CheckedTemps)) |
2392 | return false; |
2393 | } |
2394 | } |
2395 | |
2396 | if (Value.isLValue() && |
2397 | CERK == CheckEvaluationResultKind::ConstantExpression) { |
2398 | LValue LVal; |
2399 | LVal.setFrom(Info.Ctx, Value); |
2400 | return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind, |
2401 | CheckedTemps); |
2402 | } |
2403 | |
2404 | if (Value.isMemberPointer() && |
2405 | CERK == CheckEvaluationResultKind::ConstantExpression) |
2406 | return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind); |
2407 | |
2408 | // Everything else is fine. |
2409 | return true; |
2410 | } |
2411 | |
2412 | /// Check that this core constant expression value is a valid value for a |
2413 | /// constant expression. If not, report an appropriate diagnostic. Does not |
2414 | /// check that the expression is of literal type. |
2415 | static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, |
2416 | QualType Type, const APValue &Value, |
2417 | ConstantExprKind Kind) { |
2418 | // Nothing to check for a constant expression of type 'cv void'. |
2419 | if (Type->isVoidType()) |
2420 | return true; |
2421 | |
2422 | CheckedTemporaries CheckedTemps; |
2423 | return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression, |
2424 | Info, DiagLoc, Type, Value, Kind, |
2425 | SourceLocation(), CheckedTemps); |
2426 | } |
2427 | |
2428 | /// Check that this evaluated value is fully-initialized and can be loaded by |
2429 | /// an lvalue-to-rvalue conversion. |
2430 | static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc, |
2431 | QualType Type, const APValue &Value) { |
2432 | CheckedTemporaries CheckedTemps; |
2433 | return CheckEvaluationResult( |
2434 | CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value, |
2435 | ConstantExprKind::Normal, SourceLocation(), CheckedTemps); |
2436 | } |
2437 | |
2438 | /// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless |
2439 | /// "the allocated storage is deallocated within the evaluation". |
2440 | static bool CheckMemoryLeaks(EvalInfo &Info) { |
2441 | if (!Info.HeapAllocs.empty()) { |
2442 | // We can still fold to a constant despite a compile-time memory leak, |
2443 | // so long as the heap allocation isn't referenced in the result (we check |
2444 | // that in CheckConstantExpression). |
2445 | Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr, |
2446 | diag::note_constexpr_memory_leak) |
2447 | << unsigned(Info.HeapAllocs.size() - 1); |
2448 | } |
2449 | return true; |
2450 | } |
2451 | |
2452 | static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { |
2453 | // A null base expression indicates a null pointer. These are always |
2454 | // evaluatable, and they are false unless the offset is zero. |
2455 | if (!Value.getLValueBase()) { |
2456 | Result = !Value.getLValueOffset().isZero(); |
2457 | return true; |
2458 | } |
2459 | |
2460 | // We have a non-null base. These are generally known to be true, but if it's |
2461 | // a weak declaration it can be null at runtime. |
2462 | Result = true; |
2463 | const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); |
2464 | return !Decl || !Decl->isWeak(); |
2465 | } |
2466 | |
2467 | static bool HandleConversionToBool(const APValue &Val, bool &Result) { |
2468 | switch (Val.getKind()) { |
2469 | case APValue::None: |
2470 | case APValue::Indeterminate: |
2471 | return false; |
2472 | case APValue::Int: |
2473 | Result = Val.getInt().getBoolValue(); |
2474 | return true; |
2475 | case APValue::FixedPoint: |
2476 | Result = Val.getFixedPoint().getBoolValue(); |
2477 | return true; |
2478 | case APValue::Float: |
2479 | Result = !Val.getFloat().isZero(); |
2480 | return true; |
2481 | case APValue::ComplexInt: |
2482 | Result = Val.getComplexIntReal().getBoolValue() || |
2483 | Val.getComplexIntImag().getBoolValue(); |
2484 | return true; |
2485 | case APValue::ComplexFloat: |
2486 | Result = !Val.getComplexFloatReal().isZero() || |
2487 | !Val.getComplexFloatImag().isZero(); |
2488 | return true; |
2489 | case APValue::LValue: |
2490 | return EvalPointerValueAsBool(Val, Result); |
2491 | case APValue::MemberPointer: |
2492 | Result = Val.getMemberPointerDecl(); |
2493 | return true; |
2494 | case APValue::Vector: |
2495 | case APValue::Array: |
2496 | case APValue::Struct: |
2497 | case APValue::Union: |
2498 | case APValue::AddrLabelDiff: |
2499 | return false; |
2500 | } |
2501 | |
2502 | llvm_unreachable("unknown APValue kind")__builtin_unreachable(); |
2503 | } |
2504 | |
2505 | static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, |
2506 | EvalInfo &Info) { |
2507 | assert(!E->isValueDependent())((void)0); |
2508 | assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition")((void)0); |
2509 | APValue Val; |
2510 | if (!Evaluate(Val, Info, E)) |
2511 | return false; |
2512 | return HandleConversionToBool(Val, Result); |
2513 | } |
2514 | |
2515 | template<typename T> |
2516 | static bool HandleOverflow(EvalInfo &Info, const Expr *E, |
2517 | const T &SrcValue, QualType DestType) { |
2518 | Info.CCEDiag(E, diag::note_constexpr_overflow) |
2519 | << SrcValue << DestType; |
2520 | return Info.noteUndefinedBehavior(); |
2521 | } |
2522 | |
2523 | static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, |
2524 | QualType SrcType, const APFloat &Value, |
2525 | QualType DestType, APSInt &Result) { |
2526 | unsigned DestWidth = Info.Ctx.getIntWidth(DestType); |
2527 | // Determine whether we are converting to unsigned or signed. |
2528 | bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); |
2529 | |
2530 | Result = APSInt(DestWidth, !DestSigned); |
2531 | bool ignored; |
2532 | if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) |
2533 | & APFloat::opInvalidOp) |
2534 | return HandleOverflow(Info, E, Value, DestType); |
2535 | return true; |
2536 | } |
2537 | |
2538 | /// Get rounding mode used for evaluation of the specified expression. |
2539 | /// \param[out] DynamicRM Is set to true is the requested rounding mode is |
2540 | /// dynamic. |
2541 | /// If rounding mode is unknown at compile time, still try to evaluate the |
2542 | /// expression. If the result is exact, it does not depend on rounding mode. |
2543 | /// So return "tonearest" mode instead of "dynamic". |
2544 | static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E, |
2545 | bool &DynamicRM) { |
2546 | llvm::RoundingMode RM = |
2547 | E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode(); |
2548 | DynamicRM = (RM == llvm::RoundingMode::Dynamic); |
2549 | if (DynamicRM) |
2550 | RM = llvm::RoundingMode::NearestTiesToEven; |
2551 | return RM; |
2552 | } |
2553 | |
2554 | /// Check if the given evaluation result is allowed for constant evaluation. |
2555 | static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E, |
2556 | APFloat::opStatus St) { |
2557 | // In a constant context, assume that any dynamic rounding mode or FP |
2558 | // exception state matches the default floating-point environment. |
2559 | if (Info.InConstantContext) |
2560 | return true; |
2561 | |
2562 | FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()); |
2563 | if ((St & APFloat::opInexact) && |
2564 | FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) { |
2565 | // Inexact result means that it depends on rounding mode. If the requested |
2566 | // mode is dynamic, the evaluation cannot be made in compile time. |
2567 | Info.FFDiag(E, diag::note_constexpr_dynamic_rounding); |
2568 | return false; |
2569 | } |
2570 | |
2571 | if ((St != APFloat::opOK) && |
2572 | (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic || |
2573 | FPO.getFPExceptionMode() != LangOptions::FPE_Ignore || |
2574 | FPO.getAllowFEnvAccess())) { |
2575 | Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict); |
2576 | return false; |
2577 | } |
2578 | |
2579 | if ((St & APFloat::opStatus::opInvalidOp) && |
2580 | FPO.getFPExceptionMode() != LangOptions::FPE_Ignore) { |
2581 | // There is no usefully definable result. |
2582 | Info.FFDiag(E); |
2583 | return false; |
2584 | } |
2585 | |
2586 | // FIXME: if: |
2587 | // - evaluation triggered other FP exception, and |
2588 | // - exception mode is not "ignore", and |
2589 | // - the expression being evaluated is not a part of global variable |
2590 | // initializer, |
2591 | // the evaluation probably need to be rejected. |
2592 | return true; |
2593 | } |
2594 | |
2595 | static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, |
2596 | QualType SrcType, QualType DestType, |
2597 | APFloat &Result) { |
2598 | assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E))((void)0); |
2599 | bool DynamicRM; |
2600 | llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM); |
2601 | APFloat::opStatus St; |
2602 | APFloat Value = Result; |
2603 | bool ignored; |
2604 | St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored); |
2605 | return checkFloatingPointResult(Info, E, St); |
2606 | } |
2607 | |
2608 | static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, |
2609 | QualType DestType, QualType SrcType, |
2610 | const APSInt &Value) { |
2611 | unsigned DestWidth = Info.Ctx.getIntWidth(DestType); |
2612 | // Figure out if this is a truncate, extend or noop cast. |
2613 | // If the input is signed, do a sign extend, noop, or truncate. |
2614 | APSInt Result = Value.extOrTrunc(DestWidth); |
2615 | Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); |
2616 | if (DestType->isBooleanType()) |
2617 | Result = Value.getBoolValue(); |
2618 | return Result; |
2619 | } |
2620 | |
2621 | static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, |
2622 | const FPOptions FPO, |
2623 | QualType SrcType, const APSInt &Value, |
2624 | QualType DestType, APFloat &Result) { |
2625 | Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); |
2626 | APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(), |
2627 | APFloat::rmNearestTiesToEven); |
2628 | if (!Info.InConstantContext && St != llvm::APFloatBase::opOK && |
2629 | FPO.isFPConstrained()) { |
2630 | Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict); |
2631 | return false; |
2632 | } |
2633 | return true; |
2634 | } |
2635 | |
2636 | static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, |
2637 | APValue &Value, const FieldDecl *FD) { |
2638 | assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield")((void)0); |
2639 | |
2640 | if (!Value.isInt()) { |
2641 | // Trying to store a pointer-cast-to-integer into a bitfield. |
2642 | // FIXME: In this case, we should provide the diagnostic for casting |
2643 | // a pointer to an integer. |
2644 | assert(Value.isLValue() && "integral value neither int nor lvalue?")((void)0); |
2645 | Info.FFDiag(E); |
2646 | return false; |
2647 | } |
2648 | |
2649 | APSInt &Int = Value.getInt(); |
2650 | unsigned OldBitWidth = Int.getBitWidth(); |
2651 | unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); |
2652 | if (NewBitWidth < OldBitWidth) |
2653 | Int = Int.trunc(NewBitWidth).extend(OldBitWidth); |
2654 | return true; |
2655 | } |
2656 | |
2657 | static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, |
2658 | llvm::APInt &Res) { |
2659 | APValue SVal; |
2660 | if (!Evaluate(SVal, Info, E)) |
2661 | return false; |
2662 | if (SVal.isInt()) { |
2663 | Res = SVal.getInt(); |
2664 | return true; |
2665 | } |
2666 | if (SVal.isFloat()) { |
2667 | Res = SVal.getFloat().bitcastToAPInt(); |
2668 | return true; |
2669 | } |
2670 | if (SVal.isVector()) { |
2671 | QualType VecTy = E->getType(); |
2672 | unsigned VecSize = Info.Ctx.getTypeSize(VecTy); |
2673 | QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); |
2674 | unsigned EltSize = Info.Ctx.getTypeSize(EltTy); |
2675 | bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); |
2676 | Res = llvm::APInt::getNullValue(VecSize); |
2677 | for (unsigned i = 0; i < SVal.getVectorLength(); i++) { |
2678 | APValue &Elt = SVal.getVectorElt(i); |
2679 | llvm::APInt EltAsInt; |
2680 | if (Elt.isInt()) { |
2681 | EltAsInt = Elt.getInt(); |
2682 | } else if (Elt.isFloat()) { |
2683 | EltAsInt = Elt.getFloat().bitcastToAPInt(); |
2684 | } else { |
2685 | // Don't try to handle vectors of anything other than int or float |
2686 | // (not sure if it's possible to hit this case). |
2687 | Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); |
2688 | return false; |
2689 | } |
2690 | unsigned BaseEltSize = EltAsInt.getBitWidth(); |
2691 | if (BigEndian) |
2692 | Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); |
2693 | else |
2694 | Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); |
2695 | } |
2696 | return true; |
2697 | } |
2698 | // Give up if the input isn't an int, float, or vector. For example, we |
2699 | // reject "(v4i16)(intptr_t)&a". |
2700 | Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); |
2701 | return false; |
2702 | } |
2703 | |
2704 | /// Perform the given integer operation, which is known to need at most BitWidth |
2705 | /// bits, and check for overflow in the original type (if that type was not an |
2706 | /// unsigned type). |
2707 | template<typename Operation> |
2708 | static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E, |
2709 | const APSInt &LHS, const APSInt &RHS, |
2710 | unsigned BitWidth, Operation Op, |
2711 | APSInt &Result) { |
2712 | if (LHS.isUnsigned()) { |
2713 | Result = Op(LHS, RHS); |
2714 | return true; |
2715 | } |
2716 | |
2717 | APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); |
2718 | Result = Value.trunc(LHS.getBitWidth()); |
2719 | if (Result.extend(BitWidth) != Value) { |
2720 | if (Info.checkingForUndefinedBehavior()) |
2721 | Info.Ctx.getDiagnostics().Report(E->getExprLoc(), |
2722 | diag::warn_integer_constant_overflow) |
2723 | << toString(Result, 10) << E->getType(); |
2724 | return HandleOverflow(Info, E, Value, E->getType()); |
2725 | } |
2726 | return true; |
2727 | } |
2728 | |
2729 | /// Perform the given binary integer operation. |
2730 | static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, |
2731 | BinaryOperatorKind Opcode, APSInt RHS, |
2732 | APSInt &Result) { |
2733 | switch (Opcode) { |
2734 | default: |
2735 | Info.FFDiag(E); |
2736 | return false; |
2737 | case BO_Mul: |
2738 | return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, |
2739 | std::multiplies<APSInt>(), Result); |
2740 | case BO_Add: |
2741 | return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, |
2742 | std::plus<APSInt>(), Result); |
2743 | case BO_Sub: |
2744 | return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, |
2745 | std::minus<APSInt>(), Result); |
2746 | case BO_And: Result = LHS & RHS; return true; |
2747 | case BO_Xor: Result = LHS ^ RHS; return true; |
2748 | case BO_Or: Result = LHS | RHS; return true; |
2749 | case BO_Div: |
2750 | case BO_Rem: |
2751 | if (RHS == 0) { |
2752 | Info.FFDiag(E, diag::note_expr_divide_by_zero); |
2753 | return false; |
2754 | } |
2755 | Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); |
2756 | // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports |
2757 | // this operation and gives the two's complement result. |
2758 | if (RHS.isNegative() && RHS.isAllOnesValue() && |
2759 | LHS.isSigned() && LHS.isMinSignedValue()) |
2760 | return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), |
2761 | E->getType()); |
2762 | return true; |
2763 | case BO_Shl: { |
2764 | if (Info.getLangOpts().OpenCL) |
2765 | // OpenCL 6.3j: shift values are effectively % word size of LHS. |
2766 | RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), |
2767 | static_cast<uint64_t>(LHS.getBitWidth() - 1)), |
2768 | RHS.isUnsigned()); |
2769 | else if (RHS.isSigned() && RHS.isNegative()) { |
2770 | // During constant-folding, a negative shift is an opposite shift. Such |
2771 | // a shift is not a constant expression. |
2772 | Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; |
2773 | RHS = -RHS; |
2774 | goto shift_right; |
2775 | } |
2776 | shift_left: |
2777 | // C++11 [expr.shift]p1: Shift width must be less than the bit width of |
2778 | // the shifted type. |
2779 | unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); |
2780 | if (SA != RHS) { |
2781 | Info.CCEDiag(E, diag::note_constexpr_large_shift) |
2782 | << RHS << E->getType() << LHS.getBitWidth(); |
2783 | } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) { |
2784 | // C++11 [expr.shift]p2: A signed left shift must have a non-negative |
2785 | // operand, and must not overflow the corresponding unsigned type. |
2786 | // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to |
2787 | // E1 x 2^E2 module 2^N. |
2788 | if (LHS.isNegative()) |
2789 | Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; |
2790 | else if (LHS.countLeadingZeros() < SA) |
2791 | Info.CCEDiag(E, diag::note_constexpr_lshift_discards); |
2792 | } |
2793 | Result = LHS << SA; |
2794 | return true; |
2795 | } |
2796 | case BO_Shr: { |
2797 | if (Info.getLangOpts().OpenCL) |
2798 | // OpenCL 6.3j: shift values are effectively % word size of LHS. |
2799 | RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), |
2800 | static_cast<uint64_t>(LHS.getBitWidth() - 1)), |
2801 | RHS.isUnsigned()); |
2802 | else if (RHS.isSigned() && RHS.isNegative()) { |
2803 | // During constant-folding, a negative shift is an opposite shift. Such a |
2804 | // shift is not a constant expression. |
2805 | Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; |
2806 | RHS = -RHS; |
2807 | goto shift_left; |
2808 | } |
2809 | shift_right: |
2810 | // C++11 [expr.shift]p1: Shift width must be less than the bit width of the |
2811 | // shifted type. |
2812 | unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); |
2813 | if (SA != RHS) |
2814 | Info.CCEDiag(E, diag::note_constexpr_large_shift) |
2815 | << RHS << E->getType() << LHS.getBitWidth(); |
2816 | Result = LHS >> SA; |
2817 | return true; |
2818 | } |
2819 | |
2820 | case BO_LT: Result = LHS < RHS; return true; |
2821 | case BO_GT: Result = LHS > RHS; return true; |
2822 | case BO_LE: Result = LHS <= RHS; return true; |
2823 | case BO_GE: Result = LHS >= RHS; return true; |
2824 | case BO_EQ: Result = LHS == RHS; return true; |
2825 | case BO_NE: Result = LHS != RHS; return true; |
2826 | case BO_Cmp: |
2827 | llvm_unreachable("BO_Cmp should be handled elsewhere")__builtin_unreachable(); |
2828 | } |
2829 | } |
2830 | |
2831 | /// Perform the given binary floating-point operation, in-place, on LHS. |
2832 | static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E, |
2833 | APFloat &LHS, BinaryOperatorKind Opcode, |
2834 | const APFloat &RHS) { |
2835 | bool DynamicRM; |
2836 | llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM); |
2837 | APFloat::opStatus St; |
2838 | switch (Opcode) { |
2839 | default: |
2840 | Info.FFDiag(E); |
2841 | return false; |
2842 | case BO_Mul: |
2843 | St = LHS.multiply(RHS, RM); |
2844 | break; |
2845 | case BO_Add: |
2846 | St = LHS.add(RHS, RM); |
2847 | break; |
2848 | case BO_Sub: |
2849 | St = LHS.subtract(RHS, RM); |
2850 | break; |
2851 | case BO_Div: |
2852 | // [expr.mul]p4: |
2853 | // If the second operand of / or % is zero the behavior is undefined. |
2854 | if (RHS.isZero()) |
2855 | Info.CCEDiag(E, diag::note_expr_divide_by_zero); |
2856 | St = LHS.divide(RHS, RM); |
2857 | break; |
2858 | } |
2859 | |
2860 | // [expr.pre]p4: |
2861 | // If during the evaluation of an expression, the result is not |
2862 | // mathematically defined [...], the behavior is undefined. |
2863 | // FIXME: C++ rules require us to not conform to IEEE 754 here. |
2864 | if (LHS.isNaN()) { |
2865 | Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); |
2866 | return Info.noteUndefinedBehavior(); |
2867 | } |
2868 | |
2869 | return checkFloatingPointResult(Info, E, St); |
2870 | } |
2871 | |
2872 | static bool handleLogicalOpForVector(const APInt &LHSValue, |
2873 | BinaryOperatorKind Opcode, |
2874 | const APInt &RHSValue, APInt &Result) { |
2875 | bool LHS = (LHSValue != 0); |
2876 | bool RHS = (RHSValue != 0); |
2877 | |
2878 | if (Opcode == BO_LAnd) |
2879 | Result = LHS && RHS; |
2880 | else |
2881 | Result = LHS || RHS; |
2882 | return true; |
2883 | } |
2884 | static bool handleLogicalOpForVector(const APFloat &LHSValue, |
2885 | BinaryOperatorKind Opcode, |
2886 | const APFloat &RHSValue, APInt &Result) { |
2887 | bool LHS = !LHSValue.isZero(); |
2888 | bool RHS = !RHSValue.isZero(); |
2889 | |
2890 | if (Opcode == BO_LAnd) |
2891 | Result = LHS && RHS; |
2892 | else |
2893 | Result = LHS || RHS; |
2894 | return true; |
2895 | } |
2896 | |
2897 | static bool handleLogicalOpForVector(const APValue &LHSValue, |
2898 | BinaryOperatorKind Opcode, |
2899 | const APValue &RHSValue, APInt &Result) { |
2900 | // The result is always an int type, however operands match the first. |
2901 | if (LHSValue.getKind() == APValue::Int) |
2902 | return handleLogicalOpForVector(LHSValue.getInt(), Opcode, |
2903 | RHSValue.getInt(), Result); |
2904 | assert(LHSValue.getKind() == APValue::Float && "Should be no other options")((void)0); |
2905 | return handleLogicalOpForVector(LHSValue.getFloat(), Opcode, |
2906 | RHSValue.getFloat(), Result); |
2907 | } |
2908 | |
2909 | template <typename APTy> |
2910 | static bool |
2911 | handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode, |
2912 | const APTy &RHSValue, APInt &Result) { |
2913 | switch (Opcode) { |
2914 | default: |
2915 | llvm_unreachable("unsupported binary operator")__builtin_unreachable(); |
2916 | case BO_EQ: |
2917 | Result = (LHSValue == RHSValue); |
2918 | break; |
2919 | case BO_NE: |
2920 | Result = (LHSValue != RHSValue); |
2921 | break; |
2922 | case BO_LT: |
2923 | Result = (LHSValue < RHSValue); |
2924 | break; |
2925 | case BO_GT: |
2926 | Result = (LHSValue > RHSValue); |
2927 | break; |
2928 | case BO_LE: |
2929 | Result = (LHSValue <= RHSValue); |
2930 | break; |
2931 | case BO_GE: |
2932 | Result = (LHSValue >= RHSValue); |
2933 | break; |
2934 | } |
2935 | |
2936 | return true; |
2937 | } |
2938 | |
2939 | static bool handleCompareOpForVector(const APValue &LHSValue, |
2940 | BinaryOperatorKind Opcode, |
2941 | const APValue &RHSValue, APInt &Result) { |
2942 | // The result is always an int type, however operands match the first. |
2943 | if (LHSValue.getKind() == APValue::Int) |
2944 | return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode, |
2945 | RHSValue.getInt(), Result); |
2946 | assert(LHSValue.getKind() == APValue::Float && "Should be no other options")((void)0); |
2947 | return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode, |
2948 | RHSValue.getFloat(), Result); |
2949 | } |
2950 | |
2951 | // Perform binary operations for vector types, in place on the LHS. |
2952 | static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E, |
2953 | BinaryOperatorKind Opcode, |
2954 | APValue &LHSValue, |
2955 | const APValue &RHSValue) { |
2956 | assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&((void)0) |
2957 | "Operation not supported on vector types")((void)0); |
2958 | |
2959 | const auto *VT = E->getType()->castAs<VectorType>(); |
2960 | unsigned NumElements = VT->getNumElements(); |
2961 | QualType EltTy = VT->getElementType(); |
2962 | |
2963 | // In the cases (typically C as I've observed) where we aren't evaluating |
2964 | // constexpr but are checking for cases where the LHS isn't yet evaluatable, |
2965 | // just give up. |
2966 | if (!LHSValue.isVector()) { |
2967 | assert(LHSValue.isLValue() &&((void)0) |
2968 | "A vector result that isn't a vector OR uncalculated LValue")((void)0); |
2969 | Info.FFDiag(E); |
2970 | return false; |
2971 | } |
2972 | |
2973 | assert(LHSValue.getVectorLength() == NumElements &&((void)0) |
2974 | RHSValue.getVectorLength() == NumElements && "Different vector sizes")((void)0); |
2975 | |
2976 | SmallVector<APValue, 4> ResultElements; |
2977 | |
2978 | for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) { |
2979 | APValue LHSElt = LHSValue.getVectorElt(EltNum); |
2980 | APValue RHSElt = RHSValue.getVectorElt(EltNum); |
2981 | |
2982 | if (EltTy->isIntegerType()) { |
2983 | APSInt EltResult{Info.Ctx.getIntWidth(EltTy), |
2984 | EltTy->isUnsignedIntegerType()}; |
2985 | bool Success = true; |
2986 | |
2987 | if (BinaryOperator::isLogicalOp(Opcode)) |
2988 | Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult); |
2989 | else if (BinaryOperator::isComparisonOp(Opcode)) |
2990 | Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult); |
2991 | else |
2992 | Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode, |
2993 | RHSElt.getInt(), EltResult); |
2994 | |
2995 | if (!Success) { |
2996 | Info.FFDiag(E); |
2997 | return false; |
2998 | } |
2999 | ResultElements.emplace_back(EltResult); |
3000 | |
3001 | } else if (EltTy->isFloatingType()) { |
3002 | assert(LHSElt.getKind() == APValue::Float &&((void)0) |
3003 | RHSElt.getKind() == APValue::Float &&((void)0) |
3004 | "Mismatched LHS/RHS/Result Type")((void)0); |
3005 | APFloat LHSFloat = LHSElt.getFloat(); |
3006 | |
3007 | if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode, |
3008 | RHSElt.getFloat())) { |
3009 | Info.FFDiag(E); |
3010 | return false; |
3011 | } |
3012 | |
3013 | ResultElements.emplace_back(LHSFloat); |
3014 | } |
3015 | } |
3016 | |
3017 | LHSValue = APValue(ResultElements.data(), ResultElements.size()); |
3018 | return true; |
3019 | } |
3020 | |
3021 | /// Cast an lvalue referring to a base subobject to a derived class, by |
3022 | /// truncating the lvalue's path to the given length. |
3023 | static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, |
3024 | const RecordDecl *TruncatedType, |
3025 | unsigned TruncatedElements) { |
3026 | SubobjectDesignator &D = Result.Designator; |
3027 | |
3028 | // Check we actually point to a derived class object. |
3029 | if (TruncatedElements == D.Entries.size()) |
3030 | return true; |
3031 | assert(TruncatedElements >= D.MostDerivedPathLength &&((void)0) |
3032 | "not casting to a derived class")((void)0); |
3033 | if (!Result.checkSubobject(Info, E, CSK_Derived)) |
3034 | return false; |
3035 | |
3036 | // Truncate the path to the subobject, and remove any derived-to-base offsets. |
3037 | const RecordDecl *RD = TruncatedType; |
3038 | for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { |
3039 | if (RD->isInvalidDecl()) return false; |
3040 | const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); |
3041 | const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); |
3042 | if (isVirtualBaseClass(D.Entries[I])) |
3043 | Result.Offset -= Layout.getVBaseClassOffset(Base); |
3044 | else |
3045 | Result.Offset -= Layout.getBaseClassOffset(Base); |
3046 | RD = Base; |
3047 | } |
3048 | D.Entries.resize(TruncatedElements); |
3049 | return true; |
3050 | } |
3051 | |
3052 | static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, |
3053 | const CXXRecordDecl *Derived, |
3054 | const CXXRecordDecl *Base, |
3055 | const ASTRecordLayout *RL = nullptr) { |
3056 | if (!RL) { |
3057 | if (Derived->isInvalidDecl()) return false; |
3058 | RL = &Info.Ctx.getASTRecordLayout(Derived); |
3059 | } |
3060 | |
3061 | Obj.getLValueOffset() += RL->getBaseClassOffset(Base); |
3062 | Obj.addDecl(Info, E, Base, /*Virtual*/ false); |
3063 | return true; |
3064 | } |
3065 | |
3066 | static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, |
3067 | const CXXRecordDecl *DerivedDecl, |
3068 | const CXXBaseSpecifier *Base) { |
3069 | const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); |
3070 | |
3071 | if (!Base->isVirtual()) |
3072 | return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); |
3073 | |
3074 | SubobjectDesignator &D = Obj.Designator; |
3075 | if (D.Invalid) |
3076 | return false; |
3077 | |
3078 | // Extract most-derived object and corresponding type. |
3079 | DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); |
3080 | if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) |
3081 | return false; |
3082 | |
3083 | // Find the virtual base class. |
3084 | if (DerivedDecl->isInvalidDecl()) return false; |
3085 | const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); |
3086 | Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); |
3087 | Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); |
3088 | return true; |
3089 | } |
3090 | |
3091 | static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, |
3092 | QualType Type, LValue &Result) { |
3093 | for (CastExpr::path_const_iterator PathI = E->path_begin(), |
3094 | PathE = E->path_end(); |
3095 | PathI != PathE; ++PathI) { |
3096 | if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), |
3097 | *PathI)) |
3098 | return false; |
3099 | Type = (*PathI)->getType(); |
3100 | } |
3101 | return true; |
3102 | } |
3103 | |
3104 | /// Cast an lvalue referring to a derived class to a known base subobject. |
3105 | static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result, |
3106 | const CXXRecordDecl *DerivedRD, |
3107 | const CXXRecordDecl *BaseRD) { |
3108 | CXXBasePaths Paths(/*FindAmbiguities=*/false, |
3109 | /*RecordPaths=*/true, /*DetectVirtual=*/false); |
3110 | if (!DerivedRD->isDerivedFrom(BaseRD, Paths)) |
3111 | llvm_unreachable("Class must be derived from the passed in base class!")__builtin_unreachable(); |
3112 | |
3113 | for (CXXBasePathElement &Elem : Paths.front()) |
3114 | if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base)) |
3115 | return false; |
3116 | return true; |
3117 | } |
3118 | |
3119 | /// Update LVal to refer to the given field, which must be a member of the type |
3120 | /// currently described by LVal. |
3121 | static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, |
3122 | const FieldDecl *FD, |
3123 | const ASTRecordLayout *RL = nullptr) { |
3124 | if (!RL) { |
3125 | if (FD->getParent()->isInvalidDecl()) return false; |
3126 | RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); |
3127 | } |
3128 | |
3129 | unsigned I = FD->getFieldIndex(); |
3130 | LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I))); |
3131 | LVal.addDecl(Info, E, FD); |
3132 | return true; |
3133 | } |
3134 | |
3135 | /// Update LVal to refer to the given indirect field. |
3136 | static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, |
3137 | LValue &LVal, |
3138 | const IndirectFieldDecl *IFD) { |
3139 | for (const auto *C : IFD->chain()) |
3140 | if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C))) |
3141 | return false; |
3142 | return true; |
3143 | } |
3144 | |
3145 | /// Get the size of the given type in char units. |
3146 | static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, |
3147 | QualType Type, CharUnits &Size) { |
3148 | // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc |
3149 | // extension. |
3150 | if (Type->isVoidType() || Type->isFunctionType()) { |
3151 | Size = CharUnits::One(); |
3152 | return true; |
3153 | } |
3154 | |
3155 | if (Type->isDependentType()) { |
3156 | Info.FFDiag(Loc); |
3157 | return false; |
3158 | } |
3159 | |
3160 | if (!Type->isConstantSizeType()) { |
3161 | // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. |
3162 | // FIXME: Better diagnostic. |
3163 | Info.FFDiag(Loc); |
3164 | return false; |
3165 | } |
3166 | |
3167 | Size = Info.Ctx.getTypeSizeInChars(Type); |
3168 | return true; |
3169 | } |
3170 | |
3171 | /// Update a pointer value to model pointer arithmetic. |
3172 | /// \param Info - Information about the ongoing evaluation. |
3173 | /// \param E - The expression being evaluated, for diagnostic purposes. |
3174 | /// \param LVal - The pointer value to be updated. |
3175 | /// \param EltTy - The pointee type represented by LVal. |
3176 | /// \param Adjustment - The adjustment, in objects of type EltTy, to add. |
3177 | static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, |
3178 | LValue &LVal, QualType EltTy, |
3179 | APSInt Adjustment) { |
3180 | CharUnits SizeOfPointee; |
3181 | if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) |
3182 | return false; |
3183 | |
3184 | LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee); |
3185 | return true; |
3186 | } |
3187 | |
3188 | static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, |
3189 | LValue &LVal, QualType EltTy, |
3190 | int64_t Adjustment) { |
3191 | return HandleLValueArrayAdjustment(Info, E, LVal, EltTy, |
3192 | APSInt::get(Adjustment)); |
3193 | } |
3194 | |
3195 | /// Update an lvalue to refer to a component of a complex number. |
3196 | /// \param Info - Information about the ongoing evaluation. |
3197 | /// \param LVal - The lvalue to be updated. |
3198 | /// \param EltTy - The complex number's component type. |
3199 | /// \param Imag - False for the real component, true for the imaginary. |
3200 | static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, |
3201 | LValue &LVal, QualType EltTy, |
3202 | bool Imag) { |
3203 | if (Imag) { |
3204 | CharUnits SizeOfComponent; |
3205 | if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) |
3206 | return false; |
3207 | LVal.Offset += SizeOfComponent; |
3208 | } |
3209 | LVal.addComplex(Info, E, EltTy, Imag); |
3210 | return true; |
3211 | } |
3212 | |
3213 | /// Try to evaluate the initializer for a variable declaration. |
3214 | /// |
3215 | /// \param Info Information about the ongoing evaluation. |
3216 | /// \param E An expression to be used when printing diagnostics. |
3217 | /// \param VD The variable whose initializer should be obtained. |
3218 | /// \param Version The version of the variable within the frame. |
3219 | /// \param Frame The frame in which the variable was created. Must be null |
3220 | /// if this variable is not local to the evaluation. |
3221 | /// \param Result Filled in with a pointer to the value of the variable. |
3222 | static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, |
3223 | const VarDecl *VD, CallStackFrame *Frame, |
3224 | unsigned Version, APValue *&Result) { |
3225 | APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version); |
3226 | |
3227 | // If this is a local variable, dig out its value. |
3228 | if (Frame) { |
3229 | Result = Frame->getTemporary(VD, Version); |
3230 | if (Result) |
3231 | return true; |
3232 | |
3233 | if (!isa<ParmVarDecl>(VD)) { |
3234 | // Assume variables referenced within a lambda's call operator that were |
3235 | // not declared within the call operator are captures and during checking |
3236 | // of a potential constant expression, assume they are unknown constant |
3237 | // expressions. |
3238 | assert(isLambdaCallOperator(Frame->Callee) &&((void)0) |
3239 | (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&((void)0) |
3240 | "missing value for local variable")((void)0); |
3241 | if (Info.checkingPotentialConstantExpression()) |
3242 | return false; |
3243 | // FIXME: This diagnostic is bogus; we do support captures. Is this code |
3244 | // still reachable at all? |
3245 | Info.FFDiag(E->getBeginLoc(), |
3246 | diag::note_unimplemented_constexpr_lambda_feature_ast) |
3247 | << "captures not currently allowed"; |
3248 | return false; |
3249 | } |
3250 | } |
3251 | |
3252 | // If we're currently evaluating the initializer of this declaration, use that |
3253 | // in-flight value. |
3254 | if (Info.EvaluatingDecl == Base) { |
3255 | Result = Info.EvaluatingDeclValue; |
3256 | return true; |
3257 | } |
3258 | |
3259 | if (isa<ParmVarDecl>(VD)) { |
3260 | // Assume parameters of a potential constant expression are usable in |
3261 | // constant expressions. |
3262 | if (!Info.checkingPotentialConstantExpression() || |
3263 | !Info.CurrentCall->Callee || |
3264 | !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) { |
3265 | if (Info.getLangOpts().CPlusPlus11) { |
3266 | Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown) |
3267 | << VD; |
3268 | NoteLValueLocation(Info, Base); |
3269 | } else { |
3270 | Info.FFDiag(E); |
3271 | } |
3272 | } |
3273 | return false; |
3274 | } |
3275 | |
3276 | // Dig out the initializer, and use the declaration which it's attached to. |
3277 | // FIXME: We should eventually check whether the variable has a reachable |
3278 | // initializing declaration. |
3279 | const Expr *Init = VD->getAnyInitializer(VD); |
3280 | if (!Init) { |
3281 | // Don't diagnose during potential constant expression checking; an |
3282 | // initializer might be added later. |
3283 | if (!Info.checkingPotentialConstantExpression()) { |
3284 | Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1) |
3285 | << VD; |
3286 | NoteLValueLocation(Info, Base); |
3287 | } |
3288 | return false; |
3289 | } |
3290 | |
3291 | if (Init->isValueDependent()) { |
3292 | // The DeclRefExpr is not value-dependent, but the variable it refers to |
3293 | // has a value-dependent initializer. This should only happen in |
3294 | // constant-folding cases, where the variable is not actually of a suitable |
3295 | // type for use in a constant expression (otherwise the DeclRefExpr would |
3296 | // have been value-dependent too), so diagnose that. |
3297 | assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx))((void)0); |
3298 | if (!Info.checkingPotentialConstantExpression()) { |
3299 | Info.FFDiag(E, Info.getLangOpts().CPlusPlus11 |
3300 | ? diag::note_constexpr_ltor_non_constexpr |
3301 | : diag::note_constexpr_ltor_non_integral, 1) |
3302 | << VD << VD->getType(); |
3303 | NoteLValueLocation(Info, Base); |
3304 | } |
3305 | return false; |
3306 | } |
3307 | |
3308 | // Check that we can fold the initializer. In C++, we will have already done |
3309 | // this in the cases where it matters for conformance. |
3310 | if (!VD->evaluateValue()) { |
3311 | Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD; |
3312 | NoteLValueLocation(Info, Base); |
3313 | return false; |
3314 | } |
3315 | |
3316 | // Check that the variable is actually usable in constant expressions. For a |
3317 | // const integral variable or a reference, we might have a non-constant |
3318 | // initializer that we can nonetheless evaluate the initializer for. Such |
3319 | // variables are not usable in constant expressions. In C++98, the |
3320 | // initializer also syntactically needs to be an ICE. |
3321 | // |
3322 | // FIXME: We don't diagnose cases that aren't potentially usable in constant |
3323 | // expressions here; doing so would regress diagnostics for things like |
3324 | // reading from a volatile constexpr variable. |
3325 | if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() && |
3326 | VD->mightBeUsableInConstantExpressions(Info.Ctx)) || |
3327 | ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) && |
3328 | !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) { |
3329 | Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD; |
3330 | NoteLValueLocation(Info, Base); |
3331 | } |
3332 | |
3333 | // Never use the initializer of a weak variable, not even for constant |
3334 | // folding. We can't be sure that this is the definition that will be used. |
3335 | if (VD->isWeak()) { |
3336 | Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD; |
3337 | NoteLValueLocation(Info, Base); |
3338 | return false; |
3339 | } |
3340 | |
3341 | Result = VD->getEvaluatedValue(); |
3342 | return true; |
3343 | } |
3344 | |
3345 | /// Get the base index of the given base class within an APValue representing |
3346 | /// the given derived class. |
3347 | static unsigned getBaseIndex(const CXXRecordDecl *Derived, |
3348 | const CXXRecordDecl *Base) { |
3349 | Base = Base->getCanonicalDecl(); |
3350 | unsigned Index = 0; |
3351 | for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), |
3352 | E = Derived->bases_end(); I != E; ++I, ++Index) { |
3353 | if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) |
3354 | return Index; |
3355 | } |
3356 | |
3357 | llvm_unreachable("base class missing from derived class's bases list")__builtin_unreachable(); |
3358 | } |
3359 | |
3360 | /// Extract the value of a character from a string literal. |
3361 | static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, |
3362 | uint64_t Index) { |
3363 | assert(!isa<SourceLocExpr>(Lit) &&((void)0) |
3364 | "SourceLocExpr should have already been converted to a StringLiteral")((void)0); |
3365 | |
3366 | // FIXME: Support MakeStringConstant |
3367 | if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) { |
3368 | std::string Str; |
3369 | Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str); |
3370 | assert(Index <= Str.size() && "Index too large")((void)0); |
3371 | return APSInt::getUnsigned(Str.c_str()[Index]); |
3372 | } |
3373 | |
3374 | if (auto PE = dyn_cast<PredefinedExpr>(Lit)) |
3375 | Lit = PE->getFunctionName(); |
3376 | const StringLiteral *S = cast<StringLiteral>(Lit); |
3377 | const ConstantArrayType *CAT = |
3378 | Info.Ctx.getAsConstantArrayType(S->getType()); |
3379 | assert(CAT && "string literal isn't an array")((void)0); |
3380 | QualType CharType = CAT->getElementType(); |
3381 | assert(CharType->isIntegerType() && "unexpected character type")((void)0); |
3382 | |
3383 | APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), |
3384 | CharType->isUnsignedIntegerType()); |
3385 | if (Index < S->getLength()) |
3386 | Value = S->getCodeUnit(Index); |
3387 | return Value; |
3388 | } |
3389 | |
3390 | // Expand a string literal into an array of characters. |
3391 | // |
3392 | // FIXME: This is inefficient; we should probably introduce something similar |
3393 | // to the LLVM ConstantDataArray to make this cheaper. |
3394 | static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S, |
3395 | APValue &Result, |
3396 | QualType AllocType = QualType()) { |
3397 | const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType( |
3398 | AllocType.isNull() ? S->getType() : AllocType); |
3399 | assert(CAT && "string literal isn't an array")((void)0); |
3400 | QualType CharType = CAT->getElementType(); |
3401 | assert(CharType->isIntegerType() && "unexpected character type")((void)0); |
3402 | |
3403 | unsigned Elts = CAT->getSize().getZExtValue(); |
3404 | Result = APValue(APValue::UninitArray(), |
3405 | std::min(S->getLength(), Elts), Elts); |
3406 | APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), |
3407 | CharType->isUnsignedIntegerType()); |
3408 | if (Result.hasArrayFiller()) |
3409 | Result.getArrayFiller() = APValue(Value); |
3410 | for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { |
3411 | Value = S->getCodeUnit(I); |
3412 | Result.getArrayInitializedElt(I) = APValue(Value); |
3413 | } |
3414 | } |
3415 | |
3416 | // Expand an array so that it has more than Index filled elements. |
3417 | static void expandArray(APValue &Array, unsigned Index) { |
3418 | unsigned Size = Array.getArraySize(); |
3419 | assert(Index < Size)((void)0); |
3420 | |
3421 | // Always at least double the number of elements for which we store a value. |
3422 | unsigned OldElts = Array.getArrayInitializedElts(); |
3423 | unsigned NewElts = std::max(Index+1, OldElts * 2); |
3424 | NewElts = std::min(Size, std::max(NewElts, 8u)); |
3425 | |
3426 | // Copy the data across. |
3427 | APValue NewValue(APValue::UninitArray(), NewElts, Size); |
3428 | for (unsigned I = 0; I != OldElts; ++I) |
3429 | NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); |
3430 | for (unsigned I = OldElts; I != NewElts; ++I) |
3431 | NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); |
3432 | if (NewValue.hasArrayFiller()) |
3433 | NewValue.getArrayFiller() = Array.getArrayFiller(); |
3434 | Array.swap(NewValue); |
3435 | } |
3436 | |
3437 | /// Determine whether a type would actually be read by an lvalue-to-rvalue |
3438 | /// conversion. If it's of class type, we may assume that the copy operation |
3439 | /// is trivial. Note that this is never true for a union type with fields |
3440 | /// (because the copy always "reads" the active member) and always true for |
3441 | /// a non-class type. |
3442 | static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD); |
3443 | static bool isReadByLvalueToRvalueConversion(QualType T) { |
3444 | CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); |
3445 | return !RD || isReadByLvalueToRvalueConversion(RD); |
3446 | } |
3447 | static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) { |
3448 | // FIXME: A trivial copy of a union copies the object representation, even if |
3449 | // the union is empty. |
3450 | if (RD->isUnion()) |
3451 | return !RD->field_empty(); |
3452 | if (RD->isEmpty()) |
3453 | return false; |
3454 | |
3455 | for (auto *Field : RD->fields()) |
3456 | if (!Field->isUnnamedBitfield() && |
3457 | isReadByLvalueToRvalueConversion(Field->getType())) |
3458 | return true; |
3459 | |
3460 | for (auto &BaseSpec : RD->bases()) |
3461 | if (isReadByLvalueToRvalueConversion(BaseSpec.getType())) |
3462 | return true; |
3463 | |
3464 | return false; |
3465 | } |
3466 | |
3467 | /// Diagnose an attempt to read from any unreadable field within the specified |
3468 | /// type, which might be a class type. |
3469 | static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK, |
3470 | QualType T) { |
3471 | CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); |
3472 | if (!RD) |
3473 | return false; |
3474 | |
3475 | if (!RD->hasMutableFields()) |
3476 | return false; |
3477 | |
3478 | for (auto *Field : RD->fields()) { |
3479 | // If we're actually going to read this field in some way, then it can't |
3480 | // be mutable. If we're in a union, then assigning to a mutable field |
3481 | // (even an empty one) can change the active member, so that's not OK. |
3482 | // FIXME: Add core issue number for the union case. |
3483 | if (Field->isMutable() && |
3484 | (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) { |
3485 | Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field; |
3486 | Info.Note(Field->getLocation(), diag::note_declared_at); |
3487 | return true; |
3488 | } |
3489 | |
3490 | if (diagnoseMutableFields(Info, E, AK, Field->getType())) |
3491 | return true; |
3492 | } |
3493 | |
3494 | for (auto &BaseSpec : RD->bases()) |
3495 | if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType())) |
3496 | return true; |
3497 | |
3498 | // All mutable fields were empty, and thus not actually read. |
3499 | return false; |
3500 | } |
3501 | |
3502 | static bool lifetimeStartedInEvaluation(EvalInfo &Info, |
3503 | APValue::LValueBase Base, |
3504 | bool MutableSubobject = false) { |
3505 | // A temporary or transient heap allocation we created. |
3506 | if (Base.getCallIndex() || Base.is<DynamicAllocLValue>()) |
3507 | return true; |
3508 | |
3509 | switch (Info.IsEvaluatingDecl) { |
3510 | case EvalInfo::EvaluatingDeclKind::None: |
3511 | return false; |
3512 | |
3513 | case EvalInfo::EvaluatingDeclKind::Ctor: |
3514 | // The variable whose initializer we're evaluating. |
3515 | if (Info.EvaluatingDecl == Base) |
3516 | return true; |
3517 | |
3518 | // A temporary lifetime-extended by the variable whose initializer we're |
3519 | // evaluating. |
3520 | if (auto *BaseE = Base.dyn_cast<const Expr *>()) |
3521 | if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE)) |
3522 | return Info.EvaluatingDecl == BaseMTE->getExtendingDecl(); |
3523 | return false; |
3524 | |
3525 | case EvalInfo::EvaluatingDeclKind::Dtor: |
3526 | // C++2a [expr.const]p6: |
3527 | // [during constant destruction] the lifetime of a and its non-mutable |
3528 | // subobjects (but not its mutable subobjects) [are] considered to start |
3529 | // within e. |
3530 | if (MutableSubobject || Base != Info.EvaluatingDecl) |
3531 | return false; |
3532 | // FIXME: We can meaningfully extend this to cover non-const objects, but |
3533 | // we will need special handling: we should be able to access only |
3534 | // subobjects of such objects that are themselves declared const. |
3535 | QualType T = getType(Base); |
3536 | return T.isConstQualified() || T->isReferenceType(); |
3537 | } |
3538 | |
3539 | llvm_unreachable("unknown evaluating decl kind")__builtin_unreachable(); |
3540 | } |
3541 | |
3542 | namespace { |
3543 | /// A handle to a complete object (an object that is not a subobject of |
3544 | /// another object). |
3545 | struct CompleteObject { |
3546 | /// The identity of the object. |
3547 | APValue::LValueBase Base; |
3548 | /// The value of the complete object. |
3549 | APValue *Value; |
3550 | /// The type of the complete object. |
3551 | QualType Type; |
3552 | |
3553 | CompleteObject() : Value(nullptr) {} |
3554 | CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type) |
3555 | : Base(Base), Value(Value), Type(Type) {} |
3556 | |
3557 | bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const { |
3558 | // If this isn't a "real" access (eg, if it's just accessing the type |
3559 | // info), allow it. We assume the type doesn't change dynamically for |
3560 | // subobjects of constexpr objects (even though we'd hit UB here if it |
3561 | // did). FIXME: Is this right? |
3562 | if (!isAnyAccess(AK)) |
3563 | return true; |
3564 | |
3565 | // In C++14 onwards, it is permitted to read a mutable member whose |
3566 | // lifetime began within the evaluation. |
3567 | // FIXME: Should we also allow this in C++11? |
3568 | if (!Info.getLangOpts().CPlusPlus14) |
3569 | return false; |
3570 | return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true); |
3571 | } |
3572 | |
3573 | explicit operator bool() const { return !Type.isNull(); } |
3574 | }; |
3575 | } // end anonymous namespace |
3576 | |
3577 | static QualType getSubobjectType(QualType ObjType, QualType SubobjType, |
3578 | bool IsMutable = false) { |
3579 | // C++ [basic.type.qualifier]p1: |
3580 | // - A const object is an object of type const T or a non-mutable subobject |
3581 | // of a const object. |
3582 | if (ObjType.isConstQualified() && !IsMutable) |
3583 | SubobjType.addConst(); |
3584 | // - A volatile object is an object of type const T or a subobject of a |
3585 | // volatile object. |
3586 | if (ObjType.isVolatileQualified()) |
3587 | SubobjType.addVolatile(); |
3588 | return SubobjType; |
3589 | } |
3590 | |
3591 | /// Find the designated sub-object of an rvalue. |
3592 | template<typename SubobjectHandler> |
3593 | typename SubobjectHandler::result_type |
3594 | findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, |
3595 | const SubobjectDesignator &Sub, SubobjectHandler &handler) { |
3596 | if (Sub.Invalid) |
3597 | // A diagnostic will have already been produced. |
3598 | return handler.failed(); |
3599 | if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) { |
3600 | if (Info.getLangOpts().CPlusPlus11) |
3601 | Info.FFDiag(E, Sub.isOnePastTheEnd() |
3602 | ? diag::note_constexpr_access_past_end |
3603 | : diag::note_constexpr_access_unsized_array) |
3604 | << handler.AccessKind; |
3605 | else |
3606 | Info.FFDiag(E); |
3607 | return handler.failed(); |
3608 | } |
3609 | |
3610 | APValue *O = Obj.Value; |
3611 | QualType ObjType = Obj.Type; |
3612 | const FieldDecl *LastField = nullptr; |
3613 | const FieldDecl *VolatileField = nullptr; |
3614 | |
3615 | // Walk the designator's path to find the subobject. |
3616 | for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { |
3617 | // Reading an indeterminate value is undefined, but assigning over one is OK. |
3618 | if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) || |
3619 | (O->isIndeterminate() && |
3620 | !isValidIndeterminateAccess(handler.AccessKind))) { |
3621 | if (!Info.checkingPotentialConstantExpression()) |
3622 | Info.FFDiag(E, diag::note_constexpr_access_uninit) |
3623 | << handler.AccessKind << O->isIndeterminate(); |
3624 | return handler.failed(); |
3625 | } |
3626 | |
3627 | // C++ [class.ctor]p5, C++ [class.dtor]p5: |
3628 | // const and volatile semantics are not applied on an object under |
3629 | // {con,de}struction. |
3630 | if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) && |
3631 | ObjType->isRecordType() && |
3632 | Info.isEvaluatingCtorDtor( |
3633 | Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(), |
3634 | Sub.Entries.begin() + I)) != |
3635 | ConstructionPhase::None) { |
3636 | ObjType = Info.Ctx.getCanonicalType(ObjType); |
3637 | ObjType.removeLocalConst(); |
3638 | ObjType.removeLocalVolatile(); |
3639 | } |
3640 | |
3641 | // If this is our last pass, check that the final object type is OK. |
3642 | if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) { |
3643 | // Accesses to volatile objects are prohibited. |
3644 | if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) { |
3645 | if (Info.getLangOpts().CPlusPlus) { |
3646 | int DiagKind; |
3647 | SourceLocation Loc; |
3648 | const NamedDecl *Decl = nullptr; |
3649 | if (VolatileField) { |
3650 | DiagKind = 2; |
3651 | Loc = VolatileField->getLocation(); |
3652 | Decl = VolatileField; |
3653 | } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) { |
3654 | DiagKind = 1; |
3655 | Loc = VD->getLocation(); |
3656 | Decl = VD; |
3657 | } else { |
3658 | DiagKind = 0; |
3659 | if (auto *E = Obj.Base.dyn_cast<const Expr *>()) |
3660 | Loc = E->getExprLoc(); |
3661 | } |
3662 | Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) |
3663 | << handler.AccessKind << DiagKind << Decl; |
3664 | Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind; |
3665 | } else { |
3666 | Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); |
3667 | } |
3668 | return handler.failed(); |
3669 | } |
3670 | |
3671 | // If we are reading an object of class type, there may still be more |
3672 | // things we need to check: if there are any mutable subobjects, we |
3673 | // cannot perform this read. (This only happens when performing a trivial |
3674 | // copy or assignment.) |
3675 | if (ObjType->isRecordType() && |
3676 | !Obj.mayAccessMutableMembers(Info, handler.AccessKind) && |
3677 | diagnoseMutableFields(Info, E, handler.AccessKind, ObjType)) |
3678 | return handler.failed(); |
3679 | } |
3680 | |
3681 | if (I == N) { |
3682 | if (!handler.found(*O, ObjType)) |
3683 | return false; |
3684 | |
3685 | // If we modified a bit-field, truncate it to the right width. |
3686 | if (isModification(handler.AccessKind) && |
3687 | LastField && LastField->isBitField() && |
3688 | !truncateBitfieldValue(Info, E, *O, LastField)) |
3689 | return false; |
3690 | |
3691 | return true; |
3692 | } |
3693 | |
3694 | LastField = nullptr; |
3695 | if (ObjType->isArrayType()) { |
3696 | // Next subobject is an array element. |
3697 | const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); |
3698 | assert(CAT && "vla in literal type?")((void)0); |
3699 | uint64_t Index = Sub.Entries[I].getAsArrayIndex(); |
3700 | if (CAT->getSize().ule(Index)) { |
3701 | // Note, it should not be possible to form a pointer with a valid |
3702 | // designator which points more than one past the end of the array. |
3703 | if (Info.getLangOpts().CPlusPlus11) |
3704 | Info.FFDiag(E, diag::note_constexpr_access_past_end) |
3705 | << handler.AccessKind; |
3706 | else |
3707 | Info.FFDiag(E); |
3708 | return handler.failed(); |
3709 | } |
3710 | |
3711 | ObjType = CAT->getElementType(); |
3712 | |
3713 | if (O->getArrayInitializedElts() > Index) |
3714 | O = &O->getArrayInitializedElt(Index); |
3715 | else if (!isRead(handler.AccessKind)) { |
3716 | expandArray(*O, Index); |
3717 | O = &O->getArrayInitializedElt(Index); |
3718 | } else |
3719 | O = &O->getArrayFiller(); |
3720 | } else if (ObjType->isAnyComplexType()) { |
3721 | // Next subobject is a complex number. |
3722 | uint64_t Index = Sub.Entries[I].getAsArrayIndex(); |
3723 | if (Index > 1) { |
3724 | if (Info.getLangOpts().CPlusPlus11) |
3725 | Info.FFDiag(E, diag::note_constexpr_access_past_end) |
3726 | << handler.AccessKind; |
3727 | else |
3728 | Info.FFDiag(E); |
3729 | return handler.failed(); |
3730 | } |
3731 | |
3732 | ObjType = getSubobjectType( |
3733 | ObjType, ObjType->castAs<ComplexType>()->getElementType()); |
3734 | |
3735 | assert(I == N - 1 && "extracting subobject of scalar?")((void)0); |
3736 | if (O->isComplexInt()) { |
3737 | return handler.found(Index ? O->getComplexIntImag() |
3738 | : O->getComplexIntReal(), ObjType); |
3739 | } else { |
3740 | assert(O->isComplexFloat())((void)0); |
3741 | return handler.found(Index ? O->getComplexFloatImag() |
3742 | : O->getComplexFloatReal(), ObjType); |
3743 | } |
3744 | } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { |
3745 | if (Field->isMutable() && |
3746 | !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) { |
3747 | Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) |
3748 | << handler.AccessKind << Field; |
3749 | Info.Note(Field->getLocation(), diag::note_declared_at); |
3750 | return handler.failed(); |
3751 | } |
3752 | |
3753 | // Next subobject is a class, struct or union field. |
3754 | RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); |
3755 | if (RD->isUnion()) { |
3756 | const FieldDecl *UnionField = O->getUnionField(); |
3757 | if (!UnionField || |
3758 | UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { |
3759 | if (I == N - 1 && handler.AccessKind == AK_Construct) { |
3760 | // Placement new onto an inactive union member makes it active. |
3761 | O->setUnion(Field, APValue()); |
3762 | } else { |
3763 | // FIXME: If O->getUnionValue() is absent, report that there's no |
3764 | // active union member rather than reporting the prior active union |
3765 | // member. We'll need to fix nullptr_t to not use APValue() as its |
3766 | // representation first. |
3767 | Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member) |
3768 | << handler.AccessKind << Field << !UnionField << UnionField; |
3769 | return handler.failed(); |
3770 | } |
3771 | } |
3772 | O = &O->getUnionValue(); |
3773 | } else |
3774 | O = &O->getStructField(Field->getFieldIndex()); |
3775 | |
3776 | ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable()); |
3777 | LastField = Field; |
3778 | if (Field->getType().isVolatileQualified()) |
3779 | VolatileField = Field; |
3780 | } else { |
3781 | // Next subobject is a base class. |
3782 | const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); |
3783 | const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); |
3784 | O = &O->getStructBase(getBaseIndex(Derived, Base)); |
3785 | |
3786 | ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base)); |
3787 | } |
3788 | } |
3789 | } |
3790 | |
3791 | namespace { |
3792 | struct ExtractSubobjectHandler { |
3793 | EvalInfo &Info; |
3794 | const Expr *E; |
3795 | APValue &Result; |
3796 | const AccessKinds AccessKind; |
3797 | |
3798 | typedef bool result_type; |
3799 | bool failed() { return false; } |
3800 | bool found(APValue &Subobj, QualType SubobjType) { |
3801 | Result = Subobj; |
3802 | if (AccessKind == AK_ReadObjectRepresentation) |
3803 | return true; |
3804 | return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result); |
3805 | } |
3806 | bool found(APSInt &Value, QualType SubobjType) { |
3807 | Result = APValue(Value); |
3808 | return true; |
3809 | } |
3810 | bool found(APFloat &Value, QualType SubobjType) { |
3811 | Result = APValue(Value); |
3812 | return true; |
3813 | } |
3814 | }; |
3815 | } // end anonymous namespace |
3816 | |
3817 | /// Extract the designated sub-object of an rvalue. |
3818 | static bool extractSubobject(EvalInfo &Info, const Expr *E, |
3819 | const CompleteObject &Obj, |
3820 | const SubobjectDesignator &Sub, APValue &Result, |
3821 | AccessKinds AK = AK_Read) { |
3822 | assert(AK == AK_Read || AK == AK_ReadObjectRepresentation)((void)0); |
3823 | ExtractSubobjectHandler Handler = {Info, E, Result, AK}; |
3824 | return findSubobject(Info, E, Obj, Sub, Handler); |
3825 | } |
3826 | |
3827 | namespace { |
3828 | struct ModifySubobjectHandler { |
3829 | EvalInfo &Info; |
3830 | APValue &NewVal; |
3831 | const Expr *E; |
3832 | |
3833 | typedef bool result_type; |
3834 | static const AccessKinds AccessKind = AK_Assign; |
3835 | |
3836 | bool checkConst(QualType QT) { |
3837 | // Assigning to a const object has undefined behavior. |
3838 | if (QT.isConstQualified()) { |
3839 | Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; |
3840 | return false; |
3841 | } |
3842 | return true; |
3843 | } |
3844 | |
3845 | bool failed() { return false; } |
3846 | bool found(APValue &Subobj, QualType SubobjType) { |
3847 | if (!checkConst(SubobjType)) |
3848 | return false; |
3849 | // We've been given ownership of NewVal, so just swap it in. |
3850 | Subobj.swap(NewVal); |
3851 | return true; |
3852 | } |
3853 | bool found(APSInt &Value, QualType SubobjType) { |
3854 | if (!checkConst(SubobjType)) |
3855 | return false; |
3856 | if (!NewVal.isInt()) { |
3857 | // Maybe trying to write a cast pointer value into a complex? |
3858 | Info.FFDiag(E); |
3859 | return false; |
3860 | } |
3861 | Value = NewVal.getInt(); |
3862 | return true; |
3863 | } |
3864 | bool found(APFloat &Value, QualType SubobjType) { |
3865 | if (!checkConst(SubobjType)) |
3866 | return false; |
3867 | Value = NewVal.getFloat(); |
3868 | return true; |
3869 | } |
3870 | }; |
3871 | } // end anonymous namespace |
3872 | |
3873 | const AccessKinds ModifySubobjectHandler::AccessKind; |
3874 | |
3875 | /// Update the designated sub-object of an rvalue to the given value. |
3876 | static bool modifySubobject(EvalInfo &Info, const Expr *E, |
3877 | const CompleteObject &Obj, |
3878 | const SubobjectDesignator &Sub, |
3879 | APValue &NewVal) { |
3880 | ModifySubobjectHandler Handler = { Info, NewVal, E }; |
3881 | return findSubobject(Info, E, Obj, Sub, Handler); |
3882 | } |
3883 | |
3884 | /// Find the position where two subobject designators diverge, or equivalently |
3885 | /// the length of the common initial subsequence. |
3886 | static unsigned FindDesignatorMismatch(QualType ObjType, |
3887 | const SubobjectDesignator &A, |
3888 | const SubobjectDesignator &B, |
3889 | bool &WasArrayIndex) { |
3890 | unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); |
3891 | for (/**/; I != N; ++I) { |
3892 | if (!ObjType.isNull() && |
3893 | (ObjType->isArrayType() || ObjType->isAnyComplexType())) { |
3894 | // Next subobject is an array element. |
3895 | if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) { |
3896 | WasArrayIndex = true; |
3897 | return I; |
3898 | } |
3899 | if (ObjType->isAnyComplexType()) |
3900 | ObjType = ObjType->castAs<ComplexType>()->getElementType(); |
3901 | else |
3902 | ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); |
3903 | } else { |
3904 | if (A.Entries[I].getAsBaseOrMember() != |
3905 | B.Entries[I].getAsBaseOrMember()) { |
3906 | WasArrayIndex = false; |
3907 | return I; |
3908 | } |
3909 | if (const FieldDecl *FD = getAsField(A.Entries[I])) |
3910 | // Next subobject is a field. |
3911 | ObjType = FD->getType(); |
3912 | else |
3913 | // Next subobject is a base class. |
3914 | ObjType = QualType(); |
3915 | } |
3916 | } |
3917 | WasArrayIndex = false; |
3918 | return I; |
3919 | } |
3920 | |
3921 | /// Determine whether the given subobject designators refer to elements of the |
3922 | /// same array object. |
3923 | static bool AreElementsOfSameArray(QualType ObjType, |
3924 | const SubobjectDesignator &A, |
3925 | const SubobjectDesignator &B) { |
3926 | if (A.Entries.size() != B.Entries.size()) |
3927 | return false; |
3928 | |
3929 | bool IsArray = A.MostDerivedIsArrayElement; |
3930 | if (IsArray && A.MostDerivedPathLength != A.Entries.size()) |
3931 | // A is a subobject of the array element. |
3932 | return false; |
3933 | |
3934 | // If A (and B) designates an array element, the last entry will be the array |
3935 | // index. That doesn't have to match. Otherwise, we're in the 'implicit array |
3936 | // of length 1' case, and the entire path must match. |
3937 | bool WasArrayIndex; |
3938 | unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); |
3939 | return CommonLength >= A.Entries.size() - IsArray; |
3940 | } |
3941 | |
3942 | /// Find the complete object to which an LValue refers. |
3943 | static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, |
3944 | AccessKinds AK, const LValue &LVal, |
3945 | QualType LValType) { |
3946 | if (LVal.InvalidBase) { |
3947 | Info.FFDiag(E); |
3948 | return CompleteObject(); |
3949 | } |
3950 | |
3951 | if (!LVal.Base) { |
3952 | Info.FFDiag(E, diag::note_constexpr_access_null) << AK; |
3953 | return CompleteObject(); |
3954 | } |
3955 | |
3956 | CallStackFrame *Frame = nullptr; |
3957 | unsigned Depth = 0; |
3958 | if (LVal.getLValueCallIndex()) { |
3959 | std::tie(Frame, Depth) = |
3960 | Info.getCallFrameAndDepth(LVal.getLValueCallIndex()); |
3961 | if (!Frame) { |
3962 | Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1) |
3963 | << AK << LVal.Base.is<const ValueDecl*>(); |
3964 | NoteLValueLocation(Info, LVal.Base); |
3965 | return CompleteObject(); |
3966 | } |
3967 | } |
3968 | |
3969 | bool IsAccess = isAnyAccess(AK); |
3970 | |
3971 | // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type |
3972 | // is not a constant expression (even if the object is non-volatile). We also |
3973 | // apply this rule to C++98, in order to conform to the expected 'volatile' |
3974 | // semantics. |
3975 | if (isFormalAccess(AK) && LValType.isVolatileQualified()) { |
3976 | if (Info.getLangOpts().CPlusPlus) |
3977 | Info.FFDiag(E, diag::note_constexpr_access_volatile_type) |
3978 | << AK << LValType; |
3979 | else |
3980 | Info.FFDiag(E); |
3981 | return CompleteObject(); |
3982 | } |
3983 | |
3984 | // Compute value storage location and type of base object. |
3985 | APValue *BaseVal = nullptr; |
3986 | QualType BaseType = getType(LVal.Base); |
3987 | |
3988 | if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl && |
3989 | lifetimeStartedInEvaluation(Info, LVal.Base)) { |
3990 | // This is the object whose initializer we're evaluating, so its lifetime |
3991 | // started in the current evaluation. |
3992 | BaseVal = Info.EvaluatingDeclValue; |
3993 | } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) { |
3994 | // Allow reading from a GUID declaration. |
3995 | if (auto *GD = dyn_cast<MSGuidDecl>(D)) { |
3996 | if (isModification(AK)) { |
3997 | // All the remaining cases do not permit modification of the object. |
3998 | Info.FFDiag(E, diag::note_constexpr_modify_global); |
3999 | return CompleteObject(); |
4000 | } |
4001 | APValue &V = GD->getAsAPValue(); |
4002 | if (V.isAbsent()) { |
4003 | Info.FFDiag(E, diag::note_constexpr_unsupported_layout) |
4004 | << GD->getType(); |
4005 | return CompleteObject(); |
4006 | } |
4007 | return CompleteObject(LVal.Base, &V, GD->getType()); |
4008 | } |
4009 | |
4010 | // Allow reading from template parameter objects. |
4011 | if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) { |
4012 | if (isModification(AK)) { |
4013 | Info.FFDiag(E, diag::note_constexpr_modify_global); |
4014 | return CompleteObject(); |
4015 | } |
4016 | return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()), |
4017 | TPO->getType()); |
4018 | } |
4019 | |
4020 | // In C++98, const, non-volatile integers initialized with ICEs are ICEs. |
4021 | // In C++11, constexpr, non-volatile variables initialized with constant |
4022 | // expressions are constant expressions too. Inside constexpr functions, |
4023 | // parameters are constant expressions even if they're non-const. |
4024 | // In C++1y, objects local to a constant expression (those with a Frame) are |
4025 | // both readable and writable inside constant expressions. |
4026 | // In C, such things can also be folded, although they are not ICEs. |
4027 | const VarDecl *VD = dyn_cast<VarDecl>(D); |
4028 | if (VD) { |
4029 | if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) |
4030 | VD = VDef; |
4031 | } |
4032 | if (!VD || VD->isInvalidDecl()) { |
4033 | Info.FFDiag(E); |
4034 | return CompleteObject(); |
4035 | } |
4036 | |
4037 | bool IsConstant = BaseType.isConstant(Info.Ctx); |
4038 | |
4039 | // Unless we're looking at a local variable or argument in a constexpr call, |
4040 | // the variable we're reading must be const. |
4041 | if (!Frame) { |
4042 | if (IsAccess && isa<ParmVarDecl>(VD)) { |
4043 | // Access of a parameter that's not associated with a frame isn't going |
4044 | // to work out, but we can leave it to evaluateVarDeclInit to provide a |
4045 | // suitable diagnostic. |
4046 | } else if (Info.getLangOpts().CPlusPlus14 && |
4047 | lifetimeStartedInEvaluation(Info, LVal.Base)) { |
4048 | // OK, we can read and modify an object if we're in the process of |
4049 | // evaluating its initializer, because its lifetime began in this |
4050 | // evaluation. |
4051 | } else if (isModification(AK)) { |
4052 | // All the remaining cases do not permit modification of the object. |
4053 | Info.FFDiag(E, diag::note_constexpr_modify_global); |
4054 | return CompleteObject(); |
4055 | } else if (VD->isConstexpr()) { |
4056 | // OK, we can read this variable. |
4057 | } else if (BaseType->isIntegralOrEnumerationType()) { |
4058 | if (!IsConstant) { |
4059 | if (!IsAccess) |
4060 | return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); |
4061 | if (Info.getLangOpts().CPlusPlus) { |
4062 | Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; |
4063 | Info.Note(VD->getLocation(), diag::note_declared_at); |
4064 | } else { |
4065 | Info.FFDiag(E); |
4066 | } |
4067 | return CompleteObject(); |
4068 | } |
4069 | } else if (!IsAccess) { |
4070 | return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); |
4071 | } else if (IsConstant && Info.checkingPotentialConstantExpression() && |
4072 | BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) { |
4073 | // This variable might end up being constexpr. Don't diagnose it yet. |
4074 | } else if (IsConstant) { |
4075 | // Keep evaluating to see what we can do. In particular, we support |
4076 | // folding of const floating-point types, in order to make static const |
4077 | // data members of such types (supported as an extension) more useful. |
4078 | if (Info.getLangOpts().CPlusPlus) { |
4079 | Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11 |
4080 | ? diag::note_constexpr_ltor_non_constexpr |
4081 | : diag::note_constexpr_ltor_non_integral, 1) |
4082 | << VD << BaseType; |
4083 | Info.Note(VD->getLocation(), diag::note_declared_at); |
4084 | } else { |
4085 | Info.CCEDiag(E); |
4086 | } |
4087 | } else { |
4088 | // Never allow reading a non-const value. |
4089 | if (Info.getLangOpts().CPlusPlus) { |
4090 | Info.FFDiag(E, Info.getLangOpts().CPlusPlus11 |
4091 | ? diag::note_constexpr_ltor_non_constexpr |
4092 | : diag::note_constexpr_ltor_non_integral, 1) |
4093 | << VD << BaseType; |
4094 | Info.Note(VD->getLocation(), diag::note_declared_at); |
4095 | } else { |
4096 | Info.FFDiag(E); |
4097 | } |
4098 | return CompleteObject(); |
4099 | } |
4100 | } |
4101 | |
4102 | if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal)) |
4103 | return CompleteObject(); |
4104 | } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) { |
4105 | Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA); |
4106 | if (!Alloc) { |
4107 | Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK; |
4108 | return CompleteObject(); |
4109 | } |
4110 | return CompleteObject(LVal.Base, &(*Alloc)->Value, |
4111 | LVal.Base.getDynamicAllocType()); |
4112 | } else { |
4113 | const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); |
4114 | |
4115 | if (!Frame) { |
4116 | if (const MaterializeTemporaryExpr *MTE = |
4117 | dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) { |
4118 | assert(MTE->getStorageDuration() == SD_Static &&((void)0) |
4119 | "should have a frame for a non-global materialized temporary")((void)0); |
4120 | |
4121 | // C++20 [expr.const]p4: [DR2126] |
4122 | // An object or reference is usable in constant expressions if it is |
4123 | // - a temporary object of non-volatile const-qualified literal type |
4124 | // whose lifetime is extended to that of a variable that is usable |
4125 | // in constant expressions |
4126 | // |
4127 | // C++20 [expr.const]p5: |
4128 | // an lvalue-to-rvalue conversion [is not allowed unless it applies to] |
4129 | // - a non-volatile glvalue that refers to an object that is usable |
4130 | // in constant expressions, or |
4131 | // - a non-volatile glvalue of literal type that refers to a |
4132 | // non-volatile object whose lifetime began within the evaluation |
4133 | // of E; |
4134 | // |
4135 | // C++11 misses the 'began within the evaluation of e' check and |
4136 | // instead allows all temporaries, including things like: |
4137 | // int &&r = 1; |
4138 | // int x = ++r; |
4139 | // constexpr int k = r; |
4140 | // Therefore we use the C++14-onwards rules in C++11 too. |
4141 | // |
4142 | // Note that temporaries whose lifetimes began while evaluating a |
4143 | // variable's constructor are not usable while evaluating the |
4144 | // corresponding destructor, not even if they're of const-qualified |
4145 | // types. |
4146 | if (!MTE->isUsableInConstantExpressions(Info.Ctx) && |
4147 | !lifetimeStartedInEvaluation(Info, LVal.Base)) { |
4148 | if (!IsAccess) |
4149 | return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); |
4150 | Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK; |
4151 | Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); |
4152 | return CompleteObject(); |
4153 | } |
4154 | |
4155 | BaseVal = MTE->getOrCreateValue(false); |
4156 | assert(BaseVal && "got reference to unevaluated temporary")((void)0); |
4157 | } else { |
4158 | if (!IsAccess) |
4159 | return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); |
4160 | APValue Val; |
4161 | LVal.moveInto(Val); |
4162 | Info.FFDiag(E, diag::note_constexpr_access_unreadable_object) |
4163 | << AK |
4164 | << Val.getAsString(Info.Ctx, |
4165 | Info.Ctx.getLValueReferenceType(LValType)); |
4166 | NoteLValueLocation(Info, LVal.Base); |
4167 | return CompleteObject(); |
4168 | } |
4169 | } else { |
4170 | BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion()); |
4171 | assert(BaseVal && "missing value for temporary")((void)0); |
4172 | } |
4173 | } |
4174 | |
4175 | // In C++14, we can't safely access any mutable state when we might be |
4176 | // evaluating after an unmodeled side effect. Parameters are modeled as state |
4177 | // in the caller, but aren't visible once the call returns, so they can be |
4178 | // modified in a speculatively-evaluated call. |
4179 | // |
4180 | // FIXME: Not all local state is mutable. Allow local constant subobjects |
4181 | // to be read here (but take care with 'mutable' fields). |
4182 | unsigned VisibleDepth = Depth; |
4183 | if (llvm::isa_and_nonnull<ParmVarDecl>( |
4184 | LVal.Base.dyn_cast<const ValueDecl *>())) |
4185 | ++VisibleDepth; |
4186 | if ((Frame && Info.getLangOpts().CPlusPlus14 && |
4187 | Info.EvalStatus.HasSideEffects) || |
4188 | (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth)) |
4189 | return CompleteObject(); |
4190 | |
4191 | return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType); |
4192 | } |
4193 | |
4194 | /// Perform an lvalue-to-rvalue conversion on the given glvalue. This |
4195 | /// can also be used for 'lvalue-to-lvalue' conversions for looking up the |
4196 | /// glvalue referred to by an entity of reference type. |
4197 | /// |
4198 | /// \param Info - Information about the ongoing evaluation. |
4199 | /// \param Conv - The expression for which we are performing the conversion. |
4200 | /// Used for diagnostics. |
4201 | /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the |
4202 | /// case of a non-class type). |
4203 | /// \param LVal - The glvalue on which we are attempting to perform this action. |
4204 | /// \param RVal - The produced value will be placed here. |
4205 | /// \param WantObjectRepresentation - If true, we're looking for the object |
4206 | /// representation rather than the value, and in particular, |
4207 | /// there is no requirement that the result be fully initialized. |
4208 | static bool |
4209 | handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type, |
4210 | const LValue &LVal, APValue &RVal, |
4211 | bool WantObjectRepresentation = false) { |
4212 | if (LVal.Designator.Invalid) |
4213 | return false; |
4214 | |
4215 | // Check for special cases where there is no existing APValue to look at. |
4216 | const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); |
4217 | |
4218 | AccessKinds AK = |
4219 | WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read; |
4220 | |
4221 | if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) { |
4222 | if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { |
4223 | // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the |
4224 | // initializer until now for such expressions. Such an expression can't be |
4225 | // an ICE in C, so this only matters for fold. |
4226 | if (Type.isVolatileQualified()) { |
4227 | Info.FFDiag(Conv); |
4228 | return false; |
4229 | } |
4230 | APValue Lit; |
4231 | if (!Evaluate(Lit, Info, CLE->getInitializer())) |
4232 | return false; |
4233 | CompleteObject LitObj(LVal.Base, &Lit, Base->getType()); |
4234 | return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK); |
4235 | } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) { |
4236 | // Special-case character extraction so we don't have to construct an |
4237 | // APValue for the whole string. |
4238 | assert(LVal.Designator.Entries.size() <= 1 &&((void)0) |
4239 | "Can only read characters from string literals")((void)0); |
4240 | if (LVal.Designator.Entries.empty()) { |
4241 | // Fail for now for LValue to RValue conversion of an array. |
4242 | // (This shouldn't show up in C/C++, but it could be triggered by a |
4243 | // weird EvaluateAsRValue call from a tool.) |
4244 | Info.FFDiag(Conv); |
4245 | return false; |
4246 | } |
4247 | if (LVal.Designator.isOnePastTheEnd()) { |
4248 | if (Info.getLangOpts().CPlusPlus11) |
4249 | Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK; |
4250 | else |
4251 | Info.FFDiag(Conv); |
4252 | return false; |
4253 | } |
4254 | uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex(); |
4255 | RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex)); |
4256 | return true; |
4257 | } |
4258 | } |
4259 | |
4260 | CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type); |
4261 | return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK); |
4262 | } |
4263 | |
4264 | /// Perform an assignment of Val to LVal. Takes ownership of Val. |
4265 | static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, |
4266 | QualType LValType, APValue &Val) { |
4267 | if (LVal.Designator.Invalid) |
4268 | return false; |
4269 | |
4270 | if (!Info.getLangOpts().CPlusPlus14) { |
4271 | Info.FFDiag(E); |
4272 | return false; |
4273 | } |
4274 | |
4275 | CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); |
4276 | return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); |
4277 | } |
4278 | |
4279 | namespace { |
4280 | struct CompoundAssignSubobjectHandler { |
4281 | EvalInfo &Info; |
4282 | const CompoundAssignOperator *E; |
4283 | QualType PromotedLHSType; |
4284 | BinaryOperatorKind Opcode; |
4285 | const APValue &RHS; |
4286 | |
4287 | static const AccessKinds AccessKind = AK_Assign; |
4288 | |
4289 | typedef bool result_type; |
4290 | |
4291 | bool checkConst(QualType QT) { |
4292 | // Assigning to a const object has undefined behavior. |
4293 | if (QT.isConstQualified()) { |
4294 | Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; |
4295 | return false; |
4296 | } |
4297 | return true; |
4298 | } |
4299 | |
4300 | bool failed() { return false; } |
4301 | bool found(APValue &Subobj, QualType SubobjType) { |
4302 | switch (Subobj.getKind()) { |
4303 | case APValue::Int: |
4304 | return found(Subobj.getInt(), SubobjType); |
4305 | case APValue::Float: |
4306 | return found(Subobj.getFloat(), SubobjType); |
4307 | case APValue::ComplexInt: |
4308 | case APValue::ComplexFloat: |
4309 | // FIXME: Implement complex compound assignment. |
4310 | Info.FFDiag(E); |
4311 | return false; |
4312 | case APValue::LValue: |
4313 | return foundPointer(Subobj, SubobjType); |
4314 | case APValue::Vector: |
4315 | return foundVector(Subobj, SubobjType); |
4316 | default: |
4317 | // FIXME: can this happen? |
4318 | Info.FFDiag(E); |
4319 | return false; |
4320 | } |
4321 | } |
4322 | |
4323 | bool foundVector(APValue &Value, QualType SubobjType) { |
4324 | if (!checkConst(SubobjType)) |
4325 | return false; |
4326 | |
4327 | if (!SubobjType->isVectorType()) { |
4328 | Info.FFDiag(E); |
4329 | return false; |
4330 | } |
4331 | return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS); |
4332 | } |
4333 | |
4334 | bool found(APSInt &Value, QualType SubobjType) { |
4335 | if (!checkConst(SubobjType)) |
4336 | return false; |
4337 | |
4338 | if (!SubobjType->isIntegerType()) { |
4339 | // We don't support compound assignment on integer-cast-to-pointer |
4340 | // values. |
4341 | Info.FFDiag(E); |
4342 | return false; |
4343 | } |
4344 | |
4345 | if (RHS.isInt()) { |
4346 | APSInt LHS = |
4347 | HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value); |
4348 | if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) |
4349 | return false; |
4350 | Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); |
4351 | return true; |
4352 | } else if (RHS.isFloat()) { |
4353 | const FPOptions FPO = E->getFPFeaturesInEffect( |
4354 | Info.Ctx.getLangOpts()); |
4355 | APFloat FValue(0.0); |
4356 | return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value, |
4357 | PromotedLHSType, FValue) && |
4358 | handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) && |
4359 | HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType, |
4360 | Value); |
4361 | } |
4362 | |
4363 | Info.FFDiag(E); |
4364 | return false; |
4365 | } |
4366 | bool found(APFloat &Value, QualType SubobjType) { |
4367 | return checkConst(SubobjType) && |
4368 | HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, |
4369 | Value) && |
4370 | handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && |
4371 | HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); |
4372 | } |
4373 | bool foundPointer(APValue &Subobj, QualType SubobjType) { |
4374 | if (!checkConst(SubobjType)) |
4375 | return false; |
4376 | |
4377 | QualType PointeeType; |
4378 | if (const PointerType *PT = SubobjType->getAs<PointerType>()) |
4379 | PointeeType = PT->getPointeeType(); |
4380 | |
4381 | if (PointeeType.isNull() || !RHS.isInt() || |
4382 | (Opcode != BO_Add && Opcode != BO_Sub)) { |
4383 | Info.FFDiag(E); |
4384 | return false; |
4385 | } |
4386 | |
4387 | APSInt Offset = RHS.getInt(); |
4388 | if (Opcode == BO_Sub) |
4389 | negateAsSigned(Offset); |
4390 | |
4391 | LValue LVal; |
4392 | LVal.setFrom(Info.Ctx, Subobj); |
4393 | if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) |
4394 | return false; |
4395 | LVal.moveInto(Subobj); |
4396 | return true; |
4397 | } |
4398 | }; |
4399 | } // end anonymous namespace |
4400 | |
4401 | const AccessKinds CompoundAssignSubobjectHandler::AccessKind; |
4402 | |
4403 | /// Perform a compound assignment of LVal <op>= RVal. |
4404 | static bool handleCompoundAssignment(EvalInfo &Info, |
4405 | const CompoundAssignOperator *E, |
4406 | const LValue &LVal, QualType LValType, |
4407 | QualType PromotedLValType, |
4408 | BinaryOperatorKind Opcode, |
4409 | const APValue &RVal) { |
4410 | if (LVal.Designator.Invalid) |
4411 | return false; |
4412 | |
4413 | if (!Info.getLangOpts().CPlusPlus14) { |
4414 | Info.FFDiag(E); |
4415 | return false; |
4416 | } |
4417 | |
4418 | CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); |
4419 | CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, |
4420 | RVal }; |
4421 | return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); |
4422 | } |
4423 | |
4424 | namespace { |
4425 | struct IncDecSubobjectHandler { |
4426 | EvalInfo &Info; |
4427 | const UnaryOperator *E; |
4428 | AccessKinds AccessKind; |
4429 | APValue *Old; |
4430 | |
4431 | typedef bool result_type; |
4432 | |
4433 | bool checkConst(QualType QT) { |
4434 | // Assigning to a const object has undefined behavior. |
4435 | if (QT.isConstQualified()) { |
4436 | Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; |
4437 | return false; |
4438 | } |
4439 | return true; |
4440 | } |
4441 | |
4442 | bool failed() { return false; } |
4443 | bool found(APValue &Subobj, QualType SubobjType) { |
4444 | // Stash the old value. Also clear Old, so we don't clobber it later |
4445 | // if we're post-incrementing a complex. |
4446 | if (Old) { |
4447 | *Old = Subobj; |
4448 | Old = nullptr; |
4449 | } |
4450 | |
4451 | switch (Subobj.getKind()) { |
4452 | case APValue::Int: |
4453 | return found(Subobj.getInt(), SubobjType); |
4454 | case APValue::Float: |
4455 | return found(Subobj.getFloat(), SubobjType); |
4456 | case APValue::ComplexInt: |
4457 | return found(Subobj.getComplexIntReal(), |
4458 | SubobjType->castAs<ComplexType>()->getElementType() |
4459 | .withCVRQualifiers(SubobjType.getCVRQualifiers())); |
4460 | case APValue::ComplexFloat: |
4461 | return found(Subobj.getComplexFloatReal(), |
4462 | SubobjType->castAs<ComplexType>()->getElementType() |
4463 | .withCVRQualifiers(SubobjType.getCVRQualifiers())); |
4464 | case APValue::LValue: |
4465 | return foundPointer(Subobj, SubobjType); |
4466 | default: |
4467 | // FIXME: can this happen? |
4468 | Info.FFDiag(E); |
4469 | return false; |
4470 | } |
4471 | } |
4472 | bool found(APSInt &Value, QualType SubobjType) { |
4473 | if (!checkConst(SubobjType)) |
4474 | return false; |
4475 | |
4476 | if (!SubobjType->isIntegerType()) { |
4477 | // We don't support increment / decrement on integer-cast-to-pointer |
4478 | // values. |
4479 | Info.FFDiag(E); |
4480 | return false; |
4481 | } |
4482 | |
4483 | if (Old) *Old = APValue(Value); |
4484 | |
4485 | // bool arithmetic promotes to int, and the conversion back to bool |
4486 | // doesn't reduce mod 2^n, so special-case it. |
4487 | if (SubobjType->isBooleanType()) { |
4488 | if (AccessKind == AK_Increment) |
4489 | Value = 1; |
4490 | else |
4491 | Value = !Value; |
4492 | return true; |
4493 | } |
4494 | |
4495 | bool WasNegative = Value.isNegative(); |
4496 | if (AccessKind == AK_Increment) { |
4497 | ++Value; |
4498 | |
4499 | if (!WasNegative && Value.isNegative() && E->canOverflow()) { |
4500 | APSInt ActualValue(Value, /*IsUnsigned*/true); |
4501 | return HandleOverflow(Info, E, ActualValue, SubobjType); |
4502 | } |
4503 | } else { |
4504 | --Value; |
4505 | |
4506 | if (WasNegative && !Value.isNegative() && E->canOverflow()) { |
4507 | unsigned BitWidth = Value.getBitWidth(); |
4508 | APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); |
4509 | ActualValue.setBit(BitWidth); |
4510 | return HandleOverflow(Info, E, ActualValue, SubobjType); |
4511 | } |
4512 | } |
4513 | return true; |
4514 | } |
4515 | bool found(APFloat &Value, QualType SubobjType) { |
4516 | if (!checkConst(SubobjType)) |
4517 | return false; |
4518 | |
4519 | if (Old) *Old = APValue(Value); |
4520 | |
4521 | APFloat One(Value.getSemantics(), 1); |
4522 | if (AccessKind == AK_Increment) |
4523 | Value.add(One, APFloat::rmNearestTiesToEven); |
4524 | else |
4525 | Value.subtract(One, APFloat::rmNearestTiesToEven); |
4526 | return true; |
4527 | } |
4528 | bool foundPointer(APValue &Subobj, QualType SubobjType) { |
4529 | if (!checkConst(SubobjType)) |
4530 | return false; |
4531 | |
4532 | QualType PointeeType; |
4533 | if (const PointerType *PT = SubobjType->getAs<PointerType>()) |
4534 | PointeeType = PT->getPointeeType(); |
4535 | else { |
4536 | Info.FFDiag(E); |
4537 | return false; |
4538 | } |
4539 | |
4540 | LValue LVal; |
4541 | LVal.setFrom(Info.Ctx, Subobj); |
4542 | if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, |
4543 | AccessKind == AK_Increment ? 1 : -1)) |
4544 | return false; |
4545 | LVal.moveInto(Subobj); |
4546 | return true; |
4547 | } |
4548 | }; |
4549 | } // end anonymous namespace |
4550 | |
4551 | /// Perform an increment or decrement on LVal. |
4552 | static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, |
4553 | QualType LValType, bool IsIncrement, APValue *Old) { |
4554 | if (LVal.Designator.Invalid) |
4555 | return false; |
4556 | |
4557 | if (!Info.getLangOpts().CPlusPlus14) { |
4558 | Info.FFDiag(E); |
4559 | return false; |
4560 | } |
4561 | |
4562 | AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; |
4563 | CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); |
4564 | IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old}; |
4565 | return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); |
4566 | } |
4567 | |
4568 | /// Build an lvalue for the object argument of a member function call. |
4569 | static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, |
4570 | LValue &This) { |
4571 | if (Object->getType()->isPointerType() && Object->isPRValue()) |
4572 | return EvaluatePointer(Object, This, Info); |
4573 | |
4574 | if (Object->isGLValue()) |
4575 | return EvaluateLValue(Object, This, Info); |
4576 | |
4577 | if (Object->getType()->isLiteralType(Info.Ctx)) |
4578 | return EvaluateTemporary(Object, This, Info); |
4579 | |
4580 | Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType(); |
4581 | return false; |
4582 | } |
4583 | |
4584 | /// HandleMemberPointerAccess - Evaluate a member access operation and build an |
4585 | /// lvalue referring to the result. |
4586 | /// |
4587 | /// \param Info - Information about the ongoing evaluation. |
4588 | /// \param LV - An lvalue referring to the base of the member pointer. |
4589 | /// \param RHS - The member pointer expression. |
4590 | /// \param IncludeMember - Specifies whether the member itself is included in |
4591 | /// the resulting LValue subobject designator. This is not possible when |
4592 | /// creating a bound member function. |
4593 | /// \return The field or method declaration to which the member pointer refers, |
4594 | /// or 0 if evaluation fails. |
4595 | static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, |
4596 | QualType LVType, |
4597 | LValue &LV, |
4598 | const Expr *RHS, |
4599 | bool IncludeMember = true) { |
4600 | MemberPtr MemPtr; |
4601 | if (!EvaluateMemberPointer(RHS, MemPtr, Info)) |
4602 | return nullptr; |
4603 | |
4604 | // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to |
4605 | // member value, the behavior is undefined. |
4606 | if (!MemPtr.getDecl()) { |
4607 | // FIXME: Specific diagnostic. |
4608 | Info.FFDiag(RHS); |
4609 | return nullptr; |
4610 | } |
4611 | |
4612 | if (MemPtr.isDerivedMember()) { |
4613 | // This is a member of some derived class. Truncate LV appropriately. |
4614 | // The end of the derived-to-base path for the base object must match the |
4615 | // derived-to-base path for the member pointer. |
4616 | if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > |
4617 | LV.Designator.Entries.size()) { |
4618 | Info.FFDiag(RHS); |
4619 | return nullptr; |
4620 | } |
4621 | unsigned PathLengthToMember = |
4622 | LV.Designator.Entries.size() - MemPtr.Path.size(); |
4623 | for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { |
4624 | const CXXRecordDecl *LVDecl = getAsBaseClass( |
4625 | LV.Designator.Entries[PathLengthToMember + I]); |
4626 | const CXXRecordDecl *MPDecl = MemPtr.Path[I]; |
4627 | if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { |
4628 | Info.FFDiag(RHS); |
4629 | return nullptr; |
4630 | } |
4631 | } |
4632 | |
4633 | // Truncate the lvalue to the appropriate derived class. |
4634 | if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), |
4635 | PathLengthToMember)) |
4636 | return nullptr; |
4637 | } else if (!MemPtr.Path.empty()) { |
4638 | // Extend the LValue path with the member pointer's path. |
4639 | LV.Designator.Entries.reserve(LV.Designator.Entries.size() + |
4640 | MemPtr.Path.size() + IncludeMember); |
4641 | |
4642 | // Walk down to the appropriate base class. |
4643 | if (const PointerType *PT = LVType->getAs<PointerType>()) |
4644 | LVType = PT->getPointeeType(); |
4645 | const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); |
4646 | assert(RD && "member pointer access on non-class-type expression")((void)0); |
4647 | // The first class in the path is that of the lvalue. |
4648 | for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { |
4649 | const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; |
4650 | if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) |
4651 | return nullptr; |
4652 | RD = Base; |
4653 | } |
4654 | // Finally cast to the class containing the member. |
4655 | if (!HandleLValueDirectBase(Info, RHS, LV, RD, |
4656 | MemPtr.getContainingRecord())) |
4657 | return nullptr; |
4658 | } |
4659 | |
4660 | // Add the member. Note that we cannot build bound member functions here. |
4661 | if (IncludeMember) { |
4662 | if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { |
4663 | if (!HandleLValueMember(Info, RHS, LV, FD)) |
4664 | return nullptr; |
4665 | } else if (const IndirectFieldDecl *IFD = |
4666 | dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { |
4667 | if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) |
4668 | return nullptr; |
4669 | } else { |
4670 | llvm_unreachable("can't construct reference to bound member function")__builtin_unreachable(); |
4671 | } |
4672 | } |
4673 | |
4674 | return MemPtr.getDecl(); |
4675 | } |
4676 | |
4677 | static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, |
4678 | const BinaryOperator *BO, |
4679 | LValue &LV, |
4680 | bool IncludeMember = true) { |
4681 | assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI)((void)0); |
4682 | |
4683 | if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { |
4684 | if (Info.noteFailure()) { |
4685 | MemberPtr MemPtr; |
4686 | EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); |
4687 | } |
4688 | return nullptr; |
4689 | } |
4690 | |
4691 | return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, |
4692 | BO->getRHS(), IncludeMember); |
4693 | } |
4694 | |
4695 | /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on |
4696 | /// the provided lvalue, which currently refers to the base object. |
4697 | static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, |
4698 | LValue &Result) { |
4699 | SubobjectDesignator &D = Result.Designator; |
4700 | if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) |
4701 | return false; |
4702 | |
4703 | QualType TargetQT = E->getType(); |
4704 | if (const PointerType *PT = TargetQT->getAs<PointerType>()) |
4705 | TargetQT = PT->getPointeeType(); |
4706 | |
4707 | // Check this cast lands within the final derived-to-base subobject path. |
4708 | if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { |
4709 | Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) |
4710 | << D.MostDerivedType << TargetQT; |
4711 | return false; |
4712 | } |
4713 | |
4714 | // Check the type of the final cast. We don't need to check the path, |
4715 | // since a cast can only be formed if the path is unique. |
4716 | unsigned NewEntriesSize = D.Entries.size() - E->path_size(); |
4717 | const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); |
4718 | const CXXRecordDecl *FinalType; |
4719 | if (NewEntriesSize == D.MostDerivedPathLength) |
4720 | FinalType = D.MostDerivedType->getAsCXXRecordDecl(); |
4721 | else |
4722 | FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); |
4723 | if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { |
4724 | Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) |
4725 | << D.MostDerivedType << TargetQT; |
4726 | return false; |
4727 | } |
4728 | |
4729 | // Truncate the lvalue to the appropriate derived class. |
4730 | return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); |
4731 | } |
4732 | |
4733 | /// Get the value to use for a default-initialized object of type T. |
4734 | /// Return false if it encounters something invalid. |
4735 | static bool getDefaultInitValue(QualType T, APValue &Result) { |
4736 | bool Success = true; |
4737 | if (auto *RD = T->getAsCXXRecordDecl()) { |
4738 | if (RD->isInvalidDecl()) { |
4739 | Result = APValue(); |
4740 | return false; |
4741 | } |
4742 | if (RD->isUnion()) { |
4743 | Result = APValue((const FieldDecl *)nullptr); |
4744 | return true; |
4745 | } |
4746 | Result = APValue(APValue::UninitStruct(), RD->getNumBases(), |
4747 | std::distance(RD->field_begin(), RD->field_end())); |
4748 | |
4749 | unsigned Index = 0; |
4750 | for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
4751 | End = RD->bases_end(); |
4752 | I != End; ++I, ++Index) |
4753 | Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index)); |
4754 | |
4755 | for (const auto *I : RD->fields()) { |
4756 | if (I->isUnnamedBitfield()) |
4757 | continue; |
4758 | Success &= getDefaultInitValue(I->getType(), |
4759 | Result.getStructField(I->getFieldIndex())); |
4760 | } |
4761 | return Success; |
4762 | } |
4763 | |
4764 | if (auto *AT = |
4765 | dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) { |
4766 | Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue()); |
4767 | if (Result.hasArrayFiller()) |
4768 | Success &= |
4769 | getDefaultInitValue(AT->getElementType(), Result.getArrayFiller()); |
4770 | |
4771 | return Success; |
4772 | } |
4773 | |
4774 | Result = APValue::IndeterminateValue(); |
4775 | return true; |
4776 | } |
4777 | |
4778 | namespace { |
4779 | enum EvalStmtResult { |
4780 | /// Evaluation failed. |
4781 | ESR_Failed, |
4782 | /// Hit a 'return' statement. |
4783 | ESR_Returned, |
4784 | /// Evaluation succeeded. |
4785 | ESR_Succeeded, |
4786 | /// Hit a 'continue' statement. |
4787 | ESR_Continue, |
4788 | /// Hit a 'break' statement. |
4789 | ESR_Break, |
4790 | /// Still scanning for 'case' or 'default' statement. |
4791 | ESR_CaseNotFound |
4792 | }; |
4793 | } |
4794 | |
4795 | static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) { |
4796 | // We don't need to evaluate the initializer for a static local. |
4797 | if (!VD->hasLocalStorage()) |
4798 | return true; |
4799 | |
4800 | LValue Result; |
4801 | APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(), |
4802 | ScopeKind::Block, Result); |
4803 | |
4804 | const Expr *InitE = VD->getInit(); |
4805 | if (!InitE) { |
4806 | if (VD->getType()->isDependentType()) |
4807 | return Info.noteSideEffect(); |
4808 | return getDefaultInitValue(VD->getType(), Val); |
4809 | } |
4810 | if (InitE->isValueDependent()) |
4811 | return false; |
4812 | |
4813 | if (!EvaluateInPlace(Val, Info, Result, InitE)) { |
4814 | // Wipe out any partially-computed value, to allow tracking that this |
4815 | // evaluation failed. |
4816 | Val = APValue(); |
4817 | return false; |
4818 | } |
4819 | |
4820 | return true; |
4821 | } |
4822 | |
4823 | static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { |
4824 | bool OK = true; |
4825 | |
4826 | if (const VarDecl *VD = dyn_cast<VarDecl>(D)) |
4827 | OK &= EvaluateVarDecl(Info, VD); |
4828 | |
4829 | if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D)) |
4830 | for (auto *BD : DD->bindings()) |
4831 | if (auto *VD = BD->getHoldingVar()) |
4832 | OK &= EvaluateDecl(Info, VD); |
4833 | |
4834 | return OK; |
4835 | } |
4836 | |
4837 | static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) { |
4838 | assert(E->isValueDependent())((void)0); |
4839 | if (Info.noteSideEffect()) |
4840 | return true; |
4841 | assert(E->containsErrors() && "valid value-dependent expression should never "((void)0) |
4842 | "reach invalid code path.")((void)0); |
4843 | return false; |
4844 | } |
4845 | |
4846 | /// Evaluate a condition (either a variable declaration or an expression). |
4847 | static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, |
4848 | const Expr *Cond, bool &Result) { |
4849 | if (Cond->isValueDependent()) |
4850 | return false; |
4851 | FullExpressionRAII Scope(Info); |
4852 | if (CondDecl && !EvaluateDecl(Info, CondDecl)) |
4853 | return false; |
4854 | if (!EvaluateAsBooleanCondition(Cond, Result, Info)) |
4855 | return false; |
4856 | return Scope.destroy(); |
4857 | } |
4858 | |
4859 | namespace { |
4860 | /// A location where the result (returned value) of evaluating a |
4861 | /// statement should be stored. |
4862 | struct StmtResult { |
4863 | /// The APValue that should be filled in with the returned value. |
4864 | APValue &Value; |
4865 | /// The location containing the result, if any (used to support RVO). |
4866 | const LValue *Slot; |
4867 | }; |
4868 | |
4869 | struct TempVersionRAII { |
4870 | CallStackFrame &Frame; |
4871 | |
4872 | TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) { |
4873 | Frame.pushTempVersion(); |
4874 | } |
4875 | |
4876 | ~TempVersionRAII() { |
4877 | Frame.popTempVersion(); |
4878 | } |
4879 | }; |
4880 | |
4881 | } |
4882 | |
4883 | static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, |
4884 | const Stmt *S, |
4885 | const SwitchCase *SC = nullptr); |
4886 | |
4887 | /// Evaluate the body of a loop, and translate the result as appropriate. |
4888 | static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info, |
4889 | const Stmt *Body, |
4890 | const SwitchCase *Case = nullptr) { |
4891 | BlockScopeRAII Scope(Info); |
4892 | |
4893 | EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case); |
4894 | if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy()) |
4895 | ESR = ESR_Failed; |
4896 | |
4897 | switch (ESR) { |
4898 | case ESR_Break: |
4899 | return ESR_Succeeded; |
4900 | case ESR_Succeeded: |
4901 | case ESR_Continue: |
4902 | return ESR_Continue; |
4903 | case ESR_Failed: |
4904 | case ESR_Returned: |
4905 | case ESR_CaseNotFound: |
4906 | return ESR; |
4907 | } |
4908 | llvm_unreachable("Invalid EvalStmtResult!")__builtin_unreachable(); |
4909 | } |
4910 | |
4911 | /// Evaluate a switch statement. |
4912 | static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info, |
4913 | const SwitchStmt *SS) { |
4914 | BlockScopeRAII Scope(Info); |
4915 | |
4916 | // Evaluate the switch condition. |
4917 | APSInt Value; |
4918 | { |
4919 | if (const Stmt *Init = SS->getInit()) { |
4920 | EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); |
4921 | if (ESR != ESR_Succeeded) { |
4922 | if (ESR != ESR_Failed && !Scope.destroy()) |
4923 | ESR = ESR_Failed; |
4924 | return ESR; |
4925 | } |
4926 | } |
4927 | |
4928 | FullExpressionRAII CondScope(Info); |
4929 | if (SS->getConditionVariable() && |
4930 | !EvaluateDecl(Info, SS->getConditionVariable())) |
4931 | return ESR_Failed; |
4932 | if (!EvaluateInteger(SS->getCond(), Value, Info)) |
4933 | return ESR_Failed; |
4934 | if (!CondScope.destroy()) |
4935 | return ESR_Failed; |
4936 | } |
4937 | |
4938 | // Find the switch case corresponding to the value of the condition. |
4939 | // FIXME: Cache this lookup. |
4940 | const SwitchCase *Found = nullptr; |
4941 | for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; |
4942 | SC = SC->getNextSwitchCase()) { |
4943 | if (isa<DefaultStmt>(SC)) { |
4944 | Found = SC; |
4945 | continue; |
4946 | } |
4947 | |
4948 | const CaseStmt *CS = cast<CaseStmt>(SC); |
4949 | APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); |
4950 | APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) |
4951 | : LHS; |
4952 | if (LHS <= Value && Value <= RHS) { |
4953 | Found = SC; |
4954 | break; |
4955 | } |
4956 | } |
4957 | |
4958 | if (!Found) |
4959 | return Scope.destroy() ? ESR_Succeeded : ESR_Failed; |
4960 | |
4961 | // Search the switch body for the switch case and evaluate it from there. |
4962 | EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found); |
4963 | if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy()) |
4964 | return ESR_Failed; |
4965 | |
4966 | switch (ESR) { |
4967 | case ESR_Break: |
4968 | return ESR_Succeeded; |
4969 | case ESR_Succeeded: |
4970 | case ESR_Continue: |
4971 | case ESR_Failed: |
4972 | case ESR_Returned: |
4973 | return ESR; |
4974 | case ESR_CaseNotFound: |
4975 | // This can only happen if the switch case is nested within a statement |
4976 | // expression. We have no intention of supporting that. |
4977 | Info.FFDiag(Found->getBeginLoc(), |
4978 | diag::note_constexpr_stmt_expr_unsupported); |
4979 | return ESR_Failed; |
4980 | } |
4981 | llvm_unreachable("Invalid EvalStmtResult!")__builtin_unreachable(); |
4982 | } |
4983 | |
4984 | // Evaluate a statement. |
4985 | static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, |
4986 | const Stmt *S, const SwitchCase *Case) { |
4987 | if (!Info.nextStep(S)) |
4988 | return ESR_Failed; |
4989 | |
4990 | // If we're hunting down a 'case' or 'default' label, recurse through |
4991 | // substatements until we hit the label. |
4992 | if (Case) { |
4993 | switch (S->getStmtClass()) { |
4994 | case Stmt::CompoundStmtClass: |
4995 | // FIXME: Precompute which substatement of a compound statement we |
4996 | // would jump to, and go straight there rather than performing a |
4997 | // linear scan each time. |
4998 | case Stmt::LabelStmtClass: |
4999 | case Stmt::AttributedStmtClass: |
5000 | case Stmt::DoStmtClass: |
5001 | break; |
5002 | |
5003 | case Stmt::CaseStmtClass: |
5004 | case Stmt::DefaultStmtClass: |
5005 | if (Case == S) |
5006 | Case = nullptr; |
5007 | break; |
5008 | |
5009 | case Stmt::IfStmtClass: { |
5010 | // FIXME: Precompute which side of an 'if' we would jump to, and go |
5011 | // straight there rather than scanning both sides. |
5012 | const IfStmt *IS = cast<IfStmt>(S); |
5013 | |
5014 | // Wrap the evaluation in a block scope, in case it's a DeclStmt |
5015 | // preceded by our switch label. |
5016 | BlockScopeRAII Scope(Info); |
5017 | |
5018 | // Step into the init statement in case it brings an (uninitialized) |
5019 | // variable into scope. |
5020 | if (const Stmt *Init = IS->getInit()) { |
5021 | EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case); |
5022 | if (ESR != ESR_CaseNotFound) { |
5023 | assert(ESR != ESR_Succeeded)((void)0); |
5024 | return ESR; |
5025 | } |
5026 | } |
5027 | |
5028 | // Condition variable must be initialized if it exists. |
5029 | // FIXME: We can skip evaluating the body if there's a condition |
5030 | // variable, as there can't be any case labels within it. |
5031 | // (The same is true for 'for' statements.) |
5032 | |
5033 | EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); |
5034 | if (ESR == ESR_Failed) |
5035 | return ESR; |
5036 | if (ESR != ESR_CaseNotFound) |
5037 | return Scope.destroy() ? ESR : ESR_Failed; |
5038 | if (!IS->getElse()) |
5039 | return ESR_CaseNotFound; |
5040 | |
5041 | ESR = EvaluateStmt(Result, Info, IS->getElse(), Case); |
5042 | if (ESR == ESR_Failed) |
5043 | return ESR; |
5044 | if (ESR != ESR_CaseNotFound) |
5045 | return Scope.destroy() ? ESR : ESR_Failed; |
5046 | return ESR_CaseNotFound; |
5047 | } |
5048 | |
5049 | case Stmt::WhileStmtClass: { |
5050 | EvalStmtResult ESR = |
5051 | EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); |
5052 | if (ESR != ESR_Continue) |
5053 | return ESR; |
5054 | break; |
5055 | } |
5056 | |
5057 | case Stmt::ForStmtClass: { |
5058 | const ForStmt *FS = cast<ForStmt>(S); |
5059 | BlockScopeRAII Scope(Info); |
5060 | |
5061 | // Step into the init statement in case it brings an (uninitialized) |
5062 | // variable into scope. |
5063 | if (const Stmt *Init = FS->getInit()) { |
5064 | EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case); |
5065 | if (ESR != ESR_CaseNotFound) { |
5066 | assert(ESR != ESR_Succeeded)((void)0); |
5067 | return ESR; |
5068 | } |
5069 | } |
5070 | |
5071 | EvalStmtResult ESR = |
5072 | EvaluateLoopBody(Result, Info, FS->getBody(), Case); |
5073 | if (ESR != ESR_Continue) |
5074 | return ESR; |
5075 | if (const auto *Inc = FS->getInc()) { |
5076 | if (Inc->isValueDependent()) { |
5077 | if (!EvaluateDependentExpr(Inc, Info)) |
5078 | return ESR_Failed; |
5079 | } else { |
5080 | FullExpressionRAII IncScope(Info); |
5081 | if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy()) |
5082 | return ESR_Failed; |
5083 | } |
5084 | } |
5085 | break; |
5086 | } |
5087 | |
5088 | case Stmt::DeclStmtClass: { |
5089 | // Start the lifetime of any uninitialized variables we encounter. They |
5090 | // might be used by the selected branch of the switch. |
5091 | const DeclStmt *DS = cast<DeclStmt>(S); |
5092 | for (const auto *D : DS->decls()) { |
5093 | if (const auto *VD = dyn_cast<VarDecl>(D)) { |
5094 | if (VD->hasLocalStorage() && !VD->getInit()) |
5095 | if (!EvaluateVarDecl(Info, VD)) |
5096 | return ESR_Failed; |
5097 | // FIXME: If the variable has initialization that can't be jumped |
5098 | // over, bail out of any immediately-surrounding compound-statement |
5099 | // too. There can't be any case labels here. |
5100 | } |
5101 | } |
5102 | return ESR_CaseNotFound; |
5103 | } |
5104 | |
5105 | default: |
5106 | return ESR_CaseNotFound; |
5107 | } |
5108 | } |
5109 | |
5110 | switch (S->getStmtClass()) { |
5111 | default: |
5112 | if (const Expr *E = dyn_cast<Expr>(S)) { |
5113 | if (E->isValueDependent()) { |
5114 | if (!EvaluateDependentExpr(E, Info)) |
5115 | return ESR_Failed; |
5116 | } else { |
5117 | // Don't bother evaluating beyond an expression-statement which couldn't |
5118 | // be evaluated. |
5119 | // FIXME: Do we need the FullExpressionRAII object here? |
5120 | // VisitExprWithCleanups should create one when necessary. |
5121 | FullExpressionRAII Scope(Info); |
5122 | if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy()) |
5123 | return ESR_Failed; |
5124 | } |
5125 | return ESR_Succeeded; |
5126 | } |
5127 | |
5128 | Info.FFDiag(S->getBeginLoc()); |
5129 | return ESR_Failed; |
5130 | |
5131 | case Stmt::NullStmtClass: |
5132 | return ESR_Succeeded; |
5133 | |
5134 | case Stmt::DeclStmtClass: { |
5135 | const DeclStmt *DS = cast<DeclStmt>(S); |
5136 | for (const auto *D : DS->decls()) { |
5137 | // Each declaration initialization is its own full-expression. |
5138 | FullExpressionRAII Scope(Info); |
5139 | if (!EvaluateDecl(Info, D) && !Info.noteFailure()) |
5140 | return ESR_Failed; |
5141 | if (!Scope.destroy()) |
5142 | return ESR_Failed; |
5143 | } |
5144 | return ESR_Succeeded; |
5145 | } |
5146 | |
5147 | case Stmt::ReturnStmtClass: { |
5148 | const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); |
5149 | FullExpressionRAII Scope(Info); |
5150 | if (RetExpr && RetExpr->isValueDependent()) { |
5151 | EvaluateDependentExpr(RetExpr, Info); |
5152 | // We know we returned, but we don't know what the value is. |
5153 | return ESR_Failed; |
5154 | } |
5155 | if (RetExpr && |
5156 | !(Result.Slot |
5157 | ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr) |
5158 | : Evaluate(Result.Value, Info, RetExpr))) |
5159 | return ESR_Failed; |
5160 | return Scope.destroy() ? ESR_Returned : ESR_Failed; |
5161 | } |
5162 | |
5163 | case Stmt::CompoundStmtClass: { |
5164 | BlockScopeRAII Scope(Info); |
5165 | |
5166 | const CompoundStmt *CS = cast<CompoundStmt>(S); |
5167 | for (const auto *BI : CS->body()) { |
5168 | EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); |
5169 | if (ESR == ESR_Succeeded) |
5170 | Case = nullptr; |
5171 | else if (ESR != ESR_CaseNotFound) { |
5172 | if (ESR != ESR_Failed && !Scope.destroy()) |
5173 | return ESR_Failed; |
5174 | return ESR; |
5175 | } |
5176 | } |
5177 | if (Case) |
5178 | return ESR_CaseNotFound; |
5179 | return Scope.destroy() ? ESR_Succeeded : ESR_Failed; |
5180 | } |
5181 | |
5182 | case Stmt::IfStmtClass: { |
5183 | const IfStmt *IS = cast<IfStmt>(S); |
5184 | |
5185 | // Evaluate the condition, as either a var decl or as an expression. |
5186 | BlockScopeRAII Scope(Info); |
5187 | if (const Stmt *Init = IS->getInit()) { |
5188 | EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); |
5189 | if (ESR != ESR_Succeeded) { |
5190 | if (ESR != ESR_Failed && !Scope.destroy()) |
5191 | return ESR_Failed; |
5192 | return ESR; |
5193 | } |
5194 | } |
5195 | bool Cond; |
5196 | if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) |
5197 | return ESR_Failed; |
5198 | |
5199 | if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { |
5200 | EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); |
5201 | if (ESR != ESR_Succeeded) { |
5202 | if (ESR != ESR_Failed && !Scope.destroy()) |
5203 | return ESR_Failed; |
5204 | return ESR; |
5205 | } |
5206 | } |
5207 | return Scope.destroy() ? ESR_Succeeded : ESR_Failed; |
5208 | } |
5209 | |
5210 | case Stmt::WhileStmtClass: { |
5211 | const WhileStmt *WS = cast<WhileStmt>(S); |
5212 | while (true) { |
5213 | BlockScopeRAII Scope(Info); |
5214 | bool Continue; |
5215 | if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), |
5216 | Continue)) |
5217 | return ESR_Failed; |
5218 | if (!Continue) |
5219 | break; |
5220 | |
5221 | EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); |
5222 | if (ESR != ESR_Continue) { |
5223 | if (ESR != ESR_Failed && !Scope.destroy()) |
5224 | return ESR_Failed; |
5225 | return ESR; |
5226 | } |
5227 | if (!Scope.destroy()) |
5228 | return ESR_Failed; |
5229 | } |
5230 | return ESR_Succeeded; |
5231 | } |
5232 | |
5233 | case Stmt::DoStmtClass: { |
5234 | const DoStmt *DS = cast<DoStmt>(S); |
5235 | bool Continue; |
5236 | do { |
5237 | EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); |
5238 | if (ESR != ESR_Continue) |
5239 | return ESR; |
5240 | Case = nullptr; |
5241 | |
5242 | if (DS->getCond()->isValueDependent()) { |
5243 | EvaluateDependentExpr(DS->getCond(), Info); |
5244 | // Bailout as we don't know whether to keep going or terminate the loop. |
5245 | return ESR_Failed; |
5246 | } |
5247 | FullExpressionRAII CondScope(Info); |
5248 | if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) || |
5249 | !CondScope.destroy()) |
5250 | return ESR_Failed; |
5251 | } while (Continue); |
5252 | return ESR_Succeeded; |
5253 | } |
5254 | |
5255 | case Stmt::ForStmtClass: { |
5256 | const ForStmt *FS = cast<ForStmt>(S); |
5257 | BlockScopeRAII ForScope(Info); |
5258 | if (FS->getInit()) { |
5259 | EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); |
5260 | if (ESR != ESR_Succeeded) { |
5261 | if (ESR != ESR_Failed && !ForScope.destroy()) |
5262 | return ESR_Failed; |
5263 | return ESR; |
5264 | } |
5265 | } |
5266 | while (true) { |
5267 | BlockScopeRAII IterScope(Info); |
5268 | bool Continue = true; |
5269 | if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), |
5270 | FS->getCond(), Continue)) |
5271 | return ESR_Failed; |
5272 | if (!Continue) |
5273 | break; |
5274 | |
5275 | EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); |
5276 | if (ESR != ESR_Continue) { |
5277 | if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy())) |
5278 | return ESR_Failed; |
5279 | return ESR; |
5280 | } |
5281 | |
5282 | if (const auto *Inc = FS->getInc()) { |
5283 | if (Inc->isValueDependent()) { |
5284 | if (!EvaluateDependentExpr(Inc, Info)) |
5285 | return ESR_Failed; |
5286 | } else { |
5287 | FullExpressionRAII IncScope(Info); |
5288 | if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy()) |
5289 | return ESR_Failed; |
5290 | } |
5291 | } |
5292 | |
5293 | if (!IterScope.destroy()) |
5294 | return ESR_Failed; |
5295 | } |
5296 | return ForScope.destroy() ? ESR_Succeeded : ESR_Failed; |
5297 | } |
5298 | |
5299 | case Stmt::CXXForRangeStmtClass: { |
5300 | const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); |
5301 | BlockScopeRAII Scope(Info); |
5302 | |
5303 | // Evaluate the init-statement if present. |
5304 | if (FS->getInit()) { |
5305 | EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); |
5306 | if (ESR != ESR_Succeeded) { |
5307 | if (ESR != ESR_Failed && !Scope.destroy()) |
5308 | return ESR_Failed; |
5309 | return ESR; |
5310 | } |
5311 | } |
5312 | |
5313 | // Initialize the __range variable. |
5314 | EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); |
5315 | if (ESR != ESR_Succeeded) { |
5316 | if (ESR != ESR_Failed && !Scope.destroy()) |
5317 | return ESR_Failed; |
5318 | return ESR; |
5319 | } |
5320 | |
5321 | // Create the __begin and __end iterators. |
5322 | ESR = EvaluateStmt(Result, Info, FS->getBeginStmt()); |
5323 | if (ESR != ESR_Succeeded) { |
5324 | if (ESR != ESR_Failed && !Scope.destroy()) |
5325 | return ESR_Failed; |
5326 | return ESR; |
5327 | } |
5328 | ESR = EvaluateStmt(Result, Info, FS->getEndStmt()); |
5329 | if (ESR != ESR_Succeeded) { |
5330 | if (ESR != ESR_Failed && !Scope.destroy()) |
5331 | return ESR_Failed; |
5332 | return ESR; |
5333 | } |
5334 | |
5335 | while (true) { |
5336 | // Condition: __begin != __end. |
5337 | { |
5338 | if (FS->getCond()->isValueDependent()) { |
5339 | EvaluateDependentExpr(FS->getCond(), Info); |
5340 | // We don't know whether to keep going or terminate the loop. |
5341 | return ESR_Failed; |
5342 | } |
5343 | bool Continue = true; |
5344 | FullExpressionRAII CondExpr(Info); |
5345 | if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) |
5346 | return ESR_Failed; |
5347 | if (!Continue) |
5348 | break; |
5349 | } |
5350 | |
5351 | // User's variable declaration, initialized by *__begin. |
5352 | BlockScopeRAII InnerScope(Info); |
5353 | ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); |
5354 | if (ESR != ESR_Succeeded) { |
5355 | if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy())) |
5356 | return ESR_Failed; |
5357 | return ESR; |
5358 | } |
5359 | |
5360 | // Loop body. |
5361 | ESR = EvaluateLoopBody(Result, Info, FS->getBody()); |
5362 | if (ESR != ESR_Continue) { |
5363 | if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy())) |
5364 | return ESR_Failed; |
5365 | return ESR; |
5366 | } |
5367 | if (FS->getInc()->isValueDependent()) { |
5368 | if (!EvaluateDependentExpr(FS->getInc(), Info)) |
5369 | return ESR_Failed; |
5370 | } else { |
5371 | // Increment: ++__begin |
5372 | if (!EvaluateIgnoredValue(Info, FS->getInc())) |
5373 | return ESR_Failed; |
5374 | } |
5375 | |
5376 | if (!InnerScope.destroy()) |
5377 | return ESR_Failed; |
5378 | } |
5379 | |
5380 | return Scope.destroy() ? ESR_Succeeded : ESR_Failed; |
5381 | } |
5382 | |
5383 | case Stmt::SwitchStmtClass: |
5384 | return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); |
5385 | |
5386 | case Stmt::ContinueStmtClass: |
5387 | return ESR_Continue; |
5388 | |
5389 | case Stmt::BreakStmtClass: |
5390 | return ESR_Break; |
5391 | |
5392 | case Stmt::LabelStmtClass: |
5393 | return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); |
5394 | |
5395 | case Stmt::AttributedStmtClass: |
5396 | // As a general principle, C++11 attributes can be ignored without |
5397 | // any semantic impact. |
5398 | return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), |
5399 | Case); |
5400 | |
5401 | case Stmt::CaseStmtClass: |
5402 | case Stmt::DefaultStmtClass: |
5403 | return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); |
5404 | case Stmt::CXXTryStmtClass: |
5405 | // Evaluate try blocks by evaluating all sub statements. |
5406 | return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case); |
5407 | } |
5408 | } |
5409 | |
5410 | /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial |
5411 | /// default constructor. If so, we'll fold it whether or not it's marked as |
5412 | /// constexpr. If it is marked as constexpr, we will never implicitly define it, |
5413 | /// so we need special handling. |
5414 | static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, |
5415 | const CXXConstructorDecl *CD, |
5416 | bool IsValueInitialization) { |
5417 | if (!CD->isTrivial() || !CD->isDefaultConstructor()) |
5418 | return false; |
5419 | |
5420 | // Value-initialization does not call a trivial default constructor, so such a |
5421 | // call is a core constant expression whether or not the constructor is |
5422 | // constexpr. |
5423 | if (!CD->isConstexpr() && !IsValueInitialization) { |
5424 | if (Info.getLangOpts().CPlusPlus11) { |
5425 | // FIXME: If DiagDecl is an implicitly-declared special member function, |
5426 | // we should be much more explicit about why it's not constexpr. |
5427 | Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) |
5428 | << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; |
5429 | Info.Note(CD->getLocation(), diag::note_declared_at); |
5430 | } else { |
5431 | Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); |
5432 | } |
5433 | } |
5434 | return true; |
5435 | } |
5436 | |
5437 | /// CheckConstexprFunction - Check that a function can be called in a constant |
5438 | /// expression. |
5439 | static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, |
5440 | const FunctionDecl *Declaration, |
5441 | const FunctionDecl *Definition, |
5442 | const Stmt *Body) { |
5443 | // Potential constant expressions can contain calls to declared, but not yet |
5444 | // defined, constexpr functions. |
5445 | if (Info.checkingPotentialConstantExpression() && !Definition && |
5446 | Declaration->isConstexpr()) |
5447 | return false; |
5448 | |
5449 | // Bail out if the function declaration itself is invalid. We will |
5450 | // have produced a relevant diagnostic while parsing it, so just |
5451 | // note the problematic sub-expression. |
5452 | if (Declaration->isInvalidDecl()) { |
5453 | Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); |
5454 | return false; |
5455 | } |
5456 | |
5457 | // DR1872: An instantiated virtual constexpr function can't be called in a |
5458 | // constant expression (prior to C++20). We can still constant-fold such a |
5459 | // call. |
5460 | if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) && |
5461 | cast<CXXMethodDecl>(Declaration)->isVirtual()) |
5462 | Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call); |
5463 | |
5464 | if (Definition && Definition->isInvalidDecl()) { |
5465 | Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); |
5466 | return false; |
5467 | } |
5468 | |
5469 | // Can we evaluate this function call? |
5470 | if (Definition && Definition->isConstexpr() && Body) |
5471 | return true; |
5472 | |
5473 | if (Info.getLangOpts().CPlusPlus11) { |
5474 | const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; |
5475 | |
5476 | // If this function is not constexpr because it is an inherited |
5477 | // non-constexpr constructor, diagnose that directly. |
5478 | auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl); |
5479 | if (CD && CD->isInheritingConstructor()) { |
5480 | auto *Inherited = CD->getInheritedConstructor().getConstructor(); |
5481 | if (!Inherited->isConstexpr()) |
5482 | DiagDecl = CD = Inherited; |
5483 | } |
5484 | |
5485 | // FIXME: If DiagDecl is an implicitly-declared special member function |
5486 | // or an inheriting constructor, we should be much more explicit about why |
5487 | // it's not constexpr. |
5488 | if (CD && CD->isInheritingConstructor()) |
5489 | Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1) |
5490 | << CD->getInheritedConstructor().getConstructor()->getParent(); |
5491 | else |
5492 | Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1) |
5493 | << DiagDecl->isConstexpr() << (bool)CD << DiagDecl; |
5494 | Info.Note(DiagDecl->getLocation(), diag::note_declared_at); |
5495 | } else { |
5496 | Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); |
5497 | } |
5498 | return false; |
5499 | } |
5500 | |
5501 | namespace { |
5502 | struct CheckDynamicTypeHandler { |
5503 | AccessKinds AccessKind; |
5504 | typedef bool result_type; |
5505 | bool failed() { return false; } |
5506 | bool found(APValue &Subobj, QualType SubobjType) { return true; } |
5507 | bool found(APSInt &Value, QualType SubobjType) { return true; } |
5508 | bool found(APFloat &Value, QualType SubobjType) { return true; } |
5509 | }; |
5510 | } // end anonymous namespace |
5511 | |
5512 | /// Check that we can access the notional vptr of an object / determine its |
5513 | /// dynamic type. |
5514 | static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This, |
5515 | AccessKinds AK, bool Polymorphic) { |
5516 | if (This.Designator.Invalid) |
5517 | return false; |
5518 | |
5519 | CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType()); |
5520 | |
5521 | if (!Obj) |
5522 | return false; |
5523 | |
5524 | if (!Obj.Value) { |
5525 | // The object is not usable in constant expressions, so we can't inspect |
5526 | // its value to see if it's in-lifetime or what the active union members |
5527 | // are. We can still check for a one-past-the-end lvalue. |
5528 | if (This.Designator.isOnePastTheEnd() || |
5529 | This.Designator.isMostDerivedAnUnsizedArray()) { |
5530 | Info.FFDiag(E, This.Designator.isOnePastTheEnd() |
5531 | ? diag::note_constexpr_access_past_end |
5532 | : diag::note_constexpr_access_unsized_array) |
5533 | << AK; |
5534 | return false; |
5535 | } else if (Polymorphic) { |
5536 | // Conservatively refuse to perform a polymorphic operation if we would |
5537 | // not be able to read a notional 'vptr' value. |
5538 | APValue Val; |
5539 | This.moveInto(Val); |
5540 | QualType StarThisType = |
5541 | Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx)); |
5542 | Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type) |
5543 | << AK << Val.getAsString(Info.Ctx, StarThisType); |
5544 | return false; |
5545 | } |
5546 | return true; |
5547 | } |
5548 | |
5549 | CheckDynamicTypeHandler Handler{AK}; |
5550 | return Obj && findSubobject(Info, E, Obj, This.Designator, Handler); |
5551 | } |
5552 | |
5553 | /// Check that the pointee of the 'this' pointer in a member function call is |
5554 | /// either within its lifetime or in its period of construction or destruction. |
5555 | static bool |
5556 | checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E, |
5557 | const LValue &This, |
5558 | const CXXMethodDecl *NamedMember) { |
5559 | return checkDynamicType( |
5560 | Info, E, This, |
5561 | isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false); |
5562 | } |
5563 | |
5564 | struct DynamicType { |
5565 | /// The dynamic class type of the object. |
5566 | const CXXRecordDecl *Type; |
5567 | /// The corresponding path length in the lvalue. |
5568 | unsigned PathLength; |
5569 | }; |
5570 | |
5571 | static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator, |
5572 | unsigned PathLength) { |
5573 | assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=((void)0) |
5574 | Designator.Entries.size() && "invalid path length")((void)0); |
5575 | return (PathLength == Designator.MostDerivedPathLength) |
5576 | ? Designator.MostDerivedType->getAsCXXRecordDecl() |
5577 | : getAsBaseClass(Designator.Entries[PathLength - 1]); |
5578 | } |
5579 | |
5580 | /// Determine the dynamic type of an object. |
5581 | static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E, |
5582 | LValue &This, AccessKinds AK) { |
5583 | // If we don't have an lvalue denoting an object of class type, there is no |
5584 | // meaningful dynamic type. (We consider objects of non-class type to have no |
5585 | // dynamic type.) |
5586 | if (!checkDynamicType(Info, E, This, AK, true)) |
5587 | return None; |
5588 | |
5589 | // Refuse to compute a dynamic type in the presence of virtual bases. This |
5590 | // shouldn't happen other than in constant-folding situations, since literal |
5591 | // types can't have virtual bases. |
5592 | // |
5593 | // Note that consumers of DynamicType assume that the type has no virtual |
5594 | // bases, and will need modifications if this restriction is relaxed. |
5595 | const CXXRecordDecl *Class = |
5596 | This.Designator.MostDerivedType->getAsCXXRecordDecl(); |
5597 | if (!Class || Class->getNumVBases()) { |
5598 | Info.FFDiag(E); |
5599 | return None; |
5600 | } |
5601 | |
5602 | // FIXME: For very deep class hierarchies, it might be beneficial to use a |
5603 | // binary search here instead. But the overwhelmingly common case is that |
5604 | // we're not in the middle of a constructor, so it probably doesn't matter |
5605 | // in practice. |
5606 | ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries; |
5607 | for (unsigned PathLength = This.Designator.MostDerivedPathLength; |
5608 | PathLength <= Path.size(); ++PathLength) { |
5609 | switch (Info.isEvaluatingCtorDtor(This.getLValueBase(), |
5610 | Path.slice(0, PathLength))) { |
5611 | case ConstructionPhase::Bases: |
5612 | case ConstructionPhase::DestroyingBases: |
5613 | // We're constructing or destroying a base class. This is not the dynamic |
5614 | // type. |
5615 | break; |
5616 | |
5617 | case ConstructionPhase::None: |
5618 | case ConstructionPhase::AfterBases: |
5619 | case ConstructionPhase::AfterFields: |
5620 | case ConstructionPhase::Destroying: |
5621 | // We've finished constructing the base classes and not yet started |
5622 | // destroying them again, so this is the dynamic type. |
5623 | return DynamicType{getBaseClassType(This.Designator, PathLength), |
5624 | PathLength}; |
5625 | } |
5626 | } |
5627 | |
5628 | // CWG issue 1517: we're constructing a base class of the object described by |
5629 | // 'This', so that object has not yet begun its period of construction and |
5630 | // any polymorphic operation on it results in undefined behavior. |
5631 | Info.FFDiag(E); |
5632 | return None; |
5633 | } |
5634 | |
5635 | /// Perform virtual dispatch. |
5636 | static const CXXMethodDecl *HandleVirtualDispatch( |
5637 | EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found, |
5638 | llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) { |
5639 | Optional<DynamicType> DynType = ComputeDynamicType( |
5640 | Info, E, This, |
5641 | isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall); |
5642 | if (!DynType) |
5643 | return nullptr; |
5644 | |
5645 | // Find the final overrider. It must be declared in one of the classes on the |
5646 | // path from the dynamic type to the static type. |
5647 | // FIXME: If we ever allow literal types to have virtual base classes, that |
5648 | // won't be true. |
5649 | const CXXMethodDecl *Callee = Found; |
5650 | unsigned PathLength = DynType->PathLength; |
5651 | for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) { |
5652 | const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength); |
5653 | const CXXMethodDecl *Overrider = |
5654 | Found->getCorrespondingMethodDeclaredInClass(Class, false); |
5655 | if (Overrider) { |
5656 | Callee = Overrider; |
5657 | break; |
5658 | } |
5659 | } |
5660 | |
5661 | // C++2a [class.abstract]p6: |
5662 | // the effect of making a virtual call to a pure virtual function [...] is |
5663 | // undefined |
5664 | if (Callee->isPure()) { |
5665 | Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee; |
5666 | Info.Note(Callee->getLocation(), diag::note_declared_at); |
5667 | return nullptr; |
5668 | } |
5669 | |
5670 | // If necessary, walk the rest of the path to determine the sequence of |
5671 | // covariant adjustment steps to apply. |
5672 | if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(), |
5673 | Found->getReturnType())) { |
5674 | CovariantAdjustmentPath.push_back(Callee->getReturnType()); |
5675 | for (unsigned CovariantPathLength = PathLength + 1; |
5676 | CovariantPathLength != This.Designator.Entries.size(); |
5677 | ++CovariantPathLength) { |
5678 | const CXXRecordDecl *NextClass = |
5679 | getBaseClassType(This.Designator, CovariantPathLength); |
5680 | const CXXMethodDecl *Next = |
5681 | Found->getCorrespondingMethodDeclaredInClass(NextClass, false); |
5682 | if (Next && !Info.Ctx.hasSameUnqualifiedType( |
5683 | Next->getReturnType(), CovariantAdjustmentPath.back())) |
5684 | CovariantAdjustmentPath.push_back(Next->getReturnType()); |
5685 | } |
5686 | if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(), |
5687 | CovariantAdjustmentPath.back())) |
5688 | CovariantAdjustmentPath.push_back(Found->getReturnType()); |
5689 | } |
5690 | |
5691 | // Perform 'this' adjustment. |
5692 | if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength)) |
5693 | return nullptr; |
5694 | |
5695 | return Callee; |
5696 | } |
5697 | |
5698 | /// Perform the adjustment from a value returned by a virtual function to |
5699 | /// a value of the statically expected type, which may be a pointer or |
5700 | /// reference to a base class of the returned type. |
5701 | static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E, |
5702 | APValue &Result, |
5703 | ArrayRef<QualType> Path) { |
5704 | assert(Result.isLValue() &&((void)0) |
5705 | "unexpected kind of APValue for covariant return")((void)0); |
5706 | if (Result.isNullPointer()) |
5707 | return true; |
5708 | |
5709 | LValue LVal; |
5710 | LVal.setFrom(Info.Ctx, Result); |
5711 | |
5712 | const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl(); |
5713 | for (unsigned I = 1; I != Path.size(); ++I) { |
5714 | const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl(); |
5715 | assert(OldClass && NewClass && "unexpected kind of covariant return")((void)0); |
5716 | if (OldClass != NewClass && |
5717 | !CastToBaseClass(Info, E, LVal, OldClass, NewClass)) |
5718 | return false; |
5719 | OldClass = NewClass; |
5720 | } |
5721 | |
5722 | LVal.moveInto(Result); |
5723 | return true; |
5724 | } |
5725 | |
5726 | /// Determine whether \p Base, which is known to be a direct base class of |
5727 | /// \p Derived, is a public base class. |
5728 | static bool isBaseClassPublic(const CXXRecordDecl *Derived, |
5729 | const CXXRecordDecl *Base) { |
5730 | for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) { |
5731 | auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl(); |
5732 | if (BaseClass && declaresSameEntity(BaseClass, Base)) |
5733 | return BaseSpec.getAccessSpecifier() == AS_public; |
5734 | } |
5735 | llvm_unreachable("Base is not a direct base of Derived")__builtin_unreachable(); |
5736 | } |
5737 | |
5738 | /// Apply the given dynamic cast operation on the provided lvalue. |
5739 | /// |
5740 | /// This implements the hard case of dynamic_cast, requiring a "runtime check" |
5741 | /// to find a suitable target subobject. |
5742 | static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E, |
5743 | LValue &Ptr) { |
5744 | // We can't do anything with a non-symbolic pointer value. |
5745 | SubobjectDesignator &D = Ptr.Designator; |
5746 | if (D.Invalid) |
5747 | return false; |
5748 | |
5749 | // C++ [expr.dynamic.cast]p6: |
5750 | // If v is a null pointer value, the result is a null pointer value. |
5751 | if (Ptr.isNullPointer() && !E->isGLValue()) |
5752 | return true; |
5753 | |
5754 | // For all the other cases, we need the pointer to point to an object within |
5755 | // its lifetime / period of construction / destruction, and we need to know |
5756 | // its dynamic type. |
5757 | Optional<DynamicType> DynType = |
5758 | ComputeDynamicType(Info, E, Ptr, AK_DynamicCast); |
5759 | if (!DynType) |
5760 | return false; |
5761 | |
5762 | // C++ [expr.dynamic.cast]p7: |
5763 | // If T is "pointer to cv void", then the result is a pointer to the most |
5764 | // derived object |
5765 | if (E->getType()->isVoidPointerType()) |
5766 | return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength); |
5767 | |
5768 | const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl(); |
5769 | assert(C && "dynamic_cast target is not void pointer nor class")((void)0); |
5770 | CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C)); |
5771 | |
5772 | auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) { |
5773 | // C++ [expr.dynamic.cast]p9: |
5774 | if (!E->isGLValue()) { |
5775 | // The value of a failed cast to pointer type is the null pointer value |
5776 | // of the required result type. |
5777 | Ptr.setNull(Info.Ctx, E->getType()); |
5778 | return true; |
5779 | } |
5780 | |
5781 | // A failed cast to reference type throws [...] std::bad_cast. |
5782 | unsigned DiagKind; |
5783 | if (!Paths && (declaresSameEntity(DynType->Type, C) || |
5784 | DynType->Type->isDerivedFrom(C))) |
5785 | DiagKind = 0; |
5786 | else if (!Paths || Paths->begin() == Paths->end()) |
5787 | DiagKind = 1; |
5788 | else if (Paths->isAmbiguous(CQT)) |
5789 | DiagKind = 2; |
5790 | else { |
5791 | assert(Paths->front().Access != AS_public && "why did the cast fail?")((void)0); |
5792 | DiagKind = 3; |
5793 | } |
5794 | Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed) |
5795 | << DiagKind << Ptr.Designator.getType(Info.Ctx) |
5796 | << Info.Ctx.getRecordType(DynType->Type) |
5797 | << E->getType().getUnqualifiedType(); |
5798 | return false; |
5799 | }; |
5800 | |
5801 | // Runtime check, phase 1: |
5802 | // Walk from the base subobject towards the derived object looking for the |
5803 | // target type. |
5804 | for (int PathLength = Ptr.Designator.Entries.size(); |
5805 | PathLength >= (int)DynType->PathLength; --PathLength) { |
5806 | const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength); |
5807 | if (declaresSameEntity(Class, C)) |
5808 | return CastToDerivedClass(Info, E, Ptr, Class, PathLength); |
5809 | // We can only walk across public inheritance edges. |
5810 | if (PathLength > (int)DynType->PathLength && |
5811 | !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1), |
5812 | Class)) |
5813 | return RuntimeCheckFailed(nullptr); |
5814 | } |
5815 | |
5816 | // Runtime check, phase 2: |
5817 | // Search the dynamic type for an unambiguous public base of type C. |
5818 | CXXBasePaths Paths(/*FindAmbiguities=*/true, |
5819 | /*RecordPaths=*/true, /*DetectVirtual=*/false); |
5820 | if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) && |
5821 | Paths.front().Access == AS_public) { |
5822 | // Downcast to the dynamic type... |
5823 | if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength)) |
5824 | return false; |
5825 | // ... then upcast to the chosen base class subobject. |
5826 | for (CXXBasePathElement &Elem : Paths.front()) |
5827 | if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base)) |
5828 | return false; |
5829 | return true; |
5830 | } |
5831 | |
5832 | // Otherwise, the runtime check fails. |
5833 | return RuntimeCheckFailed(&Paths); |
5834 | } |
5835 | |
5836 | namespace { |
5837 | struct StartLifetimeOfUnionMemberHandler { |
5838 | EvalInfo &Info; |
5839 | const Expr *LHSExpr; |
5840 | const FieldDecl *Field; |
5841 | bool DuringInit; |
5842 | bool Failed = false; |
5843 | static const AccessKinds AccessKind = AK_Assign; |
5844 | |
5845 | typedef bool result_type; |
5846 | bool failed() { return Failed; } |
5847 | bool found(APValue &Subobj, QualType SubobjType) { |
5848 | // We are supposed to perform no initialization but begin the lifetime of |
5849 | // the object. We interpret that as meaning to do what default |
5850 | // initialization of the object would do if all constructors involved were |
5851 | // trivial: |
5852 | // * All base, non-variant member, and array element subobjects' lifetimes |
5853 | // begin |
5854 | // * No variant members' lifetimes begin |
5855 | // * All scalar subobjects whose lifetimes begin have indeterminate values |
5856 | assert(SubobjType->isUnionType())((void)0); |
5857 | if (declaresSameEntity(Subobj.getUnionField(), Field)) { |
5858 | // This union member is already active. If it's also in-lifetime, there's |
5859 | // nothing to do. |
5860 | if (Subobj.getUnionValue().hasValue()) |
5861 | return true; |
5862 | } else if (DuringInit) { |
5863 | // We're currently in the process of initializing a different union |
5864 | // member. If we carried on, that initialization would attempt to |
5865 | // store to an inactive union member, resulting in undefined behavior. |
5866 | Info.FFDiag(LHSExpr, |
5867 | diag::note_constexpr_union_member_change_during_init); |
5868 | return false; |
5869 | } |
5870 | APValue Result; |
5871 | Failed = !getDefaultInitValue(Field->getType(), Result); |
5872 | Subobj.setUnion(Field, Result); |
5873 | return true; |
5874 | } |
5875 | bool found(APSInt &Value, QualType SubobjType) { |
5876 | llvm_unreachable("wrong value kind for union object")__builtin_unreachable(); |
5877 | } |
5878 | bool found(APFloat &Value, QualType SubobjType) { |
5879 | llvm_unreachable("wrong value kind for union object")__builtin_unreachable(); |
5880 | } |
5881 | }; |
5882 | } // end anonymous namespace |
5883 | |
5884 | const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind; |
5885 | |
5886 | /// Handle a builtin simple-assignment or a call to a trivial assignment |
5887 | /// operator whose left-hand side might involve a union member access. If it |
5888 | /// does, implicitly start the lifetime of any accessed union elements per |
5889 | /// C++20 [class.union]5. |
5890 | static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr, |
5891 | const LValue &LHS) { |
5892 | if (LHS.InvalidBase || LHS.Designator.Invalid) |
5893 | return false; |
5894 | |
5895 | llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths; |
5896 | // C++ [class.union]p5: |
5897 | // define the set S(E) of subexpressions of E as follows: |
5898 | unsigned PathLength = LHS.Designator.Entries.size(); |
5899 | for (const Expr *E = LHSExpr; E != nullptr;) { |
5900 | // -- If E is of the form A.B, S(E) contains the elements of S(A)... |
5901 | if (auto *ME = dyn_cast<MemberExpr>(E)) { |
5902 | auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()); |
5903 | // Note that we can't implicitly start the lifetime of a reference, |
5904 | // so we don't need to proceed any further if we reach one. |
5905 | if (!FD || FD->getType()->isReferenceType()) |
5906 | break; |
5907 | |
5908 | // ... and also contains A.B if B names a union member ... |
5909 | if (FD->getParent()->isUnion()) { |
5910 | // ... of a non-class, non-array type, or of a class type with a |
5911 | // trivial default constructor that is not deleted, or an array of |
5912 | // such types. |
5913 | auto *RD = |
5914 | FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); |
5915 | if (!RD || RD->hasTrivialDefaultConstructor()) |
5916 | UnionPathLengths.push_back({PathLength - 1, FD}); |
5917 | } |
5918 | |
5919 | E = ME->getBase(); |
5920 | --PathLength; |
5921 | assert(declaresSameEntity(FD,((void)0) |
5922 | LHS.Designator.Entries[PathLength]((void)0) |
5923 | .getAsBaseOrMember().getPointer()))((void)0); |
5924 | |
5925 | // -- If E is of the form A[B] and is interpreted as a built-in array |
5926 | // subscripting operator, S(E) is [S(the array operand, if any)]. |
5927 | } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) { |
5928 | // Step over an ArrayToPointerDecay implicit cast. |
5929 | auto *Base = ASE->getBase()->IgnoreImplicit(); |
5930 | if (!Base->getType()->isArrayType()) |
5931 | break; |
5932 | |
5933 | E = Base; |
5934 | --PathLength; |
5935 | |
5936 | } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) { |
5937 | // Step over a derived-to-base conversion. |
5938 | E = ICE->getSubExpr(); |
5939 | if (ICE->getCastKind() == CK_NoOp) |
5940 | continue; |
5941 | if (ICE->getCastKind() != CK_DerivedToBase && |
5942 | ICE->getCastKind() != CK_UncheckedDerivedToBase) |
5943 | break; |
5944 | // Walk path backwards as we walk up from the base to the derived class. |
5945 | for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) { |
5946 | --PathLength; |
5947 | (void)Elt; |
5948 | assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),((void)0) |
5949 | LHS.Designator.Entries[PathLength]((void)0) |
5950 | .getAsBaseOrMember().getPointer()))((void)0); |
5951 | } |
5952 | |
5953 | // -- Otherwise, S(E) is empty. |
5954 | } else { |
5955 | break; |
5956 | } |
5957 | } |
5958 | |
5959 | // Common case: no unions' lifetimes are started. |
5960 | if (UnionPathLengths.empty()) |
5961 | return true; |
5962 | |
5963 | // if modification of X [would access an inactive union member], an object |
5964 | // of the type of X is implicitly created |
5965 | CompleteObject Obj = |
5966 | findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType()); |
5967 | if (!Obj) |
5968 | return false; |
5969 | for (std::pair<unsigned, const FieldDecl *> LengthAndField : |
5970 | llvm::reverse(UnionPathLengths)) { |
5971 | // Form a designator for the union object. |
5972 | SubobjectDesignator D = LHS.Designator; |
5973 | D.truncate(Info.Ctx, LHS.Base, LengthAndField.first); |
5974 | |
5975 | bool DuringInit = Info.isEvaluatingCtorDtor(LHS.Base, D.Entries) == |
5976 | ConstructionPhase::AfterBases; |
5977 | StartLifetimeOfUnionMemberHandler StartLifetime{ |
5978 | Info, LHSExpr, LengthAndField.second, DuringInit}; |
5979 | if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime)) |
5980 | return false; |
5981 | } |
5982 | |
5983 | return true; |
5984 | } |
5985 | |
5986 | static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg, |
5987 | CallRef Call, EvalInfo &Info, |
5988 | bool NonNull = false) { |
5989 | LValue LV; |
5990 | // Create the parameter slot and register its destruction. For a vararg |
5991 | // argument, create a temporary. |
5992 | // FIXME: For calling conventions that destroy parameters in the callee, |
5993 | // should we consider performing destruction when the function returns |
5994 | // instead? |
5995 | APValue &V = PVD ? Info.CurrentCall->createParam(Call, PVD, LV) |
5996 | : Info.CurrentCall->createTemporary(Arg, Arg->getType(), |
5997 | ScopeKind::Call, LV); |
5998 | if (!EvaluateInPlace(V, Info, LV, Arg)) |
5999 | return false; |
6000 | |
6001 | // Passing a null pointer to an __attribute__((nonnull)) parameter results in |
6002 | // undefined behavior, so is non-constant. |
6003 | if (NonNull && V.isLValue() && V.isNullPointer()) { |
6004 | Info.CCEDiag(Arg, diag::note_non_null_attribute_failed); |
6005 | return false; |
6006 | } |
6007 | |
6008 | return true; |
6009 | } |
6010 | |
6011 | /// Evaluate the arguments to a function call. |
6012 | static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call, |
6013 | EvalInfo &Info, const FunctionDecl *Callee, |
6014 | bool RightToLeft = false) { |
6015 | bool Success = true; |
6016 | llvm::SmallBitVector ForbiddenNullArgs; |
6017 | if (Callee->hasAttr<NonNullAttr>()) { |
6018 | ForbiddenNullArgs.resize(Args.size()); |
6019 | for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) { |
6020 | if (!Attr->args_size()) { |
6021 | ForbiddenNullArgs.set(); |
6022 | break; |
6023 | } else |
6024 | for (auto Idx : Attr->args()) { |
6025 | unsigned ASTIdx = Idx.getASTIndex(); |
6026 | if (ASTIdx >= Args.size()) |
6027 | continue; |
6028 | ForbiddenNullArgs[ASTIdx] = 1; |
6029 | } |
6030 | } |
6031 | } |
6032 | for (unsigned I = 0; I < Args.size(); I++) { |
6033 | unsigned Idx = RightToLeft ? Args.size() - I - 1 : I; |
6034 | const ParmVarDecl *PVD = |
6035 | Idx < Callee->getNumParams() ? Callee->getParamDecl(Idx) : nullptr; |
6036 | bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx]; |
6037 | if (!EvaluateCallArg(PVD, Args[Idx], Call, Info, NonNull)) { |
6038 | // If we're checking for a potential constant expression, evaluate all |
6039 | // initializers even if some of them fail. |
6040 | if (!Info.noteFailure()) |
6041 | return false; |
6042 | Success = false; |
6043 | } |
6044 | } |
6045 | return Success; |
6046 | } |
6047 | |
6048 | /// Perform a trivial copy from Param, which is the parameter of a copy or move |
6049 | /// constructor or assignment operator. |
6050 | static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param, |
6051 | const Expr *E, APValue &Result, |
6052 | bool CopyObjectRepresentation) { |
6053 | // Find the reference argument. |
6054 | CallStackFrame *Frame = Info.CurrentCall; |
6055 | APValue *RefValue = Info.getParamSlot(Frame->Arguments, Param); |
6056 | if (!RefValue) { |
6057 | Info.FFDiag(E); |
6058 | return false; |
6059 | } |
6060 | |
6061 | // Copy out the contents of the RHS object. |
6062 | LValue RefLValue; |
6063 | RefLValue.setFrom(Info.Ctx, *RefValue); |
6064 | return handleLValueToRValueConversion( |
6065 | Info, E, Param->getType().getNonReferenceType(), RefLValue, Result, |
6066 | CopyObjectRepresentation); |
6067 | } |
6068 | |
6069 | /// Evaluate a function call. |
6070 | static bool HandleFunctionCall(SourceLocation CallLoc, |
6071 | const FunctionDecl *Callee, const LValue *This, |
6072 | ArrayRef<const Expr *> Args, CallRef Call, |
6073 | const Stmt *Body, EvalInfo &Info, |
6074 | APValue &Result, const LValue *ResultSlot) { |
6075 | if (!Info.CheckCallLimit(CallLoc)) |
6076 | return false; |
6077 | |
6078 | CallStackFrame Frame(Info, CallLoc, Callee, This, Call); |
6079 | |
6080 | // For a trivial copy or move assignment, perform an APValue copy. This is |
6081 | // essential for unions, where the operations performed by the assignment |
6082 | // operator cannot be represented as statements. |
6083 | // |
6084 | // Skip this for non-union classes with no fields; in that case, the defaulted |
6085 | // copy/move does not actually read the object. |
6086 | const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); |
6087 | if (MD && MD->isDefaulted() && |
6088 | (MD->getParent()->isUnion() || |
6089 | (MD->isTrivial() && |
6090 | isReadByLvalueToRvalueConversion(MD->getParent())))) { |
6091 | assert(This &&((void)0) |
6092 | (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()))((void)0); |
6093 | APValue RHSValue; |
6094 | if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue, |
6095 | MD->getParent()->isUnion())) |
6096 | return false; |
6097 | if (Info.getLangOpts().CPlusPlus20 && MD->isTrivial() && |
6098 | !HandleUnionActiveMemberChange(Info, Args[0], *This)) |
6099 | return false; |
6100 |