/usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/llvm/include/llvm/Support/Alignment.h

Bug Summary

File:	src/gnu/usr.bin/clang/libclangAST/../../../llvm/llvm/include/llvm/Support/Alignment.h
Warning:	line 85, column 47 The result of the left shift is undefined due to shifting by '255', which is greater or equal to the width of type 'uint64_t'

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ByteCodeExprGen.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangAST/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libclangAST/obj/../include/clang/AST -I /usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/clang/include -I /usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libclangAST/../include -I /usr/src/gnu/usr.bin/clang/libclangAST/obj -I /usr/src/gnu/usr.bin/clang/libclangAST/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangAST/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/clang/lib/AST/Interp/ByteCodeExprGen.cpp

/usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/clang/lib/AST/Interp/ByteCodeExprGen.cpp

→

1//===--- ByteCodeExprGen.cpp - Code generator for expressions ---*- C++ -*-===//
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//===----------------------------------------------------------------------===//

9#include "ByteCodeExprGen.h"
10#include "ByteCodeEmitter.h"
11#include "ByteCodeGenError.h"
12#include "Context.h"
13#include "Function.h"
14#include "PrimType.h"
15#include "Program.h"
16#include "State.h"

18using namespace clang;
19using namespace clang::interp;

21using APSInt = llvm::APSInt;
22template <typename T> using Expected = llvm::Expected<T>;
23template <typename T> using Optional = llvm::Optional<T>;

25namespace clang {
26namespace interp {

28/// Scope used to handle temporaries in toplevel variable declarations.
29template <class Emitter> class DeclScope final : public LocalScope<Emitter> {
30public:
DeclScope(ByteCodeExprGen<Emitter> *Ctx, const VarDecl *VD)
    : LocalScope<Emitter>(Ctx), Scope(Ctx->P, VD) {}

void addExtended(const Scope::Local &Local) override {
  return this->addLocal(Local);
}

38private:
Program::DeclScope Scope;
40};

42/// Scope used to handle initialization methods.
43template <class Emitter> class OptionScope {
44public:
using InitFnRef = typename ByteCodeExprGen<Emitter>::InitFnRef;
using ChainedInitFnRef = std::function<bool(InitFnRef)>;

/// Root constructor, compiling or discarding primitives.
OptionScope(ByteCodeExprGen<Emitter> *Ctx, bool NewDiscardResult)
    : Ctx(Ctx), OldDiscardResult(Ctx->DiscardResult),
      OldInitFn(std::move(Ctx->InitFn)) {
  Ctx->DiscardResult = NewDiscardResult;
  Ctx->InitFn = llvm::Optional<InitFnRef>{};
}

/// Root constructor, setting up compilation state.
OptionScope(ByteCodeExprGen<Emitter> *Ctx, InitFnRef NewInitFn)
    : Ctx(Ctx), OldDiscardResult(Ctx->DiscardResult),
      OldInitFn(std::move(Ctx->InitFn)) {
  Ctx->DiscardResult = true;
  Ctx->InitFn = NewInitFn;
}

/// Extends the chain of initialisation pointers.
OptionScope(ByteCodeExprGen<Emitter> *Ctx, ChainedInitFnRef NewInitFn)
    : Ctx(Ctx), OldDiscardResult(Ctx->DiscardResult),
      OldInitFn(std::move(Ctx->InitFn)) {
  assert(OldInitFn && "missing initializer")((void)0);
  Ctx->InitFn = [this, NewInitFn] { return NewInitFn(*OldInitFn); };
}

~OptionScope() {
  Ctx->DiscardResult = OldDiscardResult;
  Ctx->InitFn = std::move(OldInitFn);
}

77private:
/// Parent context.
ByteCodeExprGen<Emitter> *Ctx;
/// Old discard flag to restore.
bool OldDiscardResult;
/// Old pointer emitter to restore.
llvm::Optional<InitFnRef> OldInitFn;
84};

86} // namespace interp
87} // namespace clang

89template <class Emitter>
90bool ByteCodeExprGen<Emitter>::VisitCastExpr(const CastExpr *CE) {
auto *SubExpr = CE->getSubExpr();
switch (CE->getCastKind()) {

case CK_LValueToRValue: {
  return dereference(
      CE->getSubExpr(), DerefKind::Read,
      [](PrimType) {
        // Value loaded - nothing to do here.
        return true;
      },
      [this, CE](PrimType T) {
        // Pointer on stack - dereference it.
        if (!this->emitLoadPop(T, CE))
          return false;
        return DiscardResult ? this->emitPop(T, CE) : true;
      });
}

case CK_ArrayToPointerDecay:
case CK_AtomicToNonAtomic:
case CK_ConstructorConversion:
case CK_FunctionToPointerDecay:
case CK_NonAtomicToAtomic:
case CK_NoOp:
case CK_UserDefinedConversion:
  return this->Visit(SubExpr);

case CK_ToVoid:
  return discard(SubExpr);

default: {
  // TODO: implement other casts.
  return this->bail(CE);
}
}
126}

128template <class Emitter>
129bool ByteCodeExprGen<Emitter>::VisitIntegerLiteral(const IntegerLiteral *LE) {
if (DiscardResult)
  return true;

auto Val = LE->getValue();
QualType LitTy = LE->getType();
if (Optional<PrimType> T = classify(LitTy))
  return emitConst(*T, getIntWidth(LitTy), LE->getValue(), LE);
return this->bail(LE);
138}

140template <class Emitter>
141bool ByteCodeExprGen<Emitter>::VisitParenExpr(const ParenExpr *PE) {
return this->Visit(PE->getSubExpr());
143}

145template <class Emitter>
146bool ByteCodeExprGen<Emitter>::VisitBinaryOperator(const BinaryOperator *BO) {
const Expr *LHS = BO->getLHS();
const Expr *RHS = BO->getRHS();

// Deal with operations which have composite or void types.
switch (BO->getOpcode()) {
case BO_Comma:
  if (!discard(LHS))
    return false;
  if (!this->Visit(RHS))
    return false;
  return true;
default:
  break;
}

// Typecheck the args.
Optional<PrimType> LT = classify(LHS->getType());
Optional<PrimType> RT = classify(RHS->getType());
if (!LT || !RT) {
  return this->bail(BO);
}

if (Optional<PrimType> T = classify(BO->getType())) {
  if (!visit(LHS))
    return false;
  if (!visit(RHS))
    return false;

  auto Discard = [this, T, BO](bool Result) {
    if (!Result)
      return false;
    return DiscardResult ? this->emitPop(*T, BO) : true;
  };

  switch (BO->getOpcode()) {
  case BO_EQ:
    return Discard(this->emitEQ(*LT, BO));
  case BO_NE:
    return Discard(this->emitNE(*LT, BO));
  case BO_LT:
    return Discard(this->emitLT(*LT, BO));
  case BO_LE:
    return Discard(this->emitLE(*LT, BO));
  case BO_GT:
    return Discard(this->emitGT(*LT, BO));
  case BO_GE:
    return Discard(this->emitGE(*LT, BO));
  case BO_Sub:
    return Discard(this->emitSub(*T, BO));
  case BO_Add:
    return Discard(this->emitAdd(*T, BO));
  case BO_Mul:
    return Discard(this->emitMul(*T, BO));
  default:
    return this->bail(BO);
  }
}

return this->bail(BO);
206}

208template <class Emitter>
209bool ByteCodeExprGen<Emitter>::discard(const Expr *E) {
OptionScope<Emitter> Scope(this, /*discardResult=*/true);
return this->Visit(E);
212}

214template <class Emitter>
215bool ByteCodeExprGen<Emitter>::visit(const Expr *E) {
OptionScope<Emitter> Scope(this, /*discardResult=*/false);
return this->Visit(E);
218}

220template <class Emitter>
221bool ByteCodeExprGen<Emitter>::visitBool(const Expr *E) {
if (Optional<PrimType> T = classify(E->getType())) {
  return visit(E);
} else {
  return this->bail(E);
}
227}

229template <class Emitter>
230bool ByteCodeExprGen<Emitter>::visitZeroInitializer(PrimType T, const Expr *E) {
switch (T) {
case PT_Bool:
  return this->emitZeroBool(E);
case PT_Sint8:
  return this->emitZeroSint8(E);
case PT_Uint8:
  return this->emitZeroUint8(E);
case PT_Sint16:
  return this->emitZeroSint16(E);
case PT_Uint16:
  return this->emitZeroUint16(E);
case PT_Sint32:
  return this->emitZeroSint32(E);
case PT_Uint32:
  return this->emitZeroUint32(E);
case PT_Sint64:
  return this->emitZeroSint64(E);
case PT_Uint64:
  return this->emitZeroUint64(E);
case PT_Ptr:
  return this->emitNullPtr(E);
}
llvm_unreachable("unknown primitive type")__builtin_unreachable();
254}

256template <class Emitter>
257bool ByteCodeExprGen<Emitter>::dereference(
  const Expr *LV, DerefKind AK, llvm::function_ref<bool(PrimType)> Direct,
  llvm::function_ref<bool(PrimType)> Indirect) {
if (Optional<PrimType> T = classify(LV->getType())) {
  if (!LV->refersToBitField()) {
    // Only primitive, non bit-field types can be dereferenced directly.
    if (auto *DE = dyn_cast<DeclRefExpr>(LV)) {
      if (!DE->getDecl()->getType()->isReferenceType()) {
        if (auto *PD = dyn_cast<ParmVarDecl>(DE->getDecl()))
          return dereferenceParam(LV, *T, PD, AK, Direct, Indirect);
        if (auto *VD = dyn_cast<VarDecl>(DE->getDecl()))
          return dereferenceVar(LV, *T, VD, AK, Direct, Indirect);
      }
    }
  }

  if (!visit(LV))
    return false;
  return Indirect(*T);
}

return false;
279}

281template <class Emitter>
282bool ByteCodeExprGen<Emitter>::dereferenceParam(
  const Expr *LV, PrimType T, const ParmVarDecl *PD, DerefKind AK,
  llvm::function_ref<bool(PrimType)> Direct,
  llvm::function_ref<bool(PrimType)> Indirect) {
auto It = this->Params.find(PD);
if (It != this->Params.end()) {
  unsigned Idx = It->second;
  switch (AK) {
  case DerefKind::Read:
    return DiscardResult ? true : this->emitGetParam(T, Idx, LV);

  case DerefKind::Write:
    if (!Direct(T))
      return false;
    if (!this->emitSetParam(T, Idx, LV))
      return false;
    return DiscardResult ? true : this->emitGetPtrParam(Idx, LV);

  case DerefKind::ReadWrite:
    if (!this->emitGetParam(T, Idx, LV))
      return false;
    if (!Direct(T))
      return false;
    if (!this->emitSetParam(T, Idx, LV))
      return false;
    return DiscardResult ? true : this->emitGetPtrParam(Idx, LV);
  }
  return true;
}

// If the param is a pointer, we can dereference a dummy value.
if (!DiscardResult && T == PT_Ptr && AK == DerefKind::Read) {
  if (auto Idx = P.getOrCreateDummy(PD))
    return this->emitGetPtrGlobal(*Idx, PD);
  return false;
}

// Value cannot be produced - try to emit pointer and do stuff with it.
return visit(LV) && Indirect(T);
321}

323template <class Emitter>
324bool ByteCodeExprGen<Emitter>::dereferenceVar(
  const Expr *LV, PrimType T, const VarDecl *VD, DerefKind AK,
  llvm::function_ref<bool(PrimType)> Direct,
  llvm::function_ref<bool(PrimType)> Indirect) {
auto It = Locals.find(VD);
if (It != Locals.end()) {
  const auto &L = It->second;
  switch (AK) {
  case DerefKind::Read:
    if (!this->emitGetLocal(T, L.Offset, LV))
      return false;
    return DiscardResult ? this->emitPop(T, LV) : true;

  case DerefKind::Write:
    if (!Direct(T))
      return false;
    if (!this->emitSetLocal(T, L.Offset, LV))
      return false;
    return DiscardResult ? true : this->emitGetPtrLocal(L.Offset, LV);

  case DerefKind::ReadWrite:
    if (!this->emitGetLocal(T, L.Offset, LV))
      return false;
    if (!Direct(T))
      return false;
    if (!this->emitSetLocal(T, L.Offset, LV))
      return false;
    return DiscardResult ? true : this->emitGetPtrLocal(L.Offset, LV);
  }
} else if (auto Idx = getGlobalIdx(VD)) {
  switch (AK) {
  case DerefKind::Read:
    if (!this->emitGetGlobal(T, *Idx, LV))
      return false;
    return DiscardResult ? this->emitPop(T, LV) : true;

  case DerefKind::Write:
    if (!Direct(T))
      return false;
    if (!this->emitSetGlobal(T, *Idx, LV))
      return false;
    return DiscardResult ? true : this->emitGetPtrGlobal(*Idx, LV);

  case DerefKind::ReadWrite:
    if (!this->emitGetGlobal(T, *Idx, LV))
      return false;
    if (!Direct(T))
      return false;
    if (!this->emitSetGlobal(T, *Idx, LV))
      return false;
    return DiscardResult ? true : this->emitGetPtrGlobal(*Idx, LV);
  }
}

// If the declaration is a constant value, emit it here even
// though the declaration was not evaluated in the current scope.
// The access mode can only be read in this case.
if (!DiscardResult && AK == DerefKind::Read) {
  if (VD->hasLocalStorage() && VD->hasInit() && !VD->isConstexpr()) {
    QualType VT = VD->getType();
    if (VT.isConstQualified() && VT->isFundamentalType())
      return this->Visit(VD->getInit());
  }
}

// Value cannot be produced - try to emit pointer.
return visit(LV) && Indirect(T);
391}

393template <class Emitter>
394bool ByteCodeExprGen<Emitter>::emitConst(PrimType T, unsigned NumBits,
                                       const APInt &Value, const Expr *E) {
switch (T) {
case PT_Sint8:
  return this->emitConstSint8(Value.getSExtValue(), E);
case PT_Uint8:
  return this->emitConstUint8(Value.getZExtValue(), E);
case PT_Sint16:
  return this->emitConstSint16(Value.getSExtValue(), E);
case PT_Uint16:
  return this->emitConstUint16(Value.getZExtValue(), E);
case PT_Sint32:
  return this->emitConstSint32(Value.getSExtValue(), E);
case PT_Uint32:
  return this->emitConstUint32(Value.getZExtValue(), E);
case PT_Sint64:
  return this->emitConstSint64(Value.getSExtValue(), E);
case PT_Uint64:
  return this->emitConstUint64(Value.getZExtValue(), E);
case PT_Bool:
  return this->emitConstBool(Value.getBoolValue(), E);
case PT_Ptr:
  llvm_unreachable("Invalid integral type")__builtin_unreachable();
  break;
}
llvm_unreachable("unknown primitive type")__builtin_unreachable();
420}

422template <class Emitter>
423unsigned ByteCodeExprGen<Emitter>::allocateLocalPrimitive(DeclTy &&Src,
                                                        PrimType Ty,
                                                        bool IsConst,
                                                        bool IsExtended) {
Descriptor *D = P.createDescriptor(Src, Ty, IsConst, Src.is<const Expr *>());
1
Calling 'Program::createDescriptor'→
Scope::Local Local = this->createLocal(D);
if (auto *VD = dyn_cast_or_null<ValueDecl>(Src.dyn_cast<const Decl *>()))
  Locals.insert({VD, Local});
VarScope->add(Local, IsExtended);
return Local.Offset;
433}

435template <class Emitter>
436llvm::Optional<unsigned>
437ByteCodeExprGen<Emitter>::allocateLocal(DeclTy &&Src, bool IsExtended) {
QualType Ty;

const ValueDecl *Key = nullptr;
bool IsTemporary = false;
if (auto *VD = dyn_cast_or_null<ValueDecl>(Src.dyn_cast<const Decl *>())) {
  Key = VD;
  Ty = VD->getType();
}
if (auto *E = Src.dyn_cast<const Expr *>()) {
  IsTemporary = true;
  Ty = E->getType();
}

Descriptor *D = P.createDescriptor(Src, Ty.getTypePtr(),
                                   Ty.isConstQualified(), IsTemporary);
if (!D)
  return {};

Scope::Local Local = this->createLocal(D);
if (Key)
  Locals.insert({Key, Local});
VarScope->add(Local, IsExtended);
return Local.Offset;
461}

463template <class Emitter>
464bool ByteCodeExprGen<Emitter>::visitInitializer(
  const Expr *Init, InitFnRef InitFn) {
OptionScope<Emitter> Scope(this, InitFn);
return this->Visit(Init);
468}

470template <class Emitter>
471bool ByteCodeExprGen<Emitter>::getPtrVarDecl(const VarDecl *VD, const Expr *E) {
// Generate a pointer to the local, loading refs.
if (Optional<unsigned> Idx = getGlobalIdx(VD)) {
  if (VD->getType()->isReferenceType())
    return this->emitGetGlobalPtr(*Idx, E);
  else
    return this->emitGetPtrGlobal(*Idx, E);
}
return this->bail(VD);
480}

482template <class Emitter>
483llvm::Optional<unsigned>
484ByteCodeExprGen<Emitter>::getGlobalIdx(const VarDecl *VD) {
if (VD->isConstexpr()) {
  // Constexpr decl - it must have already been defined.
  return P.getGlobal(VD);
}
if (!VD->hasLocalStorage()) {
  // Not constexpr, but a global var - can have pointer taken.
  Program::DeclScope Scope(P, VD);
  return P.getOrCreateGlobal(VD);
}
return {};
495}

497template <class Emitter>
498const RecordType *ByteCodeExprGen<Emitter>::getRecordTy(QualType Ty) {
if (auto *PT = dyn_cast<PointerType>(Ty))
  return PT->getPointeeType()->getAs<RecordType>();
else
  return Ty->getAs<RecordType>();
503}

505template <class Emitter>
506Record *ByteCodeExprGen<Emitter>::getRecord(QualType Ty) {
if (auto *RecordTy = getRecordTy(Ty)) {
  return getRecord(RecordTy->getDecl());
}
return nullptr;
511}

513template <class Emitter>
514Record *ByteCodeExprGen<Emitter>::getRecord(const RecordDecl *RD) {
return P.getOrCreateRecord(RD);
516}

518template <class Emitter>
519bool ByteCodeExprGen<Emitter>::visitExpr(const Expr *Exp) {
ExprScope<Emitter> RootScope(this);
if (!visit(Exp))
  return false;

if (Optional<PrimType> T = classify(Exp))
  return this->emitRet(*T, Exp);
else
  return this->emitRetValue(Exp);
528}

530template <class Emitter>
531bool ByteCodeExprGen<Emitter>::visitDecl(const VarDecl *VD) {
const Expr *Init = VD->getInit();

if (Optional<unsigned> I = P.createGlobal(VD)) {
  if (Optional<PrimType> T = classify(VD->getType())) {
    {
      // Primitive declarations - compute the value and set it.
      DeclScope<Emitter> LocalScope(this, VD);
      if (!visit(Init))
        return false;
    }

    // If the declaration is global, save the value for later use.
    if (!this->emitDup(*T, VD))
      return false;
    if (!this->emitInitGlobal(*T, *I, VD))
      return false;
    return this->emitRet(*T, VD);
  } else {
    {
      // Composite declarations - allocate storage and initialize it.
      DeclScope<Emitter> LocalScope(this, VD);
      if (!visitGlobalInitializer(Init, *I))
        return false;
    }

    // Return a pointer to the global.
    if (!this->emitGetPtrGlobal(*I, VD))
      return false;
    return this->emitRetValue(VD);
  }
}

return this->bail(VD);
565}

567template <class Emitter>
568void ByteCodeExprGen<Emitter>::emitCleanup() {
for (VariableScope<Emitter> *C = VarScope; C; C = C->getParent())
  C->emitDestruction();
571}

573namespace clang {
574namespace interp {

576template class ByteCodeExprGen<ByteCodeEmitter>;
577template class ByteCodeExprGen<EvalEmitter>;

579} // namespace interp
580} // namespace clang

←

/usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/clang/lib/AST/Interp/Program.h

→

1//===--- Program.h - Bytecode for the constexpr VM --------------*- C++ -*-===//
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// Defines a program which organises and links multiple bytecode functions.
10//
11//===----------------------------------------------------------------------===//

13#ifndef LLVM_CLANG_AST_INTERP_PROGRAM_H
14#define LLVM_CLANG_AST_INTERP_PROGRAM_H

16#include <map>
17#include <vector>
18#include "Function.h"
19#include "Pointer.h"
20#include "PrimType.h"
21#include "Record.h"
22#include "Source.h"
23#include "llvm/ADT/DenseMap.h"
24#include "llvm/ADT/PointerUnion.h"
25#include "llvm/ADT/StringRef.h"
26#include "llvm/Support/Allocator.h"

28namespace clang {
29class RecordDecl;
30class Expr;
31class FunctionDecl;
32class Stmt;
33class StringLiteral;
34class VarDecl;

36namespace interp {
37class Context;
38class State;
39class Record;
40class Scope;

42/// The program contains and links the bytecode for all functions.
43class Program {
44public:
Program(Context &Ctx) : Ctx(Ctx) {}

/// Emits a string literal among global data.
unsigned createGlobalString(const StringLiteral *S);

/// Returns a pointer to a global.
Pointer getPtrGlobal(unsigned Idx);

/// Returns the value of a global.
Block *getGlobal(unsigned Idx) {
  assert(Idx < Globals.size())((void)0);
  return Globals[Idx]->block();
}

/// Finds a global's index.
llvm::Optional<unsigned> getGlobal(const ValueDecl *VD);

/// Returns or creates a global an creates an index to it.
llvm::Optional<unsigned> getOrCreateGlobal(const ValueDecl *VD);

/// Returns or creates a dummy value for parameters.
llvm::Optional<unsigned> getOrCreateDummy(const ParmVarDecl *PD);

/// Creates a global and returns its index.
llvm::Optional<unsigned> createGlobal(const ValueDecl *VD);

/// Creates a global from a lifetime-extended temporary.
llvm::Optional<unsigned> createGlobal(const Expr *E);

/// Creates a new function from a code range.
template <typename... Ts>
Function *createFunction(const FunctionDecl *Def, Ts &&... Args) {
  auto *Func = new Function(*this, Def, std::forward<Ts>(Args)...);
  Funcs.insert({Def, std::unique_ptr<Function>(Func)});
  return Func;
}
/// Creates an anonymous function.
template <typename... Ts>
Function *createFunction(Ts &&... Args) {
  auto *Func = new Function(*this, std::forward<Ts>(Args)...);
  AnonFuncs.emplace_back(Func);
  return Func;
}

/// Returns a function.
Function *getFunction(const FunctionDecl *F);

/// Returns a pointer to a function if it exists and can be compiled.
/// If a function couldn't be compiled, an error is returned.
/// If a function was not yet defined, a null pointer is returned.
llvm::Expected<Function *> getOrCreateFunction(const FunctionDecl *F);

/// Returns a record or creates one if it does not exist.
Record *getOrCreateRecord(const RecordDecl *RD);

/// Creates a descriptor for a primitive type.
Descriptor *createDescriptor(const DeclTy &D, PrimType Type,
                             bool IsConst = false,
                             bool IsTemporary = false,
                             bool IsMutable = false) {
  return allocateDescriptor(D, Type, IsConst, IsTemporary, IsMutable);
2
←
Calling 'Program::allocateDescriptor'→
}

/// Creates a descriptor for a composite type.
Descriptor *createDescriptor(const DeclTy &D, const Type *Ty,
                             bool IsConst = false, bool IsTemporary = false,
                             bool IsMutable = false);

/// Context to manage declaration lifetimes.
class DeclScope {
public:
  DeclScope(Program &P, const VarDecl *VD) : P(P) { P.startDeclaration(VD); }
  ~DeclScope() { P.endDeclaration(); }

private:
  Program &P;
};

/// Returns the current declaration ID.
llvm::Optional<unsigned> getCurrentDecl() const {
  if (CurrentDeclaration == NoDeclaration)
    return llvm::Optional<unsigned>{};
  return LastDeclaration;
}

130private:
friend class DeclScope;

llvm::Optional<unsigned> createGlobal(const DeclTy &D, QualType Ty,
                                      bool IsStatic, bool IsExtern);

/// Reference to the VM context.
Context &Ctx;
/// Mapping from decls to cached bytecode functions.
llvm::DenseMap<const FunctionDecl *, std::unique_ptr<Function>> Funcs;
/// List of anonymous functions.
std::vector<std::unique_ptr<Function>> AnonFuncs;

/// Function relocation locations.
llvm::DenseMap<const FunctionDecl *, std::vector<unsigned>> Relocs;

/// Custom allocator for global storage.
using PoolAllocTy = llvm::BumpPtrAllocatorImpl<llvm::MallocAllocator>;

/// Descriptor + storage for a global object.
///
/// Global objects never go out of scope, thus they do not track pointers.
class Global {
public:
  /// Create a global descriptor for string literals.
  template <typename... Tys>
  Global(Tys... Args) : B(std::forward<Tys>(Args)...) {}

  /// Allocates the global in the pool, reserving storate for data.
  void *operator new(size_t Meta, PoolAllocTy &Alloc, size_t Data) {
    return Alloc.Allocate(Meta + Data, alignof(void *));
  }

  /// Return a pointer to the data.
  char *data() { return B.data(); }
  /// Return a pointer to the block.
  Block *block() { return &B; }

private:
  /// Required metadata - does not actually track pointers.
  Block B;
};

/// Allocator for globals.
PoolAllocTy Allocator;

/// Global objects.
std::vector<Global *> Globals;
/// Cached global indices.
llvm::DenseMap<const void *, unsigned> GlobalIndices;

/// Mapping from decls to record metadata.
llvm::DenseMap<const RecordDecl *, Record *> Records;

/// Dummy parameter to generate pointers from.
llvm::DenseMap<const ParmVarDecl *, unsigned> DummyParams;

/// Creates a new descriptor.
template <typename... Ts>
Descriptor *allocateDescriptor(Ts &&... Args) {
  return new (Allocator) Descriptor(std::forward<Ts>(Args)...);
3
←
Calling 'operator new<llvm::MallocAllocator, 4096UL, 4096UL, 128UL>'→
}

/// No declaration ID.
static constexpr unsigned NoDeclaration = (unsigned)-1;
/// Last declaration ID.
unsigned LastDeclaration = 0;
/// Current declaration ID.
unsigned CurrentDeclaration = NoDeclaration;

/// Starts evaluating a declaration.
void startDeclaration(const VarDecl *Decl) {
  LastDeclaration += 1;
  CurrentDeclaration = LastDeclaration;
}

/// Ends a global declaration.
void endDeclaration() {
  CurrentDeclaration = NoDeclaration;
}

211public:
/// Dumps the disassembled bytecode to \c llvm::errs().
void dump() const;
void dump(llvm::raw_ostream &OS) const;
215};

217} // namespace interp
218} // namespace clang

220#endif

←

/usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/llvm/include/llvm/Support/Allocator.h

→

1//===- Allocator.h - Simple memory allocation abstraction -------*- C++ -*-===//
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/// \file
9///
10/// This file defines the BumpPtrAllocator interface. BumpPtrAllocator conforms
11/// to the LLVM "Allocator" concept and is similar to MallocAllocator, but
12/// objects cannot be deallocated. Their lifetime is tied to the lifetime of the
13/// allocator.
14///
15//===----------------------------------------------------------------------===//

17#ifndef LLVM_SUPPORT_ALLOCATOR_H
18#define LLVM_SUPPORT_ALLOCATOR_H

20#include "llvm/ADT/Optional.h"
21#include "llvm/ADT/SmallVector.h"
22#include "llvm/Support/Alignment.h"
23#include "llvm/Support/AllocatorBase.h"
24#include "llvm/Support/Compiler.h"
25#include "llvm/Support/ErrorHandling.h"
26#include "llvm/Support/MathExtras.h"
27#include "llvm/Support/MemAlloc.h"
28#include <algorithm>
29#include <cassert>
30#include <cstddef>
31#include <cstdint>
32#include <cstdlib>
33#include <iterator>
34#include <type_traits>
35#include <utility>

37namespace llvm {

39namespace detail {

41// We call out to an external function to actually print the message as the
42// printing code uses Allocator.h in its implementation.
43void printBumpPtrAllocatorStats(unsigned NumSlabs, size_t BytesAllocated,
                              size_t TotalMemory);

46} // end namespace detail

48/// Allocate memory in an ever growing pool, as if by bump-pointer.
49///
50/// This isn't strictly a bump-pointer allocator as it uses backing slabs of
51/// memory rather than relying on a boundless contiguous heap. However, it has
52/// bump-pointer semantics in that it is a monotonically growing pool of memory
53/// where every allocation is found by merely allocating the next N bytes in
54/// the slab, or the next N bytes in the next slab.
55///
56/// Note that this also has a threshold for forcing allocations above a certain
57/// size into their own slab.
58///
59/// The BumpPtrAllocatorImpl template defaults to using a MallocAllocator
60/// object, which wraps malloc, to allocate memory, but it can be changed to
61/// use a custom allocator.
62///
63/// The GrowthDelay specifies after how many allocated slabs the allocator
64/// increases the size of the slabs.
65template <typename AllocatorT = MallocAllocator, size_t SlabSize = 4096,
        size_t SizeThreshold = SlabSize, size_t GrowthDelay = 128>
67class BumpPtrAllocatorImpl
  : public AllocatorBase<BumpPtrAllocatorImpl<AllocatorT, SlabSize,
                                              SizeThreshold, GrowthDelay>>,
    private AllocatorT {
71public:
static_assert(SizeThreshold <= SlabSize,
              "The SizeThreshold must be at most the SlabSize to ensure "
              "that objects larger than a slab go into their own memory "
              "allocation.");
static_assert(GrowthDelay > 0,
              "GrowthDelay must be at least 1 which already increases the"
              "slab size after each allocated slab.");

BumpPtrAllocatorImpl() = default;

template <typename T>
BumpPtrAllocatorImpl(T &&Allocator)
    : AllocatorT(std::forward<T &&>(Allocator)) {}

// Manually implement a move constructor as we must clear the old allocator's
// slabs as a matter of correctness.
BumpPtrAllocatorImpl(BumpPtrAllocatorImpl &&Old)
    : AllocatorT(static_cast<AllocatorT &&>(Old)), CurPtr(Old.CurPtr),
      End(Old.End), Slabs(std::move(Old.Slabs)),
      CustomSizedSlabs(std::move(Old.CustomSizedSlabs)),
      BytesAllocated(Old.BytesAllocated), RedZoneSize(Old.RedZoneSize) {
  Old.CurPtr = Old.End = nullptr;
  Old.BytesAllocated = 0;
  Old.Slabs.clear();
  Old.CustomSizedSlabs.clear();
}

~BumpPtrAllocatorImpl() {
  DeallocateSlabs(Slabs.begin(), Slabs.end());
  DeallocateCustomSizedSlabs();
}

BumpPtrAllocatorImpl &operator=(BumpPtrAllocatorImpl &&RHS) {
  DeallocateSlabs(Slabs.begin(), Slabs.end());
  DeallocateCustomSizedSlabs();

  CurPtr = RHS.CurPtr;
  End = RHS.End;
  BytesAllocated = RHS.BytesAllocated;
  RedZoneSize = RHS.RedZoneSize;
  Slabs = std::move(RHS.Slabs);
  CustomSizedSlabs = std::move(RHS.CustomSizedSlabs);
  AllocatorT::operator=(static_cast<AllocatorT &&>(RHS));

  RHS.CurPtr = RHS.End = nullptr;
  RHS.BytesAllocated = 0;
  RHS.Slabs.clear();
  RHS.CustomSizedSlabs.clear();
  return *this;
}

/// Deallocate all but the current slab and reset the current pointer
/// to the beginning of it, freeing all memory allocated so far.
void Reset() {
  // Deallocate all but the first slab, and deallocate all custom-sized slabs.
  DeallocateCustomSizedSlabs();
  CustomSizedSlabs.clear();

  if (Slabs.empty())
    return;

  // Reset the state.
  BytesAllocated = 0;
  CurPtr = (char *)Slabs.front();
  End = CurPtr + SlabSize;

  __asan_poison_memory_region(*Slabs.begin(), computeSlabSize(0));
  DeallocateSlabs(std::next(Slabs.begin()), Slabs.end());
  Slabs.erase(std::next(Slabs.begin()), Slabs.end());
}

/// Allocate space at the specified alignment.
LLVM_ATTRIBUTE_RETURNS_NONNULL__attribute__((returns_nonnull)) LLVM_ATTRIBUTE_RETURNS_NOALIAS__attribute__((__malloc__)) void *
Allocate(size_t Size, Align Alignment) {
  // Keep track of how many bytes we've allocated.
  BytesAllocated += Size;

  size_t Adjustment = offsetToAlignedAddr(CurPtr, Alignment);
6
←
Calling 'offsetToAlignedAddr'→
  assert(Adjustment + Size >= Size && "Adjustment + Size must not overflow")((void)0);

  size_t SizeToAllocate = Size;
153#if LLVM_ADDRESS_SANITIZER_BUILD0
  // Add trailing bytes as a "red zone" under ASan.
  SizeToAllocate += RedZoneSize;
156#endif

  // Check if we have enough space.
  if (Adjustment + SizeToAllocate <= size_t(End - CurPtr)) {
    char *AlignedPtr = CurPtr + Adjustment;
    CurPtr = AlignedPtr + SizeToAllocate;
    // Update the allocation point of this memory block in MemorySanitizer.
    // Without this, MemorySanitizer messages for values originated from here
    // will point to the allocation of the entire slab.
    __msan_allocated_memory(AlignedPtr, Size);
    // Similarly, tell ASan about this space.
    __asan_unpoison_memory_region(AlignedPtr, Size);
    return AlignedPtr;
  }

  // If Size is really big, allocate a separate slab for it.
  size_t PaddedSize = SizeToAllocate + Alignment.value() - 1;
  if (PaddedSize > SizeThreshold) {
    void *NewSlab =
        AllocatorT::Allocate(PaddedSize, alignof(std::max_align_t));
    // We own the new slab and don't want anyone reading anyting other than
    // pieces returned from this method.  So poison the whole slab.
    __asan_poison_memory_region(NewSlab, PaddedSize);
    CustomSizedSlabs.push_back(std::make_pair(NewSlab, PaddedSize));

    uintptr_t AlignedAddr = alignAddr(NewSlab, Alignment);
    assert(AlignedAddr + Size <= (uintptr_t)NewSlab + PaddedSize)((void)0);
    char *AlignedPtr = (char*)AlignedAddr;
    __msan_allocated_memory(AlignedPtr, Size);
    __asan_unpoison_memory_region(AlignedPtr, Size);
    return AlignedPtr;
  }

  // Otherwise, start a new slab and try again.
  StartNewSlab();
  uintptr_t AlignedAddr = alignAddr(CurPtr, Alignment);
  assert(AlignedAddr + SizeToAllocate <= (uintptr_t)End &&((void)0)
         "Unable to allocate memory!")((void)0);
  char *AlignedPtr = (char*)AlignedAddr;
  CurPtr = AlignedPtr + SizeToAllocate;
  __msan_allocated_memory(AlignedPtr, Size);
  __asan_unpoison_memory_region(AlignedPtr, Size);
  return AlignedPtr;
}

inline LLVM_ATTRIBUTE_RETURNS_NONNULL__attribute__((returns_nonnull)) LLVM_ATTRIBUTE_RETURNS_NOALIAS__attribute__((__malloc__)) void *
Allocate(size_t Size, size_t Alignment) {
  assert(Alignment > 0 && "0-byte alignment is not allowed. Use 1 instead.")((void)0);
  return Allocate(Size, Align(Alignment));
5
←
Calling 'BumpPtrAllocatorImpl::Allocate'→
}

// Pull in base class overloads.
using AllocatorBase<BumpPtrAllocatorImpl>::Allocate;

// Bump pointer allocators are expected to never free their storage; and
// clients expect pointers to remain valid for non-dereferencing uses even
// after deallocation.
void Deallocate(const void *Ptr, size_t Size, size_t /*Alignment*/) {
  __asan_poison_memory_region(Ptr, Size);
}

// Pull in base class overloads.
using AllocatorBase<BumpPtrAllocatorImpl>::Deallocate;

size_t GetNumSlabs() const { return Slabs.size() + CustomSizedSlabs.size(); }

/// \return An index uniquely and reproducibly identifying
/// an input pointer \p Ptr in the given allocator.
/// The returned value is negative iff the object is inside a custom-size
/// slab.
/// Returns an empty optional if the pointer is not found in the allocator.
llvm::Optional<int64_t> identifyObject(const void *Ptr) {
  const char *P = static_cast<const char *>(Ptr);
  int64_t InSlabIdx = 0;
  for (size_t Idx = 0, E = Slabs.size(); Idx < E; Idx++) {
    const char *S = static_cast<const char *>(Slabs[Idx]);
    if (P >= S && P < S + computeSlabSize(Idx))
      return InSlabIdx + static_cast<int64_t>(P - S);
    InSlabIdx += static_cast<int64_t>(computeSlabSize(Idx));
  }

  // Use negative index to denote custom sized slabs.
  int64_t InCustomSizedSlabIdx = -1;
  for (size_t Idx = 0, E = CustomSizedSlabs.size(); Idx < E; Idx++) {
    const char *S = static_cast<const char *>(CustomSizedSlabs[Idx].first);
    size_t Size = CustomSizedSlabs[Idx].second;
    if (P >= S && P < S + Size)
      return InCustomSizedSlabIdx - static_cast<int64_t>(P - S);
    InCustomSizedSlabIdx -= static_cast<int64_t>(Size);
  }
  return None;
}

/// A wrapper around identifyObject that additionally asserts that
/// the object is indeed within the allocator.
/// \return An index uniquely and reproducibly identifying
/// an input pointer \p Ptr in the given allocator.
int64_t identifyKnownObject(const void *Ptr) {
  Optional<int64_t> Out = identifyObject(Ptr);
  assert(Out && "Wrong allocator used")((void)0);
  return *Out;
}

/// A wrapper around identifyKnownObject. Accepts type information
/// about the object and produces a smaller identifier by relying on
/// the alignment information. Note that sub-classes may have different
/// alignment, so the most base class should be passed as template parameter
/// in order to obtain correct results. For that reason automatic template
/// parameter deduction is disabled.
/// \return An index uniquely and reproducibly identifying
/// an input pointer \p Ptr in the given allocator. This identifier is
/// different from the ones produced by identifyObject and
/// identifyAlignedObject.
template <typename T>
int64_t identifyKnownAlignedObject(const void *Ptr) {
  int64_t Out = identifyKnownObject(Ptr);
  assert(Out % alignof(T) == 0 && "Wrong alignment information")((void)0);
  return Out / alignof(T);
}

size_t getTotalMemory() const {
  size_t TotalMemory = 0;
  for (auto I = Slabs.begin(), E = Slabs.end(); I != E; ++I)
    TotalMemory += computeSlabSize(std::distance(Slabs.begin(), I));
  for (auto &PtrAndSize : CustomSizedSlabs)
    TotalMemory += PtrAndSize.second;
  return TotalMemory;
}

size_t getBytesAllocated() const { return BytesAllocated; }

void setRedZoneSize(size_t NewSize) {
  RedZoneSize = NewSize;
}

void PrintStats() const {
  detail::printBumpPtrAllocatorStats(Slabs.size(), BytesAllocated,
                                     getTotalMemory());
}

296private:
/// The current pointer into the current slab.
///
/// This points to the next free byte in the slab.
char *CurPtr = nullptr;

/// The end of the current slab.
char *End = nullptr;

/// The slabs allocated so far.
SmallVector<void *, 4> Slabs;

/// Custom-sized slabs allocated for too-large allocation requests.
SmallVector<std::pair<void *, size_t>, 0> CustomSizedSlabs;

/// How many bytes we've allocated.
///
/// Used so that we can compute how much space was wasted.
size_t BytesAllocated = 0;

/// The number of bytes to put between allocations when running under
/// a sanitizer.
size_t RedZoneSize = 1;

static size_t computeSlabSize(unsigned SlabIdx) {
  // Scale the actual allocated slab size based on the number of slabs
  // allocated. Every GrowthDelay slabs allocated, we double
  // the allocated size to reduce allocation frequency, but saturate at
  // multiplying the slab size by 2^30.
  return SlabSize *
         ((size_t)1 << std::min<size_t>(30, SlabIdx / GrowthDelay));
}

/// Allocate a new slab and move the bump pointers over into the new
/// slab, modifying CurPtr and End.
void StartNewSlab() {
  size_t AllocatedSlabSize = computeSlabSize(Slabs.size());

  void *NewSlab =
      AllocatorT::Allocate(AllocatedSlabSize, alignof(std::max_align_t));
  // We own the new slab and don't want anyone reading anything other than
  // pieces returned from this method.  So poison the whole slab.
  __asan_poison_memory_region(NewSlab, AllocatedSlabSize);

  Slabs.push_back(NewSlab);
  CurPtr = (char *)(NewSlab);
  End = ((char *)NewSlab) + AllocatedSlabSize;
}

/// Deallocate a sequence of slabs.
void DeallocateSlabs(SmallVectorImpl<void *>::iterator I,
                     SmallVectorImpl<void *>::iterator E) {
  for (; I != E; ++I) {
    size_t AllocatedSlabSize =
        computeSlabSize(std::distance(Slabs.begin(), I));
    AllocatorT::Deallocate(*I, AllocatedSlabSize, alignof(std::max_align_t));
  }
}

/// Deallocate all memory for custom sized slabs.
void DeallocateCustomSizedSlabs() {
  for (auto &PtrAndSize : CustomSizedSlabs) {
    void *Ptr = PtrAndSize.first;
    size_t Size = PtrAndSize.second;
    AllocatorT::Deallocate(Ptr, Size, alignof(std::max_align_t));
  }
}

template <typename T> friend class SpecificBumpPtrAllocator;
365};

367/// The standard BumpPtrAllocator which just uses the default template
368/// parameters.
369typedef BumpPtrAllocatorImpl<> BumpPtrAllocator;

371/// A BumpPtrAllocator that allows only elements of a specific type to be
372/// allocated.
373///
374/// This allows calling the destructor in DestroyAll() and when the allocator is
375/// destroyed.
376template <typename T> class SpecificBumpPtrAllocator {
BumpPtrAllocator Allocator;

379public:
SpecificBumpPtrAllocator() {
  // Because SpecificBumpPtrAllocator walks the memory to call destructors,
  // it can't have red zones between allocations.
  Allocator.setRedZoneSize(0);
}
SpecificBumpPtrAllocator(SpecificBumpPtrAllocator &&Old)
    : Allocator(std::move(Old.Allocator)) {}
~SpecificBumpPtrAllocator() { DestroyAll(); }

SpecificBumpPtrAllocator &operator=(SpecificBumpPtrAllocator &&RHS) {
  Allocator = std::move(RHS.Allocator);
  return *this;
}

/// Call the destructor of each allocated object and deallocate all but the
/// current slab and reset the current pointer to the beginning of it, freeing
/// all memory allocated so far.
void DestroyAll() {
  auto DestroyElements = [](char *Begin, char *End) {
    assert(Begin == (char *)alignAddr(Begin, Align::Of<T>()))((void)0);
    for (char *Ptr = Begin; Ptr + sizeof(T) <= End; Ptr += sizeof(T))
      reinterpret_cast<T *>(Ptr)->~T();
  };

  for (auto I = Allocator.Slabs.begin(), E = Allocator.Slabs.end(); I != E;
       ++I) {
    size_t AllocatedSlabSize = BumpPtrAllocator::computeSlabSize(
        std::distance(Allocator.Slabs.begin(), I));
    char *Begin = (char *)alignAddr(*I, Align::Of<T>());
    char *End = *I == Allocator.Slabs.back() ? Allocator.CurPtr
                                             : (char *)*I + AllocatedSlabSize;

    DestroyElements(Begin, End);
  }

  for (auto &PtrAndSize : Allocator.CustomSizedSlabs) {
    void *Ptr = PtrAndSize.first;
    size_t Size = PtrAndSize.second;
    DestroyElements((char *)alignAddr(Ptr, Align::Of<T>()),
                    (char *)Ptr + Size);
  }

  Allocator.Reset();
}

/// Allocate space for an array of objects without constructing them.
T *Allocate(size_t num = 1) { return Allocator.Allocate<T>(num); }
427};

429} // end namespace llvm

431template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold,
        size_t GrowthDelay>
433void *
434operator new(size_t Size,
           llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold,
                                      GrowthDelay> &Allocator) {
return Allocator.Allocate(Size, std::min((size_t)llvm::NextPowerOf2(Size),
4
←
Calling 'BumpPtrAllocatorImpl::Allocate'→
                                         alignof(std::max_align_t)));
439}

441template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold,
        size_t GrowthDelay>
443void operator delete(void *,
                   llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize,
                                              SizeThreshold, GrowthDelay> &) {
446}

448#endif // LLVM_SUPPORT_ALLOCATOR_H

←

/usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/llvm/include/llvm/Support/Alignment.h

1//===-- llvm/Support/Alignment.h - Useful alignment functions ---*- C++ -*-===//
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 contains types to represent alignments.
10// They are instrumented to guarantee some invariants are preserved and prevent
11// invalid manipulations.
12//
13// - Align represents an alignment in bytes, it is always set and always a valid
14// power of two, its minimum value is 1 which means no alignment requirements.
15//
16// - MaybeAlign is an optional type, it may be undefined or set. When it's set
17// you can get the underlying Align type by using the getValue() method.
18//
19//===----------------------------------------------------------------------===//
20 
21#ifndef LLVM_SUPPORT_ALIGNMENT_H_
22#define LLVM_SUPPORT_ALIGNMENT_H_
23 
24#include "llvm/ADT/Optional.h"
25#include "llvm/Support/MathExtras.h"
26#include <cassert>
27#ifndef NDEBUG1
28#include <string>
29#endif // NDEBUG
30 
31namespace llvm {
32 
33#define ALIGN_CHECK_ISPOSITIVE(decl)                                           \
34  assert(decl > 0 && (#decl " should be defined"))((void)0)
35 
36/// This struct is a compact representation of a valid (non-zero power of two)
37/// alignment.
38/// It is suitable for use as static global constants.
39struct Align {
40private:
41  uint8_t ShiftValue = 0; /// The log2 of the required alignment.
42                          /// ShiftValue is less than 64 by construction.
43 
44  friend struct MaybeAlign;
45  friend unsigned Log2(Align);
46  friend bool operator==(Align Lhs, Align Rhs);
47  friend bool operator!=(Align Lhs, Align Rhs);
48  friend bool operator<=(Align Lhs, Align Rhs);
49  friend bool operator>=(Align Lhs, Align Rhs);
50  friend bool operator<(Align Lhs, Align Rhs);
51  friend bool operator>(Align Lhs, Align Rhs);
52  friend unsigned encode(struct MaybeAlign A);
53  friend struct MaybeAlign decodeMaybeAlign(unsigned Value);
54 
55  /// A trivial type to allow construction of constexpr Align.
56  /// This is currently needed to workaround a bug in GCC 5.3 which prevents
57  /// definition of constexpr assign operators.
58  /// https://stackoverflow.com/questions/46756288/explicitly-defaulted-function-cannot-be-declared-as-constexpr-because-the-implic
59  /// FIXME: Remove this, make all assign operators constexpr and introduce user
60  /// defined literals when we don't have to support GCC 5.3 anymore.
61  /// https://llvm.org/docs/GettingStarted.html#getting-a-modern-host-c-toolchain
62  struct LogValue {
63    uint8_t Log;
64  };
65 
66public:
67  /// Default is byte-aligned.
68  constexpr Align() = default;
69  /// Do not perform checks in case of copy/move construct/assign, because the
70  /// checks have been performed when building `Other`.
71  constexpr Align(const Align &Other) = default;
72  constexpr Align(Align &&Other) = default;
73  Align &operator=(const Align &Other) = default;
74  Align &operator=(Align &&Other) = default;
75 
76  explicit Align(uint64_t Value) {
77    assert(Value > 0 && "Value must not be 0")((void)0);
78    assert(llvm::isPowerOf2_64(Value) && "Alignment is not a power of 2")((void)0);
79    ShiftValue = Log2_64(Value);
80    assert(ShiftValue < 64 && "Broken invariant")((void)0);
81  }
82 
83  /// This is a hole in the type system and should not be abused.
84  /// Needed to interact with C for instance.
85  uint64_t value() const { return uint64_t(1) << ShiftValue; }
11
←
The result of the left shift is undefined due to shifting by '255', which is greater or equal to the width of type 'uint64_t'
86 
87  /// Allow constructions of constexpr Align.
88  template <size_t kValue> constexpr static LogValue Constant() {
89    return LogValue{static_cast<uint8_t>(CTLog2<kValue>())};
90  }
91 
92  /// Allow constructions of constexpr Align from types.
93  /// Compile time equivalent to Align(alignof(T)).
94  template <typename T> constexpr static LogValue Of() {
95    return Constant<std::alignment_of<T>::value>();
96  }
97 
98  /// Constexpr constructor from LogValue type.
99  constexpr Align(LogValue CA) : ShiftValue(CA.Log) {}
100};
101 
102/// Treats the value 0 as a 1, so Align is always at least 1.
103inline Align assumeAligned(uint64_t Value) {
104  return Value ? Align(Value) : Align();
105}
106 
107/// This struct is a compact representation of a valid (power of two) or
108/// undefined (0) alignment.
109struct MaybeAlign : public llvm::Optional<Align> {
110private:
111  using UP = llvm::Optional<Align>;
112 
113public:
114  /// Default is undefined.
115  MaybeAlign() = default;
116  /// Do not perform checks in case of copy/move construct/assign, because the
117  /// checks have been performed when building `Other`.
118  MaybeAlign(const MaybeAlign &Other) = default;
119  MaybeAlign &operator=(const MaybeAlign &Other) = default;
120  MaybeAlign(MaybeAlign &&Other) = default;
121  MaybeAlign &operator=(MaybeAlign &&Other) = default;
122 
123  /// Use llvm::Optional<Align> constructor.
124  using UP::UP;
125 
126  explicit MaybeAlign(uint64_t Value) {
127    assert((Value == 0 || llvm::isPowerOf2_64(Value)) &&((void)0)
128           "Alignment is neither 0 nor a power of 2")((void)0);
129    if (Value)
130      emplace(Value);
131  }
132 
133  /// For convenience, returns a valid alignment or 1 if undefined.
134  Align valueOrOne() const { return hasValue() ? getValue() : Align(); }
135};
136 
137/// Checks that SizeInBytes is a multiple of the alignment.
138inline bool isAligned(Align Lhs, uint64_t SizeInBytes) {
139  return SizeInBytes % Lhs.value() == 0;
140}
141 
142/// Checks that Addr is a multiple of the alignment.
143inline bool isAddrAligned(Align Lhs, const void *Addr) {
144  return isAligned(Lhs, reinterpret_cast<uintptr_t>(Addr));
145}
146 
147/// Returns a multiple of A needed to store `Size` bytes.
148inline uint64_t alignTo(uint64_t Size, Align A) {
149  const uint64_t Value = A.value();
10
←
Calling 'Align::value'→
150  // The following line is equivalent to `(Size + Value - 1) / Value * Value`.
151 
152  // The division followed by a multiplication can be thought of as a right
153  // shift followed by a left shift which zeros out the extra bits produced in
154  // the bump; `~(Value - 1)` is a mask where all those bits being zeroed out
155  // are just zero.
156 
157  // Most compilers can generate this code but the pattern may be missed when
158  // multiple functions gets inlined.
159  return (Size + Value - 1) & ~(Value - 1U);
160}
161 
162/// If non-zero \p Skew is specified, the return value will be a minimal integer
163/// that is greater than or equal to \p Size and equal to \p A * N + \p Skew for
164/// some integer N. If \p Skew is larger than \p A, its value is adjusted to '\p
165/// Skew mod \p A'.
166///
167/// Examples:
168/// \code
169///   alignTo(5, Align(8), 7) = 7
170///   alignTo(17, Align(8), 1) = 17
171///   alignTo(~0LL, Align(8), 3) = 3
172/// \endcode
173inline uint64_t alignTo(uint64_t Size, Align A, uint64_t Skew) {
174  const uint64_t Value = A.value();
175  Skew %= Value;
176  return ((Size + Value - 1 - Skew) & ~(Value - 1U)) + Skew;
177}
178 
179/// Returns a multiple of A needed to store `Size` bytes.
180/// Returns `Size` if current alignment is undefined.
181inline uint64_t alignTo(uint64_t Size, MaybeAlign A) {
182  return A ? alignTo(Size, A.getValue()) : Size;
183}
184 
185/// Aligns `Addr` to `Alignment` bytes, rounding up.
186inline uintptr_t alignAddr(const void *Addr, Align Alignment) {
187  uintptr_t ArithAddr = reinterpret_cast<uintptr_t>(Addr);
188  assert(static_cast<uintptr_t>(ArithAddr + Alignment.value() - 1) >=((void)0)
189             ArithAddr &&((void)0)
190         "Overflow")((void)0);
191  return alignTo(ArithAddr, Alignment);
192}
193 
194/// Returns the offset to the next integer (mod 2**64) that is greater than
195/// or equal to \p Value and is a multiple of \p Align.
196inline uint64_t offsetToAlignment(uint64_t Value, Align Alignment) {
197  return alignTo(Value, Alignment) - Value;
8
←
The value 255 is assigned to 'A.ShiftValue'→
9
←
Calling 'alignTo'→
198}
199 
200/// Returns the necessary adjustment for aligning `Addr` to `Alignment`
201/// bytes, rounding up.
202inline uint64_t offsetToAlignedAddr(const void *Addr, Align Alignment) {
203  return offsetToAlignment(reinterpret_cast<uintptr_t>(Addr), Alignment);
7
←
Calling 'offsetToAlignment'→
204}
205 
206/// Returns the log2 of the alignment.
207inline unsigned Log2(Align A) { return A.ShiftValue; }
208 
209/// Returns the alignment that satisfies both alignments.
210/// Same semantic as MinAlign.
211inline Align commonAlignment(Align A, Align B) { return std::min(A, B); }
212 
213/// Returns the alignment that satisfies both alignments.
214/// Same semantic as MinAlign.
215inline Align commonAlignment(Align A, uint64_t Offset) {
216  return Align(MinAlign(A.value(), Offset));
217}
218 
219/// Returns the alignment that satisfies both alignments.
220/// Same semantic as MinAlign.
221inline MaybeAlign commonAlignment(MaybeAlign A, MaybeAlign B) {
222  return A && B ? commonAlignment(*A, *B) : A ? A : B;
223}
224 
225/// Returns the alignment that satisfies both alignments.
226/// Same semantic as MinAlign.
227inline MaybeAlign commonAlignment(MaybeAlign A, uint64_t Offset) {
228  return MaybeAlign(MinAlign((*A).value(), Offset));
229}
230 
231/// Returns a representation of the alignment that encodes undefined as 0.
232inline unsigned encode(MaybeAlign A) { return A ? A->ShiftValue + 1 : 0; }
233 
234/// Dual operation of the encode function above.
235inline MaybeAlign decodeMaybeAlign(unsigned Value) {
236  if (Value == 0)
237    return MaybeAlign();
238  Align Out;
239  Out.ShiftValue = Value - 1;
240  return Out;
241}
242 
243/// Returns a representation of the alignment, the encoded value is positive by
244/// definition.
245inline unsigned encode(Align A) { return encode(MaybeAlign(A)); }
246 
247/// Comparisons between Align and scalars. Rhs must be positive.
248inline bool operator==(Align Lhs, uint64_t Rhs) {
249  ALIGN_CHECK_ISPOSITIVE(Rhs);
250  return Lhs.value() == Rhs;
251}
252inline bool operator!=(Align Lhs, uint64_t Rhs) {
253  ALIGN_CHECK_ISPOSITIVE(Rhs);
254  return Lhs.value() != Rhs;
255}
256inline bool operator<=(Align Lhs, uint64_t Rhs) {
257  ALIGN_CHECK_ISPOSITIVE(Rhs);
258  return Lhs.value() <= Rhs;
259}
260inline bool operator>=(Align Lhs, uint64_t Rhs) {
261  ALIGN_CHECK_ISPOSITIVE(Rhs);
262  return Lhs.value() >= Rhs;
263}
264inline bool operator<(Align Lhs, uint64_t Rhs) {
265  ALIGN_CHECK_ISPOSITIVE(Rhs);
266  return Lhs.value() < Rhs;
267}
268inline bool operator>(Align Lhs, uint64_t Rhs) {
269  ALIGN_CHECK_ISPOSITIVE(Rhs);
270  return Lhs.value() > Rhs;
271}
272 
273/// Comparisons between MaybeAlign and scalars.
274inline bool operator==(MaybeAlign Lhs, uint64_t Rhs) {
275  return Lhs ? (*Lhs).value() == Rhs : Rhs == 0;
276}
277inline bool operator!=(MaybeAlign Lhs, uint64_t Rhs) {
278  return Lhs ? (*Lhs).value() != Rhs : Rhs != 0;
279}
280 
281/// Comparisons operators between Align.
282inline bool operator==(Align Lhs, Align Rhs) {
283  return Lhs.ShiftValue == Rhs.ShiftValue;
284}
285inline bool operator!=(Align Lhs, Align Rhs) {
286  return Lhs.ShiftValue != Rhs.ShiftValue;
287}
288inline bool operator<=(Align Lhs, Align Rhs) {
289  return Lhs.ShiftValue <= Rhs.ShiftValue;
290}
291inline bool operator>=(Align Lhs, Align Rhs) {
292  return Lhs.ShiftValue >= Rhs.ShiftValue;
293}
294inline bool operator<(Align Lhs, Align Rhs) {
295  return Lhs.ShiftValue < Rhs.ShiftValue;
296}
297inline bool operator>(Align Lhs, Align Rhs) {
298  return Lhs.ShiftValue > Rhs.ShiftValue;
299}
300 
301// Don't allow relational comparisons with MaybeAlign.
302bool operator<=(Align Lhs, MaybeAlign Rhs) = delete;
303bool operator>=(Align Lhs, MaybeAlign Rhs) = delete;
304bool operator<(Align Lhs, MaybeAlign Rhs) = delete;
305bool operator>(Align Lhs, MaybeAlign Rhs) = delete;
306 
307bool operator<=(MaybeAlign Lhs, Align Rhs) = delete;
308bool operator>=(MaybeAlign Lhs, Align Rhs) = delete;
309bool operator<(MaybeAlign Lhs, Align Rhs) = delete;
310bool operator>(MaybeAlign Lhs, Align Rhs) = delete;
311 
312bool operator<=(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
313bool operator>=(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
314bool operator<(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
315bool operator>(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
316 
317inline Align operator*(Align Lhs, uint64_t Rhs) {
318  assert(Rhs > 0 && "Rhs must be positive")((void)0);
319  return Align(Lhs.value() * Rhs);
320}
321 
322inline MaybeAlign operator*(MaybeAlign Lhs, uint64_t Rhs) {
323  assert(Rhs > 0 && "Rhs must be positive")((void)0);
324  return Lhs ? Lhs.getValue() * Rhs : MaybeAlign();
325}
326 
327inline Align operator/(Align Lhs, uint64_t Divisor) {
328  assert(llvm::isPowerOf2_64(Divisor) &&((void)0)
329         "Divisor must be positive and a power of 2")((void)0);
330  assert(Lhs != 1 && "Can't halve byte alignment")((void)0);
331  return Align(Lhs.value() / Divisor);
332}
333 
334inline MaybeAlign operator/(MaybeAlign Lhs, uint64_t Divisor) {
335  assert(llvm::isPowerOf2_64(Divisor) &&((void)0)
336         "Divisor must be positive and a power of 2")((void)0);
337  return Lhs ? Lhs.getValue() / Divisor : MaybeAlign();
338}
339 
340inline Align max(MaybeAlign Lhs, Align Rhs) {
341  return Lhs && *Lhs > Rhs ? *Lhs : Rhs;
342}
343 
344inline Align max(Align Lhs, MaybeAlign Rhs) {
345  return Rhs && *Rhs > Lhs ? *Rhs : Lhs;
346}
347 
348#ifndef NDEBUG1
349// For usage in LLVM_DEBUG macros.
350inline std::string DebugStr(const Align &A) {
351  return std::to_string(A.value());
352}
353// For usage in LLVM_DEBUG macros.
354inline std::string DebugStr(const MaybeAlign &MA) {
355  if (MA)
356    return std::to_string(MA->value());
357  return "None";
358}
359#endif // NDEBUG
360 
361#undef ALIGN_CHECK_ISPOSITIVE
362 
363} // namespace llvm
364 
365#endif // LLVM_SUPPORT_ALIGNMENT_H_