Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support/GenericDomTree.h
Warning:line 494, column 12
Called C++ object pointer is null

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 MemorySSAUpdater.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 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/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/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/libLLVM/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/libLLVM/../../../llvm/llvm/lib/Analysis/MemorySSAUpdater.cpp

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Analysis/MemorySSAUpdater.cpp

→
1//===-- MemorySSAUpdater.cpp - Memory SSA Updater--------------------===//
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 MemorySSAUpdater class.
10//
11//===----------------------------------------------------------------===//
12#include "llvm/Analysis/MemorySSAUpdater.h"
13#include "llvm/Analysis/LoopIterator.h"
14#include "llvm/ADT/STLExtras.h"
15#include "llvm/ADT/SetVector.h"
16#include "llvm/ADT/SmallPtrSet.h"
17#include "llvm/Analysis/IteratedDominanceFrontier.h"
18#include "llvm/Analysis/MemorySSA.h"
19#include "llvm/IR/BasicBlock.h"
20#include "llvm/IR/DataLayout.h"
21#include "llvm/IR/Dominators.h"
22#include "llvm/IR/GlobalVariable.h"
23#include "llvm/IR/IRBuilder.h"
24#include "llvm/IR/LLVMContext.h"
25#include "llvm/IR/Metadata.h"
26#include "llvm/IR/Module.h"
27#include "llvm/Support/Debug.h"
28#include "llvm/Support/FormattedStream.h"
29#include <algorithm>
30
31#define DEBUG_TYPE"memoryssa" "memoryssa"
32using namespace llvm;
33
34// This is the marker algorithm from "Simple and Efficient Construction of
35// Static Single Assignment Form"
36// The simple, non-marker algorithm places phi nodes at any join
37// Here, we place markers, and only place phi nodes if they end up necessary.
38// They are only necessary if they break a cycle (IE we recursively visit
39// ourselves again), or we discover, while getting the value of the operands,
40// that there are two or more definitions needing to be merged.
41// This still will leave non-minimal form in the case of irreducible control
42// flow, where phi nodes may be in cycles with themselves, but unnecessary.
43MemoryAccess *MemorySSAUpdater::getPreviousDefRecursive(
44 BasicBlock *BB,
45 DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> &CachedPreviousDef) {
46 // First, do a cache lookup. Without this cache, certain CFG structures
47 // (like a series of if statements) take exponential time to visit.
48 auto Cached = CachedPreviousDef.find(BB);
49 if (Cached != CachedPreviousDef.end())
50 return Cached->second;
51
52 // If this method is called from an unreachable block, return LoE.
53 if (!MSSA->DT->isReachableFromEntry(BB))
54 return MSSA->getLiveOnEntryDef();
55
56 if (BasicBlock *Pred = BB->getUniquePredecessor()) {
57 VisitedBlocks.insert(BB);
58 // Single predecessor case, just recurse, we can only have one definition.
59 MemoryAccess *Result = getPreviousDefFromEnd(Pred, CachedPreviousDef);
60 CachedPreviousDef.insert({BB, Result});
61 return Result;
62 }
63
64 if (VisitedBlocks.count(BB)) {
65 // We hit our node again, meaning we had a cycle, we must insert a phi
66 // node to break it so we have an operand. The only case this will
67 // insert useless phis is if we have irreducible control flow.
68 MemoryAccess *Result = MSSA->createMemoryPhi(BB);
69 CachedPreviousDef.insert({BB, Result});
70 return Result;
71 }
72
73 if (VisitedBlocks.insert(BB).second) {
74 // Mark us visited so we can detect a cycle
75 SmallVector<TrackingVH<MemoryAccess>, 8> PhiOps;
76
77 // Recurse to get the values in our predecessors for placement of a
78 // potential phi node. This will insert phi nodes if we cycle in order to
79 // break the cycle and have an operand.
80 bool UniqueIncomingAccess = true;
81 MemoryAccess *SingleAccess = nullptr;
82 for (auto *Pred : predecessors(BB)) {
83 if (MSSA->DT->isReachableFromEntry(Pred)) {
84 auto *IncomingAccess = getPreviousDefFromEnd(Pred, CachedPreviousDef);
85 if (!SingleAccess)
86 SingleAccess = IncomingAccess;
87 else if (IncomingAccess != SingleAccess)
88 UniqueIncomingAccess = false;
89 PhiOps.push_back(IncomingAccess);
90 } else
91 PhiOps.push_back(MSSA->getLiveOnEntryDef());
92 }
93
94 // Now try to simplify the ops to avoid placing a phi.
95 // This may return null if we never created a phi yet, that's okay
96 MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MSSA->getMemoryAccess(BB));
97
98 // See if we can avoid the phi by simplifying it.
99 auto *Result = tryRemoveTrivialPhi(Phi, PhiOps);
100 // If we couldn't simplify, we may have to create a phi
101 if (Result == Phi && UniqueIncomingAccess && SingleAccess) {
102 // A concrete Phi only exists if we created an empty one to break a cycle.
103 if (Phi) {
104 assert(Phi->operands().empty() && "Expected empty Phi")((void)0);
105 Phi->replaceAllUsesWith(SingleAccess);
106 removeMemoryAccess(Phi);
107 }
108 Result = SingleAccess;
109 } else if (Result == Phi && !(UniqueIncomingAccess && SingleAccess)) {
110 if (!Phi)
111 Phi = MSSA->createMemoryPhi(BB);
112
113 // See if the existing phi operands match what we need.
114 // Unlike normal SSA, we only allow one phi node per block, so we can't just
115 // create a new one.
116 if (Phi->getNumOperands() != 0) {
117 // FIXME: Figure out whether this is dead code and if so remove it.
118 if (!std::equal(Phi->op_begin(), Phi->op_end(), PhiOps.begin())) {
119 // These will have been filled in by the recursive read we did above.
120 llvm::copy(PhiOps, Phi->op_begin());
121 std::copy(pred_begin(BB), pred_end(BB), Phi->block_begin());
122 }
123 } else {
124 unsigned i = 0;
125 for (auto *Pred : predecessors(BB))
126 Phi->addIncoming(&*PhiOps[i++], Pred);
127 InsertedPHIs.push_back(Phi);
128 }
129 Result = Phi;
130 }
131
132 // Set ourselves up for the next variable by resetting visited state.
133 VisitedBlocks.erase(BB);
134 CachedPreviousDef.insert({BB, Result});
135 return Result;
136 }
137 llvm_unreachable("Should have hit one of the three cases above")__builtin_unreachable();
138}
139
140// This starts at the memory access, and goes backwards in the block to find the
141// previous definition. If a definition is not found the block of the access,
142// it continues globally, creating phi nodes to ensure we have a single
143// definition.
144MemoryAccess *MemorySSAUpdater::getPreviousDef(MemoryAccess *MA) {
145 if (auto *LocalResult = getPreviousDefInBlock(MA))
146 return LocalResult;
147 DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> CachedPreviousDef;
148 return getPreviousDefRecursive(MA->getBlock(), CachedPreviousDef);
149}
150
151// This starts at the memory access, and goes backwards in the block to the find
152// the previous definition. If the definition is not found in the block of the
153// access, it returns nullptr.
154MemoryAccess *MemorySSAUpdater::getPreviousDefInBlock(MemoryAccess *MA) {
155 auto *Defs = MSSA->getWritableBlockDefs(MA->getBlock());
156
157 // It's possible there are no defs, or we got handed the first def to start.
158 if (Defs) {
159 // If this is a def, we can just use the def iterators.
160 if (!isa<MemoryUse>(MA)) {
161 auto Iter = MA->getReverseDefsIterator();
162 ++Iter;
163 if (Iter != Defs->rend())
164 return &*Iter;
165 } else {
166 // Otherwise, have to walk the all access iterator.
167 auto End = MSSA->getWritableBlockAccesses(MA->getBlock())->rend();
168 for (auto &U : make_range(++MA->getReverseIterator(), End))
169 if (!isa<MemoryUse>(U))
170 return cast<MemoryAccess>(&U);
171 // Note that if MA comes before Defs->begin(), we won't hit a def.
172 return nullptr;
173 }
174 }
175 return nullptr;
176}
177
178// This starts at the end of block
179MemoryAccess *MemorySSAUpdater::getPreviousDefFromEnd(
180 BasicBlock *BB,
181 DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> &CachedPreviousDef) {
182 auto *Defs = MSSA->getWritableBlockDefs(BB);
183
184 if (Defs) {
185 CachedPreviousDef.insert({BB, &*Defs->rbegin()});
186 return &*Defs->rbegin();
187 }
188
189 return getPreviousDefRecursive(BB, CachedPreviousDef);
190}
191// Recurse over a set of phi uses to eliminate the trivial ones
192MemoryAccess *MemorySSAUpdater::recursePhi(MemoryAccess *Phi) {
193 if (!Phi)
194 return nullptr;
195 TrackingVH<MemoryAccess> Res(Phi);
196 SmallVector<TrackingVH<Value>, 8> Uses;
197 std::copy(Phi->user_begin(), Phi->user_end(), std::back_inserter(Uses));
198 for (auto &U : Uses)
199 if (MemoryPhi *UsePhi = dyn_cast<MemoryPhi>(&*U))
200 tryRemoveTrivialPhi(UsePhi);
201 return Res;
202}
203
204// Eliminate trivial phis
205// Phis are trivial if they are defined either by themselves, or all the same
206// argument.
207// IE phi(a, a) or b = phi(a, b) or c = phi(a, a, c)
208// We recursively try to remove them.
209MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi) {
210 assert(Phi && "Can only remove concrete Phi.")((void)0);
211 auto OperRange = Phi->operands();
212 return tryRemoveTrivialPhi(Phi, OperRange);
213}
214template <class RangeType>
215MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi,
216 RangeType &Operands) {
217 // Bail out on non-opt Phis.
218 if (NonOptPhis.count(Phi))
219 return Phi;
220
221 // Detect equal or self arguments
222 MemoryAccess *Same = nullptr;
223 for (auto &Op : Operands) {
224 // If the same or self, good so far
225 if (Op == Phi || Op == Same)
226 continue;
227 // not the same, return the phi since it's not eliminatable by us
228 if (Same)
229 return Phi;
230 Same = cast<MemoryAccess>(&*Op);
231 }
232 // Never found a non-self reference, the phi is undef
233 if (Same == nullptr)
234 return MSSA->getLiveOnEntryDef();
235 if (Phi) {
236 Phi->replaceAllUsesWith(Same);
237 removeMemoryAccess(Phi);
238 }
239
240 // We should only end up recursing in case we replaced something, in which
241 // case, we may have made other Phis trivial.
242 return recursePhi(Same);
243}
244
245void MemorySSAUpdater::insertUse(MemoryUse *MU, bool RenameUses) {
246 InsertedPHIs.clear();
247 MU->setDefiningAccess(getPreviousDef(MU));
248
249 // In cases without unreachable blocks, because uses do not create new
250 // may-defs, there are only two cases:
251 // 1. There was a def already below us, and therefore, we should not have
252 // created a phi node because it was already needed for the def.
253 //
254 // 2. There is no def below us, and therefore, there is no extra renaming work
255 // to do.
256
257 // In cases with unreachable blocks, where the unnecessary Phis were
258 // optimized out, adding the Use may re-insert those Phis. Hence, when
259 // inserting Uses outside of the MSSA creation process, and new Phis were
260 // added, rename all uses if we are asked.
261
262 if (!RenameUses && !InsertedPHIs.empty()) {
263 auto *Defs = MSSA->getBlockDefs(MU->getBlock());
264 (void)Defs;
265 assert((!Defs || (++Defs->begin() == Defs->end())) &&((void)0)
266 "Block may have only a Phi or no defs")((void)0);
267 }
268
269 if (RenameUses && InsertedPHIs.size()) {
270 SmallPtrSet<BasicBlock *, 16> Visited;
271 BasicBlock *StartBlock = MU->getBlock();
272
273 if (auto *Defs = MSSA->getWritableBlockDefs(StartBlock)) {
274 MemoryAccess *FirstDef = &*Defs->begin();
275 // Convert to incoming value if it's a memorydef. A phi *is* already an
276 // incoming value.
277 if (auto *MD = dyn_cast<MemoryDef>(FirstDef))
278 FirstDef = MD->getDefiningAccess();
279
280 MSSA->renamePass(MU->getBlock(), FirstDef, Visited);
281 }
282 // We just inserted a phi into this block, so the incoming value will
283 // become the phi anyway, so it does not matter what we pass.
284 for (auto &MP : InsertedPHIs)
285 if (MemoryPhi *Phi = cast_or_null<MemoryPhi>(MP))
286 MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
287 }
288}
289
290// Set every incoming edge {BB, MP->getBlock()} of MemoryPhi MP to NewDef.
291static void setMemoryPhiValueForBlock(MemoryPhi *MP, const BasicBlock *BB,
292 MemoryAccess *NewDef) {
293 // Replace any operand with us an incoming block with the new defining
294 // access.
295 int i = MP->getBasicBlockIndex(BB);
296 assert(i != -1 && "Should have found the basic block in the phi")((void)0);
297 // We can't just compare i against getNumOperands since one is signed and the
298 // other not. So use it to index into the block iterator.
299 for (auto BBIter = MP->block_begin() + i; BBIter != MP->block_end();
300 ++BBIter) {
301 if (*BBIter != BB)
302 break;
303 MP->setIncomingValue(i, NewDef);
304 ++i;
305 }
306}
307
308// A brief description of the algorithm:
309// First, we compute what should define the new def, using the SSA
310// construction algorithm.
311// Then, we update the defs below us (and any new phi nodes) in the graph to
312// point to the correct new defs, to ensure we only have one variable, and no
313// disconnected stores.
314void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
315 InsertedPHIs.clear();
316
317 // See if we had a local def, and if not, go hunting.
318 MemoryAccess *DefBefore = getPreviousDef(MD);
319 bool DefBeforeSameBlock = false;
320 if (DefBefore->getBlock() == MD->getBlock() &&
321 !(isa<MemoryPhi>(DefBefore) &&
322 llvm::is_contained(InsertedPHIs, DefBefore)))
323 DefBeforeSameBlock = true;
324
325 // There is a def before us, which means we can replace any store/phi uses
326 // of that thing with us, since we are in the way of whatever was there
327 // before.
328 // We now define that def's memorydefs and memoryphis
329 if (DefBeforeSameBlock) {
330 DefBefore->replaceUsesWithIf(MD, [MD](Use &U) {
331 // Leave the MemoryUses alone.
332 // Also make sure we skip ourselves to avoid self references.
333 User *Usr = U.getUser();
334 return !isa<MemoryUse>(Usr) && Usr != MD;
335 // Defs are automatically unoptimized when the user is set to MD below,
336 // because the isOptimized() call will fail to find the same ID.
337 });
338 }
339
340 // and that def is now our defining access.
341 MD->setDefiningAccess(DefBefore);
342
343 SmallVector<WeakVH, 8> FixupList(InsertedPHIs.begin(), InsertedPHIs.end());
344
345 SmallSet<WeakVH, 8> ExistingPhis;
346
347 // Remember the index where we may insert new phis.
348 unsigned NewPhiIndex = InsertedPHIs.size();
349 if (!DefBeforeSameBlock) {
350 // If there was a local def before us, we must have the same effect it
351 // did. Because every may-def is the same, any phis/etc we would create, it
352 // would also have created. If there was no local def before us, we
353 // performed a global update, and have to search all successors and make
354 // sure we update the first def in each of them (following all paths until
355 // we hit the first def along each path). This may also insert phi nodes.
356 // TODO: There are other cases we can skip this work, such as when we have a
357 // single successor, and only used a straight line of single pred blocks
358 // backwards to find the def. To make that work, we'd have to track whether
359 // getDefRecursive only ever used the single predecessor case. These types
360 // of paths also only exist in between CFG simplifications.
361
362 // If this is the first def in the block and this insert is in an arbitrary
363 // place, compute IDF and place phis.
364 SmallPtrSet<BasicBlock *, 2> DefiningBlocks;
365
366 // If this is the last Def in the block, we may need additional Phis.
367 // Compute IDF in all cases, as renaming needs to be done even when MD is
368 // not the last access, because it can introduce a new access past which a
369 // previous access was optimized; that access needs to be reoptimized.
370 DefiningBlocks.insert(MD->getBlock());
371 for (const auto &VH : InsertedPHIs)
372 if (const auto *RealPHI = cast_or_null<MemoryPhi>(VH))
373 DefiningBlocks.insert(RealPHI->getBlock());
374 ForwardIDFCalculator IDFs(*MSSA->DT);
375 SmallVector<BasicBlock *, 32> IDFBlocks;
376 IDFs.setDefiningBlocks(DefiningBlocks);
377 IDFs.calculate(IDFBlocks);
378 SmallVector<AssertingVH<MemoryPhi>, 4> NewInsertedPHIs;
379 for (auto *BBIDF : IDFBlocks) {
380 auto *MPhi = MSSA->getMemoryAccess(BBIDF);
381 if (!MPhi) {
382 MPhi = MSSA->createMemoryPhi(BBIDF);
383 NewInsertedPHIs.push_back(MPhi);
384 } else {
385 ExistingPhis.insert(MPhi);
386 }
387 // Add the phis created into the IDF blocks to NonOptPhis, so they are not
388 // optimized out as trivial by the call to getPreviousDefFromEnd below.
389 // Once they are complete, all these Phis are added to the FixupList, and
390 // removed from NonOptPhis inside fixupDefs(). Existing Phis in IDF may
391 // need fixing as well, and potentially be trivial before this insertion,
392 // hence add all IDF Phis. See PR43044.
393 NonOptPhis.insert(MPhi);
394 }
395 for (auto &MPhi : NewInsertedPHIs) {
396 auto *BBIDF = MPhi->getBlock();
397 for (auto *Pred : predecessors(BBIDF)) {
398 DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> CachedPreviousDef;
399 MPhi->addIncoming(getPreviousDefFromEnd(Pred, CachedPreviousDef), Pred);
400 }
401 }
402
403 // Re-take the index where we're adding the new phis, because the above call
404 // to getPreviousDefFromEnd, may have inserted into InsertedPHIs.
405 NewPhiIndex = InsertedPHIs.size();
406 for (auto &MPhi : NewInsertedPHIs) {
407 InsertedPHIs.push_back(&*MPhi);
408 FixupList.push_back(&*MPhi);
409 }
410
411 FixupList.push_back(MD);
412 }
413
414 // Remember the index where we stopped inserting new phis above, since the
415 // fixupDefs call in the loop below may insert more, that are already minimal.
416 unsigned NewPhiIndexEnd = InsertedPHIs.size();
417
418 while (!FixupList.empty()) {
419 unsigned StartingPHISize = InsertedPHIs.size();
420 fixupDefs(FixupList);
421 FixupList.clear();
422 // Put any new phis on the fixup list, and process them
423 FixupList.append(InsertedPHIs.begin() + StartingPHISize, InsertedPHIs.end());
424 }
425
426 // Optimize potentially non-minimal phis added in this method.
427 unsigned NewPhiSize = NewPhiIndexEnd - NewPhiIndex;
428 if (NewPhiSize)
429 tryRemoveTrivialPhis(ArrayRef<WeakVH>(&InsertedPHIs[NewPhiIndex], NewPhiSize));
430
431 // Now that all fixups are done, rename all uses if we are asked. Skip
432 // renaming for defs in unreachable blocks.
433 BasicBlock *StartBlock = MD->getBlock();
434 if (RenameUses && MSSA->getDomTree().getNode(StartBlock)) {
435 SmallPtrSet<BasicBlock *, 16> Visited;
436 // We are guaranteed there is a def in the block, because we just got it
437 // handed to us in this function.
438 MemoryAccess *FirstDef = &*MSSA->getWritableBlockDefs(StartBlock)->begin();
439 // Convert to incoming value if it's a memorydef. A phi *is* already an
440 // incoming value.
441 if (auto *MD = dyn_cast<MemoryDef>(FirstDef))
442 FirstDef = MD->getDefiningAccess();
443
444 MSSA->renamePass(MD->getBlock(), FirstDef, Visited);
445 // We just inserted a phi into this block, so the incoming value will become
446 // the phi anyway, so it does not matter what we pass.
447 for (auto &MP : InsertedPHIs) {
448 MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MP);
449 if (Phi)
450 MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
451 }
452 // Existing Phi blocks may need renaming too, if an access was previously
453 // optimized and the inserted Defs "covers" the Optimized value.
454 for (auto &MP : ExistingPhis) {
455 MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MP);
456 if (Phi)
457 MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
458 }
459 }
460}
461
462void MemorySSAUpdater::fixupDefs(const SmallVectorImpl<WeakVH> &Vars) {
463 SmallPtrSet<const BasicBlock *, 8> Seen;
464 SmallVector<const BasicBlock *, 16> Worklist;
465 for (auto &Var : Vars) {
466 MemoryAccess *NewDef = dyn_cast_or_null<MemoryAccess>(Var);
467 if (!NewDef)
468 continue;
469 // First, see if there is a local def after the operand.
470 auto *Defs = MSSA->getWritableBlockDefs(NewDef->getBlock());
471 auto DefIter = NewDef->getDefsIterator();
472
473 // The temporary Phi is being fixed, unmark it for not to optimize.
474 if (MemoryPhi *Phi = dyn_cast<MemoryPhi>(NewDef))
475 NonOptPhis.erase(Phi);
476
477 // If there is a local def after us, we only have to rename that.
478 if (++DefIter != Defs->end()) {
479 cast<MemoryDef>(DefIter)->setDefiningAccess(NewDef);
480 continue;
481 }
482
483 // Otherwise, we need to search down through the CFG.
484 // For each of our successors, handle it directly if their is a phi, or
485 // place on the fixup worklist.
486 for (const auto *S : successors(NewDef->getBlock())) {
487 if (auto *MP = MSSA->getMemoryAccess(S))
488 setMemoryPhiValueForBlock(MP, NewDef->getBlock(), NewDef);
489 else
490 Worklist.push_back(S);
491 }
492
493 while (!Worklist.empty()) {
494 const BasicBlock *FixupBlock = Worklist.back();
495 Worklist.pop_back();
496
497 // Get the first def in the block that isn't a phi node.
498 if (auto *Defs = MSSA->getWritableBlockDefs(FixupBlock)) {
499 auto *FirstDef = &*Defs->begin();
500 // The loop above and below should have taken care of phi nodes
501 assert(!isa<MemoryPhi>(FirstDef) &&((void)0)
502 "Should have already handled phi nodes!")((void)0);
503 // We are now this def's defining access, make sure we actually dominate
504 // it
505 assert(MSSA->dominates(NewDef, FirstDef) &&((void)0)
506 "Should have dominated the new access")((void)0);
507
508 // This may insert new phi nodes, because we are not guaranteed the
509 // block we are processing has a single pred, and depending where the
510 // store was inserted, it may require phi nodes below it.
511 cast<MemoryDef>(FirstDef)->setDefiningAccess(getPreviousDef(FirstDef));
512 return;
513 }
514 // We didn't find a def, so we must continue.
515 for (const auto *S : successors(FixupBlock)) {
516 // If there is a phi node, handle it.
517 // Otherwise, put the block on the worklist
518 if (auto *MP = MSSA->getMemoryAccess(S))
519 setMemoryPhiValueForBlock(MP, FixupBlock, NewDef);
520 else {
521 // If we cycle, we should have ended up at a phi node that we already
522 // processed. FIXME: Double check this
523 if (!Seen.insert(S).second)
524 continue;
525 Worklist.push_back(S);
526 }
527 }
528 }
529 }
530}
531
532void MemorySSAUpdater::removeEdge(BasicBlock *From, BasicBlock *To) {
533 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
534 MPhi->unorderedDeleteIncomingBlock(From);
535 tryRemoveTrivialPhi(MPhi);
536 }
537}
538
539void MemorySSAUpdater::removeDuplicatePhiEdgesBetween(const BasicBlock *From,
540 const BasicBlock *To) {
541 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
542 bool Found = false;
543 MPhi->unorderedDeleteIncomingIf([&](const MemoryAccess *, BasicBlock *B) {
544 if (From != B)
545 return false;
546 if (Found)
547 return true;
548 Found = true;
549 return false;
550 });
551 tryRemoveTrivialPhi(MPhi);
552 }
553}
554
555/// If all arguments of a MemoryPHI are defined by the same incoming
556/// argument, return that argument.
557static MemoryAccess *onlySingleValue(MemoryPhi *MP) {
558 MemoryAccess *MA = nullptr;
559
560 for (auto &Arg : MP->operands()) {
561 if (!MA)
562 MA = cast<MemoryAccess>(Arg);
563 else if (MA != Arg)
564 return nullptr;
565 }
566 return MA;
567}
568
569static MemoryAccess *getNewDefiningAccessForClone(MemoryAccess *MA,
570 const ValueToValueMapTy &VMap,
571 PhiToDefMap &MPhiMap,
572 bool CloneWasSimplified,
573 MemorySSA *MSSA) {
574 MemoryAccess *InsnDefining = MA;
575 if (MemoryDef *DefMUD = dyn_cast<MemoryDef>(InsnDefining)) {
576 if (!MSSA->isLiveOnEntryDef(DefMUD)) {
577 Instruction *DefMUDI = DefMUD->getMemoryInst();
578 assert(DefMUDI && "Found MemoryUseOrDef with no Instruction.")((void)0);
579 if (Instruction *NewDefMUDI =
580 cast_or_null<Instruction>(VMap.lookup(DefMUDI))) {
581 InsnDefining = MSSA->getMemoryAccess(NewDefMUDI);
582 if (!CloneWasSimplified)
583 assert(InsnDefining && "Defining instruction cannot be nullptr.")((void)0);
584 else if (!InsnDefining || isa<MemoryUse>(InsnDefining)) {
585 // The clone was simplified, it's no longer a MemoryDef, look up.
586 auto DefIt = DefMUD->getDefsIterator();
587 // Since simplified clones only occur in single block cloning, a
588 // previous definition must exist, otherwise NewDefMUDI would not
589 // have been found in VMap.
590 assert(DefIt != MSSA->getBlockDefs(DefMUD->getBlock())->begin() &&((void)0)
591 "Previous def must exist")((void)0);
592 InsnDefining = getNewDefiningAccessForClone(
593 &*(--DefIt), VMap, MPhiMap, CloneWasSimplified, MSSA);
594 }
595 }
596 }
597 } else {
598 MemoryPhi *DefPhi = cast<MemoryPhi>(InsnDefining);
599 if (MemoryAccess *NewDefPhi = MPhiMap.lookup(DefPhi))
600 InsnDefining = NewDefPhi;
601 }
602 assert(InsnDefining && "Defining instruction cannot be nullptr.")((void)0);
603 return InsnDefining;
604}
605
606void MemorySSAUpdater::cloneUsesAndDefs(BasicBlock *BB, BasicBlock *NewBB,
607 const ValueToValueMapTy &VMap,
608 PhiToDefMap &MPhiMap,
609 bool CloneWasSimplified) {
610 const MemorySSA::AccessList *Acc = MSSA->getBlockAccesses(BB);
611 if (!Acc)
612 return;
613 for (const MemoryAccess &MA : *Acc) {
614 if (const MemoryUseOrDef *MUD = dyn_cast<MemoryUseOrDef>(&MA)) {
615 Instruction *Insn = MUD->getMemoryInst();
616 // Entry does not exist if the clone of the block did not clone all
617 // instructions. This occurs in LoopRotate when cloning instructions
618 // from the old header to the old preheader. The cloned instruction may
619 // also be a simplified Value, not an Instruction (see LoopRotate).
620 // Also in LoopRotate, even when it's an instruction, due to it being
621 // simplified, it may be a Use rather than a Def, so we cannot use MUD as
622 // template. Calls coming from updateForClonedBlockIntoPred, ensure this.
623 if (Instruction *NewInsn =
624 dyn_cast_or_null<Instruction>(VMap.lookup(Insn))) {
625 MemoryAccess *NewUseOrDef = MSSA->createDefinedAccess(
626 NewInsn,
627 getNewDefiningAccessForClone(MUD->getDefiningAccess(), VMap,
628 MPhiMap, CloneWasSimplified, MSSA),
629 /*Template=*/CloneWasSimplified ? nullptr : MUD,
630 /*CreationMustSucceed=*/CloneWasSimplified ? false : true);
631 if (NewUseOrDef)
632 MSSA->insertIntoListsForBlock(NewUseOrDef, NewBB, MemorySSA::End);
633 }
634 }
635 }
636}
637
638void MemorySSAUpdater::updatePhisWhenInsertingUniqueBackedgeBlock(
639 BasicBlock *Header, BasicBlock *Preheader, BasicBlock *BEBlock) {
640 auto *MPhi = MSSA->getMemoryAccess(Header);
641 if (!MPhi)
642 return;
643
644 // Create phi node in the backedge block and populate it with the same
645 // incoming values as MPhi. Skip incoming values coming from Preheader.
646 auto *NewMPhi = MSSA->createMemoryPhi(BEBlock);
647 bool HasUniqueIncomingValue = true;
648 MemoryAccess *UniqueValue = nullptr;
649 for (unsigned I = 0, E = MPhi->getNumIncomingValues(); I != E; ++I) {
650 BasicBlock *IBB = MPhi->getIncomingBlock(I);
651 MemoryAccess *IV = MPhi->getIncomingValue(I);
652 if (IBB != Preheader) {
653 NewMPhi->addIncoming(IV, IBB);
654 if (HasUniqueIncomingValue) {
655 if (!UniqueValue)
656 UniqueValue = IV;
657 else if (UniqueValue != IV)
658 HasUniqueIncomingValue = false;
659 }
660 }
661 }
662
663 // Update incoming edges into MPhi. Remove all but the incoming edge from
664 // Preheader. Add an edge from NewMPhi
665 auto *AccFromPreheader = MPhi->getIncomingValueForBlock(Preheader);
666 MPhi->setIncomingValue(0, AccFromPreheader);
667 MPhi->setIncomingBlock(0, Preheader);
668 for (unsigned I = MPhi->getNumIncomingValues() - 1; I >= 1; --I)
669 MPhi->unorderedDeleteIncoming(I);
670 MPhi->addIncoming(NewMPhi, BEBlock);
671
672 // If NewMPhi is a trivial phi, remove it. Its use in the header MPhi will be
673 // replaced with the unique value.
674 tryRemoveTrivialPhi(NewMPhi);
675}
676
677void MemorySSAUpdater::updateForClonedLoop(const LoopBlocksRPO &LoopBlocks,
678 ArrayRef<BasicBlock *> ExitBlocks,
679 const ValueToValueMapTy &VMap,
680 bool IgnoreIncomingWithNoClones) {
681 PhiToDefMap MPhiMap;
682
683 auto FixPhiIncomingValues = [&](MemoryPhi *Phi, MemoryPhi *NewPhi) {
684 assert(Phi && NewPhi && "Invalid Phi nodes.")((void)0);
685 BasicBlock *NewPhiBB = NewPhi->getBlock();
686 SmallPtrSet<BasicBlock *, 4> NewPhiBBPreds(pred_begin(NewPhiBB),
687 pred_end(NewPhiBB));
688 for (unsigned It = 0, E = Phi->getNumIncomingValues(); It < E; ++It) {
689 MemoryAccess *IncomingAccess = Phi->getIncomingValue(It);
690 BasicBlock *IncBB = Phi->getIncomingBlock(It);
691
692 if (BasicBlock *NewIncBB = cast_or_null<BasicBlock>(VMap.lookup(IncBB)))
693 IncBB = NewIncBB;
694 else if (IgnoreIncomingWithNoClones)
695 continue;
696
697 // Now we have IncBB, and will need to add incoming from it to NewPhi.
698
699 // If IncBB is not a predecessor of NewPhiBB, then do not add it.
700 // NewPhiBB was cloned without that edge.
701 if (!NewPhiBBPreds.count(IncBB))
702 continue;
703
704 // Determine incoming value and add it as incoming from IncBB.
705 if (MemoryUseOrDef *IncMUD = dyn_cast<MemoryUseOrDef>(IncomingAccess)) {
706 if (!MSSA->isLiveOnEntryDef(IncMUD)) {
707 Instruction *IncI = IncMUD->getMemoryInst();
708 assert(IncI && "Found MemoryUseOrDef with no Instruction.")((void)0);
709 if (Instruction *NewIncI =
710 cast_or_null<Instruction>(VMap.lookup(IncI))) {
711 IncMUD = MSSA->getMemoryAccess(NewIncI);
712 assert(IncMUD &&((void)0)
713 "MemoryUseOrDef cannot be null, all preds processed.")((void)0);
714 }
715 }
716 NewPhi->addIncoming(IncMUD, IncBB);
717 } else {
718 MemoryPhi *IncPhi = cast<MemoryPhi>(IncomingAccess);
719 if (MemoryAccess *NewDefPhi = MPhiMap.lookup(IncPhi))
720 NewPhi->addIncoming(NewDefPhi, IncBB);
721 else
722 NewPhi->addIncoming(IncPhi, IncBB);
723 }
724 }
725 if (auto *SingleAccess = onlySingleValue(NewPhi)) {
726 MPhiMap[Phi] = SingleAccess;
727 removeMemoryAccess(NewPhi);
728 }
729 };
730
731 auto ProcessBlock = [&](BasicBlock *BB) {
732 BasicBlock *NewBlock = cast_or_null<BasicBlock>(VMap.lookup(BB));
733 if (!NewBlock)
734 return;
735
736 assert(!MSSA->getWritableBlockAccesses(NewBlock) &&((void)0)
737 "Cloned block should have no accesses")((void)0);
738
739 // Add MemoryPhi.
740 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB)) {
741 MemoryPhi *NewPhi = MSSA->createMemoryPhi(NewBlock);
742 MPhiMap[MPhi] = NewPhi;
743 }
744 // Update Uses and Defs.
745 cloneUsesAndDefs(BB, NewBlock, VMap, MPhiMap);
746 };
747
748 for (auto BB : llvm::concat<BasicBlock *const>(LoopBlocks, ExitBlocks))
749 ProcessBlock(BB);
750
751 for (auto BB : llvm::concat<BasicBlock *const>(LoopBlocks, ExitBlocks))
752 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB))
753 if (MemoryAccess *NewPhi = MPhiMap.lookup(MPhi))
754 FixPhiIncomingValues(MPhi, cast<MemoryPhi>(NewPhi));
755}
756
757void MemorySSAUpdater::updateForClonedBlockIntoPred(
758 BasicBlock *BB, BasicBlock *P1, const ValueToValueMapTy &VM) {
759 // All defs/phis from outside BB that are used in BB, are valid uses in P1.
760 // Since those defs/phis must have dominated BB, and also dominate P1.
761 // Defs from BB being used in BB will be replaced with the cloned defs from
762 // VM. The uses of BB's Phi (if it exists) in BB will be replaced by the
763 // incoming def into the Phi from P1.
764 // Instructions cloned into the predecessor are in practice sometimes
765 // simplified, so disable the use of the template, and create an access from
766 // scratch.
767 PhiToDefMap MPhiMap;
768 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(BB))
769 MPhiMap[MPhi] = MPhi->getIncomingValueForBlock(P1);
770 cloneUsesAndDefs(BB, P1, VM, MPhiMap, /*CloneWasSimplified=*/true);
771}
772
773template <typename Iter>
774void MemorySSAUpdater::privateUpdateExitBlocksForClonedLoop(
775 ArrayRef<BasicBlock *> ExitBlocks, Iter ValuesBegin, Iter ValuesEnd,
776 DominatorTree &DT) {
777 SmallVector<CFGUpdate, 4> Updates;
778 // Update/insert phis in all successors of exit blocks.
779 for (auto *Exit : ExitBlocks)
780 for (const ValueToValueMapTy *VMap : make_range(ValuesBegin, ValuesEnd))
781 if (BasicBlock *NewExit = cast_or_null<BasicBlock>(VMap->lookup(Exit))) {
782 BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0);
783 Updates.push_back({DT.Insert, NewExit, ExitSucc});
784 }
785 applyInsertUpdates(Updates, DT);
786}
787
788void MemorySSAUpdater::updateExitBlocksForClonedLoop(
789 ArrayRef<BasicBlock *> ExitBlocks, const ValueToValueMapTy &VMap,
790 DominatorTree &DT) {
791 const ValueToValueMapTy *const Arr[] = {&VMap};
792 privateUpdateExitBlocksForClonedLoop(ExitBlocks, std::begin(Arr),
793 std::end(Arr), DT);
794}
795
796void MemorySSAUpdater::updateExitBlocksForClonedLoop(
797 ArrayRef<BasicBlock *> ExitBlocks,
798 ArrayRef<std::unique_ptr<ValueToValueMapTy>> VMaps, DominatorTree &DT) {
799 auto GetPtr = [&](const std::unique_ptr<ValueToValueMapTy> &I) {
800 return I.get();
801 };
802 using MappedIteratorType =
803 mapped_iterator<const std::unique_ptr<ValueToValueMapTy> *,
804 decltype(GetPtr)>;
805 auto MapBegin = MappedIteratorType(VMaps.begin(), GetPtr);
806 auto MapEnd = MappedIteratorType(VMaps.end(), GetPtr);
807 privateUpdateExitBlocksForClonedLoop(ExitBlocks, MapBegin, MapEnd, DT);
808}
809
810void MemorySSAUpdater::applyUpdates(ArrayRef<CFGUpdate> Updates,
811 DominatorTree &DT, bool UpdateDT) {
812 SmallVector<CFGUpdate, 4> DeleteUpdates;
813 SmallVector<CFGUpdate, 4> RevDeleteUpdates;
814 SmallVector<CFGUpdate, 4> InsertUpdates;
815 for (auto &Update : Updates) {
816 if (Update.getKind() == DT.Insert)
817 InsertUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
818 else {
819 DeleteUpdates.push_back({DT.Delete, Update.getFrom(), Update.getTo()});
820 RevDeleteUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
821 }
822 }
823
824 if (!DeleteUpdates.empty()) {
825 if (!UpdateDT) {
826 SmallVector<CFGUpdate, 0> Empty;
827 // Deletes are reversed applied, because this CFGView is pretending the
828 // deletes did not happen yet, hence the edges still exist.
829 DT.applyUpdates(Empty, RevDeleteUpdates);
830 } else {
831 // Apply all updates, with the RevDeleteUpdates as PostCFGView.
832 DT.applyUpdates(Updates, RevDeleteUpdates);
833 }
834
835 // Note: the MSSA update below doesn't distinguish between a GD with
836 // (RevDelete,false) and (Delete, true), but this matters for the DT
837 // updates above; for "children" purposes they are equivalent; but the
838 // updates themselves convey the desired update, used inside DT only.
839 GraphDiff<BasicBlock *> GD(RevDeleteUpdates);
840 applyInsertUpdates(InsertUpdates, DT, &GD);
841 // Update DT to redelete edges; this matches the real CFG so we can perform
842 // the standard update without a postview of the CFG.
843 DT.applyUpdates(DeleteUpdates);
844 } else {
845 if (UpdateDT)
846 DT.applyUpdates(Updates);
847 GraphDiff<BasicBlock *> GD;
848 applyInsertUpdates(InsertUpdates, DT, &GD);
849 }
850
851 // Update for deleted edges
852 for (auto &Update : DeleteUpdates)
853 removeEdge(Update.getFrom(), Update.getTo());
854}
855
856void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
857 DominatorTree &DT) {
858 GraphDiff<BasicBlock *> GD;
859 applyInsertUpdates(Updates, DT, &GD);
860}
861
862void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
863 DominatorTree &DT,
864 const GraphDiff<BasicBlock *> *GD) {
865 // Get recursive last Def, assuming well formed MSSA and updated DT.
866 auto GetLastDef = [&](BasicBlock *BB) -> MemoryAccess * {
867 while (true) {
868 MemorySSA::DefsList *Defs = MSSA->getWritableBlockDefs(BB);
869 // Return last Def or Phi in BB, if it exists.
870 if (Defs)
871 return &*(--Defs->end());
872
873 // Check number of predecessors, we only care if there's more than one.
874 unsigned Count = 0;
875 BasicBlock *Pred = nullptr;
876 for (auto *Pi : GD->template getChildren</*InverseEdge=*/true>(BB)) {
877 Pred = Pi;
878 Count++;
879 if (Count == 2)
880 break;
881 }
882
883 // If BB has multiple predecessors, get last definition from IDom.
884 if (Count != 1) {
885 // [SimpleLoopUnswitch] If BB is a dead block, about to be deleted, its
886 // DT is invalidated. Return LoE as its last def. This will be added to
887 // MemoryPhi node, and later deleted when the block is deleted.
888 if (!DT.getNode(BB))
889 return MSSA->getLiveOnEntryDef();
890 if (auto *IDom = DT.getNode(BB)->getIDom())
891 if (IDom->getBlock() != BB) {
892 BB = IDom->getBlock();
893 continue;
894 }
895 return MSSA->getLiveOnEntryDef();
896 } else {
897 // Single predecessor, BB cannot be dead. GetLastDef of Pred.
898 assert(Count == 1 && Pred && "Single predecessor expected.")((void)0);
899 // BB can be unreachable though, return LoE if that is the case.
900 if (!DT.getNode(BB))
901 return MSSA->getLiveOnEntryDef();
902 BB = Pred;
903 }
904 };
905 llvm_unreachable("Unable to get last definition.")__builtin_unreachable();
906 };
907
908 // Get nearest IDom given a set of blocks.
909 // TODO: this can be optimized by starting the search at the node with the
910 // lowest level (highest in the tree).
911 auto FindNearestCommonDominator =
912 [&](const SmallSetVector<BasicBlock *, 2> &BBSet) -> BasicBlock * {
913 BasicBlock *PrevIDom = *BBSet.begin();
914 for (auto *BB : BBSet)
13
←
Assuming '__begin1' is not equal to '__end1'
→
915 PrevIDom = DT.findNearestCommonDominator(PrevIDom, BB);
14
←
Calling 'DominatorTreeBase::findNearestCommonDominator'
→
916 return PrevIDom;
917 };
918
919 // Get all blocks that dominate PrevIDom, stop when reaching CurrIDom. Do not
920 // include CurrIDom.
921 auto GetNoLongerDomBlocks =
922 [&](BasicBlock *PrevIDom, BasicBlock *CurrIDom,
923 SmallVectorImpl<BasicBlock *> &BlocksPrevDom) {
924 if (PrevIDom == CurrIDom)
925 return;
926 BlocksPrevDom.push_back(PrevIDom);
927 BasicBlock *NextIDom = PrevIDom;
928 while (BasicBlock *UpIDom =
929 DT.getNode(NextIDom)->getIDom()->getBlock()) {
930 if (UpIDom == CurrIDom)
931 break;
932 BlocksPrevDom.push_back(UpIDom);
933 NextIDom = UpIDom;
934 }
935 };
936
937 // Map a BB to its predecessors: added + previously existing. To get a
938 // deterministic order, store predecessors as SetVectors. The order in each
939 // will be defined by the order in Updates (fixed) and the order given by
940 // children<> (also fixed). Since we further iterate over these ordered sets,
941 // we lose the information of multiple edges possibly existing between two
942 // blocks, so we'll keep and EdgeCount map for that.
943 // An alternate implementation could keep unordered set for the predecessors,
944 // traverse either Updates or children<> each time to get the deterministic
945 // order, and drop the usage of EdgeCount. This alternate approach would still
946 // require querying the maps for each predecessor, and children<> call has
947 // additional computation inside for creating the snapshot-graph predecessors.
948 // As such, we favor using a little additional storage and less compute time.
949 // This decision can be revisited if we find the alternative more favorable.
950
951 struct PredInfo {
952 SmallSetVector<BasicBlock *, 2> Added;
953 SmallSetVector<BasicBlock *, 2> Prev;
954 };
955 SmallDenseMap<BasicBlock *, PredInfo> PredMap;
956
957 for (auto &Edge : Updates) {
1
Assuming '__begin1' is equal to '__end1'
→
958 BasicBlock *BB = Edge.getTo();
959 auto &AddedBlockSet = PredMap[BB].Added;
960 AddedBlockSet.insert(Edge.getFrom());
961 }
962
963 // Store all existing predecessor for each BB, at least one must exist.
964 SmallDenseMap<std::pair<BasicBlock *, BasicBlock *>, int> EdgeCountMap;
965 SmallPtrSet<BasicBlock *, 2> NewBlocks;
966 for (auto &BBPredPair : PredMap) {
967 auto *BB = BBPredPair.first;
968 const auto &AddedBlockSet = BBPredPair.second.Added;
969 auto &PrevBlockSet = BBPredPair.second.Prev;
970 for (auto *Pi : GD->template getChildren</*InverseEdge=*/true>(BB)) {
971 if (!AddedBlockSet.count(Pi))
972 PrevBlockSet.insert(Pi);
973 EdgeCountMap[{Pi, BB}]++;
974 }
975
976 if (PrevBlockSet.empty()) {
977 assert(pred_size(BB) == AddedBlockSet.size() && "Duplicate edges added.")((void)0);
978 LLVM_DEBUG(do { } while (false)
979 dbgs()do { } while (false)
980 << "Adding a predecessor to a block with no predecessors. "do { } while (false)
981 "This must be an edge added to a new, likely cloned, block. "do { } while (false)
982 "Its memory accesses must be already correct, assuming completed "do { } while (false)
983 "via the updateExitBlocksForClonedLoop API. "do { } while (false)
984 "Assert a single such edge is added so no phi addition or "do { } while (false)
985 "additional processing is required.\n")do { } while (false);
986 assert(AddedBlockSet.size() == 1 &&((void)0)
987 "Can only handle adding one predecessor to a new block.")((void)0);
988 // Need to remove new blocks from PredMap. Remove below to not invalidate
989 // iterator here.
990 NewBlocks.insert(BB);
991 }
992 }
993 // Nothing to process for new/cloned blocks.
994 for (auto *BB : NewBlocks)
995 PredMap.erase(BB);
996
997 SmallVector<BasicBlock *, 16> BlocksWithDefsToReplace;
998 SmallVector<WeakVH, 8> InsertedPhis;
999
1000 // First create MemoryPhis in all blocks that don't have one. Create in the
1001 // order found in Updates, not in PredMap, to get deterministic numbering.
1002 for (auto &Edge : Updates) {
2
←
Assuming '__begin1' is equal to '__end1'
→
1003 BasicBlock *BB = Edge.getTo();
1004 if (PredMap.count(BB) && !MSSA->getMemoryAccess(BB))
1005 InsertedPhis.push_back(MSSA->createMemoryPhi(BB));
1006 }
1007
1008 // Now we'll fill in the MemoryPhis with the right incoming values.
1009 for (auto &BBPredPair : PredMap) {
1010 auto *BB = BBPredPair.first;
1011 const auto &PrevBlockSet = BBPredPair.second.Prev;
1012 const auto &AddedBlockSet = BBPredPair.second.Added;
1013 assert(!PrevBlockSet.empty() &&((void)0)
1014 "At least one previous predecessor must exist.")((void)0);
1015
1016 // TODO: if this becomes a bottleneck, we can save on GetLastDef calls by
1017 // keeping this map before the loop. We can reuse already populated entries
1018 // if an edge is added from the same predecessor to two different blocks,
1019 // and this does happen in rotate. Note that the map needs to be updated
1020 // when deleting non-necessary phis below, if the phi is in the map by
1021 // replacing the value with DefP1.
1022 SmallDenseMap<BasicBlock *, MemoryAccess *> LastDefAddedPred;
1023 for (auto *AddedPred : AddedBlockSet) {
3
←
Assuming '__begin2' is equal to '__end2'
→
1024 auto *DefPn = GetLastDef(AddedPred);
1025 assert(DefPn != nullptr && "Unable to find last definition.")((void)0);
1026 LastDefAddedPred[AddedPred] = DefPn;
1027 }
1028
1029 MemoryPhi *NewPhi = MSSA->getMemoryAccess(BB);
1030 // If Phi is not empty, add an incoming edge from each added pred. Must
1031 // still compute blocks with defs to replace for this block below.
1032 if (NewPhi->getNumOperands()) {
4
←
Assuming the condition is false
→
5
←
Taking false branch
→
1033 for (auto *Pred : AddedBlockSet) {
1034 auto *LastDefForPred = LastDefAddedPred[Pred];
1035 for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
1036 NewPhi->addIncoming(LastDefForPred, Pred);
1037 }
1038 } else {
1039 // Pick any existing predecessor and get its definition. All other
1040 // existing predecessors should have the same one, since no phi existed.
1041 auto *P1 = *PrevBlockSet.begin();
1042 MemoryAccess *DefP1 = GetLastDef(P1);
1043
1044 // Check DefP1 against all Defs in LastDefPredPair. If all the same,
1045 // nothing to add.
1046 bool InsertPhi = false;
1047 for (auto LastDefPredPair : LastDefAddedPred)
1048 if (DefP1 != LastDefPredPair.second) {
6
←
Assuming 'DefP1' is not equal to field 'second'
→
7
←
Taking true branch
→
1049 InsertPhi = true;
1050 break;
8
←
 Execution continues on line 1052
→
1051 }
1052 if (!InsertPhi
8.1
'InsertPhi' is true
8.1
'InsertPhi' is true
8.1
'InsertPhi' is true
) {
9
←
Taking false branch
→
1053 // Since NewPhi may be used in other newly added Phis, replace all uses
1054 // of NewPhi with the definition coming from all predecessors (DefP1),
1055 // before deleting it.
1056 NewPhi->replaceAllUsesWith(DefP1);
1057 removeMemoryAccess(NewPhi);
1058 continue;
1059 }
1060
1061 // Update Phi with new values for new predecessors and old value for all
1062 // other predecessors. Since AddedBlockSet and PrevBlockSet are ordered
1063 // sets, the order of entries in NewPhi is deterministic.
1064 for (auto *Pred : AddedBlockSet) {
10
←
Assuming '__begin3' is equal to '__end3'
→
1065 auto *LastDefForPred = LastDefAddedPred[Pred];
1066 for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
1067 NewPhi->addIncoming(LastDefForPred, Pred);
1068 }
1069 for (auto *Pred : PrevBlockSet)
11
←
Assuming '__begin3' is equal to '__end3'
→
1070 for (int I = 0, E = EdgeCountMap[{Pred, BB}]; I < E; ++I)
1071 NewPhi->addIncoming(DefP1, Pred);
1072 }
1073
1074 // Get all blocks that used to dominate BB and no longer do after adding
1075 // AddedBlockSet, where PrevBlockSet are the previously known predecessors.
1076 assert(DT.getNode(BB)->getIDom() && "BB does not have valid idom")((void)0);
1077 BasicBlock *PrevIDom = FindNearestCommonDominator(PrevBlockSet);
12
←
Calling 'operator()'
→
1078 assert(PrevIDom && "Previous IDom should exists")((void)0);
1079 BasicBlock *NewIDom = DT.getNode(BB)->getIDom()->getBlock();
1080 assert(NewIDom && "BB should have a new valid idom")((void)0);
1081 assert(DT.dominates(NewIDom, PrevIDom) &&((void)0)
1082 "New idom should dominate old idom")((void)0);
1083 GetNoLongerDomBlocks(PrevIDom, NewIDom, BlocksWithDefsToReplace);
1084 }
1085
1086 tryRemoveTrivialPhis(InsertedPhis);
1087 // Create the set of blocks that now have a definition. We'll use this to
1088 // compute IDF and add Phis there next.
1089 SmallVector<BasicBlock *, 8> BlocksToProcess;
1090 for (auto &VH : InsertedPhis)
1091 if (auto *MPhi = cast_or_null<MemoryPhi>(VH))
1092 BlocksToProcess.push_back(MPhi->getBlock());
1093
1094 // Compute IDF and add Phis in all IDF blocks that do not have one.
1095 SmallVector<BasicBlock *, 32> IDFBlocks;
1096 if (!BlocksToProcess.empty()) {
1097 ForwardIDFCalculator IDFs(DT, GD);
1098 SmallPtrSet<BasicBlock *, 16> DefiningBlocks(BlocksToProcess.begin(),
1099 BlocksToProcess.end());
1100 IDFs.setDefiningBlocks(DefiningBlocks);
1101 IDFs.calculate(IDFBlocks);
1102
1103 SmallSetVector<MemoryPhi *, 4> PhisToFill;
1104 // First create all needed Phis.
1105 for (auto *BBIDF : IDFBlocks)
1106 if (!MSSA->getMemoryAccess(BBIDF)) {
1107 auto *IDFPhi = MSSA->createMemoryPhi(BBIDF);
1108 InsertedPhis.push_back(IDFPhi);
1109 PhisToFill.insert(IDFPhi);
1110 }
1111 // Then update or insert their correct incoming values.
1112 for (auto *BBIDF : IDFBlocks) {
1113 auto *IDFPhi = MSSA->getMemoryAccess(BBIDF);
1114 assert(IDFPhi && "Phi must exist")((void)0);
1115 if (!PhisToFill.count(IDFPhi)) {
1116 // Update existing Phi.
1117 // FIXME: some updates may be redundant, try to optimize and skip some.
1118 for (unsigned I = 0, E = IDFPhi->getNumIncomingValues(); I < E; ++I)
1119 IDFPhi->setIncomingValue(I, GetLastDef(IDFPhi->getIncomingBlock(I)));
1120 } else {
1121 for (auto *Pi : GD->template getChildren</*InverseEdge=*/true>(BBIDF))
1122 IDFPhi->addIncoming(GetLastDef(Pi), Pi);
1123 }
1124 }
1125 }
1126
1127 // Now for all defs in BlocksWithDefsToReplace, if there are uses they no
1128 // longer dominate, replace those with the closest dominating def.
1129 // This will also update optimized accesses, as they're also uses.
1130 for (auto *BlockWithDefsToReplace : BlocksWithDefsToReplace) {
1131 if (auto DefsList = MSSA->getWritableBlockDefs(BlockWithDefsToReplace)) {
1132 for (auto &DefToReplaceUses : *DefsList) {
1133 BasicBlock *DominatingBlock = DefToReplaceUses.getBlock();
1134 Value::use_iterator UI = DefToReplaceUses.use_begin(),
1135 E = DefToReplaceUses.use_end();
1136 for (; UI != E;) {
1137 Use &U = *UI;
1138 ++UI;
1139 MemoryAccess *Usr = cast<MemoryAccess>(U.getUser());
1140 if (MemoryPhi *UsrPhi = dyn_cast<MemoryPhi>(Usr)) {
1141 BasicBlock *DominatedBlock = UsrPhi->getIncomingBlock(U);
1142 if (!DT.dominates(DominatingBlock, DominatedBlock))
1143 U.set(GetLastDef(DominatedBlock));
1144 } else {
1145 BasicBlock *DominatedBlock = Usr->getBlock();
1146 if (!DT.dominates(DominatingBlock, DominatedBlock)) {
1147 if (auto *DomBlPhi = MSSA->getMemoryAccess(DominatedBlock))
1148 U.set(DomBlPhi);
1149 else {
1150 auto *IDom = DT.getNode(DominatedBlock)->getIDom();
1151 assert(IDom && "Block must have a valid IDom.")((void)0);
1152 U.set(GetLastDef(IDom->getBlock()));
1153 }
1154 cast<MemoryUseOrDef>(Usr)->resetOptimized();
1155 }
1156 }
1157 }
1158 }
1159 }
1160 }
1161 tryRemoveTrivialPhis(InsertedPhis);
1162}
1163
1164// Move What before Where in the MemorySSA IR.
1165template <class WhereType>
1166void MemorySSAUpdater::moveTo(MemoryUseOrDef *What, BasicBlock *BB,
1167 WhereType Where) {
1168 // Mark MemoryPhi users of What not to be optimized.
1169 for (auto *U : What->users())
1170 if (MemoryPhi *PhiUser = dyn_cast<MemoryPhi>(U))
1171 NonOptPhis.insert(PhiUser);
1172
1173 // Replace all our users with our defining access.
1174 What->replaceAllUsesWith(What->getDefiningAccess());
1175
1176 // Let MemorySSA take care of moving it around in the lists.
1177 MSSA->moveTo(What, BB, Where);
1178
1179 // Now reinsert it into the IR and do whatever fixups needed.
1180 if (auto *MD = dyn_cast<MemoryDef>(What))
1181 insertDef(MD, /*RenameUses=*/true);
1182 else
1183 insertUse(cast<MemoryUse>(What), /*RenameUses=*/true);
1184
1185 // Clear dangling pointers. We added all MemoryPhi users, but not all
1186 // of them are removed by fixupDefs().
1187 NonOptPhis.clear();
1188}
1189
1190// Move What before Where in the MemorySSA IR.
1191void MemorySSAUpdater::moveBefore(MemoryUseOrDef *What, MemoryUseOrDef *Where) {
1192 moveTo(What, Where->getBlock(), Where->getIterator());
1193}
1194
1195// Move What after Where in the MemorySSA IR.
1196void MemorySSAUpdater::moveAfter(MemoryUseOrDef *What, MemoryUseOrDef *Where) {
1197 moveTo(What, Where->getBlock(), ++Where->getIterator());
1198}
1199
1200void MemorySSAUpdater::moveToPlace(MemoryUseOrDef *What, BasicBlock *BB,
1201 MemorySSA::InsertionPlace Where) {
1202 if (Where != MemorySSA::InsertionPlace::BeforeTerminator)
1203 return moveTo(What, BB, Where);
1204
1205 if (auto *Where = MSSA->getMemoryAccess(BB->getTerminator()))
1206 return moveBefore(What, Where);
1207 else
1208 return moveTo(What, BB, MemorySSA::InsertionPlace::End);
1209}
1210
1211// All accesses in To used to be in From. Move to end and update access lists.
1212void MemorySSAUpdater::moveAllAccesses(BasicBlock *From, BasicBlock *To,
1213 Instruction *Start) {
1214
1215 MemorySSA::AccessList *Accs = MSSA->getWritableBlockAccesses(From);
1216 if (!Accs)
1217 return;
1218
1219 assert(Start->getParent() == To && "Incorrect Start instruction")((void)0);
1220 MemoryAccess *FirstInNew = nullptr;
1221 for (Instruction &I : make_range(Start->getIterator(), To->end()))
1222 if ((FirstInNew = MSSA->getMemoryAccess(&I)))
1223 break;
1224 if (FirstInNew) {
1225 auto *MUD = cast<MemoryUseOrDef>(FirstInNew);
1226 do {
1227 auto NextIt = ++MUD->getIterator();
1228 MemoryUseOrDef *NextMUD = (!Accs || NextIt == Accs->end())
1229 ? nullptr
1230 : cast<MemoryUseOrDef>(&*NextIt);
1231 MSSA->moveTo(MUD, To, MemorySSA::End);
1232 // Moving MUD from Accs in the moveTo above, may delete Accs, so we need
1233 // to retrieve it again.
1234 Accs = MSSA->getWritableBlockAccesses(From);
1235 MUD = NextMUD;
1236 } while (MUD);
1237 }
1238
1239 // If all accesses were moved and only a trivial Phi remains, we try to remove
1240 // that Phi. This is needed when From is going to be deleted.
1241 auto *Defs = MSSA->getWritableBlockDefs(From);
1242 if (Defs && !Defs->empty())
1243 if (auto *Phi = dyn_cast<MemoryPhi>(&*Defs->begin()))
1244 tryRemoveTrivialPhi(Phi);
1245}
1246
1247void MemorySSAUpdater::moveAllAfterSpliceBlocks(BasicBlock *From,
1248 BasicBlock *To,
1249 Instruction *Start) {
1250 assert(MSSA->getBlockAccesses(To) == nullptr &&((void)0)
1251 "To block is expected to be free of MemoryAccesses.")((void)0);
1252 moveAllAccesses(From, To, Start);
1253 for (BasicBlock *Succ : successors(To))
1254 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Succ))
1255 MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
1256}
1257
1258void MemorySSAUpdater::moveAllAfterMergeBlocks(BasicBlock *From, BasicBlock *To,
1259 Instruction *Start) {
1260 assert(From->getUniquePredecessor() == To &&((void)0)
1261 "From block is expected to have a single predecessor (To).")((void)0);
1262 moveAllAccesses(From, To, Start);
1263 for (BasicBlock *Succ : successors(From))
1264 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Succ))
1265 MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
1266}
1267
1268void MemorySSAUpdater::wireOldPredecessorsToNewImmediatePredecessor(
1269 BasicBlock *Old, BasicBlock *New, ArrayRef<BasicBlock *> Preds,
1270 bool IdenticalEdgesWereMerged) {
1271 assert(!MSSA->getWritableBlockAccesses(New) &&((void)0)
1272 "Access list should be null for a new block.")((void)0);
1273 MemoryPhi *Phi = MSSA->getMemoryAccess(Old);
1274 if (!Phi)
1275 return;
1276 if (Old->hasNPredecessors(1)) {
1277 assert(pred_size(New) == Preds.size() &&((void)0)
1278 "Should have moved all predecessors.")((void)0);
1279 MSSA->moveTo(Phi, New, MemorySSA::Beginning);
1280 } else {
1281 assert(!Preds.empty() && "Must be moving at least one predecessor to the "((void)0)
1282 "new immediate predecessor.")((void)0);
1283 MemoryPhi *NewPhi = MSSA->createMemoryPhi(New);
1284 SmallPtrSet<BasicBlock *, 16> PredsSet(Preds.begin(), Preds.end());
1285 // Currently only support the case of removing a single incoming edge when
1286 // identical edges were not merged.
1287 if (!IdenticalEdgesWereMerged)
1288 assert(PredsSet.size() == Preds.size() &&((void)0)
1289 "If identical edges were not merged, we cannot have duplicate "((void)0)
1290 "blocks in the predecessors")((void)0);
1291 Phi->unorderedDeleteIncomingIf([&](MemoryAccess *MA, BasicBlock *B) {
1292 if (PredsSet.count(B)) {
1293 NewPhi->addIncoming(MA, B);
1294 if (!IdenticalEdgesWereMerged)
1295 PredsSet.erase(B);
1296 return true;
1297 }
1298 return false;
1299 });
1300 Phi->addIncoming(NewPhi, New);
1301 tryRemoveTrivialPhi(NewPhi);
1302 }
1303}
1304
1305void MemorySSAUpdater::removeMemoryAccess(MemoryAccess *MA, bool OptimizePhis) {
1306 assert(!MSSA->isLiveOnEntryDef(MA) &&((void)0)
1307 "Trying to remove the live on entry def")((void)0);
1308 // We can only delete phi nodes if they have no uses, or we can replace all
1309 // uses with a single definition.
1310 MemoryAccess *NewDefTarget = nullptr;
1311 if (MemoryPhi *MP = dyn_cast<MemoryPhi>(MA)) {
1312 // Note that it is sufficient to know that all edges of the phi node have
1313 // the same argument. If they do, by the definition of dominance frontiers
1314 // (which we used to place this phi), that argument must dominate this phi,
1315 // and thus, must dominate the phi's uses, and so we will not hit the assert
1316 // below.
1317 NewDefTarget = onlySingleValue(MP);
1318 assert((NewDefTarget || MP->use_empty()) &&((void)0)
1319 "We can't delete this memory phi")((void)0);
1320 } else {
1321 NewDefTarget = cast<MemoryUseOrDef>(MA)->getDefiningAccess();
1322 }
1323
1324 SmallSetVector<MemoryPhi *, 4> PhisToCheck;
1325
1326 // Re-point the uses at our defining access
1327 if (!isa<MemoryUse>(MA) && !MA->use_empty()) {
1328 // Reset optimized on users of this store, and reset the uses.
1329 // A few notes:
1330 // 1. This is a slightly modified version of RAUW to avoid walking the
1331 // uses twice here.
1332 // 2. If we wanted to be complete, we would have to reset the optimized
1333 // flags on users of phi nodes if doing the below makes a phi node have all
1334 // the same arguments. Instead, we prefer users to removeMemoryAccess those
1335 // phi nodes, because doing it here would be N^3.
1336 if (MA->hasValueHandle())
1337 ValueHandleBase::ValueIsRAUWd(MA, NewDefTarget);
1338 // Note: We assume MemorySSA is not used in metadata since it's not really
1339 // part of the IR.
1340
1341 assert(NewDefTarget != MA && "Going into an infinite loop")((void)0);
1342 while (!MA->use_empty()) {
1343 Use &U = *MA->use_begin();
1344 if (auto *MUD = dyn_cast<MemoryUseOrDef>(U.getUser()))
1345 MUD->resetOptimized();
1346 if (OptimizePhis)
1347 if (MemoryPhi *MP = dyn_cast<MemoryPhi>(U.getUser()))
1348 PhisToCheck.insert(MP);
1349 U.set(NewDefTarget);
1350 }
1351 }
1352
1353 // The call below to erase will destroy MA, so we can't change the order we
1354 // are doing things here
1355 MSSA->removeFromLookups(MA);
1356 MSSA->removeFromLists(MA);
1357
1358 // Optionally optimize Phi uses. This will recursively remove trivial phis.
1359 if (!PhisToCheck.empty()) {
1360 SmallVector<WeakVH, 16> PhisToOptimize{PhisToCheck.begin(),
1361 PhisToCheck.end()};
1362 PhisToCheck.clear();
1363
1364 unsigned PhisSize = PhisToOptimize.size();
1365 while (PhisSize-- > 0)
1366 if (MemoryPhi *MP =
1367 cast_or_null<MemoryPhi>(PhisToOptimize.pop_back_val()))
1368 tryRemoveTrivialPhi(MP);
1369 }
1370}
1371
1372void MemorySSAUpdater::removeBlocks(
1373 const SmallSetVector<BasicBlock *, 8> &DeadBlocks) {
1374 // First delete all uses of BB in MemoryPhis.
1375 for (BasicBlock *BB : DeadBlocks) {
1376 Instruction *TI = BB->getTerminator();
1377 assert(TI && "Basic block expected to have a terminator instruction")((void)0);
1378 for (BasicBlock *Succ : successors(TI))
1379 if (!DeadBlocks.count(Succ))
1380 if (MemoryPhi *MP = MSSA->getMemoryAccess(Succ)) {
1381 MP->unorderedDeleteIncomingBlock(BB);
1382 tryRemoveTrivialPhi(MP);
1383 }
1384 // Drop all references of all accesses in BB
1385 if (MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB))
1386 for (MemoryAccess &MA : *Acc)
1387 MA.dropAllReferences();
1388 }
1389
1390 // Next, delete all memory accesses in each block
1391 for (BasicBlock *BB : DeadBlocks) {
1392 MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB);
1393 if (!Acc)
1394 continue;
1395 for (MemoryAccess &MA : llvm::make_early_inc_range(*Acc)) {
1396 MSSA->removeFromLookups(&MA);
1397 MSSA->removeFromLists(&MA);
1398 }
1399 }
1400}
1401
1402void MemorySSAUpdater::tryRemoveTrivialPhis(ArrayRef<WeakVH> UpdatedPHIs) {
1403 for (auto &VH : UpdatedPHIs)
1404 if (auto *MPhi = cast_or_null<MemoryPhi>(VH))
1405 tryRemoveTrivialPhi(MPhi);
1406}
1407
1408void MemorySSAUpdater::changeToUnreachable(const Instruction *I) {
1409 const BasicBlock *BB = I->getParent();
1410 // Remove memory accesses in BB for I and all following instructions.
1411 auto BBI = I->getIterator(), BBE = BB->end();
1412 // FIXME: If this becomes too expensive, iterate until the first instruction
1413 // with a memory access, then iterate over MemoryAccesses.
1414 while (BBI != BBE)
1415 removeMemoryAccess(&*(BBI++));
1416 // Update phis in BB's successors to remove BB.
1417 SmallVector<WeakVH, 16> UpdatedPHIs;
1418 for (const BasicBlock *Successor : successors(BB)) {
1419 removeDuplicatePhiEdgesBetween(BB, Successor);
1420 if (MemoryPhi *MPhi = MSSA->getMemoryAccess(Successor)) {
1421 MPhi->unorderedDeleteIncomingBlock(BB);
1422 UpdatedPHIs.push_back(MPhi);
1423 }
1424 }
1425 // Optimize trivial phis.
1426 tryRemoveTrivialPhis(UpdatedPHIs);
1427}
1428
1429MemoryAccess *MemorySSAUpdater::createMemoryAccessInBB(
1430 Instruction *I, MemoryAccess *Definition, const BasicBlock *BB,
1431 MemorySSA::InsertionPlace Point) {
1432 MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1433 MSSA->insertIntoListsForBlock(NewAccess, BB, Point);
1434 return NewAccess;
1435}
1436
1437MemoryUseOrDef *MemorySSAUpdater::createMemoryAccessBefore(
1438 Instruction *I, MemoryAccess *Definition, MemoryUseOrDef *InsertPt) {
1439 assert(I->getParent() == InsertPt->getBlock() &&((void)0)
1440 "New and old access must be in the same block")((void)0);
1441 MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1442 MSSA->insertIntoListsBefore(NewAccess, InsertPt->getBlock(),
1443 InsertPt->getIterator());
1444 return NewAccess;
1445}
1446
1447MemoryUseOrDef *MemorySSAUpdater::createMemoryAccessAfter(
1448 Instruction *I, MemoryAccess *Definition, MemoryAccess *InsertPt) {
1449 assert(I->getParent() == InsertPt->getBlock() &&((void)0)
1450 "New and old access must be in the same block")((void)0);
1451 MemoryUseOrDef *NewAccess = MSSA->createDefinedAccess(I, Definition);
1452 MSSA->insertIntoListsBefore(NewAccess, InsertPt->getBlock(),
1453 ++InsertPt->getIterator());
1454 return NewAccess;
1455}
←

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support/GenericDomTree.h

→
1//===- GenericDomTree.h - Generic dominator trees for graphs ----*- 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 a set of templates that efficiently compute a dominator
11/// tree over a generic graph. This is used typically in LLVM for fast
12/// dominance queries on the CFG, but is fully generic w.r.t. the underlying
13/// graph types.
14///
15/// Unlike ADT/* graph algorithms, generic dominator tree has more requirements
16/// on the graph's NodeRef. The NodeRef should be a pointer and,
17/// NodeRef->getParent() must return the parent node that is also a pointer.
18///
19/// FIXME: Maybe GenericDomTree needs a TreeTraits, instead of GraphTraits.
20///
21//===----------------------------------------------------------------------===//
22
23#ifndef LLVM_SUPPORT_GENERICDOMTREE_H
24#define LLVM_SUPPORT_GENERICDOMTREE_H
25
26#include "llvm/ADT/DenseMap.h"
27#include "llvm/ADT/GraphTraits.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/SmallPtrSet.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/Support/CFGDiff.h"
32#include "llvm/Support/CFGUpdate.h"
33#include "llvm/Support/raw_ostream.h"
34#include <algorithm>
35#include <cassert>
36#include <cstddef>
37#include <iterator>
38#include <memory>
39#include <type_traits>
40#include <utility>
41
42namespace llvm {
43
44template <typename NodeT, bool IsPostDom>
45class DominatorTreeBase;
46
47namespace DomTreeBuilder {
48template <typename DomTreeT>
49struct SemiNCAInfo;
50} // namespace DomTreeBuilder
51
52/// Base class for the actual dominator tree node.
53template <class NodeT> class DomTreeNodeBase {
54 friend class PostDominatorTree;
55 friend class DominatorTreeBase<NodeT, false>;
56 friend class DominatorTreeBase<NodeT, true>;
57 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase<NodeT, false>>;
58 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase<NodeT, true>>;
59
60 NodeT *TheBB;
61 DomTreeNodeBase *IDom;
62 unsigned Level;
63 SmallVector<DomTreeNodeBase *, 4> Children;
64 mutable unsigned DFSNumIn = ~0;
65 mutable unsigned DFSNumOut = ~0;
66
67 public:
68 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase *iDom)
69 : TheBB(BB), IDom(iDom), Level(IDom ? IDom->Level + 1 : 0) {}
70
71 using iterator = typename SmallVector<DomTreeNodeBase *, 4>::iterator;
72 using const_iterator =
73 typename SmallVector<DomTreeNodeBase *, 4>::const_iterator;
74
75 iterator begin() { return Children.begin(); }
76 iterator end() { return Children.end(); }
77 const_iterator begin() const { return Children.begin(); }
78 const_iterator end() const { return Children.end(); }
79
80 DomTreeNodeBase *const &back() const { return Children.back(); }
81 DomTreeNodeBase *&back() { return Children.back(); }
82
83 iterator_range<iterator> children() { return make_range(begin(), end()); }
84 iterator_range<const_iterator> children() const {
85 return make_range(begin(), end());
86 }
87
88 NodeT *getBlock() const { return TheBB; }
89 DomTreeNodeBase *getIDom() const { return IDom; }
90 unsigned getLevel() const { return Level; }
91
92 std::unique_ptr<DomTreeNodeBase> addChild(
93 std::unique_ptr<DomTreeNodeBase> C) {
94 Children.push_back(C.get());
95 return C;
96 }
97
98 bool isLeaf() const { return Children.empty(); }
99 size_t getNumChildren() const { return Children.size(); }
100
101 void clearAllChildren() { Children.clear(); }
102
103 bool compare(const DomTreeNodeBase *Other) const {
104 if (getNumChildren() != Other->getNumChildren())
105 return true;
106
107 if (Level != Other->Level) return true;
108
109 SmallPtrSet<const NodeT *, 4> OtherChildren;
110 for (const DomTreeNodeBase *I : *Other) {
111 const NodeT *Nd = I->getBlock();
112 OtherChildren.insert(Nd);
113 }
114
115 for (const DomTreeNodeBase *I : *this) {
116 const NodeT *N = I->getBlock();
117 if (OtherChildren.count(N) == 0)
118 return true;
119 }
120 return false;
121 }
122
123 void setIDom(DomTreeNodeBase *NewIDom) {
124 assert(IDom && "No immediate dominator?")((void)0);
125 if (IDom == NewIDom) return;
126
127 auto I = find(IDom->Children, this);
128 assert(I != IDom->Children.end() &&((void)0)
129 "Not in immediate dominator children set!")((void)0);
130 // I am no longer your child...
131 IDom->Children.erase(I);
132
133 // Switch to new dominator
134 IDom = NewIDom;
135 IDom->Children.push_back(this);
136
137 UpdateLevel();
138 }
139
140 /// getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes
141 /// in the dominator tree. They are only guaranteed valid if
142 /// updateDFSNumbers() has been called.
143 unsigned getDFSNumIn() const { return DFSNumIn; }
144 unsigned getDFSNumOut() const { return DFSNumOut; }
145
146private:
147 // Return true if this node is dominated by other. Use this only if DFS info
148 // is valid.
149 bool DominatedBy(const DomTreeNodeBase *other) const {
150 return this->DFSNumIn >= other->DFSNumIn &&
151 this->DFSNumOut <= other->DFSNumOut;
152 }
153
154 void UpdateLevel() {
155 assert(IDom)((void)0);
156 if (Level == IDom->Level + 1) return;
157
158 SmallVector<DomTreeNodeBase *, 64> WorkStack = {this};
159
160 while (!WorkStack.empty()) {
161 DomTreeNodeBase *Current = WorkStack.pop_back_val();
162 Current->Level = Current->IDom->Level + 1;
163
164 for (DomTreeNodeBase *C : *Current) {
165 assert(C->IDom)((void)0);
166 if (C->Level != C->IDom->Level + 1) WorkStack.push_back(C);
167 }
168 }
169 }
170};
171
172template <class NodeT>
173raw_ostream &operator<<(raw_ostream &O, const DomTreeNodeBase<NodeT> *Node) {
174 if (Node->getBlock())
175 Node->getBlock()->printAsOperand(O, false);
176 else
177 O << " <<exit node>>";
178
179 O << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "} ["
180 << Node->getLevel() << "]\n";
181
182 return O;
183}
184
185template <class NodeT>
186void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &O,
187 unsigned Lev) {
188 O.indent(2 * Lev) << "[" << Lev << "] " << N;
189 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
190 E = N->end();
191 I != E; ++I)
192 PrintDomTree<NodeT>(*I, O, Lev + 1);
193}
194
195namespace DomTreeBuilder {
196// The routines below are provided in a separate header but referenced here.
197template <typename DomTreeT>
198void Calculate(DomTreeT &DT);
199
200template <typename DomTreeT>
201void CalculateWithUpdates(DomTreeT &DT,
202 ArrayRef<typename DomTreeT::UpdateType> Updates);
203
204template <typename DomTreeT>
205void InsertEdge(DomTreeT &DT, typename DomTreeT::NodePtr From,
206 typename DomTreeT::NodePtr To);
207
208template <typename DomTreeT>
209void DeleteEdge(DomTreeT &DT, typename DomTreeT::NodePtr From,
210 typename DomTreeT::NodePtr To);
211
212template <typename DomTreeT>
213void ApplyUpdates(DomTreeT &DT,
214 GraphDiff<typename DomTreeT::NodePtr,
215 DomTreeT::IsPostDominator> &PreViewCFG,
216 GraphDiff<typename DomTreeT::NodePtr,
217 DomTreeT::IsPostDominator> *PostViewCFG);
218
219template <typename DomTreeT>
220bool Verify(const DomTreeT &DT, typename DomTreeT::VerificationLevel VL);
221} // namespace DomTreeBuilder
222
223/// Core dominator tree base class.
224///
225/// This class is a generic template over graph nodes. It is instantiated for
226/// various graphs in the LLVM IR or in the code generator.
227template <typename NodeT, bool IsPostDom>
228class DominatorTreeBase {
229 public:
230 static_assert(std::is_pointer<typename GraphTraits<NodeT *>::NodeRef>::value,
231 "Currently DominatorTreeBase supports only pointer nodes");
232 using NodeType = NodeT;
233 using NodePtr = NodeT *;
234 using ParentPtr = decltype(std::declval<NodeT *>()->getParent());
235 static_assert(std::is_pointer<ParentPtr>::value,
236 "Currently NodeT's parent must be a pointer type");
237 using ParentType = std::remove_pointer_t<ParentPtr>;
238 static constexpr bool IsPostDominator = IsPostDom;
239
240 using UpdateType = cfg::Update<NodePtr>;
241 using UpdateKind = cfg::UpdateKind;
242 static constexpr UpdateKind Insert = UpdateKind::Insert;
243 static constexpr UpdateKind Delete = UpdateKind::Delete;
244
245 enum class VerificationLevel { Fast, Basic, Full };
246
247protected:
248 // Dominators always have a single root, postdominators can have more.
249 SmallVector<NodeT *, IsPostDom ? 4 : 1> Roots;
250
251 using DomTreeNodeMapType =
252 DenseMap<NodeT *, std::unique_ptr<DomTreeNodeBase<NodeT>>>;
253 DomTreeNodeMapType DomTreeNodes;
254 DomTreeNodeBase<NodeT> *RootNode = nullptr;
255 ParentPtr Parent = nullptr;
256
257 mutable bool DFSInfoValid = false;
258 mutable unsigned int SlowQueries = 0;
259
260 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase>;
261
262 public:
263 DominatorTreeBase() {}
264
265 DominatorTreeBase(DominatorTreeBase &&Arg)
266 : Roots(std::move(Arg.Roots)),
267 DomTreeNodes(std::move(Arg.DomTreeNodes)),
268 RootNode(Arg.RootNode),
269 Parent(Arg.Parent),
270 DFSInfoValid(Arg.DFSInfoValid),
271 SlowQueries(Arg.SlowQueries) {
272 Arg.wipe();
273 }
274
275 DominatorTreeBase &operator=(DominatorTreeBase &&RHS) {
276 Roots = std::move(RHS.Roots);
277 DomTreeNodes = std::move(RHS.DomTreeNodes);
278 RootNode = RHS.RootNode;
279 Parent = RHS.Parent;
280 DFSInfoValid = RHS.DFSInfoValid;
281 SlowQueries = RHS.SlowQueries;
282 RHS.wipe();
283 return *this;
284 }
285
286 DominatorTreeBase(const DominatorTreeBase &) = delete;
287 DominatorTreeBase &operator=(const DominatorTreeBase &) = delete;
288
289 /// Iteration over roots.
290 ///
291 /// This may include multiple blocks if we are computing post dominators.
292 /// For forward dominators, this will always be a single block (the entry
293 /// block).
294 using root_iterator = typename SmallVectorImpl<NodeT *>::iterator;
295 using const_root_iterator = typename SmallVectorImpl<NodeT *>::const_iterator;
296
297 root_iterator root_begin() { return Roots.begin(); }
298 const_root_iterator root_begin() const { return Roots.begin(); }
299 root_iterator root_end() { return Roots.end(); }
300 const_root_iterator root_end() const { return Roots.end(); }
301
302 size_t root_size() const { return Roots.size(); }
303
304 iterator_range<root_iterator> roots() {
305 return make_range(root_begin(), root_end());
306 }
307 iterator_range<const_root_iterator> roots() const {
308 return make_range(root_begin(), root_end());
309 }
310
311 /// isPostDominator - Returns true if analysis based of postdoms
312 ///
313 bool isPostDominator() const { return IsPostDominator; }
16
←
Returning zero (loaded from 'IsPostDominator'), which participates in a condition later
→
314
315 /// compare - Return false if the other dominator tree base matches this
316 /// dominator tree base. Otherwise return true.
317 bool compare(const DominatorTreeBase &Other) const {
318 if (Parent != Other.Parent) return true;
319
320 if (Roots.size() != Other.Roots.size())
321 return true;
322
323 if (!std::is_permutation(Roots.begin(), Roots.end(), Other.Roots.begin()))
324 return true;
325
326 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
327 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
328 return true;
329
330 for (const auto &DomTreeNode : DomTreeNodes) {
331 NodeT *BB = DomTreeNode.first;
332 typename DomTreeNodeMapType::const_iterator OI =
333 OtherDomTreeNodes.find(BB);
334 if (OI == OtherDomTreeNodes.end())
335 return true;
336
337 DomTreeNodeBase<NodeT> &MyNd = *DomTreeNode.second;
338 DomTreeNodeBase<NodeT> &OtherNd = *OI->second;
339
340 if (MyNd.compare(&OtherNd))
341 return true;
342 }
343
344 return false;
345 }
346
347 /// getNode - return the (Post)DominatorTree node for the specified basic
348 /// block. This is the same as using operator[] on this class. The result
349 /// may (but is not required to) be null for a forward (backwards)
350 /// statically unreachable block.
351 DomTreeNodeBase<NodeT> *getNode(const NodeT *BB) const {
352 auto I = DomTreeNodes.find(BB);
353 if (I != DomTreeNodes.end())
23
←
Calling 'operator!='
→
29
←
Returning from 'operator!='
→
30
←
Taking true branch
→
354 return I->second.get();
31
←
Returning pointer
→
355 return nullptr;
356 }
357
358 /// See getNode.
359 DomTreeNodeBase<NodeT> *operator[](const NodeT *BB) const {
360 return getNode(BB);
361 }
362
363 /// getRootNode - This returns the entry node for the CFG of the function. If
364 /// this tree represents the post-dominance relations for a function, however,
365 /// this root may be a node with the block == NULL. This is the case when
366 /// there are multiple exit nodes from a particular function. Consumers of
367 /// post-dominance information must be capable of dealing with this
368 /// possibility.
369 ///
370 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
371 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
372
373 /// Get all nodes dominated by R, including R itself.
374 void getDescendants(NodeT *R, SmallVectorImpl<NodeT *> &Result) const {
375 Result.clear();
376 const DomTreeNodeBase<NodeT> *RN = getNode(R);
377 if (!RN)
378 return; // If R is unreachable, it will not be present in the DOM tree.
379 SmallVector<const DomTreeNodeBase<NodeT> *, 8> WL;
380 WL.push_back(RN);
381
382 while (!WL.empty()) {
383 const DomTreeNodeBase<NodeT> *N = WL.pop_back_val();
384 Result.push_back(N->getBlock());
385 WL.append(N->begin(), N->end());
386 }
387 }
388
389 /// properlyDominates - Returns true iff A dominates B and A != B.
390 /// Note that this is not a constant time operation!
391 ///
392 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
393 const DomTreeNodeBase<NodeT> *B) const {
394 if (!A || !B)
395 return false;
396 if (A == B)
397 return false;
398 return dominates(A, B);
399 }
400
401 bool properlyDominates(const NodeT *A, const NodeT *B) const;
402
403 /// isReachableFromEntry - Return true if A is dominated by the entry
404 /// block of the function containing it.
405 bool isReachableFromEntry(const NodeT *A) const {
406 assert(!this->isPostDominator() &&((void)0)
407 "This is not implemented for post dominators")((void)0);
408 return isReachableFromEntry(getNode(const_cast<NodeT *>(A)));
409 }
410
411 bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const { return A; }
412
413 /// dominates - Returns true iff A dominates B. Note that this is not a
414 /// constant time operation!
415 ///
416 bool dominates(const DomTreeNodeBase<NodeT> *A,
417 const DomTreeNodeBase<NodeT> *B) const {
418 // A node trivially dominates itself.
419 if (B == A)
420 return true;
421
422 // An unreachable node is dominated by anything.
423 if (!isReachableFromEntry(B))
424 return true;
425
426 // And dominates nothing.
427 if (!isReachableFromEntry(A))
428 return false;
429
430 if (B->getIDom() == A) return true;
431
432 if (A->getIDom() == B) return false;
433
434 // A can only dominate B if it is higher in the tree.
435 if (A->getLevel() >= B->getLevel()) return false;
436
437 // Compare the result of the tree walk and the dfs numbers, if expensive
438 // checks are enabled.
439#ifdef EXPENSIVE_CHECKS
440 assert((!DFSInfoValid ||((void)0)
441 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) &&((void)0)
442 "Tree walk disagrees with dfs numbers!")((void)0);
443#endif
444
445 if (DFSInfoValid)
446 return B->DominatedBy(A);
447
448 // If we end up with too many slow queries, just update the
449 // DFS numbers on the theory that we are going to keep querying.
450 SlowQueries++;
451 if (SlowQueries > 32) {
452 updateDFSNumbers();
453 return B->DominatedBy(A);
454 }
455
456 return dominatedBySlowTreeWalk(A, B);
457 }
458
459 bool dominates(const NodeT *A, const NodeT *B) const;
460
461 NodeT *getRoot() const {
462 assert(this->Roots.size() == 1 && "Should always have entry node!")((void)0);
463 return this->Roots[0];
464 }
465
466 /// Find nearest common dominator basic block for basic block A and B. A and B
467 /// must have tree nodes.
468 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) const {
469 assert(A && B && "Pointers are not valid")((void)0);
470 assert(A->getParent() == B->getParent() &&((void)0)
471 "Two blocks are not in same function")((void)0);
472
473 // If either A or B is a entry block then it is nearest common dominator
474 // (for forward-dominators).
475 if (!isPostDominator()) {
15
←
Calling 'DominatorTreeBase::isPostDominator'
→
17
←
Returning from 'DominatorTreeBase::isPostDominator'
→
18
←
Taking true branch
→
476 NodeT &Entry = A->getParent()->front();
477 if (A == &Entry || B == &Entry)
19
←
Assuming the condition is false
→
20
←
Assuming the condition is false
→
21
←
Taking false branch
→
478 return &Entry;
479 }
480
481 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
22
←
Calling 'DominatorTreeBase::getNode'
→
32
←
Returning from 'DominatorTreeBase::getNode'
→
33
←
'NodeA' initialized here
→
482 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
483 assert(NodeA && "A must be in the tree")((void)0);
484 assert(NodeB && "B must be in the tree")((void)0);
485
486 // Use level information to go up the tree until the levels match. Then
487 // continue going up til we arrive at the same node.
488 while (NodeA != NodeB) {
34
←
Assuming 'NodeA' is equal to 'NodeB'
→
35
←
Loop condition is false. Execution continues on line 494
→
489 if (NodeA->getLevel() < NodeB->getLevel()) std::swap(NodeA, NodeB);
490
491 NodeA = NodeA->IDom;
492 }
493
494 return NodeA->getBlock();
36
←
Called C++ object pointer is null
495 }
496
497 const NodeT *findNearestCommonDominator(const NodeT *A,
498 const NodeT *B) const {
499 // Cast away the const qualifiers here. This is ok since
500 // const is re-introduced on the return type.
501 return findNearestCommonDominator(const_cast<NodeT *>(A),
502 const_cast<NodeT *>(B));
503 }
504
505 bool isVirtualRoot(const DomTreeNodeBase<NodeT> *A) const {
506 return isPostDominator() && !A->getBlock();
507 }
508
509 //===--------------------------------------------------------------------===//
510 // API to update (Post)DominatorTree information based on modifications to
511 // the CFG...
512
513 /// Inform the dominator tree about a sequence of CFG edge insertions and
514 /// deletions and perform a batch update on the tree.
515 ///
516 /// This function should be used when there were multiple CFG updates after
517 /// the last dominator tree update. It takes care of performing the updates
518 /// in sync with the CFG and optimizes away the redundant operations that
519 /// cancel each other.
520 /// The functions expects the sequence of updates to be balanced. Eg.:
521 /// - {{Insert, A, B}, {Delete, A, B}, {Insert, A, B}} is fine, because
522 /// logically it results in a single insertions.
523 /// - {{Insert, A, B}, {Insert, A, B}} is invalid, because it doesn't make
524 /// sense to insert the same edge twice.
525 ///
526 /// What's more, the functions assumes that it's safe to ask every node in the
527 /// CFG about its children and inverse children. This implies that deletions
528 /// of CFG edges must not delete the CFG nodes before calling this function.
529 ///
530 /// The applyUpdates function can reorder the updates and remove redundant
531 /// ones internally. The batch updater is also able to detect sequences of
532 /// zero and exactly one update -- it's optimized to do less work in these
533 /// cases.
534 ///
535 /// Note that for postdominators it automatically takes care of applying
536 /// updates on reverse edges internally (so there's no need to swap the
537 /// From and To pointers when constructing DominatorTree::UpdateType).
538 /// The type of updates is the same for DomTreeBase<T> and PostDomTreeBase<T>
539 /// with the same template parameter T.
540 ///
541 /// \param Updates An unordered sequence of updates to perform. The current
542 /// CFG and the reverse of these updates provides the pre-view of the CFG.
543 ///
544 void applyUpdates(ArrayRef<UpdateType> Updates) {
545 GraphDiff<NodePtr, IsPostDominator> PreViewCFG(
546 Updates, /*ReverseApplyUpdates=*/true);
547 DomTreeBuilder::ApplyUpdates(*this, PreViewCFG, nullptr);
548 }
549
550 /// \param Updates An unordered sequence of updates to perform. The current
551 /// CFG and the reverse of these updates provides the pre-view of the CFG.
552 /// \param PostViewUpdates An unordered sequence of update to perform in order
553 /// to obtain a post-view of the CFG. The DT will be updated assuming the
554 /// obtained PostViewCFG is the desired end state.
555 void applyUpdates(ArrayRef<UpdateType> Updates,
556 ArrayRef<UpdateType> PostViewUpdates) {
557 if (Updates.empty()) {
558 GraphDiff<NodePtr, IsPostDom> PostViewCFG(PostViewUpdates);
559 DomTreeBuilder::ApplyUpdates(*this, PostViewCFG, &PostViewCFG);
560 } else {
561 // PreViewCFG needs to merge Updates and PostViewCFG. The updates in
562 // Updates need to be reversed, and match the direction in PostViewCFG.
563 // The PostViewCFG is created with updates reversed (equivalent to changes
564 // made to the CFG), so the PreViewCFG needs all the updates reverse
565 // applied.
566 SmallVector<UpdateType> AllUpdates(Updates.begin(), Updates.end());
567 append_range(AllUpdates, PostViewUpdates);
568 GraphDiff<NodePtr, IsPostDom> PreViewCFG(AllUpdates,
569 /*ReverseApplyUpdates=*/true);
570 GraphDiff<NodePtr, IsPostDom> PostViewCFG(PostViewUpdates);
571 DomTreeBuilder::ApplyUpdates(*this, PreViewCFG, &PostViewCFG);
572 }
573 }
574
575 /// Inform the dominator tree about a CFG edge insertion and update the tree.
576 ///
577 /// This function has to be called just before or just after making the update
578 /// on the actual CFG. There cannot be any other updates that the dominator
579 /// tree doesn't know about.
580 ///
581 /// Note that for postdominators it automatically takes care of inserting
582 /// a reverse edge internally (so there's no need to swap the parameters).
583 ///
584 void insertEdge(NodeT *From, NodeT *To) {
585 assert(From)((void)0);
586 assert(To)((void)0);
587 assert(From->getParent() == Parent)((void)0);
588 assert(To->getParent() == Parent)((void)0);
589 DomTreeBuilder::InsertEdge(*this, From, To);
590 }
591
592 /// Inform the dominator tree about a CFG edge deletion and update the tree.
593 ///
594 /// This function has to be called just after making the update on the actual
595 /// CFG. An internal functions checks if the edge doesn't exist in the CFG in
596 /// DEBUG mode. There cannot be any other updates that the
597 /// dominator tree doesn't know about.
598 ///
599 /// Note that for postdominators it automatically takes care of deleting
600 /// a reverse edge internally (so there's no need to swap the parameters).
601 ///
602 void deleteEdge(NodeT *From, NodeT *To) {
603 assert(From)((void)0);
604 assert(To)((void)0);
605 assert(From->getParent() == Parent)((void)0);
606 assert(To->getParent() == Parent)((void)0);
607 DomTreeBuilder::DeleteEdge(*this, From, To);
608 }
609
610 /// Add a new node to the dominator tree information.
611 ///
612 /// This creates a new node as a child of DomBB dominator node, linking it
613 /// into the children list of the immediate dominator.
614 ///
615 /// \param BB New node in CFG.
616 /// \param DomBB CFG node that is dominator for BB.
617 /// \returns New dominator tree node that represents new CFG node.
618 ///
619 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
620 assert(getNode(BB) == nullptr && "Block already in dominator tree!")((void)0);
621 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
622 assert(IDomNode && "Not immediate dominator specified for block!")((void)0);
623 DFSInfoValid = false;
624 return createChild(BB, IDomNode);
625 }
626
627 /// Add a new node to the forward dominator tree and make it a new root.
628 ///
629 /// \param BB New node in CFG.
630 /// \returns New dominator tree node that represents new CFG node.
631 ///
632 DomTreeNodeBase<NodeT> *setNewRoot(NodeT *BB) {
633 assert(getNode(BB) == nullptr && "Block already in dominator tree!")((void)0);
634 assert(!this->isPostDominator() &&((void)0)
635 "Cannot change root of post-dominator tree")((void)0);
636 DFSInfoValid = false;
637 DomTreeNodeBase<NodeT> *NewNode = createNode(BB);
638 if (Roots.empty()) {
639 addRoot(BB);
640 } else {
641 assert(Roots.size() == 1)((void)0);
642 NodeT *OldRoot = Roots.front();
643 auto &OldNode = DomTreeNodes[OldRoot];
644 OldNode = NewNode->addChild(std::move(DomTreeNodes[OldRoot]));
645 OldNode->IDom = NewNode;
646 OldNode->UpdateLevel();
647 Roots[0] = BB;
648 }
649 return RootNode = NewNode;
650 }
651
652 /// changeImmediateDominator - This method is used to update the dominator
653 /// tree information when a node's immediate dominator changes.
654 ///
655 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
656 DomTreeNodeBase<NodeT> *NewIDom) {
657 assert(N && NewIDom && "Cannot change null node pointers!")((void)0);
658 DFSInfoValid = false;
659 N->setIDom(NewIDom);
660 }
661
662 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
663 changeImmediateDominator(getNode(BB), getNode(NewBB));
664 }
665
666 /// eraseNode - Removes a node from the dominator tree. Block must not
667 /// dominate any other blocks. Removes node from its immediate dominator's
668 /// children list. Deletes dominator node associated with basic block BB.
669 void eraseNode(NodeT *BB) {
670 DomTreeNodeBase<NodeT> *Node = getNode(BB);
671 assert(Node && "Removing node that isn't in dominator tree.")((void)0);
672 assert(Node->isLeaf() && "Node is not a leaf node.")((void)0);
673
674 DFSInfoValid = false;
675
676 // Remove node from immediate dominator's children list.
677 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
678 if (IDom) {
679 const auto I = find(IDom->Children, Node);
680 assert(I != IDom->Children.end() &&((void)0)
681 "Not in immediate dominator children set!")((void)0);
682 // I am no longer your child...
683 IDom->Children.erase(I);
684 }
685
686 DomTreeNodes.erase(BB);
687
688 if (!IsPostDom) return;
689
690 // Remember to update PostDominatorTree roots.
691 auto RIt = llvm::find(Roots, BB);
692 if (RIt != Roots.end()) {
693 std::swap(*RIt, Roots.back());
694 Roots.pop_back();
695 }
696 }
697
698 /// splitBlock - BB is split and now it has one successor. Update dominator
699 /// tree to reflect this change.
700 void splitBlock(NodeT *NewBB) {
701 if (IsPostDominator)
702 Split<Inverse<NodeT *>>(NewBB);
703 else
704 Split<NodeT *>(NewBB);
705 }
706
707 /// print - Convert to human readable form
708 ///
709 void print(raw_ostream &O) const {
710 O << "=============================--------------------------------\n";
711 if (IsPostDominator)
712 O << "Inorder PostDominator Tree: ";
713 else
714 O << "Inorder Dominator Tree: ";
715 if (!DFSInfoValid)
716 O << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
717 O << "\n";
718
719 // The postdom tree can have a null root if there are no returns.
720 if (getRootNode()) PrintDomTree<NodeT>(getRootNode(), O, 1);
721 O << "Roots: ";
722 for (const NodePtr Block : Roots) {
723 Block->printAsOperand(O, false);
724 O << " ";
725 }
726 O << "\n";
727 }
728
729public:
730 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
731 /// dominator tree in dfs order.
732 void updateDFSNumbers() const {
733 if (DFSInfoValid) {
734 SlowQueries = 0;
735 return;
736 }
737
738 SmallVector<std::pair<const DomTreeNodeBase<NodeT> *,
739 typename DomTreeNodeBase<NodeT>::const_iterator>,
740 32> WorkStack;
741
742 const DomTreeNodeBase<NodeT> *ThisRoot = getRootNode();
743 assert((!Parent || ThisRoot) && "Empty constructed DomTree")((void)0);
744 if (!ThisRoot)
745 return;
746
747 // Both dominators and postdominators have a single root node. In the case
748 // case of PostDominatorTree, this node is a virtual root.
749 WorkStack.push_back({ThisRoot, ThisRoot->begin()});
750
751 unsigned DFSNum = 0;
752 ThisRoot->DFSNumIn = DFSNum++;
753
754 while (!WorkStack.empty()) {
755 const DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
756 const auto ChildIt = WorkStack.back().second;
757
758 // If we visited all of the children of this node, "recurse" back up the
759 // stack setting the DFOutNum.
760 if (ChildIt == Node->end()) {
761 Node->DFSNumOut = DFSNum++;
762 WorkStack.pop_back();
763 } else {
764 // Otherwise, recursively visit this child.
765 const DomTreeNodeBase<NodeT> *Child = *ChildIt;
766 ++WorkStack.back().second;
767
768 WorkStack.push_back({Child, Child->begin()});
769 Child->DFSNumIn = DFSNum++;
770 }
771 }
772
773 SlowQueries = 0;
774 DFSInfoValid = true;
775 }
776
777 /// recalculate - compute a dominator tree for the given function
778 void recalculate(ParentType &Func) {
779 Parent = &Func;
780 DomTreeBuilder::Calculate(*this);
781 }
782
783 void recalculate(ParentType &Func, ArrayRef<UpdateType> Updates) {
784 Parent = &Func;
785 DomTreeBuilder::CalculateWithUpdates(*this, Updates);
786 }
787
788 /// verify - checks if the tree is correct. There are 3 level of verification:
789 /// - Full -- verifies if the tree is correct by making sure all the
790 /// properties (including the parent and the sibling property)
791 /// hold.
792 /// Takes O(N^3) time.
793 ///
794 /// - Basic -- checks if the tree is correct, but compares it to a freshly
795 /// constructed tree instead of checking the sibling property.
796 /// Takes O(N^2) time.
797 ///
798 /// - Fast -- checks basic tree structure and compares it with a freshly
799 /// constructed tree.
800 /// Takes O(N^2) time worst case, but is faster in practise (same
801 /// as tree construction).
802 bool verify(VerificationLevel VL = VerificationLevel::Full) const {
803 return DomTreeBuilder::Verify(*this, VL);
804 }
805
806 void reset() {
807 DomTreeNodes.clear();
808 Roots.clear();
809 RootNode = nullptr;
810 Parent = nullptr;
811 DFSInfoValid = false;
812 SlowQueries = 0;
813 }
814
815protected:
816 void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
817
818 DomTreeNodeBase<NodeT> *createChild(NodeT *BB, DomTreeNodeBase<NodeT> *IDom) {
819 return (DomTreeNodes[BB] = IDom->addChild(
820 std::make_unique<DomTreeNodeBase<NodeT>>(BB, IDom)))
821 .get();
822 }
823
824 DomTreeNodeBase<NodeT> *createNode(NodeT *BB) {
825 return (DomTreeNodes[BB] =
826 std::make_unique<DomTreeNodeBase<NodeT>>(BB, nullptr))
827 .get();
828 }
829
830 // NewBB is split and now it has one successor. Update dominator tree to
831 // reflect this change.
832 template <class N>
833 void Split(typename GraphTraits<N>::NodeRef NewBB) {
834 using GraphT = GraphTraits<N>;
835 using NodeRef = typename GraphT::NodeRef;
836 assert(std::distance(GraphT::child_begin(NewBB),((void)0)
837 GraphT::child_end(NewBB)) == 1 &&((void)0)
838 "NewBB should have a single successor!")((void)0);
839 NodeRef NewBBSucc = *GraphT::child_begin(NewBB);
840
841 SmallVector<NodeRef, 4> PredBlocks(children<Inverse<N>>(NewBB));
842
843 assert(!PredBlocks.empty() && "No predblocks?")((void)0);
844
845 bool NewBBDominatesNewBBSucc = true;
846 for (auto Pred : children<Inverse<N>>(NewBBSucc)) {
847 if (Pred != NewBB && !dominates(NewBBSucc, Pred) &&
848 isReachableFromEntry(Pred)) {
849 NewBBDominatesNewBBSucc = false;
850 break;
851 }
852 }
853
854 // Find NewBB's immediate dominator and create new dominator tree node for
855 // NewBB.
856 NodeT *NewBBIDom = nullptr;
857 unsigned i = 0;
858 for (i = 0; i < PredBlocks.size(); ++i)
859 if (isReachableFromEntry(PredBlocks[i])) {
860 NewBBIDom = PredBlocks[i];
861 break;
862 }
863
864 // It's possible that none of the predecessors of NewBB are reachable;
865 // in that case, NewBB itself is unreachable, so nothing needs to be
866 // changed.
867 if (!NewBBIDom) return;
868
869 for (i = i + 1; i < PredBlocks.size(); ++i) {
870 if (isReachableFromEntry(PredBlocks[i]))
871 NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
872 }
873
874 // Create the new dominator tree node... and set the idom of NewBB.
875 DomTreeNodeBase<NodeT> *NewBBNode = addNewBlock(NewBB, NewBBIDom);
876
877 // If NewBB strictly dominates other blocks, then it is now the immediate
878 // dominator of NewBBSucc. Update the dominator tree as appropriate.
879 if (NewBBDominatesNewBBSucc) {
880 DomTreeNodeBase<NodeT> *NewBBSuccNode = getNode(NewBBSucc);
881 changeImmediateDominator(NewBBSuccNode, NewBBNode);
882 }
883 }
884
885 private:
886 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
887 const DomTreeNodeBase<NodeT> *B) const {
888 assert(A != B)((void)0);
889 assert(isReachableFromEntry(B))((void)0);
890 assert(isReachableFromEntry(A))((void)0);
891
892 const unsigned ALevel = A->getLevel();
893 const DomTreeNodeBase<NodeT> *IDom;
894
895 // Don't walk nodes above A's subtree. When we reach A's level, we must
896 // either find A or be in some other subtree not dominated by A.
897 while ((IDom = B->getIDom()) != nullptr && IDom->getLevel() >= ALevel)
898 B = IDom; // Walk up the tree
899
900 return B == A;
901 }
902
903 /// Wipe this tree's state without releasing any resources.
904 ///
905 /// This is essentially a post-move helper only. It leaves the object in an
906 /// assignable and destroyable state, but otherwise invalid.
907 void wipe() {
908 DomTreeNodes.clear();
909 RootNode = nullptr;
910 Parent = nullptr;
911 }
912};
913
914template <typename T>
915using DomTreeBase = DominatorTreeBase<T, false>;
916
917template <typename T>
918using PostDomTreeBase = DominatorTreeBase<T, true>;
919
920// These two functions are declared out of line as a workaround for building
921// with old (< r147295) versions of clang because of pr11642.
922template <typename NodeT, bool IsPostDom>
923bool DominatorTreeBase<NodeT, IsPostDom>::dominates(const NodeT *A,
924 const NodeT *B) const {
925 if (A == B)
926 return true;
927
928 // Cast away the const qualifiers here. This is ok since
929 // this function doesn't actually return the values returned
930 // from getNode.
931 return dominates(getNode(const_cast<NodeT *>(A)),
932 getNode(const_cast<NodeT *>(B)));
933}
934template <typename NodeT, bool IsPostDom>
935bool DominatorTreeBase<NodeT, IsPostDom>::properlyDominates(
936 const NodeT *A, const NodeT *B) const {
937 if (A == B)
938 return false;
939
940 // Cast away the const qualifiers here. This is ok since
941 // this function doesn't actually return the values returned
942 // from getNode.
943 return dominates(getNode(const_cast<NodeT *>(A)),
944 getNode(const_cast<NodeT *>(B)));
945}
946
947} // end namespace llvm
948
949#endif // LLVM_SUPPORT_GENERICDOMTREE_H
←

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT/DenseMap.h

1//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- 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 defines the DenseMap class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_ADT_DENSEMAP_H
14#define LLVM_ADT_DENSEMAP_H
15
16#include "llvm/ADT/DenseMapInfo.h"
17#include "llvm/ADT/EpochTracker.h"
18#include "llvm/Support/AlignOf.h"
19#include "llvm/Support/Compiler.h"
20#include "llvm/Support/MathExtras.h"
21#include "llvm/Support/MemAlloc.h"
22#include "llvm/Support/ReverseIteration.h"
23#include "llvm/Support/type_traits.h"
24#include <algorithm>
25#include <cassert>
26#include <cstddef>
27#include <cstring>
28#include <initializer_list>
29#include <iterator>
30#include <new>
31#include <type_traits>
32#include <utility>
33
34namespace llvm {
35
36namespace detail {
37
38// We extend a pair to allow users to override the bucket type with their own
39// implementation without requiring two members.
40template <typename KeyT, typename ValueT>
41struct DenseMapPair : public std::pair<KeyT, ValueT> {
42 using std::pair<KeyT, ValueT>::pair;
43
44 KeyT &getFirst() { return std::pair<KeyT, ValueT>::first; }
45 const KeyT &getFirst() const { return std::pair<KeyT, ValueT>::first; }
46 ValueT &getSecond() { return std::pair<KeyT, ValueT>::second; }
47 const ValueT &getSecond() const { return std::pair<KeyT, ValueT>::second; }
48};
49
50} // end namespace detail
51
52template <typename KeyT, typename ValueT,
53 typename KeyInfoT = DenseMapInfo<KeyT>,
54 typename Bucket = llvm::detail::DenseMapPair<KeyT, ValueT>,
55 bool IsConst = false>
56class DenseMapIterator;
57
58template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
59 typename BucketT>
60class DenseMapBase : public DebugEpochBase {
61 template <typename T>
62 using const_arg_type_t = typename const_pointer_or_const_ref<T>::type;
63
64public:
65 using size_type = unsigned;
66 using key_type = KeyT;
67 using mapped_type = ValueT;
68 using value_type = BucketT;
69
70 using iterator = DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT>;
71 using const_iterator =
72 DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT, true>;
73
74 inline iterator begin() {
75 // When the map is empty, avoid the overhead of advancing/retreating past
76 // empty buckets.
77 if (empty())
78 return end();
79 if (shouldReverseIterate<KeyT>())
80 return makeIterator(getBucketsEnd() - 1, getBuckets(), *this);
81 return makeIterator(getBuckets(), getBucketsEnd(), *this);
82 }
83 inline iterator end() {
84 return makeIterator(getBucketsEnd(), getBucketsEnd(), *this, true);
85 }
86 inline const_iterator begin() const {
87 if (empty())
88 return end();
89 if (shouldReverseIterate<KeyT>())
90 return makeConstIterator(getBucketsEnd() - 1, getBuckets(), *this);
91 return makeConstIterator(getBuckets(), getBucketsEnd(), *this);
92 }
93 inline const_iterator end() const {
94 return makeConstIterator(getBucketsEnd(), getBucketsEnd(), *this, true);
95 }
96
97 LLVM_NODISCARD[[clang::warn_unused_result]] bool empty() const {
98 return getNumEntries() == 0;
99 }
100 unsigned size() const { return getNumEntries(); }
101
102 /// Grow the densemap so that it can contain at least \p NumEntries items
103 /// before resizing again.
104 void reserve(size_type NumEntries) {
105 auto NumBuckets = getMinBucketToReserveForEntries(NumEntries);
106 incrementEpoch();
107 if (NumBuckets > getNumBuckets())
108 grow(NumBuckets);
109 }
110
111 void clear() {
112 incrementEpoch();
113 if (getNumEntries() == 0 && getNumTombstones() == 0) return;
114
115 // If the capacity of the array is huge, and the # elements used is small,
116 // shrink the array.
117 if (getNumEntries() * 4 < getNumBuckets() && getNumBuckets() > 64) {
118 shrink_and_clear();
119 return;
120 }
121
122 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
123 if (std::is_trivially_destructible<ValueT>::value) {
124 // Use a simpler loop when values don't need destruction.
125 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P)
126 P->getFirst() = EmptyKey;
127 } else {
128 unsigned NumEntries = getNumEntries();
129 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
130 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey)) {
131 if (!KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
132 P->getSecond().~ValueT();
133 --NumEntries;
134 }
135 P->getFirst() = EmptyKey;
136 }
137 }
138 assert(NumEntries == 0 && "Node count imbalance!")((void)0);
139 }
140 setNumEntries(0);
141 setNumTombstones(0);
142 }
143
144 /// Return 1 if the specified key is in the map, 0 otherwise.
145 size_type count(const_arg_type_t<KeyT> Val) const {
146 const BucketT *TheBucket;
147 return LookupBucketFor(Val, TheBucket) ? 1 : 0;
148 }
149
150 iterator find(const_arg_type_t<KeyT> Val) {
151 BucketT *TheBucket;
152 if (LookupBucketFor(Val, TheBucket))
153 return makeIterator(TheBucket,
154 shouldReverseIterate<KeyT>() ? getBuckets()
155 : getBucketsEnd(),
156 *this, true);
157 return end();
158 }
159 const_iterator find(const_arg_type_t<KeyT> Val) const {
160 const BucketT *TheBucket;
161 if (LookupBucketFor(Val, TheBucket))
162 return makeConstIterator(TheBucket,
163 shouldReverseIterate<KeyT>() ? getBuckets()
164 : getBucketsEnd(),
165 *this, true);
166 return end();
167 }
168
169 /// Alternate version of find() which allows a different, and possibly
170 /// less expensive, key type.
171 /// The DenseMapInfo is responsible for supplying methods
172 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
173 /// type used.
174 template<class LookupKeyT>
175 iterator find_as(const LookupKeyT &Val) {
176 BucketT *TheBucket;
177 if (LookupBucketFor(Val, TheBucket))
178 return makeIterator(TheBucket,
179 shouldReverseIterate<KeyT>() ? getBuckets()
180 : getBucketsEnd(),
181 *this, true);
182 return end();
183 }
184 template<class LookupKeyT>
185 const_iterator find_as(const LookupKeyT &Val) const {
186 const BucketT *TheBucket;
187 if (LookupBucketFor(Val, TheBucket))
188 return makeConstIterator(TheBucket,
189 shouldReverseIterate<KeyT>() ? getBuckets()
190 : getBucketsEnd(),
191 *this, true);
192 return end();
193 }
194
195 /// lookup - Return the entry for the specified key, or a default
196 /// constructed value if no such entry exists.
197 ValueT lookup(const_arg_type_t<KeyT> Val) const {
198 const BucketT *TheBucket;
199 if (LookupBucketFor(Val, TheBucket))
200 return TheBucket->getSecond();
201 return ValueT();
202 }
203
204 // Inserts key,value pair into the map if the key isn't already in the map.
205 // If the key is already in the map, it returns false and doesn't update the
206 // value.
207 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
208 return try_emplace(KV.first, KV.second);
209 }
210
211 // Inserts key,value pair into the map if the key isn't already in the map.
212 // If the key is already in the map, it returns false and doesn't update the
213 // value.
214 std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
215 return try_emplace(std::move(KV.first), std::move(KV.second));
216 }
217
218 // Inserts key,value pair into the map if the key isn't already in the map.
219 // The value is constructed in-place if the key is not in the map, otherwise
220 // it is not moved.
221 template <typename... Ts>
222 std::pair<iterator, bool> try_emplace(KeyT &&Key, Ts &&... Args) {
223 BucketT *TheBucket;
224 if (LookupBucketFor(Key, TheBucket))
225 return std::make_pair(makeIterator(TheBucket,
226 shouldReverseIterate<KeyT>()
227 ? getBuckets()
228 : getBucketsEnd(),
229 *this, true),
230 false); // Already in map.
231
232 // Otherwise, insert the new element.
233 TheBucket =
234 InsertIntoBucket(TheBucket, std::move(Key), std::forward<Ts>(Args)...);
235 return std::make_pair(makeIterator(TheBucket,
236 shouldReverseIterate<KeyT>()
237 ? getBuckets()
238 : getBucketsEnd(),
239 *this, true),
240 true);
241 }
242
243 // Inserts key,value pair into the map if the key isn't already in the map.
244 // The value is constructed in-place if the key is not in the map, otherwise
245 // it is not moved.
246 template <typename... Ts>
247 std::pair<iterator, bool> try_emplace(const KeyT &Key, Ts &&... Args) {
248 BucketT *TheBucket;
249 if (LookupBucketFor(Key, TheBucket))
250 return std::make_pair(makeIterator(TheBucket,
251 shouldReverseIterate<KeyT>()
252 ? getBuckets()
253 : getBucketsEnd(),
254 *this, true),
255 false); // Already in map.
256
257 // Otherwise, insert the new element.
258 TheBucket = InsertIntoBucket(TheBucket, Key, std::forward<Ts>(Args)...);
259 return std::make_pair(makeIterator(TheBucket,
260 shouldReverseIterate<KeyT>()
261 ? getBuckets()
262 : getBucketsEnd(),
263 *this, true),
264 true);
265 }
266
267 /// Alternate version of insert() which allows a different, and possibly
268 /// less expensive, key type.
269 /// The DenseMapInfo is responsible for supplying methods
270 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
271 /// type used.
272 template <typename LookupKeyT>
273 std::pair<iterator, bool> insert_as(std::pair<KeyT, ValueT> &&KV,
274 const LookupKeyT &Val) {
275 BucketT *TheBucket;
276 if (LookupBucketFor(Val, TheBucket))
277 return std::make_pair(makeIterator(TheBucket,
278 shouldReverseIterate<KeyT>()
279 ? getBuckets()
280 : getBucketsEnd(),
281 *this, true),
282 false); // Already in map.
283
284 // Otherwise, insert the new element.
285 TheBucket = InsertIntoBucketWithLookup(TheBucket, std::move(KV.first),
286 std::move(KV.second), Val);
287 return std::make_pair(makeIterator(TheBucket,
288 shouldReverseIterate<KeyT>()
289 ? getBuckets()
290 : getBucketsEnd(),
291 *this, true),
292 true);
293 }
294
295 /// insert - Range insertion of pairs.
296 template<typename InputIt>
297 void insert(InputIt I, InputIt E) {
298 for (; I != E; ++I)
299 insert(*I);
300 }
301
302 bool erase(const KeyT &Val) {
303 BucketT *TheBucket;
304 if (!LookupBucketFor(Val, TheBucket))
305 return false; // not in map.
306
307 TheBucket->getSecond().~ValueT();
308 TheBucket->getFirst() = getTombstoneKey();
309 decrementNumEntries();
310 incrementNumTombstones();
311 return true;
312 }
313 void erase(iterator I) {
314 BucketT *TheBucket = &*I;
315 TheBucket->getSecond().~ValueT();
316 TheBucket->getFirst() = getTombstoneKey();
317 decrementNumEntries();
318 incrementNumTombstones();
319 }
320
321 value_type& FindAndConstruct(const KeyT &Key) {
322 BucketT *TheBucket;
323 if (LookupBucketFor(Key, TheBucket))
324 return *TheBucket;
325
326 return *InsertIntoBucket(TheBucket, Key);
327 }
328
329 ValueT &operator[](const KeyT &Key) {
330 return FindAndConstruct(Key).second;
331 }
332
333 value_type& FindAndConstruct(KeyT &&Key) {
334 BucketT *TheBucket;
335 if (LookupBucketFor(Key, TheBucket))
336 return *TheBucket;
337
338 return *InsertIntoBucket(TheBucket, std::move(Key));
339 }
340
341 ValueT &operator[](KeyT &&Key) {
342 return FindAndConstruct(std::move(Key)).second;
343 }
344
345 /// isPointerIntoBucketsArray - Return true if the specified pointer points
346 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or
347 /// value in the DenseMap).
348 bool isPointerIntoBucketsArray(const void *Ptr) const {
349 return Ptr >= getBuckets() && Ptr < getBucketsEnd();
350 }
351
352 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
353 /// array. In conjunction with the previous method, this can be used to
354 /// determine whether an insertion caused the DenseMap to reallocate.
355 const void *getPointerIntoBucketsArray() const { return getBuckets(); }
356
357protected:
358 DenseMapBase() = default;
359
360 void destroyAll() {
361 if (getNumBuckets() == 0) // Nothing to do.
362 return;
363
364 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
365 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
366 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
367 !KeyInfoT::isEqual(P->getFirst(), TombstoneKey))
368 P->getSecond().~ValueT();
369 P->getFirst().~KeyT();
370 }
371 }
372
373 void initEmpty() {
374 setNumEntries(0);
375 setNumTombstones(0);
376
377 assert((getNumBuckets() & (getNumBuckets()-1)) == 0 &&((void)0)
378 "# initial buckets must be a power of two!")((void)0);
379 const KeyT EmptyKey = getEmptyKey();
380 for (BucketT *B = getBuckets(), *E = getBucketsEnd(); B != E; ++B)
381 ::new (&B->getFirst()) KeyT(EmptyKey);
382 }
383
384 /// Returns the number of buckets to allocate to ensure that the DenseMap can
385 /// accommodate \p NumEntries without need to grow().
386 unsigned getMinBucketToReserveForEntries(unsigned NumEntries) {
387 // Ensure that "NumEntries * 4 < NumBuckets * 3"
388 if (NumEntries == 0)
389 return 0;
390 // +1 is required because of the strict equality.
391 // For example if NumEntries is 48, we need to return 401.
392 return NextPowerOf2(NumEntries * 4 / 3 + 1);
393 }
394
395 void moveFromOldBuckets(BucketT *OldBucketsBegin, BucketT *OldBucketsEnd) {
396 initEmpty();
397
398 // Insert all the old elements.
399 const KeyT EmptyKey = getEmptyKey();
400 const KeyT TombstoneKey = getTombstoneKey();
401 for (BucketT *B = OldBucketsBegin, *E = OldBucketsEnd; B != E; ++B) {
402 if (!KeyInfoT::isEqual(B->getFirst(), EmptyKey) &&
403 !KeyInfoT::isEqual(B->getFirst(), TombstoneKey)) {
404 // Insert the key/value into the new table.
405 BucketT *DestBucket;
406 bool FoundVal = LookupBucketFor(B->getFirst(), DestBucket);
407 (void)FoundVal; // silence warning.
408 assert(!FoundVal && "Key already in new map?")((void)0);
409 DestBucket->getFirst() = std::move(B->getFirst());
410 ::new (&DestBucket->getSecond()) ValueT(std::move(B->getSecond()));
411 incrementNumEntries();
412
413 // Free the value.
414 B->getSecond().~ValueT();
415 }
416 B->getFirst().~KeyT();
417 }
418 }
419
420 template <typename OtherBaseT>
421 void copyFrom(
422 const DenseMapBase<OtherBaseT, KeyT, ValueT, KeyInfoT, BucketT> &other) {
423 assert(&other != this)((void)0);
424 assert(getNumBuckets() == other.getNumBuckets())((void)0);
425
426 setNumEntries(other.getNumEntries());
427 setNumTombstones(other.getNumTombstones());
428
429 if (std::is_trivially_copyable<KeyT>::value &&
430 std::is_trivially_copyable<ValueT>::value)
431 memcpy(reinterpret_cast<void *>(getBuckets()), other.getBuckets(),
432 getNumBuckets() * sizeof(BucketT));
433 else
434 for (size_t i = 0; i < getNumBuckets(); ++i) {
435 ::new (&getBuckets()[i].getFirst())
436 KeyT(other.getBuckets()[i].getFirst());
437 if (!KeyInfoT::isEqual(getBuckets()[i].getFirst(), getEmptyKey()) &&
438 !KeyInfoT::isEqual(getBuckets()[i].getFirst(), getTombstoneKey()))
439 ::new (&getBuckets()[i].getSecond())
440 ValueT(other.getBuckets()[i].getSecond());
441 }
442 }
443
444 static unsigned getHashValue(const KeyT &Val) {
445 return KeyInfoT::getHashValue(Val);
446 }
447
448 template<typename LookupKeyT>
449 static unsigned getHashValue(const LookupKeyT &Val) {
450 return KeyInfoT::getHashValue(Val);
451 }
452
453 static const KeyT getEmptyKey() {
454 static_assert(std::is_base_of<DenseMapBase, DerivedT>::value,
455 "Must pass the derived type to this template!");
456 return KeyInfoT::getEmptyKey();
457 }
458
459 static const KeyT getTombstoneKey() {
460 return KeyInfoT::getTombstoneKey();
461 }
462
463private:
464 iterator makeIterator(BucketT *P, BucketT *E,
465 DebugEpochBase &Epoch,
466 bool NoAdvance=false) {
467 if (shouldReverseIterate<KeyT>()) {
468 BucketT *B = P == getBucketsEnd() ? getBuckets() : P + 1;
469 return iterator(B, E, Epoch, NoAdvance);
470 }
471 return iterator(P, E, Epoch, NoAdvance);
472 }
473
474 const_iterator makeConstIterator(const BucketT *P, const BucketT *E,
475 const DebugEpochBase &Epoch,
476 const bool NoAdvance=false) const {
477 if (shouldReverseIterate<KeyT>()) {
478 const BucketT *B = P == getBucketsEnd() ? getBuckets() : P + 1;
479 return const_iterator(B, E, Epoch, NoAdvance);
480 }
481 return const_iterator(P, E, Epoch, NoAdvance);
482 }
483
484 unsigned getNumEntries() const {
485 return static_cast<const DerivedT *>(this)->getNumEntries();
486 }
487
488 void setNumEntries(unsigned Num) {
489 static_cast<DerivedT *>(this)->setNumEntries(Num);
490 }
491
492 void incrementNumEntries() {
493 setNumEntries(getNumEntries() + 1);
494 }
495
496 void decrementNumEntries() {
497 setNumEntries(getNumEntries() - 1);
498 }
499
500 unsigned getNumTombstones() const {
501 return static_cast<const DerivedT *>(this)->getNumTombstones();
502 }
503
504 void setNumTombstones(unsigned Num) {
505 static_cast<DerivedT *>(this)->setNumTombstones(Num);
506 }
507
508 void incrementNumTombstones() {
509 setNumTombstones(getNumTombstones() + 1);
510 }
511
512 void decrementNumTombstones() {
513 setNumTombstones(getNumTombstones() - 1);
514 }
515
516 const BucketT *getBuckets() const {
517 return static_cast<const DerivedT *>(this)->getBuckets();
518 }
519
520 BucketT *getBuckets() {
521 return static_cast<DerivedT *>(this)->getBuckets();
522 }
523
524 unsigned getNumBuckets() const {
525 return static_cast<const DerivedT *>(this)->getNumBuckets();
526 }
527
528 BucketT *getBucketsEnd() {
529 return getBuckets() + getNumBuckets();
530 }
531
532 const BucketT *getBucketsEnd() const {
533 return getBuckets() + getNumBuckets();
534 }
535
536 void grow(unsigned AtLeast) {
537 static_cast<DerivedT *>(this)->grow(AtLeast);
538 }
539
540 void shrink_and_clear() {
541 static_cast<DerivedT *>(this)->shrink_and_clear();
542 }
543
544 template <typename KeyArg, typename... ValueArgs>
545 BucketT *InsertIntoBucket(BucketT *TheBucket, KeyArg &&Key,
546 ValueArgs &&... Values) {
547 TheBucket = InsertIntoBucketImpl(Key, Key, TheBucket);
548
549 TheBucket->getFirst() = std::forward<KeyArg>(Key);
550 ::new (&TheBucket->getSecond()) ValueT(std::forward<ValueArgs>(Values)...);
551 return TheBucket;
552 }
553
554 template <typename LookupKeyT>
555 BucketT *InsertIntoBucketWithLookup(BucketT *TheBucket, KeyT &&Key,
556 ValueT &&Value, LookupKeyT &Lookup) {
557 TheBucket = InsertIntoBucketImpl(Key, Lookup, TheBucket);
558
559 TheBucket->getFirst() = std::move(Key);
560 ::new (&TheBucket->getSecond()) ValueT(std::move(Value));
561 return TheBucket;
562 }
563
564 template <typename LookupKeyT>
565 BucketT *InsertIntoBucketImpl(const KeyT &Key, const LookupKeyT &Lookup,
566 BucketT *TheBucket) {
567 incrementEpoch();
568
569 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
570 // the buckets are empty (meaning that many are filled with tombstones),
571 // grow the table.
572 //
573 // The later case is tricky. For example, if we had one empty bucket with
574 // tons of tombstones, failing lookups (e.g. for insertion) would have to
575 // probe almost the entire table until it found the empty bucket. If the
576 // table completely filled with tombstones, no lookup would ever succeed,
577 // causing infinite loops in lookup.
578 unsigned NewNumEntries = getNumEntries() + 1;
579 unsigned NumBuckets = getNumBuckets();
580 if (LLVM_UNLIKELY(NewNumEntries * 4 >= NumBuckets * 3)__builtin_expect((bool)(NewNumEntries * 4 >= NumBuckets * 3
), false)) {
581 this->grow(NumBuckets * 2);
582 LookupBucketFor(Lookup, TheBucket);
583 NumBuckets = getNumBuckets();
584 } else if (LLVM_UNLIKELY(NumBuckets-(NewNumEntries+getNumTombstones()) <=__builtin_expect((bool)(NumBuckets-(NewNumEntries+getNumTombstones
()) <= NumBuckets/8), false)
585 NumBuckets/8)__builtin_expect((bool)(NumBuckets-(NewNumEntries+getNumTombstones
()) <= NumBuckets/8), false)) {
586 this->grow(NumBuckets);
587 LookupBucketFor(Lookup, TheBucket);
588 }
589 assert(TheBucket)((void)0);
590
591 // Only update the state after we've grown our bucket space appropriately
592 // so that when growing buckets we have self-consistent entry count.
593 incrementNumEntries();
594
595 // If we are writing over a tombstone, remember this.
596 const KeyT EmptyKey = getEmptyKey();
597 if (!KeyInfoT::isEqual(TheBucket->getFirst(), EmptyKey))
598 decrementNumTombstones();
599
600 return TheBucket;
601 }
602
603 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
604 /// FoundBucket. If the bucket contains the key and a value, this returns
605 /// true, otherwise it returns a bucket with an empty marker or tombstone and
606 /// returns false.
607 template<typename LookupKeyT>
608 bool LookupBucketFor(const LookupKeyT &Val,
609 const BucketT *&FoundBucket) const {
610 const BucketT *BucketsPtr = getBuckets();
611 const unsigned NumBuckets = getNumBuckets();
612
613 if (NumBuckets == 0) {
614 FoundBucket = nullptr;
615 return false;
616 }
617
618 // FoundTombstone - Keep track of whether we find a tombstone while probing.
619 const BucketT *FoundTombstone = nullptr;
620 const KeyT EmptyKey = getEmptyKey();
621 const KeyT TombstoneKey = getTombstoneKey();
622 assert(!KeyInfoT::isEqual(Val, EmptyKey) &&((void)0)
623 !KeyInfoT::isEqual(Val, TombstoneKey) &&((void)0)
624 "Empty/Tombstone value shouldn't be inserted into map!")((void)0);
625
626 unsigned BucketNo = getHashValue(Val) & (NumBuckets-1);
627 unsigned ProbeAmt = 1;
628 while (true) {
629 const BucketT *ThisBucket = BucketsPtr + BucketNo;
630 // Found Val's bucket? If so, return it.
631 if (LLVM_LIKELY(KeyInfoT::isEqual(Val, ThisBucket->getFirst()))__builtin_expect((bool)(KeyInfoT::isEqual(Val, ThisBucket->
getFirst())), true)) {
632 FoundBucket = ThisBucket;
633 return true;
634 }
635
636 // If we found an empty bucket, the key doesn't exist in the set.
637 // Insert it and return the default value.
638 if (LLVM_LIKELY(KeyInfoT::isEqual(ThisBucket->getFirst(), EmptyKey))__builtin_expect((bool)(KeyInfoT::isEqual(ThisBucket->getFirst
(), EmptyKey)), true)) {
639 // If we've already seen a tombstone while probing, fill it in instead
640 // of the empty bucket we eventually probed to.
641 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
642 return false;
643 }
644
645 // If this is a tombstone, remember it. If Val ends up not in the map, we
646 // prefer to return it than something that would require more probing.
647 if (KeyInfoT::isEqual(ThisBucket->getFirst(), TombstoneKey) &&
648 !FoundTombstone)
649 FoundTombstone = ThisBucket; // Remember the first tombstone found.
650
651 // Otherwise, it's a hash collision or a tombstone, continue quadratic
652 // probing.
653 BucketNo += ProbeAmt++;
654 BucketNo &= (NumBuckets-1);
655 }
656 }
657
658 template <typename LookupKeyT>
659 bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) {
660 const BucketT *ConstFoundBucket;
661 bool Result = const_cast<const DenseMapBase *>(this)
662 ->LookupBucketFor(Val, ConstFoundBucket);
663 FoundBucket = const_cast<BucketT *>(ConstFoundBucket);
664 return Result;
665 }
666
667public:
668 /// Return the approximate size (in bytes) of the actual map.
669 /// This is just the raw memory used by DenseMap.
670 /// If entries are pointers to objects, the size of the referenced objects
671 /// are not included.
672 size_t getMemorySize() const {
673 return getNumBuckets() * sizeof(BucketT);
674 }
675};
676
677/// Equality comparison for DenseMap.
678///
679/// Iterates over elements of LHS confirming that each (key, value) pair in LHS
680/// is also in RHS, and that no additional pairs are in RHS.
681/// Equivalent to N calls to RHS.find and N value comparisons. Amortized
682/// complexity is linear, worst case is O(N^2) (if every hash collides).
683template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
684 typename BucketT>
685bool operator==(
686 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &LHS,
687 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &RHS) {
688 if (LHS.size() != RHS.size())
689 return false;
690
691 for (auto &KV : LHS) {
692 auto I = RHS.find(KV.first);
693 if (I == RHS.end() || I->second != KV.second)
694 return false;
695 }
696
697 return true;
698}
699
700/// Inequality comparison for DenseMap.
701///
702/// Equivalent to !(LHS == RHS). See operator== for performance notes.
703template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
704 typename BucketT>
705bool operator!=(
706 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &LHS,
707 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &RHS) {
708 return !(LHS == RHS);
709}
710
711template <typename KeyT, typename ValueT,
712 typename KeyInfoT = DenseMapInfo<KeyT>,
713 typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
714class DenseMap : public DenseMapBase<DenseMap<KeyT, ValueT, KeyInfoT, BucketT>,
715 KeyT, ValueT, KeyInfoT, BucketT> {
716 friend class DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
717
718 // Lift some types from the dependent base class into this class for
719 // simplicity of referring to them.
720 using BaseT = DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
721
722 BucketT *Buckets;
723 unsigned NumEntries;
724 unsigned NumTombstones;
725 unsigned NumBuckets;
726
727public:
728 /// Create a DenseMap with an optional \p InitialReserve that guarantee that
729 /// this number of elements can be inserted in the map without grow()
730 explicit DenseMap(unsigned InitialReserve = 0) { init(InitialReserve); }
731
732 DenseMap(const DenseMap &other) : BaseT() {
733 init(0);
734 copyFrom(other);
735 }
736
737 DenseMap(DenseMap &&other) : BaseT() {
738 init(0);
739 swap(other);
740 }
741
742 template<typename InputIt>
743 DenseMap(const InputIt &I, const InputIt &E) {
744 init(std::distance(I, E));
745 this->insert(I, E);
746 }
747
748 DenseMap(std::initializer_list<typename BaseT::value_type> Vals) {
749 init(Vals.size());
750 this->insert(Vals.begin(), Vals.end());
751 }
752
753 ~DenseMap() {
754 this->destroyAll();
755 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
756 }
757
758 void swap(DenseMap& RHS) {
759 this->incrementEpoch();
760 RHS.incrementEpoch();
761 std::swap(Buckets, RHS.Buckets);
762 std::swap(NumEntries, RHS.NumEntries);
763 std::swap(NumTombstones, RHS.NumTombstones);
764 std::swap(NumBuckets, RHS.NumBuckets);
765 }
766
767 DenseMap& operator=(const DenseMap& other) {
768 if (&other != this)
769 copyFrom(other);
770 return *this;
771 }
772
773 DenseMap& operator=(DenseMap &&other) {
774 this->destroyAll();
775 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
776 init(0);
777 swap(other);
778 return *this;
779 }
780
781 void copyFrom(const DenseMap& other) {
782 this->destroyAll();
783 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
784 if (allocateBuckets(other.NumBuckets)) {
785 this->BaseT::copyFrom(other);
786 } else {
787 NumEntries = 0;
788 NumTombstones = 0;
789 }
790 }
791
792 void init(unsigned InitNumEntries) {
793 auto InitBuckets = BaseT::getMinBucketToReserveForEntries(InitNumEntries);
794 if (allocateBuckets(InitBuckets)) {
795 this->BaseT::initEmpty();
796 } else {
797 NumEntries = 0;
798 NumTombstones = 0;
799 }
800 }
801
802 void grow(unsigned AtLeast) {
803 unsigned OldNumBuckets = NumBuckets;
804 BucketT *OldBuckets = Buckets;
805
806 allocateBuckets(std::max<unsigned>(64, static_cast<unsigned>(NextPowerOf2(AtLeast-1))));
807 assert(Buckets)((void)0);
808 if (!OldBuckets) {
809 this->BaseT::initEmpty();
810 return;
811 }
812
813 this->moveFromOldBuckets(OldBuckets, OldBuckets+OldNumBuckets);
814
815 // Free the old table.
816 deallocate_buffer(OldBuckets, sizeof(BucketT) * OldNumBuckets,
817 alignof(BucketT));
818 }
819
820 void shrink_and_clear() {
821 unsigned OldNumBuckets = NumBuckets;
822 unsigned OldNumEntries = NumEntries;
823 this->destroyAll();
824
825 // Reduce the number of buckets.
826 unsigned NewNumBuckets = 0;
827 if (OldNumEntries)
828 NewNumBuckets = std::max(64, 1 << (Log2_32_Ceil(OldNumEntries) + 1));
829 if (NewNumBuckets == NumBuckets) {
830 this->BaseT::initEmpty();
831 return;
832 }
833
834 deallocate_buffer(Buckets, sizeof(BucketT) * OldNumBuckets,
835 alignof(BucketT));
836 init(NewNumBuckets);
837 }
838
839private:
840 unsigned getNumEntries() const {
841 return NumEntries;
842 }
843
844 void setNumEntries(unsigned Num) {
845 NumEntries = Num;
846 }
847
848 unsigned getNumTombstones() const {
849 return NumTombstones;
850 }
851
852 void setNumTombstones(unsigned Num) {
853 NumTombstones = Num;
854 }
855
856 BucketT *getBuckets() const {
857 return Buckets;
858 }
859
860 unsigned getNumBuckets() const {
861 return NumBuckets;
862 }
863
864 bool allocateBuckets(unsigned Num) {
865 NumBuckets = Num;
866 if (NumBuckets == 0) {
867 Buckets = nullptr;
868 return false;
869 }
870
871 Buckets = static_cast<BucketT *>(
872 allocate_buffer(sizeof(BucketT) * NumBuckets, alignof(BucketT)));
873 return true;
874 }
875};
876
877template <typename KeyT, typename ValueT, unsigned InlineBuckets = 4,
878 typename KeyInfoT = DenseMapInfo<KeyT>,
879 typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
880class SmallDenseMap
881 : public DenseMapBase<
882 SmallDenseMap<KeyT, ValueT, InlineBuckets, KeyInfoT, BucketT>, KeyT,
883 ValueT, KeyInfoT, BucketT> {
884 friend class DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
885
886 // Lift some types from the dependent base class into this class for
887 // simplicity of referring to them.
888 using BaseT = DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
889
890 static_assert(isPowerOf2_64(InlineBuckets),
891 "InlineBuckets must be a power of 2.");
892
893 unsigned Small : 1;
894 unsigned NumEntries : 31;
895 unsigned NumTombstones;
896
897 struct LargeRep {
898 BucketT *Buckets;
899 unsigned NumBuckets;
900 };
901
902 /// A "union" of an inline bucket array and the struct representing
903 /// a large bucket. This union will be discriminated by the 'Small' bit.
904 AlignedCharArrayUnion<BucketT[InlineBuckets], LargeRep> storage;
905
906public:
907 explicit SmallDenseMap(unsigned NumInitBuckets = 0) {
908 init(NumInitBuckets);
909 }
910
911 SmallDenseMap(const SmallDenseMap &other) : BaseT() {
912 init(0);
913 copyFrom(other);
914 }
915
916 SmallDenseMap(SmallDenseMap &&other) : BaseT() {
917 init(0);
918 swap(other);
919 }
920
921 template<typename InputIt>
922 SmallDenseMap(const InputIt &I, const InputIt &E) {
923 init(NextPowerOf2(std::distance(I, E)));
924 this->insert(I, E);
925 }
926
927 SmallDenseMap(std::initializer_list<typename BaseT::value_type> Vals)
928 : SmallDenseMap(Vals.begin(), Vals.end()) {}
929
930 ~SmallDenseMap() {
931 this->destroyAll();
932 deallocateBuckets();
933 }
934
935 void swap(SmallDenseMap& RHS) {
936 unsigned TmpNumEntries = RHS.NumEntries;
937 RHS.NumEntries = NumEntries;
938 NumEntries = TmpNumEntries;
939 std::swap(NumTombstones, RHS.NumTombstones);
940
941 const KeyT EmptyKey = this->getEmptyKey();
942 const KeyT TombstoneKey = this->getTombstoneKey();
943 if (Small && RHS.Small) {
944 // If we're swapping inline bucket arrays, we have to cope with some of
945 // the tricky bits of DenseMap's storage system: the buckets are not
946 // fully initialized. Thus we swap every key, but we may have
947 // a one-directional move of the value.
948 for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
949 BucketT *LHSB = &getInlineBuckets()[i],
950 *RHSB = &RHS.getInlineBuckets()[i];
951 bool hasLHSValue = (!KeyInfoT::isEqual(LHSB->getFirst(), EmptyKey) &&
952 !KeyInfoT::isEqual(LHSB->getFirst(), TombstoneKey));
953 bool hasRHSValue = (!KeyInfoT::isEqual(RHSB->getFirst(), EmptyKey) &&
954 !KeyInfoT::isEqual(RHSB->getFirst(), TombstoneKey));
955 if (hasLHSValue && hasRHSValue) {
956 // Swap together if we can...
957 std::swap(*LHSB, *RHSB);
958 continue;
959 }
960 // Swap separately and handle any asymmetry.
961 std::swap(LHSB->getFirst(), RHSB->getFirst());
962 if (hasLHSValue) {
963 ::new (&RHSB->getSecond()) ValueT(std::move(LHSB->getSecond()));
964 LHSB->getSecond().~ValueT();
965 } else if (hasRHSValue) {
966 ::new (&LHSB->getSecond()) ValueT(std::move(RHSB->getSecond()));
967 RHSB->getSecond().~ValueT();
968 }
969 }
970 return;
971 }
972 if (!Small && !RHS.Small) {
973 std::swap(getLargeRep()->Buckets, RHS.getLargeRep()->Buckets);
974 std::swap(getLargeRep()->NumBuckets, RHS.getLargeRep()->NumBuckets);
975 return;
976 }
977
978 SmallDenseMap &SmallSide = Small ? *this : RHS;
979 SmallDenseMap &LargeSide = Small ? RHS : *this;
980
981 // First stash the large side's rep and move the small side across.
982 LargeRep TmpRep = std::move(*LargeSide.getLargeRep());
983 LargeSide.getLargeRep()->~LargeRep();
984 LargeSide.Small = true;
985 // This is similar to the standard move-from-old-buckets, but the bucket
986 // count hasn't actually rotated in this case. So we have to carefully
987 // move construct the keys and values into their new locations, but there
988 // is no need to re-hash things.
989 for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
990 BucketT *NewB = &LargeSide.getInlineBuckets()[i],
991 *OldB = &SmallSide.getInlineBuckets()[i];
992 ::new (&NewB->getFirst()) KeyT(std::move(OldB->getFirst()));
993 OldB->getFirst().~KeyT();
994 if (!KeyInfoT::isEqual(NewB->getFirst(), EmptyKey) &&
995 !KeyInfoT::isEqual(NewB->getFirst(), TombstoneKey)) {
996 ::new (&NewB->getSecond()) ValueT(std::move(OldB->getSecond()));
997 OldB->getSecond().~ValueT();
998 }
999 }
1000
1001 // The hard part of moving the small buckets across is done, just move
1002 // the TmpRep into its new home.
1003 SmallSide.Small = false;
1004 new (SmallSide.getLargeRep()) LargeRep(std::move(TmpRep));
1005 }
1006
1007 SmallDenseMap& operator=(const SmallDenseMap& other) {
1008 if (&other != this)
1009 copyFrom(other);
1010 return *this;
1011 }
1012
1013 SmallDenseMap& operator=(SmallDenseMap &&other) {
1014 this->destroyAll();
1015 deallocateBuckets();
1016 init(0);
1017 swap(other);
1018 return *this;
1019 }
1020
1021 void copyFrom(const SmallDenseMap& other) {
1022 this->destroyAll();
1023 deallocateBuckets();
1024 Small = true;
1025 if (other.getNumBuckets() > InlineBuckets) {
1026 Small = false;
1027 new (getLargeRep()) LargeRep(allocateBuckets(other.getNumBuckets()));
1028 }
1029 this->BaseT::copyFrom(other);
1030 }
1031
1032 void init(unsigned InitBuckets) {
1033 Small = true;
1034 if (InitBuckets > InlineBuckets) {
1035 Small = false;
1036 new (getLargeRep()) LargeRep(allocateBuckets(InitBuckets));
1037 }
1038 this->BaseT::initEmpty();
1039 }
1040
1041 void grow(unsigned AtLeast) {
1042 if (AtLeast > InlineBuckets)
1043 AtLeast = std::max<unsigned>(64, NextPowerOf2(AtLeast-1));
1044
1045 if (Small) {
1046 // First move the inline buckets into a temporary storage.
1047 AlignedCharArrayUnion<BucketT[InlineBuckets]> TmpStorage;
1048 BucketT *TmpBegin = reinterpret_cast<BucketT *>(&TmpStorage);
1049 BucketT *TmpEnd = TmpBegin;
1050
1051 // Loop over the buckets, moving non-empty, non-tombstones into the
1052 // temporary storage. Have the loop move the TmpEnd forward as it goes.
1053 const KeyT EmptyKey = this->getEmptyKey();
1054 const KeyT TombstoneKey = this->getTombstoneKey();
1055 for (BucketT *P = getBuckets(), *E = P + InlineBuckets; P != E; ++P) {
1056 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
1057 !KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
1058 assert(size_t(TmpEnd - TmpBegin) < InlineBuckets &&((void)0)
1059 "Too many inline buckets!")((void)0);
1060 ::new (&TmpEnd->getFirst()) KeyT(std::move(P->getFirst()));
1061 ::new (&TmpEnd->getSecond()) ValueT(std::move(P->getSecond()));
1062 ++TmpEnd;
1063 P->getSecond().~ValueT();
1064 }
1065 P->getFirst().~KeyT();
1066 }
1067
1068 // AtLeast == InlineBuckets can happen if there are many tombstones,
1069 // and grow() is used to remove them. Usually we always switch to the
1070 // large rep here.
1071 if (AtLeast > InlineBuckets) {
1072 Small = false;
1073 new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
1074 }
1075 this->moveFromOldBuckets(TmpBegin, TmpEnd);
1076 return;
1077 }
1078
1079 LargeRep OldRep = std::move(*getLargeRep());
1080 getLargeRep()->~LargeRep();
1081 if (AtLeast <= InlineBuckets) {
1082 Small = true;
1083 } else {
1084 new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
1085 }
1086
1087 this->moveFromOldBuckets(OldRep.Buckets, OldRep.Buckets+OldRep.NumBuckets);
1088
1089 // Free the old table.
1090 deallocate_buffer(OldRep.Buckets, sizeof(BucketT) * OldRep.NumBuckets,
1091 alignof(BucketT));
1092 }
1093
1094 void shrink_and_clear() {
1095 unsigned OldSize = this->size();
1096 this->destroyAll();
1097
1098 // Reduce the number of buckets.
1099 unsigned NewNumBuckets = 0;
1100 if (OldSize) {
1101 NewNumBuckets = 1 << (Log2_32_Ceil(OldSize) + 1);
1102 if (NewNumBuckets > InlineBuckets && NewNumBuckets < 64u)
1103 NewNumBuckets = 64;
1104 }
1105 if ((Small && NewNumBuckets <= InlineBuckets) ||
1106 (!Small && NewNumBuckets == getLargeRep()->NumBuckets)) {
1107 this->BaseT::initEmpty();
1108 return;
1109 }
1110
1111 deallocateBuckets();
1112 init(NewNumBuckets);
1113 }
1114
1115private:
1116 unsigned getNumEntries() const {
1117 return NumEntries;
1118 }
1119
1120 void setNumEntries(unsigned Num) {
1121 // NumEntries is hardcoded to be 31 bits wide.
1122 assert(Num < (1U << 31) && "Cannot support more than 1<<31 entries")((void)0);
1123 NumEntries = Num;
1124 }
1125
1126 unsigned getNumTombstones() const {
1127 return NumTombstones;
1128 }
1129
1130 void setNumTombstones(unsigned Num) {
1131 NumTombstones = Num;
1132 }
1133
1134 const BucketT *getInlineBuckets() const {
1135 assert(Small)((void)0);
1136 // Note that this cast does not violate aliasing rules as we assert that
1137 // the memory's dynamic type is the small, inline bucket buffer, and the
1138 // 'storage' is a POD containing a char buffer.
1139 return reinterpret_cast<const BucketT *>(&storage);
1140 }
1141
1142 BucketT *getInlineBuckets() {
1143 return const_cast<BucketT *>(
1144 const_cast<const SmallDenseMap *>(this)->getInlineBuckets());
1145 }
1146
1147 const LargeRep *getLargeRep() const {
1148 assert(!Small)((void)0);
1149 // Note, same rule about aliasing as with getInlineBuckets.
1150 return reinterpret_cast<const LargeRep *>(&storage);
1151 }
1152
1153 LargeRep *getLargeRep() {
1154 return const_cast<LargeRep *>(
1155 const_cast<const SmallDenseMap *>(this)->getLargeRep());
1156 }
1157
1158 const BucketT *getBuckets() const {
1159 return Small ? getInlineBuckets() : getLargeRep()->Buckets;
1160 }
1161
1162 BucketT *getBuckets() {
1163 return const_cast<BucketT *>(
1164 const_cast<const SmallDenseMap *>(this)->getBuckets());
1165 }
1166
1167 unsigned getNumBuckets() const {
1168 return Small ? InlineBuckets : getLargeRep()->NumBuckets;
1169 }
1170
1171 void deallocateBuckets() {
1172 if (Small)
1173 return;
1174
1175 deallocate_buffer(getLargeRep()->Buckets,
1176 sizeof(BucketT) * getLargeRep()->NumBuckets,
1177 alignof(BucketT));
1178 getLargeRep()->~LargeRep();
1179 }
1180
1181 LargeRep allocateBuckets(unsigned Num) {
1182 assert(Num > InlineBuckets && "Must allocate more buckets than are inline")((void)0);
1183 LargeRep Rep = {static_cast<BucketT *>(allocate_buffer(
1184 sizeof(BucketT) * Num, alignof(BucketT))),
1185 Num};
1186 return Rep;
1187 }
1188};
1189
1190template <typename KeyT, typename ValueT, typename KeyInfoT, typename Bucket,
1191 bool IsConst>
1192class DenseMapIterator : DebugEpochBase::HandleBase {
1193 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>;
1194 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, false>;
1195
1196public:
1197 using difference_type = ptrdiff_t;
1198 using value_type =
1199 typename std::conditional<IsConst, const Bucket, Bucket>::type;
1200 using pointer = value_type *;
1201 using reference = value_type &;
1202 using iterator_category = std::forward_iterator_tag;
1203
1204private:
1205 pointer Ptr = nullptr;
1206 pointer End = nullptr;
1207
1208public:
1209 DenseMapIterator() = default;
1210
1211 DenseMapIterator(pointer Pos, pointer E, const DebugEpochBase &Epoch,
1212 bool NoAdvance = false)
1213 : DebugEpochBase::HandleBase(&Epoch), Ptr(Pos), End(E) {
1214 assert(isHandleInSync() && "invalid construction!")((void)0);
1215
1216 if (NoAdvance) return;
1217 if (shouldReverseIterate<KeyT>()) {
1218 RetreatPastEmptyBuckets();
1219 return;
1220 }
1221 AdvancePastEmptyBuckets();
1222 }
1223
1224 // Converting ctor from non-const iterators to const iterators. SFINAE'd out
1225 // for const iterator destinations so it doesn't end up as a user defined copy
1226 // constructor.
1227 template <bool IsConstSrc,
1228 typename = std::enable_if_t<!IsConstSrc && IsConst>>
1229 DenseMapIterator(
1230 const DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, IsConstSrc> &I)
1231 : DebugEpochBase::HandleBase(I), Ptr(I.Ptr), End(I.End) {}
1232
1233 reference operator*() const {
1234 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1235 assert(Ptr != End && "dereferencing end() iterator")((void)0);
1236 if (shouldReverseIterate<KeyT>())
1237 return Ptr[-1];
1238 return *Ptr;
1239 }
1240 pointer operator->() const {
1241 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1242 assert(Ptr != End && "dereferencing end() iterator")((void)0);
1243 if (shouldReverseIterate<KeyT>())
1244 return &(Ptr[-1]);
1245 return Ptr;
1246 }
1247
1248 friend bool operator==(const DenseMapIterator &LHS,
1249 const DenseMapIterator &RHS) {
1250 assert((!LHS.Ptr || LHS.isHandleInSync()) && "handle not in sync!")((void)0);
1251 assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!")((void)0);
1252 assert(LHS.getEpochAddress() == RHS.getEpochAddress() &&((void)0)
1253 "comparing incomparable iterators!")((void)0);
1254 return LHS.Ptr == RHS.Ptr;
25
←
Assuming 'LHS.Ptr' is not equal to 'RHS.Ptr'
→
26
←
Returning zero, which participates in a condition later
→
1255 }
1256
1257 friend bool operator!=(const DenseMapIterator &LHS,
1258 const DenseMapIterator &RHS) {
1259 return !(LHS == RHS);
24
←
Calling 'operator=='
→
27
←
Returning from 'operator=='
→
28
←
Returning the value 1, which participates in a condition later
→
1260 }
1261
1262 inline DenseMapIterator& operator++() { // Preincrement
1263 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1264 assert(Ptr != End && "incrementing end() iterator")((void)0);
1265 if (shouldReverseIterate<KeyT>()) {
1266 --Ptr;
1267 RetreatPastEmptyBuckets();
1268 return *this;
1269 }
1270 ++Ptr;
1271 AdvancePastEmptyBuckets();
1272 return *this;
1273 }
1274 DenseMapIterator operator++(int) { // Postincrement
1275 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1276 DenseMapIterator tmp = *this; ++*this; return tmp;
1277 }
1278
1279private:
1280 void AdvancePastEmptyBuckets() {
1281 assert(Ptr <= End)((void)0);
1282 const KeyT Empty = KeyInfoT::getEmptyKey();
1283 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1284
1285 while (Ptr != End && (KeyInfoT::isEqual(Ptr->getFirst(), Empty) ||
1286 KeyInfoT::isEqual(Ptr->getFirst(), Tombstone)))
1287 ++Ptr;
1288 }
1289
1290 void RetreatPastEmptyBuckets() {
1291 assert(Ptr >= End)((void)0);
1292 const KeyT Empty = KeyInfoT::getEmptyKey();
1293 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1294
1295 while (Ptr != End && (KeyInfoT::isEqual(Ptr[-1].getFirst(), Empty) ||
1296 KeyInfoT::isEqual(Ptr[-1].getFirst(), Tombstone)))
1297 --Ptr;
1298 }
1299};
1300
1301template <typename KeyT, typename ValueT, typename KeyInfoT>
1302inline size_t capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) {
1303 return X.getMemorySize();
1304}
1305
1306} // end namespace llvm
1307
1308#endif // LLVM_ADT_DENSEMAP_H