1//===- InstCombineCasts.cpp -----------------------------------------------===//
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 visit functions for cast operations.
10//
11//===----------------------------------------------------------------------===//
12
13#include "InstCombineInternal.h"
14#include "llvm/ADT/APInt.h"
15#include "llvm/ADT/DenseMap.h"
16#include "llvm/ADT/STLExtras.h"
17#include "llvm/ADT/STLFunctionalExtras.h"
18#include "llvm/ADT/SetVector.h"
19#include "llvm/ADT/SmallVector.h"
20#include "llvm/Analysis/ConstantFolding.h"
21#include "llvm/IR/DataLayout.h"
22#include "llvm/IR/DebugInfo.h"
23#include "llvm/IR/Instruction.h"
24#include "llvm/IR/PatternMatch.h"
25#include "llvm/IR/Type.h"
26#include "llvm/IR/Value.h"
27#include "llvm/Support/KnownBits.h"
28#include "llvm/Transforms/InstCombine/InstCombiner.h"
29#include <iterator>
30#include <optional>
31
32using namespace llvm;
33using namespace PatternMatch;
34
35#define DEBUG_TYPE "instcombine"
36
37using EvaluatedMap = SmallDenseMap<Value *, Value *, 8>;
38
39static Value *EvaluateInDifferentTypeImpl(Value *V, Type *Ty, bool isSigned,
40 InstCombinerImpl &IC,
41 EvaluatedMap &Processed) {
42 // Since we cover transformation of instructions with multiple users, we might
43 // come to the same node via multiple paths. We should not create a
44 // replacement for every single one of them though.
45 if (Value *Result = Processed.lookup(Val: V))
46 return Result;
47
48 if (Constant *C = dyn_cast<Constant>(Val: V))
49 return ConstantFoldIntegerCast(C, DestTy: Ty, IsSigned: isSigned, DL: IC.getDataLayout());
50
51 // Otherwise, it must be an instruction.
52 Instruction *I = cast<Instruction>(Val: V);
53 Instruction *Res = nullptr;
54 unsigned Opc = I->getOpcode();
55 switch (Opc) {
56 case Instruction::Add:
57 case Instruction::Sub:
58 case Instruction::Mul:
59 case Instruction::And:
60 case Instruction::Or:
61 case Instruction::Xor:
62 case Instruction::AShr:
63 case Instruction::LShr:
64 case Instruction::Shl:
65 case Instruction::UDiv:
66 case Instruction::URem: {
67 Value *LHS = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 0), Ty, isSigned, IC,
68 Processed);
69 Value *RHS = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty, isSigned, IC,
70 Processed);
71 Res = BinaryOperator::Create(Op: (Instruction::BinaryOps)Opc, S1: LHS, S2: RHS);
72 if (Opc == Instruction::LShr || Opc == Instruction::AShr)
73 Res->setIsExact(I->isExact());
74 break;
75 }
76 case Instruction::Trunc:
77 case Instruction::ZExt:
78 case Instruction::SExt:
79 // If the source type of the cast is the type we're trying for then we can
80 // just return the source. There's no need to insert it because it is not
81 // new.
82 if (I->getOperand(i: 0)->getType() == Ty)
83 return I->getOperand(i: 0);
84
85 // Otherwise, must be the same type of cast, so just reinsert a new one.
86 // This also handles the case of zext(trunc(x)) -> zext(x).
87 Res = CastInst::CreateIntegerCast(S: I->getOperand(i: 0), Ty,
88 isSigned: Opc == Instruction::SExt);
89 break;
90 case Instruction::Select: {
91 Value *True = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty, isSigned,
92 IC, Processed);
93 Value *False = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 2), Ty, isSigned,
94 IC, Processed);
95 Res = SelectInst::Create(C: I->getOperand(i: 0), S1: True, S2: False);
96 break;
97 }
98 case Instruction::PHI: {
99 PHINode *OPN = cast<PHINode>(Val: I);
100 PHINode *NPN = PHINode::Create(Ty, NumReservedValues: OPN->getNumIncomingValues());
101 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
102 Value *V = EvaluateInDifferentTypeImpl(V: OPN->getIncomingValue(i), Ty,
103 isSigned, IC, Processed);
104 NPN->addIncoming(V, BB: OPN->getIncomingBlock(i));
105 }
106 Res = NPN;
107 break;
108 }
109 case Instruction::FPToUI:
110 case Instruction::FPToSI:
111 Res = CastInst::Create(static_cast<Instruction::CastOps>(Opc),
112 S: I->getOperand(i: 0), Ty);
113 break;
114 case Instruction::Call:
115 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
116 switch (II->getIntrinsicID()) {
117 default:
118 llvm_unreachable("Unsupported call!");
119 case Intrinsic::vscale: {
120 Function *Fn = Intrinsic::getOrInsertDeclaration(
121 M: I->getModule(), id: Intrinsic::vscale, Tys: {Ty});
122 Res = CallInst::Create(Ty: Fn->getFunctionType(), F: Fn);
123 break;
124 }
125 }
126 }
127 break;
128 case Instruction::ShuffleVector: {
129 auto *ScalarTy = cast<VectorType>(Val: Ty)->getElementType();
130 auto *VTy = cast<VectorType>(Val: I->getOperand(i: 0)->getType());
131 auto *FixedTy = VectorType::get(ElementType: ScalarTy, EC: VTy->getElementCount());
132 Value *Op0 = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 0), Ty: FixedTy,
133 isSigned, IC, Processed);
134 Value *Op1 = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty: FixedTy,
135 isSigned, IC, Processed);
136 Res = new ShuffleVectorInst(Op0, Op1,
137 cast<ShuffleVectorInst>(Val: I)->getShuffleMask());
138 break;
139 }
140 default:
141 // TODO: Can handle more cases here.
142 llvm_unreachable("Unreachable!");
143 }
144
145 Res->takeName(V: I);
146 Value *Result = IC.InsertNewInstWith(New: Res, Old: I->getIterator());
147 // There is no need in keeping track of the old value/new value relationship
148 // when we have only one user, we came have here from that user and no-one
149 // else cares.
150 if (!V->hasOneUse())
151 Processed[V] = Result;
152
153 return Result;
154}
155
156/// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns
157/// true for, actually insert the code to evaluate the expression.
158Value *InstCombinerImpl::EvaluateInDifferentType(Value *V, Type *Ty,
159 bool isSigned) {
160 EvaluatedMap Processed;
161 return EvaluateInDifferentTypeImpl(V, Ty, isSigned, IC&: *this, Processed);
162}
163
164Instruction::CastOps
165InstCombinerImpl::isEliminableCastPair(const CastInst *CI1,
166 const CastInst *CI2) {
167 Type *SrcTy = CI1->getSrcTy();
168 Type *MidTy = CI1->getDestTy();
169 Type *DstTy = CI2->getDestTy();
170
171 Instruction::CastOps firstOp = CI1->getOpcode();
172 Instruction::CastOps secondOp = CI2->getOpcode();
173 Type *SrcIntPtrTy =
174 SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr;
175 Type *DstIntPtrTy =
176 DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr;
177 unsigned Res = CastInst::isEliminableCastPair(firstOpcode: firstOp, secondOpcode: secondOp, SrcTy, MidTy,
178 DstTy, DL: &DL);
179
180 // We don't want to form an inttoptr or ptrtoint that converts to an integer
181 // type that differs from the pointer size.
182 if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
183 (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
184 Res = 0;
185
186 return Instruction::CastOps(Res);
187}
188
189/// Implement the transforms common to all CastInst visitors.
190Instruction *InstCombinerImpl::commonCastTransforms(CastInst &CI) {
191 Value *Src = CI.getOperand(i_nocapture: 0);
192 Type *Ty = CI.getType();
193
194 if (Value *Res =
195 simplifyCastInst(CastOpc: CI.getOpcode(), Op: Src, Ty, Q: SQ.getWithInstruction(I: &CI)))
196 return replaceInstUsesWith(I&: CI, V: Res);
197
198 // Try to eliminate a cast of a cast.
199 if (auto *CSrc = dyn_cast<CastInst>(Val: Src)) { // A->B->C cast
200 if (Instruction::CastOps NewOpc = isEliminableCastPair(CI1: CSrc, CI2: &CI)) {
201 // The first cast (CSrc) is eliminable so we need to fix up or replace
202 // the second cast (CI). CSrc will then have a good chance of being dead.
203 auto *Res = CastInst::Create(NewOpc, S: CSrc->getOperand(i_nocapture: 0), Ty);
204 // Point debug users of the dying cast to the new one.
205 if (CSrc->hasOneUse())
206 replaceAllDbgUsesWith(From&: *CSrc, To&: *Res, DomPoint&: CI, DT);
207 return Res;
208 }
209 }
210
211 if (auto *Sel = dyn_cast<SelectInst>(Val: Src)) {
212 // We are casting a select. Try to fold the cast into the select if the
213 // select does not have a compare instruction with matching operand types
214 // or the select is likely better done in a narrow type.
215 // Creating a select with operands that are different sizes than its
216 // condition may inhibit other folds and lead to worse codegen.
217 auto *Cmp = dyn_cast<CmpInst>(Val: Sel->getCondition());
218 if (!Cmp || Cmp->getOperand(i_nocapture: 0)->getType() != Sel->getType() ||
219 (CI.getOpcode() == Instruction::Trunc &&
220 shouldChangeType(From: CI.getSrcTy(), To: CI.getType()))) {
221
222 // If it's a bitcast involving vectors, make sure it has the same number
223 // of elements on both sides.
224 if (CI.getOpcode() != Instruction::BitCast ||
225 match(V: &CI, P: m_ElementWiseBitCast(Op: m_Value()))) {
226 if (Instruction *NV = FoldOpIntoSelect(Op&: CI, SI: Sel)) {
227 replaceAllDbgUsesWith(From&: *Sel, To&: *NV, DomPoint&: CI, DT);
228 return NV;
229 }
230 }
231 }
232 }
233
234 // If we are casting a PHI, then fold the cast into the PHI.
235 if (auto *PN = dyn_cast<PHINode>(Val: Src)) {
236 // Don't do this if it would create a PHI node with an illegal type from a
237 // legal type.
238 if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() ||
239 shouldChangeType(From: CI.getSrcTy(), To: CI.getType()))
240 if (Instruction *NV = foldOpIntoPhi(I&: CI, PN))
241 return NV;
242 }
243
244 // Canonicalize a unary shuffle after the cast if neither operation changes
245 // the size or element size of the input vector.
246 // TODO: We could allow size-changing ops if that doesn't harm codegen.
247 // cast (shuffle X, Mask) --> shuffle (cast X), Mask
248 Value *X;
249 ArrayRef<int> Mask;
250 if (match(V: Src, P: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: X), v2: m_Undef(), mask: m_Mask(Mask))))) {
251 // TODO: Allow scalable vectors?
252 auto *SrcTy = dyn_cast<FixedVectorType>(Val: X->getType());
253 auto *DestTy = dyn_cast<FixedVectorType>(Val: Ty);
254 if (SrcTy && DestTy &&
255 SrcTy->getNumElements() == DestTy->getNumElements() &&
256 SrcTy->getPrimitiveSizeInBits() == DestTy->getPrimitiveSizeInBits()) {
257 Value *CastX = Builder.CreateCast(Op: CI.getOpcode(), V: X, DestTy);
258 return new ShuffleVectorInst(CastX, Mask);
259 }
260 }
261
262 return nullptr;
263}
264
265namespace {
266
267/// Helper class for evaluating whether a value can be computed in a different
268/// type without changing its value. Used by cast simplification transforms.
269class TypeEvaluationHelper {
270public:
271 /// Return true if we can evaluate the specified expression tree as type Ty
272 /// instead of its larger type, and arrive with the same value.
273 /// This is used by code that tries to eliminate truncates.
274 [[nodiscard]] static bool canEvaluateTruncated(Value *V, Type *Ty,
275 InstCombinerImpl &IC,
276 Instruction *CxtI);
277
278 /// Determine if the specified value can be computed in the specified wider
279 /// type and produce the same low bits. If not, return false.
280 [[nodiscard]] static bool canEvaluateZExtd(Value *V, Type *Ty,
281 unsigned &BitsToClear,
282 InstCombinerImpl &IC,
283 Instruction *CxtI);
284
285 /// Return true if we can take the specified value and return it as type Ty
286 /// without inserting any new casts and without changing the value of the
287 /// common low bits.
288 [[nodiscard]] static bool canEvaluateSExtd(Value *V, Type *Ty);
289
290private:
291 /// Constants and extensions/truncates from the destination type are always
292 /// free to be evaluated in that type.
293 [[nodiscard]] static bool canAlwaysEvaluateInType(Value *V, Type *Ty);
294
295 /// Check if we traversed all the users of the multi-use values we've seen.
296 [[nodiscard]] bool allPendingVisited() const {
297 return llvm::all_of(Range: Pending,
298 P: [this](Value *V) { return Visited.contains(Val: V); });
299 }
300
301 /// A generic wrapper for canEvaluate* recursions to inject visitation
302 /// tracking and enforce correct multi-use value evaluations.
303 [[nodiscard]] bool
304 canEvaluate(Value *V, Type *Ty,
305 llvm::function_ref<bool(Value *, Type *Type)> Pred) {
306 if (canAlwaysEvaluateInType(V, Ty))
307 return true;
308
309 auto *I = dyn_cast<Instruction>(Val: V);
310
311 if (I == nullptr)
312 return false;
313
314 // We insert false by default to return false when we encounter user loops.
315 const auto [It, Inserted] = Visited.insert(KV: {V, false});
316
317 // There are three possible cases for us having information on this value
318 // in the Visited map:
319 // 1. We properly checked it and concluded that we can evaluate it (true)
320 // 2. We properly checked it and concluded that we can't (false)
321 // 3. We started to check it, but during the recursive traversal we came
322 // back to it.
323 //
324 // For cases 1 and 2, we can safely return the stored result. For case 3, we
325 // can potentially have a situation where we can evaluate recursive user
326 // chains, but that can be quite tricky to do properly and isntead, we
327 // return false.
328 //
329 // In any case, we should return whatever was there in the map to begin
330 // with.
331 if (!Inserted)
332 return It->getSecond();
333
334 // We can easily make a decision about single-user values whether they can
335 // be evaluated in a different type or not, we came from that user. This is
336 // not as simple for multi-user values.
337 //
338 // In general, we have the following case (inverted control-flow, users are
339 // at the top):
340 //
341 // Cast %A
342 // ____|
343 // /
344 // %A = Use %B, %C
345 // ________| |
346 // / |
347 // %B = Use %D |
348 // ________| |
349 // / |
350 // %D = Use %C |
351 // ________|___|
352 // /
353 // %C = ...
354 //
355 // In this case, when we check %A, %B and %D, we are confident that we can
356 // make the decision here and now, since we came from their only users.
357 //
358 // For %C, it is harder. We come there twice, and when we come the first
359 // time, it's hard to tell if we will visit the second user (technically
360 // it's not hard, but we might need a lot of repetitive checks with non-zero
361 // cost).
362 //
363 // In the case above, we are allowed to evaluate %C in different type
364 // because all of it users were part of the traversal.
365 //
366 // In the following case, however, we can't make this conclusion:
367 //
368 // Cast %A
369 // ____|
370 // /
371 // %A = Use %B, %C
372 // ________| |
373 // / |
374 // %B = Use %D |
375 // ________| |
376 // / |
377 // %D = Use %C |
378 // | |
379 // foo(%C) | | <- never traversing foo(%C)
380 // ________|___|
381 // /
382 // %C = ...
383 //
384 // In this case, we still can evaluate %C in a different type, but we'd need
385 // to create a copy of the original %C to be used in foo(%C). Such
386 // duplication might be not profitable.
387 //
388 // For this reason, we collect all users of the mult-user values and mark
389 // them as "pending" and defer this decision to the very end. When we are
390 // done and and ready to have a positive verdict, we should double-check all
391 // of the pending users and ensure that we visited them. allPendingVisited
392 // predicate checks exactly that.
393 if (!I->hasOneUse())
394 llvm::append_range(C&: Pending, R: I->users());
395
396 const bool Result = Pred(V, Ty);
397 // We have to set result this way and not via It because Pred is recursive
398 // and it is very likely that we grew Visited and invalidated It.
399 Visited[V] = Result;
400 return Result;
401 }
402
403 /// Filter out values that we can not evaluate in the destination type for
404 /// free.
405 [[nodiscard]] bool canNotEvaluateInType(Value *V, Type *Ty);
406
407 [[nodiscard]] bool canEvaluateTruncatedImpl(Value *V, Type *Ty,
408 InstCombinerImpl &IC,
409 Instruction *CxtI);
410 [[nodiscard]] bool canEvaluateTruncatedPred(Value *V, Type *Ty,
411 InstCombinerImpl &IC,
412 Instruction *CxtI);
413 [[nodiscard]] bool canEvaluateZExtdImpl(Value *V, Type *Ty,
414 unsigned &BitsToClear,
415 InstCombinerImpl &IC,
416 Instruction *CxtI);
417 [[nodiscard]] bool canEvaluateSExtdImpl(Value *V, Type *Ty);
418 [[nodiscard]] bool canEvaluateSExtdPred(Value *V, Type *Ty);
419
420 /// A bookkeeping map to memorize an already made decision for a traversed
421 /// value.
422 SmallDenseMap<Value *, bool, 8> Visited;
423
424 /// A list of pending values to check in the end.
425 SmallVector<Value *, 8> Pending;
426};
427
428} // anonymous namespace
429
430/// Constants and extensions/truncates from the destination type are always
431/// free to be evaluated in that type. This is a helper for canEvaluate*.
432bool TypeEvaluationHelper::canAlwaysEvaluateInType(Value *V, Type *Ty) {
433 if (isa<Constant>(Val: V))
434 return match(V, P: m_ImmConstant());
435
436 Value *X;
437 if ((match(V, P: m_ZExtOrSExt(Op: m_Value(V&: X))) || match(V, P: m_Trunc(Op: m_Value(V&: X)))) &&
438 X->getType() == Ty)
439 return true;
440
441 return false;
442}
443
444/// Filter out values that we can not evaluate in the destination type for free.
445/// This is a helper for canEvaluate*.
446bool TypeEvaluationHelper::canNotEvaluateInType(Value *V, Type *Ty) {
447 if (!isa<Instruction>(Val: V))
448 return true;
449 // We don't extend or shrink something that has multiple uses -- doing so
450 // would require duplicating the instruction which isn't profitable.
451 if (!V->hasOneUse())
452 return true;
453
454 return false;
455}
456
457/// Return true if we can evaluate the specified expression tree as type Ty
458/// instead of its larger type, and arrive with the same value.
459/// This is used by code that tries to eliminate truncates.
460///
461/// Ty will always be a type smaller than V. We should return true if trunc(V)
462/// can be computed by computing V in the smaller type. If V is an instruction,
463/// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
464/// makes sense if x and y can be efficiently truncated.
465///
466/// This function works on both vectors and scalars.
467///
468bool TypeEvaluationHelper::canEvaluateTruncated(Value *V, Type *Ty,
469 InstCombinerImpl &IC,
470 Instruction *CxtI) {
471 TypeEvaluationHelper TYH;
472 return TYH.canEvaluateTruncatedImpl(V, Ty, IC, CxtI) &&
473 // We need to check whether we visited all users of multi-user values,
474 // and we have to do it at the very end, outside of the recursion.
475 TYH.allPendingVisited();
476}
477
478bool TypeEvaluationHelper::canEvaluateTruncatedImpl(Value *V, Type *Ty,
479 InstCombinerImpl &IC,
480 Instruction *CxtI) {
481 return canEvaluate(V, Ty, Pred: [this, &IC, CxtI](Value *V, Type *Ty) {
482 return canEvaluateTruncatedPred(V, Ty, IC, CxtI);
483 });
484}
485
486bool TypeEvaluationHelper::canEvaluateTruncatedPred(Value *V, Type *Ty,
487 InstCombinerImpl &IC,
488 Instruction *CxtI) {
489 auto *I = cast<Instruction>(Val: V);
490 Type *OrigTy = V->getType();
491 switch (I->getOpcode()) {
492 case Instruction::Add:
493 case Instruction::Sub:
494 case Instruction::Mul:
495 case Instruction::And:
496 case Instruction::Or:
497 case Instruction::Xor:
498 // These operators can all arbitrarily be extended or truncated.
499 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
500 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
501
502 case Instruction::UDiv:
503 case Instruction::URem: {
504 // UDiv and URem can be truncated if all the truncated bits are zero.
505 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
506 uint32_t BitWidth = Ty->getScalarSizeInBits();
507 assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
508 APInt Mask = APInt::getBitsSetFrom(numBits: OrigBitWidth, loBit: BitWidth);
509 // Do not preserve the original context instruction. Simplifying div/rem
510 // based on later context may introduce a trap.
511 if (IC.MaskedValueIsZero(V: I->getOperand(i: 0), Mask, CxtI: I) &&
512 IC.MaskedValueIsZero(V: I->getOperand(i: 1), Mask, CxtI: I)) {
513 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
514 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
515 }
516 break;
517 }
518 case Instruction::Shl: {
519 // If we are truncating the result of this SHL, and if it's a shift of an
520 // inrange amount, we can always perform a SHL in a smaller type.
521 uint32_t BitWidth = Ty->getScalarSizeInBits();
522 KnownBits AmtKnownBits =
523 llvm::computeKnownBits(V: I->getOperand(i: 1), DL: IC.getDataLayout());
524 if (AmtKnownBits.getMaxValue().ult(RHS: BitWidth))
525 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
526 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
527 break;
528 }
529 case Instruction::LShr: {
530 // If this is a truncate of a logical shr, we can truncate it to a smaller
531 // lshr iff we know that the bits we would otherwise be shifting in are
532 // already zeros.
533 // TODO: It is enough to check that the bits we would be shifting in are
534 // zero - use AmtKnownBits.getMaxValue().
535 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
536 uint32_t BitWidth = Ty->getScalarSizeInBits();
537 KnownBits AmtKnownBits = IC.computeKnownBits(V: I->getOperand(i: 1), CxtI);
538 APInt MaxShiftAmt = AmtKnownBits.getMaxValue();
539 APInt ShiftedBits = APInt::getBitsSetFrom(numBits: OrigBitWidth, loBit: BitWidth);
540 if (MaxShiftAmt.ult(RHS: BitWidth)) {
541 // If the only user is a trunc then we can narrow the shift if any new
542 // MSBs are not going to be used.
543 if (auto *Trunc = dyn_cast<TruncInst>(Val: V->user_back())) {
544 auto DemandedBits = Trunc->getType()->getScalarSizeInBits();
545 if ((MaxShiftAmt + DemandedBits).ule(RHS: BitWidth))
546 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
547 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
548 }
549 if (IC.MaskedValueIsZero(V: I->getOperand(i: 0), Mask: ShiftedBits, CxtI))
550 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
551 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
552 }
553 break;
554 }
555 case Instruction::AShr: {
556 // If this is a truncate of an arithmetic shr, we can truncate it to a
557 // smaller ashr iff we know that all the bits from the sign bit of the
558 // original type and the sign bit of the truncate type are similar.
559 // TODO: It is enough to check that the bits we would be shifting in are
560 // similar to sign bit of the truncate type.
561 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
562 uint32_t BitWidth = Ty->getScalarSizeInBits();
563 KnownBits AmtKnownBits =
564 llvm::computeKnownBits(V: I->getOperand(i: 1), DL: IC.getDataLayout());
565 unsigned ShiftedBits = OrigBitWidth - BitWidth;
566 if (AmtKnownBits.getMaxValue().ult(RHS: BitWidth) &&
567 ShiftedBits < IC.ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI))
568 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
569 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
570 break;
571 }
572 case Instruction::Trunc:
573 // trunc(trunc(x)) -> trunc(x)
574 return true;
575 case Instruction::ZExt:
576 case Instruction::SExt:
577 // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
578 // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
579 return true;
580 case Instruction::Select: {
581 SelectInst *SI = cast<SelectInst>(Val: I);
582 return canEvaluateTruncatedImpl(V: SI->getTrueValue(), Ty, IC, CxtI) &&
583 canEvaluateTruncatedImpl(V: SI->getFalseValue(), Ty, IC, CxtI);
584 }
585 case Instruction::PHI: {
586 // We can change a phi if we can change all operands. Note that we never
587 // get into trouble with cyclic PHIs here because canEvaluate handles use
588 // chain loops.
589 PHINode *PN = cast<PHINode>(Val: I);
590 return llvm::all_of(
591 Range: PN->incoming_values(), P: [this, Ty, &IC, CxtI](Value *IncValue) {
592 return canEvaluateTruncatedImpl(V: IncValue, Ty, IC, CxtI);
593 });
594 }
595 case Instruction::FPToUI:
596 case Instruction::FPToSI: {
597 // If the integer type can hold the max FP value, it is safe to cast
598 // directly to that type. Otherwise, we may create poison via overflow
599 // that did not exist in the original code.
600 Type *InputTy = I->getOperand(i: 0)->getType()->getScalarType();
601 const fltSemantics &Semantics = InputTy->getFltSemantics();
602 uint32_t MinBitWidth = APFloatBase::semanticsIntSizeInBits(
603 Semantics, I->getOpcode() == Instruction::FPToSI);
604 return Ty->getScalarSizeInBits() >= MinBitWidth;
605 }
606 case Instruction::ShuffleVector:
607 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
608 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
609
610 default:
611 // TODO: Can handle more cases here.
612 break;
613 }
614
615 return false;
616}
617
618/// Given a vector that is bitcast to an integer, optionally logically
619/// right-shifted, and truncated, convert it to an extractelement.
620/// Example (big endian):
621/// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32
622/// --->
623/// extractelement <4 x i32> %X, 1
624static Instruction *foldVecTruncToExtElt(TruncInst &Trunc,
625 InstCombinerImpl &IC) {
626 Value *TruncOp = Trunc.getOperand(i_nocapture: 0);
627 Type *DestType = Trunc.getType();
628 if (!TruncOp->hasOneUse() || !isa<IntegerType>(Val: DestType))
629 return nullptr;
630
631 Value *VecInput = nullptr;
632 ConstantInt *ShiftVal = nullptr;
633 if (!match(V: TruncOp, P: m_CombineOr(L: m_BitCast(Op: m_Value(V&: VecInput)),
634 R: m_LShr(L: m_BitCast(Op: m_Value(V&: VecInput)),
635 R: m_ConstantInt(CI&: ShiftVal)))) ||
636 !isa<VectorType>(Val: VecInput->getType()))
637 return nullptr;
638
639 VectorType *VecType = cast<VectorType>(Val: VecInput->getType());
640 unsigned VecWidth = VecType->getPrimitiveSizeInBits();
641 unsigned DestWidth = DestType->getPrimitiveSizeInBits();
642 unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0;
643
644 if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0))
645 return nullptr;
646
647 // If the element type of the vector doesn't match the result type,
648 // bitcast it to a vector type that we can extract from.
649 unsigned NumVecElts = VecWidth / DestWidth;
650 if (VecType->getElementType() != DestType) {
651 VecType = FixedVectorType::get(ElementType: DestType, NumElts: NumVecElts);
652 VecInput = IC.Builder.CreateBitCast(V: VecInput, DestTy: VecType, Name: "bc");
653 }
654
655 unsigned Elt = ShiftAmount / DestWidth;
656 if (IC.getDataLayout().isBigEndian())
657 Elt = NumVecElts - 1 - Elt;
658
659 return ExtractElementInst::Create(Vec: VecInput, Idx: IC.Builder.getInt32(C: Elt));
660}
661
662/// Whenever an element is extracted from a vector, optionally shifted down, and
663/// then truncated, canonicalize by converting it to a bitcast followed by an
664/// extractelement.
665///
666/// Examples (little endian):
667/// trunc (extractelement <4 x i64> %X, 0) to i32
668/// --->
669/// extractelement <8 x i32> (bitcast <4 x i64> %X to <8 x i32>), i32 0
670///
671/// trunc (lshr (extractelement <4 x i32> %X, 0), 8) to i8
672/// --->
673/// extractelement <16 x i8> (bitcast <4 x i32> %X to <16 x i8>), i32 1
674static Instruction *foldVecExtTruncToExtElt(TruncInst &Trunc,
675 InstCombinerImpl &IC) {
676 Value *Src = Trunc.getOperand(i_nocapture: 0);
677 Type *SrcType = Src->getType();
678 Type *DstType = Trunc.getType();
679
680 // Only attempt this if we have simple aliasing of the vector elements.
681 // A badly fit destination size would result in an invalid cast.
682 unsigned SrcBits = SrcType->getScalarSizeInBits();
683 unsigned DstBits = DstType->getScalarSizeInBits();
684 unsigned TruncRatio = SrcBits / DstBits;
685 if ((SrcBits % DstBits) != 0)
686 return nullptr;
687
688 Value *VecOp;
689 ConstantInt *Cst;
690 const APInt *ShiftAmount = nullptr;
691 if (!match(V: Src, P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_ConstantInt(CI&: Cst)))) &&
692 !match(V: Src,
693 P: m_OneUse(SubPattern: m_LShr(L: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_ConstantInt(CI&: Cst)),
694 R: m_APInt(Res&: ShiftAmount)))))
695 return nullptr;
696
697 auto *VecOpTy = cast<VectorType>(Val: VecOp->getType());
698 auto VecElts = VecOpTy->getElementCount();
699
700 uint64_t BitCastNumElts = VecElts.getKnownMinValue() * TruncRatio;
701 // Make sure we don't overflow in the calculation of the new index.
702 // (VecOpIdx + 1) * TruncRatio should not overflow.
703 if (Cst->uge(Num: std::numeric_limits<uint64_t>::max() / TruncRatio))
704 return nullptr;
705 uint64_t VecOpIdx = Cst->getZExtValue();
706 uint64_t NewIdx = IC.getDataLayout().isBigEndian()
707 ? (VecOpIdx + 1) * TruncRatio - 1
708 : VecOpIdx * TruncRatio;
709
710 // Adjust index by the whole number of truncated elements.
711 if (ShiftAmount) {
712 // Check shift amount is in range and shifts a whole number of truncated
713 // elements.
714 if (ShiftAmount->uge(RHS: SrcBits) || ShiftAmount->urem(RHS: DstBits) != 0)
715 return nullptr;
716
717 uint64_t IdxOfs = ShiftAmount->udiv(RHS: DstBits).getZExtValue();
718 // IdxOfs is guaranteed to be less than TruncRatio, so we won't overflow in
719 // the adjustment.
720 assert(IdxOfs < TruncRatio &&
721 "IdxOfs is expected to be less than TruncRatio.");
722 NewIdx = IC.getDataLayout().isBigEndian() ? (NewIdx - IdxOfs)
723 : (NewIdx + IdxOfs);
724 }
725
726 assert(BitCastNumElts <= std::numeric_limits<uint32_t>::max() &&
727 "overflow 32-bits");
728
729 auto *BitCastTo =
730 VectorType::get(ElementType: DstType, NumElements: BitCastNumElts, Scalable: VecElts.isScalable());
731 Value *BitCast = IC.Builder.CreateBitCast(V: VecOp, DestTy: BitCastTo);
732 return ExtractElementInst::Create(Vec: BitCast, Idx: IC.Builder.getInt64(C: NewIdx));
733}
734
735/// Funnel/Rotate left/right may occur in a wider type than necessary because of
736/// type promotion rules. Try to narrow the inputs and convert to funnel shift.
737Instruction *InstCombinerImpl::narrowFunnelShift(TruncInst &Trunc) {
738 assert((isa<VectorType>(Trunc.getSrcTy()) ||
739 shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) &&
740 "Don't narrow to an illegal scalar type");
741
742 // Bail out on strange types. It is possible to handle some of these patterns
743 // even with non-power-of-2 sizes, but it is not a likely scenario.
744 Type *DestTy = Trunc.getType();
745 unsigned NarrowWidth = DestTy->getScalarSizeInBits();
746 unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
747 if (!isPowerOf2_32(Value: NarrowWidth))
748 return nullptr;
749
750 // First, find an or'd pair of opposite shifts:
751 // trunc (or (lshr ShVal0, ShAmt0), (shl ShVal1, ShAmt1))
752 BinaryOperator *Or0, *Or1;
753 if (!match(V: Trunc.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_Or(L: m_BinOp(I&: Or0), R: m_BinOp(I&: Or1)))))
754 return nullptr;
755
756 Value *ShVal0, *ShVal1, *ShAmt0, *ShAmt1;
757 if (!match(V: Or0, P: m_OneUse(SubPattern: m_LogicalShift(L: m_Value(V&: ShVal0), R: m_Value(V&: ShAmt0)))) ||
758 !match(V: Or1, P: m_OneUse(SubPattern: m_LogicalShift(L: m_Value(V&: ShVal1), R: m_Value(V&: ShAmt1)))) ||
759 Or0->getOpcode() == Or1->getOpcode())
760 return nullptr;
761
762 // Canonicalize to or(shl(ShVal0, ShAmt0), lshr(ShVal1, ShAmt1)).
763 if (Or0->getOpcode() == BinaryOperator::LShr) {
764 std::swap(a&: Or0, b&: Or1);
765 std::swap(a&: ShVal0, b&: ShVal1);
766 std::swap(a&: ShAmt0, b&: ShAmt1);
767 }
768 assert(Or0->getOpcode() == BinaryOperator::Shl &&
769 Or1->getOpcode() == BinaryOperator::LShr &&
770 "Illegal or(shift,shift) pair");
771
772 // Match the shift amount operands for a funnel/rotate pattern. This always
773 // matches a subtraction on the R operand.
774 auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
775 // The shift amounts may add up to the narrow bit width:
776 // (shl ShVal0, L) | (lshr ShVal1, Width - L)
777 // If this is a funnel shift (different operands are shifted), then the
778 // shift amount can not over-shift (create poison) in the narrow type.
779 unsigned MaxShiftAmountWidth = Log2_32(Value: NarrowWidth);
780 APInt HiBitMask = ~APInt::getLowBitsSet(numBits: WideWidth, loBitsSet: MaxShiftAmountWidth);
781 if (ShVal0 == ShVal1 || MaskedValueIsZero(V: L, Mask: HiBitMask))
782 if (match(V: R, P: m_OneUse(SubPattern: m_Sub(L: m_SpecificInt(V: Width), R: m_Specific(V: L)))))
783 return L;
784
785 // The following patterns currently only work for rotation patterns.
786 // TODO: Add more general funnel-shift compatible patterns.
787 if (ShVal0 != ShVal1)
788 return nullptr;
789
790 // The shift amount may be masked with negation:
791 // (shl ShVal0, (X & (Width - 1))) | (lshr ShVal1, ((-X) & (Width - 1)))
792 Value *X;
793 unsigned Mask = Width - 1;
794 if (match(V: L, P: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: Mask))) &&
795 match(V: R, P: m_And(L: m_Neg(V: m_Specific(V: X)), R: m_SpecificInt(V: Mask))))
796 return X;
797
798 // Same as above, but the shift amount may be extended after masking:
799 if (match(V: L, P: m_ZExt(Op: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: Mask)))) &&
800 match(V: R, P: m_ZExt(Op: m_And(L: m_Neg(V: m_Specific(V: X)), R: m_SpecificInt(V: Mask)))))
801 return X;
802
803 return nullptr;
804 };
805
806 Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth);
807 bool IsFshl = true; // Sub on LSHR.
808 if (!ShAmt) {
809 ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth);
810 IsFshl = false; // Sub on SHL.
811 }
812 if (!ShAmt)
813 return nullptr;
814
815 // The right-shifted value must have high zeros in the wide type (for example
816 // from 'zext', 'and' or 'shift'). High bits of the left-shifted value are
817 // truncated, so those do not matter.
818 APInt HiBitMask = APInt::getHighBitsSet(numBits: WideWidth, hiBitsSet: WideWidth - NarrowWidth);
819 if (!MaskedValueIsZero(V: ShVal1, Mask: HiBitMask, CxtI: &Trunc))
820 return nullptr;
821
822 // Adjust the width of ShAmt for narrowed funnel shift operation:
823 // - Zero-extend if ShAmt is narrower than the destination type.
824 // - Truncate if ShAmt is wider, discarding non-significant high-order bits.
825 // This prepares ShAmt for llvm.fshl.i8(trunc(ShVal), trunc(ShVal),
826 // zext/trunc(ShAmt)).
827 Value *NarrowShAmt = Builder.CreateZExtOrTrunc(V: ShAmt, DestTy);
828
829 Value *X, *Y;
830 X = Y = Builder.CreateTrunc(V: ShVal0, DestTy);
831 if (ShVal0 != ShVal1)
832 Y = Builder.CreateTrunc(V: ShVal1, DestTy);
833 Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
834 Function *F =
835 Intrinsic::getOrInsertDeclaration(M: Trunc.getModule(), id: IID, Tys: DestTy);
836 return CallInst::Create(Func: F, Args: {X, Y, NarrowShAmt});
837}
838
839/// Try to narrow the width of math or bitwise logic instructions by pulling a
840/// truncate ahead of binary operators.
841Instruction *InstCombinerImpl::narrowBinOp(TruncInst &Trunc) {
842 Type *SrcTy = Trunc.getSrcTy();
843 Type *DestTy = Trunc.getType();
844 unsigned SrcWidth = SrcTy->getScalarSizeInBits();
845 unsigned DestWidth = DestTy->getScalarSizeInBits();
846
847 if (!isa<VectorType>(Val: SrcTy) && !shouldChangeType(From: SrcTy, To: DestTy))
848 return nullptr;
849
850 BinaryOperator *BinOp;
851 if (!match(V: Trunc.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BinOp))))
852 return nullptr;
853
854 Value *BinOp0 = BinOp->getOperand(i_nocapture: 0);
855 Value *BinOp1 = BinOp->getOperand(i_nocapture: 1);
856 switch (BinOp->getOpcode()) {
857 case Instruction::And:
858 case Instruction::Or:
859 case Instruction::Xor:
860 case Instruction::Add:
861 case Instruction::Sub:
862 case Instruction::Mul: {
863 Constant *C;
864 if (match(V: BinOp0, P: m_Constant(C))) {
865 // trunc (binop C, X) --> binop (trunc C', X)
866 Constant *NarrowC = ConstantExpr::getTrunc(C, Ty: DestTy);
867 Value *TruncX = Builder.CreateTrunc(V: BinOp1, DestTy);
868 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: NarrowC, S2: TruncX);
869 }
870 if (match(V: BinOp1, P: m_Constant(C))) {
871 // trunc (binop X, C) --> binop (trunc X, C')
872 Constant *NarrowC = ConstantExpr::getTrunc(C, Ty: DestTy);
873 Value *TruncX = Builder.CreateTrunc(V: BinOp0, DestTy);
874 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: TruncX, S2: NarrowC);
875 }
876 Value *X;
877 if (match(V: BinOp0, P: m_ZExtOrSExt(Op: m_Value(V&: X))) && X->getType() == DestTy) {
878 // trunc (binop (ext X), Y) --> binop X, (trunc Y)
879 Value *NarrowOp1 = Builder.CreateTrunc(V: BinOp1, DestTy);
880 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: X, S2: NarrowOp1);
881 }
882 if (match(V: BinOp1, P: m_ZExtOrSExt(Op: m_Value(V&: X))) && X->getType() == DestTy) {
883 // trunc (binop Y, (ext X)) --> binop (trunc Y), X
884 Value *NarrowOp0 = Builder.CreateTrunc(V: BinOp0, DestTy);
885 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: NarrowOp0, S2: X);
886 }
887 break;
888 }
889 case Instruction::LShr:
890 case Instruction::AShr: {
891 // trunc (*shr (trunc A), C) --> trunc(*shr A, C)
892 Value *A;
893 Constant *C;
894 if (match(V: BinOp0, P: m_Trunc(Op: m_Value(V&: A))) && match(V: BinOp1, P: m_Constant(C))) {
895 unsigned MaxShiftAmt = SrcWidth - DestWidth;
896 // If the shift is small enough, all zero/sign bits created by the shift
897 // are removed by the trunc.
898 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
899 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
900 auto *OldShift = cast<Instruction>(Val: Trunc.getOperand(i_nocapture: 0));
901 bool IsExact = OldShift->isExact();
902 if (Constant *ShAmt = ConstantFoldIntegerCast(C, DestTy: A->getType(),
903 /*IsSigned*/ true, DL)) {
904 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
905 Value *Shift =
906 OldShift->getOpcode() == Instruction::AShr
907 ? Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: OldShift->getName(), isExact: IsExact)
908 : Builder.CreateLShr(LHS: A, RHS: ShAmt, Name: OldShift->getName(), isExact: IsExact);
909 return CastInst::CreateTruncOrBitCast(S: Shift, Ty: DestTy);
910 }
911 }
912 }
913 break;
914 }
915 default: break;
916 }
917
918 if (Instruction *NarrowOr = narrowFunnelShift(Trunc))
919 return NarrowOr;
920
921 return nullptr;
922}
923
924/// Try to narrow the width of a splat shuffle. This could be generalized to any
925/// shuffle with a constant operand, but we limit the transform to avoid
926/// creating a shuffle type that targets may not be able to lower effectively.
927static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
928 InstCombiner::BuilderTy &Builder) {
929 auto *Shuf = dyn_cast<ShuffleVectorInst>(Val: Trunc.getOperand(i_nocapture: 0));
930 if (Shuf && Shuf->hasOneUse() && match(V: Shuf->getOperand(i_nocapture: 1), P: m_Undef()) &&
931 all_equal(Range: Shuf->getShuffleMask()) &&
932 ElementCount::isKnownGE(LHS: Shuf->getType()->getElementCount(),
933 RHS: cast<VectorType>(Val: Shuf->getOperand(i_nocapture: 0)->getType())
934 ->getElementCount())) {
935 // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Poison, SplatMask
936 // trunc (shuf X, Poison, SplatMask) --> shuf (trunc X), Poison, SplatMask
937 Type *NewTruncTy = Shuf->getOperand(i_nocapture: 0)->getType()->getWithNewType(
938 EltTy: Trunc.getType()->getScalarType());
939 Value *NarrowOp = Builder.CreateTrunc(V: Shuf->getOperand(i_nocapture: 0), DestTy: NewTruncTy);
940 return new ShuffleVectorInst(NarrowOp, Shuf->getShuffleMask());
941 }
942
943 return nullptr;
944}
945
946/// Try to narrow the width of an insert element. This could be generalized for
947/// any vector constant, but we limit the transform to insertion into undef to
948/// avoid potential backend problems from unsupported insertion widths. This
949/// could also be extended to handle the case of inserting a scalar constant
950/// into a vector variable.
951static Instruction *shrinkInsertElt(CastInst &Trunc,
952 InstCombiner::BuilderTy &Builder) {
953 Instruction::CastOps Opcode = Trunc.getOpcode();
954 assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
955 "Unexpected instruction for shrinking");
956
957 auto *InsElt = dyn_cast<InsertElementInst>(Val: Trunc.getOperand(i_nocapture: 0));
958 if (!InsElt || !InsElt->hasOneUse())
959 return nullptr;
960
961 Type *DestTy = Trunc.getType();
962 Type *DestScalarTy = DestTy->getScalarType();
963 Value *VecOp = InsElt->getOperand(i_nocapture: 0);
964 Value *ScalarOp = InsElt->getOperand(i_nocapture: 1);
965 Value *Index = InsElt->getOperand(i_nocapture: 2);
966
967 if (match(V: VecOp, P: m_Undef())) {
968 // trunc (inselt undef, X, Index) --> inselt undef, (trunc X), Index
969 // fptrunc (inselt undef, X, Index) --> inselt undef, (fptrunc X), Index
970 UndefValue *NarrowUndef = UndefValue::get(T: DestTy);
971 Value *NarrowOp = Builder.CreateCast(Op: Opcode, V: ScalarOp, DestTy: DestScalarTy);
972 return InsertElementInst::Create(Vec: NarrowUndef, NewElt: NarrowOp, Idx: Index);
973 }
974
975 return nullptr;
976}
977
978Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
979 if (Instruction *Result = commonCastTransforms(CI&: Trunc))
980 return Result;
981
982 Value *Src = Trunc.getOperand(i_nocapture: 0);
983 Type *DestTy = Trunc.getType(), *SrcTy = Src->getType();
984 unsigned DestWidth = DestTy->getScalarSizeInBits();
985 unsigned SrcWidth = SrcTy->getScalarSizeInBits();
986
987 // Attempt to truncate the entire input expression tree to the destination
988 // type. Only do this if the dest type is a simple type, don't convert the
989 // expression tree to something weird like i93 unless the source is also
990 // strange.
991 if ((DestTy->isVectorTy() || shouldChangeType(From: SrcTy, To: DestTy)) &&
992 TypeEvaluationHelper::canEvaluateTruncated(V: Src, Ty: DestTy, IC&: *this, CxtI: &Trunc)) {
993
994 // If this cast is a truncate, evaluting in a different type always
995 // eliminates the cast, so it is always a win.
996 LLVM_DEBUG(
997 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
998 " to avoid cast: "
999 << Trunc << '\n');
1000 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: false);
1001 assert(Res->getType() == DestTy);
1002 return replaceInstUsesWith(I&: Trunc, V: Res);
1003 }
1004
1005 // For integer types, check if we can shorten the entire input expression to
1006 // DestWidth * 2, which won't allow removing the truncate, but reducing the
1007 // width may enable further optimizations, e.g. allowing for larger
1008 // vectorization factors.
1009 if (auto *DestITy = dyn_cast<IntegerType>(Val: DestTy)) {
1010 if (DestWidth * 2 < SrcWidth) {
1011 auto *NewDestTy = DestITy->getExtendedType();
1012 if (shouldChangeType(From: SrcTy, To: NewDestTy) &&
1013 TypeEvaluationHelper::canEvaluateTruncated(V: Src, Ty: NewDestTy, IC&: *this,
1014 CxtI: &Trunc)) {
1015 LLVM_DEBUG(
1016 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1017 " to reduce the width of operand of"
1018 << Trunc << '\n');
1019 Value *Res = EvaluateInDifferentType(V: Src, Ty: NewDestTy, isSigned: false);
1020 return new TruncInst(Res, DestTy);
1021 }
1022 }
1023 }
1024
1025 // See if we can simplify any instructions used by the input whose sole
1026 // purpose is to compute bits we don't care about.
1027 if (SimplifyDemandedInstructionBits(Inst&: Trunc))
1028 return &Trunc;
1029
1030 if (DestWidth == 1) {
1031 Value *Zero = Constant::getNullValue(Ty: SrcTy);
1032
1033 Value *X;
1034 const APInt *C1;
1035 Constant *C2;
1036 if (match(V: Src, P: m_OneUse(SubPattern: m_Shr(L: m_Shl(L: m_Power2(V&: C1), R: m_Value(V&: X)),
1037 R: m_ImmConstant(C&: C2))))) {
1038 // trunc ((C1 << X) >> C2) to i1 --> X == (C2-cttz(C1)), where C1 is pow2
1039 Constant *Log2C1 = ConstantInt::get(Ty: SrcTy, V: C1->exactLogBase2());
1040 Constant *CmpC = ConstantExpr::getSub(C1: C2, C2: Log2C1);
1041 return new ICmpInst(ICmpInst::ICMP_EQ, X, CmpC);
1042 }
1043
1044 if (match(V: Src, P: m_Shr(L: m_Value(V&: X), R: m_SpecificInt(V: SrcWidth - 1)))) {
1045 // trunc (ashr X, BW-1) to i1 --> icmp slt X, 0
1046 // trunc (lshr X, BW-1) to i1 --> icmp slt X, 0
1047 return new ICmpInst(ICmpInst::ICMP_SLT, X, Zero);
1048 }
1049
1050 Constant *C;
1051 if (match(V: Src, P: m_OneUse(SubPattern: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C))))) {
1052 // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
1053 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1054 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1055 Value *And = Builder.CreateAnd(LHS: X, RHS: MaskC);
1056 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1057 }
1058 if (match(V: Src, P: m_OneUse(SubPattern: m_c_Or(L: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C)),
1059 R: m_Deferred(V: X))))) {
1060 // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
1061 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1062 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1063 Value *And = Builder.CreateAnd(LHS: X, RHS: Builder.CreateOr(LHS: MaskC, RHS: One));
1064 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1065 }
1066
1067 {
1068 const APInt *C;
1069 if (match(V: Src, P: m_Shl(L: m_APInt(Res&: C), R: m_Value(V&: X))) && (*C)[0] == 1) {
1070 // trunc (C << X) to i1 --> X == 0, where C is odd
1071 return new ICmpInst(ICmpInst::Predicate::ICMP_EQ, X, Zero);
1072 }
1073 }
1074
1075 if (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) {
1076 Value *X, *Y;
1077 if (match(V: Src, P: m_Xor(L: m_Value(V&: X), R: m_Value(V&: Y))))
1078 return new ICmpInst(ICmpInst::ICMP_NE, X, Y);
1079 }
1080 }
1081
1082 Value *A, *B;
1083 Constant *C;
1084 if (match(V: Src, P: m_LShr(L: m_SExt(Op: m_Value(V&: A)), R: m_Constant(C)))) {
1085 unsigned AWidth = A->getType()->getScalarSizeInBits();
1086 unsigned MaxShiftAmt = SrcWidth - std::max(a: DestWidth, b: AWidth);
1087 auto *OldSh = cast<Instruction>(Val: Src);
1088 bool IsExact = OldSh->isExact();
1089
1090 // If the shift is small enough, all zero bits created by the shift are
1091 // removed by the trunc.
1092 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
1093 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
1094 auto GetNewShAmt = [&](unsigned Width) {
1095 Constant *MaxAmt = ConstantInt::get(Ty: SrcTy, V: Width - 1, IsSigned: false);
1096 Constant *Cmp =
1097 ConstantFoldCompareInstOperands(Predicate: ICmpInst::ICMP_ULT, LHS: C, RHS: MaxAmt, DL);
1098 Constant *ShAmt = ConstantFoldSelectInstruction(Cond: Cmp, V1: C, V2: MaxAmt);
1099 return ConstantFoldCastOperand(Opcode: Instruction::Trunc, C: ShAmt, DestTy: A->getType(),
1100 DL);
1101 };
1102
1103 // trunc (lshr (sext A), C) --> ashr A, C
1104 if (A->getType() == DestTy) {
1105 Constant *ShAmt = GetNewShAmt(DestWidth);
1106 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
1107 return IsExact ? BinaryOperator::CreateExactAShr(V1: A, V2: ShAmt)
1108 : BinaryOperator::CreateAShr(V1: A, V2: ShAmt);
1109 }
1110 // The types are mismatched, so create a cast after shifting:
1111 // trunc (lshr (sext A), C) --> sext/trunc (ashr A, C)
1112 if (Src->hasOneUse()) {
1113 Constant *ShAmt = GetNewShAmt(AWidth);
1114 Value *Shift = Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: "", isExact: IsExact);
1115 return CastInst::CreateIntegerCast(S: Shift, Ty: DestTy, isSigned: true);
1116 }
1117 }
1118 // TODO: Mask high bits with 'and'.
1119 }
1120
1121 if (Instruction *I = narrowBinOp(Trunc))
1122 return I;
1123
1124 if (Instruction *I = shrinkSplatShuffle(Trunc, Builder))
1125 return I;
1126
1127 if (Instruction *I = shrinkInsertElt(Trunc, Builder))
1128 return I;
1129
1130 if (Src->hasOneUse() &&
1131 (isa<VectorType>(Val: SrcTy) || shouldChangeType(From: SrcTy, To: DestTy))) {
1132 // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
1133 // dest type is native and cst < dest size.
1134 if (match(V: Src, P: m_Shl(L: m_Value(V&: A), R: m_Constant(C))) &&
1135 !match(V: A, P: m_Shr(L: m_Value(), R: m_Constant()))) {
1136 // Skip shifts of shift by constants. It undoes a combine in
1137 // FoldShiftByConstant and is the extend in reg pattern.
1138 APInt Threshold = APInt(C->getType()->getScalarSizeInBits(), DestWidth);
1139 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULT, Threshold))) {
1140 Value *NewTrunc = Builder.CreateTrunc(V: A, DestTy, Name: A->getName() + ".tr");
1141 return BinaryOperator::Create(Op: Instruction::Shl, S1: NewTrunc,
1142 S2: ConstantExpr::getTrunc(C, Ty: DestTy));
1143 }
1144 }
1145 }
1146
1147 if (Instruction *I = foldVecTruncToExtElt(Trunc, IC&: *this))
1148 return I;
1149
1150 if (Instruction *I = foldVecExtTruncToExtElt(Trunc, IC&: *this))
1151 return I;
1152
1153 // trunc (ctlz_i32(zext(A), B) --> add(ctlz_i16(A, B), C)
1154 if (match(V: Src, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ctlz>(Op0: m_ZExt(Op: m_Value(V&: A)),
1155 Op1: m_Value(V&: B))))) {
1156 unsigned AWidth = A->getType()->getScalarSizeInBits();
1157 if (AWidth == DestWidth && AWidth > Log2_32(Value: SrcWidth)) {
1158 Value *WidthDiff = ConstantInt::get(Ty: A->getType(), V: SrcWidth - AWidth);
1159 Value *NarrowCtlz =
1160 Builder.CreateIntrinsic(ID: Intrinsic::ctlz, Types: {Trunc.getType()}, Args: {A, B});
1161 return BinaryOperator::CreateAdd(V1: NarrowCtlz, V2: WidthDiff);
1162 }
1163 }
1164
1165 if (match(V: Src, P: m_VScale())) {
1166 if (Trunc.getFunction() &&
1167 Trunc.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1168 Attribute Attr =
1169 Trunc.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1170 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
1171 if (Log2_32(Value: *MaxVScale) < DestWidth)
1172 return replaceInstUsesWith(I&: Trunc, V: Builder.CreateVScale(Ty: DestTy));
1173 }
1174 }
1175
1176 if (DestWidth == 1 &&
1177 (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) &&
1178 isKnownNonZero(V: Src, Q: SQ.getWithInstruction(I: &Trunc)))
1179 return replaceInstUsesWith(I&: Trunc, V: ConstantInt::getTrue(Ty: DestTy));
1180
1181 bool Changed = false;
1182 if (!Trunc.hasNoSignedWrap() &&
1183 ComputeMaxSignificantBits(Op: Src, CxtI: &Trunc) <= DestWidth) {
1184 Trunc.setHasNoSignedWrap(true);
1185 Changed = true;
1186 }
1187 if (!Trunc.hasNoUnsignedWrap() &&
1188 MaskedValueIsZero(V: Src, Mask: APInt::getBitsSetFrom(numBits: SrcWidth, loBit: DestWidth),
1189 CxtI: &Trunc)) {
1190 Trunc.setHasNoUnsignedWrap(true);
1191 Changed = true;
1192 }
1193
1194 const APInt *C1;
1195 Value *V1;
1196 // OP = { lshr, ashr }
1197 // trunc ( OP i8 C1, V1) to i1 -> icmp eq V1, log_2(C1) iff C1 is power of 2
1198 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_Power2(V&: C1), R: m_Value(V&: V1)))) {
1199 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1200 return new ICmpInst(ICmpInst::ICMP_EQ, V1, Right);
1201 }
1202
1203 // OP = { lshr, ashr }
1204 // trunc ( OP i8 C1, V1) to i1 -> icmp ult V1, log_2(C1 + 1) iff (C1 + 1) is
1205 // power of 2
1206 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_LowBitMask(V&: C1), R: m_Value(V&: V1)))) {
1207 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_one());
1208 return new ICmpInst(ICmpInst::ICMP_ULT, V1, Right);
1209 }
1210
1211 // OP = { lshr, ashr }
1212 // trunc ( OP i8 C1, V1) to i1 -> icmp ugt V1, cttz(C1) - 1 iff (C1) is
1213 // negative power of 2
1214 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_NegatedPower2(V&: C1), R: m_Value(V&: V1)))) {
1215 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1216 return new ICmpInst(ICmpInst::ICMP_UGE, V1, Right);
1217 }
1218
1219 return Changed ? &Trunc : nullptr;
1220}
1221
1222Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp,
1223 ZExtInst &Zext) {
1224 // If we are just checking for a icmp eq of a single bit and zext'ing it
1225 // to an integer, then shift the bit to the appropriate place and then
1226 // cast to integer to avoid the comparison.
1227
1228 // FIXME: This set of transforms does not check for extra uses and/or creates
1229 // an extra instruction (an optional final cast is not included
1230 // in the transform comments). We may also want to favor icmp over
1231 // shifts in cases of equal instructions because icmp has better
1232 // analysis in general (invert the transform).
1233
1234 const APInt *Op1CV;
1235 if (match(V: Cmp->getOperand(i_nocapture: 1), P: m_APInt(Res&: Op1CV))) {
1236
1237 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
1238 if (Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) {
1239 Value *In = Cmp->getOperand(i_nocapture: 0);
1240 Value *Sh = ConstantInt::get(Ty: In->getType(),
1241 V: In->getType()->getScalarSizeInBits() - 1);
1242 In = Builder.CreateLShr(LHS: In, RHS: Sh, Name: In->getName() + ".lobit");
1243 if (In->getType() != Zext.getType())
1244 In = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false /*ZExt*/);
1245
1246 return replaceInstUsesWith(I&: Zext, V: In);
1247 }
1248
1249 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
1250 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
1251 // zext (X != 0) to i32 --> X iff X has only the low bit set.
1252 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
1253
1254 if (Op1CV->isZero() && Cmp->isEquality()) {
1255 // Exactly 1 possible 1? But not the high-bit because that is
1256 // canonicalized to this form.
1257 KnownBits Known = computeKnownBits(V: Cmp->getOperand(i_nocapture: 0), CxtI: &Zext);
1258 APInt KnownZeroMask(~Known.Zero);
1259 uint32_t ShAmt = KnownZeroMask.logBase2();
1260 bool IsExpectShAmt = KnownZeroMask.isPowerOf2() &&
1261 (Zext.getType()->getScalarSizeInBits() != ShAmt + 1);
1262 if (IsExpectShAmt &&
1263 (Cmp->getOperand(i_nocapture: 0)->getType() == Zext.getType() ||
1264 Cmp->getPredicate() == ICmpInst::ICMP_NE || ShAmt == 0)) {
1265 Value *In = Cmp->getOperand(i_nocapture: 0);
1266 if (ShAmt) {
1267 // Perform a logical shr by shiftamt.
1268 // Insert the shift to put the result in the low bit.
1269 In = Builder.CreateLShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: ShAmt),
1270 Name: In->getName() + ".lobit");
1271 }
1272
1273 // Toggle the low bit for "X == 0".
1274 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1275 In = Builder.CreateXor(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: 1));
1276
1277 if (Zext.getType() == In->getType())
1278 return replaceInstUsesWith(I&: Zext, V: In);
1279
1280 Value *IntCast = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false);
1281 return replaceInstUsesWith(I&: Zext, V: IntCast);
1282 }
1283 }
1284 }
1285
1286 if (Cmp->isEquality()) {
1287 // Test if a bit is clear/set using a shifted-one mask:
1288 // zext (icmp eq (and X, (1 << ShAmt)), 0) --> and (lshr (not X), ShAmt), 1
1289 // zext (icmp ne (and X, (1 << ShAmt)), 0) --> and (lshr X, ShAmt), 1
1290 Value *X, *ShAmt;
1291 if (Cmp->hasOneUse() && match(V: Cmp->getOperand(i_nocapture: 1), P: m_ZeroInt()) &&
1292 match(V: Cmp->getOperand(i_nocapture: 0),
1293 P: m_OneUse(SubPattern: m_c_And(L: m_Shl(L: m_One(), R: m_Value(V&: ShAmt)), R: m_Value(V&: X))))) {
1294 auto *And = cast<BinaryOperator>(Val: Cmp->getOperand(i_nocapture: 0));
1295 Value *Shift = And->getOperand(i_nocapture: X == And->getOperand(i_nocapture: 0) ? 1 : 0);
1296 if (Zext.getType() == And->getType() ||
1297 Cmp->getPredicate() != ICmpInst::ICMP_EQ || Shift->hasOneUse()) {
1298 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1299 X = Builder.CreateNot(V: X);
1300 Value *Lshr = Builder.CreateLShr(LHS: X, RHS: ShAmt);
1301 Value *And1 =
1302 Builder.CreateAnd(LHS: Lshr, RHS: ConstantInt::get(Ty: X->getType(), V: 1));
1303 return replaceInstUsesWith(
1304 I&: Zext, V: Builder.CreateZExtOrTrunc(V: And1, DestTy: Zext.getType()));
1305 }
1306 }
1307 }
1308
1309 return nullptr;
1310}
1311
1312/// Determine if the specified value can be computed in the specified wider type
1313/// and produce the same low bits. If not, return false.
1314///
1315/// If this function returns true, it can also return a non-zero number of bits
1316/// (in BitsToClear) which indicates that the value it computes is correct for
1317/// the zero extend, but that the additional BitsToClear bits need to be zero'd
1318/// out. For example, to promote something like:
1319///
1320/// %B = trunc i64 %A to i32
1321/// %C = lshr i32 %B, 8
1322/// %E = zext i32 %C to i64
1323///
1324/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
1325/// set to 8 to indicate that the promoted value needs to have bits 24-31
1326/// cleared in addition to bits 32-63. Since an 'and' will be generated to
1327/// clear the top bits anyway, doing this has no extra cost.
1328///
1329/// This function works on both vectors and scalars.
1330bool TypeEvaluationHelper::canEvaluateZExtd(Value *V, Type *Ty,
1331 unsigned &BitsToClear,
1332 InstCombinerImpl &IC,
1333 Instruction *CxtI) {
1334 TypeEvaluationHelper TYH;
1335 return TYH.canEvaluateZExtdImpl(V, Ty, BitsToClear, IC, CxtI);
1336}
1337bool TypeEvaluationHelper::canEvaluateZExtdImpl(Value *V, Type *Ty,
1338 unsigned &BitsToClear,
1339 InstCombinerImpl &IC,
1340 Instruction *CxtI) {
1341 BitsToClear = 0;
1342 if (canAlwaysEvaluateInType(V, Ty))
1343 return true;
1344 // We stick to the one-user limit for the ZExt transform due to the fact
1345 // that this predicate returns two values: predicate result and BitsToClear.
1346 if (canNotEvaluateInType(V, Ty))
1347 return false;
1348
1349 auto *I = cast<Instruction>(Val: V);
1350 unsigned Tmp;
1351 switch (I->getOpcode()) {
1352 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
1353 case Instruction::SExt: // zext(sext(x)) -> sext(x).
1354 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
1355 return true;
1356 case Instruction::And:
1357 case Instruction::Or:
1358 case Instruction::Xor:
1359 case Instruction::Add:
1360 case Instruction::Sub:
1361 case Instruction::Mul:
1362 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI) ||
1363 !canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CxtI))
1364 return false;
1365 // These can all be promoted if neither operand has 'bits to clear'.
1366 if (BitsToClear == 0 && Tmp == 0)
1367 return true;
1368
1369 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1370 // other side, BitsToClear is ok.
1371 if (Tmp == 0 && I->isBitwiseLogicOp()) {
1372 // We use MaskedValueIsZero here for generality, but the case we care
1373 // about the most is constant RHS.
1374 unsigned VSize = V->getType()->getScalarSizeInBits();
1375 if (IC.MaskedValueIsZero(V: I->getOperand(i: 1),
1376 Mask: APInt::getHighBitsSet(numBits: VSize, hiBitsSet: BitsToClear),
1377 CxtI)) {
1378 // If this is an And instruction and all of the BitsToClear are
1379 // known to be zero we can reset BitsToClear.
1380 if (I->getOpcode() == Instruction::And)
1381 BitsToClear = 0;
1382 return true;
1383 }
1384 }
1385
1386 // Otherwise, we don't know how to analyze this BitsToClear case yet.
1387 return false;
1388
1389 case Instruction::Shl: {
1390 // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1391 // upper bits we can reduce BitsToClear by the shift amount.
1392 uint64_t ShiftAmt;
1393 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1394 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI))
1395 return false;
1396 BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1397 return true;
1398 }
1399 return false;
1400 }
1401 case Instruction::LShr: {
1402 // We can promote lshr(x, cst) if we can promote x. This requires the
1403 // ultimate 'and' to clear out the high zero bits we're clearing out though.
1404 uint64_t ShiftAmt;
1405 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1406 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI))
1407 return false;
1408 BitsToClear += ShiftAmt;
1409 if (BitsToClear > V->getType()->getScalarSizeInBits())
1410 BitsToClear = V->getType()->getScalarSizeInBits();
1411 return true;
1412 }
1413 // Cannot promote variable LSHR.
1414 return false;
1415 }
1416 case Instruction::Select:
1417 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CxtI) ||
1418 !canEvaluateZExtdImpl(V: I->getOperand(i: 2), Ty, BitsToClear, IC, CxtI) ||
1419 // TODO: If important, we could handle the case when the BitsToClear are
1420 // known zero in the disagreeing side.
1421 Tmp != BitsToClear)
1422 return false;
1423 return true;
1424
1425 case Instruction::PHI: {
1426 // We can change a phi if we can change all operands. Note that we never
1427 // get into trouble with cyclic PHIs here because we only consider
1428 // instructions with a single use.
1429 PHINode *PN = cast<PHINode>(Val: I);
1430 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i: 0), Ty, BitsToClear, IC,
1431 CxtI))
1432 return false;
1433 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1434 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i), Ty, BitsToClear&: Tmp, IC, CxtI) ||
1435 // TODO: If important, we could handle the case when the BitsToClear
1436 // are known zero in the disagreeing input.
1437 Tmp != BitsToClear)
1438 return false;
1439 return true;
1440 }
1441 case Instruction::Call:
1442 // llvm.vscale() can always be executed in larger type, because the
1443 // value is automatically zero-extended.
1444 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I))
1445 if (II->getIntrinsicID() == Intrinsic::vscale)
1446 return true;
1447 return false;
1448 default:
1449 // TODO: Can handle more cases here.
1450 return false;
1451 }
1452}
1453
1454Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
1455 // If this zero extend is only used by a truncate, let the truncate be
1456 // eliminated before we try to optimize this zext.
1457 if (Zext.hasOneUse() && isa<TruncInst>(Val: Zext.user_back()) &&
1458 !isa<Constant>(Val: Zext.getOperand(i_nocapture: 0)))
1459 return nullptr;
1460
1461 // If one of the common conversion will work, do it.
1462 if (Instruction *Result = commonCastTransforms(CI&: Zext))
1463 return Result;
1464
1465 Value *Src = Zext.getOperand(i_nocapture: 0);
1466 Type *SrcTy = Src->getType(), *DestTy = Zext.getType();
1467
1468 // zext nneg bool x -> 0
1469 if (SrcTy->isIntOrIntVectorTy(BitWidth: 1) && Zext.hasNonNeg())
1470 return replaceInstUsesWith(I&: Zext, V: Constant::getNullValue(Ty: Zext.getType()));
1471
1472 // Try to extend the entire expression tree to the wide destination type.
1473 unsigned BitsToClear;
1474 if (shouldChangeType(From: SrcTy, To: DestTy) &&
1475 TypeEvaluationHelper::canEvaluateZExtd(V: Src, Ty: DestTy, BitsToClear, IC&: *this,
1476 CxtI: &Zext)) {
1477 assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1478 "Can't clear more bits than in SrcTy");
1479
1480 // Okay, we can transform this! Insert the new expression now.
1481 LLVM_DEBUG(
1482 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1483 " to avoid zero extend: "
1484 << Zext << '\n');
1485 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: false);
1486 assert(Res->getType() == DestTy);
1487
1488 // Preserve debug values referring to Src if the zext is its last use.
1489 if (auto *SrcOp = dyn_cast<Instruction>(Val: Src))
1490 if (SrcOp->hasOneUse())
1491 replaceAllDbgUsesWith(From&: *SrcOp, To&: *Res, DomPoint&: Zext, DT);
1492
1493 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits() - BitsToClear;
1494 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1495
1496 // If the high bits are already filled with zeros, just replace this
1497 // cast with the result.
1498 if (MaskedValueIsZero(
1499 V: Res, Mask: APInt::getHighBitsSet(numBits: DestBitSize, hiBitsSet: DestBitSize - SrcBitsKept),
1500 CxtI: &Zext))
1501 return replaceInstUsesWith(I&: Zext, V: Res);
1502
1503 // We need to emit an AND to clear the high bits.
1504 Constant *C = ConstantInt::get(Ty: Res->getType(),
1505 V: APInt::getLowBitsSet(numBits: DestBitSize, loBitsSet: SrcBitsKept));
1506 return BinaryOperator::CreateAnd(V1: Res, V2: C);
1507 }
1508
1509 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1510 // types and if the sizes are just right we can convert this into a logical
1511 // 'and' which will be much cheaper than the pair of casts.
1512 if (auto *CSrc = dyn_cast<TruncInst>(Val: Src)) { // A->B->C cast
1513 // TODO: Subsume this into EvaluateInDifferentType.
1514
1515 // Get the sizes of the types involved. We know that the intermediate type
1516 // will be smaller than A or C, but don't know the relation between A and C.
1517 Value *A = CSrc->getOperand(i_nocapture: 0);
1518 unsigned SrcSize = A->getType()->getScalarSizeInBits();
1519 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1520 unsigned DstSize = DestTy->getScalarSizeInBits();
1521 // If we're actually extending zero bits, then if
1522 // SrcSize < DstSize: zext(a & mask)
1523 // SrcSize == DstSize: a & mask
1524 // SrcSize > DstSize: trunc(a) & mask
1525 if (SrcSize < DstSize) {
1526 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1527 Constant *AndConst = ConstantInt::get(Ty: A->getType(), V: AndValue);
1528 Value *And = Builder.CreateAnd(LHS: A, RHS: AndConst, Name: CSrc->getName() + ".mask");
1529 return new ZExtInst(And, DestTy);
1530 }
1531
1532 if (SrcSize == DstSize) {
1533 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1534 return BinaryOperator::CreateAnd(V1: A, V2: ConstantInt::get(Ty: A->getType(),
1535 V: AndValue));
1536 }
1537 if (SrcSize > DstSize) {
1538 Value *Trunc = Builder.CreateTrunc(V: A, DestTy);
1539 APInt AndValue(APInt::getLowBitsSet(numBits: DstSize, loBitsSet: MidSize));
1540 return BinaryOperator::CreateAnd(V1: Trunc,
1541 V2: ConstantInt::get(Ty: Trunc->getType(),
1542 V: AndValue));
1543 }
1544 }
1545
1546 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1547 return transformZExtICmp(Cmp, Zext);
1548
1549 // zext(trunc(X) & C) -> (X & zext(C)).
1550 Constant *C;
1551 Value *X;
1552 if (match(V: Src, P: m_OneUse(SubPattern: m_And(L: m_Trunc(Op: m_Value(V&: X)), R: m_Constant(C)))) &&
1553 X->getType() == DestTy)
1554 return BinaryOperator::CreateAnd(V1: X, V2: Builder.CreateZExt(V: C, DestTy));
1555
1556 // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1557 Value *And;
1558 if (match(V: Src, P: m_OneUse(SubPattern: m_Xor(L: m_Value(V&: And), R: m_Constant(C)))) &&
1559 match(V: And, P: m_OneUse(SubPattern: m_And(L: m_Trunc(Op: m_Value(V&: X)), R: m_Specific(V: C)))) &&
1560 X->getType() == DestTy) {
1561 Value *ZC = Builder.CreateZExt(V: C, DestTy);
1562 return BinaryOperator::CreateXor(V1: Builder.CreateAnd(LHS: X, RHS: ZC), V2: ZC);
1563 }
1564
1565 // If we are truncating, masking, and then zexting back to the original type,
1566 // that's just a mask. This is not handled by canEvaluateZextd if the
1567 // intermediate values have extra uses. This could be generalized further for
1568 // a non-constant mask operand.
1569 // zext (and (trunc X), C) --> and X, (zext C)
1570 if (match(V: Src, P: m_And(L: m_Trunc(Op: m_Value(V&: X)), R: m_Constant(C))) &&
1571 X->getType() == DestTy) {
1572 Value *ZextC = Builder.CreateZExt(V: C, DestTy);
1573 return BinaryOperator::CreateAnd(V1: X, V2: ZextC);
1574 }
1575
1576 if (match(V: Src, P: m_VScale())) {
1577 if (Zext.getFunction() &&
1578 Zext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1579 Attribute Attr =
1580 Zext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1581 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
1582 unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
1583 if (Log2_32(Value: *MaxVScale) < TypeWidth)
1584 return replaceInstUsesWith(I&: Zext, V: Builder.CreateVScale(Ty: DestTy));
1585 }
1586 }
1587 }
1588
1589 if (!Zext.hasNonNeg()) {
1590 // If this zero extend is only used by a shift, add nneg flag.
1591 if (Zext.hasOneUse() &&
1592 SrcTy->getScalarSizeInBits() >
1593 Log2_64_Ceil(Value: DestTy->getScalarSizeInBits()) &&
1594 match(V: Zext.user_back(), P: m_Shift(L: m_Value(), R: m_Specific(V: &Zext)))) {
1595 Zext.setNonNeg();
1596 return &Zext;
1597 }
1598
1599 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Zext))) {
1600 Zext.setNonNeg();
1601 return &Zext;
1602 }
1603 }
1604
1605 return nullptr;
1606}
1607
1608/// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1609Instruction *InstCombinerImpl::transformSExtICmp(ICmpInst *Cmp,
1610 SExtInst &Sext) {
1611 Value *Op0 = Cmp->getOperand(i_nocapture: 0), *Op1 = Cmp->getOperand(i_nocapture: 1);
1612 ICmpInst::Predicate Pred = Cmp->getPredicate();
1613
1614 // Don't bother if Op1 isn't of vector or integer type.
1615 if (!Op1->getType()->isIntOrIntVectorTy())
1616 return nullptr;
1617
1618 if (Pred == ICmpInst::ICMP_SLT && match(V: Op1, P: m_ZeroInt())) {
1619 // sext (x <s 0) --> ashr x, 31 (all ones if negative)
1620 Value *Sh = ConstantInt::get(Ty: Op0->getType(),
1621 V: Op0->getType()->getScalarSizeInBits() - 1);
1622 Value *In = Builder.CreateAShr(LHS: Op0, RHS: Sh, Name: Op0->getName() + ".lobit");
1623 if (In->getType() != Sext.getType())
1624 In = Builder.CreateIntCast(V: In, DestTy: Sext.getType(), isSigned: true /*SExt*/);
1625
1626 return replaceInstUsesWith(I&: Sext, V: In);
1627 }
1628
1629 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Val: Op1)) {
1630 // If we know that only one bit of the LHS of the icmp can be set and we
1631 // have an equality comparison with zero or a power of 2, we can transform
1632 // the icmp and sext into bitwise/integer operations.
1633 if (Cmp->hasOneUse() &&
1634 Cmp->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1635 KnownBits Known = computeKnownBits(V: Op0, CxtI: &Sext);
1636
1637 APInt KnownZeroMask(~Known.Zero);
1638 if (KnownZeroMask.isPowerOf2()) {
1639 Value *In = Cmp->getOperand(i_nocapture: 0);
1640
1641 // If the icmp tests for a known zero bit we can constant fold it.
1642 if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1643 Value *V = Pred == ICmpInst::ICMP_NE ?
1644 ConstantInt::getAllOnesValue(Ty: Sext.getType()) :
1645 ConstantInt::getNullValue(Ty: Sext.getType());
1646 return replaceInstUsesWith(I&: Sext, V);
1647 }
1648
1649 if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1650 // sext ((x & 2^n) == 0) -> (x >> n) - 1
1651 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1652 unsigned ShiftAmt = KnownZeroMask.countr_zero();
1653 // Perform a right shift to place the desired bit in the LSB.
1654 if (ShiftAmt)
1655 In = Builder.CreateLShr(LHS: In,
1656 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1657
1658 // At this point "In" is either 1 or 0. Subtract 1 to turn
1659 // {1, 0} -> {0, -1}.
1660 In = Builder.CreateAdd(LHS: In,
1661 RHS: ConstantInt::getAllOnesValue(Ty: In->getType()),
1662 Name: "sext");
1663 } else {
1664 // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1665 // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1666 unsigned ShiftAmt = KnownZeroMask.countl_zero();
1667 // Perform a left shift to place the desired bit in the MSB.
1668 if (ShiftAmt)
1669 In = Builder.CreateShl(LHS: In,
1670 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1671
1672 // Distribute the bit over the whole bit width.
1673 In = Builder.CreateAShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(),
1674 V: KnownZeroMask.getBitWidth() - 1), Name: "sext");
1675 }
1676
1677 if (Sext.getType() == In->getType())
1678 return replaceInstUsesWith(I&: Sext, V: In);
1679 return CastInst::CreateIntegerCast(S: In, Ty: Sext.getType(), isSigned: true/*SExt*/);
1680 }
1681 }
1682 }
1683
1684 return nullptr;
1685}
1686
1687/// Return true if we can take the specified value and return it as type Ty
1688/// without inserting any new casts and without changing the value of the common
1689/// low bits. This is used by code that tries to promote integer operations to
1690/// a wider types will allow us to eliminate the extension.
1691///
1692/// This function works on both vectors and scalars.
1693///
1694bool TypeEvaluationHelper::canEvaluateSExtd(Value *V, Type *Ty) {
1695 TypeEvaluationHelper TYH;
1696 return TYH.canEvaluateSExtdImpl(V, Ty) && TYH.allPendingVisited();
1697}
1698
1699bool TypeEvaluationHelper::canEvaluateSExtdImpl(Value *V, Type *Ty) {
1700 return canEvaluate(V, Ty, Pred: [this](Value *V, Type *Ty) {
1701 return canEvaluateSExtdPred(V, Ty);
1702 });
1703}
1704
1705bool TypeEvaluationHelper::canEvaluateSExtdPred(Value *V, Type *Ty) {
1706 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
1707 "Can't sign extend type to a smaller type");
1708
1709 auto *I = cast<Instruction>(Val: V);
1710 switch (I->getOpcode()) {
1711 case Instruction::SExt: // sext(sext(x)) -> sext(x)
1712 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1713 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1714 return true;
1715 case Instruction::And:
1716 case Instruction::Or:
1717 case Instruction::Xor:
1718 case Instruction::Add:
1719 case Instruction::Sub:
1720 case Instruction::Mul:
1721 // These operators can all arbitrarily be extended if their inputs can.
1722 return canEvaluateSExtdImpl(V: I->getOperand(i: 0), Ty) &&
1723 canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty);
1724
1725 // case Instruction::Shl: TODO
1726 // case Instruction::LShr: TODO
1727
1728 case Instruction::Select:
1729 return canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty) &&
1730 canEvaluateSExtdImpl(V: I->getOperand(i: 2), Ty);
1731
1732 case Instruction::PHI: {
1733 // We can change a phi if we can change all operands. Note that we never
1734 // get into trouble with cyclic PHIs here because canEvaluate handles use
1735 // chain loops.
1736 PHINode *PN = cast<PHINode>(Val: I);
1737 for (Value *IncValue : PN->incoming_values())
1738 if (!canEvaluateSExtdImpl(V: IncValue, Ty))
1739 return false;
1740 return true;
1741 }
1742 default:
1743 // TODO: Can handle more cases here.
1744 break;
1745 }
1746
1747 return false;
1748}
1749
1750Instruction *InstCombinerImpl::visitSExt(SExtInst &Sext) {
1751 // If this sign extend is only used by a truncate, let the truncate be
1752 // eliminated before we try to optimize this sext.
1753 if (Sext.hasOneUse() && isa<TruncInst>(Val: Sext.user_back()))
1754 return nullptr;
1755
1756 if (Instruction *I = commonCastTransforms(CI&: Sext))
1757 return I;
1758
1759 Value *Src = Sext.getOperand(i_nocapture: 0);
1760 Type *SrcTy = Src->getType(), *DestTy = Sext.getType();
1761 unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1762 unsigned DestBitSize = DestTy->getScalarSizeInBits();
1763
1764 // If the value being extended is zero or positive, use a zext instead.
1765 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Sext))) {
1766 auto CI = CastInst::Create(Instruction::ZExt, S: Src, Ty: DestTy);
1767 CI->setNonNeg(true);
1768 return CI;
1769 }
1770
1771 // Try to extend the entire expression tree to the wide destination type.
1772 bool ShouldExtendExpression = true;
1773 Value *TruncSrc = nullptr;
1774 // It is not desirable to extend expression in the trunc + sext pattern when
1775 // destination type is narrower than original (pre-trunc) type.
1776 if (match(V: Src, P: m_Trunc(Op: m_Value(V&: TruncSrc))))
1777 if (TruncSrc->getType()->getScalarSizeInBits() > DestBitSize)
1778 ShouldExtendExpression = false;
1779 if (ShouldExtendExpression && shouldChangeType(From: SrcTy, To: DestTy) &&
1780 TypeEvaluationHelper::canEvaluateSExtd(V: Src, Ty: DestTy)) {
1781 // Okay, we can transform this! Insert the new expression now.
1782 LLVM_DEBUG(
1783 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1784 " to avoid sign extend: "
1785 << Sext << '\n');
1786 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: true);
1787 assert(Res->getType() == DestTy);
1788
1789 // If the high bits are already filled with sign bit, just replace this
1790 // cast with the result.
1791 if (ComputeNumSignBits(Op: Res, CxtI: &Sext) > DestBitSize - SrcBitSize)
1792 return replaceInstUsesWith(I&: Sext, V: Res);
1793
1794 // We need to emit a shl + ashr to do the sign extend.
1795 Value *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
1796 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: Res, RHS: ShAmt, Name: "sext"),
1797 V2: ShAmt);
1798 }
1799
1800 Value *X = TruncSrc;
1801 if (X) {
1802 // If the input has more sign bits than bits truncated, then convert
1803 // directly to final type.
1804 unsigned XBitSize = X->getType()->getScalarSizeInBits();
1805 bool HasNSW = cast<TruncInst>(Val: Src)->hasNoSignedWrap();
1806 if (HasNSW || (ComputeNumSignBits(Op: X, CxtI: &Sext) > XBitSize - SrcBitSize)) {
1807 auto *Res = CastInst::CreateIntegerCast(S: X, Ty: DestTy, /* isSigned */ true);
1808 if (auto *ResTrunc = dyn_cast<TruncInst>(Val: Res); ResTrunc && HasNSW)
1809 ResTrunc->setHasNoSignedWrap(true);
1810 return Res;
1811 }
1812
1813 // If input is a trunc from the destination type, then convert into shifts.
1814 if (Src->hasOneUse() && X->getType() == DestTy) {
1815 // sext (trunc X) --> ashr (shl X, C), C
1816 Constant *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
1817 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShAmt), V2: ShAmt);
1818 }
1819
1820 // If we are replacing shifted-in high zero bits with sign bits, convert
1821 // the logic shift to arithmetic shift and eliminate the cast to
1822 // intermediate type:
1823 // sext (trunc (lshr Y, C)) --> sext/trunc (ashr Y, C)
1824 Value *Y;
1825 if (Src->hasOneUse() &&
1826 match(V: X, P: m_LShr(L: m_Value(V&: Y),
1827 R: m_SpecificIntAllowPoison(V: XBitSize - SrcBitSize)))) {
1828 Value *Ashr = Builder.CreateAShr(LHS: Y, RHS: XBitSize - SrcBitSize);
1829 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
1830 }
1831 }
1832
1833 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1834 return transformSExtICmp(Cmp, Sext);
1835
1836 // If the input is a shl/ashr pair of a same constant, then this is a sign
1837 // extension from a smaller value. If we could trust arbitrary bitwidth
1838 // integers, we could turn this into a truncate to the smaller bit and then
1839 // use a sext for the whole extension. Since we don't, look deeper and check
1840 // for a truncate. If the source and dest are the same type, eliminate the
1841 // trunc and extend and just do shifts. For example, turn:
1842 // %a = trunc i32 %i to i8
1843 // %b = shl i8 %a, C
1844 // %c = ashr i8 %b, C
1845 // %d = sext i8 %c to i32
1846 // into:
1847 // %a = shl i32 %i, 32-(8-C)
1848 // %d = ashr i32 %a, 32-(8-C)
1849 Value *A = nullptr;
1850 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1851 Constant *BA = nullptr, *CA = nullptr;
1852 if (match(V: Src, P: m_AShr(L: m_Shl(L: m_Trunc(Op: m_Value(V&: A)), R: m_Constant(C&: BA)),
1853 R: m_ImmConstant(C&: CA))) &&
1854 BA->isElementWiseEqual(Y: CA) && A->getType() == DestTy) {
1855 Constant *WideCurrShAmt =
1856 ConstantFoldCastOperand(Opcode: Instruction::SExt, C: CA, DestTy, DL);
1857 assert(WideCurrShAmt && "Constant folding of ImmConstant cannot fail");
1858 Constant *NumLowbitsLeft = ConstantExpr::getSub(
1859 C1: ConstantInt::get(Ty: DestTy, V: SrcTy->getScalarSizeInBits()), C2: WideCurrShAmt);
1860 Constant *NewShAmt = ConstantExpr::getSub(
1861 C1: ConstantInt::get(Ty: DestTy, V: DestTy->getScalarSizeInBits()),
1862 C2: NumLowbitsLeft);
1863 NewShAmt =
1864 Constant::mergeUndefsWith(C: Constant::mergeUndefsWith(C: NewShAmt, Other: BA), Other: CA);
1865 A = Builder.CreateShl(LHS: A, RHS: NewShAmt, Name: Sext.getName());
1866 return BinaryOperator::CreateAShr(V1: A, V2: NewShAmt);
1867 }
1868
1869 // Splatting a bit of constant-index across a value:
1870 // sext (ashr (trunc iN X to iM), M-1) to iN --> ashr (shl X, N-M), N-1
1871 // If the dest type is different, use a cast (adjust use check).
1872 if (match(V: Src, P: m_OneUse(SubPattern: m_AShr(L: m_Trunc(Op: m_Value(V&: X)),
1873 R: m_SpecificInt(V: SrcBitSize - 1))))) {
1874 Type *XTy = X->getType();
1875 unsigned XBitSize = XTy->getScalarSizeInBits();
1876 Constant *ShlAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - SrcBitSize);
1877 Constant *AshrAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - 1);
1878 if (XTy == DestTy)
1879 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShlAmtC),
1880 V2: AshrAmtC);
1881 if (cast<BinaryOperator>(Val: Src)->getOperand(i_nocapture: 0)->hasOneUse()) {
1882 Value *Ashr = Builder.CreateAShr(LHS: Builder.CreateShl(LHS: X, RHS: ShlAmtC), RHS: AshrAmtC);
1883 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
1884 }
1885 }
1886
1887 if (match(V: Src, P: m_VScale())) {
1888 if (Sext.getFunction() &&
1889 Sext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1890 Attribute Attr =
1891 Sext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1892 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
1893 if (Log2_32(Value: *MaxVScale) < (SrcBitSize - 1))
1894 return replaceInstUsesWith(I&: Sext, V: Builder.CreateVScale(Ty: DestTy));
1895 }
1896 }
1897
1898 return nullptr;
1899}
1900
1901/// Return a Constant* for the specified floating-point constant if it fits
1902/// in the specified FP type without changing its value.
1903static bool fitsInFPType(APFloat F, const fltSemantics &Sem) {
1904 bool losesInfo;
1905 (void)F.convert(ToSemantics: Sem, RM: APFloat::rmNearestTiesToEven, losesInfo: &losesInfo);
1906 return !losesInfo;
1907}
1908
1909static Type *shrinkFPConstant(LLVMContext &Ctx, const APFloat &F,
1910 bool PreferBFloat) {
1911 // See if the value can be truncated to bfloat and then reextended.
1912 if (PreferBFloat && fitsInFPType(F, Sem: APFloat::BFloat()))
1913 return Type::getBFloatTy(C&: Ctx);
1914 // See if the value can be truncated to half and then reextended.
1915 if (!PreferBFloat && fitsInFPType(F, Sem: APFloat::IEEEhalf()))
1916 return Type::getHalfTy(C&: Ctx);
1917 // See if the value can be truncated to float and then reextended.
1918 if (fitsInFPType(F, Sem: APFloat::IEEEsingle()))
1919 return Type::getFloatTy(C&: Ctx);
1920 if (&F.getSemantics() == &APFloat::IEEEdouble())
1921 return nullptr; // Won't shrink.
1922 // See if the value can be truncated to double and then reextended.
1923 if (fitsInFPType(F, Sem: APFloat::IEEEdouble()))
1924 return Type::getDoubleTy(C&: Ctx);
1925 // Don't try to shrink to various long double types.
1926 return nullptr;
1927}
1928
1929static Type *shrinkFPConstant(ConstantFP *CFP, bool PreferBFloat) {
1930 Type *Ty = CFP->getType();
1931 if (Ty->getScalarType()->isPPC_FP128Ty())
1932 return nullptr; // No constant folding of this.
1933
1934 Type *ShrinkTy =
1935 shrinkFPConstant(Ctx&: CFP->getContext(), F: CFP->getValueAPF(), PreferBFloat);
1936 if (ShrinkTy)
1937 if (auto *VecTy = dyn_cast<VectorType>(Val: Ty))
1938 ShrinkTy = VectorType::get(ElementType: ShrinkTy, Other: VecTy);
1939
1940 return ShrinkTy;
1941}
1942
1943// Determine if this is a vector of ConstantFPs and if so, return the minimal
1944// type we can safely truncate all elements to.
1945static Type *shrinkFPConstantVector(Value *V, bool PreferBFloat) {
1946 auto *CV = dyn_cast<Constant>(Val: V);
1947 auto *CVVTy = dyn_cast<FixedVectorType>(Val: V->getType());
1948 if (!CV || !CVVTy)
1949 return nullptr;
1950
1951 Type *MinType = nullptr;
1952
1953 unsigned NumElts = CVVTy->getNumElements();
1954
1955 // For fixed-width vectors we find the minimal type by looking
1956 // through the constant values of the vector.
1957 for (unsigned i = 0; i != NumElts; ++i) {
1958 if (isa<UndefValue>(Val: CV->getAggregateElement(Elt: i)))
1959 continue;
1960
1961 auto *CFP = dyn_cast_or_null<ConstantFP>(Val: CV->getAggregateElement(Elt: i));
1962 if (!CFP)
1963 return nullptr;
1964
1965 Type *T = shrinkFPConstant(CFP, PreferBFloat);
1966 if (!T)
1967 return nullptr;
1968
1969 // If we haven't found a type yet or this type has a larger mantissa than
1970 // our previous type, this is our new minimal type.
1971 if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
1972 MinType = T;
1973 }
1974
1975 // Make a vector type from the minimal type.
1976 return MinType ? FixedVectorType::get(ElementType: MinType, NumElts) : nullptr;
1977}
1978
1979/// Find the minimum FP type we can safely truncate to.
1980static Type *getMinimumFPType(Value *V, bool PreferBFloat) {
1981 if (auto *FPExt = dyn_cast<FPExtInst>(Val: V))
1982 return FPExt->getOperand(i_nocapture: 0)->getType();
1983
1984 // If this value is a constant, return the constant in the smallest FP type
1985 // that can accurately represent it. This allows us to turn
1986 // (float)((double)X+2.0) into x+2.0f.
1987 if (auto *CFP = dyn_cast<ConstantFP>(Val: V))
1988 if (Type *T = shrinkFPConstant(CFP, PreferBFloat))
1989 return T;
1990
1991 // Try to shrink scalable and fixed splat vectors.
1992 if (auto *FPC = dyn_cast<Constant>(Val: V))
1993 if (auto *VTy = dyn_cast<VectorType>(Val: V->getType()))
1994 if (auto *Splat = dyn_cast_or_null<ConstantFP>(Val: FPC->getSplatValue()))
1995 if (Type *T = shrinkFPConstant(CFP: Splat, PreferBFloat))
1996 return VectorType::get(ElementType: T, Other: VTy);
1997
1998 // Try to shrink a vector of FP constants. This returns nullptr on scalable
1999 // vectors
2000 if (Type *T = shrinkFPConstantVector(V, PreferBFloat))
2001 return T;
2002
2003 return V->getType();
2004}
2005
2006/// Return true if the cast from integer to FP can be proven to be exact for all
2007/// possible inputs (the conversion does not lose any precision).
2008static bool isKnownExactCastIntToFP(CastInst &I, InstCombinerImpl &IC) {
2009 CastInst::CastOps Opcode = I.getOpcode();
2010 assert((Opcode == CastInst::SIToFP || Opcode == CastInst::UIToFP) &&
2011 "Unexpected cast");
2012 Value *Src = I.getOperand(i_nocapture: 0);
2013 Type *SrcTy = Src->getType();
2014 Type *FPTy = I.getType();
2015 bool IsSigned = Opcode == Instruction::SIToFP;
2016 int SrcSize = (int)SrcTy->getScalarSizeInBits() - IsSigned;
2017
2018 // Easy case - if the source integer type has less bits than the FP mantissa,
2019 // then the cast must be exact.
2020 int DestNumSigBits = FPTy->getFPMantissaWidth();
2021 if (SrcSize <= DestNumSigBits)
2022 return true;
2023
2024 // Cast from FP to integer and back to FP is independent of the intermediate
2025 // integer width because of poison on overflow.
2026 Value *F;
2027 if (match(V: Src, P: m_FPToSI(Op: m_Value(V&: F))) || match(V: Src, P: m_FPToUI(Op: m_Value(V&: F)))) {
2028 // If this is uitofp (fptosi F), the source needs an extra bit to avoid
2029 // potential rounding of negative FP input values.
2030 int SrcNumSigBits = F->getType()->getFPMantissaWidth();
2031 if (!IsSigned && match(V: Src, P: m_FPToSI(Op: m_Value())))
2032 SrcNumSigBits++;
2033
2034 // [su]itofp (fpto[su]i F) --> exact if the source type has less or equal
2035 // significant bits than the destination (and make sure neither type is
2036 // weird -- ppc_fp128).
2037 if (SrcNumSigBits > 0 && DestNumSigBits > 0 &&
2038 SrcNumSigBits <= DestNumSigBits)
2039 return true;
2040 }
2041
2042 // TODO:
2043 // Try harder to find if the source integer type has less significant bits.
2044 // For example, compute number of sign bits.
2045 KnownBits SrcKnown = IC.computeKnownBits(V: Src, CxtI: &I);
2046 int SigBits = (int)SrcTy->getScalarSizeInBits() -
2047 SrcKnown.countMinLeadingZeros() -
2048 SrcKnown.countMinTrailingZeros();
2049 if (SigBits <= DestNumSigBits)
2050 return true;
2051
2052 return false;
2053}
2054
2055Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {
2056 if (Instruction *I = commonCastTransforms(CI&: FPT))
2057 return I;
2058
2059 // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
2060 // simplify this expression to avoid one or more of the trunc/extend
2061 // operations if we can do so without changing the numerical results.
2062 //
2063 // The exact manner in which the widths of the operands interact to limit
2064 // what we can and cannot do safely varies from operation to operation, and
2065 // is explained below in the various case statements.
2066 Type *Ty = FPT.getType();
2067 auto *BO = dyn_cast<BinaryOperator>(Val: FPT.getOperand(i_nocapture: 0));
2068 if (BO && BO->hasOneUse()) {
2069 bool PreferBFloat = Ty->getScalarType()->isBFloatTy();
2070 Type *LHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 0), PreferBFloat);
2071 Type *RHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 1), PreferBFloat);
2072 unsigned OpWidth = BO->getType()->getFPMantissaWidth();
2073 unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
2074 unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
2075 unsigned SrcWidth = std::max(a: LHSWidth, b: RHSWidth);
2076 unsigned DstWidth = Ty->getFPMantissaWidth();
2077 switch (BO->getOpcode()) {
2078 default: break;
2079 case Instruction::FAdd:
2080 case Instruction::FSub:
2081 // For addition and subtraction, the infinitely precise result can
2082 // essentially be arbitrarily wide; proving that double rounding
2083 // will not occur because the result of OpI is exact (as we will for
2084 // FMul, for example) is hopeless. However, we *can* nonetheless
2085 // frequently know that double rounding cannot occur (or that it is
2086 // innocuous) by taking advantage of the specific structure of
2087 // infinitely-precise results that admit double rounding.
2088 //
2089 // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
2090 // to represent both sources, we can guarantee that the double
2091 // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
2092 // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
2093 // for proof of this fact).
2094 //
2095 // Note: Figueroa does not consider the case where DstFormat !=
2096 // SrcFormat. It's possible (likely even!) that this analysis
2097 // could be tightened for those cases, but they are rare (the main
2098 // case of interest here is (float)((double)float + float)).
2099 if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
2100 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2101 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2102 Instruction *RI = BinaryOperator::Create(Op: BO->getOpcode(), S1: LHS, S2: RHS);
2103 RI->copyFastMathFlags(I: BO);
2104 return RI;
2105 }
2106 break;
2107 case Instruction::FMul:
2108 // For multiplication, the infinitely precise result has at most
2109 // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
2110 // that such a value can be exactly represented, then no double
2111 // rounding can possibly occur; we can safely perform the operation
2112 // in the destination format if it can represent both sources.
2113 if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
2114 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2115 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2116 return BinaryOperator::CreateFMulFMF(V1: LHS, V2: RHS, FMFSource: BO);
2117 }
2118 break;
2119 case Instruction::FDiv:
2120 // For division, we use again use the bound from Figueroa's
2121 // dissertation. I am entirely certain that this bound can be
2122 // tightened in the unbalanced operand case by an analysis based on
2123 // the diophantine rational approximation bound, but the well-known
2124 // condition used here is a good conservative first pass.
2125 // TODO: Tighten bound via rigorous analysis of the unbalanced case.
2126 if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
2127 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2128 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2129 return BinaryOperator::CreateFDivFMF(V1: LHS, V2: RHS, FMFSource: BO);
2130 }
2131 break;
2132 case Instruction::FRem: {
2133 // Remainder is straightforward. Remainder is always exact, so the
2134 // type of OpI doesn't enter into things at all. We simply evaluate
2135 // in whichever source type is larger, then convert to the
2136 // destination type.
2137 if (SrcWidth == OpWidth)
2138 break;
2139 Value *LHS, *RHS;
2140 if (LHSWidth == SrcWidth) {
2141 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: LHSMinType);
2142 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: LHSMinType);
2143 } else {
2144 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: RHSMinType);
2145 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: RHSMinType);
2146 }
2147
2148 Value *ExactResult = Builder.CreateFRemFMF(L: LHS, R: RHS, FMFSource: BO);
2149 return CastInst::CreateFPCast(S: ExactResult, Ty);
2150 }
2151 }
2152 }
2153
2154 // (fptrunc (fneg x)) -> (fneg (fptrunc x))
2155 Value *X;
2156 Instruction *Op = dyn_cast<Instruction>(Val: FPT.getOperand(i_nocapture: 0));
2157 if (Op && Op->hasOneUse()) {
2158 FastMathFlags FMF = FPT.getFastMathFlags();
2159 if (auto *FPMO = dyn_cast<FPMathOperator>(Val: Op))
2160 FMF &= FPMO->getFastMathFlags();
2161
2162 if (match(V: Op, P: m_FNeg(X: m_Value(V&: X)))) {
2163 Value *InnerTrunc = Builder.CreateFPTruncFMF(V: X, DestTy: Ty, FMFSource: FMF);
2164 Value *Neg = Builder.CreateFNegFMF(V: InnerTrunc, FMFSource: FMF);
2165 return replaceInstUsesWith(I&: FPT, V: Neg);
2166 }
2167
2168 // If we are truncating a select that has an extended operand, we can
2169 // narrow the other operand and do the select as a narrow op.
2170 Value *Cond, *X, *Y;
2171 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_FPExt(Op: m_Value(V&: X)), R: m_Value(V&: Y))) &&
2172 X->getType() == Ty) {
2173 // fptrunc (select Cond, (fpext X), Y --> select Cond, X, (fptrunc Y)
2174 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2175 Value *Sel =
2176 Builder.CreateSelectFMF(C: Cond, True: X, False: NarrowY, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2177 return replaceInstUsesWith(I&: FPT, V: Sel);
2178 }
2179 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: Y), R: m_FPExt(Op: m_Value(V&: X)))) &&
2180 X->getType() == Ty) {
2181 // fptrunc (select Cond, Y, (fpext X) --> select Cond, (fptrunc Y), X
2182 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2183 Value *Sel =
2184 Builder.CreateSelectFMF(C: Cond, True: NarrowY, False: X, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2185 return replaceInstUsesWith(I&: FPT, V: Sel);
2186 }
2187 }
2188
2189 if (auto *II = dyn_cast<IntrinsicInst>(Val: FPT.getOperand(i_nocapture: 0))) {
2190 switch (II->getIntrinsicID()) {
2191 default: break;
2192 case Intrinsic::ceil:
2193 case Intrinsic::fabs:
2194 case Intrinsic::floor:
2195 case Intrinsic::nearbyint:
2196 case Intrinsic::rint:
2197 case Intrinsic::round:
2198 case Intrinsic::roundeven:
2199 case Intrinsic::trunc: {
2200 Value *Src = II->getArgOperand(i: 0);
2201 if (!Src->hasOneUse())
2202 break;
2203
2204 // Except for fabs, this transformation requires the input of the unary FP
2205 // operation to be itself an fpext from the type to which we're
2206 // truncating.
2207 if (II->getIntrinsicID() != Intrinsic::fabs) {
2208 FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Val: Src);
2209 if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
2210 break;
2211 }
2212
2213 // Do unary FP operation on smaller type.
2214 // (fptrunc (fabs x)) -> (fabs (fptrunc x))
2215 Value *InnerTrunc = Builder.CreateFPTrunc(V: Src, DestTy: Ty);
2216 Function *Overload = Intrinsic::getOrInsertDeclaration(
2217 M: FPT.getModule(), id: II->getIntrinsicID(), Tys: Ty);
2218 SmallVector<OperandBundleDef, 1> OpBundles;
2219 II->getOperandBundlesAsDefs(Defs&: OpBundles);
2220 CallInst *NewCI =
2221 CallInst::Create(Func: Overload, Args: {InnerTrunc}, Bundles: OpBundles, NameStr: II->getName());
2222 // A normal value may be converted to an infinity. It means that we cannot
2223 // propagate ninf from the intrinsic. So we propagate FMF from fptrunc.
2224 NewCI->copyFastMathFlags(I: &FPT);
2225 return NewCI;
2226 }
2227 }
2228 }
2229
2230 if (Instruction *I = shrinkInsertElt(Trunc&: FPT, Builder))
2231 return I;
2232
2233 Value *Src = FPT.getOperand(i_nocapture: 0);
2234 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2235 auto *FPCast = cast<CastInst>(Val: Src);
2236 if (isKnownExactCastIntToFP(I&: *FPCast, IC&: *this))
2237 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2238 }
2239
2240 return nullptr;
2241}
2242
2243Instruction *InstCombinerImpl::visitFPExt(CastInst &FPExt) {
2244 // If the source operand is a cast from integer to FP and known exact, then
2245 // cast the integer operand directly to the destination type.
2246 Type *Ty = FPExt.getType();
2247 Value *Src = FPExt.getOperand(i_nocapture: 0);
2248 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2249 auto *FPCast = cast<CastInst>(Val: Src);
2250 if (isKnownExactCastIntToFP(I&: *FPCast, IC&: *this))
2251 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2252 }
2253
2254 return commonCastTransforms(CI&: FPExt);
2255}
2256
2257/// fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
2258/// This is safe if the intermediate type has enough bits in its mantissa to
2259/// accurately represent all values of X. For example, this won't work with
2260/// i64 -> float -> i64.
2261Instruction *InstCombinerImpl::foldItoFPtoI(CastInst &FI) {
2262 if (!isa<UIToFPInst>(Val: FI.getOperand(i_nocapture: 0)) && !isa<SIToFPInst>(Val: FI.getOperand(i_nocapture: 0)))
2263 return nullptr;
2264
2265 auto *OpI = cast<CastInst>(Val: FI.getOperand(i_nocapture: 0));
2266 Value *X = OpI->getOperand(i_nocapture: 0);
2267 Type *XType = X->getType();
2268 Type *DestType = FI.getType();
2269 bool IsOutputSigned = isa<FPToSIInst>(Val: FI);
2270
2271 // Since we can assume the conversion won't overflow, our decision as to
2272 // whether the input will fit in the float should depend on the minimum
2273 // of the input range and output range.
2274
2275 // This means this is also safe for a signed input and unsigned output, since
2276 // a negative input would lead to undefined behavior.
2277 if (!isKnownExactCastIntToFP(I&: *OpI, IC&: *this)) {
2278 // The first cast may not round exactly based on the source integer width
2279 // and FP width, but the overflow UB rules can still allow this to fold.
2280 // If the destination type is narrow, that means the intermediate FP value
2281 // must be large enough to hold the source value exactly.
2282 // For example, (uint8_t)((float)(uint32_t 16777217) is undefined behavior.
2283 int OutputSize = (int)DestType->getScalarSizeInBits();
2284 if (OutputSize > OpI->getType()->getFPMantissaWidth())
2285 return nullptr;
2286 }
2287
2288 if (DestType->getScalarSizeInBits() > XType->getScalarSizeInBits()) {
2289 bool IsInputSigned = isa<SIToFPInst>(Val: OpI);
2290 if (IsInputSigned && IsOutputSigned)
2291 return new SExtInst(X, DestType);
2292 return new ZExtInst(X, DestType);
2293 }
2294 if (DestType->getScalarSizeInBits() < XType->getScalarSizeInBits())
2295 return new TruncInst(X, DestType);
2296
2297 assert(XType == DestType && "Unexpected types for int to FP to int casts");
2298 return replaceInstUsesWith(I&: FI, V: X);
2299}
2300
2301static Instruction *foldFPtoI(Instruction &FI, InstCombiner &IC) {
2302 // fpto{u/s}i non-norm --> 0
2303 FPClassTest Mask =
2304 FI.getOpcode() == Instruction::FPToUI ? fcPosNormal : fcNormal;
2305 KnownFPClass FPClass = computeKnownFPClass(
2306 V: FI.getOperand(i: 0), InterestedClasses: Mask, SQ: IC.getSimplifyQuery().getWithInstruction(I: &FI));
2307 if (FPClass.isKnownNever(Mask))
2308 return IC.replaceInstUsesWith(I&: FI, V: ConstantInt::getNullValue(Ty: FI.getType()));
2309
2310 return nullptr;
2311}
2312
2313Instruction *InstCombinerImpl::visitFPToUI(FPToUIInst &FI) {
2314 if (Instruction *I = foldItoFPtoI(FI))
2315 return I;
2316
2317 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2318 return I;
2319
2320 return commonCastTransforms(CI&: FI);
2321}
2322
2323Instruction *InstCombinerImpl::visitFPToSI(FPToSIInst &FI) {
2324 if (Instruction *I = foldItoFPtoI(FI))
2325 return I;
2326
2327 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2328 return I;
2329
2330 return commonCastTransforms(CI&: FI);
2331}
2332
2333Instruction *InstCombinerImpl::visitUIToFP(CastInst &CI) {
2334 if (Instruction *R = commonCastTransforms(CI))
2335 return R;
2336 if (!CI.hasNonNeg() && isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2337 CI.setNonNeg();
2338 return &CI;
2339 }
2340 return nullptr;
2341}
2342
2343Instruction *InstCombinerImpl::visitSIToFP(CastInst &CI) {
2344 if (Instruction *R = commonCastTransforms(CI))
2345 return R;
2346 if (isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2347 auto *UI =
2348 CastInst::Create(Instruction::UIToFP, S: CI.getOperand(i_nocapture: 0), Ty: CI.getType());
2349 UI->setNonNeg(true);
2350 return UI;
2351 }
2352 return nullptr;
2353}
2354
2355Instruction *InstCombinerImpl::visitIntToPtr(IntToPtrInst &CI) {
2356 // If the source integer type is not the intptr_t type for this target, do a
2357 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
2358 // cast to be exposed to other transforms.
2359 unsigned AS = CI.getAddressSpace();
2360 if (CI.getOperand(i_nocapture: 0)->getType()->getScalarSizeInBits() !=
2361 DL.getPointerSizeInBits(AS)) {
2362 Type *Ty = CI.getOperand(i_nocapture: 0)->getType()->getWithNewType(
2363 EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2364 Value *P = Builder.CreateZExtOrTrunc(V: CI.getOperand(i_nocapture: 0), DestTy: Ty);
2365 return new IntToPtrInst(P, CI.getType());
2366 }
2367
2368 // Replace (inttoptr (add (ptrtoint %Base), %Offset)) with
2369 // (getelementptr i8, %Base, %Offset) if the pointer is only used as integer
2370 // value.
2371 Value *Base;
2372 Value *Offset;
2373 auto UsesPointerAsInt = [](User *U) {
2374 if (isa<ICmpInst, PtrToIntInst>(Val: U))
2375 return true;
2376 if (auto *P = dyn_cast<PHINode>(Val: U))
2377 return P->hasOneUse() && isa<ICmpInst, PtrToIntInst>(Val: *P->user_begin());
2378 return false;
2379 };
2380 if (match(V: CI.getOperand(i_nocapture: 0),
2381 P: m_OneUse(SubPattern: m_c_Add(L: m_PtrToIntSameSize(DL, Op: m_Value(V&: Base)),
2382 R: m_Value(V&: Offset)))) &&
2383 CI.getType()->getPointerAddressSpace() ==
2384 Base->getType()->getPointerAddressSpace() &&
2385 all_of(Range: CI.users(), P: UsesPointerAsInt)) {
2386 return GetElementPtrInst::Create(PointeeType: Builder.getInt8Ty(), Ptr: Base, IdxList: Offset);
2387 }
2388
2389 if (Instruction *I = commonCastTransforms(CI))
2390 return I;
2391
2392 return nullptr;
2393}
2394
2395Value *InstCombinerImpl::foldPtrToIntOrAddrOfGEP(Type *IntTy, Value *Ptr) {
2396 // Look through chain of one-use GEPs.
2397 Type *PtrTy = Ptr->getType();
2398 SmallVector<GEPOperator *> GEPs;
2399 while (true) {
2400 auto *GEP = dyn_cast<GEPOperator>(Val: Ptr);
2401 if (!GEP || !GEP->hasOneUse())
2402 break;
2403 GEPs.push_back(Elt: GEP);
2404 Ptr = GEP->getPointerOperand();
2405 }
2406
2407 // Don't handle case where GEP converts from pointer to vector.
2408 if (GEPs.empty() || PtrTy != Ptr->getType())
2409 return nullptr;
2410
2411 // Check whether we know the integer value of the base pointer.
2412 Value *Res;
2413 Type *IdxTy = DL.getIndexType(PtrTy);
2414 if (match(V: Ptr, P: m_OneUse(SubPattern: m_IntToPtr(Op: m_Value(V&: Res)))) &&
2415 Res->getType() == IntTy && IntTy == IdxTy) {
2416 // pass
2417 } else if (isa<ConstantPointerNull>(Val: Ptr)) {
2418 Res = Constant::getNullValue(Ty: IdxTy);
2419 } else {
2420 return nullptr;
2421 }
2422
2423 // Perform the entire operation on integers instead.
2424 for (GEPOperator *GEP : reverse(C&: GEPs)) {
2425 Value *Offset = EmitGEPOffset(GEP);
2426 Res = Builder.CreateAdd(LHS: Res, RHS: Offset, Name: "", HasNUW: GEP->hasNoUnsignedWrap());
2427 }
2428 return Builder.CreateZExtOrTrunc(V: Res, DestTy: IntTy);
2429}
2430
2431Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
2432 // If the destination integer type is not the intptr_t type for this target,
2433 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
2434 // to be exposed to other transforms.
2435 Value *SrcOp = CI.getPointerOperand();
2436 Type *SrcTy = SrcOp->getType();
2437 Type *Ty = CI.getType();
2438 unsigned AS = CI.getPointerAddressSpace();
2439 unsigned TySize = Ty->getScalarSizeInBits();
2440 unsigned PtrSize = DL.getPointerSizeInBits(AS);
2441 if (TySize != PtrSize) {
2442 Type *IntPtrTy =
2443 SrcTy->getWithNewType(EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2444 Value *P = Builder.CreatePtrToInt(V: SrcOp, DestTy: IntPtrTy);
2445 return CastInst::CreateIntegerCast(S: P, Ty, /*isSigned=*/false);
2446 }
2447
2448 // (ptrtoint (ptrmask P, M))
2449 // -> (and (ptrtoint P), M)
2450 // This is generally beneficial as `and` is better supported than `ptrmask`.
2451 Value *Ptr, *Mask;
2452 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(Op0: m_Value(V&: Ptr),
2453 Op1: m_Value(V&: Mask)))) &&
2454 Mask->getType() == Ty)
2455 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToInt(V: Ptr, DestTy: Ty), V2: Mask);
2456
2457 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2458 return replaceInstUsesWith(I&: CI, V);
2459
2460 Value *Vec, *Scalar, *Index;
2461 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_InsertElt(Val: m_IntToPtr(Op: m_Value(V&: Vec)),
2462 Elt: m_Value(V&: Scalar), Idx: m_Value(V&: Index)))) &&
2463 Vec->getType() == Ty) {
2464 assert(Vec->getType()->getScalarSizeInBits() == PtrSize && "Wrong type");
2465 // Convert the scalar to int followed by insert to eliminate one cast:
2466 // p2i (ins (i2p Vec), Scalar, Index --> ins Vec, (p2i Scalar), Index
2467 Value *NewCast = Builder.CreatePtrToInt(V: Scalar, DestTy: Ty->getScalarType());
2468 return InsertElementInst::Create(Vec, NewElt: NewCast, Idx: Index);
2469 }
2470
2471 return commonCastTransforms(CI);
2472}
2473
2474Instruction *InstCombinerImpl::visitPtrToAddr(PtrToAddrInst &CI) {
2475 Value *SrcOp = CI.getPointerOperand();
2476 Type *Ty = CI.getType();
2477
2478 // (ptrtoaddr (ptrmask P, M))
2479 // -> (and (ptrtoaddr P), M)
2480 // This is generally beneficial as `and` is better supported than `ptrmask`.
2481 Value *Ptr, *Mask;
2482 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(Op0: m_Value(V&: Ptr),
2483 Op1: m_Value(V&: Mask)))) &&
2484 Mask->getType() == Ty)
2485 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToAddr(V: Ptr), V2: Mask);
2486
2487 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2488 return replaceInstUsesWith(I&: CI, V);
2489
2490 // FIXME: Implement variants of ptrtoint folds.
2491 return commonCastTransforms(CI);
2492}
2493
2494/// This input value (which is known to have vector type) is being zero extended
2495/// or truncated to the specified vector type. Since the zext/trunc is done
2496/// using an integer type, we have a (bitcast(cast(bitcast))) pattern,
2497/// endianness will impact which end of the vector that is extended or
2498/// truncated.
2499///
2500/// A vector is always stored with index 0 at the lowest address, which
2501/// corresponds to the most significant bits for a big endian stored integer and
2502/// the least significant bits for little endian. A trunc/zext of an integer
2503/// impacts the big end of the integer. Thus, we need to add/remove elements at
2504/// the front of the vector for big endian targets, and the back of the vector
2505/// for little endian targets.
2506///
2507/// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
2508///
2509/// The source and destination vector types may have different element types.
2510static Instruction *
2511optimizeVectorResizeWithIntegerBitCasts(Value *InVal, VectorType *DestTy,
2512 InstCombinerImpl &IC) {
2513 // We can only do this optimization if the output is a multiple of the input
2514 // element size, or the input is a multiple of the output element size.
2515 // Convert the input type to have the same element type as the output.
2516 VectorType *SrcTy = cast<VectorType>(Val: InVal->getType());
2517
2518 if (SrcTy->getElementType() != DestTy->getElementType()) {
2519 // The input types don't need to be identical, but for now they must be the
2520 // same size. There is no specific reason we couldn't handle things like
2521 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
2522 // there yet.
2523 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
2524 DestTy->getElementType()->getPrimitiveSizeInBits())
2525 return nullptr;
2526
2527 SrcTy =
2528 FixedVectorType::get(ElementType: DestTy->getElementType(),
2529 NumElts: cast<FixedVectorType>(Val: SrcTy)->getNumElements());
2530 InVal = IC.Builder.CreateBitCast(V: InVal, DestTy: SrcTy);
2531 }
2532
2533 bool IsBigEndian = IC.getDataLayout().isBigEndian();
2534 unsigned SrcElts = cast<FixedVectorType>(Val: SrcTy)->getNumElements();
2535 unsigned DestElts = cast<FixedVectorType>(Val: DestTy)->getNumElements();
2536
2537 assert(SrcElts != DestElts && "Element counts should be different.");
2538
2539 // Now that the element types match, get the shuffle mask and RHS of the
2540 // shuffle to use, which depends on whether we're increasing or decreasing the
2541 // size of the input.
2542 auto ShuffleMaskStorage = llvm::to_vector<16>(Range: llvm::seq<int>(Begin: 0, End: SrcElts));
2543 ArrayRef<int> ShuffleMask;
2544 Value *V2;
2545
2546 if (SrcElts > DestElts) {
2547 // If we're shrinking the number of elements (rewriting an integer
2548 // truncate), just shuffle in the elements corresponding to the least
2549 // significant bits from the input and use poison as the second shuffle
2550 // input.
2551 V2 = PoisonValue::get(T: SrcTy);
2552 // Make sure the shuffle mask selects the "least significant bits" by
2553 // keeping elements from back of the src vector for big endian, and from the
2554 // front for little endian.
2555 ShuffleMask = ShuffleMaskStorage;
2556 if (IsBigEndian)
2557 ShuffleMask = ShuffleMask.take_back(N: DestElts);
2558 else
2559 ShuffleMask = ShuffleMask.take_front(N: DestElts);
2560 } else {
2561 // If we're increasing the number of elements (rewriting an integer zext),
2562 // shuffle in all of the elements from InVal. Fill the rest of the result
2563 // elements with zeros from a constant zero.
2564 V2 = Constant::getNullValue(Ty: SrcTy);
2565 // Use first elt from V2 when indicating zero in the shuffle mask.
2566 uint32_t NullElt = SrcElts;
2567 // Extend with null values in the "most significant bits" by adding elements
2568 // in front of the src vector for big endian, and at the back for little
2569 // endian.
2570 unsigned DeltaElts = DestElts - SrcElts;
2571 if (IsBigEndian)
2572 ShuffleMaskStorage.insert(I: ShuffleMaskStorage.begin(), NumToInsert: DeltaElts, Elt: NullElt);
2573 else
2574 ShuffleMaskStorage.append(NumInputs: DeltaElts, Elt: NullElt);
2575 ShuffleMask = ShuffleMaskStorage;
2576 }
2577
2578 return new ShuffleVectorInst(InVal, V2, ShuffleMask);
2579}
2580
2581static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
2582 return Value % Ty->getPrimitiveSizeInBits() == 0;
2583}
2584
2585static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
2586 return Value / Ty->getPrimitiveSizeInBits();
2587}
2588
2589/// V is a value which is inserted into a vector of VecEltTy.
2590/// Look through the value to see if we can decompose it into
2591/// insertions into the vector. See the example in the comment for
2592/// OptimizeIntegerToVectorInsertions for the pattern this handles.
2593/// The type of V is always a non-zero multiple of VecEltTy's size.
2594/// Shift is the number of bits between the lsb of V and the lsb of
2595/// the vector.
2596///
2597/// This returns false if the pattern can't be matched or true if it can,
2598/// filling in Elements with the elements found here.
2599static bool collectInsertionElements(Value *V, unsigned Shift,
2600 SmallVectorImpl<Value *> &Elements,
2601 Type *VecEltTy, bool isBigEndian) {
2602 assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
2603 "Shift should be a multiple of the element type size");
2604
2605 // Undef values never contribute useful bits to the result.
2606 if (isa<UndefValue>(Val: V)) return true;
2607
2608 // If we got down to a value of the right type, we win, try inserting into the
2609 // right element.
2610 if (V->getType() == VecEltTy) {
2611 // Inserting null doesn't actually insert any elements.
2612 if (Constant *C = dyn_cast<Constant>(Val: V))
2613 if (C->isNullValue())
2614 return true;
2615
2616 unsigned ElementIndex = getTypeSizeIndex(Value: Shift, Ty: VecEltTy);
2617 if (isBigEndian)
2618 ElementIndex = Elements.size() - ElementIndex - 1;
2619
2620 // Fail if multiple elements are inserted into this slot.
2621 if (Elements[ElementIndex])
2622 return false;
2623
2624 Elements[ElementIndex] = V;
2625 return true;
2626 }
2627
2628 if (Constant *C = dyn_cast<Constant>(Val: V)) {
2629 // Figure out the # elements this provides, and bitcast it or slice it up
2630 // as required.
2631 unsigned NumElts = getTypeSizeIndex(Value: C->getType()->getPrimitiveSizeInBits(),
2632 Ty: VecEltTy);
2633 // If the constant is the size of a vector element, we just need to bitcast
2634 // it to the right type so it gets properly inserted.
2635 if (NumElts == 1)
2636 return collectInsertionElements(V: ConstantExpr::getBitCast(C, Ty: VecEltTy),
2637 Shift, Elements, VecEltTy, isBigEndian);
2638
2639 // Okay, this is a constant that covers multiple elements. Slice it up into
2640 // pieces and insert each element-sized piece into the vector.
2641 if (!isa<IntegerType>(Val: C->getType()))
2642 C = ConstantExpr::getBitCast(C, Ty: IntegerType::get(C&: V->getContext(),
2643 NumBits: C->getType()->getPrimitiveSizeInBits()));
2644 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
2645 Type *ElementIntTy = IntegerType::get(C&: C->getContext(), NumBits: ElementSize);
2646
2647 for (unsigned i = 0; i != NumElts; ++i) {
2648 unsigned ShiftI = i * ElementSize;
2649 Constant *Piece = ConstantFoldBinaryInstruction(
2650 Opcode: Instruction::LShr, V1: C, V2: ConstantInt::get(Ty: C->getType(), V: ShiftI));
2651 if (!Piece)
2652 return false;
2653
2654 Piece = ConstantExpr::getTrunc(C: Piece, Ty: ElementIntTy);
2655 if (!collectInsertionElements(V: Piece, Shift: ShiftI + Shift, Elements, VecEltTy,
2656 isBigEndian))
2657 return false;
2658 }
2659 return true;
2660 }
2661
2662 if (!V->hasOneUse()) return false;
2663
2664 Instruction *I = dyn_cast<Instruction>(Val: V);
2665 if (!I) return false;
2666 switch (I->getOpcode()) {
2667 default: return false; // Unhandled case.
2668 case Instruction::BitCast:
2669 if (I->getOperand(i: 0)->getType()->isVectorTy())
2670 return false;
2671 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2672 isBigEndian);
2673 case Instruction::ZExt:
2674 if (!isMultipleOfTypeSize(
2675 Value: I->getOperand(i: 0)->getType()->getPrimitiveSizeInBits(),
2676 Ty: VecEltTy))
2677 return false;
2678 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2679 isBigEndian);
2680 case Instruction::Or:
2681 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2682 isBigEndian) &&
2683 collectInsertionElements(V: I->getOperand(i: 1), Shift, Elements, VecEltTy,
2684 isBigEndian);
2685 case Instruction::Shl: {
2686 // Must be shifting by a constant that is a multiple of the element size.
2687 ConstantInt *CI = dyn_cast<ConstantInt>(Val: I->getOperand(i: 1));
2688 if (!CI) return false;
2689 Shift += CI->getZExtValue();
2690 if (!isMultipleOfTypeSize(Value: Shift, Ty: VecEltTy)) return false;
2691 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2692 isBigEndian);
2693 }
2694
2695 }
2696}
2697
2698
2699/// If the input is an 'or' instruction, we may be doing shifts and ors to
2700/// assemble the elements of the vector manually.
2701/// Try to rip the code out and replace it with insertelements. This is to
2702/// optimize code like this:
2703///
2704/// %tmp37 = bitcast float %inc to i32
2705/// %tmp38 = zext i32 %tmp37 to i64
2706/// %tmp31 = bitcast float %inc5 to i32
2707/// %tmp32 = zext i32 %tmp31 to i64
2708/// %tmp33 = shl i64 %tmp32, 32
2709/// %ins35 = or i64 %tmp33, %tmp38
2710/// %tmp43 = bitcast i64 %ins35 to <2 x float>
2711///
2712/// Into two insertelements that do "buildvector{%inc, %inc5}".
2713static Value *optimizeIntegerToVectorInsertions(BitCastInst &CI,
2714 InstCombinerImpl &IC) {
2715 auto *DestVecTy = cast<FixedVectorType>(Val: CI.getType());
2716 Value *IntInput = CI.getOperand(i_nocapture: 0);
2717
2718 // if the int input is just an undef value do not try to optimize to vector
2719 // insertions as it will prevent undef propagation
2720 if (isa<UndefValue>(Val: IntInput))
2721 return nullptr;
2722
2723 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
2724 if (!collectInsertionElements(V: IntInput, Shift: 0, Elements,
2725 VecEltTy: DestVecTy->getElementType(),
2726 isBigEndian: IC.getDataLayout().isBigEndian()))
2727 return nullptr;
2728
2729 // If we succeeded, we know that all of the element are specified by Elements
2730 // or are zero if Elements has a null entry. Recast this as a set of
2731 // insertions.
2732 Value *Result = Constant::getNullValue(Ty: CI.getType());
2733 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
2734 if (!Elements[i]) continue; // Unset element.
2735
2736 Result = IC.Builder.CreateInsertElement(Vec: Result, NewElt: Elements[i],
2737 Idx: IC.Builder.getInt32(C: i));
2738 }
2739
2740 return Result;
2741}
2742
2743/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
2744/// vector followed by extract element. The backend tends to handle bitcasts of
2745/// vectors better than bitcasts of scalars because vector registers are
2746/// usually not type-specific like scalar integer or scalar floating-point.
2747static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast,
2748 InstCombinerImpl &IC) {
2749 Value *VecOp, *Index;
2750 if (!match(V: BitCast.getOperand(i_nocapture: 0),
2751 P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_Value(V&: Index)))))
2752 return nullptr;
2753
2754 // The bitcast must be to a vectorizable type, otherwise we can't make a new
2755 // type to extract from.
2756 Type *DestType = BitCast.getType();
2757 VectorType *VecType = cast<VectorType>(Val: VecOp->getType());
2758 if (VectorType::isValidElementType(ElemTy: DestType)) {
2759 auto *NewVecType = VectorType::get(ElementType: DestType, Other: VecType);
2760 auto *NewBC = IC.Builder.CreateBitCast(V: VecOp, DestTy: NewVecType, Name: "bc");
2761 return ExtractElementInst::Create(Vec: NewBC, Idx: Index);
2762 }
2763
2764 // Only solve DestType is vector to avoid inverse transform in visitBitCast.
2765 // bitcast (extractelement <1 x elt>, dest) -> bitcast(<1 x elt>, dest)
2766 auto *FixedVType = dyn_cast<FixedVectorType>(Val: VecType);
2767 if (DestType->isVectorTy() && FixedVType && FixedVType->getNumElements() == 1)
2768 return CastInst::Create(Instruction::BitCast, S: VecOp, Ty: DestType);
2769
2770 return nullptr;
2771}
2772
2773/// Change the type of a bitwise logic operation if we can eliminate a bitcast.
2774static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast,
2775 InstCombiner::BuilderTy &Builder) {
2776 Type *DestTy = BitCast.getType();
2777 BinaryOperator *BO;
2778
2779 if (!match(V: BitCast.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BO))) ||
2780 !BO->isBitwiseLogicOp())
2781 return nullptr;
2782
2783 // FIXME: This transform is restricted to vector types to avoid backend
2784 // problems caused by creating potentially illegal operations. If a fix-up is
2785 // added to handle that situation, we can remove this check.
2786 if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
2787 return nullptr;
2788
2789 if (DestTy->isFPOrFPVectorTy()) {
2790 Value *X, *Y;
2791 // bitcast(logic(bitcast(X), bitcast(Y))) -> bitcast'(logic(bitcast'(X), Y))
2792 if (match(V: BO->getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
2793 match(V: BO->getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: Y))))) {
2794 if (X->getType()->isFPOrFPVectorTy() &&
2795 Y->getType()->isIntOrIntVectorTy()) {
2796 Value *CastedOp =
2797 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy: Y->getType());
2798 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: Y);
2799 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
2800 }
2801 if (X->getType()->isIntOrIntVectorTy() &&
2802 Y->getType()->isFPOrFPVectorTy()) {
2803 Value *CastedOp =
2804 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy: X->getType());
2805 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: X);
2806 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
2807 }
2808 }
2809 return nullptr;
2810 }
2811
2812 if (!DestTy->isIntOrIntVectorTy())
2813 return nullptr;
2814
2815 Value *X;
2816 if (match(V: BO->getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
2817 X->getType() == DestTy && !isa<Constant>(Val: X)) {
2818 // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
2819 Value *CastedOp1 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy);
2820 return BinaryOperator::Create(Op: BO->getOpcode(), S1: X, S2: CastedOp1);
2821 }
2822
2823 if (match(V: BO->getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
2824 X->getType() == DestTy && !isa<Constant>(Val: X)) {
2825 // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
2826 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
2827 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: X);
2828 }
2829
2830 // Canonicalize vector bitcasts to come before vector bitwise logic with a
2831 // constant. This eases recognition of special constants for later ops.
2832 // Example:
2833 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
2834 Constant *C;
2835 if (match(V: BO->getOperand(i_nocapture: 1), P: m_Constant(C))) {
2836 // bitcast (logic X, C) --> logic (bitcast X, C')
2837 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
2838 Value *CastedC = Builder.CreateBitCast(V: C, DestTy);
2839 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: CastedC);
2840 }
2841
2842 return nullptr;
2843}
2844
2845/// Change the type of a select if we can eliminate a bitcast.
2846static Instruction *foldBitCastSelect(BitCastInst &BitCast,
2847 InstCombiner::BuilderTy &Builder) {
2848 Value *Cond, *TVal, *FVal;
2849 if (!match(V: BitCast.getOperand(i_nocapture: 0),
2850 P: m_OneUse(SubPattern: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: TVal), R: m_Value(V&: FVal)))))
2851 return nullptr;
2852
2853 // A vector select must maintain the same number of elements in its operands.
2854 Type *CondTy = Cond->getType();
2855 Type *DestTy = BitCast.getType();
2856
2857 auto *DestVecTy = dyn_cast<VectorType>(Val: DestTy);
2858
2859 if (auto *CondVTy = dyn_cast<VectorType>(Val: CondTy))
2860 if (!DestVecTy ||
2861 CondVTy->getElementCount() != DestVecTy->getElementCount())
2862 return nullptr;
2863
2864 auto *Sel = cast<Instruction>(Val: BitCast.getOperand(i_nocapture: 0));
2865 auto *SrcVecTy = dyn_cast<VectorType>(Val: TVal->getType());
2866
2867 if ((isa<Constant>(Val: TVal) || isa<Constant>(Val: FVal)) &&
2868 (!DestVecTy ||
2869 (SrcVecTy && ElementCount::isKnownLE(LHS: DestVecTy->getElementCount(),
2870 RHS: SrcVecTy->getElementCount())))) {
2871 // Avoid introducing select of vector (or select of vector with more
2872 // elements) until the backend can undo this transformation.
2873 Value *CastedTVal = Builder.CreateBitCast(V: TVal, DestTy);
2874 Value *CastedFVal = Builder.CreateBitCast(V: FVal, DestTy);
2875 return SelectInst::Create(C: Cond, S1: CastedTVal, S2: CastedFVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
2876 }
2877
2878 // FIXME: This transform is restricted from changing the select between
2879 // scalars and vectors to avoid backend problems caused by creating
2880 // potentially illegal operations. If a fix-up is added to handle that
2881 // situation, we can remove this check.
2882 if ((DestVecTy != nullptr) != (SrcVecTy != nullptr))
2883 return nullptr;
2884
2885 Value *X;
2886 if (match(V: TVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) && X->getType() == DestTy &&
2887 !isa<Constant>(Val: X)) {
2888 // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
2889 Value *CastedVal = Builder.CreateBitCast(V: FVal, DestTy);
2890 return SelectInst::Create(C: Cond, S1: X, S2: CastedVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
2891 }
2892
2893 if (match(V: FVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) && X->getType() == DestTy &&
2894 !isa<Constant>(Val: X)) {
2895 // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
2896 Value *CastedVal = Builder.CreateBitCast(V: TVal, DestTy);
2897 return SelectInst::Create(C: Cond, S1: CastedVal, S2: X, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
2898 }
2899
2900 return nullptr;
2901}
2902
2903/// Check if all users of CI are StoreInsts.
2904static bool hasStoreUsersOnly(CastInst &CI) {
2905 for (User *U : CI.users()) {
2906 if (!isa<StoreInst>(Val: U))
2907 return false;
2908 }
2909 return true;
2910}
2911
2912/// This function handles following case
2913///
2914/// A -> B cast
2915/// PHI
2916/// B -> A cast
2917///
2918/// All the related PHI nodes can be replaced by new PHI nodes with type A.
2919/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
2920Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
2921 PHINode *PN) {
2922 // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
2923 if (hasStoreUsersOnly(CI))
2924 return nullptr;
2925
2926 Value *Src = CI.getOperand(i_nocapture: 0);
2927 Type *SrcTy = Src->getType(); // Type B
2928 Type *DestTy = CI.getType(); // Type A
2929
2930 SmallVector<PHINode *, 4> PhiWorklist;
2931 SmallSetVector<PHINode *, 4> OldPhiNodes;
2932
2933 // Find all of the A->B casts and PHI nodes.
2934 // We need to inspect all related PHI nodes, but PHIs can be cyclic, so
2935 // OldPhiNodes is used to track all known PHI nodes, before adding a new
2936 // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
2937 PhiWorklist.push_back(Elt: PN);
2938 OldPhiNodes.insert(X: PN);
2939 while (!PhiWorklist.empty()) {
2940 auto *OldPN = PhiWorklist.pop_back_val();
2941 for (Value *IncValue : OldPN->incoming_values()) {
2942 if (isa<Constant>(Val: IncValue))
2943 continue;
2944
2945 if (auto *LI = dyn_cast<LoadInst>(Val: IncValue)) {
2946 // If there is a sequence of one or more load instructions, each loaded
2947 // value is used as address of later load instruction, bitcast is
2948 // necessary to change the value type, don't optimize it. For
2949 // simplicity we give up if the load address comes from another load.
2950 Value *Addr = LI->getOperand(i_nocapture: 0);
2951 if (Addr == &CI || isa<LoadInst>(Val: Addr))
2952 return nullptr;
2953 // Don't tranform "load <256 x i32>, <256 x i32>*" to
2954 // "load x86_amx, x86_amx*", because x86_amx* is invalid.
2955 // TODO: Remove this check when bitcast between vector and x86_amx
2956 // is replaced with a specific intrinsic.
2957 if (DestTy->isX86_AMXTy())
2958 return nullptr;
2959 if (LI->hasOneUse() && LI->isSimple())
2960 continue;
2961 // If a LoadInst has more than one use, changing the type of loaded
2962 // value may create another bitcast.
2963 return nullptr;
2964 }
2965
2966 if (auto *PNode = dyn_cast<PHINode>(Val: IncValue)) {
2967 if (OldPhiNodes.insert(X: PNode))
2968 PhiWorklist.push_back(Elt: PNode);
2969 continue;
2970 }
2971
2972 auto *BCI = dyn_cast<BitCastInst>(Val: IncValue);
2973 // We can't handle other instructions.
2974 if (!BCI)
2975 return nullptr;
2976
2977 // Verify it's a A->B cast.
2978 Type *TyA = BCI->getOperand(i_nocapture: 0)->getType();
2979 Type *TyB = BCI->getType();
2980 if (TyA != DestTy || TyB != SrcTy)
2981 return nullptr;
2982 }
2983 }
2984
2985 // Check that each user of each old PHI node is something that we can
2986 // rewrite, so that all of the old PHI nodes can be cleaned up afterwards.
2987 for (auto *OldPN : OldPhiNodes) {
2988 for (User *V : OldPN->users()) {
2989 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
2990 if (!SI->isSimple() || SI->getOperand(i_nocapture: 0) != OldPN)
2991 return nullptr;
2992 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
2993 // Verify it's a B->A cast.
2994 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
2995 Type *TyA = BCI->getType();
2996 if (TyA != DestTy || TyB != SrcTy)
2997 return nullptr;
2998 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
2999 // As long as the user is another old PHI node, then even if we don't
3000 // rewrite it, the PHI web we're considering won't have any users
3001 // outside itself, so it'll be dead.
3002 if (!OldPhiNodes.contains(key: PHI))
3003 return nullptr;
3004 } else {
3005 return nullptr;
3006 }
3007 }
3008 }
3009
3010 // For each old PHI node, create a corresponding new PHI node with a type A.
3011 SmallDenseMap<PHINode *, PHINode *> NewPNodes;
3012 for (auto *OldPN : OldPhiNodes) {
3013 Builder.SetInsertPoint(OldPN);
3014 PHINode *NewPN = Builder.CreatePHI(Ty: DestTy, NumReservedValues: OldPN->getNumOperands());
3015 NewPNodes[OldPN] = NewPN;
3016 }
3017
3018 // Fill in the operands of new PHI nodes.
3019 for (auto *OldPN : OldPhiNodes) {
3020 PHINode *NewPN = NewPNodes[OldPN];
3021 for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
3022 Value *V = OldPN->getOperand(i_nocapture: j);
3023 Value *NewV = nullptr;
3024 if (auto *C = dyn_cast<Constant>(Val: V)) {
3025 NewV = ConstantExpr::getBitCast(C, Ty: DestTy);
3026 } else if (auto *LI = dyn_cast<LoadInst>(Val: V)) {
3027 // Explicitly perform load combine to make sure no opposing transform
3028 // can remove the bitcast in the meantime and trigger an infinite loop.
3029 Builder.SetInsertPoint(LI);
3030 NewV = combineLoadToNewType(LI&: *LI, NewTy: DestTy);
3031 // Remove the old load and its use in the old phi, which itself becomes
3032 // dead once the whole transform finishes.
3033 replaceInstUsesWith(I&: *LI, V: PoisonValue::get(T: LI->getType()));
3034 eraseInstFromFunction(I&: *LI);
3035 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3036 NewV = BCI->getOperand(i_nocapture: 0);
3037 } else if (auto *PrevPN = dyn_cast<PHINode>(Val: V)) {
3038 NewV = NewPNodes[PrevPN];
3039 }
3040 assert(NewV);
3041 NewPN->addIncoming(V: NewV, BB: OldPN->getIncomingBlock(i: j));
3042 }
3043 }
3044
3045 // Traverse all accumulated PHI nodes and process its users,
3046 // which are Stores and BitcCasts. Without this processing
3047 // NewPHI nodes could be replicated and could lead to extra
3048 // moves generated after DeSSA.
3049 // If there is a store with type B, change it to type A.
3050
3051
3052 // Replace users of BitCast B->A with NewPHI. These will help
3053 // later to get rid off a closure formed by OldPHI nodes.
3054 Instruction *RetVal = nullptr;
3055 for (auto *OldPN : OldPhiNodes) {
3056 PHINode *NewPN = NewPNodes[OldPN];
3057 for (User *V : make_early_inc_range(Range: OldPN->users())) {
3058 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3059 assert(SI->isSimple() && SI->getOperand(0) == OldPN);
3060 Builder.SetInsertPoint(SI);
3061 auto *NewBC =
3062 cast<BitCastInst>(Val: Builder.CreateBitCast(V: NewPN, DestTy: SrcTy));
3063 SI->setOperand(i_nocapture: 0, Val_nocapture: NewBC);
3064 Worklist.push(I: SI);
3065 assert(hasStoreUsersOnly(*NewBC));
3066 }
3067 else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3068 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3069 Type *TyA = BCI->getType();
3070 assert(TyA == DestTy && TyB == SrcTy);
3071 (void) TyA;
3072 (void) TyB;
3073 Instruction *I = replaceInstUsesWith(I&: *BCI, V: NewPN);
3074 if (BCI == &CI)
3075 RetVal = I;
3076 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3077 assert(OldPhiNodes.contains(PHI));
3078 (void) PHI;
3079 } else {
3080 llvm_unreachable("all uses should be handled");
3081 }
3082 }
3083 }
3084
3085 return RetVal;
3086}
3087
3088/// Fold (bitcast (or (and (bitcast X to int), signmask), nneg Y) to fp) to
3089/// copysign((bitcast Y to fp), X)
3090static Value *foldCopySignIdioms(BitCastInst &CI,
3091 InstCombiner::BuilderTy &Builder,
3092 const SimplifyQuery &SQ) {
3093 Value *X, *Y;
3094 Type *FTy = CI.getType();
3095 if (!FTy->isFPOrFPVectorTy())
3096 return nullptr;
3097 if (!match(V: &CI, P: m_ElementWiseBitCast(Op: m_c_Or(
3098 L: m_And(L: m_ElementWiseBitCast(Op: m_Value(V&: X)), R: m_SignMask()),
3099 R: m_Value(V&: Y)))))
3100 return nullptr;
3101 if (X->getType() != FTy)
3102 return nullptr;
3103 if (!isKnownNonNegative(V: Y, SQ))
3104 return nullptr;
3105
3106 return Builder.CreateCopySign(LHS: Builder.CreateBitCast(V: Y, DestTy: FTy), RHS: X);
3107}
3108
3109Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
3110 // If the operands are integer typed then apply the integer transforms,
3111 // otherwise just apply the common ones.
3112 Value *Src = CI.getOperand(i_nocapture: 0);
3113 Type *SrcTy = Src->getType();
3114 Type *DestTy = CI.getType();
3115
3116 // Get rid of casts from one type to the same type. These are useless and can
3117 // be replaced by the operand.
3118 if (DestTy == Src->getType())
3119 return replaceInstUsesWith(I&: CI, V: Src);
3120
3121 if (isa<FixedVectorType>(Val: DestTy)) {
3122 if (isa<IntegerType>(Val: SrcTy)) {
3123 // If this is a cast from an integer to vector, check to see if the input
3124 // is a trunc or zext of a bitcast from vector. If so, we can replace all
3125 // the casts with a shuffle and (potentially) a bitcast.
3126 if (isa<TruncInst>(Val: Src) || isa<ZExtInst>(Val: Src)) {
3127 CastInst *SrcCast = cast<CastInst>(Val: Src);
3128 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(Val: SrcCast->getOperand(i_nocapture: 0)))
3129 if (isa<VectorType>(Val: BCIn->getOperand(i_nocapture: 0)->getType()))
3130 if (Instruction *I = optimizeVectorResizeWithIntegerBitCasts(
3131 InVal: BCIn->getOperand(i_nocapture: 0), DestTy: cast<VectorType>(Val: DestTy), IC&: *this))
3132 return I;
3133 }
3134
3135 // If the input is an 'or' instruction, we may be doing shifts and ors to
3136 // assemble the elements of the vector manually. Try to rip the code out
3137 // and replace it with insertelements.
3138 if (Value *V = optimizeIntegerToVectorInsertions(CI, IC&: *this))
3139 return replaceInstUsesWith(I&: CI, V);
3140 }
3141 }
3142
3143 if (FixedVectorType *SrcVTy = dyn_cast<FixedVectorType>(Val: SrcTy)) {
3144 if (SrcVTy->getNumElements() == 1) {
3145 // If our destination is not a vector, then make this a straight
3146 // scalar-scalar cast.
3147 if (!DestTy->isVectorTy()) {
3148 Value *Elem =
3149 Builder.CreateExtractElement(Vec: Src,
3150 Idx: Constant::getNullValue(Ty: Type::getInt32Ty(C&: CI.getContext())));
3151 return CastInst::Create(Instruction::BitCast, S: Elem, Ty: DestTy);
3152 }
3153
3154 // Otherwise, see if our source is an insert. If so, then use the scalar
3155 // component directly:
3156 // bitcast (inselt <1 x elt> V, X, 0) to <n x m> --> bitcast X to <n x m>
3157 if (auto *InsElt = dyn_cast<InsertElementInst>(Val: Src))
3158 return new BitCastInst(InsElt->getOperand(i_nocapture: 1), DestTy);
3159 }
3160
3161 // Convert an artificial vector insert into more analyzable bitwise logic.
3162 unsigned BitWidth = DestTy->getScalarSizeInBits();
3163 Value *X, *Y;
3164 uint64_t IndexC;
3165 if (match(V: Src, P: m_OneUse(SubPattern: m_InsertElt(Val: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X))),
3166 Elt: m_Value(V&: Y), Idx: m_ConstantInt(V&: IndexC)))) &&
3167 DestTy->isIntegerTy() && X->getType() == DestTy &&
3168 Y->getType()->isIntegerTy() && isDesirableIntType(BitWidth)) {
3169 // Adjust for big endian - the LSBs are at the high index.
3170 if (DL.isBigEndian())
3171 IndexC = SrcVTy->getNumElements() - 1 - IndexC;
3172
3173 // We only handle (endian-normalized) insert to index 0. Any other insert
3174 // would require a left-shift, so that is an extra instruction.
3175 if (IndexC == 0) {
3176 // bitcast (inselt (bitcast X), Y, 0) --> or (and X, MaskC), (zext Y)
3177 unsigned EltWidth = Y->getType()->getScalarSizeInBits();
3178 APInt MaskC = APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - EltWidth);
3179 Value *AndX = Builder.CreateAnd(LHS: X, RHS: MaskC);
3180 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
3181 return BinaryOperator::CreateOr(V1: AndX, V2: ZextY);
3182 }
3183 }
3184 }
3185
3186 if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Val: Src)) {
3187 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
3188 // a bitcast to a vector with the same # elts.
3189 Value *ShufOp0 = Shuf->getOperand(i_nocapture: 0);
3190 Value *ShufOp1 = Shuf->getOperand(i_nocapture: 1);
3191 auto ShufElts = cast<VectorType>(Val: Shuf->getType())->getElementCount();
3192 auto SrcVecElts = cast<VectorType>(Val: ShufOp0->getType())->getElementCount();
3193 if (Shuf->hasOneUse() && DestTy->isVectorTy() &&
3194 cast<VectorType>(Val: DestTy)->getElementCount() == ShufElts &&
3195 ShufElts == SrcVecElts) {
3196 BitCastInst *Tmp;
3197 // If either of the operands is a cast from CI.getType(), then
3198 // evaluating the shuffle in the casted destination's type will allow
3199 // us to eliminate at least one cast.
3200 if (((Tmp = dyn_cast<BitCastInst>(Val: ShufOp0)) &&
3201 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy) ||
3202 ((Tmp = dyn_cast<BitCastInst>(Val: ShufOp1)) &&
3203 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy)) {
3204 Value *LHS = Builder.CreateBitCast(V: ShufOp0, DestTy);
3205 Value *RHS = Builder.CreateBitCast(V: ShufOp1, DestTy);
3206 // Return a new shuffle vector. Use the same element ID's, as we
3207 // know the vector types match #elts.
3208 return new ShuffleVectorInst(LHS, RHS, Shuf->getShuffleMask());
3209 }
3210 }
3211
3212 // A bitcasted-to-scalar and byte/bit reversing shuffle is better recognized
3213 // as a byte/bit swap:
3214 // bitcast <N x i8> (shuf X, undef, <N, N-1,...0>) -> bswap (bitcast X)
3215 // bitcast <N x i1> (shuf X, undef, <N, N-1,...0>) -> bitreverse (bitcast X)
3216 if (DestTy->isIntegerTy() && ShufElts.getKnownMinValue() % 2 == 0 &&
3217 Shuf->hasOneUse() && Shuf->isReverse()) {
3218 unsigned IntrinsicNum = 0;
3219 if (DL.isLegalInteger(Width: DestTy->getScalarSizeInBits()) &&
3220 SrcTy->getScalarSizeInBits() == 8) {
3221 IntrinsicNum = Intrinsic::bswap;
3222 } else if (SrcTy->getScalarSizeInBits() == 1) {
3223 IntrinsicNum = Intrinsic::bitreverse;
3224 }
3225 if (IntrinsicNum != 0) {
3226 assert(ShufOp0->getType() == SrcTy && "Unexpected shuffle mask");
3227 assert(match(ShufOp1, m_Undef()) && "Unexpected shuffle op");
3228 Function *BswapOrBitreverse = Intrinsic::getOrInsertDeclaration(
3229 M: CI.getModule(), id: IntrinsicNum, Tys: DestTy);
3230 Value *ScalarX = Builder.CreateBitCast(V: ShufOp0, DestTy);
3231 return CallInst::Create(Func: BswapOrBitreverse, Args: {ScalarX});
3232 }
3233 }
3234 }
3235
3236 // Handle the A->B->A cast, and there is an intervening PHI node.
3237 if (PHINode *PN = dyn_cast<PHINode>(Val: Src))
3238 if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
3239 return I;
3240
3241 if (Instruction *I = canonicalizeBitCastExtElt(BitCast&: CI, IC&: *this))
3242 return I;
3243
3244 if (Instruction *I = foldBitCastBitwiseLogic(BitCast&: CI, Builder))
3245 return I;
3246
3247 if (Instruction *I = foldBitCastSelect(BitCast&: CI, Builder))
3248 return I;
3249
3250 if (Value *V = foldCopySignIdioms(CI, Builder, SQ: SQ.getWithInstruction(I: &CI)))
3251 return replaceInstUsesWith(I&: CI, V);
3252
3253 return commonCastTransforms(CI);
3254}
3255
3256Instruction *InstCombinerImpl::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
3257 return commonCastTransforms(CI);
3258}
3259