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 if (auto *Trunc = dyn_cast<TruncInst>(Val: I)) {
90 if (auto *NewTrunc = dyn_cast<TruncInst>(Val: Res)) {
91 if (Trunc->getType()->getScalarSizeInBits() <=
92 Ty->getScalarSizeInBits()) {
93 NewTrunc->setHasNoSignedWrap(Trunc->hasNoSignedWrap());
94 NewTrunc->setHasNoUnsignedWrap(Trunc->hasNoUnsignedWrap());
95 }
96 } else if (auto *NewZExt = dyn_cast<ZExtInst>(Val: Res)) {
97 if (Trunc->hasNoUnsignedWrap())
98 NewZExt->setNonNeg();
99 }
100 }
101 break;
102 case Instruction::Select: {
103 Value *True = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty, isSigned,
104 IC, Processed);
105 Value *False = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 2), Ty, isSigned,
106 IC, Processed);
107 Res = SelectInst::Create(C: I->getOperand(i: 0), S1: True, S2: False);
108 break;
109 }
110 case Instruction::PHI: {
111 PHINode *OPN = cast<PHINode>(Val: I);
112 PHINode *NPN = PHINode::Create(Ty, NumReservedValues: OPN->getNumIncomingValues());
113 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
114 Value *V = EvaluateInDifferentTypeImpl(V: OPN->getIncomingValue(i), Ty,
115 isSigned, IC, Processed);
116 NPN->addIncoming(V, BB: OPN->getIncomingBlock(i));
117 }
118 Res = NPN;
119 break;
120 }
121 case Instruction::FPToUI:
122 case Instruction::FPToSI:
123 Res = CastInst::Create(static_cast<Instruction::CastOps>(Opc),
124 S: I->getOperand(i: 0), Ty);
125 break;
126 case Instruction::Call:
127 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
128 switch (II->getIntrinsicID()) {
129 default:
130 llvm_unreachable("Unsupported call!");
131 case Intrinsic::vscale: {
132 Function *Fn = Intrinsic::getOrInsertDeclaration(
133 M: I->getModule(), id: Intrinsic::vscale, OverloadTys: {Ty});
134 Res = CallInst::Create(Ty: Fn->getFunctionType(), F: Fn);
135 break;
136 }
137 case Intrinsic::umin:
138 case Intrinsic::umax:
139 case Intrinsic::smin:
140 case Intrinsic::smax: {
141 Value *Op0 = EvaluateInDifferentTypeImpl(V: II->getArgOperand(i: 0), Ty,
142 isSigned, IC, Processed);
143 Value *Op1 = EvaluateInDifferentTypeImpl(V: II->getArgOperand(i: 1), Ty,
144 isSigned, IC, Processed);
145 Function *Fn = Intrinsic::getOrInsertDeclaration(
146 M: I->getModule(), id: II->getIntrinsicID(), OverloadTys: {Ty});
147 Res = CallInst::Create(Ty: Fn->getFunctionType(), Func: Fn, Args: {Op0, Op1});
148 break;
149 }
150 case Intrinsic::abs: {
151 Value *Arg = EvaluateInDifferentTypeImpl(V: II->getArgOperand(i: 0), Ty,
152 isSigned, IC, Processed);
153 Function *Fn = Intrinsic::getOrInsertDeclaration(
154 M: I->getModule(), id: II->getIntrinsicID(), OverloadTys: {Ty});
155 Res = CallInst::Create(Ty: Fn->getFunctionType(), Func: Fn,
156 Args: {Arg, ConstantInt::getFalse(Context&: I->getContext())});
157 break;
158 }
159 }
160 }
161 break;
162 case Instruction::ShuffleVector: {
163 auto *ScalarTy = cast<VectorType>(Val: Ty)->getElementType();
164 auto *VTy = cast<VectorType>(Val: I->getOperand(i: 0)->getType());
165 auto *FixedTy = VectorType::get(ElementType: ScalarTy, EC: VTy->getElementCount());
166 Value *Op0 = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 0), Ty: FixedTy,
167 isSigned, IC, Processed);
168 Value *Op1 = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty: FixedTy,
169 isSigned, IC, Processed);
170 Res = new ShuffleVectorInst(Op0, Op1,
171 cast<ShuffleVectorInst>(Val: I)->getShuffleMask());
172 break;
173 }
174 default:
175 // TODO: Can handle more cases here.
176 llvm_unreachable("Unreachable!");
177 }
178
179 Res->takeName(V: I);
180 Value *Result = IC.InsertNewInstWith(New: Res, Old: I->getIterator());
181 // There is no need in keeping track of the old value/new value relationship
182 // when we have only one user, we came have here from that user and no-one
183 // else cares.
184 if (!V->hasOneUse())
185 Processed[V] = Result;
186
187 return Result;
188}
189
190/// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns
191/// true for, actually insert the code to evaluate the expression.
192Value *InstCombinerImpl::EvaluateInDifferentType(Value *V, Type *Ty,
193 bool isSigned) {
194 EvaluatedMap Processed;
195 return EvaluateInDifferentTypeImpl(V, Ty, isSigned, IC&: *this, Processed);
196}
197
198Instruction::CastOps
199InstCombinerImpl::isEliminableCastPair(const CastInst *CI1,
200 const CastInst *CI2) {
201 Type *SrcTy = CI1->getSrcTy();
202 Type *MidTy = CI1->getDestTy();
203 Type *DstTy = CI2->getDestTy();
204
205 Instruction::CastOps firstOp = CI1->getOpcode();
206 Instruction::CastOps secondOp = CI2->getOpcode();
207 Type *SrcIntPtrTy =
208 SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr;
209 Type *DstIntPtrTy =
210 DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr;
211 unsigned Res = CastInst::isEliminableCastPair(firstOpcode: firstOp, secondOpcode: secondOp, SrcTy, MidTy,
212 DstTy, DL: &DL);
213
214 // We don't want to form an inttoptr or ptrtoint that converts to an integer
215 // type that differs from the pointer size.
216 if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
217 (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
218 Res = 0;
219
220 return Instruction::CastOps(Res);
221}
222
223/// Implement the transforms common to all CastInst visitors.
224Instruction *InstCombinerImpl::commonCastTransforms(CastInst &CI) {
225 Value *Src = CI.getOperand(i_nocapture: 0);
226 Type *Ty = CI.getType();
227
228 if (Value *Res =
229 simplifyCastInst(CastOpc: CI.getOpcode(), Op: Src, Ty, Q: SQ.getWithInstruction(I: &CI)))
230 return replaceInstUsesWith(I&: CI, V: Res);
231
232 // Try to eliminate a cast of a cast.
233 if (auto *CSrc = dyn_cast<CastInst>(Val: Src)) { // A->B->C cast
234 if (Instruction::CastOps NewOpc = isEliminableCastPair(CI1: CSrc, CI2: &CI)) {
235 // The first cast (CSrc) is eliminable so we need to fix up or replace
236 // the second cast (CI). CSrc will then have a good chance of being dead.
237 auto *Res = CastInst::Create(NewOpc, S: CSrc->getOperand(i_nocapture: 0), Ty);
238 // Point debug users of the dying cast to the new one.
239 if (CSrc->hasOneUse())
240 replaceAllDbgUsesWith(From&: *CSrc, To&: *Res, DomPoint&: CI, DT);
241 return Res;
242 }
243 }
244
245 if (auto *Sel = dyn_cast<SelectInst>(Val: Src)) {
246 // We are casting a select. Try to fold the cast into the select if the
247 // select does not have a compare instruction with matching operand types
248 // or the select is likely better done in a narrow type.
249 // Creating a select with operands that are different sizes than its
250 // condition may inhibit other folds and lead to worse codegen.
251 auto *Cmp = dyn_cast<CmpInst>(Val: Sel->getCondition());
252 if (!Cmp || Cmp->getOperand(i_nocapture: 0)->getType() != Sel->getType() ||
253 (CI.getOpcode() == Instruction::Trunc &&
254 shouldChangeType(From: CI.getSrcTy(), To: CI.getType()))) {
255
256 // If it's a bitcast involving vectors, make sure it has the same number
257 // of elements on both sides.
258 if (CI.getOpcode() != Instruction::BitCast ||
259 match(V: &CI, P: m_ElementWiseBitCast(Op: m_Value()))) {
260 if (Instruction *NV = FoldOpIntoSelect(Op&: CI, SI: Sel)) {
261 replaceAllDbgUsesWith(From&: *Sel, To&: *NV, DomPoint&: CI, DT);
262 return NV;
263 }
264 }
265 }
266 }
267
268 // If we are casting a PHI, then fold the cast into the PHI.
269 if (auto *PN = dyn_cast<PHINode>(Val: Src)) {
270 // Don't do this if it would create a PHI node with an illegal type from a
271 // legal type.
272 if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() ||
273 shouldChangeType(From: CI.getSrcTy(), To: CI.getType()))
274 if (Instruction *NV = foldOpIntoPhi(I&: CI, PN))
275 return NV;
276 }
277
278 // Canonicalize a unary shuffle after the cast if neither operation changes
279 // the size or element size of the input vector.
280 // TODO: We could allow size-changing ops if that doesn't harm codegen.
281 // cast (shuffle X, Mask) --> shuffle (cast X), Mask
282 Value *X;
283 ArrayRef<int> Mask;
284 if (match(V: Src, P: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: X), v2: m_Poison(), mask: m_Mask(Mask))))) {
285 // TODO: Allow scalable vectors?
286 auto *SrcTy = dyn_cast<FixedVectorType>(Val: X->getType());
287 auto *DestTy = dyn_cast<FixedVectorType>(Val: Ty);
288 if (SrcTy && DestTy &&
289 SrcTy->getNumElements() == DestTy->getNumElements() &&
290 SrcTy->getPrimitiveSizeInBits() == DestTy->getPrimitiveSizeInBits()) {
291 Value *CastX = Builder.CreateCast(Op: CI.getOpcode(), V: X, DestTy);
292 return new ShuffleVectorInst(CastX, Mask);
293 }
294 }
295
296 return nullptr;
297}
298
299namespace {
300
301/// Helper class for evaluating whether a value can be computed in a different
302/// type without changing its value. Used by cast simplification transforms.
303class TypeEvaluationHelper {
304public:
305 /// Return true if we can evaluate the specified expression tree as type Ty
306 /// instead of its larger type, and arrive with the same value.
307 /// This is used by code that tries to eliminate truncates.
308 [[nodiscard]] static bool canEvaluateTruncated(Value *V, Type *Ty,
309 InstCombinerImpl &IC,
310 Instruction *CxtI);
311
312 /// Determine if the specified value can be computed in the specified wider
313 /// type and produce the same low bits. If not, return false.
314 [[nodiscard]] static bool canEvaluateZExtd(Value *V, Type *Ty,
315 unsigned &BitsToClear,
316 InstCombinerImpl &IC,
317 Instruction *CxtI);
318
319 /// Return true if we can take the specified value and return it as type Ty
320 /// without inserting any new casts and without changing the value of the
321 /// common low bits.
322 [[nodiscard]] static bool canEvaluateSExtd(Value *V, Type *Ty);
323
324private:
325 /// Constants and extensions/truncates from the destination type are always
326 /// free to be evaluated in that type.
327 [[nodiscard]] static bool canAlwaysEvaluateInType(Value *V, Type *Ty);
328
329 /// Check if we traversed all the users of the multi-use values we've seen.
330 [[nodiscard]] bool allPendingVisited() const {
331 return llvm::all_of(Range: Pending,
332 P: [this](Value *V) { return Visited.contains(Val: V); });
333 }
334
335 /// A generic wrapper for canEvaluate* recursions to inject visitation
336 /// tracking and enforce correct multi-use value evaluations.
337 [[nodiscard]] bool
338 canEvaluate(Value *V, Type *Ty,
339 llvm::function_ref<bool(Value *, Type *Type)> Pred) {
340 if (canAlwaysEvaluateInType(V, Ty))
341 return true;
342
343 auto *I = dyn_cast<Instruction>(Val: V);
344
345 if (I == nullptr)
346 return false;
347
348 // We insert false by default to return false when we encounter user loops.
349 const auto [It, Inserted] = Visited.insert(KV: {V, false});
350
351 // There are three possible cases for us having information on this value
352 // in the Visited map:
353 // 1. We properly checked it and concluded that we can evaluate it (true)
354 // 2. We properly checked it and concluded that we can't (false)
355 // 3. We started to check it, but during the recursive traversal we came
356 // back to it.
357 //
358 // For cases 1 and 2, we can safely return the stored result. For case 3, we
359 // can potentially have a situation where we can evaluate recursive user
360 // chains, but that can be quite tricky to do properly and isntead, we
361 // return false.
362 //
363 // In any case, we should return whatever was there in the map to begin
364 // with.
365 if (!Inserted)
366 return It->getSecond();
367
368 // We can easily make a decision about single-user values whether they can
369 // be evaluated in a different type or not, we came from that user. This is
370 // not as simple for multi-user values.
371 //
372 // In general, we have the following case (inverted control-flow, users are
373 // at the top):
374 //
375 // Cast %A
376 // ____|
377 // /
378 // %A = Use %B, %C
379 // ________| |
380 // / |
381 // %B = Use %D |
382 // ________| |
383 // / |
384 // %D = Use %C |
385 // ________|___|
386 // /
387 // %C = ...
388 //
389 // In this case, when we check %A, %B and %D, we are confident that we can
390 // make the decision here and now, since we came from their only users.
391 //
392 // For %C, it is harder. We come there twice, and when we come the first
393 // time, it's hard to tell if we will visit the second user (technically
394 // it's not hard, but we might need a lot of repetitive checks with non-zero
395 // cost).
396 //
397 // In the case above, we are allowed to evaluate %C in different type
398 // because all of it users were part of the traversal.
399 //
400 // In the following case, however, we can't make this conclusion:
401 //
402 // Cast %A
403 // ____|
404 // /
405 // %A = Use %B, %C
406 // ________| |
407 // / |
408 // %B = Use %D |
409 // ________| |
410 // / |
411 // %D = Use %C |
412 // | |
413 // foo(%C) | | <- never traversing foo(%C)
414 // ________|___|
415 // /
416 // %C = ...
417 //
418 // In this case, we still can evaluate %C in a different type, but we'd need
419 // to create a copy of the original %C to be used in foo(%C). Such
420 // duplication might be not profitable.
421 //
422 // For this reason, we collect all users of the mult-user values and mark
423 // them as "pending" and defer this decision to the very end. When we are
424 // done and and ready to have a positive verdict, we should double-check all
425 // of the pending users and ensure that we visited them. allPendingVisited
426 // predicate checks exactly that.
427 if (!I->hasOneUse()) {
428 for (Use &U : I->uses()) {
429 // For most instructions, evaluating them in a different type will
430 // change the type of all operands. This is not the case for select
431 // conditions. Make sure we don't retain an extra use via the select
432 // condition.
433 if (isa<SelectInst>(Val: U.getUser()) && U.getOperandNo() == 0)
434 return false;
435
436 Pending.push_back(Elt: U.getUser());
437 }
438 }
439
440 const bool Result = Pred(V, Ty);
441 // We have to set result this way and not via It because Pred is recursive
442 // and it is very likely that we grew Visited and invalidated It.
443 Visited[V] = Result;
444 return Result;
445 }
446
447 /// Filter out values that we can not evaluate in the destination type for
448 /// free.
449 [[nodiscard]] bool canNotEvaluateInType(Value *V, Type *Ty);
450
451 [[nodiscard]] bool canEvaluateTruncatedImpl(Value *V, Type *Ty,
452 InstCombinerImpl &IC,
453 Instruction *CxtI);
454 [[nodiscard]] bool canEvaluateTruncatedPred(Value *V, Type *Ty,
455 InstCombinerImpl &IC,
456 Instruction *CxtI);
457 [[nodiscard]] bool canEvaluateZExtdImpl(Value *V, Type *Ty,
458 unsigned &BitsToClear,
459 InstCombinerImpl &IC,
460 Instruction *CxtI);
461 [[nodiscard]] bool canEvaluateSExtdImpl(Value *V, Type *Ty);
462 [[nodiscard]] bool canEvaluateSExtdPred(Value *V, Type *Ty);
463
464 /// A bookkeeping map to memorize an already made decision for a traversed
465 /// value.
466 SmallDenseMap<Value *, bool, 8> Visited;
467
468 /// A list of pending values to check in the end.
469 SmallVector<Value *, 8> Pending;
470};
471
472} // anonymous namespace
473
474/// Constants and extensions/truncates from the destination type are always
475/// free to be evaluated in that type. This is a helper for canEvaluate*.
476bool TypeEvaluationHelper::canAlwaysEvaluateInType(Value *V, Type *Ty) {
477 if (isa<Constant>(Val: V))
478 return match(V, P: m_ImmConstant());
479
480 Value *X;
481 if (match(V, P: m_ZExtOrSExt(Op: m_SpecificType(RefTy: Ty, V&: X))) ||
482 match(V, P: m_Trunc(Op: m_SpecificType(RefTy: Ty, V&: X))))
483 return true;
484
485 return false;
486}
487
488/// Filter out values that we can not evaluate in the destination type for free.
489/// This is a helper for canEvaluate*.
490bool TypeEvaluationHelper::canNotEvaluateInType(Value *V, Type *Ty) {
491 if (!isa<Instruction>(Val: V))
492 return true;
493 // We don't extend or shrink something that has multiple uses -- doing so
494 // would require duplicating the instruction which isn't profitable.
495 if (!V->hasOneUse())
496 return true;
497
498 return false;
499}
500
501/// Return true if we can evaluate the specified expression tree as type Ty
502/// instead of its larger type, and arrive with the same value.
503/// This is used by code that tries to eliminate truncates.
504///
505/// Ty will always be a type smaller than V. We should return true if trunc(V)
506/// can be computed by computing V in the smaller type. If V is an instruction,
507/// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
508/// makes sense if x and y can be efficiently truncated.
509///
510/// This function works on both vectors and scalars.
511///
512bool TypeEvaluationHelper::canEvaluateTruncated(Value *V, Type *Ty,
513 InstCombinerImpl &IC,
514 Instruction *CxtI) {
515 TypeEvaluationHelper TYH;
516 return TYH.canEvaluateTruncatedImpl(V, Ty, IC, CxtI) &&
517 // We need to check whether we visited all users of multi-user values,
518 // and we have to do it at the very end, outside of the recursion.
519 TYH.allPendingVisited();
520}
521
522bool TypeEvaluationHelper::canEvaluateTruncatedImpl(Value *V, Type *Ty,
523 InstCombinerImpl &IC,
524 Instruction *CxtI) {
525 return canEvaluate(V, Ty, Pred: [this, &IC, CxtI](Value *V, Type *Ty) {
526 return canEvaluateTruncatedPred(V, Ty, IC, CxtI);
527 });
528}
529
530bool TypeEvaluationHelper::canEvaluateTruncatedPred(Value *V, Type *Ty,
531 InstCombinerImpl &IC,
532 Instruction *CxtI) {
533 auto *I = cast<Instruction>(Val: V);
534 Type *OrigTy = V->getType();
535 switch (I->getOpcode()) {
536 case Instruction::Add:
537 case Instruction::Sub:
538 case Instruction::Mul:
539 case Instruction::And:
540 case Instruction::Or:
541 case Instruction::Xor:
542 // These operators can all arbitrarily be extended or truncated.
543 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
544 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
545
546 case Instruction::UDiv:
547 case Instruction::URem: {
548 // UDiv and URem can be truncated if all the truncated bits are zero.
549 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
550 uint32_t BitWidth = Ty->getScalarSizeInBits();
551 assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
552 APInt Mask = APInt::getBitsSetFrom(numBits: OrigBitWidth, loBit: BitWidth);
553 // Do not preserve the original context instruction. Simplifying div/rem
554 // based on later context may introduce a trap.
555 if (IC.MaskedValueIsZero(V: I->getOperand(i: 0), Mask, CxtI: I) &&
556 IC.MaskedValueIsZero(V: I->getOperand(i: 1), Mask, CxtI: I)) {
557 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
558 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
559 }
560 break;
561 }
562 case Instruction::Shl: {
563 // If we are truncating the result of this SHL, and if it's a shift of an
564 // inrange amount, we can always perform a SHL in a smaller type.
565 uint32_t BitWidth = Ty->getScalarSizeInBits();
566 KnownBits AmtKnownBits =
567 llvm::computeKnownBits(V: I->getOperand(i: 1), DL: IC.getDataLayout());
568 if (AmtKnownBits.getMaxValue().ult(RHS: BitWidth))
569 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
570 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
571 break;
572 }
573 case Instruction::LShr: {
574 // If this is a truncate of a logical shr, we can truncate it to a smaller
575 // lshr iff we know that the bits we would otherwise be shifting in are
576 // already zeros.
577 // TODO: It is enough to check that the bits we would be shifting in are
578 // zero - use AmtKnownBits.getMaxValue().
579 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
580 uint32_t BitWidth = Ty->getScalarSizeInBits();
581 KnownBits AmtKnownBits = IC.computeKnownBits(V: I->getOperand(i: 1), CxtI);
582 APInt MaxShiftAmt = AmtKnownBits.getMaxValue();
583 APInt ShiftedBits = APInt::getBitsSetFrom(numBits: OrigBitWidth, loBit: BitWidth);
584 if (MaxShiftAmt.ult(RHS: BitWidth)) {
585 // If the only user is a trunc then we can narrow the shift if any new
586 // MSBs are not going to be used.
587 if (auto *Trunc = dyn_cast<TruncInst>(Val: V->user_back())) {
588 auto DemandedBits = Trunc->getType()->getScalarSizeInBits();
589 if ((MaxShiftAmt + DemandedBits).ule(RHS: BitWidth))
590 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
591 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
592 }
593 if (IC.MaskedValueIsZero(V: I->getOperand(i: 0), Mask: ShiftedBits, CxtI))
594 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
595 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
596 }
597 break;
598 }
599 case Instruction::AShr: {
600 // If this is a truncate of an arithmetic shr, we can truncate it to a
601 // smaller ashr iff we know that all the bits from the sign bit of the
602 // original type and the sign bit of the truncate type are similar.
603 // TODO: It is enough to check that the bits we would be shifting in are
604 // similar to sign bit of the truncate type.
605 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
606 uint32_t BitWidth = Ty->getScalarSizeInBits();
607 KnownBits AmtKnownBits =
608 llvm::computeKnownBits(V: I->getOperand(i: 1), DL: IC.getDataLayout());
609 unsigned ShiftedBits = OrigBitWidth - BitWidth;
610 if (AmtKnownBits.getMaxValue().ult(RHS: BitWidth) &&
611 ShiftedBits < IC.ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI))
612 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
613 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
614 break;
615 }
616 case Instruction::Trunc:
617 // trunc(trunc(x)) -> trunc(x)
618 return true;
619 case Instruction::ZExt:
620 case Instruction::SExt:
621 // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
622 // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
623 return true;
624 case Instruction::Select: {
625 SelectInst *SI = cast<SelectInst>(Val: I);
626 return canEvaluateTruncatedImpl(V: SI->getTrueValue(), Ty, IC, CxtI) &&
627 canEvaluateTruncatedImpl(V: SI->getFalseValue(), Ty, IC, CxtI);
628 }
629 case Instruction::PHI: {
630 // We can change a phi if we can change all operands. Note that we never
631 // get into trouble with cyclic PHIs here because canEvaluate handles use
632 // chain loops.
633 PHINode *PN = cast<PHINode>(Val: I);
634 return llvm::all_of(
635 Range: PN->incoming_values(), P: [this, Ty, &IC, CxtI](Value *IncValue) {
636 return canEvaluateTruncatedImpl(V: IncValue, Ty, IC, CxtI);
637 });
638 }
639 case Instruction::FPToUI:
640 case Instruction::FPToSI: {
641 // If the integer type can hold the max FP value, it is safe to cast
642 // directly to that type. Otherwise, we may create poison via overflow
643 // that did not exist in the original code.
644 Type *InputTy = I->getOperand(i: 0)->getType()->getScalarType();
645 const fltSemantics &Semantics = InputTy->getFltSemantics();
646 uint32_t MinBitWidth = APFloatBase::semanticsIntSizeInBits(
647 Semantics, I->getOpcode() == Instruction::FPToSI);
648 return Ty->getScalarSizeInBits() >= MinBitWidth;
649 }
650 case Instruction::ShuffleVector:
651 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CxtI) &&
652 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CxtI);
653
654 case Instruction::Call: {
655 Value *AbsOp;
656 if (match(V: I, P: m_Intrinsic<Intrinsic::abs>(Ops: m_Value(V&: AbsOp), Ops: m_Value()))) {
657 if (IC.ComputeMaxSignificantBits(Op: AbsOp, CxtI) > Ty->getScalarSizeInBits())
658 return false;
659 return canEvaluateTruncatedImpl(V: AbsOp, Ty, IC, CxtI);
660 }
661 auto *MM = dyn_cast<MinMaxIntrinsic>(Val: I);
662 if (!MM)
663 return false;
664 // The min/max can be performed in the narrow type when each operand has
665 // zero high bits (for umin/umax) or enough sign bits (for smin/smax).
666 Value *Op0 = MM->getLHS();
667 Value *Op1 = MM->getRHS();
668 uint32_t BitWidth = Ty->getScalarSizeInBits();
669 if (MM->isSigned()) {
670 if (IC.ComputeMaxSignificantBits(Op: Op0, CxtI) > BitWidth ||
671 IC.ComputeMaxSignificantBits(Op: Op1, CxtI) > BitWidth)
672 break;
673 } else {
674 APInt Mask =
675 APInt::getBitsSetFrom(numBits: OrigTy->getScalarSizeInBits(), loBit: BitWidth);
676 if (!IC.MaskedValueIsZero(V: Op0, Mask, CxtI) ||
677 !IC.MaskedValueIsZero(V: Op1, Mask, CxtI))
678 break;
679 }
680 return canEvaluateTruncatedImpl(V: Op0, Ty, IC, CxtI) &&
681 canEvaluateTruncatedImpl(V: Op1, Ty, IC, CxtI);
682 }
683 default:
684 // TODO: Can handle more cases here.
685 break;
686 }
687
688 return false;
689}
690
691/// Given a vector that is bitcast to an integer, optionally logically
692/// right-shifted, and truncated, convert it to an extractelement.
693/// Example (big endian):
694/// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32
695/// --->
696/// extractelement <4 x i32> %X, 1
697static Instruction *foldVecTruncToExtElt(TruncInst &Trunc,
698 InstCombinerImpl &IC) {
699 Value *TruncOp = Trunc.getOperand(i_nocapture: 0);
700 Type *DestType = Trunc.getType();
701 if (!TruncOp->hasOneUse() || !isa<IntegerType>(Val: DestType))
702 return nullptr;
703
704 Value *VecInput = nullptr;
705 ConstantInt *ShiftVal = nullptr;
706 if (!match(V: TruncOp, P: m_CombineOr(Ps: m_BitCast(Op: m_Value(V&: VecInput)),
707 Ps: m_LShr(L: m_BitCast(Op: m_Value(V&: VecInput)),
708 R: m_ConstantInt(CI&: ShiftVal)))) ||
709 !isa<VectorType>(Val: VecInput->getType()))
710 return nullptr;
711
712 VectorType *VecType = cast<VectorType>(Val: VecInput->getType());
713 unsigned VecWidth = VecType->getPrimitiveSizeInBits();
714 unsigned DestWidth = DestType->getPrimitiveSizeInBits();
715 unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0;
716
717 if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0))
718 return nullptr;
719
720 // If the element type of the vector doesn't match the result type,
721 // bitcast it to a vector type that we can extract from.
722 unsigned NumVecElts = VecWidth / DestWidth;
723 if (VecType->getElementType() != DestType) {
724 VecType = FixedVectorType::get(ElementType: DestType, NumElts: NumVecElts);
725 VecInput = IC.Builder.CreateBitCast(V: VecInput, DestTy: VecType, Name: "bc");
726 }
727
728 unsigned Elt = ShiftAmount / DestWidth;
729 if (IC.getDataLayout().isBigEndian())
730 Elt = NumVecElts - 1 - Elt;
731
732 return ExtractElementInst::Create(Vec: VecInput, Idx: IC.Builder.getInt32(C: Elt));
733}
734
735/// Whenever an element is extracted from a vector, optionally shifted down, and
736/// then truncated, canonicalize by converting it to a bitcast followed by an
737/// extractelement.
738///
739/// Examples (little endian):
740/// trunc (extractelement <4 x i64> %X, 0) to i32
741/// --->
742/// extractelement <8 x i32> (bitcast <4 x i64> %X to <8 x i32>), i32 0
743///
744/// trunc (lshr (extractelement <4 x i32> %X, 0), 8) to i8
745/// --->
746/// extractelement <16 x i8> (bitcast <4 x i32> %X to <16 x i8>), i32 1
747static Instruction *foldVecExtTruncToExtElt(TruncInst &Trunc,
748 InstCombinerImpl &IC) {
749 Value *Src = Trunc.getOperand(i_nocapture: 0);
750 Type *SrcType = Src->getType();
751 Type *DstType = Trunc.getType();
752
753 // Only attempt this if we have simple aliasing of the vector elements.
754 // A badly fit destination size would result in an invalid cast.
755 unsigned SrcBits = SrcType->getScalarSizeInBits();
756 unsigned DstBits = DstType->getScalarSizeInBits();
757 unsigned TruncRatio = SrcBits / DstBits;
758 if ((SrcBits % DstBits) != 0)
759 return nullptr;
760
761 Value *VecOp;
762 ConstantInt *Cst;
763 const APInt *ShiftAmount = nullptr;
764 if (!match(V: Src, P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_ConstantInt(CI&: Cst)))) &&
765 !match(V: Src,
766 P: m_OneUse(SubPattern: m_LShr(L: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_ConstantInt(CI&: Cst)),
767 R: m_APInt(Res&: ShiftAmount)))))
768 return nullptr;
769
770 auto *VecOpTy = cast<VectorType>(Val: VecOp->getType());
771 auto VecElts = VecOpTy->getElementCount();
772
773 uint64_t BitCastNumElts = VecElts.getKnownMinValue() * TruncRatio;
774 // Make sure we don't overflow in the calculation of the new index.
775 // (VecOpIdx + 1) * TruncRatio should not overflow.
776 if (Cst->uge(Num: std::numeric_limits<uint64_t>::max() / TruncRatio))
777 return nullptr;
778 uint64_t VecOpIdx = Cst->getZExtValue();
779 uint64_t NewIdx = IC.getDataLayout().isBigEndian()
780 ? (VecOpIdx + 1) * TruncRatio - 1
781 : VecOpIdx * TruncRatio;
782
783 // Adjust index by the whole number of truncated elements.
784 if (ShiftAmount) {
785 // Check shift amount is in range and shifts a whole number of truncated
786 // elements.
787 if (ShiftAmount->uge(RHS: SrcBits) || ShiftAmount->urem(RHS: DstBits) != 0)
788 return nullptr;
789
790 uint64_t IdxOfs = ShiftAmount->udiv(RHS: DstBits).getZExtValue();
791 // IdxOfs is guaranteed to be less than TruncRatio, so we won't overflow in
792 // the adjustment.
793 assert(IdxOfs < TruncRatio &&
794 "IdxOfs is expected to be less than TruncRatio.");
795 NewIdx = IC.getDataLayout().isBigEndian() ? (NewIdx - IdxOfs)
796 : (NewIdx + IdxOfs);
797 }
798
799 assert(BitCastNumElts <= std::numeric_limits<uint32_t>::max() &&
800 "overflow 32-bits");
801
802 auto *BitCastTo =
803 VectorType::get(ElementType: DstType, NumElements: BitCastNumElts, Scalable: VecElts.isScalable());
804 Value *BitCast = IC.Builder.CreateBitCast(V: VecOp, DestTy: BitCastTo);
805 return ExtractElementInst::Create(Vec: BitCast, Idx: IC.Builder.getInt64(C: NewIdx));
806}
807
808/// Funnel/Rotate left/right may occur in a wider type than necessary because of
809/// type promotion rules. Try to narrow the inputs and convert to funnel shift.
810Instruction *InstCombinerImpl::narrowFunnelShift(TruncInst &Trunc) {
811 assert((isa<VectorType>(Trunc.getSrcTy()) ||
812 shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) &&
813 "Don't narrow to an illegal scalar type");
814
815 // Bail out on strange types. It is possible to handle some of these patterns
816 // even with non-power-of-2 sizes, but it is not a likely scenario.
817 Type *DestTy = Trunc.getType();
818 unsigned NarrowWidth = DestTy->getScalarSizeInBits();
819 unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
820 if (!isPowerOf2_32(Value: NarrowWidth))
821 return nullptr;
822
823 // First, find an or'd pair of opposite shifts:
824 // trunc (or (lshr ShVal0, ShAmt0), (shl ShVal1, ShAmt1))
825 BinaryOperator *Or0, *Or1;
826 if (!match(V: Trunc.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_Or(L: m_BinOp(I&: Or0), R: m_BinOp(I&: Or1)))))
827 return nullptr;
828
829 Value *ShVal0, *ShVal1, *ShAmt0, *ShAmt1;
830 if (!match(V: Or0, P: m_OneUse(SubPattern: m_LogicalShift(L: m_Value(V&: ShVal0), R: m_Value(V&: ShAmt0)))) ||
831 !match(V: Or1, P: m_OneUse(SubPattern: m_LogicalShift(L: m_Value(V&: ShVal1), R: m_Value(V&: ShAmt1)))) ||
832 Or0->getOpcode() == Or1->getOpcode())
833 return nullptr;
834
835 // Canonicalize to or(shl(ShVal0, ShAmt0), lshr(ShVal1, ShAmt1)).
836 if (Or0->getOpcode() == BinaryOperator::LShr) {
837 std::swap(a&: Or0, b&: Or1);
838 std::swap(a&: ShVal0, b&: ShVal1);
839 std::swap(a&: ShAmt0, b&: ShAmt1);
840 }
841 assert(Or0->getOpcode() == BinaryOperator::Shl &&
842 Or1->getOpcode() == BinaryOperator::LShr &&
843 "Illegal or(shift,shift) pair");
844
845 // Match the shift amount operands for a funnel/rotate pattern. This always
846 // matches a subtraction on the R operand.
847 auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
848 // The shift amounts may add up to the narrow bit width:
849 // (shl ShVal0, L) | (lshr ShVal1, Width - L)
850 // If this is a funnel shift (different operands are shifted), then the
851 // shift amount can not over-shift (create poison) in the narrow type.
852 unsigned MaxShiftAmountWidth = Log2_32(Value: NarrowWidth);
853 APInt HiBitMask = ~APInt::getLowBitsSet(numBits: WideWidth, loBitsSet: MaxShiftAmountWidth);
854 if (ShVal0 == ShVal1 || MaskedValueIsZero(V: L, Mask: HiBitMask))
855 if (match(V: R, P: m_OneUse(SubPattern: m_Sub(L: m_SpecificInt(V: Width), R: m_Specific(V: L)))))
856 return L;
857
858 // The following patterns currently only work for rotation patterns.
859 // TODO: Add more general funnel-shift compatible patterns.
860 if (ShVal0 != ShVal1)
861 return nullptr;
862
863 // The shift amount may be masked with negation:
864 // (shl ShVal0, (X & (Width - 1))) | (lshr ShVal1, ((-X) & (Width - 1)))
865 Value *X;
866 unsigned Mask = Width - 1;
867 if (match(V: L, P: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: Mask))) &&
868 match(V: R, P: m_And(L: m_Neg(V: m_Specific(V: X)), R: m_SpecificInt(V: Mask))))
869 return X;
870
871 // Same as above, but the shift amount may be extended after masking:
872 if (match(V: L, P: m_ZExt(Op: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: Mask)))) &&
873 match(V: R, P: m_ZExt(Op: m_And(L: m_Neg(V: m_Specific(V: X)), R: m_SpecificInt(V: Mask)))))
874 return X;
875
876 return nullptr;
877 };
878
879 Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth);
880 bool IsFshl = true; // Sub on LSHR.
881 if (!ShAmt) {
882 ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth);
883 IsFshl = false; // Sub on SHL.
884 }
885 if (!ShAmt)
886 return nullptr;
887
888 // The right-shifted value must have high zeros in the wide type (for example
889 // from 'zext', 'and' or 'shift'). High bits of the left-shifted value are
890 // truncated, so those do not matter.
891 APInt HiBitMask = APInt::getHighBitsSet(numBits: WideWidth, hiBitsSet: WideWidth - NarrowWidth);
892 if (!MaskedValueIsZero(V: ShVal1, Mask: HiBitMask, CxtI: &Trunc))
893 return nullptr;
894
895 // Adjust the width of ShAmt for narrowed funnel shift operation:
896 // - Zero-extend if ShAmt is narrower than the destination type.
897 // - Truncate if ShAmt is wider, discarding non-significant high-order bits.
898 // This prepares ShAmt for llvm.fshl.i8(trunc(ShVal), trunc(ShVal),
899 // zext/trunc(ShAmt)).
900 Value *NarrowShAmt = Builder.CreateZExtOrTrunc(V: ShAmt, DestTy);
901
902 Value *X, *Y;
903 X = Y = Builder.CreateTrunc(V: ShVal0, DestTy);
904 if (ShVal0 != ShVal1)
905 Y = Builder.CreateTrunc(V: ShVal1, DestTy);
906 Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
907 Function *F =
908 Intrinsic::getOrInsertDeclaration(M: Trunc.getModule(), id: IID, OverloadTys: DestTy);
909 return CallInst::Create(Func: F, Args: {X, Y, NarrowShAmt});
910}
911
912/// Try to narrow the width of math or bitwise logic instructions by pulling a
913/// truncate ahead of binary operators.
914Instruction *InstCombinerImpl::narrowBinOp(TruncInst &Trunc) {
915 Type *SrcTy = Trunc.getSrcTy();
916 Type *DestTy = Trunc.getType();
917 unsigned SrcWidth = SrcTy->getScalarSizeInBits();
918 unsigned DestWidth = DestTy->getScalarSizeInBits();
919
920 if (!isa<VectorType>(Val: SrcTy) && !shouldChangeType(From: SrcTy, To: DestTy))
921 return nullptr;
922
923 BinaryOperator *BinOp;
924 if (!match(V: Trunc.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BinOp))))
925 return nullptr;
926
927 Value *BinOp0 = BinOp->getOperand(i_nocapture: 0);
928 Value *BinOp1 = BinOp->getOperand(i_nocapture: 1);
929 switch (BinOp->getOpcode()) {
930 case Instruction::And:
931 case Instruction::Or:
932 case Instruction::Xor:
933 case Instruction::Add:
934 case Instruction::Sub:
935 case Instruction::Mul: {
936 Constant *C;
937 if (match(V: BinOp0, P: m_Constant(C))) {
938 // trunc (binop C, X) --> binop (trunc C', X)
939 Constant *NarrowC = ConstantExpr::getTrunc(C, Ty: DestTy);
940 Value *TruncX = Builder.CreateTrunc(V: BinOp1, DestTy);
941 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: NarrowC, S2: TruncX);
942 }
943 if (match(V: BinOp1, P: m_Constant(C))) {
944 // trunc (binop X, C) --> binop (trunc X, C')
945 Constant *NarrowC = ConstantExpr::getTrunc(C, Ty: DestTy);
946 Value *TruncX = Builder.CreateTrunc(V: BinOp0, DestTy);
947 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: TruncX, S2: NarrowC);
948 }
949 Value *X;
950 if (match(V: BinOp0, P: m_ZExtOrSExt(Op: m_SpecificType(RefTy: DestTy, V&: X)))) {
951 // trunc (binop (ext X), Y) --> binop X, (trunc Y)
952 Value *NarrowOp1 = Builder.CreateTrunc(V: BinOp1, DestTy);
953 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: X, S2: NarrowOp1);
954 }
955 if (match(V: BinOp1, P: m_ZExtOrSExt(Op: m_SpecificType(RefTy: DestTy, V&: X)))) {
956 // trunc (binop Y, (ext X)) --> binop (trunc Y), X
957 Value *NarrowOp0 = Builder.CreateTrunc(V: BinOp0, DestTy);
958 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: NarrowOp0, S2: X);
959 }
960 break;
961 }
962 case Instruction::LShr:
963 case Instruction::AShr: {
964 // trunc (*shr (trunc A), C) --> trunc(*shr A, C)
965 Value *A;
966 Constant *C;
967 if (match(V: BinOp0, P: m_Trunc(Op: m_Value(V&: A))) && match(V: BinOp1, P: m_Constant(C))) {
968 unsigned MaxShiftAmt = SrcWidth - DestWidth;
969 // If the shift is small enough, all zero/sign bits created by the shift
970 // are removed by the trunc.
971 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
972 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
973 auto *OldShift = cast<Instruction>(Val: Trunc.getOperand(i_nocapture: 0));
974 bool IsExact = OldShift->isExact();
975 if (Constant *ShAmt = ConstantFoldIntegerCast(C, DestTy: A->getType(),
976 /*IsSigned*/ true, DL)) {
977 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
978 Value *Shift =
979 OldShift->getOpcode() == Instruction::AShr
980 ? Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: OldShift->getName(), isExact: IsExact)
981 : Builder.CreateLShr(LHS: A, RHS: ShAmt, Name: OldShift->getName(), isExact: IsExact);
982 return CastInst::CreateTruncOrBitCast(S: Shift, Ty: DestTy);
983 }
984 }
985 }
986 break;
987 }
988 default: break;
989 }
990
991 if (Instruction *NarrowOr = narrowFunnelShift(Trunc))
992 return NarrowOr;
993
994 return nullptr;
995}
996
997/// Try to narrow the width of a splat shuffle. This could be generalized to any
998/// shuffle with a constant operand, but we limit the transform to avoid
999/// creating a shuffle type that targets may not be able to lower effectively.
1000static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
1001 InstCombiner::BuilderTy &Builder) {
1002 Value *Shuf = Trunc.getOperand(i_nocapture: 0), *ShufVec;
1003 ArrayRef<int> SplatMask;
1004 if (match(V: Shuf, P: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: ShufVec), v2: m_Poison(),
1005 mask: m_Mask(SplatMask)))) &&
1006 match(Mask: SplatMask, P: m_SplatMask()) &&
1007 ElementCount::isKnownGE(
1008 LHS: cast<VectorType>(Val: Shuf->getType())->getElementCount(),
1009 RHS: cast<VectorType>(Val: ShufVec->getType())->getElementCount())) {
1010 // trunc (shuf X, poison, SplatMask) --> shuf (trunc X), poison, SplatMask
1011 Type *NewTruncTy =
1012 ShufVec->getType()->getWithNewType(EltTy: Trunc.getType()->getScalarType());
1013 Value *NarrowOp = Builder.CreateTrunc(V: ShufVec, DestTy: NewTruncTy);
1014 return new ShuffleVectorInst(NarrowOp, SplatMask);
1015 }
1016
1017 return nullptr;
1018}
1019
1020/// Try to narrow the width of an insert element. This could be generalized for
1021/// any vector constant, but we limit the transform to insertion into poison to
1022/// avoid potential backend problems from unsupported insertion widths. This
1023/// could also be extended to handle the case of inserting a scalar constant
1024/// into a vector variable.
1025static Instruction *shrinkInsertElt(CastInst &Trunc,
1026 InstCombiner::BuilderTy &Builder) {
1027 Instruction::CastOps Opcode = Trunc.getOpcode();
1028 assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
1029 "Unexpected instruction for shrinking");
1030
1031 Value *Elt, *Index;
1032 if (match(V: Trunc.getOperand(i_nocapture: 0),
1033 P: m_OneUse(SubPattern: m_InsertElt(Val: m_Poison(), Elt: m_Value(V&: Elt), Idx: m_Value(V&: Index))))) {
1034 // trunc (inselt poison, X, Index) --> inselt poison, (trunc X), Index
1035 // fptrunc (inselt poison, X, Index) --> inselt poison, (fptrunc X), Index
1036 auto *NarrowPoison = PoisonValue::get(T: Trunc.getType());
1037 Value *NarrowOp =
1038 Builder.CreateCast(Op: Opcode, V: Elt, DestTy: Trunc.getType()->getScalarType());
1039 return InsertElementInst::Create(Vec: NarrowPoison, NewElt: NarrowOp, Idx: Index);
1040 }
1041
1042 return nullptr;
1043}
1044
1045Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
1046 if (Instruction *Result = commonCastTransforms(CI&: Trunc))
1047 return Result;
1048
1049 Value *Src = Trunc.getOperand(i_nocapture: 0);
1050 Type *DestTy = Trunc.getType(), *SrcTy = Src->getType();
1051 unsigned DestWidth = DestTy->getScalarSizeInBits();
1052 unsigned SrcWidth = SrcTy->getScalarSizeInBits();
1053
1054 // Attempt to truncate the entire input expression tree to the destination
1055 // type. Only do this if the dest type is a simple type, don't convert the
1056 // expression tree to something weird like i93 unless the source is also
1057 // strange.
1058 if ((DestTy->isVectorTy() || shouldChangeType(From: SrcTy, To: DestTy)) &&
1059 TypeEvaluationHelper::canEvaluateTruncated(V: Src, Ty: DestTy, IC&: *this, CxtI: &Trunc)) {
1060
1061 // If this cast is a truncate, evaluting in a different type always
1062 // eliminates the cast, so it is always a win.
1063 LLVM_DEBUG(
1064 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1065 " to avoid cast: "
1066 << Trunc << '\n');
1067 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: false);
1068 assert(Res->getType() == DestTy);
1069 return replaceInstUsesWith(I&: Trunc, V: Res);
1070 }
1071
1072 // For integer types, check if we can shorten the entire input expression to
1073 // DestWidth * 2, which won't allow removing the truncate, but reducing the
1074 // width may enable further optimizations, e.g. allowing for larger
1075 // vectorization factors.
1076 if (auto *DestITy = dyn_cast<IntegerType>(Val: DestTy)) {
1077 if (DestWidth * 2 < SrcWidth) {
1078 auto *NewDestTy = DestITy->getExtendedType();
1079 if (shouldChangeType(From: SrcTy, To: NewDestTy) &&
1080 TypeEvaluationHelper::canEvaluateTruncated(V: Src, Ty: NewDestTy, IC&: *this,
1081 CxtI: &Trunc)) {
1082 LLVM_DEBUG(
1083 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1084 " to reduce the width of operand of"
1085 << Trunc << '\n');
1086 Value *Res = EvaluateInDifferentType(V: Src, Ty: NewDestTy, isSigned: false);
1087 return new TruncInst(Res, DestTy);
1088 }
1089 }
1090 }
1091 Value *X;
1092 if (DestWidth == 1 &&
1093 (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) &&
1094 match(V: Src, P: m_Exact(SubPattern: m_Shr(L: m_Value(V&: X), R: m_Value()))))
1095 return new ICmpInst(ICmpInst::ICMP_NE, X, Constant::getNullValue(Ty: SrcTy));
1096
1097 // See if we can simplify any instructions used by the input whose sole
1098 // purpose is to compute bits we don't care about.
1099 if (SimplifyDemandedInstructionBits(Inst&: Trunc))
1100 return &Trunc;
1101
1102 if (DestWidth == 1) {
1103 Value *Zero = Constant::getNullValue(Ty: SrcTy);
1104
1105 const APInt *C1;
1106 Constant *C2;
1107 if (match(V: Src, P: m_OneUse(SubPattern: m_Shr(L: m_Shl(L: m_Power2(V&: C1), R: m_Value(V&: X)),
1108 R: m_ImmConstant(C&: C2))))) {
1109 // trunc ((C1 << X) >> C2) to i1 --> X == (C2-cttz(C1)), where C1 is pow2
1110 Constant *Log2C1 = ConstantInt::get(Ty: SrcTy, V: C1->exactLogBase2());
1111 Constant *CmpC = ConstantExpr::getSub(C1: C2, C2: Log2C1);
1112 return new ICmpInst(ICmpInst::ICMP_EQ, X, CmpC);
1113 }
1114
1115 if (match(V: Src, P: m_Shr(L: m_Value(V&: X), R: m_SpecificInt(V: SrcWidth - 1)))) {
1116 // trunc (ashr X, BW-1) to i1 --> icmp slt X, 0
1117 // trunc (lshr X, BW-1) to i1 --> icmp slt X, 0
1118 return new ICmpInst(ICmpInst::ICMP_SLT, X, Zero);
1119 }
1120
1121 Constant *C;
1122 if (match(V: Src, P: m_OneUse(SubPattern: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C))))) {
1123 // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
1124 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1125 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1126 Value *And = Builder.CreateAnd(LHS: X, RHS: MaskC);
1127 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1128 }
1129 if (match(V: Src, P: m_OneUse(SubPattern: m_c_Or(L: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C)),
1130 R: m_Deferred(V: X))))) {
1131 // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
1132 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1133 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1134 Value *And = Builder.CreateAnd(LHS: X, RHS: Builder.CreateOr(LHS: MaskC, RHS: One));
1135 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1136 }
1137
1138 {
1139 const APInt *C;
1140 if (match(V: Src, P: m_Shl(L: m_APInt(Res&: C), R: m_Value(V&: X))) && (*C)[0] == 1) {
1141 // trunc (C << X) to i1 --> X == 0, where C is odd
1142 return new ICmpInst(ICmpInst::Predicate::ICMP_EQ, X, Zero);
1143 }
1144 }
1145
1146 if (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) {
1147 Value *X, *Y;
1148 if (match(V: Src, P: m_Xor(L: m_Value(V&: X), R: m_Value(V&: Y))))
1149 return new ICmpInst(ICmpInst::ICMP_NE, X, Y);
1150 }
1151
1152 if (match(V: Src,
1153 P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::usub_sat>(Ops: m_One(), Ops: m_Value(V&: X)))))
1154 return new ICmpInst(ICmpInst::ICMP_EQ, X,
1155 ConstantInt::getNullValue(Ty: SrcTy));
1156 }
1157
1158 Value *A, *B;
1159 Constant *C;
1160
1161 // trunc(u/smin(zext(a) + zext(b), MAX)) --> uadd.sat(a, b)
1162 if (match(V: Src, P: m_OneUse(SubPattern: m_CombineOr(
1163 Ps: m_UMin(Op0: m_OneUse(SubPattern: m_Add(L: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: A)),
1164 R: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: B)))),
1165 Op1: m_SpecificInt(V: APInt::getMaxValue(numBits: DestWidth))),
1166 Ps: m_SMin(Op0: m_OneUse(SubPattern: m_Add(L: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: A)),
1167 R: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: B)))),
1168 Op1: m_SpecificInt(V: APInt::getMaxValue(numBits: DestWidth))))))) {
1169 return replaceInstUsesWith(
1170 I&: Trunc, V: Builder.CreateBinaryIntrinsic(ID: Intrinsic::uadd_sat, LHS: A, RHS: B));
1171 }
1172
1173 // trunc(smax(zext(a) - zext(b), 0)) --> usub.sat(a, b)
1174 if (match(V: Src,
1175 P: m_OneUse(SubPattern: m_SMax(Op0: m_OneUse(SubPattern: m_Sub(L: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: A)),
1176 R: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: B)))),
1177 Op1: m_Zero())))) {
1178 return replaceInstUsesWith(
1179 I&: Trunc, V: Builder.CreateBinaryIntrinsic(ID: Intrinsic::usub_sat, LHS: A, RHS: B));
1180 }
1181
1182 if (match(V: Src, P: m_LShr(L: m_SExt(Op: m_Value(V&: A)), R: m_Constant(C)))) {
1183 unsigned AWidth = A->getType()->getScalarSizeInBits();
1184 unsigned MaxShiftAmt = SrcWidth - std::max(a: DestWidth, b: AWidth);
1185 auto *OldSh = cast<Instruction>(Val: Src);
1186 bool IsExact = OldSh->isExact();
1187
1188 // If the shift is small enough, all zero bits created by the shift are
1189 // removed by the trunc.
1190 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
1191 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
1192 auto GetNewShAmt = [&](unsigned Width) {
1193 Constant *MaxAmt = ConstantInt::get(Ty: SrcTy, V: Width - 1, IsSigned: false);
1194 Constant *Cmp =
1195 ConstantFoldCompareInstOperands(Predicate: ICmpInst::ICMP_ULT, LHS: C, RHS: MaxAmt, DL);
1196 Constant *ShAmt = ConstantFoldSelectInstruction(Cond: Cmp, V1: C, V2: MaxAmt);
1197 return ConstantFoldCastOperand(Opcode: Instruction::Trunc, C: ShAmt, DestTy: A->getType(),
1198 DL);
1199 };
1200
1201 // trunc (lshr (sext A), C) --> ashr A, C
1202 if (A->getType() == DestTy) {
1203 Constant *ShAmt = GetNewShAmt(DestWidth);
1204 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
1205 return IsExact ? BinaryOperator::CreateExactAShr(V1: A, V2: ShAmt)
1206 : BinaryOperator::CreateAShr(V1: A, V2: ShAmt);
1207 }
1208 // The types are mismatched, so create a cast after shifting:
1209 // trunc (lshr (sext A), C) --> sext/trunc (ashr A, C)
1210 if (Src->hasOneUse()) {
1211 Constant *ShAmt = GetNewShAmt(AWidth);
1212 Value *Shift = Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: "", isExact: IsExact);
1213 return CastInst::CreateIntegerCast(S: Shift, Ty: DestTy, isSigned: true);
1214 }
1215 }
1216 // TODO: Mask high bits with 'and'.
1217 }
1218
1219 if (Instruction *I = narrowBinOp(Trunc))
1220 return I;
1221
1222 if (Instruction *I = shrinkSplatShuffle(Trunc, Builder))
1223 return I;
1224
1225 if (Instruction *I = shrinkInsertElt(Trunc, Builder))
1226 return I;
1227
1228 if (Src->hasOneUse() &&
1229 (isa<VectorType>(Val: SrcTy) || shouldChangeType(From: SrcTy, To: DestTy))) {
1230 // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
1231 // dest type is native and cst < dest size.
1232 if (match(V: Src, P: m_Shl(L: m_Value(V&: A), R: m_Constant(C))) &&
1233 !match(V: A, P: m_Shr(L: m_Value(), R: m_Constant()))) {
1234 // Skip shifts of shift by constants. It undoes a combine in
1235 // FoldShiftByConstant and is the extend in reg pattern.
1236 APInt Threshold = APInt(C->getType()->getScalarSizeInBits(), DestWidth);
1237 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULT, Threshold))) {
1238 Value *NewTrunc = Builder.CreateTrunc(V: A, DestTy, Name: A->getName() + ".tr");
1239 return BinaryOperator::Create(Op: Instruction::Shl, S1: NewTrunc,
1240 S2: ConstantExpr::getTrunc(C, Ty: DestTy));
1241 }
1242 }
1243 }
1244
1245 // trunc (select(icmp_ult(A, DestTy_umax+1), A, sext(icmp_sgt(A, 0)))) -->
1246 // trunc (smin(smax(0, A), DestTy_umax))
1247 if (SrcTy->isIntegerTy() && isPowerOf2_64(Value: SrcTy->getPrimitiveSizeInBits()) &&
1248 isPowerOf2_64(Value: DestTy->getPrimitiveSizeInBits()) &&
1249 match(V: Src, P: m_OneUse(SubPattern: m_Select(
1250 C: m_OneUse(SubPattern: m_SpecificICmp(MatchPred: ICmpInst::ICMP_ULT, L: m_Value(V&: A),
1251 R: m_Constant(C))),
1252 L: m_Deferred(V: A),
1253 R: m_OneUse(SubPattern: m_SExt(Op: m_OneUse(SubPattern: m_SpecificICmp(
1254 MatchPred: ICmpInst::ICMP_SGT, L: m_Deferred(V: A), R: m_Zero())))))))) {
1255 APInt UpperBound = C->getUniqueInteger();
1256 APInt TruncatedMax = APInt::getAllOnes(numBits: DestTy->getIntegerBitWidth());
1257 TruncatedMax = TruncatedMax.zext(width: UpperBound.getBitWidth());
1258 if (!UpperBound.isZero() && UpperBound - 1 == TruncatedMax) {
1259 Value *SMax = Builder.CreateIntrinsic(ID: Intrinsic::smax, OverloadTypes: {SrcTy},
1260 Args: {ConstantInt::get(Ty: SrcTy, V: 0), A});
1261 Value *SMin = Builder.CreateIntrinsic(
1262 ID: Intrinsic::smin, OverloadTypes: {SrcTy},
1263 Args: {SMax, ConstantInt::get(Ty: SrcTy, V: TruncatedMax)});
1264 return new TruncInst(SMin, DestTy);
1265 }
1266 }
1267
1268 if (Instruction *I = foldVecTruncToExtElt(Trunc, IC&: *this))
1269 return I;
1270
1271 if (Instruction *I = foldVecExtTruncToExtElt(Trunc, IC&: *this))
1272 return I;
1273
1274 // trunc (ctlz_i32(zext(A), B) --> add(ctlz_i16(A, B), C)
1275 if (match(V: Src, P: m_OneUse(SubPattern: m_Ctlz(Op0: m_ZExt(Op: m_Value(V&: A)), Op1: m_Value(V&: B))))) {
1276 unsigned AWidth = A->getType()->getScalarSizeInBits();
1277 if (AWidth == DestWidth && AWidth > Log2_32(Value: SrcWidth)) {
1278 Value *WidthDiff = ConstantInt::get(Ty: A->getType(), V: SrcWidth - AWidth);
1279 Value *NarrowCtlz =
1280 Builder.CreateIntrinsic(ID: Intrinsic::ctlz, OverloadTypes: {Trunc.getType()}, Args: {A, B});
1281 return BinaryOperator::CreateAdd(V1: NarrowCtlz, V2: WidthDiff);
1282 }
1283 }
1284
1285 if (match(V: Src, P: m_VScale())) {
1286 if (Trunc.getFunction() &&
1287 Trunc.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1288 Attribute Attr =
1289 Trunc.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1290 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
1291 if (Log2_32(Value: *MaxVScale) < DestWidth)
1292 return replaceInstUsesWith(I&: Trunc, V: Builder.CreateVScale(Ty: DestTy));
1293 }
1294 }
1295
1296 // trunc(scmp(x, y)) -> scmp(x, y) with a narrower result type.
1297 // trunc(ucmp(x, y)) -> ucmp(x, y) with a narrower result type.
1298 // scmp/ucmp produce only -1, 0, or 1, so any result type with at least 2
1299 // bits can represent every possible value and the truncation is lossless.
1300 if (DestWidth >= 2)
1301 if (auto *CI = dyn_cast<CmpIntrinsic>(Val: Src); CI && CI->hasOneUse())
1302 return replaceInstUsesWith(
1303 I&: Trunc, V: Builder.CreateIntrinsic(RetTy: DestTy, ID: CI->getIntrinsicID(),
1304 Args: {CI->getLHS(), CI->getRHS()}));
1305
1306 if (DestWidth == 1 &&
1307 (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) &&
1308 isKnownNonZero(V: Src, Q: SQ.getWithInstruction(I: &Trunc)))
1309 return replaceInstUsesWith(I&: Trunc, V: ConstantInt::getTrue(Ty: DestTy));
1310
1311 bool Changed = false;
1312 if (!Trunc.hasNoSignedWrap() &&
1313 ComputeMaxSignificantBits(Op: Src, CxtI: &Trunc) <= DestWidth) {
1314 Trunc.setHasNoSignedWrap(true);
1315 Changed = true;
1316 }
1317 if (!Trunc.hasNoUnsignedWrap() &&
1318 MaskedValueIsZero(V: Src, Mask: APInt::getBitsSetFrom(numBits: SrcWidth, loBit: DestWidth),
1319 CxtI: &Trunc)) {
1320 Trunc.setHasNoUnsignedWrap(true);
1321 Changed = true;
1322 }
1323
1324 const APInt *C1;
1325 Value *V1;
1326 // OP = { lshr, ashr }
1327 // trunc ( OP i8 C1, V1) to i1 -> icmp eq V1, log_2(C1) iff C1 is power of 2
1328 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_Power2(V&: C1), R: m_Value(V&: V1)))) {
1329 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1330 return new ICmpInst(ICmpInst::ICMP_EQ, V1, Right);
1331 }
1332
1333 // OP = { lshr, ashr }
1334 // trunc ( OP i8 C1, V1) to i1 -> icmp ult V1, log_2(C1 + 1) iff (C1 + 1) is
1335 // power of 2
1336 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_LowBitMask(V&: C1), R: m_Value(V&: V1)))) {
1337 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_one());
1338 return new ICmpInst(ICmpInst::ICMP_ULT, V1, Right);
1339 }
1340
1341 // OP = { lshr, ashr }
1342 // trunc ( OP i8 C1, V1) to i1 -> icmp ugt V1, cttz(C1) - 1 iff (C1) is
1343 // negative power of 2
1344 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_NegatedPower2(V&: C1), R: m_Value(V&: V1)))) {
1345 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1346 return new ICmpInst(ICmpInst::ICMP_UGE, V1, Right);
1347 }
1348
1349 return Changed ? &Trunc : nullptr;
1350}
1351
1352Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp,
1353 ZExtInst &Zext) {
1354 // If we are just checking for a icmp eq of a single bit and zext'ing it
1355 // to an integer, then shift the bit to the appropriate place and then
1356 // cast to integer to avoid the comparison.
1357
1358 // FIXME: This set of transforms does not check for extra uses and/or creates
1359 // an extra instruction (an optional final cast is not included
1360 // in the transform comments). We may also want to favor icmp over
1361 // shifts in cases of equal instructions because icmp has better
1362 // analysis in general (invert the transform).
1363
1364 const APInt *Op1CV;
1365 if (match(V: Cmp->getOperand(i_nocapture: 1), P: m_APInt(Res&: Op1CV))) {
1366
1367 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
1368 if (Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) {
1369 Value *In = Cmp->getOperand(i_nocapture: 0);
1370 Value *Sh = ConstantInt::get(Ty: In->getType(),
1371 V: In->getType()->getScalarSizeInBits() - 1);
1372 In = Builder.CreateLShr(LHS: In, RHS: Sh, Name: In->getName() + ".lobit");
1373 if (In->getType() != Zext.getType())
1374 In = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false /*ZExt*/);
1375
1376 return replaceInstUsesWith(I&: Zext, V: In);
1377 }
1378
1379 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
1380 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
1381 // zext (X != 0) to i32 --> X iff X has only the low bit set.
1382 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
1383
1384 if (Op1CV->isZero() && Cmp->isEquality()) {
1385 // Exactly 1 possible 1? But not the high-bit because that is
1386 // canonicalized to this form.
1387 KnownBits Known = computeKnownBits(V: Cmp->getOperand(i_nocapture: 0), CxtI: &Zext);
1388 APInt KnownZeroMask(~Known.Zero);
1389 uint32_t ShAmt = KnownZeroMask.logBase2();
1390 bool IsExpectShAmt = KnownZeroMask.isPowerOf2() &&
1391 (Zext.getType()->getScalarSizeInBits() != ShAmt + 1);
1392 if (IsExpectShAmt &&
1393 (Cmp->getOperand(i_nocapture: 0)->getType() == Zext.getType() ||
1394 Cmp->getPredicate() == ICmpInst::ICMP_NE || ShAmt == 0)) {
1395 Value *In = Cmp->getOperand(i_nocapture: 0);
1396 if (ShAmt) {
1397 // Perform a logical shr by shiftamt.
1398 // Insert the shift to put the result in the low bit.
1399 In = Builder.CreateLShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: ShAmt),
1400 Name: In->getName() + ".lobit");
1401 }
1402
1403 // Toggle the low bit for "X == 0".
1404 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1405 In = Builder.CreateXor(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: 1));
1406
1407 if (Zext.getType() == In->getType())
1408 return replaceInstUsesWith(I&: Zext, V: In);
1409
1410 Value *IntCast = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false);
1411 return replaceInstUsesWith(I&: Zext, V: IntCast);
1412 }
1413 }
1414 }
1415
1416 if (Cmp->isEquality()) {
1417 // Test if a bit is clear/set using a shifted-one mask:
1418 // zext (icmp eq (and X, (1 << ShAmt)), 0) --> and (lshr (not X), ShAmt), 1
1419 // zext (icmp ne (and X, (1 << ShAmt)), 0) --> and (lshr X, ShAmt), 1
1420 Value *X, *ShAmt;
1421 if (Cmp->hasOneUse() && match(V: Cmp->getOperand(i_nocapture: 1), P: m_ZeroInt()) &&
1422 match(V: Cmp->getOperand(i_nocapture: 0),
1423 P: m_OneUse(SubPattern: m_c_And(L: m_Shl(L: m_One(), R: m_Value(V&: ShAmt)), R: m_Value(V&: X))))) {
1424 auto *And = cast<BinaryOperator>(Val: Cmp->getOperand(i_nocapture: 0));
1425 Value *Shift = And->getOperand(i_nocapture: X == And->getOperand(i_nocapture: 0) ? 1 : 0);
1426 if (Zext.getType() == And->getType() ||
1427 Cmp->getPredicate() != ICmpInst::ICMP_EQ || Shift->hasOneUse()) {
1428 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1429 X = Builder.CreateNot(V: X);
1430 Value *Lshr = Builder.CreateLShr(LHS: X, RHS: ShAmt);
1431 Value *And1 =
1432 Builder.CreateAnd(LHS: Lshr, RHS: ConstantInt::get(Ty: X->getType(), V: 1));
1433 return replaceInstUsesWith(
1434 I&: Zext, V: Builder.CreateZExtOrTrunc(V: And1, DestTy: Zext.getType()));
1435 }
1436 }
1437 }
1438
1439 return nullptr;
1440}
1441
1442/// Determine if the specified value can be computed in the specified wider type
1443/// and produce the same low bits. If not, return false.
1444///
1445/// If this function returns true, it can also return a non-zero number of bits
1446/// (in BitsToClear) which indicates that the value it computes is correct for
1447/// the zero extend, but that the additional BitsToClear bits need to be zero'd
1448/// out. For example, to promote something like:
1449///
1450/// %B = trunc i64 %A to i32
1451/// %C = lshr i32 %B, 8
1452/// %E = zext i32 %C to i64
1453///
1454/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
1455/// set to 8 to indicate that the promoted value needs to have bits 24-31
1456/// cleared in addition to bits 32-63. Since an 'and' will be generated to
1457/// clear the top bits anyway, doing this has no extra cost.
1458///
1459/// This function works on both vectors and scalars.
1460bool TypeEvaluationHelper::canEvaluateZExtd(Value *V, Type *Ty,
1461 unsigned &BitsToClear,
1462 InstCombinerImpl &IC,
1463 Instruction *CxtI) {
1464 TypeEvaluationHelper TYH;
1465 return TYH.canEvaluateZExtdImpl(V, Ty, BitsToClear, IC, CxtI);
1466}
1467bool TypeEvaluationHelper::canEvaluateZExtdImpl(Value *V, Type *Ty,
1468 unsigned &BitsToClear,
1469 InstCombinerImpl &IC,
1470 Instruction *CxtI) {
1471 BitsToClear = 0;
1472 if (canAlwaysEvaluateInType(V, Ty))
1473 return true;
1474 // We stick to the one-user limit for the ZExt transform due to the fact
1475 // that this predicate returns two values: predicate result and BitsToClear.
1476 if (canNotEvaluateInType(V, Ty))
1477 return false;
1478
1479 auto *I = cast<Instruction>(Val: V);
1480 unsigned Tmp;
1481 switch (I->getOpcode()) {
1482 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
1483 case Instruction::SExt: // zext(sext(x)) -> sext(x).
1484 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
1485 return true;
1486 case Instruction::And:
1487 case Instruction::Or:
1488 case Instruction::Xor:
1489 case Instruction::Add:
1490 case Instruction::Sub:
1491 case Instruction::Mul:
1492 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI) ||
1493 !canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CxtI))
1494 return false;
1495 // These can all be promoted if neither operand has 'bits to clear'.
1496 if (BitsToClear == 0 && Tmp == 0)
1497 return true;
1498
1499 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1500 // other side, BitsToClear is ok.
1501 if (Tmp == 0 && I->isBitwiseLogicOp()) {
1502 // We use MaskedValueIsZero here for generality, but the case we care
1503 // about the most is constant RHS.
1504 unsigned VSize = V->getType()->getScalarSizeInBits();
1505 if (IC.MaskedValueIsZero(V: I->getOperand(i: 1),
1506 Mask: APInt::getHighBitsSet(numBits: VSize, hiBitsSet: BitsToClear),
1507 CxtI)) {
1508 // If this is an And instruction and all of the BitsToClear are
1509 // known to be zero we can reset BitsToClear.
1510 if (I->getOpcode() == Instruction::And)
1511 BitsToClear = 0;
1512 return true;
1513 }
1514 }
1515
1516 // Otherwise, we don't know how to analyze this BitsToClear case yet.
1517 return false;
1518
1519 case Instruction::Shl: {
1520 // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1521 // upper bits we can reduce BitsToClear by the shift amount.
1522 uint64_t ShiftAmt;
1523 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1524 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI))
1525 return false;
1526 BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1527 return true;
1528 }
1529 return false;
1530 }
1531 case Instruction::LShr: {
1532 // We can promote lshr(x, cst) if we can promote x. This requires the
1533 // ultimate 'and' to clear out the high zero bits we're clearing out though.
1534 uint64_t ShiftAmt;
1535 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1536 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI))
1537 return false;
1538 BitsToClear += ShiftAmt;
1539 if (BitsToClear > V->getType()->getScalarSizeInBits())
1540 BitsToClear = V->getType()->getScalarSizeInBits();
1541 return true;
1542 }
1543 // Cannot promote variable LSHR.
1544 return false;
1545 }
1546 case Instruction::Select:
1547 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CxtI) ||
1548 !canEvaluateZExtdImpl(V: I->getOperand(i: 2), Ty, BitsToClear, IC, CxtI) ||
1549 // TODO: If important, we could handle the case when the BitsToClear are
1550 // known zero in the disagreeing side.
1551 Tmp != BitsToClear)
1552 return false;
1553 return true;
1554
1555 case Instruction::PHI: {
1556 // We can change a phi if we can change all operands. Note that we never
1557 // get into trouble with cyclic PHIs here because we only consider
1558 // instructions with a single use.
1559 PHINode *PN = cast<PHINode>(Val: I);
1560 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i: 0), Ty, BitsToClear, IC,
1561 CxtI))
1562 return false;
1563 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1564 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i), Ty, BitsToClear&: Tmp, IC, CxtI) ||
1565 // TODO: If important, we could handle the case when the BitsToClear
1566 // are known zero in the disagreeing input.
1567 Tmp != BitsToClear)
1568 return false;
1569 return true;
1570 }
1571 case Instruction::Call:
1572 // llvm.vscale() can always be executed in larger type, because the
1573 // value is automatically zero-extended.
1574 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I))
1575 if (II->getIntrinsicID() == Intrinsic::vscale)
1576 return true;
1577 return false;
1578 default:
1579 // TODO: Can handle more cases here.
1580 return false;
1581 }
1582}
1583
1584Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
1585 // If this zero extend is only used by a truncate, let the truncate be
1586 // eliminated before we try to optimize this zext.
1587 if (Zext.hasOneUse() && isa<TruncInst>(Val: Zext.user_back()) &&
1588 !isa<Constant>(Val: Zext.getOperand(i_nocapture: 0)))
1589 return nullptr;
1590
1591 // If one of the common conversion will work, do it.
1592 if (Instruction *Result = commonCastTransforms(CI&: Zext))
1593 return Result;
1594
1595 if (auto *NewI = foldExtractionOfVectorDeinterleave(RootZExt&: Zext))
1596 return NewI;
1597
1598 Value *Src = Zext.getOperand(i_nocapture: 0);
1599 Type *SrcTy = Src->getType(), *DestTy = Zext.getType();
1600
1601 // zext nneg bool x -> 0
1602 if (SrcTy->isIntOrIntVectorTy(BitWidth: 1) && Zext.hasNonNeg())
1603 return replaceInstUsesWith(I&: Zext, V: Constant::getNullValue(Ty: Zext.getType()));
1604
1605 // Try to extend the entire expression tree to the wide destination type.
1606 unsigned BitsToClear;
1607 if (shouldChangeType(From: SrcTy, To: DestTy) &&
1608 TypeEvaluationHelper::canEvaluateZExtd(V: Src, Ty: DestTy, BitsToClear, IC&: *this,
1609 CxtI: &Zext)) {
1610 assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1611 "Can't clear more bits than in SrcTy");
1612
1613 // Okay, we can transform this! Insert the new expression now.
1614 LLVM_DEBUG(
1615 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1616 " to avoid zero extend: "
1617 << Zext << '\n');
1618 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: false);
1619 assert(Res->getType() == DestTy);
1620
1621 // Preserve debug values referring to Src if the zext is its last use.
1622 if (auto *SrcOp = dyn_cast<Instruction>(Val: Src))
1623 if (SrcOp->hasOneUse())
1624 replaceAllDbgUsesWith(From&: *SrcOp, To&: *Res, DomPoint&: Zext, DT);
1625
1626 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits() - BitsToClear;
1627 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1628
1629 // If the high bits are already filled with zeros, just replace this
1630 // cast with the result.
1631 if (MaskedValueIsZero(
1632 V: Res, Mask: APInt::getHighBitsSet(numBits: DestBitSize, hiBitsSet: DestBitSize - SrcBitsKept),
1633 CxtI: &Zext))
1634 return replaceInstUsesWith(I&: Zext, V: Res);
1635
1636 // We need to emit an AND to clear the high bits.
1637 Constant *C = ConstantInt::get(Ty: Res->getType(),
1638 V: APInt::getLowBitsSet(numBits: DestBitSize, loBitsSet: SrcBitsKept));
1639 return BinaryOperator::CreateAnd(V1: Res, V2: C);
1640 }
1641
1642 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1643 // types and if the sizes are just right we can convert this into a logical
1644 // 'and' which will be much cheaper than the pair of casts.
1645 if (auto *CSrc = dyn_cast<TruncInst>(Val: Src)) { // A->B->C cast
1646 // TODO: Subsume this into EvaluateInDifferentType.
1647
1648 // Get the sizes of the types involved. We know that the intermediate type
1649 // will be smaller than A or C, but don't know the relation between A and C.
1650 Value *A = CSrc->getOperand(i_nocapture: 0);
1651 unsigned SrcSize = A->getType()->getScalarSizeInBits();
1652 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1653 unsigned DstSize = DestTy->getScalarSizeInBits();
1654 // If we're actually extending zero bits, then if
1655 // SrcSize < DstSize: zext(a & mask)
1656 // SrcSize == DstSize: a & mask
1657 // SrcSize > DstSize: trunc(a) & mask
1658 if (SrcSize < DstSize) {
1659 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1660 Constant *AndConst = ConstantInt::get(Ty: A->getType(), V: AndValue);
1661 Value *And = Builder.CreateAnd(LHS: A, RHS: AndConst, Name: CSrc->getName() + ".mask");
1662 return new ZExtInst(And, DestTy);
1663 }
1664
1665 if (SrcSize == DstSize) {
1666 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1667 return BinaryOperator::CreateAnd(V1: A, V2: ConstantInt::get(Ty: A->getType(),
1668 V: AndValue));
1669 }
1670 if (SrcSize > DstSize) {
1671 Value *Trunc = Builder.CreateTrunc(V: A, DestTy);
1672 APInt AndValue(APInt::getLowBitsSet(numBits: DstSize, loBitsSet: MidSize));
1673 return BinaryOperator::CreateAnd(V1: Trunc,
1674 V2: ConstantInt::get(Ty: Trunc->getType(),
1675 V: AndValue));
1676 }
1677 }
1678
1679 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1680 return transformZExtICmp(Cmp, Zext);
1681
1682 Constant *C;
1683 Value *X;
1684 // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1685 Value *And;
1686 if (match(V: Src, P: m_OneUse(SubPattern: m_Xor(L: m_Value(V&: And), R: m_Constant(C)))) &&
1687 match(V: And, P: m_OneUse(SubPattern: m_And(L: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: X)),
1688 R: m_Specific(V: C))))) {
1689 Value *ZC = Builder.CreateZExt(V: C, DestTy);
1690 return BinaryOperator::CreateXor(V1: Builder.CreateAnd(LHS: X, RHS: ZC), V2: ZC);
1691 }
1692
1693 // zext(sub(0, trunc(X))) -> and(sub(0, X), mask)
1694 if (match(V: Src, P: m_Sub(L: m_Zero(), R: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: X))))) {
1695 APInt Mask = APInt::getLowBitsSet(numBits: DestTy->getScalarSizeInBits(),
1696 loBitsSet: SrcTy->getScalarSizeInBits());
1697 Value *Neg = Builder.CreateSub(LHS: ConstantInt::get(Ty: DestTy, V: 0), RHS: X);
1698 return BinaryOperator::CreateAnd(V1: Neg, V2: ConstantInt::get(Ty: DestTy, V: Mask));
1699 }
1700
1701 // If we are truncating, masking, and then zexting back to the original type,
1702 // that's just a mask. This is not handled by canEvaluateZextd if the
1703 // intermediate values have extra uses. This could be generalized further for
1704 // a non-constant mask operand.
1705 // zext (and (trunc X), C) --> and X, (zext C)
1706 if (match(V: Src, P: m_And(L: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: X)), R: m_Constant(C)))) {
1707 Value *ZextC = Builder.CreateZExt(V: C, DestTy);
1708 return BinaryOperator::CreateAnd(V1: X, V2: ZextC);
1709 }
1710
1711 Value *Y;
1712 if (match(V: Src, P: m_OneUse(SubPattern: m_c_BitwiseLogic(
1713 L: m_NUWTrunc(Op: m_SpecificType(RefTy: DestTy, V&: X)), R: m_Value(V&: Y))))) {
1714 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
1715 return BinaryOperator::Create(Op: cast<BinaryOperator>(Val: Src)->getOpcode(), S1: X,
1716 S2: ZextY);
1717 }
1718
1719 if (match(V: Src, P: m_VScale())) {
1720 if (Zext.getFunction() &&
1721 Zext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1722 Attribute Attr =
1723 Zext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1724 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
1725 unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
1726 if (Log2_32(Value: *MaxVScale) < TypeWidth)
1727 return replaceInstUsesWith(I&: Zext, V: Builder.CreateVScale(Ty: DestTy));
1728 }
1729 }
1730 }
1731
1732 if (!Zext.hasNonNeg()) {
1733 // If this zero extend is only used by a shift, add nneg flag.
1734 if (Zext.hasOneUse() &&
1735 SrcTy->getScalarSizeInBits() >
1736 Log2_64_Ceil(Value: DestTy->getScalarSizeInBits()) &&
1737 match(V: Zext.user_back(), P: m_Shift(L: m_Value(), R: m_Specific(V: &Zext)))) {
1738 Zext.setNonNeg();
1739 return &Zext;
1740 }
1741
1742 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Zext))) {
1743 Zext.setNonNeg();
1744 return &Zext;
1745 }
1746 }
1747
1748 return nullptr;
1749}
1750
1751/// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1752Instruction *InstCombinerImpl::transformSExtICmp(ICmpInst *Cmp,
1753 SExtInst &Sext) {
1754 Value *Op0 = Cmp->getOperand(i_nocapture: 0), *Op1 = Cmp->getOperand(i_nocapture: 1);
1755 ICmpInst::Predicate Pred = Cmp->getPredicate();
1756
1757 // Don't bother if Op1 isn't of vector or integer type.
1758 if (!Op1->getType()->isIntOrIntVectorTy())
1759 return nullptr;
1760
1761 if (Pred == ICmpInst::ICMP_SLT && match(V: Op1, P: m_ZeroInt())) {
1762 // sext (x <s 0) --> ashr x, 31 (all ones if negative)
1763 Value *Sh = ConstantInt::get(Ty: Op0->getType(),
1764 V: Op0->getType()->getScalarSizeInBits() - 1);
1765 Value *In = Builder.CreateAShr(LHS: Op0, RHS: Sh, Name: Op0->getName() + ".lobit");
1766 if (In->getType() != Sext.getType())
1767 In = Builder.CreateIntCast(V: In, DestTy: Sext.getType(), isSigned: true /*SExt*/);
1768
1769 return replaceInstUsesWith(I&: Sext, V: In);
1770 }
1771
1772 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Val: Op1)) {
1773 // If we know that only one bit of the LHS of the icmp can be set and we
1774 // have an equality comparison with zero or a power of 2, we can transform
1775 // the icmp and sext into bitwise/integer operations.
1776 if (Cmp->hasOneUse() &&
1777 Cmp->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1778 KnownBits Known = computeKnownBits(V: Op0, CxtI: &Sext);
1779
1780 APInt KnownZeroMask(~Known.Zero);
1781 if (KnownZeroMask.isPowerOf2()) {
1782 Value *In = Cmp->getOperand(i_nocapture: 0);
1783
1784 // If the icmp tests for a known zero bit we can constant fold it.
1785 if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1786 Value *V = Pred == ICmpInst::ICMP_NE ?
1787 ConstantInt::getAllOnesValue(Ty: Sext.getType()) :
1788 ConstantInt::getNullValue(Ty: Sext.getType());
1789 return replaceInstUsesWith(I&: Sext, V);
1790 }
1791
1792 if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1793 // sext ((x & 2^n) == 0) -> (x >> n) - 1
1794 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1795 unsigned ShiftAmt = KnownZeroMask.countr_zero();
1796 // Perform a right shift to place the desired bit in the LSB.
1797 if (ShiftAmt)
1798 In = Builder.CreateLShr(LHS: In,
1799 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1800
1801 // At this point "In" is either 1 or 0. Subtract 1 to turn
1802 // {1, 0} -> {0, -1}.
1803 In = Builder.CreateAdd(LHS: In,
1804 RHS: ConstantInt::getAllOnesValue(Ty: In->getType()),
1805 Name: "sext");
1806 } else {
1807 // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1808 // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1809 unsigned ShiftAmt = KnownZeroMask.countl_zero();
1810 // Perform a left shift to place the desired bit in the MSB.
1811 if (ShiftAmt)
1812 In = Builder.CreateShl(LHS: In,
1813 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1814
1815 // Distribute the bit over the whole bit width.
1816 In = Builder.CreateAShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(),
1817 V: KnownZeroMask.getBitWidth() - 1), Name: "sext");
1818 }
1819
1820 if (Sext.getType() == In->getType())
1821 return replaceInstUsesWith(I&: Sext, V: In);
1822 return CastInst::CreateIntegerCast(S: In, Ty: Sext.getType(), isSigned: true/*SExt*/);
1823 }
1824 }
1825 }
1826
1827 return nullptr;
1828}
1829
1830/// Return true if we can take the specified value and return it as type Ty
1831/// without inserting any new casts and without changing the value of the common
1832/// low bits. This is used by code that tries to promote integer operations to
1833/// a wider types will allow us to eliminate the extension.
1834///
1835/// This function works on both vectors and scalars.
1836///
1837bool TypeEvaluationHelper::canEvaluateSExtd(Value *V, Type *Ty) {
1838 TypeEvaluationHelper TYH;
1839 return TYH.canEvaluateSExtdImpl(V, Ty) && TYH.allPendingVisited();
1840}
1841
1842bool TypeEvaluationHelper::canEvaluateSExtdImpl(Value *V, Type *Ty) {
1843 return canEvaluate(V, Ty, Pred: [this](Value *V, Type *Ty) {
1844 return canEvaluateSExtdPred(V, Ty);
1845 });
1846}
1847
1848bool TypeEvaluationHelper::canEvaluateSExtdPred(Value *V, Type *Ty) {
1849 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
1850 "Can't sign extend type to a smaller type");
1851
1852 auto *I = cast<Instruction>(Val: V);
1853 switch (I->getOpcode()) {
1854 case Instruction::SExt: // sext(sext(x)) -> sext(x)
1855 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1856 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1857 return true;
1858 case Instruction::And:
1859 case Instruction::Or:
1860 case Instruction::Xor:
1861 case Instruction::Add:
1862 case Instruction::Sub:
1863 case Instruction::Mul:
1864 // These operators can all arbitrarily be extended if their inputs can.
1865 return canEvaluateSExtdImpl(V: I->getOperand(i: 0), Ty) &&
1866 canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty);
1867
1868 // case Instruction::Shl: TODO
1869 // case Instruction::LShr: TODO
1870
1871 case Instruction::Select:
1872 return canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty) &&
1873 canEvaluateSExtdImpl(V: I->getOperand(i: 2), Ty);
1874
1875 case Instruction::PHI: {
1876 // We can change a phi if we can change all operands. Note that we never
1877 // get into trouble with cyclic PHIs here because canEvaluate handles use
1878 // chain loops.
1879 PHINode *PN = cast<PHINode>(Val: I);
1880 for (Value *IncValue : PN->incoming_values())
1881 if (!canEvaluateSExtdImpl(V: IncValue, Ty))
1882 return false;
1883 return true;
1884 }
1885 default:
1886 // TODO: Can handle more cases here.
1887 break;
1888 }
1889
1890 return false;
1891}
1892
1893Instruction *InstCombinerImpl::visitSExt(SExtInst &Sext) {
1894 // If this sign extend is only used by a truncate, let the truncate be
1895 // eliminated before we try to optimize this sext.
1896 if (Sext.hasOneUse() && isa<TruncInst>(Val: Sext.user_back()))
1897 return nullptr;
1898
1899 if (Instruction *I = commonCastTransforms(CI&: Sext))
1900 return I;
1901
1902 Value *Src = Sext.getOperand(i_nocapture: 0);
1903 Type *SrcTy = Src->getType(), *DestTy = Sext.getType();
1904 unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1905 unsigned DestBitSize = DestTy->getScalarSizeInBits();
1906
1907 // If the value being extended is zero or positive, use a zext instead.
1908 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Sext))) {
1909 auto CI = CastInst::Create(Instruction::ZExt, S: Src, Ty: DestTy);
1910 CI->setNonNeg(true);
1911 return CI;
1912 }
1913
1914 // Try to extend the entire expression tree to the wide destination type.
1915 bool ShouldExtendExpression = true;
1916 Value *TruncSrc = nullptr;
1917 // It is not desirable to extend expression in the trunc + sext pattern when
1918 // destination type is narrower than original (pre-trunc) type.
1919 if (match(V: Src, P: m_Trunc(Op: m_Value(V&: TruncSrc))))
1920 if (TruncSrc->getType()->getScalarSizeInBits() > DestBitSize)
1921 ShouldExtendExpression = false;
1922 if (ShouldExtendExpression && shouldChangeType(From: SrcTy, To: DestTy) &&
1923 TypeEvaluationHelper::canEvaluateSExtd(V: Src, Ty: DestTy)) {
1924 // Okay, we can transform this! Insert the new expression now.
1925 LLVM_DEBUG(
1926 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1927 " to avoid sign extend: "
1928 << Sext << '\n');
1929 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: true);
1930 assert(Res->getType() == DestTy);
1931
1932 // If the high bits are already filled with sign bit, just replace this
1933 // cast with the result.
1934 if (ComputeNumSignBits(Op: Res, CxtI: &Sext) > DestBitSize - SrcBitSize)
1935 return replaceInstUsesWith(I&: Sext, V: Res);
1936
1937 // We need to emit a shl + ashr to do the sign extend.
1938 Value *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
1939 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: Res, RHS: ShAmt, Name: "sext"),
1940 V2: ShAmt);
1941 }
1942
1943 Value *X = TruncSrc;
1944 if (X) {
1945 // If the input has more sign bits than bits truncated, then convert
1946 // directly to final type.
1947 unsigned XBitSize = X->getType()->getScalarSizeInBits();
1948 bool HasNSW = cast<TruncInst>(Val: Src)->hasNoSignedWrap();
1949 if (HasNSW || (ComputeNumSignBits(Op: X, CxtI: &Sext) > XBitSize - SrcBitSize)) {
1950 auto *Res = CastInst::CreateIntegerCast(S: X, Ty: DestTy, /* isSigned */ true);
1951 if (auto *ResTrunc = dyn_cast<TruncInst>(Val: Res); ResTrunc && HasNSW)
1952 ResTrunc->setHasNoSignedWrap(true);
1953 return Res;
1954 }
1955
1956 // If input is a trunc from the destination type, then convert into shifts.
1957 if (Src->hasOneUse() && X->getType() == DestTy) {
1958 // sext (trunc X) --> ashr (shl X, C), C
1959 Constant *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
1960 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShAmt), V2: ShAmt);
1961 }
1962
1963 // If we are replacing shifted-in high zero bits with sign bits, convert
1964 // the logic shift to arithmetic shift and eliminate the cast to
1965 // intermediate type:
1966 // sext (trunc (lshr Y, C)) --> sext/trunc (ashr Y, C)
1967 Value *Y;
1968 if (Src->hasOneUse() &&
1969 match(V: X, P: m_LShr(L: m_Value(V&: Y),
1970 R: m_SpecificIntAllowPoison(V: XBitSize - SrcBitSize)))) {
1971 Value *Ashr = Builder.CreateAShr(LHS: Y, RHS: XBitSize - SrcBitSize);
1972 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
1973 }
1974 }
1975
1976 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1977 return transformSExtICmp(Cmp, Sext);
1978
1979 // If the input is a shl/ashr pair of a same constant, then this is a sign
1980 // extension from a smaller value. If we could trust arbitrary bitwidth
1981 // integers, we could turn this into a truncate to the smaller bit and then
1982 // use a sext for the whole extension. Since we don't, look deeper and check
1983 // for a truncate. If the source and dest are the same type, eliminate the
1984 // trunc and extend and just do shifts. For example, turn:
1985 // %a = trunc i32 %i to i8
1986 // %b = shl i8 %a, C
1987 // %c = ashr i8 %b, C
1988 // %d = sext i8 %c to i32
1989 // into:
1990 // %a = shl i32 %i, 32-(8-C)
1991 // %d = ashr i32 %a, 32-(8-C)
1992 Value *A = nullptr;
1993 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1994 Constant *BA = nullptr, *CA = nullptr;
1995 if (match(V: Src,
1996 P: m_AShr(L: m_Shl(L: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: A)), R: m_Constant(C&: BA)),
1997 R: m_ImmConstant(C&: CA))) &&
1998 BA->isElementWiseEqual(Y: CA)) {
1999 Constant *WideCurrShAmt =
2000 ConstantFoldCastOperand(Opcode: Instruction::SExt, C: CA, DestTy, DL);
2001 assert(WideCurrShAmt && "Constant folding of ImmConstant cannot fail");
2002 Constant *NumLowbitsLeft = ConstantExpr::getSub(
2003 C1: ConstantInt::get(Ty: DestTy, V: SrcTy->getScalarSizeInBits()), C2: WideCurrShAmt);
2004 Constant *NewShAmt = ConstantExpr::getSub(
2005 C1: ConstantInt::get(Ty: DestTy, V: DestTy->getScalarSizeInBits()),
2006 C2: NumLowbitsLeft);
2007 NewShAmt =
2008 Constant::mergeUndefsWith(C: Constant::mergeUndefsWith(C: NewShAmt, Other: BA), Other: CA);
2009 A = Builder.CreateShl(LHS: A, RHS: NewShAmt, Name: Sext.getName());
2010 return BinaryOperator::CreateAShr(V1: A, V2: NewShAmt);
2011 }
2012
2013 // Splatting a bit of constant-index across a value:
2014 // sext (ashr (trunc iN X to iM), M-1) to iN --> ashr (shl X, N-M), N-1
2015 // If the dest type is different, use a cast (adjust use check).
2016 if (match(V: Src, P: m_OneUse(SubPattern: m_AShr(L: m_Trunc(Op: m_Value(V&: X)),
2017 R: m_SpecificInt(V: SrcBitSize - 1))))) {
2018 Type *XTy = X->getType();
2019 unsigned XBitSize = XTy->getScalarSizeInBits();
2020 Constant *ShlAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - SrcBitSize);
2021 Constant *AshrAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - 1);
2022 if (XTy == DestTy)
2023 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShlAmtC),
2024 V2: AshrAmtC);
2025 if (cast<BinaryOperator>(Val: Src)->getOperand(i_nocapture: 0)->hasOneUse()) {
2026 Value *Ashr = Builder.CreateAShr(LHS: Builder.CreateShl(LHS: X, RHS: ShlAmtC), RHS: AshrAmtC);
2027 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
2028 }
2029 }
2030
2031 if (match(V: Src, P: m_VScale())) {
2032 if (Sext.getFunction() &&
2033 Sext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
2034 Attribute Attr =
2035 Sext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
2036 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
2037 if (Log2_32(Value: *MaxVScale) < (SrcBitSize - 1))
2038 return replaceInstUsesWith(I&: Sext, V: Builder.CreateVScale(Ty: DestTy));
2039 }
2040 }
2041
2042 // sext(scmp(x, y)) -> scmp(x, y) with a wider result type.
2043 // sext(ucmp(x, y)) -> ucmp(x, y) with a wider result type.
2044 // scmp/ucmp return only -1, 0, or 1, which sign-extend correctly to any
2045 // wider integer type, so we can sink the extension into the intrinsic.
2046 if (auto *CI = dyn_cast<CmpIntrinsic>(Val: Src); CI && CI->hasOneUse())
2047 return replaceInstUsesWith(
2048 I&: Sext, V: Builder.CreateIntrinsic(RetTy: DestTy, ID: CI->getIntrinsicID(),
2049 Args: {CI->getLHS(), CI->getRHS()}));
2050
2051 Value *Y;
2052 if (match(V: Src, P: m_OneUse(SubPattern: m_c_BitwiseLogic(
2053 L: m_NSWTrunc(Op: m_SpecificType(RefTy: DestTy, V&: X)), R: m_Value(V&: Y))))) {
2054 Value *SextY = Builder.CreateSExt(V: Y, DestTy);
2055 return BinaryOperator::Create(Op: cast<BinaryOperator>(Val: Src)->getOpcode(), S1: X,
2056 S2: SextY);
2057 }
2058
2059 return nullptr;
2060}
2061
2062/// Return a Constant* for the specified floating-point constant if it fits
2063/// in the specified FP type without changing its value.
2064static bool fitsInFPType(APFloat F, const fltSemantics &Sem) {
2065 bool losesInfo;
2066 (void)F.convert(ToSemantics: Sem, RM: APFloat::rmNearestTiesToEven, losesInfo: &losesInfo);
2067 return !losesInfo;
2068}
2069
2070static Type *shrinkFPConstant(LLVMContext &Ctx, const APFloat &F,
2071 bool PreferBFloat) {
2072 // See if the value can be truncated to bfloat and then reextended.
2073 if (PreferBFloat && fitsInFPType(F, Sem: APFloat::BFloat()))
2074 return Type::getBFloatTy(C&: Ctx);
2075 // See if the value can be truncated to half and then reextended.
2076 if (!PreferBFloat && fitsInFPType(F, Sem: APFloat::IEEEhalf()))
2077 return Type::getHalfTy(C&: Ctx);
2078 // See if the value can be truncated to float and then reextended.
2079 if (fitsInFPType(F, Sem: APFloat::IEEEsingle()))
2080 return Type::getFloatTy(C&: Ctx);
2081 if (&F.getSemantics() == &APFloat::IEEEdouble())
2082 return nullptr; // Won't shrink.
2083 // See if the value can be truncated to double and then reextended.
2084 if (fitsInFPType(F, Sem: APFloat::IEEEdouble()))
2085 return Type::getDoubleTy(C&: Ctx);
2086 // Don't try to shrink to various long double types.
2087 return nullptr;
2088}
2089
2090static Type *shrinkFPConstant(ConstantFP *CFP, bool PreferBFloat) {
2091 Type *Ty = CFP->getType();
2092 if (Ty->getScalarType()->isPPC_FP128Ty())
2093 return nullptr; // No constant folding of this.
2094
2095 Type *ShrinkTy =
2096 shrinkFPConstant(Ctx&: CFP->getContext(), F: CFP->getValueAPF(), PreferBFloat);
2097 if (ShrinkTy)
2098 if (auto *VecTy = dyn_cast<VectorType>(Val: Ty))
2099 ShrinkTy = VectorType::get(ElementType: ShrinkTy, Other: VecTy);
2100
2101 return ShrinkTy;
2102}
2103
2104// Determine if this is a vector of ConstantFPs and if so, return the minimal
2105// type we can safely truncate all elements to.
2106static Type *shrinkFPConstantVector(Value *V, bool PreferBFloat) {
2107 auto *CV = dyn_cast<Constant>(Val: V);
2108 auto *CVVTy = dyn_cast<FixedVectorType>(Val: V->getType());
2109 if (!CV || !CVVTy)
2110 return nullptr;
2111
2112 Type *MinType = nullptr;
2113
2114 unsigned NumElts = CVVTy->getNumElements();
2115
2116 // For fixed-width vectors we find the minimal type by looking
2117 // through the constant values of the vector.
2118 for (unsigned I = 0; I != NumElts; ++I) {
2119 if (match(V: CV->getAggregateElement(Elt: I), P: m_Poison()))
2120 continue;
2121
2122 auto *CFP = dyn_cast_or_null<ConstantFP>(Val: CV->getAggregateElement(Elt: I));
2123 if (!CFP)
2124 return nullptr;
2125
2126 Type *T = shrinkFPConstant(CFP, PreferBFloat);
2127 if (!T)
2128 return nullptr;
2129
2130 // If we haven't found a type yet or this type has a larger mantissa than
2131 // our previous type, this is our new minimal type.
2132 if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
2133 MinType = T;
2134 }
2135
2136 // Make a vector type from the minimal type.
2137 return MinType ? FixedVectorType::get(ElementType: MinType, NumElts) : nullptr;
2138}
2139
2140/// Find the minimum FP type we can safely truncate to.
2141static Type *getMinimumFPType(Value *V, Type *PreferredTy, InstCombiner &IC) {
2142 if (auto *FPExt = dyn_cast<FPExtInst>(Val: V))
2143 return FPExt->getOperand(i_nocapture: 0)->getType();
2144
2145 Value *Src;
2146 if (match(V, P: m_IToFP(Op: m_Value(V&: Src))) &&
2147 IC.canBeCastedExactlyIntToFP(V: Src, FPTy: PreferredTy, IsSigned: isa<SIToFPInst>(Val: V),
2148 CxtI: cast<Instruction>(Val: V)))
2149 return PreferredTy;
2150
2151 bool PreferBFloat = PreferredTy->getScalarType()->isBFloatTy();
2152 // If this value is a constant, return the constant in the smallest FP type
2153 // that can accurately represent it. This allows us to turn
2154 // (float)((double)X+2.0) into x+2.0f.
2155 if (auto *CFP = dyn_cast<ConstantFP>(Val: V))
2156 if (Type *T = shrinkFPConstant(CFP, PreferBFloat))
2157 return T;
2158
2159 // Try to shrink scalable and fixed splat vectors.
2160 if (auto *FPC = dyn_cast<Constant>(Val: V))
2161 if (auto *VTy = dyn_cast<VectorType>(Val: V->getType()))
2162 if (auto *Splat = dyn_cast_or_null<ConstantFP>(Val: FPC->getSplatValue()))
2163 if (Type *T = shrinkFPConstant(CFP: Splat, PreferBFloat))
2164 return VectorType::get(ElementType: T, Other: VTy);
2165
2166 // Try to shrink a vector of FP constants. This returns nullptr on scalable
2167 // vectors
2168 if (Type *T = shrinkFPConstantVector(V, PreferBFloat))
2169 return T;
2170
2171 return V->getType();
2172}
2173
2174bool InstCombiner::canBeCastedExactlyIntToFP(Value *V, Type *FPTy,
2175 bool IsSigned,
2176 const Instruction *CxtI) const {
2177 Type *SrcTy = V->getType();
2178 assert(SrcTy->isIntOrIntVectorTy() && "Expected an integer type");
2179 int SrcSize = (int)SrcTy->getScalarSizeInBits() - IsSigned;
2180 int DestNumSigBits = FPTy->getFPMantissaWidth();
2181
2182 // Easy case - if the source integer type has less bits than the FP mantissa,
2183 // then the cast must be exact.
2184 if (SrcSize <= DestNumSigBits)
2185 return true;
2186
2187 // Cast from FP to integer and back to FP is independent of the intermediate
2188 // integer width because of poison on overflow.
2189 Value *F;
2190 if (match(V, P: m_FPToI(Op: m_Value(V&: F)))) {
2191 // If this is uitofp (fptosi F), the source needs an extra bit to avoid
2192 // potential rounding of negative FP input values.
2193 int SrcNumSigBits = F->getType()->getFPMantissaWidth();
2194 if (!IsSigned && match(V, P: m_FPToSI(Op: m_Value())))
2195 SrcNumSigBits++;
2196
2197 // [su]itofp (fpto[su]i F) --> exact if the source type has less or equal
2198 // significant bits than the destination (and make sure neither type is
2199 // weird -- ppc_fp128).
2200 if (SrcNumSigBits > 0 && DestNumSigBits > 0 &&
2201 SrcNumSigBits <= DestNumSigBits)
2202 return true;
2203 }
2204
2205 // Try harder to find if the source integer type has less significant bits.
2206 // Compute number of sign bits or determine trailing zeros.
2207 KnownBits SrcKnown = computeKnownBits(V, CxtI);
2208 int SigBits = (int)SrcTy->getScalarSizeInBits() -
2209 SrcKnown.countMinLeadingZeros() -
2210 SrcKnown.countMinTrailingZeros();
2211 if (SigBits <= DestNumSigBits)
2212 return true;
2213
2214 // For sitofp, the sign maps to the FP sign bit, so only magnitude bits
2215 // (BitWidth - NumSignBits) consume mantissa.
2216 if (IsSigned) {
2217 SigBits = (int)SrcTy->getScalarSizeInBits() - ComputeNumSignBits(Op: V, CxtI);
2218 if (SigBits <= DestNumSigBits)
2219 return true;
2220 }
2221
2222 return false;
2223}
2224
2225bool InstCombiner::isKnownExactCastIntToFP(CastInst &I) const {
2226 CastInst::CastOps Opcode = I.getOpcode();
2227 assert((Opcode == CastInst::SIToFP || Opcode == CastInst::UIToFP) &&
2228 "Unexpected cast");
2229 Value *Src = I.getOperand(i_nocapture: 0);
2230 Type *FPTy = I.getType();
2231 return canBeCastedExactlyIntToFP(V: Src, FPTy, IsSigned: Opcode == CastInst::SIToFP, CxtI: &I);
2232}
2233
2234Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {
2235 if (Instruction *I = commonCastTransforms(CI&: FPT))
2236 return I;
2237
2238 // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
2239 // simplify this expression to avoid one or more of the trunc/extend
2240 // operations if we can do so without changing the numerical results.
2241 //
2242 // The exact manner in which the widths of the operands interact to limit
2243 // what we can and cannot do safely varies from operation to operation, and
2244 // is explained below in the various case statements.
2245 Type *Ty = FPT.getType();
2246 auto *BO = dyn_cast<BinaryOperator>(Val: FPT.getOperand(i_nocapture: 0));
2247 if (BO && BO->hasOneUse()) {
2248 Type *LHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 0), PreferredTy: Ty, IC&: *this);
2249 Type *RHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 1), PreferredTy: Ty, IC&: *this);
2250 unsigned OpWidth = BO->getType()->getFPMantissaWidth();
2251 unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
2252 unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
2253 unsigned SrcWidth = std::max(a: LHSWidth, b: RHSWidth);
2254 unsigned DstWidth = Ty->getFPMantissaWidth();
2255
2256 // Narrowing recomputes the binop in a smaller type, which can overflow to
2257 // inf where the wide op was finite. Therefore we can only keep ninf if
2258 // both the binop and the fptrunc have that flag.
2259 FastMathFlags NarrowFMF = BO->getFastMathFlags();
2260 NarrowFMF.setNoInfs(NarrowFMF.noInfs() && FPT.hasNoInfs());
2261
2262 switch (BO->getOpcode()) {
2263 default: break;
2264 case Instruction::FAdd:
2265 case Instruction::FSub:
2266 // For addition and subtraction, the infinitely precise result can
2267 // essentially be arbitrarily wide; proving that double rounding
2268 // will not occur because the result of OpI is exact (as we will for
2269 // FMul, for example) is hopeless. However, we *can* nonetheless
2270 // frequently know that double rounding cannot occur (or that it is
2271 // innocuous) by taking advantage of the specific structure of
2272 // infinitely-precise results that admit double rounding.
2273 //
2274 // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
2275 // to represent both sources, we can guarantee that the double
2276 // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
2277 // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
2278 // for proof of this fact).
2279 //
2280 // Note: Figueroa does not consider the case where DstFormat !=
2281 // SrcFormat. It's possible (likely even!) that this analysis
2282 // could be tightened for those cases, but they are rare (the main
2283 // case of interest here is (float)((double)float + float)).
2284 if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
2285 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2286 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2287 Instruction *RI = BinaryOperator::Create(Op: BO->getOpcode(), S1: LHS, S2: RHS);
2288 RI->setFastMathFlags(NarrowFMF);
2289 return RI;
2290 }
2291 break;
2292 case Instruction::FMul:
2293 // For multiplication, the infinitely precise result has at most
2294 // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
2295 // that such a value can be exactly represented, then no double
2296 // rounding can possibly occur; we can safely perform the operation
2297 // in the destination format if it can represent both sources.
2298 if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
2299 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2300 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2301 return BinaryOperator::CreateFMulFMF(V1: LHS, V2: RHS, FMF: NarrowFMF);
2302 }
2303 break;
2304 case Instruction::FDiv:
2305 // For division, we use again use the bound from Figueroa's
2306 // dissertation. I am entirely certain that this bound can be
2307 // tightened in the unbalanced operand case by an analysis based on
2308 // the diophantine rational approximation bound, but the well-known
2309 // condition used here is a good conservative first pass.
2310 // TODO: Tighten bound via rigorous analysis of the unbalanced case.
2311 if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
2312 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2313 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2314 return BinaryOperator::CreateFDivFMF(V1: LHS, V2: RHS, FMF: NarrowFMF);
2315 }
2316 break;
2317 case Instruction::FRem: {
2318 // Remainder is straightforward. Remainder is always exact, so the
2319 // type of OpI doesn't enter into things at all. We simply evaluate
2320 // in whichever source type is larger, then convert to the
2321 // destination type.
2322 if (SrcWidth == OpWidth)
2323 break;
2324 Value *LHS, *RHS;
2325 if (LHSWidth == SrcWidth) {
2326 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: LHSMinType);
2327 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: LHSMinType);
2328 } else {
2329 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: RHSMinType);
2330 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: RHSMinType);
2331 }
2332
2333 Value *ExactResult = Builder.CreateFRemFMF(L: LHS, R: RHS, FMFSource: BO);
2334 return CastInst::CreateFPCast(S: ExactResult, Ty);
2335 }
2336 }
2337 }
2338
2339 // (fptrunc (fneg x)) -> (fneg (fptrunc x))
2340 Value *X;
2341 Instruction *Op = dyn_cast<Instruction>(Val: FPT.getOperand(i_nocapture: 0));
2342 if (Op && Op->hasOneUse()) {
2343 FastMathFlags FMF = FPT.getFastMathFlags();
2344 if (auto *FPMO = dyn_cast<FPMathOperator>(Val: Op))
2345 FMF &= FPMO->getFastMathFlags();
2346
2347 if (match(V: Op, P: m_FNeg(X: m_Value(V&: X)))) {
2348 Value *InnerTrunc = Builder.CreateFPTruncFMF(V: X, DestTy: Ty, FMFSource: FMF);
2349 Value *Neg = Builder.CreateFNegFMF(V: InnerTrunc, FMFSource: FMF);
2350 return replaceInstUsesWith(I&: FPT, V: Neg);
2351 }
2352
2353 // If we are truncating a select that has an extended operand, we can
2354 // narrow the other operand and do the select as a narrow op.
2355 Value *Cond, *X, *Y;
2356 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_FPExt(Op: m_SpecificType(RefTy: Ty, V&: X)),
2357 R: m_Value(V&: Y)))) {
2358 // fptrunc (select Cond, (fpext X), Y --> select Cond, X, (fptrunc Y)
2359 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2360 Value *Sel =
2361 Builder.CreateSelectFMF(C: Cond, True: X, False: NarrowY, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2362 return replaceInstUsesWith(I&: FPT, V: Sel);
2363 }
2364 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: Y),
2365 R: m_FPExt(Op: m_SpecificType(RefTy: Ty, V&: X))))) {
2366 // fptrunc (select Cond, Y, (fpext X) --> select Cond, (fptrunc Y), X
2367 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2368 Value *Sel =
2369 Builder.CreateSelectFMF(C: Cond, True: NarrowY, False: X, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2370 return replaceInstUsesWith(I&: FPT, V: Sel);
2371 }
2372 }
2373
2374 if (auto *II = dyn_cast<IntrinsicInst>(Val: FPT.getOperand(i_nocapture: 0))) {
2375 switch (II->getIntrinsicID()) {
2376 default: break;
2377 case Intrinsic::ceil:
2378 case Intrinsic::fabs:
2379 case Intrinsic::floor:
2380 case Intrinsic::nearbyint:
2381 case Intrinsic::rint:
2382 case Intrinsic::round:
2383 case Intrinsic::roundeven:
2384 case Intrinsic::trunc: {
2385 Value *Src = II->getArgOperand(i: 0);
2386 if (!Src->hasOneUse())
2387 break;
2388
2389 // Except for fabs, this transformation requires the input of the unary FP
2390 // operation to be itself an fpext from the type to which we're
2391 // truncating.
2392 if (II->getIntrinsicID() != Intrinsic::fabs) {
2393 FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Val: Src);
2394 if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
2395 break;
2396 }
2397
2398 // Do unary FP operation on smaller type.
2399 // (fptrunc (fabs x)) -> (fabs (fptrunc x))
2400 Value *InnerTrunc = Builder.CreateFPTrunc(V: Src, DestTy: Ty);
2401 Function *Overload = Intrinsic::getOrInsertDeclaration(
2402 M: FPT.getModule(), id: II->getIntrinsicID(), OverloadTys: Ty);
2403 SmallVector<OperandBundleDef, 1> OpBundles;
2404 II->getOperandBundlesAsDefs(Defs&: OpBundles);
2405 CallInst *NewCI =
2406 CallInst::Create(Func: Overload, Args: {InnerTrunc}, Bundles: OpBundles, NameStr: II->getName());
2407 // A normal value may be converted to an infinity. It means that we cannot
2408 // propagate ninf from the intrinsic. So we propagate FMF from fptrunc.
2409 NewCI->copyFastMathFlags(I: &FPT);
2410 return NewCI;
2411 }
2412 }
2413 }
2414
2415 if (Instruction *I = shrinkInsertElt(Trunc&: FPT, Builder))
2416 return I;
2417
2418 Value *Src = FPT.getOperand(i_nocapture: 0);
2419 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2420 auto *FPCast = cast<CastInst>(Val: Src);
2421 if (isKnownExactCastIntToFP(I&: *FPCast))
2422 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2423 }
2424
2425 return nullptr;
2426}
2427
2428Instruction *InstCombinerImpl::visitFPExt(CastInst &FPExt) {
2429 // If the source operand is a cast from integer to FP and known exact, then
2430 // cast the integer operand directly to the destination type.
2431 Type *Ty = FPExt.getType();
2432 Value *Src = FPExt.getOperand(i_nocapture: 0);
2433 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2434 auto *FPCast = cast<CastInst>(Val: Src);
2435 if (isKnownExactCastIntToFP(I&: *FPCast))
2436 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2437 }
2438
2439 return commonCastTransforms(CI&: FPExt);
2440}
2441
2442/// fpto{s/u}i[.sat]({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
2443/// This is safe if the intermediate type has enough bits in its mantissa to
2444/// accurately represent all values of X. For example, this won't work with
2445/// i64 -> float -> i64.
2446template <typename FPToIntTy>
2447Instruction *InstCombinerImpl::foldItoFPtoI(FPToIntTy &FI) {
2448 constexpr bool IsSaturating = std::is_same_v<FPToIntTy, IntrinsicInst>;
2449
2450 if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
2451 return nullptr;
2452
2453 auto *OpI = cast<CastInst>(FI.getOperand(0));
2454 Value *X = OpI->getOperand(0);
2455 Type *XType = X->getType();
2456 Type *DestType = FI.getType();
2457 bool IsInputSigned = isa<SIToFPInst>(OpI);
2458
2459 bool IsOutputSigned;
2460 if constexpr (IsSaturating)
2461 IsOutputSigned = FI.getIntrinsicID() == Intrinsic::fptosi_sat;
2462 else
2463 IsOutputSigned = isa<FPToSIInst>(FI);
2464
2465 // Since we can assume the conversion won't overflow, our decision as to
2466 // whether the input will fit in the float should depend on the minimum
2467 // of the input range and output range.
2468
2469 // This means this is also safe for a signed input and unsigned output, since
2470 // a negative input would lead to undefined behavior.
2471 if (!isKnownExactCastIntToFP(I&: *OpI)) {
2472 if constexpr (!IsSaturating) {
2473 // The first cast may not round exactly based on the source integer width
2474 // and FP width, but the overflow UB rules can still allow this to fold.
2475 // If the destination type is narrow, that means the intermediate FP value
2476 // must be large enough to hold the source value exactly.
2477 //
2478 // For example, (uint8_t)((float)(uint32_t 16777217) is UB.
2479 int OutputSize = (int)DestType->getScalarSizeInBits();
2480 if (OutputSize > OpI->getType()->getFPMantissaWidth())
2481 return nullptr;
2482 } else {
2483 // Sat intrinsics produce a defined saturated value on overflow, so
2484 // the UB-based shortcut is invalid. Require exactness.
2485 return nullptr;
2486 }
2487 }
2488
2489 unsigned SrcWidth = XType->getScalarSizeInBits();
2490 unsigned DestWidth = DestType->getScalarSizeInBits();
2491
2492 if constexpr (IsSaturating) {
2493 // TODO: cross-sign and narrowing cases could be handled with range
2494 // analysis to prove the source fits in the destination.
2495 if (IsInputSigned != IsOutputSigned || DestWidth < SrcWidth)
2496 return nullptr;
2497 }
2498
2499 if (DestWidth > SrcWidth) {
2500 if (IsInputSigned && IsOutputSigned)
2501 return new SExtInst(X, DestType);
2502 return new ZExtInst(X, DestType);
2503 }
2504 if (DestWidth < SrcWidth)
2505 return new TruncInst(X, DestType);
2506
2507 assert(XType == DestType && "Unexpected types for int to FP to int casts");
2508 return replaceInstUsesWith(I&: FI, V: X);
2509}
2510
2511template Instruction *InstCombinerImpl::foldItoFPtoI<CastInst>(CastInst &);
2512template Instruction *
2513InstCombinerImpl::foldItoFPtoI<IntrinsicInst>(IntrinsicInst &);
2514
2515static Instruction *foldFPtoI(Instruction &FI, InstCombiner &IC) {
2516 // fpto{u/s}i non-norm --> 0
2517 FPClassTest Mask =
2518 FI.getOpcode() == Instruction::FPToUI ? fcPosNormal : fcNormal;
2519 KnownFPClass FPClass = computeKnownFPClass(
2520 V: FI.getOperand(i: 0), InterestedClasses: Mask, SQ: IC.getSimplifyQuery().getWithInstruction(I: &FI));
2521 if (FPClass.isKnownNever(Mask))
2522 return IC.replaceInstUsesWith(I&: FI, V: ConstantInt::getNullValue(Ty: FI.getType()));
2523
2524 // fpto{u/s}i (fdiv ({u/s}itofp X to F), C_fp) --> {u/s}div X, C
2525 //
2526 // F has precision p (significand bits incl. hidden bit); C_fp is the exact FP
2527 // value of the integer constant C. Given N = integer width, this is safe if:
2528 // Unsigned: C > 0 and N <= p.
2529 // Signed: C != 0 and N - 1 <= p, excluding (X == INT_MIN, C == -1) since
2530 // sdiv INT_MIN, -1 is UB while the FP path only yields poison.
2531 // fdiv X, -1 gets transformed to fneg in InstCombine regardless.
2532 //
2533 // The bounds make {u/s}itofp and C_fp exact (every |int| <= 2^p is exact),
2534 // and ensure the rounded quotient never crosses an integer boundary:
2535 // Rounding lemma: for 0 <= A <= 2^p, 1 <= B <= 2^p, q = floor(A/B),
2536 // trunc(R_p(A/B)) = q.
2537 // For r = A - qB > 0, m = q+1, half-gap H(m) <= q/2^p and
2538 // m - A/B = (B-r)/B >= 1/B > q/2^p >= H(m), so R_p(A/B) < m; q = 0 is
2539 // similar (H(1) = 2^(-p-1) < 2^-p <= 1/B).
2540 // Signed case: by symmetry R_p(-z) = -R_p(z), so fptosi yields s*q = sdiv.
2541 bool IsSigned = FI.getOpcode() == Instruction::FPToSI;
2542 Value *X;
2543 const APFloat *APF;
2544 if (IsSigned) {
2545 if (!match(V: FI.getOperand(i: 0),
2546 P: m_OneUse(SubPattern: m_FDiv(L: m_SIToFP(Op: m_Value(V&: X)), R: m_APFloat(Res&: APF)))))
2547 return nullptr;
2548 } else {
2549 if (!match(V: FI.getOperand(i: 0),
2550 P: m_OneUse(SubPattern: m_FDiv(L: m_UIToFP(Op: m_Value(V&: X)), R: m_APFloat(Res&: APF)))))
2551 return nullptr;
2552 }
2553 Type *IntTy = X->getType();
2554 if (FI.getType() != IntTy)
2555 return nullptr;
2556
2557 unsigned IntWidth = IntTy->getScalarSizeInBits();
2558 unsigned Precision = APFloat::semanticsPrecision(APF->getSemantics());
2559 if (Precision + IsSigned < IntWidth)
2560 return nullptr;
2561
2562 if (!APF->isInteger())
2563 return nullptr;
2564
2565 APSInt Divisor(IntWidth, !IsSigned);
2566 bool IsExact = false;
2567 APF->convertToInteger(Result&: Divisor, RM: APFloat::rmTowardZero, IsExact: &IsExact);
2568 if (!IsExact)
2569 return nullptr;
2570
2571 if (Divisor.isZero())
2572 return nullptr;
2573
2574 // sdiv INT_MIN, -1 is UB, not poison, so this isn't valid if X == INT_MIN.
2575 // fdiv X, -1 gets transformed to fneg anyways, so we do not handle C == -1.
2576 if (IsSigned && Divisor.isAllOnes())
2577 return nullptr;
2578
2579 Constant *C = ConstantInt::get(Ty: IntTy, V: Divisor);
2580 return IsSigned ? BinaryOperator::CreateSDiv(V1: X, V2: C)
2581 : BinaryOperator::CreateUDiv(V1: X, V2: C);
2582}
2583
2584Instruction *InstCombinerImpl::visitFPToUI(FPToUIInst &FI) {
2585 if (Instruction *I = foldItoFPtoI(FI))
2586 return I;
2587
2588 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2589 return I;
2590
2591 return commonCastTransforms(CI&: FI);
2592}
2593
2594Instruction *InstCombinerImpl::visitFPToSI(FPToSIInst &FI) {
2595 if (Instruction *I = foldItoFPtoI(FI))
2596 return I;
2597
2598 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2599 return I;
2600
2601 return commonCastTransforms(CI&: FI);
2602}
2603
2604Instruction *InstCombinerImpl::visitUIToFP(CastInst &CI) {
2605 if (Instruction *R = commonCastTransforms(CI))
2606 return R;
2607 if (!CI.hasNonNeg() && isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2608 CI.setNonNeg();
2609 return &CI;
2610 }
2611 return nullptr;
2612}
2613
2614Instruction *InstCombinerImpl::visitSIToFP(CastInst &CI) {
2615 if (Instruction *R = commonCastTransforms(CI))
2616 return R;
2617 if (isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2618 auto *UI =
2619 CastInst::Create(Instruction::UIToFP, S: CI.getOperand(i_nocapture: 0), Ty: CI.getType());
2620 UI->setNonNeg(true);
2621 return UI;
2622 }
2623 return nullptr;
2624}
2625
2626Instruction *InstCombinerImpl::visitIntToPtr(IntToPtrInst &CI) {
2627 // If the source integer type is not the intptr_t type for this target, do a
2628 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
2629 // cast to be exposed to other transforms.
2630 unsigned AS = CI.getAddressSpace();
2631 if (CI.getOperand(i_nocapture: 0)->getType()->getScalarSizeInBits() !=
2632 DL.getPointerSizeInBits(AS)) {
2633 Type *Ty = CI.getOperand(i_nocapture: 0)->getType()->getWithNewType(
2634 EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2635 Value *P = Builder.CreateZExtOrTrunc(V: CI.getOperand(i_nocapture: 0), DestTy: Ty);
2636 return new IntToPtrInst(P, CI.getType());
2637 }
2638
2639 // Replace (inttoptr (add (ptrtoint %Base), %Offset)) with
2640 // (getelementptr i8, %Base, %Offset) if the pointer is only used as integer
2641 // value.
2642 Value *Base;
2643 Value *Offset;
2644 auto UsesPointerAsInt = [](User *U) {
2645 if (isa<ICmpInst, PtrToIntInst>(Val: U))
2646 return true;
2647 if (auto *P = dyn_cast<PHINode>(Val: U))
2648 return P->hasOneUse() && isa<ICmpInst, PtrToIntInst>(Val: *P->user_begin());
2649 return false;
2650 };
2651 if (match(V: CI.getOperand(i_nocapture: 0),
2652 P: m_OneUse(SubPattern: m_c_Add(L: m_PtrToIntSameSize(DL, Op: m_Value(V&: Base)),
2653 R: m_Value(V&: Offset)))) &&
2654 CI.getType()->getPointerAddressSpace() ==
2655 Base->getType()->getPointerAddressSpace() &&
2656 all_of(Range: CI.users(), P: UsesPointerAsInt)) {
2657 return GetElementPtrInst::Create(PointeeType: Builder.getInt8Ty(), Ptr: Base, IdxList: Offset);
2658 }
2659
2660 if (Instruction *I = commonCastTransforms(CI))
2661 return I;
2662
2663 return nullptr;
2664}
2665
2666Value *InstCombinerImpl::foldPtrToIntOrAddrOfGEP(Type *IntTy, Value *Ptr) {
2667 // Look through chain of one-use GEPs.
2668 Type *PtrTy = Ptr->getType();
2669 SmallVector<GEPOperator *> GEPs;
2670 while (true) {
2671 auto *GEP = dyn_cast<GEPOperator>(Val: Ptr);
2672 if (!GEP || !GEP->hasOneUse())
2673 break;
2674 GEPs.push_back(Elt: GEP);
2675 Ptr = GEP->getPointerOperand();
2676 }
2677
2678 // Don't handle case where GEP converts from pointer to vector.
2679 if (GEPs.empty() || PtrTy != Ptr->getType())
2680 return nullptr;
2681
2682 // Check whether we know the integer value of the base pointer.
2683 Value *Res;
2684 Type *IdxTy = DL.getIndexType(PtrTy);
2685 if (match(V: Ptr, P: m_OneUse(SubPattern: m_IntToPtr(Op: m_Value(V&: Res)))) &&
2686 Res->getType() == IntTy && IntTy == IdxTy) {
2687 // pass
2688 } else if (isa<ConstantPointerNull>(Val: Ptr)) {
2689 Res = Constant::getNullValue(Ty: IdxTy);
2690 } else {
2691 return nullptr;
2692 }
2693
2694 // Perform the entire operation on integers instead.
2695 for (GEPOperator *GEP : reverse(C&: GEPs)) {
2696 Value *Offset = EmitGEPOffset(GEP);
2697 Res = Builder.CreateAdd(LHS: Res, RHS: Offset, Name: "", HasNUW: GEP->hasNoUnsignedWrap());
2698 }
2699 return Builder.CreateZExtOrTrunc(V: Res, DestTy: IntTy);
2700}
2701
2702Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
2703 // If the destination integer type is not the intptr_t type for this target,
2704 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
2705 // to be exposed to other transforms.
2706 Value *SrcOp = CI.getPointerOperand();
2707 Type *SrcTy = SrcOp->getType();
2708 Type *Ty = CI.getType();
2709 unsigned AS = CI.getPointerAddressSpace();
2710 unsigned TySize = Ty->getScalarSizeInBits();
2711 unsigned PtrSize = DL.getPointerSizeInBits(AS);
2712 if (TySize != PtrSize) {
2713 Type *IntPtrTy =
2714 SrcTy->getWithNewType(EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2715 Value *P = Builder.CreatePtrToInt(V: SrcOp, DestTy: IntPtrTy);
2716 return CastInst::CreateIntegerCast(S: P, Ty, /*isSigned=*/false);
2717 }
2718
2719 // (ptrtoint (ptrmask P, M))
2720 // -> (and (ptrtoint P), M)
2721 // This is generally beneficial as `and` is better supported than `ptrmask`.
2722 Value *Ptr, *Mask;
2723 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(
2724 Ops: m_Value(V&: Ptr), Ops: m_SpecificType(RefTy: Ty, V&: Mask)))))
2725 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToInt(V: Ptr, DestTy: Ty), V2: Mask);
2726
2727 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2728 return replaceInstUsesWith(I&: CI, V);
2729
2730 Value *Vec, *Scalar, *Index;
2731 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_InsertElt(Val: m_IntToPtr(Op: m_SpecificType(RefTy: Ty, V&: Vec)),
2732 Elt: m_Value(V&: Scalar), Idx: m_Value(V&: Index))))) {
2733 assert(Vec->getType()->getScalarSizeInBits() == PtrSize && "Wrong type");
2734 // Convert the scalar to int followed by insert to eliminate one cast:
2735 // p2i (ins (i2p Vec), Scalar, Index --> ins Vec, (p2i Scalar), Index
2736 Value *NewCast = Builder.CreatePtrToInt(V: Scalar, DestTy: Ty->getScalarType());
2737 return InsertElementInst::Create(Vec, NewElt: NewCast, Idx: Index);
2738 }
2739
2740 return commonCastTransforms(CI);
2741}
2742
2743Instruction *InstCombinerImpl::visitPtrToAddr(PtrToAddrInst &CI) {
2744 Value *SrcOp = CI.getPointerOperand();
2745 Type *Ty = CI.getType();
2746
2747 // (ptrtoaddr (ptrmask P, M))
2748 // -> (and (ptrtoaddr P), M)
2749 // This is generally beneficial as `and` is better supported than `ptrmask`.
2750 Value *Ptr, *Mask;
2751 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(
2752 Ops: m_Value(V&: Ptr), Ops: m_SpecificType(RefTy: Ty, V&: Mask)))))
2753 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToAddr(V: Ptr), V2: Mask);
2754
2755 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2756 return replaceInstUsesWith(I&: CI, V);
2757
2758 // FIXME: Implement variants of ptrtoint folds.
2759 return commonCastTransforms(CI);
2760}
2761
2762/// This input value (which is known to have vector type) is being zero extended
2763/// or truncated to the specified vector type. Since the zext/trunc is done
2764/// using an integer type, we have a (bitcast(cast(bitcast))) pattern,
2765/// endianness will impact which end of the vector that is extended or
2766/// truncated.
2767///
2768/// A vector is always stored with index 0 at the lowest address, which
2769/// corresponds to the most significant bits for a big endian stored integer and
2770/// the least significant bits for little endian. A trunc/zext of an integer
2771/// impacts the big end of the integer. Thus, we need to add/remove elements at
2772/// the front of the vector for big endian targets, and the back of the vector
2773/// for little endian targets.
2774///
2775/// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
2776///
2777/// The source and destination vector types may have different element types.
2778static Instruction *
2779optimizeVectorResizeWithIntegerBitCasts(Value *InVal, VectorType *DestTy,
2780 InstCombinerImpl &IC) {
2781 // We can only do this optimization if the output is a multiple of the input
2782 // element size, or the input is a multiple of the output element size.
2783 // Convert the input type to have the same element type as the output.
2784 VectorType *SrcTy = cast<VectorType>(Val: InVal->getType());
2785
2786 if (SrcTy->getElementType() != DestTy->getElementType()) {
2787 // The input types don't need to be identical, but for now they must be the
2788 // same size. There is no specific reason we couldn't handle things like
2789 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
2790 // there yet.
2791 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
2792 DestTy->getElementType()->getPrimitiveSizeInBits())
2793 return nullptr;
2794
2795 SrcTy =
2796 FixedVectorType::get(ElementType: DestTy->getElementType(),
2797 NumElts: cast<FixedVectorType>(Val: SrcTy)->getNumElements());
2798 InVal = IC.Builder.CreateBitCast(V: InVal, DestTy: SrcTy);
2799 }
2800
2801 bool IsBigEndian = IC.getDataLayout().isBigEndian();
2802 unsigned SrcElts = cast<FixedVectorType>(Val: SrcTy)->getNumElements();
2803 unsigned DestElts = cast<FixedVectorType>(Val: DestTy)->getNumElements();
2804
2805 assert(SrcElts != DestElts && "Element counts should be different.");
2806
2807 // Now that the element types match, get the shuffle mask and RHS of the
2808 // shuffle to use, which depends on whether we're increasing or decreasing the
2809 // size of the input.
2810 auto ShuffleMaskStorage = llvm::to_vector<16>(Range: llvm::seq<int>(Begin: 0, End: SrcElts));
2811 ArrayRef<int> ShuffleMask;
2812 Value *V2;
2813
2814 if (SrcElts > DestElts) {
2815 // If we're shrinking the number of elements (rewriting an integer
2816 // truncate), just shuffle in the elements corresponding to the least
2817 // significant bits from the input and use poison as the second shuffle
2818 // input.
2819 V2 = PoisonValue::get(T: SrcTy);
2820 // Make sure the shuffle mask selects the "least significant bits" by
2821 // keeping elements from back of the src vector for big endian, and from the
2822 // front for little endian.
2823 ShuffleMask = ShuffleMaskStorage;
2824 if (IsBigEndian)
2825 ShuffleMask = ShuffleMask.take_back(N: DestElts);
2826 else
2827 ShuffleMask = ShuffleMask.take_front(N: DestElts);
2828 } else {
2829 // If we're increasing the number of elements (rewriting an integer zext),
2830 // shuffle in all of the elements from InVal. Fill the rest of the result
2831 // elements with zeros from a constant zero.
2832 V2 = Constant::getNullValue(Ty: SrcTy);
2833 // Use first elt from V2 when indicating zero in the shuffle mask.
2834 uint32_t NullElt = SrcElts;
2835 // Extend with null values in the "most significant bits" by adding elements
2836 // in front of the src vector for big endian, and at the back for little
2837 // endian.
2838 unsigned DeltaElts = DestElts - SrcElts;
2839 if (IsBigEndian)
2840 ShuffleMaskStorage.insert(I: ShuffleMaskStorage.begin(), NumToInsert: DeltaElts, Elt: NullElt);
2841 else
2842 ShuffleMaskStorage.append(NumInputs: DeltaElts, Elt: NullElt);
2843 ShuffleMask = ShuffleMaskStorage;
2844 }
2845
2846 return new ShuffleVectorInst(InVal, V2, ShuffleMask);
2847}
2848
2849static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
2850 return Value % Ty->getPrimitiveSizeInBits() == 0;
2851}
2852
2853static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
2854 return Value / Ty->getPrimitiveSizeInBits();
2855}
2856
2857/// V is a value which is inserted into a vector of VecEltTy.
2858/// Look through the value to see if we can decompose it into
2859/// insertions into the vector. See the example in the comment for
2860/// OptimizeIntegerToVectorInsertions for the pattern this handles.
2861/// The type of V is always a non-zero multiple of VecEltTy's size.
2862/// Shift is the number of bits between the lsb of V and the lsb of
2863/// the vector.
2864///
2865/// This returns false if the pattern can't be matched or true if it can,
2866/// filling in Elements with the elements found here.
2867static bool collectInsertionElements(Value *V, unsigned Shift,
2868 SmallVectorImpl<Value *> &Elements,
2869 Type *VecEltTy, bool isBigEndian) {
2870 assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
2871 "Shift should be a multiple of the element type size");
2872
2873 // Poison values never contribute useful bits to the result.
2874 if (match(V, P: m_Poison()))
2875 return true;
2876
2877 // If we got down to a value of the right type, we win, try inserting into the
2878 // right element.
2879 if (V->getType() == VecEltTy) {
2880 // Inserting null doesn't actually insert any elements.
2881 if (Constant *C = dyn_cast<Constant>(Val: V))
2882 if (C->isNullValue())
2883 return true;
2884
2885 unsigned ElementIndex = getTypeSizeIndex(Value: Shift, Ty: VecEltTy);
2886 if (isBigEndian)
2887 ElementIndex = Elements.size() - ElementIndex - 1;
2888
2889 // Fail if multiple elements are inserted into this slot.
2890 if (Elements[ElementIndex])
2891 return false;
2892
2893 Elements[ElementIndex] = V;
2894 return true;
2895 }
2896
2897 if (Constant *C = dyn_cast<Constant>(Val: V)) {
2898 // Figure out the # elements this provides, and bitcast it or slice it up
2899 // as required.
2900 unsigned NumElts = getTypeSizeIndex(Value: C->getType()->getPrimitiveSizeInBits(),
2901 Ty: VecEltTy);
2902 // If the constant is the size of a vector element, we just need to bitcast
2903 // it to the right type so it gets properly inserted.
2904 if (NumElts == 1)
2905 return collectInsertionElements(V: ConstantExpr::getBitCast(C, Ty: VecEltTy),
2906 Shift, Elements, VecEltTy, isBigEndian);
2907
2908 // Okay, this is a constant that covers multiple elements. Slice it up into
2909 // pieces and insert each element-sized piece into the vector.
2910 if (!isa<IntegerType>(Val: C->getType()))
2911 C = ConstantExpr::getBitCast(C, Ty: IntegerType::get(C&: V->getContext(),
2912 NumBits: C->getType()->getPrimitiveSizeInBits()));
2913 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
2914 Type *ElementIntTy = IntegerType::get(C&: C->getContext(), NumBits: ElementSize);
2915
2916 for (unsigned i = 0; i != NumElts; ++i) {
2917 unsigned ShiftI = i * ElementSize;
2918 Constant *Piece = ConstantFoldBinaryInstruction(
2919 Opcode: Instruction::LShr, V1: C, V2: ConstantInt::get(Ty: C->getType(), V: ShiftI));
2920 if (!Piece)
2921 return false;
2922
2923 Piece = ConstantExpr::getTrunc(C: Piece, Ty: ElementIntTy);
2924 if (!collectInsertionElements(V: Piece, Shift: ShiftI + Shift, Elements, VecEltTy,
2925 isBigEndian))
2926 return false;
2927 }
2928 return true;
2929 }
2930
2931 if (!V->hasOneUse()) return false;
2932
2933 Instruction *I = dyn_cast<Instruction>(Val: V);
2934 if (!I) return false;
2935 switch (I->getOpcode()) {
2936 default: return false; // Unhandled case.
2937 case Instruction::BitCast:
2938 if (I->getOperand(i: 0)->getType()->isVectorTy())
2939 return false;
2940 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2941 isBigEndian);
2942 case Instruction::ZExt:
2943 if (!isMultipleOfTypeSize(
2944 Value: I->getOperand(i: 0)->getType()->getPrimitiveSizeInBits(),
2945 Ty: VecEltTy))
2946 return false;
2947 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2948 isBigEndian);
2949 case Instruction::Or:
2950 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2951 isBigEndian) &&
2952 collectInsertionElements(V: I->getOperand(i: 1), Shift, Elements, VecEltTy,
2953 isBigEndian);
2954 case Instruction::Shl: {
2955 // Must be shifting by a constant that is a multiple of the element size.
2956 ConstantInt *CI = dyn_cast<ConstantInt>(Val: I->getOperand(i: 1));
2957 if (!CI) return false;
2958 Shift += CI->getZExtValue();
2959 if (!isMultipleOfTypeSize(Value: Shift, Ty: VecEltTy)) return false;
2960 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2961 isBigEndian);
2962 }
2963
2964 }
2965}
2966
2967
2968/// If the input is an 'or' instruction, we may be doing shifts and ors to
2969/// assemble the elements of the vector manually.
2970/// Try to rip the code out and replace it with insertelements. This is to
2971/// optimize code like this:
2972///
2973/// %tmp37 = bitcast float %inc to i32
2974/// %tmp38 = zext i32 %tmp37 to i64
2975/// %tmp31 = bitcast float %inc5 to i32
2976/// %tmp32 = zext i32 %tmp31 to i64
2977/// %tmp33 = shl i64 %tmp32, 32
2978/// %ins35 = or i64 %tmp33, %tmp38
2979/// %tmp43 = bitcast i64 %ins35 to <2 x float>
2980///
2981/// Into two insertelements that do "buildvector{%inc, %inc5}".
2982static Value *optimizeIntegerToVectorInsertions(BitCastInst &CI,
2983 InstCombinerImpl &IC) {
2984 auto *DestVecTy = cast<FixedVectorType>(Val: CI.getType());
2985 Value *IntInput = CI.getOperand(i_nocapture: 0);
2986
2987 // if the int input is just an undef value do not try to optimize to vector
2988 // insertions as it will prevent undef propagation
2989 if (isa<UndefValue>(Val: IntInput))
2990 return nullptr;
2991
2992 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
2993 if (!collectInsertionElements(V: IntInput, Shift: 0, Elements,
2994 VecEltTy: DestVecTy->getElementType(),
2995 isBigEndian: IC.getDataLayout().isBigEndian()))
2996 return nullptr;
2997
2998 // If we succeeded, we know that all of the element are specified by Elements
2999 // or are zero if Elements has a null entry. Recast this as a set of
3000 // insertions.
3001 Value *Result = Constant::getNullValue(Ty: CI.getType());
3002 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
3003 if (!Elements[i]) continue; // Unset element.
3004
3005 Result = IC.Builder.CreateInsertElement(Vec: Result, NewElt: Elements[i], Idx: i);
3006 }
3007
3008 return Result;
3009}
3010
3011/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
3012/// vector followed by extract element. The backend tends to handle bitcasts of
3013/// vectors better than bitcasts of scalars because vector registers are
3014/// usually not type-specific like scalar integer or scalar floating-point.
3015static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast,
3016 InstCombinerImpl &IC) {
3017 Value *VecOp, *Index;
3018 if (!match(V: BitCast.getOperand(i_nocapture: 0),
3019 P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_Value(V&: Index)))))
3020 return nullptr;
3021
3022 // The bitcast must be to a vectorizable type, otherwise we can't make a new
3023 // type to extract from.
3024 Type *DestType = BitCast.getType();
3025 VectorType *VecType = cast<VectorType>(Val: VecOp->getType());
3026 if (VectorType::isValidElementType(ElemTy: DestType)) {
3027 auto *NewVecType = VectorType::get(ElementType: DestType, Other: VecType);
3028 auto *NewBC = IC.Builder.CreateBitCast(V: VecOp, DestTy: NewVecType, Name: "bc");
3029 return ExtractElementInst::Create(Vec: NewBC, Idx: Index);
3030 }
3031
3032 // Only solve DestType is vector to avoid inverse transform in visitBitCast.
3033 // bitcast (extractelement <1 x elt>, dest) -> bitcast(<1 x elt>, dest)
3034 auto *FixedVType = dyn_cast<FixedVectorType>(Val: VecType);
3035 if (DestType->isVectorTy() && FixedVType && FixedVType->getNumElements() == 1)
3036 return CastInst::Create(Instruction::BitCast, S: VecOp, Ty: DestType);
3037
3038 return nullptr;
3039}
3040
3041/// Change the type of a bitwise logic operation if we can eliminate a bitcast.
3042static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast,
3043 InstCombiner::BuilderTy &Builder) {
3044 Type *DestTy = BitCast.getType();
3045 BinaryOperator *BO;
3046
3047 if (!match(V: BitCast.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BO))) ||
3048 !BO->isBitwiseLogicOp())
3049 return nullptr;
3050
3051 // FIXME: This transform is restricted to vector types to avoid backend
3052 // problems caused by creating potentially illegal operations. If a fix-up is
3053 // added to handle that situation, we can remove this check.
3054 if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
3055 return nullptr;
3056
3057 if (DestTy->isFPOrFPVectorTy()) {
3058 Value *X, *Y;
3059 // bitcast(logic(bitcast(X), bitcast(Y))) -> bitcast'(logic(bitcast'(X), Y))
3060 if (match(V: BO->getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
3061 match(V: BO->getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: Y))))) {
3062 if (X->getType()->isFPOrFPVectorTy() &&
3063 Y->getType()->isIntOrIntVectorTy()) {
3064 Value *CastedOp =
3065 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy: Y->getType());
3066 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: Y);
3067 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
3068 }
3069 if (X->getType()->isIntOrIntVectorTy() &&
3070 Y->getType()->isFPOrFPVectorTy()) {
3071 Value *CastedOp =
3072 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy: X->getType());
3073 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: X);
3074 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
3075 }
3076 }
3077 return nullptr;
3078 }
3079
3080 if (!DestTy->isIntOrIntVectorTy())
3081 return nullptr;
3082
3083 Value *X;
3084 if (match(V: BO->getOperand(i_nocapture: 0),
3085 P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3086 !isa<Constant>(Val: X)) {
3087 // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
3088 Value *CastedOp1 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy);
3089 return BinaryOperator::Create(Op: BO->getOpcode(), S1: X, S2: CastedOp1);
3090 }
3091
3092 if (match(V: BO->getOperand(i_nocapture: 1),
3093 P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3094 !isa<Constant>(Val: X)) {
3095 // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
3096 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
3097 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: X);
3098 }
3099
3100 // Canonicalize vector bitcasts to come before vector bitwise logic with a
3101 // constant. This eases recognition of special constants for later ops.
3102 // Example:
3103 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
3104 Constant *C;
3105 if (match(V: BO->getOperand(i_nocapture: 1), P: m_Constant(C))) {
3106 // bitcast (logic X, C) --> logic (bitcast X, C')
3107 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
3108 Value *CastedC = Builder.CreateBitCast(V: C, DestTy);
3109 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: CastedC);
3110 }
3111
3112 return nullptr;
3113}
3114
3115/// Change the type of a select if we can eliminate a bitcast.
3116static Instruction *foldBitCastSelect(BitCastInst &BitCast,
3117 InstCombiner::BuilderTy &Builder) {
3118 Value *Cond, *TVal, *FVal;
3119 if (!match(V: BitCast.getOperand(i_nocapture: 0),
3120 P: m_OneUse(SubPattern: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: TVal), R: m_Value(V&: FVal)))))
3121 return nullptr;
3122
3123 // A vector select must maintain the same number of elements in its operands.
3124 Type *CondTy = Cond->getType();
3125 Type *DestTy = BitCast.getType();
3126
3127 auto *DestVecTy = dyn_cast<VectorType>(Val: DestTy);
3128
3129 if (auto *CondVTy = dyn_cast<VectorType>(Val: CondTy))
3130 if (!DestVecTy ||
3131 CondVTy->getElementCount() != DestVecTy->getElementCount())
3132 return nullptr;
3133
3134 auto *Sel = cast<Instruction>(Val: BitCast.getOperand(i_nocapture: 0));
3135 auto *SrcVecTy = dyn_cast<VectorType>(Val: TVal->getType());
3136
3137 if ((isa<Constant>(Val: TVal) || isa<Constant>(Val: FVal)) &&
3138 (!DestVecTy ||
3139 (SrcVecTy && ElementCount::isKnownLE(LHS: DestVecTy->getElementCount(),
3140 RHS: SrcVecTy->getElementCount())))) {
3141 // Avoid introducing select of vector (or select of vector with more
3142 // elements) until the backend can undo this transformation.
3143 Value *CastedTVal = Builder.CreateBitCast(V: TVal, DestTy);
3144 Value *CastedFVal = Builder.CreateBitCast(V: FVal, DestTy);
3145 return SelectInst::Create(C: Cond, S1: CastedTVal, S2: CastedFVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3146 }
3147
3148 // FIXME: This transform is restricted from changing the select between
3149 // scalars and vectors to avoid backend problems caused by creating
3150 // potentially illegal operations. If a fix-up is added to handle that
3151 // situation, we can remove this check.
3152 if ((DestVecTy != nullptr) != (SrcVecTy != nullptr))
3153 return nullptr;
3154
3155 Value *X;
3156 if (match(V: TVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3157 !isa<Constant>(Val: X)) {
3158 // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
3159 Value *CastedVal = Builder.CreateBitCast(V: FVal, DestTy);
3160 return SelectInst::Create(C: Cond, S1: X, S2: CastedVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3161 }
3162
3163 if (match(V: FVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3164 !isa<Constant>(Val: X)) {
3165 // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
3166 Value *CastedVal = Builder.CreateBitCast(V: TVal, DestTy);
3167 return SelectInst::Create(C: Cond, S1: CastedVal, S2: X, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3168 }
3169
3170 return nullptr;
3171}
3172
3173/// Check if all users of CI are StoreInsts.
3174static bool hasStoreUsersOnly(CastInst &CI) {
3175 for (User *U : CI.users()) {
3176 if (!isa<StoreInst>(Val: U))
3177 return false;
3178 }
3179 return true;
3180}
3181
3182/// This function handles following case
3183///
3184/// A -> B cast
3185/// PHI
3186/// B -> A cast
3187///
3188/// All the related PHI nodes can be replaced by new PHI nodes with type A.
3189/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
3190Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
3191 PHINode *PN) {
3192 // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
3193 if (hasStoreUsersOnly(CI))
3194 return nullptr;
3195
3196 Value *Src = CI.getOperand(i_nocapture: 0);
3197 Type *SrcTy = Src->getType(); // Type B
3198 Type *DestTy = CI.getType(); // Type A
3199
3200 SmallVector<PHINode *, 4> PhiWorklist;
3201 SmallSetVector<PHINode *, 4> OldPhiNodes;
3202
3203 // Find all of the A->B casts and PHI nodes.
3204 // We need to inspect all related PHI nodes, but PHIs can be cyclic, so
3205 // OldPhiNodes is used to track all known PHI nodes, before adding a new
3206 // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
3207 PhiWorklist.push_back(Elt: PN);
3208 OldPhiNodes.insert(X: PN);
3209 while (!PhiWorklist.empty()) {
3210 auto *OldPN = PhiWorklist.pop_back_val();
3211 for (Value *IncValue : OldPN->incoming_values()) {
3212 if (isa<Constant>(Val: IncValue))
3213 continue;
3214
3215 if (auto *LI = dyn_cast<LoadInst>(Val: IncValue)) {
3216 // If there is a sequence of one or more load instructions, each loaded
3217 // value is used as address of later load instruction, bitcast is
3218 // necessary to change the value type, don't optimize it. For
3219 // simplicity we give up if the load address comes from another load.
3220 Value *Addr = LI->getOperand(i_nocapture: 0);
3221 if (Addr == &CI || isa<LoadInst>(Val: Addr))
3222 return nullptr;
3223 // Don't tranform "load <256 x i32>, <256 x i32>*" to
3224 // "load x86_amx, x86_amx*", because x86_amx* is invalid.
3225 // TODO: Remove this check when bitcast between vector and x86_amx
3226 // is replaced with a specific intrinsic.
3227 if (DestTy->isX86_AMXTy())
3228 return nullptr;
3229 if (LI->hasOneUse() && LI->isSimple())
3230 continue;
3231 // If a LoadInst has more than one use, changing the type of loaded
3232 // value may create another bitcast.
3233 return nullptr;
3234 }
3235
3236 if (auto *PNode = dyn_cast<PHINode>(Val: IncValue)) {
3237 if (OldPhiNodes.insert(X: PNode))
3238 PhiWorklist.push_back(Elt: PNode);
3239 continue;
3240 }
3241
3242 auto *BCI = dyn_cast<BitCastInst>(Val: IncValue);
3243 // We can't handle other instructions.
3244 if (!BCI)
3245 return nullptr;
3246
3247 // Verify it's a A->B cast.
3248 Type *TyA = BCI->getOperand(i_nocapture: 0)->getType();
3249 Type *TyB = BCI->getType();
3250 if (TyA != DestTy || TyB != SrcTy)
3251 return nullptr;
3252 }
3253 }
3254
3255 // Check that each user of each old PHI node is something that we can
3256 // rewrite, so that all of the old PHI nodes can be cleaned up afterwards.
3257 for (auto *OldPN : OldPhiNodes) {
3258 for (User *V : OldPN->users()) {
3259 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3260 if (!SI->isSimple() || SI->getOperand(i_nocapture: 0) != OldPN)
3261 return nullptr;
3262 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3263 // Verify it's a B->A cast.
3264 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3265 Type *TyA = BCI->getType();
3266 if (TyA != DestTy || TyB != SrcTy)
3267 return nullptr;
3268 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3269 // As long as the user is another old PHI node, then even if we don't
3270 // rewrite it, the PHI web we're considering won't have any users
3271 // outside itself, so it'll be dead.
3272 if (!OldPhiNodes.contains(key: PHI))
3273 return nullptr;
3274 } else {
3275 return nullptr;
3276 }
3277 }
3278 }
3279
3280 // For each old PHI node, create a corresponding new PHI node with a type A.
3281 SmallDenseMap<PHINode *, PHINode *> NewPNodes;
3282 for (auto *OldPN : OldPhiNodes) {
3283 Builder.SetInsertPoint(OldPN);
3284 PHINode *NewPN = Builder.CreatePHI(Ty: DestTy, NumReservedValues: OldPN->getNumOperands());
3285 NewPNodes[OldPN] = NewPN;
3286 }
3287
3288 // Fill in the operands of new PHI nodes.
3289 for (auto *OldPN : OldPhiNodes) {
3290 PHINode *NewPN = NewPNodes[OldPN];
3291 for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
3292 Value *V = OldPN->getOperand(i_nocapture: j);
3293 Value *NewV = nullptr;
3294 if (auto *C = dyn_cast<Constant>(Val: V)) {
3295 NewV = ConstantExpr::getBitCast(C, Ty: DestTy);
3296 } else if (auto *LI = dyn_cast<LoadInst>(Val: V)) {
3297 // Explicitly perform load combine to make sure no opposing transform
3298 // can remove the bitcast in the meantime and trigger an infinite loop.
3299 Builder.SetInsertPoint(LI);
3300 NewV = combineLoadToNewType(LI&: *LI, NewTy: DestTy);
3301 // Remove the old load and its use in the old phi, which itself becomes
3302 // dead once the whole transform finishes.
3303 replaceInstUsesWith(I&: *LI, V: PoisonValue::get(T: LI->getType()));
3304 eraseInstFromFunction(I&: *LI);
3305 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3306 NewV = BCI->getOperand(i_nocapture: 0);
3307 } else if (auto *PrevPN = dyn_cast<PHINode>(Val: V)) {
3308 NewV = NewPNodes[PrevPN];
3309 }
3310 assert(NewV);
3311 NewPN->addIncoming(V: NewV, BB: OldPN->getIncomingBlock(i: j));
3312 }
3313 }
3314
3315 // Traverse all accumulated PHI nodes and process its users,
3316 // which are Stores and BitcCasts. Without this processing
3317 // NewPHI nodes could be replicated and could lead to extra
3318 // moves generated after DeSSA.
3319 // If there is a store with type B, change it to type A.
3320
3321
3322 // Replace users of BitCast B->A with NewPHI. These will help
3323 // later to get rid off a closure formed by OldPHI nodes.
3324 Instruction *RetVal = nullptr;
3325 for (auto *OldPN : OldPhiNodes) {
3326 PHINode *NewPN = NewPNodes[OldPN];
3327 for (User *V : make_early_inc_range(Range: OldPN->users())) {
3328 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3329 assert(SI->isSimple() && SI->getOperand(0) == OldPN);
3330 Builder.SetInsertPoint(SI);
3331 auto *NewBC =
3332 cast<BitCastInst>(Val: Builder.CreateBitCast(V: NewPN, DestTy: SrcTy));
3333 SI->setOperand(i_nocapture: 0, Val_nocapture: NewBC);
3334 Worklist.push(I: SI);
3335 assert(hasStoreUsersOnly(*NewBC));
3336 }
3337 else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3338 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3339 Type *TyA = BCI->getType();
3340 assert(TyA == DestTy && TyB == SrcTy);
3341 (void) TyA;
3342 (void) TyB;
3343 Instruction *I = replaceInstUsesWith(I&: *BCI, V: NewPN);
3344 if (BCI == &CI)
3345 RetVal = I;
3346 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3347 assert(OldPhiNodes.contains(PHI));
3348 (void) PHI;
3349 } else {
3350 llvm_unreachable("all uses should be handled");
3351 }
3352 }
3353 }
3354
3355 return RetVal;
3356}
3357
3358/// Fold (bitcast (or (and (bitcast X to int), signmask), nneg Y) to fp) to
3359/// copysign((bitcast Y to fp), X)
3360static Value *foldCopySignIdioms(BitCastInst &CI,
3361 InstCombiner::BuilderTy &Builder,
3362 const SimplifyQuery &SQ) {
3363 Value *X, *Y;
3364 Type *FTy = CI.getType();
3365 if (!FTy->isFPOrFPVectorTy())
3366 return nullptr;
3367 if (!match(V: &CI, P: m_ElementWiseBitCast(Op: m_c_Or(
3368 L: m_And(L: m_ElementWiseBitCast(Op: m_Value(V&: X)), R: m_SignMask()),
3369 R: m_Value(V&: Y)))))
3370 return nullptr;
3371 if (X->getType() != FTy)
3372 return nullptr;
3373 if (!isKnownNonNegative(V: Y, SQ))
3374 return nullptr;
3375
3376 return Builder.CreateCopySign(LHS: Builder.CreateBitCast(V: Y, DestTy: FTy), RHS: X);
3377}
3378
3379Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
3380 // If the operands are integer typed then apply the integer transforms,
3381 // otherwise just apply the common ones.
3382 Value *Src = CI.getOperand(i_nocapture: 0);
3383 Type *SrcTy = Src->getType();
3384 Type *DestTy = CI.getType();
3385
3386 // Get rid of casts from one type to the same type. These are useless and can
3387 // be replaced by the operand.
3388 if (DestTy == Src->getType())
3389 return replaceInstUsesWith(I&: CI, V: Src);
3390
3391 if (isa<FixedVectorType>(Val: DestTy)) {
3392 if (isa<IntegerType>(Val: SrcTy)) {
3393 // If this is a cast from an integer to vector, check to see if the input
3394 // is a trunc or zext of a bitcast from vector. If so, we can replace all
3395 // the casts with a shuffle and (potentially) a bitcast.
3396 if (isa<TruncInst>(Val: Src) || isa<ZExtInst>(Val: Src)) {
3397 CastInst *SrcCast = cast<CastInst>(Val: Src);
3398 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(Val: SrcCast->getOperand(i_nocapture: 0)))
3399 if (isa<VectorType>(Val: BCIn->getOperand(i_nocapture: 0)->getType()))
3400 if (Instruction *I = optimizeVectorResizeWithIntegerBitCasts(
3401 InVal: BCIn->getOperand(i_nocapture: 0), DestTy: cast<VectorType>(Val: DestTy), IC&: *this))
3402 return I;
3403 }
3404
3405 // If the input is an 'or' instruction, we may be doing shifts and ors to
3406 // assemble the elements of the vector manually. Try to rip the code out
3407 // and replace it with insertelements.
3408 if (Value *V = optimizeIntegerToVectorInsertions(CI, IC&: *this))
3409 return replaceInstUsesWith(I&: CI, V);
3410 }
3411 }
3412
3413 if (FixedVectorType *SrcVTy = dyn_cast<FixedVectorType>(Val: SrcTy)) {
3414 if (SrcVTy->getNumElements() == 1) {
3415 // If our destination is not a vector, then make this a straight
3416 // scalar-scalar cast.
3417 if (!DestTy->isVectorTy()) {
3418 Value *Elem = Builder.CreateExtractElement(Vec: Src, Idx: uint64_t{0});
3419 return CastInst::Create(Instruction::BitCast, S: Elem, Ty: DestTy);
3420 }
3421
3422 // Otherwise, see if our source is an insert. If so, then use the scalar
3423 // component directly:
3424 // bitcast (inselt <1 x elt> V, X, 0) to <n x m> --> bitcast X to <n x m>
3425 if (auto *InsElt = dyn_cast<InsertElementInst>(Val: Src))
3426 return new BitCastInst(InsElt->getOperand(i_nocapture: 1), DestTy);
3427 }
3428
3429 // Convert an artificial vector insert into more analyzable bitwise logic.
3430 unsigned BitWidth = DestTy->getScalarSizeInBits();
3431 Value *X, *Y;
3432 uint64_t IndexC;
3433 if (match(V: Src, P: m_OneUse(SubPattern: m_InsertElt(
3434 Val: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X))),
3435 Elt: m_Value(V&: Y), Idx: m_ConstantInt(V&: IndexC)))) &&
3436 DestTy->isIntegerTy() && Y->getType()->isIntegerTy() &&
3437 isDesirableIntType(BitWidth)) {
3438 // Adjust for big endian - the LSBs are at the high index.
3439 if (DL.isBigEndian())
3440 IndexC = SrcVTy->getNumElements() - 1 - IndexC;
3441
3442 // We only handle (endian-normalized) insert to index 0. Any other insert
3443 // would require a left-shift, so that is an extra instruction.
3444 if (IndexC == 0) {
3445 // bitcast (inselt (bitcast X), Y, 0) --> or (and X, MaskC), (zext Y)
3446 unsigned EltWidth = Y->getType()->getScalarSizeInBits();
3447 APInt MaskC = APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - EltWidth);
3448 Value *AndX = Builder.CreateAnd(LHS: X, RHS: MaskC);
3449 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
3450 return BinaryOperator::CreateOr(V1: AndX, V2: ZextY);
3451 }
3452 }
3453 }
3454
3455 if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Val: Src)) {
3456 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
3457 // a bitcast to a vector with the same # elts.
3458 Value *ShufOp0 = Shuf->getOperand(i_nocapture: 0);
3459 Value *ShufOp1 = Shuf->getOperand(i_nocapture: 1);
3460 auto ShufElts = cast<VectorType>(Val: Shuf->getType())->getElementCount();
3461 auto SrcVecElts = cast<VectorType>(Val: ShufOp0->getType())->getElementCount();
3462 if (Shuf->hasOneUse() && DestTy->isVectorTy() &&
3463 cast<VectorType>(Val: DestTy)->getElementCount() == ShufElts &&
3464 ShufElts == SrcVecElts) {
3465 BitCastInst *Tmp;
3466 // If either of the operands is a cast from CI.getType(), then
3467 // evaluating the shuffle in the casted destination's type will allow
3468 // us to eliminate at least one cast.
3469 if (((Tmp = dyn_cast<BitCastInst>(Val: ShufOp0)) &&
3470 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy) ||
3471 ((Tmp = dyn_cast<BitCastInst>(Val: ShufOp1)) &&
3472 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy)) {
3473 Value *LHS = Builder.CreateBitCast(V: ShufOp0, DestTy);
3474 Value *RHS = Builder.CreateBitCast(V: ShufOp1, DestTy);
3475 // Return a new shuffle vector. Use the same element ID's, as we
3476 // know the vector types match #elts.
3477 return new ShuffleVectorInst(LHS, RHS, Shuf->getShuffleMask());
3478 }
3479 }
3480
3481 // A bitcasted-to-scalar and byte/bit reversing shuffle is better recognized
3482 // as a byte/bit swap:
3483 // bitcast <N x i8> (shuf X, undef, <N, N-1,...0>) -> bswap (bitcast X)
3484 // bitcast <N x i1> (shuf X, undef, <N, N-1,...0>) -> bitreverse (bitcast X)
3485 if (DestTy->isIntegerTy() && ShufElts.getKnownMinValue() % 2 == 0 &&
3486 Shuf->hasOneUse() && Shuf->isReverse() && match(V: ShufOp1, P: m_Poison())) {
3487 unsigned IntrinsicNum = 0;
3488 if (DL.isLegalInteger(Width: DestTy->getScalarSizeInBits()) &&
3489 SrcTy->getScalarSizeInBits() == 8) {
3490 IntrinsicNum = Intrinsic::bswap;
3491 } else if (SrcTy->getScalarSizeInBits() == 1) {
3492 IntrinsicNum = Intrinsic::bitreverse;
3493 }
3494 if (IntrinsicNum != 0) {
3495 assert(ShufOp0->getType() == SrcTy && "Unexpected shuffle mask");
3496 Function *BswapOrBitreverse = Intrinsic::getOrInsertDeclaration(
3497 M: CI.getModule(), id: IntrinsicNum, OverloadTys: DestTy);
3498 Value *ScalarX = Builder.CreateBitCast(V: ShufOp0, DestTy);
3499 return CallInst::Create(Func: BswapOrBitreverse, Args: {ScalarX});
3500 }
3501 }
3502 }
3503
3504 // Handle the A->B->A cast, and there is an intervening PHI node.
3505 if (PHINode *PN = dyn_cast<PHINode>(Val: Src))
3506 if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
3507 return I;
3508
3509 if (Instruction *I = canonicalizeBitCastExtElt(BitCast&: CI, IC&: *this))
3510 return I;
3511
3512 if (Instruction *I = foldBitCastBitwiseLogic(BitCast&: CI, Builder))
3513 return I;
3514
3515 if (Instruction *I = foldBitCastSelect(BitCast&: CI, Builder))
3516 return I;
3517
3518 if (Value *V = foldCopySignIdioms(CI, Builder, SQ: SQ.getWithInstruction(I: &CI)))
3519 return replaceInstUsesWith(I&: CI, V);
3520
3521 return commonCastTransforms(CI);
3522}
3523
3524Instruction *InstCombinerImpl::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
3525 return commonCastTransforms(CI);
3526}
3527