LLVM 19.0.0git
ArgumentPromotion.cpp
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1//===- ArgumentPromotion.cpp - Promote by-reference arguments -------------===//
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 pass promotes "by reference" arguments to be "by value" arguments. In
10// practice, this means looking for internal functions that have pointer
11// arguments. If it can prove, through the use of alias analysis, that an
12// argument is *only* loaded, then it can pass the value into the function
13// instead of the address of the value. This can cause recursive simplification
14// of code and lead to the elimination of allocas (especially in C++ template
15// code like the STL).
16//
17// This pass also handles aggregate arguments that are passed into a function,
18// scalarizing them if the elements of the aggregate are only loaded. Note that
19// by default it refuses to scalarize aggregates which would require passing in
20// more than three operands to the function, because passing thousands of
21// operands for a large array or structure is unprofitable! This limit can be
22// configured or disabled, however.
23//
24// Note that this transformation could also be done for arguments that are only
25// stored to (returning the value instead), but does not currently. This case
26// would be best handled when and if LLVM begins supporting multiple return
27// values from functions.
28//
29//===----------------------------------------------------------------------===//
30
32
34#include "llvm/ADT/STLExtras.h"
35#include "llvm/ADT/ScopeExit.h"
38#include "llvm/ADT/Statistic.h"
39#include "llvm/ADT/Twine.h"
43#include "llvm/Analysis/Loads.h"
47#include "llvm/IR/Argument.h"
48#include "llvm/IR/Attributes.h"
49#include "llvm/IR/BasicBlock.h"
50#include "llvm/IR/CFG.h"
51#include "llvm/IR/Constants.h"
52#include "llvm/IR/DataLayout.h"
54#include "llvm/IR/Dominators.h"
55#include "llvm/IR/Function.h"
56#include "llvm/IR/IRBuilder.h"
57#include "llvm/IR/InstrTypes.h"
58#include "llvm/IR/Instruction.h"
60#include "llvm/IR/Metadata.h"
61#include "llvm/IR/NoFolder.h"
62#include "llvm/IR/PassManager.h"
63#include "llvm/IR/Type.h"
64#include "llvm/IR/Use.h"
65#include "llvm/IR/User.h"
66#include "llvm/IR/Value.h"
68#include "llvm/Support/Debug.h"
72#include <algorithm>
73#include <cassert>
74#include <cstdint>
75#include <utility>
76#include <vector>
77
78using namespace llvm;
79
80#define DEBUG_TYPE "argpromotion"
81
82STATISTIC(NumArgumentsPromoted, "Number of pointer arguments promoted");
83STATISTIC(NumArgumentsDead, "Number of dead pointer args eliminated");
84
85namespace {
86
87struct ArgPart {
88 Type *Ty;
89 Align Alignment;
90 /// A representative guaranteed-executed load or store instruction for use by
91 /// metadata transfer.
92 Instruction *MustExecInstr;
93};
94
95using OffsetAndArgPart = std::pair<int64_t, ArgPart>;
96
97} // end anonymous namespace
98
100 Value *Ptr, Type *ResElemTy, int64_t Offset) {
101 if (Offset != 0) {
102 APInt APOffset(DL.getIndexTypeSizeInBits(Ptr->getType()), Offset);
103 Ptr = IRB.CreatePtrAdd(Ptr, IRB.getInt(APOffset));
104 }
105 return Ptr;
106}
107
108/// DoPromotion - This method actually performs the promotion of the specified
109/// arguments, and returns the new function. At this point, we know that it's
110/// safe to do so.
111static Function *
114 &ArgsToPromote) {
115 // Start by computing a new prototype for the function, which is the same as
116 // the old function, but has modified arguments.
117 FunctionType *FTy = F->getFunctionType();
118 std::vector<Type *> Params;
119
120 // Attribute - Keep track of the parameter attributes for the arguments
121 // that we are *not* promoting. For the ones that we do promote, the parameter
122 // attributes are lost
124 // Mapping from old to new argument indices. -1 for promoted or removed
125 // arguments.
126 SmallVector<unsigned> NewArgIndices;
127 AttributeList PAL = F->getAttributes();
128
129 // First, determine the new argument list
130 unsigned ArgNo = 0, NewArgNo = 0;
131 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
132 ++I, ++ArgNo) {
133 if (!ArgsToPromote.count(&*I)) {
134 // Unchanged argument
135 Params.push_back(I->getType());
136 ArgAttrVec.push_back(PAL.getParamAttrs(ArgNo));
137 NewArgIndices.push_back(NewArgNo++);
138 } else if (I->use_empty()) {
139 // Dead argument (which are always marked as promotable)
140 ++NumArgumentsDead;
141 NewArgIndices.push_back((unsigned)-1);
142 } else {
143 const auto &ArgParts = ArgsToPromote.find(&*I)->second;
144 for (const auto &Pair : ArgParts) {
145 Params.push_back(Pair.second.Ty);
146 ArgAttrVec.push_back(AttributeSet());
147 }
148 ++NumArgumentsPromoted;
149 NewArgIndices.push_back((unsigned)-1);
150 NewArgNo += ArgParts.size();
151 }
152 }
153
154 Type *RetTy = FTy->getReturnType();
155
156 // Construct the new function type using the new arguments.
157 FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg());
158
159 // Create the new function body and insert it into the module.
160 Function *NF = Function::Create(NFTy, F->getLinkage(), F->getAddressSpace(),
161 F->getName());
163 NF->copyMetadata(F, 0);
164 NF->setIsNewDbgInfoFormat(F->IsNewDbgInfoFormat);
165
166 // The new function will have the !dbg metadata copied from the original
167 // function. The original function may not be deleted, and dbg metadata need
168 // to be unique, so we need to drop it.
169 F->setSubprogram(nullptr);
170
171 LLVM_DEBUG(dbgs() << "ARG PROMOTION: Promoting to:" << *NF << "\n"
172 << "From: " << *F);
173
174 uint64_t LargestVectorWidth = 0;
175 for (auto *I : Params)
176 if (auto *VT = dyn_cast<llvm::VectorType>(I))
177 LargestVectorWidth = std::max(
178 LargestVectorWidth, VT->getPrimitiveSizeInBits().getKnownMinValue());
179
180 // Recompute the parameter attributes list based on the new arguments for
181 // the function.
182 NF->setAttributes(AttributeList::get(F->getContext(), PAL.getFnAttrs(),
183 PAL.getRetAttrs(), ArgAttrVec));
184
185 // Remap argument indices in allocsize attribute.
186 if (auto AllocSize = NF->getAttributes().getFnAttrs().getAllocSizeArgs()) {
187 unsigned Arg1 = NewArgIndices[AllocSize->first];
188 assert(Arg1 != (unsigned)-1 && "allocsize cannot be promoted argument");
189 std::optional<unsigned> Arg2;
190 if (AllocSize->second) {
191 Arg2 = NewArgIndices[*AllocSize->second];
192 assert(Arg2 != (unsigned)-1 && "allocsize cannot be promoted argument");
193 }
194 NF->addFnAttr(Attribute::getWithAllocSizeArgs(F->getContext(), Arg1, Arg2));
195 }
196
197 AttributeFuncs::updateMinLegalVectorWidthAttr(*NF, LargestVectorWidth);
198 ArgAttrVec.clear();
199
200 F->getParent()->getFunctionList().insert(F->getIterator(), NF);
201 NF->takeName(F);
202
203 // Loop over all the callers of the function, transforming the call sites to
204 // pass in the loaded pointers.
206 const DataLayout &DL = F->getParent()->getDataLayout();
208
209 while (!F->use_empty()) {
210 CallBase &CB = cast<CallBase>(*F->user_back());
211 assert(CB.getCalledFunction() == F);
212 const AttributeList &CallPAL = CB.getAttributes();
213 IRBuilder<NoFolder> IRB(&CB);
214
215 // Loop over the operands, inserting GEP and loads in the caller as
216 // appropriate.
217 auto *AI = CB.arg_begin();
218 ArgNo = 0;
219 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
220 ++I, ++AI, ++ArgNo) {
221 if (!ArgsToPromote.count(&*I)) {
222 Args.push_back(*AI); // Unmodified argument
223 ArgAttrVec.push_back(CallPAL.getParamAttrs(ArgNo));
224 } else if (!I->use_empty()) {
225 Value *V = *AI;
226 const auto &ArgParts = ArgsToPromote.find(&*I)->second;
227 for (const auto &Pair : ArgParts) {
228 LoadInst *LI = IRB.CreateAlignedLoad(
229 Pair.second.Ty,
230 createByteGEP(IRB, DL, V, Pair.second.Ty, Pair.first),
231 Pair.second.Alignment, V->getName() + ".val");
232 if (Pair.second.MustExecInstr) {
233 LI->setAAMetadata(Pair.second.MustExecInstr->getAAMetadata());
234 LI->copyMetadata(*Pair.second.MustExecInstr,
235 {LLVMContext::MD_dereferenceable,
236 LLVMContext::MD_dereferenceable_or_null,
237 LLVMContext::MD_noundef,
238 LLVMContext::MD_nontemporal});
239 // Only transfer poison-generating metadata if we also have
240 // !noundef.
241 // TODO: Without !noundef, we could merge this metadata across
242 // all promoted loads.
243 if (LI->hasMetadata(LLVMContext::MD_noundef))
244 LI->copyMetadata(*Pair.second.MustExecInstr,
245 {LLVMContext::MD_range, LLVMContext::MD_nonnull,
246 LLVMContext::MD_align});
247 }
248 Args.push_back(LI);
249 ArgAttrVec.push_back(AttributeSet());
250 }
251 } else {
252 assert(ArgsToPromote.count(&*I) && I->use_empty());
253 DeadArgs.emplace_back(AI->get());
254 }
255 }
256
257 // Push any varargs arguments on the list.
258 for (; AI != CB.arg_end(); ++AI, ++ArgNo) {
259 Args.push_back(*AI);
260 ArgAttrVec.push_back(CallPAL.getParamAttrs(ArgNo));
261 }
262
264 CB.getOperandBundlesAsDefs(OpBundles);
265
266 CallBase *NewCS = nullptr;
267 if (InvokeInst *II = dyn_cast<InvokeInst>(&CB)) {
268 NewCS = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(),
269 Args, OpBundles, "", CB.getIterator());
270 } else {
271 auto *NewCall =
272 CallInst::Create(NF, Args, OpBundles, "", CB.getIterator());
273 NewCall->setTailCallKind(cast<CallInst>(&CB)->getTailCallKind());
274 NewCS = NewCall;
275 }
276 NewCS->setCallingConv(CB.getCallingConv());
277 NewCS->setAttributes(AttributeList::get(F->getContext(),
278 CallPAL.getFnAttrs(),
279 CallPAL.getRetAttrs(), ArgAttrVec));
280 NewCS->copyMetadata(CB, {LLVMContext::MD_prof, LLVMContext::MD_dbg});
281 Args.clear();
282 ArgAttrVec.clear();
283
285 LargestVectorWidth);
286
287 if (!CB.use_empty()) {
288 CB.replaceAllUsesWith(NewCS);
289 NewCS->takeName(&CB);
290 }
291
292 // Finally, remove the old call from the program, reducing the use-count of
293 // F.
294 CB.eraseFromParent();
295 }
296
298
299 // Since we have now created the new function, splice the body of the old
300 // function right into the new function, leaving the old rotting hulk of the
301 // function empty.
302 NF->splice(NF->begin(), F);
303
304 // We will collect all the new created allocas to promote them into registers
305 // after the following loop
307
308 // Loop over the argument list, transferring uses of the old arguments over to
309 // the new arguments, also transferring over the names as well.
311 for (Argument &Arg : F->args()) {
312 if (!ArgsToPromote.count(&Arg)) {
313 // If this is an unmodified argument, move the name and users over to the
314 // new version.
315 Arg.replaceAllUsesWith(&*I2);
316 I2->takeName(&Arg);
317 ++I2;
318 continue;
319 }
320
321 // There potentially are metadata uses for things like llvm.dbg.value.
322 // Replace them with undef, after handling the other regular uses.
323 auto RauwUndefMetadata = make_scope_exit(
324 [&]() { Arg.replaceAllUsesWith(UndefValue::get(Arg.getType())); });
325
326 if (Arg.use_empty())
327 continue;
328
329 // Otherwise, if we promoted this argument, we have to create an alloca in
330 // the callee for every promotable part and store each of the new incoming
331 // arguments into the corresponding alloca, what lets the old code (the
332 // store instructions if they are allowed especially) a chance to work as
333 // before.
334 assert(Arg.getType()->isPointerTy() &&
335 "Only arguments with a pointer type are promotable");
336
337 IRBuilder<NoFolder> IRB(&NF->begin()->front());
338
339 // Add only the promoted elements, so parts from ArgsToPromote
341 for (const auto &Pair : ArgsToPromote.find(&Arg)->second) {
342 int64_t Offset = Pair.first;
343 const ArgPart &Part = Pair.second;
344
345 Argument *NewArg = I2++;
346 NewArg->setName(Arg.getName() + "." + Twine(Offset) + ".val");
347
348 AllocaInst *NewAlloca = IRB.CreateAlloca(
349 Part.Ty, nullptr, Arg.getName() + "." + Twine(Offset) + ".allc");
350 NewAlloca->setAlignment(Pair.second.Alignment);
351 IRB.CreateAlignedStore(NewArg, NewAlloca, Pair.second.Alignment);
352
353 // Collect the alloca to retarget the users to
354 OffsetToAlloca.insert({Offset, NewAlloca});
355 }
356
357 auto GetAlloca = [&](Value *Ptr) {
358 APInt Offset(DL.getIndexTypeSizeInBits(Ptr->getType()), 0);
359 Ptr = Ptr->stripAndAccumulateConstantOffsets(DL, Offset,
360 /* AllowNonInbounds */ true);
361 assert(Ptr == &Arg && "Not constant offset from arg?");
362 return OffsetToAlloca.lookup(Offset.getSExtValue());
363 };
364
365 // Cleanup the code from the dead instructions: GEPs and BitCasts in between
366 // the original argument and its users: loads and stores. Retarget every
367 // user to the new created alloca.
370 append_range(Worklist, Arg.users());
371 while (!Worklist.empty()) {
372 Value *V = Worklist.pop_back_val();
373 if (isa<BitCastInst>(V) || isa<GetElementPtrInst>(V)) {
374 DeadInsts.push_back(cast<Instruction>(V));
375 append_range(Worklist, V->users());
376 continue;
377 }
378
379 if (auto *LI = dyn_cast<LoadInst>(V)) {
380 Value *Ptr = LI->getPointerOperand();
381 LI->setOperand(LoadInst::getPointerOperandIndex(), GetAlloca(Ptr));
382 continue;
383 }
384
385 if (auto *SI = dyn_cast<StoreInst>(V)) {
386 assert(!SI->isVolatile() && "Volatile operations can't be promoted.");
387 Value *Ptr = SI->getPointerOperand();
388 SI->setOperand(StoreInst::getPointerOperandIndex(), GetAlloca(Ptr));
389 continue;
390 }
391
392 llvm_unreachable("Unexpected user");
393 }
394
395 for (Instruction *I : DeadInsts) {
396 I->replaceAllUsesWith(PoisonValue::get(I->getType()));
397 I->eraseFromParent();
398 }
399
400 // Collect the allocas for promotion
401 for (const auto &Pair : OffsetToAlloca) {
402 assert(isAllocaPromotable(Pair.second) &&
403 "By design, only promotable allocas should be produced.");
404 Allocas.push_back(Pair.second);
405 }
406 }
407
408 LLVM_DEBUG(dbgs() << "ARG PROMOTION: " << Allocas.size()
409 << " alloca(s) are promotable by Mem2Reg\n");
410
411 if (!Allocas.empty()) {
412 // And we are able to call the `promoteMemoryToRegister()` function.
413 // Our earlier checks have ensured that PromoteMemToReg() will
414 // succeed.
415 auto &DT = FAM.getResult<DominatorTreeAnalysis>(*NF);
416 auto &AC = FAM.getResult<AssumptionAnalysis>(*NF);
417 PromoteMemToReg(Allocas, DT, &AC);
418 }
419
420 return NF;
421}
422
423/// Return true if we can prove that all callees pass in a valid pointer for the
424/// specified function argument.
426 Align NeededAlign,
427 uint64_t NeededDerefBytes) {
428 Function *Callee = Arg->getParent();
429 const DataLayout &DL = Callee->getParent()->getDataLayout();
430 APInt Bytes(64, NeededDerefBytes);
431
432 // Check if the argument itself is marked dereferenceable and aligned.
433 if (isDereferenceableAndAlignedPointer(Arg, NeededAlign, Bytes, DL))
434 return true;
435
436 // Look at all call sites of the function. At this point we know we only have
437 // direct callees.
438 return all_of(Callee->users(), [&](User *U) {
439 CallBase &CB = cast<CallBase>(*U);
440 return isDereferenceableAndAlignedPointer(CB.getArgOperand(Arg->getArgNo()),
441 NeededAlign, Bytes, DL);
442 });
443}
444
445/// Determine that this argument is safe to promote, and find the argument
446/// parts it can be promoted into.
447static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR,
448 unsigned MaxElements, bool IsRecursive,
450 // Quick exit for unused arguments
451 if (Arg->use_empty())
452 return true;
453
454 // We can only promote this argument if all the uses are loads at known
455 // offsets.
456 //
457 // Promoting the argument causes it to be loaded in the caller
458 // unconditionally. This is only safe if we can prove that either the load
459 // would have happened in the callee anyway (ie, there is a load in the entry
460 // block) or the pointer passed in at every call site is guaranteed to be
461 // valid.
462 // In the former case, invalid loads can happen, but would have happened
463 // anyway, in the latter case, invalid loads won't happen. This prevents us
464 // from introducing an invalid load that wouldn't have happened in the
465 // original code.
466
468 Align NeededAlign(1);
469 uint64_t NeededDerefBytes = 0;
470
471 // And if this is a byval argument we also allow to have store instructions.
472 // Only handle in such way arguments with specified alignment;
473 // if it's unspecified, the actual alignment of the argument is
474 // target-specific.
475 bool AreStoresAllowed = Arg->getParamByValType() && Arg->getParamAlign();
476
477 // An end user of a pointer argument is a load or store instruction.
478 // Returns std::nullopt if this load or store is not based on the argument.
479 // Return true if we can promote the instruction, false otherwise.
480 auto HandleEndUser = [&](auto *I, Type *Ty,
481 bool GuaranteedToExecute) -> std::optional<bool> {
482 // Don't promote volatile or atomic instructions.
483 if (!I->isSimple())
484 return false;
485
486 Value *Ptr = I->getPointerOperand();
487 APInt Offset(DL.getIndexTypeSizeInBits(Ptr->getType()), 0);
488 Ptr = Ptr->stripAndAccumulateConstantOffsets(DL, Offset,
489 /* AllowNonInbounds */ true);
490 if (Ptr != Arg)
491 return std::nullopt;
492
493 if (Offset.getSignificantBits() >= 64)
494 return false;
495
496 TypeSize Size = DL.getTypeStoreSize(Ty);
497 // Don't try to promote scalable types.
498 if (Size.isScalable())
499 return false;
500
501 // If this is a recursive function and one of the types is a pointer,
502 // then promoting it might lead to recursive promotion.
503 if (IsRecursive && Ty->isPointerTy())
504 return false;
505
506 int64_t Off = Offset.getSExtValue();
507 auto Pair = ArgParts.try_emplace(
508 Off, ArgPart{Ty, I->getAlign(), GuaranteedToExecute ? I : nullptr});
509 ArgPart &Part = Pair.first->second;
510 bool OffsetNotSeenBefore = Pair.second;
511
512 // We limit promotion to only promoting up to a fixed number of elements of
513 // the aggregate.
514 if (MaxElements > 0 && ArgParts.size() > MaxElements) {
515 LLVM_DEBUG(dbgs() << "ArgPromotion of " << *Arg << " failed: "
516 << "more than " << MaxElements << " parts\n");
517 return false;
518 }
519
520 // For now, we only support loading/storing one specific type at a given
521 // offset.
522 if (Part.Ty != Ty) {
523 LLVM_DEBUG(dbgs() << "ArgPromotion of " << *Arg << " failed: "
524 << "accessed as both " << *Part.Ty << " and " << *Ty
525 << " at offset " << Off << "\n");
526 return false;
527 }
528
529 // If this instruction is not guaranteed to execute, and we haven't seen a
530 // load or store at this offset before (or it had lower alignment), then we
531 // need to remember that requirement.
532 // Note that skipping instructions of previously seen offsets is only
533 // correct because we only allow a single type for a given offset, which
534 // also means that the number of accessed bytes will be the same.
535 if (!GuaranteedToExecute &&
536 (OffsetNotSeenBefore || Part.Alignment < I->getAlign())) {
537 // We won't be able to prove dereferenceability for negative offsets.
538 if (Off < 0)
539 return false;
540
541 // If the offset is not aligned, an aligned base pointer won't help.
542 if (!isAligned(I->getAlign(), Off))
543 return false;
544
545 NeededDerefBytes = std::max(NeededDerefBytes, Off + Size.getFixedValue());
546 NeededAlign = std::max(NeededAlign, I->getAlign());
547 }
548
549 Part.Alignment = std::max(Part.Alignment, I->getAlign());
550 return true;
551 };
552
553 // Look for loads and stores that are guaranteed to execute on entry.
554 for (Instruction &I : Arg->getParent()->getEntryBlock()) {
555 std::optional<bool> Res{};
556 if (LoadInst *LI = dyn_cast<LoadInst>(&I))
557 Res = HandleEndUser(LI, LI->getType(), /* GuaranteedToExecute */ true);
558 else if (StoreInst *SI = dyn_cast<StoreInst>(&I))
559 Res = HandleEndUser(SI, SI->getValueOperand()->getType(),
560 /* GuaranteedToExecute */ true);
561 if (Res && !*Res)
562 return false;
563
565 break;
566 }
567
568 // Now look at all loads of the argument. Remember the load instructions
569 // for the aliasing check below.
573 auto AppendUses = [&](const Value *V) {
574 for (const Use &U : V->uses())
575 if (Visited.insert(&U).second)
576 Worklist.push_back(&U);
577 };
578 AppendUses(Arg);
579 while (!Worklist.empty()) {
580 const Use *U = Worklist.pop_back_val();
581 Value *V = U->getUser();
582 if (isa<BitCastInst>(V)) {
583 AppendUses(V);
584 continue;
585 }
586
587 if (auto *GEP = dyn_cast<GetElementPtrInst>(V)) {
588 if (!GEP->hasAllConstantIndices())
589 return false;
590 AppendUses(V);
591 continue;
592 }
593
594 if (auto *LI = dyn_cast<LoadInst>(V)) {
595 if (!*HandleEndUser(LI, LI->getType(), /* GuaranteedToExecute */ false))
596 return false;
597 Loads.push_back(LI);
598 continue;
599 }
600
601 // Stores are allowed for byval arguments
602 auto *SI = dyn_cast<StoreInst>(V);
603 if (AreStoresAllowed && SI &&
604 U->getOperandNo() == StoreInst::getPointerOperandIndex()) {
605 if (!*HandleEndUser(SI, SI->getValueOperand()->getType(),
606 /* GuaranteedToExecute */ false))
607 return false;
608 continue;
609 // Only stores TO the argument is allowed, all the other stores are
610 // unknown users
611 }
612
613 // Unknown user.
614 LLVM_DEBUG(dbgs() << "ArgPromotion of " << *Arg << " failed: "
615 << "unknown user " << *V << "\n");
616 return false;
617 }
618
619 if (NeededDerefBytes || NeededAlign > 1) {
620 // Try to prove a required deref / aligned requirement.
621 if (!allCallersPassValidPointerForArgument(Arg, NeededAlign,
622 NeededDerefBytes)) {
623 LLVM_DEBUG(dbgs() << "ArgPromotion of " << *Arg << " failed: "
624 << "not dereferenceable or aligned\n");
625 return false;
626 }
627 }
628
629 if (ArgParts.empty())
630 return true; // No users, this is a dead argument.
631
632 // Sort parts by offset.
633 append_range(ArgPartsVec, ArgParts);
634 sort(ArgPartsVec, llvm::less_first());
635
636 // Make sure the parts are non-overlapping.
637 int64_t Offset = ArgPartsVec[0].first;
638 for (const auto &Pair : ArgPartsVec) {
639 if (Pair.first < Offset)
640 return false; // Overlap with previous part.
641
642 Offset = Pair.first + DL.getTypeStoreSize(Pair.second.Ty);
643 }
644
645 // If store instructions are allowed, the path from the entry of the function
646 // to each load may be not free of instructions that potentially invalidate
647 // the load, and this is an admissible situation.
648 if (AreStoresAllowed)
649 return true;
650
651 // Okay, now we know that the argument is only used by load instructions, and
652 // it is safe to unconditionally perform all of them. Use alias analysis to
653 // check to see if the pointer is guaranteed to not be modified from entry of
654 // the function to each of the load instructions.
655
656 for (LoadInst *Load : Loads) {
657 // Check to see if the load is invalidated from the start of the block to
658 // the load itself.
659 BasicBlock *BB = Load->getParent();
660
662 if (AAR.canInstructionRangeModRef(BB->front(), *Load, Loc, ModRefInfo::Mod))
663 return false; // Pointer is invalidated!
664
665 // Now check every path from the entry block to the load for transparency.
666 // To do this, we perform a depth first search on the inverse CFG from the
667 // loading block.
668 for (BasicBlock *P : predecessors(BB)) {
669 for (BasicBlock *TranspBB : inverse_depth_first(P))
670 if (AAR.canBasicBlockModify(*TranspBB, Loc))
671 return false;
672 }
673 }
674
675 // If the path from the entry of the function to each load is free of
676 // instructions that potentially invalidate the load, we can make the
677 // transformation!
678 return true;
679}
680
681/// Check if callers and callee agree on how promoted arguments would be
682/// passed.
684 const TargetTransformInfo &TTI) {
685 return all_of(F.uses(), [&](const Use &U) {
686 CallBase *CB = dyn_cast<CallBase>(U.getUser());
687 if (!CB)
688 return false;
689
690 const Function *Caller = CB->getCaller();
691 const Function *Callee = CB->getCalledFunction();
692 return TTI.areTypesABICompatible(Caller, Callee, Types);
693 });
694}
695
696/// PromoteArguments - This method checks the specified function to see if there
697/// are any promotable arguments and if it is safe to promote the function (for
698/// example, all callers are direct). If safe to promote some arguments, it
699/// calls the DoPromotion method.
701 unsigned MaxElements, bool IsRecursive) {
702 // Don't perform argument promotion for naked functions; otherwise we can end
703 // up removing parameters that are seemingly 'not used' as they are referred
704 // to in the assembly.
705 if (F->hasFnAttribute(Attribute::Naked))
706 return nullptr;
707
708 // Make sure that it is local to this module.
709 if (!F->hasLocalLinkage())
710 return nullptr;
711
712 // Don't promote arguments for variadic functions. Adding, removing, or
713 // changing non-pack parameters can change the classification of pack
714 // parameters. Frontends encode that classification at the call site in the
715 // IR, while in the callee the classification is determined dynamically based
716 // on the number of registers consumed so far.
717 if (F->isVarArg())
718 return nullptr;
719
720 // Don't transform functions that receive inallocas, as the transformation may
721 // not be safe depending on calling convention.
722 if (F->getAttributes().hasAttrSomewhere(Attribute::InAlloca))
723 return nullptr;
724
725 // First check: see if there are any pointer arguments! If not, quick exit.
726 SmallVector<Argument *, 16> PointerArgs;
727 for (Argument &I : F->args())
728 if (I.getType()->isPointerTy())
729 PointerArgs.push_back(&I);
730 if (PointerArgs.empty())
731 return nullptr;
732
733 // Second check: make sure that all callers are direct callers. We can't
734 // transform functions that have indirect callers. Also see if the function
735 // is self-recursive.
736 for (Use &U : F->uses()) {
737 CallBase *CB = dyn_cast<CallBase>(U.getUser());
738 // Must be a direct call.
739 if (CB == nullptr || !CB->isCallee(&U) ||
740 CB->getFunctionType() != F->getFunctionType())
741 return nullptr;
742
743 // Can't change signature of musttail callee
744 if (CB->isMustTailCall())
745 return nullptr;
746
747 if (CB->getFunction() == F)
748 IsRecursive = true;
749 }
750
751 // Can't change signature of musttail caller
752 // FIXME: Support promoting whole chain of musttail functions
753 for (BasicBlock &BB : *F)
754 if (BB.getTerminatingMustTailCall())
755 return nullptr;
756
757 const DataLayout &DL = F->getParent()->getDataLayout();
758 auto &AAR = FAM.getResult<AAManager>(*F);
759 const auto &TTI = FAM.getResult<TargetIRAnalysis>(*F);
760
761 // Check to see which arguments are promotable. If an argument is promotable,
762 // add it to ArgsToPromote.
764 unsigned NumArgsAfterPromote = F->getFunctionType()->getNumParams();
765 for (Argument *PtrArg : PointerArgs) {
766 // Replace sret attribute with noalias. This reduces register pressure by
767 // avoiding a register copy.
768 if (PtrArg->hasStructRetAttr()) {
769 unsigned ArgNo = PtrArg->getArgNo();
770 F->removeParamAttr(ArgNo, Attribute::StructRet);
771 F->addParamAttr(ArgNo, Attribute::NoAlias);
772 for (Use &U : F->uses()) {
773 CallBase &CB = cast<CallBase>(*U.getUser());
774 CB.removeParamAttr(ArgNo, Attribute::StructRet);
775 CB.addParamAttr(ArgNo, Attribute::NoAlias);
776 }
777 }
778
779 // If we can promote the pointer to its value.
781
782 if (findArgParts(PtrArg, DL, AAR, MaxElements, IsRecursive, ArgParts)) {
784 for (const auto &Pair : ArgParts)
785 Types.push_back(Pair.second.Ty);
786
787 if (areTypesABICompatible(Types, *F, TTI)) {
788 NumArgsAfterPromote += ArgParts.size() - 1;
789 ArgsToPromote.insert({PtrArg, std::move(ArgParts)});
790 }
791 }
792 }
793
794 // No promotable pointer arguments.
795 if (ArgsToPromote.empty())
796 return nullptr;
797
798 if (NumArgsAfterPromote > TTI.getMaxNumArgs())
799 return nullptr;
800
801 return doPromotion(F, FAM, ArgsToPromote);
802}
803
806 LazyCallGraph &CG,
807 CGSCCUpdateResult &UR) {
808 bool Changed = false, LocalChange;
809
810 // Iterate until we stop promoting from this SCC.
811 do {
812 LocalChange = false;
813
815 AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
816
817 bool IsRecursive = C.size() > 1;
818 for (LazyCallGraph::Node &N : C) {
819 Function &OldF = N.getFunction();
820 Function *NewF = promoteArguments(&OldF, FAM, MaxElements, IsRecursive);
821 if (!NewF)
822 continue;
823 LocalChange = true;
824
825 // Directly substitute the functions in the call graph. Note that this
826 // requires the old function to be completely dead and completely
827 // replaced by the new function. It does no call graph updates, it merely
828 // swaps out the particular function mapped to a particular node in the
829 // graph.
830 C.getOuterRefSCC().replaceNodeFunction(N, *NewF);
831 FAM.clear(OldF, OldF.getName());
832 OldF.eraseFromParent();
833
834 PreservedAnalyses FuncPA;
835 FuncPA.preserveSet<CFGAnalyses>();
836 for (auto *U : NewF->users()) {
837 auto *UserF = cast<CallBase>(U)->getFunction();
838 FAM.invalidate(*UserF, FuncPA);
839 }
840 }
841
842 Changed |= LocalChange;
843 } while (LocalChange);
844
845 if (!Changed)
846 return PreservedAnalyses::all();
847
849 // We've cleared out analyses for deleted functions.
851 // We've manually invalidated analyses for functions we've modified.
853 return PA;
854}
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
static bool areTypesABICompatible(ArrayRef< Type * > Types, const Function &F, const TargetTransformInfo &TTI)
Check if callers and callee agree on how promoted arguments would be passed.
static Function * doPromotion(Function *F, FunctionAnalysisManager &FAM, const DenseMap< Argument *, SmallVector< OffsetAndArgPart, 4 > > &ArgsToPromote)
DoPromotion - This method actually performs the promotion of the specified arguments,...
static Function * promoteArguments(Function *F, FunctionAnalysisManager &FAM, unsigned MaxElements, bool IsRecursive)
PromoteArguments - This method checks the specified function to see if there are any promotable argum...
static bool allCallersPassValidPointerForArgument(Argument *Arg, Align NeededAlign, uint64_t NeededDerefBytes)
Return true if we can prove that all callees pass in a valid pointer for the specified function argum...
static Value * createByteGEP(IRBuilderBase &IRB, const DataLayout &DL, Value *Ptr, Type *ResElemTy, int64_t Offset)
static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR, unsigned MaxElements, bool IsRecursive, SmallVectorImpl< OffsetAndArgPart > &ArgPartsVec)
Determine that this argument is safe to promote, and find the argument parts it can be promoted into.
This file contains the simple types necessary to represent the attributes associated with functions a...
This is the interface for LLVM's primary stateless and local alias analysis.
This file provides interfaces used to build and manipulate a call graph, which is a very useful tool ...
This file contains the declarations for the subclasses of Constant, which represent the different fla...
return RetTy
#define LLVM_DEBUG(X)
Definition: Debug.h:101
This file builds on the ADT/GraphTraits.h file to build generic depth first graph iterator.
uint64_t Size
Hexagon Common GEP
This file provides various utilities for inspecting and working with the control flow graph in LLVM I...
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
This file provides utility analysis objects describing memory locations.
This file contains the declarations for metadata subclasses.
uint64_t IntrinsicInst * II
#define P(N)
FunctionAnalysisManager FAM
This header defines various interfaces for pass management in LLVM.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file contains some templates that are useful if you are working with the STL at all.
This file defines the make_scope_exit function, which executes user-defined cleanup logic at scope ex...
This file defines the SmallPtrSet class.
This file defines the SmallVector class.
This file defines the 'Statistic' class, which is designed to be an easy way to expose various metric...
#define STATISTIC(VARNAME, DESC)
Definition: Statistic.h:167
This pass exposes codegen information to IR-level passes.
This defines the Use class.
A manager for alias analyses.
bool canInstructionRangeModRef(const Instruction &I1, const Instruction &I2, const MemoryLocation &Loc, const ModRefInfo Mode)
Check if it is possible for the execution of the specified instructions to mod(according to the mode)...
bool canBasicBlockModify(const BasicBlock &BB, const MemoryLocation &Loc)
Check if it is possible for execution of the specified basic block to modify the location Loc.
Class for arbitrary precision integers.
Definition: APInt.h:77
This templated class represents "all analyses that operate over <a particular IR unit>" (e....
Definition: Analysis.h:47
an instruction to allocate memory on the stack
Definition: Instructions.h:60
void setAlignment(Align Align)
Definition: Instructions.h:137
A container for analyses that lazily runs them and caches their results.
Definition: PassManager.h:321
void clear(IRUnitT &IR, llvm::StringRef Name)
Clear any cached analysis results for a single unit of IR.
void invalidate(IRUnitT &IR, const PreservedAnalyses &PA)
Invalidate cached analyses for an IR unit.
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:473
PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM, LazyCallGraph &CG, CGSCCUpdateResult &UR)
This class represents an incoming formal argument to a Function.
Definition: Argument.h:31
const Function * getParent() const
Definition: Argument.h:43
Type * getParamByValType() const
If this is a byval argument, return its type.
Definition: Function.cpp:230
MaybeAlign getParamAlign() const
If this is a byval or inalloca argument, return its alignment.
Definition: Function.cpp:221
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
A function analysis which provides an AssumptionCache.
AttributeSet getFnAttrs() const
The function attributes are returned.
static AttributeList get(LLVMContext &C, ArrayRef< std::pair< unsigned, Attribute > > Attrs)
Create an AttributeList with the specified parameters in it.
AttributeSet getRetAttrs() const
The attributes for the ret value are returned.
AttributeSet getParamAttrs(unsigned ArgNo) const
The attributes for the argument or parameter at the given index are returned.
std::optional< std::pair< unsigned, std::optional< unsigned > > > getAllocSizeArgs() const
Definition: Attributes.cpp:893
static Attribute getWithAllocSizeArgs(LLVMContext &Context, unsigned ElemSizeArg, const std::optional< unsigned > &NumElemsArg)
Definition: Attributes.cpp:252
LLVM Basic Block Representation.
Definition: BasicBlock.h:60
const Instruction & front() const
Definition: BasicBlock.h:453
Represents analyses that only rely on functions' control flow.
Definition: Analysis.h:70
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1494
void setCallingConv(CallingConv::ID CC)
Definition: InstrTypes.h:1812
void getOperandBundlesAsDefs(SmallVectorImpl< OperandBundleDef > &Defs) const
Return the list of operand bundles attached to this instruction as a vector of OperandBundleDefs.
void removeParamAttr(unsigned ArgNo, Attribute::AttrKind Kind)
Removes the attribute from the given argument.
Definition: InstrTypes.h:1926
Function * getCalledFunction() const
Returns the function called, or null if this is an indirect function invocation or the function signa...
Definition: InstrTypes.h:1750
CallingConv::ID getCallingConv() const
Definition: InstrTypes.h:1808
User::op_iterator arg_begin()
Return the iterator pointing to the beginning of the argument list.
Definition: InstrTypes.h:1670
bool isMustTailCall() const
Tests if this call site must be tail call optimized.
bool isCallee(Value::const_user_iterator UI) const
Determine whether the passed iterator points to the callee operand's Use.
Definition: InstrTypes.h:1761
void setAttributes(AttributeList A)
Set the parameter attributes for this call.
Definition: InstrTypes.h:1831
User::op_iterator arg_end()
Return the iterator pointing to the end of the argument list.
Definition: InstrTypes.h:1676
FunctionType * getFunctionType() const
Definition: InstrTypes.h:1608
AttributeList getAttributes() const
Return the parameter attributes for this call.
Definition: InstrTypes.h:1827
void addParamAttr(unsigned ArgNo, Attribute::AttrKind Kind)
Adds the attribute to the indicated argument.
Definition: InstrTypes.h:1879
Function * getCaller()
Helper to get the caller (the parent function).
static CallInst * Create(FunctionType *Ty, Value *F, const Twine &NameStr, BasicBlock::iterator InsertBefore)
A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:110
ValueT lookup(const_arg_type_t< KeyT > Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:202
std::pair< iterator, bool > try_emplace(KeyT &&Key, Ts &&... Args)
Definition: DenseMap.h:235
unsigned size() const
Definition: DenseMap.h:99
bool empty() const
Definition: DenseMap.h:98
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:220
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:279
A proxy from a FunctionAnalysisManager to an SCC.
void addFnAttr(Attribute::AttrKind Kind)
Add function attributes to this function.
Definition: Function.cpp:588
static Function * Create(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace, const Twine &N="", Module *M=nullptr)
Definition: Function.h:164
void splice(Function::iterator ToIt, Function *FromF)
Transfer all blocks from FromF to this function at ToIt.
Definition: Function.h:742
const BasicBlock & getEntryBlock() const
Definition: Function.h:790
AttributeList getAttributes() const
Return the attribute list for this Function.
Definition: Function.h:340
iterator begin()
Definition: Function.h:806
void eraseFromParent()
eraseFromParent - This method unlinks 'this' from the containing module and deletes it.
Definition: Function.cpp:406
arg_iterator arg_begin()
Definition: Function.h:821
void setAttributes(AttributeList Attrs)
Set the attribute list for this Function.
Definition: Function.h:343
void setIsNewDbgInfoFormat(bool NewVal)
Definition: Function.cpp:100
void copyAttributesFrom(const Function *Src)
copyAttributesFrom - copy all additional attributes (those not needed to create a Function) from the ...
Definition: Function.cpp:798
void copyMetadata(const GlobalObject *Src, unsigned Offset)
Copy metadata from Src, adjusting offsets by Offset.
Definition: Metadata.cpp:1755
Common base class shared among various IRBuilders.
Definition: IRBuilder.h:94
AllocaInst * CreateAlloca(Type *Ty, unsigned AddrSpace, Value *ArraySize=nullptr, const Twine &Name="")
Definition: IRBuilder.h:1773
LoadInst * CreateAlignedLoad(Type *Ty, Value *Ptr, MaybeAlign Align, const char *Name)
Definition: IRBuilder.h:1807
Value * CreatePtrAdd(Value *Ptr, Value *Offset, const Twine &Name="", GEPNoWrapFlags NW=GEPNoWrapFlags::none())
Definition: IRBuilder.h:1976
StoreInst * CreateAlignedStore(Value *Val, Value *Ptr, MaybeAlign Align, bool isVolatile=false)
Definition: IRBuilder.h:1826
ConstantInt * getInt(const APInt &AI)
Get a constant integer value.
Definition: IRBuilder.h:502
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:2666
void setAAMetadata(const AAMDNodes &N)
Sets the AA metadata on this instruction from the AAMDNodes structure.
Definition: Metadata.cpp:1720
bool hasMetadata() const
Return true if this instruction has any metadata attached to it.
Definition: Instruction.h:341
InstListType::iterator eraseFromParent()
This method unlinks 'this' from the containing basic block and deletes it.
const Function * getFunction() const
Return the function this instruction belongs to.
Definition: Instruction.cpp:87
void copyMetadata(const Instruction &SrcInst, ArrayRef< unsigned > WL=ArrayRef< unsigned >())
Copy metadata from SrcInst to this instruction.
Invoke instruction.
static InvokeInst * Create(FunctionType *Ty, Value *Func, BasicBlock *IfNormal, BasicBlock *IfException, ArrayRef< Value * > Args, const Twine &NameStr, BasicBlock::iterator InsertBefore)
A node in the call graph.
An SCC of the call graph.
A lazily constructed view of the call graph of a module.
An instruction for reading from memory.
Definition: Instructions.h:185
static unsigned getPointerOperandIndex()
Definition: Instructions.h:283
Representation for a specific memory location.
static MemoryLocation get(const LoadInst *LI)
Return a location with information about the memory reference by the given instruction.
static PoisonValue * get(Type *T)
Static factory methods - Return an 'poison' object of the specified type.
Definition: Constants.cpp:1814
A set of analyses that are preserved following a run of a transformation pass.
Definition: Analysis.h:109
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: Analysis.h:115
void preserveSet()
Mark an analysis set as preserved.
Definition: Analysis.h:144
void preserve()
Mark an analysis as preserved.
Definition: Analysis.h:129
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:342
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements.
Definition: SmallPtrSet.h:427
bool empty() const
Definition: SmallVector.h:94
size_t size() const
Definition: SmallVector.h:91
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:586
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:950
void push_back(const T &Elt)
Definition: SmallVector.h:426
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1209
An instruction for storing to memory.
Definition: Instructions.h:318
static unsigned getPointerOperandIndex()
Definition: Instructions.h:420
Analysis pass providing the TargetTransformInfo.
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
static UndefValue * get(Type *T)
Static factory methods - Return an 'undef' object of the specified type.
Definition: Constants.cpp:1795
A Use represents the edge between a Value definition and its users.
Definition: Use.h:43
LLVM Value Representation.
Definition: Value.h:74
void setName(const Twine &Name)
Change the name of the value.
Definition: Value.cpp:377
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:534
iterator_range< user_iterator > users()
Definition: Value.h:421
bool use_empty() const
Definition: Value.h:344
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:309
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:383
self_iterator getIterator()
Definition: ilist_node.h:109
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
void updateMinLegalVectorWidthAttr(Function &Fn, uint64_t Width)
Update min-legal-vector-width if it is in Attribute and less than Width.
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
@ Offset
Definition: DWP.cpp:456
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1722
void PromoteMemToReg(ArrayRef< AllocaInst * > Allocas, DominatorTree &DT, AssumptionCache *AC=nullptr)
Promote the specified list of alloca instructions into scalar registers, inserting PHI nodes as appro...
detail::scope_exit< std::decay_t< Callable > > make_scope_exit(Callable &&F)
Definition: ScopeExit.h:59
bool isAligned(Align Lhs, uint64_t SizeInBytes)
Checks that SizeInBytes is a multiple of the alignment.
Definition: Alignment.h:145
bool isDereferenceableAndAlignedPointer(const Value *V, Type *Ty, Align Alignment, const DataLayout &DL, const Instruction *CtxI=nullptr, AssumptionCache *AC=nullptr, const DominatorTree *DT=nullptr, const TargetLibraryInfo *TLI=nullptr)
Returns true if V is always a dereferenceable pointer with alignment greater or equal than requested.
Definition: Loads.cpp:201
void append_range(Container &C, Range &&R)
Wrapper function to append range R to container C.
Definition: STLExtras.h:2067
bool isAllocaPromotable(const AllocaInst *AI)
Return true if this alloca is legal for promotion.
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1647
iterator_range< idf_iterator< T > > inverse_depth_first(const T &G)
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
bool RecursivelyDeleteTriviallyDeadInstructionsPermissive(SmallVectorImpl< WeakTrackingVH > &DeadInsts, const TargetLibraryInfo *TLI=nullptr, MemorySSAUpdater *MSSAU=nullptr, std::function< void(Value *)> AboutToDeleteCallback=std::function< void(Value *)>())
Same functionality as RecursivelyDeleteTriviallyDeadInstructions, but allow instructions that are not...
Definition: Local.cpp:555
bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I)
Return true if this function can prove that the instruction I will always transfer execution to one o...
auto predecessors(const MachineBasicBlock *BB)
#define N
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:39
Support structure for SCC passes to communicate updates the call graph back to the CGSCC pass manager...
Function object to check whether the first component of a container supported by std::get (like std::...
Definition: STLExtras.h:1450