1//==- AArch64PromoteConstant.cpp - Promote constant to global for AArch64 --==//
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 AArch64PromoteConstant pass which promotes constants
10// to global variables when this is likely to be more efficient. Currently only
11// types related to constant vector (i.e., constant vector, array of constant
12// vectors, constant structure with a constant vector field, etc.) are promoted
13// to global variables. Constant vectors are likely to be lowered in target
14// constant pool during instruction selection already; therefore, the access
15// will remain the same (memory load), but the structure types are not split
16// into different constant pool accesses for each field. A bonus side effect is
17// that created globals may be merged by the global merge pass.
18//
19// FIXME: This pass may be useful for other targets too.
20//===----------------------------------------------------------------------===//
21
22#include "AArch64.h"
23#include "llvm/ADT/DenseMap.h"
24#include "llvm/ADT/SmallVector.h"
25#include "llvm/ADT/Statistic.h"
26#include "llvm/IR/BasicBlock.h"
27#include "llvm/IR/Constant.h"
28#include "llvm/IR/Constants.h"
29#include "llvm/IR/Dominators.h"
30#include "llvm/IR/Function.h"
31#include "llvm/IR/GlobalValue.h"
32#include "llvm/IR/GlobalVariable.h"
33#include "llvm/IR/IRBuilder.h"
34#include "llvm/IR/InlineAsm.h"
35#include "llvm/IR/InstIterator.h"
36#include "llvm/IR/Instruction.h"
37#include "llvm/IR/Instructions.h"
38#include "llvm/IR/IntrinsicInst.h"
39#include "llvm/IR/Module.h"
40#include "llvm/IR/Type.h"
41#include "llvm/InitializePasses.h"
42#include "llvm/Pass.h"
43#include "llvm/Support/Casting.h"
44#include "llvm/Support/CommandLine.h"
45#include "llvm/Support/Debug.h"
46#include "llvm/Support/raw_ostream.h"
47#include <algorithm>
48#include <cassert>
49#include <utility>
50
51using namespace llvm;
52
53#define DEBUG_TYPE "aarch64-promote-const"
54
55// Stress testing mode - disable heuristics.
56static cl::opt<bool> Stress("aarch64-stress-promote-const", cl::Hidden,
57 cl::desc("Promote all vector constants"));
58
59STATISTIC(NumPromoted, "Number of promoted constants");
60STATISTIC(NumPromotedUses, "Number of promoted constants uses");
61
62//===----------------------------------------------------------------------===//
63// AArch64PromoteConstant
64//===----------------------------------------------------------------------===//
65
66namespace {
67
68/// Promotes interesting constant into global variables.
69/// The motivating example is:
70/// static const uint16_t TableA[32] = {
71/// 41944, 40330, 38837, 37450, 36158, 34953, 33826, 32768,
72/// 31776, 30841, 29960, 29128, 28340, 27595, 26887, 26215,
73/// 25576, 24967, 24386, 23832, 23302, 22796, 22311, 21846,
74/// 21400, 20972, 20561, 20165, 19785, 19419, 19066, 18725,
75/// };
76///
77/// uint8x16x4_t LoadStatic(void) {
78/// uint8x16x4_t ret;
79/// ret.val[0] = vld1q_u16(TableA + 0);
80/// ret.val[1] = vld1q_u16(TableA + 8);
81/// ret.val[2] = vld1q_u16(TableA + 16);
82/// ret.val[3] = vld1q_u16(TableA + 24);
83/// return ret;
84/// }
85///
86/// The constants in this example are folded into the uses. Thus, 4 different
87/// constants are created.
88///
89/// As their type is vector the cheapest way to create them is to load them
90/// for the memory.
91///
92/// Therefore the final assembly final has 4 different loads. With this pass
93/// enabled, only one load is issued for the constants.
94class AArch64PromoteConstant : public ModulePass {
95public:
96 struct PromotedConstant {
97 bool ShouldConvert = false;
98 GlobalVariable *GV = nullptr;
99 };
100 using PromotionCacheTy = SmallDenseMap<Constant *, PromotedConstant, 16>;
101
102 struct UpdateRecord {
103 Constant *C;
104 Instruction *User;
105 unsigned Op;
106
107 UpdateRecord(Constant *C, Instruction *User, unsigned Op)
108 : C(C), User(User), Op(Op) {}
109 };
110
111 static char ID;
112
113 AArch64PromoteConstant() : ModulePass(ID) {
114 initializeAArch64PromoteConstantPass(*PassRegistry::getPassRegistry());
115 }
116
117 StringRef getPassName() const override { return "AArch64 Promote Constant"; }
118
119 /// Iterate over the functions and promote the interesting constants into
120 /// global variables with module scope.
121 bool runOnModule(Module &M) override {
122 LLVM_DEBUG(dbgs() << getPassName() << '\n');
123 if (skipModule(M))
124 return false;
125 bool Changed = false;
126 PromotionCacheTy PromotionCache;
127 for (auto &MF : M) {
128 Changed |= runOnFunction(F&: MF, PromotionCache);
129 }
130 return Changed;
131 }
132
133private:
134 /// Look for interesting constants used within the given function.
135 /// Promote them into global variables, load these global variables within
136 /// the related function, so that the number of inserted load is minimal.
137 bool runOnFunction(Function &F, PromotionCacheTy &PromotionCache);
138
139 // This transformation requires dominator info
140 void getAnalysisUsage(AnalysisUsage &AU) const override {
141 AU.setPreservesCFG();
142 AU.addRequired<DominatorTreeWrapperPass>();
143 AU.addPreserved<DominatorTreeWrapperPass>();
144 }
145
146 /// Type to store a list of Uses.
147 using Uses = SmallVector<std::pair<Instruction *, unsigned>, 4>;
148 /// Map an insertion point to all the uses it dominates.
149 using InsertionPoints = DenseMap<Instruction *, Uses>;
150
151 /// Find the closest point that dominates the given Use.
152 Instruction *findInsertionPoint(Instruction &User, unsigned OpNo);
153
154 /// Check if the given insertion point is dominated by an existing
155 /// insertion point.
156 /// If true, the given use is added to the list of dominated uses for
157 /// the related existing point.
158 /// \param NewPt the insertion point to be checked
159 /// \param User the user of the constant
160 /// \param OpNo the operand number of the use
161 /// \param InsertPts existing insertion points
162 /// \pre NewPt and all instruction in InsertPts belong to the same function
163 /// \return true if one of the insertion point in InsertPts dominates NewPt,
164 /// false otherwise
165 bool isDominated(Instruction *NewPt, Instruction *User, unsigned OpNo,
166 InsertionPoints &InsertPts);
167
168 /// Check if the given insertion point can be merged with an existing
169 /// insertion point in a common dominator.
170 /// If true, the given use is added to the list of the created insertion
171 /// point.
172 /// \param NewPt the insertion point to be checked
173 /// \param User the user of the constant
174 /// \param OpNo the operand number of the use
175 /// \param InsertPts existing insertion points
176 /// \pre NewPt and all instruction in InsertPts belong to the same function
177 /// \pre isDominated returns false for the exact same parameters.
178 /// \return true if it exists an insertion point in InsertPts that could
179 /// have been merged with NewPt in a common dominator,
180 /// false otherwise
181 bool tryAndMerge(Instruction *NewPt, Instruction *User, unsigned OpNo,
182 InsertionPoints &InsertPts);
183
184 /// Compute the minimal insertion points to dominates all the interesting
185 /// uses of value.
186 /// Insertion points are group per function and each insertion point
187 /// contains a list of all the uses it dominates within the related function
188 /// \param User the user of the constant
189 /// \param OpNo the operand number of the constant
190 /// \param[out] InsertPts output storage of the analysis
191 void computeInsertionPoint(Instruction *User, unsigned OpNo,
192 InsertionPoints &InsertPts);
193
194 /// Insert a definition of a new global variable at each point contained in
195 /// InsPtsPerFunc and update the related uses (also contained in
196 /// InsPtsPerFunc).
197 void insertDefinitions(Function &F, GlobalVariable &GV,
198 InsertionPoints &InsertPts);
199
200 /// Do the constant promotion indicated by the Updates records, keeping track
201 /// of globals in PromotionCache.
202 void promoteConstants(Function &F, SmallVectorImpl<UpdateRecord> &Updates,
203 PromotionCacheTy &PromotionCache);
204
205 /// Transfer the list of dominated uses of IPI to NewPt in InsertPts.
206 /// Append Use to this list and delete the entry of IPI in InsertPts.
207 static void appendAndTransferDominatedUses(Instruction *NewPt,
208 Instruction *User, unsigned OpNo,
209 InsertionPoints::iterator &IPI,
210 InsertionPoints &InsertPts) {
211 // Record the dominated use.
212 IPI->second.emplace_back(Args&: User, Args&: OpNo);
213 // Transfer the dominated uses of IPI to NewPt
214 // Inserting into the DenseMap may invalidate existing iterator.
215 // Keep a copy of the key to find the iterator to erase. Keep a copy of the
216 // value so that we don't have to dereference IPI->second.
217 Instruction *OldInstr = IPI->first;
218 Uses OldUses = std::move(IPI->second);
219 InsertPts[NewPt] = std::move(OldUses);
220 // Erase IPI.
221 InsertPts.erase(Val: OldInstr);
222 }
223};
224
225} // end anonymous namespace
226
227char AArch64PromoteConstant::ID = 0;
228
229INITIALIZE_PASS_BEGIN(AArch64PromoteConstant, "aarch64-promote-const",
230 "AArch64 Promote Constant Pass", false, false)
231INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
232INITIALIZE_PASS_END(AArch64PromoteConstant, "aarch64-promote-const",
233 "AArch64 Promote Constant Pass", false, false)
234
235ModulePass *llvm::createAArch64PromoteConstantPass() {
236 return new AArch64PromoteConstant();
237}
238
239/// Check if the given type uses a vector type.
240static bool isConstantUsingVectorTy(const Type *CstTy) {
241 if (CstTy->isVectorTy())
242 return true;
243 if (CstTy->isStructTy()) {
244 for (unsigned EltIdx = 0, EndEltIdx = CstTy->getStructNumElements();
245 EltIdx < EndEltIdx; ++EltIdx)
246 if (isConstantUsingVectorTy(CstTy: CstTy->getStructElementType(N: EltIdx)))
247 return true;
248 } else if (CstTy->isArrayTy())
249 return isConstantUsingVectorTy(CstTy: CstTy->getArrayElementType());
250 return false;
251}
252
253// Returns true if \p C contains only ConstantData leafs and no global values,
254// block addresses or constant expressions. Traverses ConstantAggregates.
255static bool containsOnlyConstantData(const Constant *C) {
256 if (isa<ConstantData>(Val: C))
257 return true;
258
259 if (isa<GlobalValue>(Val: C) || isa<BlockAddress>(Val: C) || isa<ConstantExpr>(Val: C))
260 return false;
261
262 return all_of(Range: C->operands(), P: [](const Use &U) {
263 return containsOnlyConstantData(C: cast<Constant>(Val: &U));
264 });
265}
266
267/// Check if the given use (Instruction + OpIdx) of Cst should be converted into
268/// a load of a global variable initialized with Cst.
269/// A use should be converted if it is legal to do so.
270/// For instance, it is not legal to turn the mask operand of a shuffle vector
271/// into a load of a global variable.
272static bool shouldConvertUse(const Constant *Cst, const Instruction *Instr,
273 unsigned OpIdx) {
274 // shufflevector instruction expects a const for the mask argument, i.e., the
275 // third argument. Do not promote this use in that case.
276 if (isa<const ShuffleVectorInst>(Val: Instr) && OpIdx == 2)
277 return false;
278
279 // extractvalue instruction expects a const idx.
280 if (isa<const ExtractValueInst>(Val: Instr) && OpIdx > 0)
281 return false;
282
283 // extractvalue instruction expects a const idx.
284 if (isa<const InsertValueInst>(Val: Instr) && OpIdx > 1)
285 return false;
286
287 if (isa<const AllocaInst>(Val: Instr) && OpIdx > 0)
288 return false;
289
290 // Alignment argument must be constant.
291 if (isa<const LoadInst>(Val: Instr) && OpIdx > 0)
292 return false;
293
294 // Alignment argument must be constant.
295 if (isa<const StoreInst>(Val: Instr) && OpIdx > 1)
296 return false;
297
298 // Index must be constant.
299 if (isa<const GetElementPtrInst>(Val: Instr) && OpIdx > 0)
300 return false;
301
302 // Personality function and filters must be constant.
303 // Give up on that instruction.
304 if (isa<const LandingPadInst>(Val: Instr))
305 return false;
306
307 // Switch instruction expects constants to compare to.
308 if (isa<const SwitchInst>(Val: Instr))
309 return false;
310
311 // Expected address must be a constant.
312 if (isa<const IndirectBrInst>(Val: Instr))
313 return false;
314
315 // Do not mess with intrinsics.
316 if (isa<const IntrinsicInst>(Val: Instr))
317 return false;
318
319 // Do not mess with inline asm.
320 const CallInst *CI = dyn_cast<const CallInst>(Val: Instr);
321 return !(CI && CI->isInlineAsm());
322}
323
324/// Check if the given Cst should be converted into
325/// a load of a global variable initialized with Cst.
326/// A constant should be converted if it is likely that the materialization of
327/// the constant will be tricky. Thus, we give up on zero or undef values.
328///
329/// \todo Currently, accept only vector related types.
330/// Also we give up on all simple vector type to keep the existing
331/// behavior. Otherwise, we should push here all the check of the lowering of
332/// BUILD_VECTOR. By giving up, we lose the potential benefit of merging
333/// constant via global merge and the fact that the same constant is stored
334/// only once with this method (versus, as many function that uses the constant
335/// for the regular approach, even for float).
336/// Again, the simplest solution would be to promote every
337/// constant and rematerialize them when they are actually cheap to create.
338static bool shouldConvertImpl(const Constant *Cst) {
339 if (isa<const UndefValue>(Val: Cst))
340 return false;
341
342 // FIXME: In some cases, it may be interesting to promote in memory
343 // a zero initialized constant.
344 // E.g., when the type of Cst require more instructions than the
345 // adrp/add/load sequence or when this sequence can be shared by several
346 // instances of Cst.
347 // Ideally, we could promote this into a global and rematerialize the constant
348 // when it was a bad idea.
349 if (Cst->isZeroValue())
350 return false;
351
352 if (Stress)
353 return true;
354
355 // FIXME: see function \todo
356 if (Cst->getType()->isVectorTy())
357 return false;
358 return isConstantUsingVectorTy(CstTy: Cst->getType());
359}
360
361static bool
362shouldConvert(Constant &C,
363 AArch64PromoteConstant::PromotionCacheTy &PromotionCache) {
364 auto Converted = PromotionCache.insert(
365 KV: std::make_pair(x: &C, y: AArch64PromoteConstant::PromotedConstant()));
366 if (Converted.second)
367 Converted.first->second.ShouldConvert = shouldConvertImpl(Cst: &C);
368 return Converted.first->second.ShouldConvert;
369}
370
371Instruction *AArch64PromoteConstant::findInsertionPoint(Instruction &User,
372 unsigned OpNo) {
373 // If this user is a phi, the insertion point is in the related
374 // incoming basic block.
375 if (PHINode *PhiInst = dyn_cast<PHINode>(Val: &User))
376 return PhiInst->getIncomingBlock(i: OpNo)->getTerminator();
377
378 return &User;
379}
380
381bool AArch64PromoteConstant::isDominated(Instruction *NewPt, Instruction *User,
382 unsigned OpNo,
383 InsertionPoints &InsertPts) {
384 DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(
385 F&: *NewPt->getParent()->getParent()).getDomTree();
386
387 // Traverse all the existing insertion points and check if one is dominating
388 // NewPt. If it is, remember that.
389 for (auto &IPI : InsertPts) {
390 if (NewPt == IPI.first || DT.dominates(Def: IPI.first, User: NewPt) ||
391 // When IPI.first is a terminator instruction, DT may think that
392 // the result is defined on the edge.
393 // Here we are testing the insertion point, not the definition.
394 (IPI.first->getParent() != NewPt->getParent() &&
395 DT.dominates(A: IPI.first->getParent(), B: NewPt->getParent()))) {
396 // No need to insert this point. Just record the dominated use.
397 LLVM_DEBUG(dbgs() << "Insertion point dominated by:\n");
398 LLVM_DEBUG(IPI.first->print(dbgs()));
399 LLVM_DEBUG(dbgs() << '\n');
400 IPI.second.emplace_back(Args&: User, Args&: OpNo);
401 return true;
402 }
403 }
404 return false;
405}
406
407bool AArch64PromoteConstant::tryAndMerge(Instruction *NewPt, Instruction *User,
408 unsigned OpNo,
409 InsertionPoints &InsertPts) {
410 DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(
411 F&: *NewPt->getParent()->getParent()).getDomTree();
412 BasicBlock *NewBB = NewPt->getParent();
413
414 // Traverse all the existing insertion point and check if one is dominated by
415 // NewPt and thus useless or can be combined with NewPt into a common
416 // dominator.
417 for (InsertionPoints::iterator IPI = InsertPts.begin(),
418 EndIPI = InsertPts.end();
419 IPI != EndIPI; ++IPI) {
420 BasicBlock *CurBB = IPI->first->getParent();
421 if (NewBB == CurBB) {
422 // Instructions are in the same block.
423 // By construction, NewPt is dominating the other.
424 // Indeed, isDominated returned false with the exact same arguments.
425 LLVM_DEBUG(dbgs() << "Merge insertion point with:\n");
426 LLVM_DEBUG(IPI->first->print(dbgs()));
427 LLVM_DEBUG(dbgs() << "\nat considered insertion point.\n");
428 appendAndTransferDominatedUses(NewPt, User, OpNo, IPI, InsertPts);
429 return true;
430 }
431
432 // Look for a common dominator
433 BasicBlock *CommonDominator = DT.findNearestCommonDominator(A: NewBB, B: CurBB);
434 // If none exists, we cannot merge these two points.
435 if (!CommonDominator)
436 continue;
437
438 if (CommonDominator != NewBB) {
439 // By construction, the CommonDominator cannot be CurBB.
440 assert(CommonDominator != CurBB &&
441 "Instruction has not been rejected during isDominated check!");
442 // Take the last instruction of the CommonDominator as insertion point
443 NewPt = CommonDominator->getTerminator();
444 }
445 // else, CommonDominator is the block of NewBB, hence NewBB is the last
446 // possible insertion point in that block.
447 LLVM_DEBUG(dbgs() << "Merge insertion point with:\n");
448 LLVM_DEBUG(IPI->first->print(dbgs()));
449 LLVM_DEBUG(dbgs() << '\n');
450 LLVM_DEBUG(NewPt->print(dbgs()));
451 LLVM_DEBUG(dbgs() << '\n');
452 appendAndTransferDominatedUses(NewPt, User, OpNo, IPI, InsertPts);
453 return true;
454 }
455 return false;
456}
457
458void AArch64PromoteConstant::computeInsertionPoint(
459 Instruction *User, unsigned OpNo, InsertionPoints &InsertPts) {
460 LLVM_DEBUG(dbgs() << "Considered use, opidx " << OpNo << ":\n");
461 LLVM_DEBUG(User->print(dbgs()));
462 LLVM_DEBUG(dbgs() << '\n');
463
464 Instruction *InsertionPoint = findInsertionPoint(User&: *User, OpNo);
465
466 LLVM_DEBUG(dbgs() << "Considered insertion point:\n");
467 LLVM_DEBUG(InsertionPoint->print(dbgs()));
468 LLVM_DEBUG(dbgs() << '\n');
469
470 if (isDominated(NewPt: InsertionPoint, User, OpNo, InsertPts))
471 return;
472 // This insertion point is useful, check if we can merge some insertion
473 // point in a common dominator or if NewPt dominates an existing one.
474 if (tryAndMerge(NewPt: InsertionPoint, User, OpNo, InsertPts))
475 return;
476
477 LLVM_DEBUG(dbgs() << "Keep considered insertion point\n");
478
479 // It is definitely useful by its own
480 InsertPts[InsertionPoint].emplace_back(Args&: User, Args&: OpNo);
481}
482
483static void ensurePromotedGV(Function &F, Constant &C,
484 AArch64PromoteConstant::PromotedConstant &PC) {
485 assert(PC.ShouldConvert &&
486 "Expected that we should convert this to a global");
487 if (PC.GV)
488 return;
489 PC.GV = new GlobalVariable(
490 *F.getParent(), C.getType(), true, GlobalValue::InternalLinkage, nullptr,
491 "_PromotedConst", nullptr, GlobalVariable::NotThreadLocal);
492 PC.GV->setInitializer(&C);
493 LLVM_DEBUG(dbgs() << "Global replacement: ");
494 LLVM_DEBUG(PC.GV->print(dbgs()));
495 LLVM_DEBUG(dbgs() << '\n');
496 ++NumPromoted;
497}
498
499void AArch64PromoteConstant::insertDefinitions(Function &F,
500 GlobalVariable &PromotedGV,
501 InsertionPoints &InsertPts) {
502#ifndef NDEBUG
503 // Do more checking for debug purposes.
504 DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
505#endif
506 assert(!InsertPts.empty() && "Empty uses does not need a definition");
507
508 for (const auto &IPI : InsertPts) {
509 // Create the load of the global variable.
510 IRBuilder<> Builder(IPI.first);
511 LoadInst *LoadedCst =
512 Builder.CreateLoad(Ty: PromotedGV.getValueType(), Ptr: &PromotedGV);
513 LLVM_DEBUG(dbgs() << "**********\n");
514 LLVM_DEBUG(dbgs() << "New def: ");
515 LLVM_DEBUG(LoadedCst->print(dbgs()));
516 LLVM_DEBUG(dbgs() << '\n');
517
518 // Update the dominated uses.
519 for (auto Use : IPI.second) {
520#ifndef NDEBUG
521 assert(DT.dominates(LoadedCst,
522 findInsertionPoint(*Use.first, Use.second)) &&
523 "Inserted definition does not dominate all its uses!");
524#endif
525 LLVM_DEBUG({
526 dbgs() << "Use to update " << Use.second << ":";
527 Use.first->print(dbgs());
528 dbgs() << '\n';
529 });
530 Use.first->setOperand(i: Use.second, Val: LoadedCst);
531 ++NumPromotedUses;
532 }
533 }
534}
535
536void AArch64PromoteConstant::promoteConstants(
537 Function &F, SmallVectorImpl<UpdateRecord> &Updates,
538 PromotionCacheTy &PromotionCache) {
539 // Promote the constants.
540 for (auto U = Updates.begin(), E = Updates.end(); U != E;) {
541 LLVM_DEBUG(dbgs() << "** Compute insertion points **\n");
542 auto First = U;
543 Constant *C = First->C;
544 InsertionPoints InsertPts;
545 do {
546 computeInsertionPoint(User: U->User, OpNo: U->Op, InsertPts);
547 } while (++U != E && U->C == C);
548
549 auto &Promotion = PromotionCache[C];
550 ensurePromotedGV(F, C&: *C, PC&: Promotion);
551 insertDefinitions(F, PromotedGV&: *Promotion.GV, InsertPts);
552 }
553}
554
555bool AArch64PromoteConstant::runOnFunction(Function &F,
556 PromotionCacheTy &PromotionCache) {
557 // Look for instructions using constant vector. Promote that constant to a
558 // global variable. Create as few loads of this variable as possible and
559 // update the uses accordingly.
560 SmallVector<UpdateRecord, 64> Updates;
561 for (Instruction &I : instructions(F: &F)) {
562 // Traverse the operand, looking for constant vectors. Replace them by a
563 // load of a global variable of constant vector type.
564 for (Use &U : I.operands()) {
565 Constant *Cst = dyn_cast<Constant>(Val&: U);
566 // There is no point in promoting global values as they are already
567 // global. Do not promote constants containing constant expression, global
568 // values or blockaddresses either, as they may require some code
569 // expansion.
570 if (!Cst || isa<GlobalValue>(Val: Cst) || !containsOnlyConstantData(C: Cst))
571 continue;
572
573 // Check if this constant is worth promoting.
574 if (!shouldConvert(C&: *Cst, PromotionCache))
575 continue;
576
577 // Check if this use should be promoted.
578 unsigned OpNo = &U - I.op_begin();
579 if (!shouldConvertUse(Cst, Instr: &I, OpIdx: OpNo))
580 continue;
581
582 Updates.emplace_back(Args&: Cst, Args: &I, Args&: OpNo);
583 }
584 }
585
586 if (Updates.empty())
587 return false;
588
589 promoteConstants(F, Updates, PromotionCache);
590 return true;
591}
592