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_Value(V&: X))) || match(V, P: m_Trunc(Op: m_Value(V&: X)))) &&
482 X->getType() == Ty)
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>(Op0: m_Value(V&: AbsOp), Op1: 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_Value(V&: X))) && X->getType() == DestTy) {
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_Value(V&: X))) && X->getType() == DestTy) {
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
1092 // See if we can simplify any instructions used by the input whose sole
1093 // purpose is to compute bits we don't care about.
1094 if (SimplifyDemandedInstructionBits(Inst&: Trunc))
1095 return &Trunc;
1096
1097 if (DestWidth == 1) {
1098 Value *Zero = Constant::getNullValue(Ty: SrcTy);
1099
1100 Value *X;
1101 const APInt *C1;
1102 Constant *C2;
1103 if (match(V: Src, P: m_OneUse(SubPattern: m_Shr(L: m_Shl(L: m_Power2(V&: C1), R: m_Value(V&: X)),
1104 R: m_ImmConstant(C&: C2))))) {
1105 // trunc ((C1 << X) >> C2) to i1 --> X == (C2-cttz(C1)), where C1 is pow2
1106 Constant *Log2C1 = ConstantInt::get(Ty: SrcTy, V: C1->exactLogBase2());
1107 Constant *CmpC = ConstantExpr::getSub(C1: C2, C2: Log2C1);
1108 return new ICmpInst(ICmpInst::ICMP_EQ, X, CmpC);
1109 }
1110
1111 if (match(V: Src, P: m_Shr(L: m_Value(V&: X), R: m_SpecificInt(V: SrcWidth - 1)))) {
1112 // trunc (ashr X, BW-1) to i1 --> icmp slt X, 0
1113 // trunc (lshr X, BW-1) to i1 --> icmp slt X, 0
1114 return new ICmpInst(ICmpInst::ICMP_SLT, X, Zero);
1115 }
1116
1117 Constant *C;
1118 if (match(V: Src, P: m_OneUse(SubPattern: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C))))) {
1119 // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
1120 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1121 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1122 Value *And = Builder.CreateAnd(LHS: X, RHS: MaskC);
1123 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1124 }
1125 if (match(V: Src, P: m_OneUse(SubPattern: m_c_Or(L: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C)),
1126 R: m_Deferred(V: X))))) {
1127 // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
1128 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1129 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1130 Value *And = Builder.CreateAnd(LHS: X, RHS: Builder.CreateOr(LHS: MaskC, RHS: One));
1131 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1132 }
1133
1134 {
1135 const APInt *C;
1136 if (match(V: Src, P: m_Shl(L: m_APInt(Res&: C), R: m_Value(V&: X))) && (*C)[0] == 1) {
1137 // trunc (C << X) to i1 --> X == 0, where C is odd
1138 return new ICmpInst(ICmpInst::Predicate::ICMP_EQ, X, Zero);
1139 }
1140 }
1141
1142 if (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) {
1143 Value *X, *Y;
1144 if (match(V: Src, P: m_Xor(L: m_Value(V&: X), R: m_Value(V&: Y))))
1145 return new ICmpInst(ICmpInst::ICMP_NE, X, Y);
1146 }
1147
1148 if (match(V: Src,
1149 P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::usub_sat>(Op0: m_One(), Op1: m_Value(V&: X)))))
1150 return new ICmpInst(ICmpInst::ICMP_EQ, X,
1151 ConstantInt::getNullValue(Ty: SrcTy));
1152 }
1153
1154 Value *A, *B;
1155 Constant *C;
1156
1157 // trunc(u/smin(zext(a) + zext(b), MAX)) --> uadd.sat(a, b)
1158 if (match(V: Src,
1159 P: m_OneUse(SubPattern: m_CombineOr(
1160 Ps: m_UMin(Op0: m_OneUse(SubPattern: m_Add(L: m_ZExt(Op: m_Value(V&: A)), R: m_ZExt(Op: m_Value(V&: B)))),
1161 Op1: m_SpecificInt(V: APInt::getMaxValue(numBits: DestWidth))),
1162 Ps: m_SMin(Op0: m_OneUse(SubPattern: m_Add(L: m_ZExt(Op: m_Value(V&: A)), R: m_ZExt(Op: m_Value(V&: B)))),
1163 Op1: m_SpecificInt(V: APInt::getMaxValue(numBits: DestWidth)))))) &&
1164 A->getType() == DestTy && B->getType() == DestTy) {
1165 return replaceInstUsesWith(
1166 I&: Trunc, V: Builder.CreateBinaryIntrinsic(ID: Intrinsic::uadd_sat, LHS: A, RHS: B));
1167 }
1168
1169 // trunc(smax(zext(a) - zext(b), 0)) --> usub.sat(a, b)
1170 if (match(V: Src, P: m_OneUse(SubPattern: m_SMax(
1171 Op0: m_OneUse(SubPattern: m_Sub(L: m_ZExt(Op: m_Value(V&: A)), R: m_ZExt(Op: m_Value(V&: B)))),
1172 Op1: m_Zero()))) &&
1173 A->getType() == DestTy && B->getType() == DestTy) {
1174 return replaceInstUsesWith(
1175 I&: Trunc, V: Builder.CreateBinaryIntrinsic(ID: Intrinsic::usub_sat, LHS: A, RHS: B));
1176 }
1177
1178 if (match(V: Src, P: m_LShr(L: m_SExt(Op: m_Value(V&: A)), R: m_Constant(C)))) {
1179 unsigned AWidth = A->getType()->getScalarSizeInBits();
1180 unsigned MaxShiftAmt = SrcWidth - std::max(a: DestWidth, b: AWidth);
1181 auto *OldSh = cast<Instruction>(Val: Src);
1182 bool IsExact = OldSh->isExact();
1183
1184 // If the shift is small enough, all zero bits created by the shift are
1185 // removed by the trunc.
1186 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
1187 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
1188 auto GetNewShAmt = [&](unsigned Width) {
1189 Constant *MaxAmt = ConstantInt::get(Ty: SrcTy, V: Width - 1, IsSigned: false);
1190 Constant *Cmp =
1191 ConstantFoldCompareInstOperands(Predicate: ICmpInst::ICMP_ULT, LHS: C, RHS: MaxAmt, DL);
1192 Constant *ShAmt = ConstantFoldSelectInstruction(Cond: Cmp, V1: C, V2: MaxAmt);
1193 return ConstantFoldCastOperand(Opcode: Instruction::Trunc, C: ShAmt, DestTy: A->getType(),
1194 DL);
1195 };
1196
1197 // trunc (lshr (sext A), C) --> ashr A, C
1198 if (A->getType() == DestTy) {
1199 Constant *ShAmt = GetNewShAmt(DestWidth);
1200 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
1201 return IsExact ? BinaryOperator::CreateExactAShr(V1: A, V2: ShAmt)
1202 : BinaryOperator::CreateAShr(V1: A, V2: ShAmt);
1203 }
1204 // The types are mismatched, so create a cast after shifting:
1205 // trunc (lshr (sext A), C) --> sext/trunc (ashr A, C)
1206 if (Src->hasOneUse()) {
1207 Constant *ShAmt = GetNewShAmt(AWidth);
1208 Value *Shift = Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: "", isExact: IsExact);
1209 return CastInst::CreateIntegerCast(S: Shift, Ty: DestTy, isSigned: true);
1210 }
1211 }
1212 // TODO: Mask high bits with 'and'.
1213 }
1214
1215 if (Instruction *I = narrowBinOp(Trunc))
1216 return I;
1217
1218 if (Instruction *I = shrinkSplatShuffle(Trunc, Builder))
1219 return I;
1220
1221 if (Instruction *I = shrinkInsertElt(Trunc, Builder))
1222 return I;
1223
1224 if (Src->hasOneUse() &&
1225 (isa<VectorType>(Val: SrcTy) || shouldChangeType(From: SrcTy, To: DestTy))) {
1226 // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
1227 // dest type is native and cst < dest size.
1228 if (match(V: Src, P: m_Shl(L: m_Value(V&: A), R: m_Constant(C))) &&
1229 !match(V: A, P: m_Shr(L: m_Value(), R: m_Constant()))) {
1230 // Skip shifts of shift by constants. It undoes a combine in
1231 // FoldShiftByConstant and is the extend in reg pattern.
1232 APInt Threshold = APInt(C->getType()->getScalarSizeInBits(), DestWidth);
1233 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULT, Threshold))) {
1234 Value *NewTrunc = Builder.CreateTrunc(V: A, DestTy, Name: A->getName() + ".tr");
1235 return BinaryOperator::Create(Op: Instruction::Shl, S1: NewTrunc,
1236 S2: ConstantExpr::getTrunc(C, Ty: DestTy));
1237 }
1238 }
1239 }
1240
1241 // trunc (select(icmp_ult(A, DestTy_umax+1), A, sext(icmp_sgt(A, 0)))) -->
1242 // trunc (smin(smax(0, A), DestTy_umax))
1243 if (SrcTy->isIntegerTy() && isPowerOf2_64(Value: SrcTy->getPrimitiveSizeInBits()) &&
1244 isPowerOf2_64(Value: DestTy->getPrimitiveSizeInBits()) &&
1245 match(V: Src, P: m_OneUse(SubPattern: m_Select(
1246 C: m_OneUse(SubPattern: m_SpecificICmp(MatchPred: ICmpInst::ICMP_ULT, L: m_Value(V&: A),
1247 R: m_Constant(C))),
1248 L: m_Deferred(V: A),
1249 R: m_OneUse(SubPattern: m_SExt(Op: m_OneUse(SubPattern: m_SpecificICmp(
1250 MatchPred: ICmpInst::ICMP_SGT, L: m_Deferred(V: A), R: m_Zero())))))))) {
1251 APInt UpperBound = C->getUniqueInteger();
1252 APInt TruncatedMax = APInt::getAllOnes(numBits: DestTy->getIntegerBitWidth());
1253 TruncatedMax = TruncatedMax.zext(width: UpperBound.getBitWidth());
1254 if (!UpperBound.isZero() && UpperBound - 1 == TruncatedMax) {
1255 Value *SMax = Builder.CreateIntrinsic(ID: Intrinsic::smax, OverloadTypes: {SrcTy},
1256 Args: {ConstantInt::get(Ty: SrcTy, V: 0), A});
1257 Value *SMin = Builder.CreateIntrinsic(
1258 ID: Intrinsic::smin, OverloadTypes: {SrcTy},
1259 Args: {SMax, ConstantInt::get(Ty: SrcTy, V: TruncatedMax)});
1260 return new TruncInst(SMin, DestTy);
1261 }
1262 }
1263
1264 if (Instruction *I = foldVecTruncToExtElt(Trunc, IC&: *this))
1265 return I;
1266
1267 if (Instruction *I = foldVecExtTruncToExtElt(Trunc, IC&: *this))
1268 return I;
1269
1270 // trunc (ctlz_i32(zext(A), B) --> add(ctlz_i16(A, B), C)
1271 if (match(V: Src, P: m_OneUse(SubPattern: m_Ctlz(Op0: m_ZExt(Op: m_Value(V&: A)), Op1: m_Value(V&: B))))) {
1272 unsigned AWidth = A->getType()->getScalarSizeInBits();
1273 if (AWidth == DestWidth && AWidth > Log2_32(Value: SrcWidth)) {
1274 Value *WidthDiff = ConstantInt::get(Ty: A->getType(), V: SrcWidth - AWidth);
1275 Value *NarrowCtlz =
1276 Builder.CreateIntrinsic(ID: Intrinsic::ctlz, OverloadTypes: {Trunc.getType()}, Args: {A, B});
1277 return BinaryOperator::CreateAdd(V1: NarrowCtlz, V2: WidthDiff);
1278 }
1279 }
1280
1281 if (match(V: Src, P: m_VScale())) {
1282 if (Trunc.getFunction() &&
1283 Trunc.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1284 Attribute Attr =
1285 Trunc.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1286 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
1287 if (Log2_32(Value: *MaxVScale) < DestWidth)
1288 return replaceInstUsesWith(I&: Trunc, V: Builder.CreateVScale(Ty: DestTy));
1289 }
1290 }
1291
1292 // trunc(scmp(x, y)) -> scmp(x, y) with a narrower result type.
1293 // trunc(ucmp(x, y)) -> ucmp(x, y) with a narrower result type.
1294 // scmp/ucmp produce only -1, 0, or 1, so any result type with at least 2
1295 // bits can represent every possible value and the truncation is lossless.
1296 if (DestWidth >= 2)
1297 if (auto *CI = dyn_cast<CmpIntrinsic>(Val: Src); CI && CI->hasOneUse())
1298 return replaceInstUsesWith(
1299 I&: Trunc, V: Builder.CreateIntrinsic(RetTy: DestTy, ID: CI->getIntrinsicID(),
1300 Args: {CI->getLHS(), CI->getRHS()}));
1301
1302 if (DestWidth == 1 &&
1303 (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) &&
1304 isKnownNonZero(V: Src, Q: SQ.getWithInstruction(I: &Trunc)))
1305 return replaceInstUsesWith(I&: Trunc, V: ConstantInt::getTrue(Ty: DestTy));
1306
1307 bool Changed = false;
1308 if (!Trunc.hasNoSignedWrap() &&
1309 ComputeMaxSignificantBits(Op: Src, CxtI: &Trunc) <= DestWidth) {
1310 Trunc.setHasNoSignedWrap(true);
1311 Changed = true;
1312 }
1313 if (!Trunc.hasNoUnsignedWrap() &&
1314 MaskedValueIsZero(V: Src, Mask: APInt::getBitsSetFrom(numBits: SrcWidth, loBit: DestWidth),
1315 CxtI: &Trunc)) {
1316 Trunc.setHasNoUnsignedWrap(true);
1317 Changed = true;
1318 }
1319
1320 const APInt *C1;
1321 Value *V1;
1322 // OP = { lshr, ashr }
1323 // trunc ( OP i8 C1, V1) to i1 -> icmp eq V1, log_2(C1) iff C1 is power of 2
1324 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_Power2(V&: C1), R: m_Value(V&: V1)))) {
1325 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1326 return new ICmpInst(ICmpInst::ICMP_EQ, V1, Right);
1327 }
1328
1329 // OP = { lshr, ashr }
1330 // trunc ( OP i8 C1, V1) to i1 -> icmp ult V1, log_2(C1 + 1) iff (C1 + 1) is
1331 // power of 2
1332 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_LowBitMask(V&: C1), R: m_Value(V&: V1)))) {
1333 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_one());
1334 return new ICmpInst(ICmpInst::ICMP_ULT, V1, Right);
1335 }
1336
1337 // OP = { lshr, ashr }
1338 // trunc ( OP i8 C1, V1) to i1 -> icmp ugt V1, cttz(C1) - 1 iff (C1) is
1339 // negative power of 2
1340 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_NegatedPower2(V&: C1), R: m_Value(V&: V1)))) {
1341 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1342 return new ICmpInst(ICmpInst::ICMP_UGE, V1, Right);
1343 }
1344
1345 return Changed ? &Trunc : nullptr;
1346}
1347
1348Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp,
1349 ZExtInst &Zext) {
1350 // If we are just checking for a icmp eq of a single bit and zext'ing it
1351 // to an integer, then shift the bit to the appropriate place and then
1352 // cast to integer to avoid the comparison.
1353
1354 // FIXME: This set of transforms does not check for extra uses and/or creates
1355 // an extra instruction (an optional final cast is not included
1356 // in the transform comments). We may also want to favor icmp over
1357 // shifts in cases of equal instructions because icmp has better
1358 // analysis in general (invert the transform).
1359
1360 const APInt *Op1CV;
1361 if (match(V: Cmp->getOperand(i_nocapture: 1), P: m_APInt(Res&: Op1CV))) {
1362
1363 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
1364 if (Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) {
1365 Value *In = Cmp->getOperand(i_nocapture: 0);
1366 Value *Sh = ConstantInt::get(Ty: In->getType(),
1367 V: In->getType()->getScalarSizeInBits() - 1);
1368 In = Builder.CreateLShr(LHS: In, RHS: Sh, Name: In->getName() + ".lobit");
1369 if (In->getType() != Zext.getType())
1370 In = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false /*ZExt*/);
1371
1372 return replaceInstUsesWith(I&: Zext, V: In);
1373 }
1374
1375 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
1376 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
1377 // zext (X != 0) to i32 --> X iff X has only the low bit set.
1378 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
1379
1380 if (Op1CV->isZero() && Cmp->isEquality()) {
1381 // Exactly 1 possible 1? But not the high-bit because that is
1382 // canonicalized to this form.
1383 KnownBits Known = computeKnownBits(V: Cmp->getOperand(i_nocapture: 0), CxtI: &Zext);
1384 APInt KnownZeroMask(~Known.Zero);
1385 uint32_t ShAmt = KnownZeroMask.logBase2();
1386 bool IsExpectShAmt = KnownZeroMask.isPowerOf2() &&
1387 (Zext.getType()->getScalarSizeInBits() != ShAmt + 1);
1388 if (IsExpectShAmt &&
1389 (Cmp->getOperand(i_nocapture: 0)->getType() == Zext.getType() ||
1390 Cmp->getPredicate() == ICmpInst::ICMP_NE || ShAmt == 0)) {
1391 Value *In = Cmp->getOperand(i_nocapture: 0);
1392 if (ShAmt) {
1393 // Perform a logical shr by shiftamt.
1394 // Insert the shift to put the result in the low bit.
1395 In = Builder.CreateLShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: ShAmt),
1396 Name: In->getName() + ".lobit");
1397 }
1398
1399 // Toggle the low bit for "X == 0".
1400 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1401 In = Builder.CreateXor(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: 1));
1402
1403 if (Zext.getType() == In->getType())
1404 return replaceInstUsesWith(I&: Zext, V: In);
1405
1406 Value *IntCast = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false);
1407 return replaceInstUsesWith(I&: Zext, V: IntCast);
1408 }
1409 }
1410 }
1411
1412 if (Cmp->isEquality()) {
1413 // Test if a bit is clear/set using a shifted-one mask:
1414 // zext (icmp eq (and X, (1 << ShAmt)), 0) --> and (lshr (not X), ShAmt), 1
1415 // zext (icmp ne (and X, (1 << ShAmt)), 0) --> and (lshr X, ShAmt), 1
1416 Value *X, *ShAmt;
1417 if (Cmp->hasOneUse() && match(V: Cmp->getOperand(i_nocapture: 1), P: m_ZeroInt()) &&
1418 match(V: Cmp->getOperand(i_nocapture: 0),
1419 P: m_OneUse(SubPattern: m_c_And(L: m_Shl(L: m_One(), R: m_Value(V&: ShAmt)), R: m_Value(V&: X))))) {
1420 auto *And = cast<BinaryOperator>(Val: Cmp->getOperand(i_nocapture: 0));
1421 Value *Shift = And->getOperand(i_nocapture: X == And->getOperand(i_nocapture: 0) ? 1 : 0);
1422 if (Zext.getType() == And->getType() ||
1423 Cmp->getPredicate() != ICmpInst::ICMP_EQ || Shift->hasOneUse()) {
1424 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1425 X = Builder.CreateNot(V: X);
1426 Value *Lshr = Builder.CreateLShr(LHS: X, RHS: ShAmt);
1427 Value *And1 =
1428 Builder.CreateAnd(LHS: Lshr, RHS: ConstantInt::get(Ty: X->getType(), V: 1));
1429 return replaceInstUsesWith(
1430 I&: Zext, V: Builder.CreateZExtOrTrunc(V: And1, DestTy: Zext.getType()));
1431 }
1432 }
1433 }
1434
1435 return nullptr;
1436}
1437
1438/// Determine if the specified value can be computed in the specified wider type
1439/// and produce the same low bits. If not, return false.
1440///
1441/// If this function returns true, it can also return a non-zero number of bits
1442/// (in BitsToClear) which indicates that the value it computes is correct for
1443/// the zero extend, but that the additional BitsToClear bits need to be zero'd
1444/// out. For example, to promote something like:
1445///
1446/// %B = trunc i64 %A to i32
1447/// %C = lshr i32 %B, 8
1448/// %E = zext i32 %C to i64
1449///
1450/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
1451/// set to 8 to indicate that the promoted value needs to have bits 24-31
1452/// cleared in addition to bits 32-63. Since an 'and' will be generated to
1453/// clear the top bits anyway, doing this has no extra cost.
1454///
1455/// This function works on both vectors and scalars.
1456bool TypeEvaluationHelper::canEvaluateZExtd(Value *V, Type *Ty,
1457 unsigned &BitsToClear,
1458 InstCombinerImpl &IC,
1459 Instruction *CxtI) {
1460 TypeEvaluationHelper TYH;
1461 return TYH.canEvaluateZExtdImpl(V, Ty, BitsToClear, IC, CxtI);
1462}
1463bool TypeEvaluationHelper::canEvaluateZExtdImpl(Value *V, Type *Ty,
1464 unsigned &BitsToClear,
1465 InstCombinerImpl &IC,
1466 Instruction *CxtI) {
1467 BitsToClear = 0;
1468 if (canAlwaysEvaluateInType(V, Ty))
1469 return true;
1470 // We stick to the one-user limit for the ZExt transform due to the fact
1471 // that this predicate returns two values: predicate result and BitsToClear.
1472 if (canNotEvaluateInType(V, Ty))
1473 return false;
1474
1475 auto *I = cast<Instruction>(Val: V);
1476 unsigned Tmp;
1477 switch (I->getOpcode()) {
1478 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
1479 case Instruction::SExt: // zext(sext(x)) -> sext(x).
1480 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
1481 return true;
1482 case Instruction::And:
1483 case Instruction::Or:
1484 case Instruction::Xor:
1485 case Instruction::Add:
1486 case Instruction::Sub:
1487 case Instruction::Mul:
1488 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI) ||
1489 !canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CxtI))
1490 return false;
1491 // These can all be promoted if neither operand has 'bits to clear'.
1492 if (BitsToClear == 0 && Tmp == 0)
1493 return true;
1494
1495 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1496 // other side, BitsToClear is ok.
1497 if (Tmp == 0 && I->isBitwiseLogicOp()) {
1498 // We use MaskedValueIsZero here for generality, but the case we care
1499 // about the most is constant RHS.
1500 unsigned VSize = V->getType()->getScalarSizeInBits();
1501 if (IC.MaskedValueIsZero(V: I->getOperand(i: 1),
1502 Mask: APInt::getHighBitsSet(numBits: VSize, hiBitsSet: BitsToClear),
1503 CxtI)) {
1504 // If this is an And instruction and all of the BitsToClear are
1505 // known to be zero we can reset BitsToClear.
1506 if (I->getOpcode() == Instruction::And)
1507 BitsToClear = 0;
1508 return true;
1509 }
1510 }
1511
1512 // Otherwise, we don't know how to analyze this BitsToClear case yet.
1513 return false;
1514
1515 case Instruction::Shl: {
1516 // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1517 // upper bits we can reduce BitsToClear by the shift amount.
1518 uint64_t ShiftAmt;
1519 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1520 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI))
1521 return false;
1522 BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1523 return true;
1524 }
1525 return false;
1526 }
1527 case Instruction::LShr: {
1528 // We can promote lshr(x, cst) if we can promote x. This requires the
1529 // ultimate 'and' to clear out the high zero bits we're clearing out though.
1530 uint64_t ShiftAmt;
1531 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1532 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CxtI))
1533 return false;
1534 BitsToClear += ShiftAmt;
1535 if (BitsToClear > V->getType()->getScalarSizeInBits())
1536 BitsToClear = V->getType()->getScalarSizeInBits();
1537 return true;
1538 }
1539 // Cannot promote variable LSHR.
1540 return false;
1541 }
1542 case Instruction::Select:
1543 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CxtI) ||
1544 !canEvaluateZExtdImpl(V: I->getOperand(i: 2), Ty, BitsToClear, IC, CxtI) ||
1545 // TODO: If important, we could handle the case when the BitsToClear are
1546 // known zero in the disagreeing side.
1547 Tmp != BitsToClear)
1548 return false;
1549 return true;
1550
1551 case Instruction::PHI: {
1552 // We can change a phi if we can change all operands. Note that we never
1553 // get into trouble with cyclic PHIs here because we only consider
1554 // instructions with a single use.
1555 PHINode *PN = cast<PHINode>(Val: I);
1556 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i: 0), Ty, BitsToClear, IC,
1557 CxtI))
1558 return false;
1559 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1560 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i), Ty, BitsToClear&: Tmp, IC, CxtI) ||
1561 // TODO: If important, we could handle the case when the BitsToClear
1562 // are known zero in the disagreeing input.
1563 Tmp != BitsToClear)
1564 return false;
1565 return true;
1566 }
1567 case Instruction::Call:
1568 // llvm.vscale() can always be executed in larger type, because the
1569 // value is automatically zero-extended.
1570 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I))
1571 if (II->getIntrinsicID() == Intrinsic::vscale)
1572 return true;
1573 return false;
1574 default:
1575 // TODO: Can handle more cases here.
1576 return false;
1577 }
1578}
1579
1580Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
1581 // If this zero extend is only used by a truncate, let the truncate be
1582 // eliminated before we try to optimize this zext.
1583 if (Zext.hasOneUse() && isa<TruncInst>(Val: Zext.user_back()) &&
1584 !isa<Constant>(Val: Zext.getOperand(i_nocapture: 0)))
1585 return nullptr;
1586
1587 // If one of the common conversion will work, do it.
1588 if (Instruction *Result = commonCastTransforms(CI&: Zext))
1589 return Result;
1590
1591 if (auto *NewI = foldExtractionOfVectorDeinterleave(RootZExt&: Zext))
1592 return NewI;
1593
1594 Value *Src = Zext.getOperand(i_nocapture: 0);
1595 Type *SrcTy = Src->getType(), *DestTy = Zext.getType();
1596
1597 // zext nneg bool x -> 0
1598 if (SrcTy->isIntOrIntVectorTy(BitWidth: 1) && Zext.hasNonNeg())
1599 return replaceInstUsesWith(I&: Zext, V: Constant::getNullValue(Ty: Zext.getType()));
1600
1601 // Try to extend the entire expression tree to the wide destination type.
1602 unsigned BitsToClear;
1603 if (shouldChangeType(From: SrcTy, To: DestTy) &&
1604 TypeEvaluationHelper::canEvaluateZExtd(V: Src, Ty: DestTy, BitsToClear, IC&: *this,
1605 CxtI: &Zext)) {
1606 assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1607 "Can't clear more bits than in SrcTy");
1608
1609 // Okay, we can transform this! Insert the new expression now.
1610 LLVM_DEBUG(
1611 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1612 " to avoid zero extend: "
1613 << Zext << '\n');
1614 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: false);
1615 assert(Res->getType() == DestTy);
1616
1617 // Preserve debug values referring to Src if the zext is its last use.
1618 if (auto *SrcOp = dyn_cast<Instruction>(Val: Src))
1619 if (SrcOp->hasOneUse())
1620 replaceAllDbgUsesWith(From&: *SrcOp, To&: *Res, DomPoint&: Zext, DT);
1621
1622 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits() - BitsToClear;
1623 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1624
1625 // If the high bits are already filled with zeros, just replace this
1626 // cast with the result.
1627 if (MaskedValueIsZero(
1628 V: Res, Mask: APInt::getHighBitsSet(numBits: DestBitSize, hiBitsSet: DestBitSize - SrcBitsKept),
1629 CxtI: &Zext))
1630 return replaceInstUsesWith(I&: Zext, V: Res);
1631
1632 // We need to emit an AND to clear the high bits.
1633 Constant *C = ConstantInt::get(Ty: Res->getType(),
1634 V: APInt::getLowBitsSet(numBits: DestBitSize, loBitsSet: SrcBitsKept));
1635 return BinaryOperator::CreateAnd(V1: Res, V2: C);
1636 }
1637
1638 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1639 // types and if the sizes are just right we can convert this into a logical
1640 // 'and' which will be much cheaper than the pair of casts.
1641 if (auto *CSrc = dyn_cast<TruncInst>(Val: Src)) { // A->B->C cast
1642 // TODO: Subsume this into EvaluateInDifferentType.
1643
1644 // Get the sizes of the types involved. We know that the intermediate type
1645 // will be smaller than A or C, but don't know the relation between A and C.
1646 Value *A = CSrc->getOperand(i_nocapture: 0);
1647 unsigned SrcSize = A->getType()->getScalarSizeInBits();
1648 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1649 unsigned DstSize = DestTy->getScalarSizeInBits();
1650 // If we're actually extending zero bits, then if
1651 // SrcSize < DstSize: zext(a & mask)
1652 // SrcSize == DstSize: a & mask
1653 // SrcSize > DstSize: trunc(a) & mask
1654 if (SrcSize < DstSize) {
1655 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1656 Constant *AndConst = ConstantInt::get(Ty: A->getType(), V: AndValue);
1657 Value *And = Builder.CreateAnd(LHS: A, RHS: AndConst, Name: CSrc->getName() + ".mask");
1658 return new ZExtInst(And, DestTy);
1659 }
1660
1661 if (SrcSize == DstSize) {
1662 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1663 return BinaryOperator::CreateAnd(V1: A, V2: ConstantInt::get(Ty: A->getType(),
1664 V: AndValue));
1665 }
1666 if (SrcSize > DstSize) {
1667 Value *Trunc = Builder.CreateTrunc(V: A, DestTy);
1668 APInt AndValue(APInt::getLowBitsSet(numBits: DstSize, loBitsSet: MidSize));
1669 return BinaryOperator::CreateAnd(V1: Trunc,
1670 V2: ConstantInt::get(Ty: Trunc->getType(),
1671 V: AndValue));
1672 }
1673 }
1674
1675 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1676 return transformZExtICmp(Cmp, Zext);
1677
1678 Constant *C;
1679 Value *X;
1680 // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1681 Value *And;
1682 if (match(V: Src, P: m_OneUse(SubPattern: m_Xor(L: m_Value(V&: And), R: m_Constant(C)))) &&
1683 match(V: And, P: m_OneUse(SubPattern: m_And(L: m_Trunc(Op: m_Value(V&: X)), R: m_Specific(V: C)))) &&
1684 X->getType() == DestTy) {
1685 Value *ZC = Builder.CreateZExt(V: C, DestTy);
1686 return BinaryOperator::CreateXor(V1: Builder.CreateAnd(LHS: X, RHS: ZC), V2: ZC);
1687 }
1688
1689 // If we are truncating, masking, and then zexting back to the original type,
1690 // that's just a mask. This is not handled by canEvaluateZextd if the
1691 // intermediate values have extra uses. This could be generalized further for
1692 // a non-constant mask operand.
1693 // zext (and (trunc X), C) --> and X, (zext C)
1694 if (match(V: Src, P: m_And(L: m_Trunc(Op: m_Value(V&: X)), R: m_Constant(C))) &&
1695 X->getType() == DestTy) {
1696 Value *ZextC = Builder.CreateZExt(V: C, DestTy);
1697 return BinaryOperator::CreateAnd(V1: X, V2: ZextC);
1698 }
1699
1700 Value *Y;
1701 if (match(V: Src,
1702 P: m_OneUse(SubPattern: m_c_BitwiseLogic(L: m_NUWTrunc(Op: m_Value(V&: X)), R: m_Value(V&: Y)))) &&
1703 X->getType() == DestTy) {
1704 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
1705 return BinaryOperator::Create(Op: cast<BinaryOperator>(Val: Src)->getOpcode(), S1: X,
1706 S2: ZextY);
1707 }
1708
1709 if (match(V: Src, P: m_VScale())) {
1710 if (Zext.getFunction() &&
1711 Zext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1712 Attribute Attr =
1713 Zext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1714 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
1715 unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
1716 if (Log2_32(Value: *MaxVScale) < TypeWidth)
1717 return replaceInstUsesWith(I&: Zext, V: Builder.CreateVScale(Ty: DestTy));
1718 }
1719 }
1720 }
1721
1722 if (!Zext.hasNonNeg()) {
1723 // If this zero extend is only used by a shift, add nneg flag.
1724 if (Zext.hasOneUse() &&
1725 SrcTy->getScalarSizeInBits() >
1726 Log2_64_Ceil(Value: DestTy->getScalarSizeInBits()) &&
1727 match(V: Zext.user_back(), P: m_Shift(L: m_Value(), R: m_Specific(V: &Zext)))) {
1728 Zext.setNonNeg();
1729 return &Zext;
1730 }
1731
1732 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Zext))) {
1733 Zext.setNonNeg();
1734 return &Zext;
1735 }
1736 }
1737
1738 return nullptr;
1739}
1740
1741/// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1742Instruction *InstCombinerImpl::transformSExtICmp(ICmpInst *Cmp,
1743 SExtInst &Sext) {
1744 Value *Op0 = Cmp->getOperand(i_nocapture: 0), *Op1 = Cmp->getOperand(i_nocapture: 1);
1745 ICmpInst::Predicate Pred = Cmp->getPredicate();
1746
1747 // Don't bother if Op1 isn't of vector or integer type.
1748 if (!Op1->getType()->isIntOrIntVectorTy())
1749 return nullptr;
1750
1751 if (Pred == ICmpInst::ICMP_SLT && match(V: Op1, P: m_ZeroInt())) {
1752 // sext (x <s 0) --> ashr x, 31 (all ones if negative)
1753 Value *Sh = ConstantInt::get(Ty: Op0->getType(),
1754 V: Op0->getType()->getScalarSizeInBits() - 1);
1755 Value *In = Builder.CreateAShr(LHS: Op0, RHS: Sh, Name: Op0->getName() + ".lobit");
1756 if (In->getType() != Sext.getType())
1757 In = Builder.CreateIntCast(V: In, DestTy: Sext.getType(), isSigned: true /*SExt*/);
1758
1759 return replaceInstUsesWith(I&: Sext, V: In);
1760 }
1761
1762 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Val: Op1)) {
1763 // If we know that only one bit of the LHS of the icmp can be set and we
1764 // have an equality comparison with zero or a power of 2, we can transform
1765 // the icmp and sext into bitwise/integer operations.
1766 if (Cmp->hasOneUse() &&
1767 Cmp->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1768 KnownBits Known = computeKnownBits(V: Op0, CxtI: &Sext);
1769
1770 APInt KnownZeroMask(~Known.Zero);
1771 if (KnownZeroMask.isPowerOf2()) {
1772 Value *In = Cmp->getOperand(i_nocapture: 0);
1773
1774 // If the icmp tests for a known zero bit we can constant fold it.
1775 if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1776 Value *V = Pred == ICmpInst::ICMP_NE ?
1777 ConstantInt::getAllOnesValue(Ty: Sext.getType()) :
1778 ConstantInt::getNullValue(Ty: Sext.getType());
1779 return replaceInstUsesWith(I&: Sext, V);
1780 }
1781
1782 if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1783 // sext ((x & 2^n) == 0) -> (x >> n) - 1
1784 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1785 unsigned ShiftAmt = KnownZeroMask.countr_zero();
1786 // Perform a right shift to place the desired bit in the LSB.
1787 if (ShiftAmt)
1788 In = Builder.CreateLShr(LHS: In,
1789 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1790
1791 // At this point "In" is either 1 or 0. Subtract 1 to turn
1792 // {1, 0} -> {0, -1}.
1793 In = Builder.CreateAdd(LHS: In,
1794 RHS: ConstantInt::getAllOnesValue(Ty: In->getType()),
1795 Name: "sext");
1796 } else {
1797 // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1798 // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1799 unsigned ShiftAmt = KnownZeroMask.countl_zero();
1800 // Perform a left shift to place the desired bit in the MSB.
1801 if (ShiftAmt)
1802 In = Builder.CreateShl(LHS: In,
1803 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1804
1805 // Distribute the bit over the whole bit width.
1806 In = Builder.CreateAShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(),
1807 V: KnownZeroMask.getBitWidth() - 1), Name: "sext");
1808 }
1809
1810 if (Sext.getType() == In->getType())
1811 return replaceInstUsesWith(I&: Sext, V: In);
1812 return CastInst::CreateIntegerCast(S: In, Ty: Sext.getType(), isSigned: true/*SExt*/);
1813 }
1814 }
1815 }
1816
1817 return nullptr;
1818}
1819
1820/// Return true if we can take the specified value and return it as type Ty
1821/// without inserting any new casts and without changing the value of the common
1822/// low bits. This is used by code that tries to promote integer operations to
1823/// a wider types will allow us to eliminate the extension.
1824///
1825/// This function works on both vectors and scalars.
1826///
1827bool TypeEvaluationHelper::canEvaluateSExtd(Value *V, Type *Ty) {
1828 TypeEvaluationHelper TYH;
1829 return TYH.canEvaluateSExtdImpl(V, Ty) && TYH.allPendingVisited();
1830}
1831
1832bool TypeEvaluationHelper::canEvaluateSExtdImpl(Value *V, Type *Ty) {
1833 return canEvaluate(V, Ty, Pred: [this](Value *V, Type *Ty) {
1834 return canEvaluateSExtdPred(V, Ty);
1835 });
1836}
1837
1838bool TypeEvaluationHelper::canEvaluateSExtdPred(Value *V, Type *Ty) {
1839 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
1840 "Can't sign extend type to a smaller type");
1841
1842 auto *I = cast<Instruction>(Val: V);
1843 switch (I->getOpcode()) {
1844 case Instruction::SExt: // sext(sext(x)) -> sext(x)
1845 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1846 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1847 return true;
1848 case Instruction::And:
1849 case Instruction::Or:
1850 case Instruction::Xor:
1851 case Instruction::Add:
1852 case Instruction::Sub:
1853 case Instruction::Mul:
1854 // These operators can all arbitrarily be extended if their inputs can.
1855 return canEvaluateSExtdImpl(V: I->getOperand(i: 0), Ty) &&
1856 canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty);
1857
1858 // case Instruction::Shl: TODO
1859 // case Instruction::LShr: TODO
1860
1861 case Instruction::Select:
1862 return canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty) &&
1863 canEvaluateSExtdImpl(V: I->getOperand(i: 2), Ty);
1864
1865 case Instruction::PHI: {
1866 // We can change a phi if we can change all operands. Note that we never
1867 // get into trouble with cyclic PHIs here because canEvaluate handles use
1868 // chain loops.
1869 PHINode *PN = cast<PHINode>(Val: I);
1870 for (Value *IncValue : PN->incoming_values())
1871 if (!canEvaluateSExtdImpl(V: IncValue, Ty))
1872 return false;
1873 return true;
1874 }
1875 default:
1876 // TODO: Can handle more cases here.
1877 break;
1878 }
1879
1880 return false;
1881}
1882
1883Instruction *InstCombinerImpl::visitSExt(SExtInst &Sext) {
1884 // If this sign extend is only used by a truncate, let the truncate be
1885 // eliminated before we try to optimize this sext.
1886 if (Sext.hasOneUse() && isa<TruncInst>(Val: Sext.user_back()))
1887 return nullptr;
1888
1889 if (Instruction *I = commonCastTransforms(CI&: Sext))
1890 return I;
1891
1892 Value *Src = Sext.getOperand(i_nocapture: 0);
1893 Type *SrcTy = Src->getType(), *DestTy = Sext.getType();
1894 unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1895 unsigned DestBitSize = DestTy->getScalarSizeInBits();
1896
1897 // If the value being extended is zero or positive, use a zext instead.
1898 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Sext))) {
1899 auto CI = CastInst::Create(Instruction::ZExt, S: Src, Ty: DestTy);
1900 CI->setNonNeg(true);
1901 return CI;
1902 }
1903
1904 // Try to extend the entire expression tree to the wide destination type.
1905 bool ShouldExtendExpression = true;
1906 Value *TruncSrc = nullptr;
1907 // It is not desirable to extend expression in the trunc + sext pattern when
1908 // destination type is narrower than original (pre-trunc) type.
1909 if (match(V: Src, P: m_Trunc(Op: m_Value(V&: TruncSrc))))
1910 if (TruncSrc->getType()->getScalarSizeInBits() > DestBitSize)
1911 ShouldExtendExpression = false;
1912 if (ShouldExtendExpression && shouldChangeType(From: SrcTy, To: DestTy) &&
1913 TypeEvaluationHelper::canEvaluateSExtd(V: Src, Ty: DestTy)) {
1914 // Okay, we can transform this! Insert the new expression now.
1915 LLVM_DEBUG(
1916 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1917 " to avoid sign extend: "
1918 << Sext << '\n');
1919 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: true);
1920 assert(Res->getType() == DestTy);
1921
1922 // If the high bits are already filled with sign bit, just replace this
1923 // cast with the result.
1924 if (ComputeNumSignBits(Op: Res, CxtI: &Sext) > DestBitSize - SrcBitSize)
1925 return replaceInstUsesWith(I&: Sext, V: Res);
1926
1927 // We need to emit a shl + ashr to do the sign extend.
1928 Value *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
1929 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: Res, RHS: ShAmt, Name: "sext"),
1930 V2: ShAmt);
1931 }
1932
1933 Value *X = TruncSrc;
1934 if (X) {
1935 // If the input has more sign bits than bits truncated, then convert
1936 // directly to final type.
1937 unsigned XBitSize = X->getType()->getScalarSizeInBits();
1938 bool HasNSW = cast<TruncInst>(Val: Src)->hasNoSignedWrap();
1939 if (HasNSW || (ComputeNumSignBits(Op: X, CxtI: &Sext) > XBitSize - SrcBitSize)) {
1940 auto *Res = CastInst::CreateIntegerCast(S: X, Ty: DestTy, /* isSigned */ true);
1941 if (auto *ResTrunc = dyn_cast<TruncInst>(Val: Res); ResTrunc && HasNSW)
1942 ResTrunc->setHasNoSignedWrap(true);
1943 return Res;
1944 }
1945
1946 // If input is a trunc from the destination type, then convert into shifts.
1947 if (Src->hasOneUse() && X->getType() == DestTy) {
1948 // sext (trunc X) --> ashr (shl X, C), C
1949 Constant *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
1950 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShAmt), V2: ShAmt);
1951 }
1952
1953 // If we are replacing shifted-in high zero bits with sign bits, convert
1954 // the logic shift to arithmetic shift and eliminate the cast to
1955 // intermediate type:
1956 // sext (trunc (lshr Y, C)) --> sext/trunc (ashr Y, C)
1957 Value *Y;
1958 if (Src->hasOneUse() &&
1959 match(V: X, P: m_LShr(L: m_Value(V&: Y),
1960 R: m_SpecificIntAllowPoison(V: XBitSize - SrcBitSize)))) {
1961 Value *Ashr = Builder.CreateAShr(LHS: Y, RHS: XBitSize - SrcBitSize);
1962 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
1963 }
1964 }
1965
1966 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1967 return transformSExtICmp(Cmp, Sext);
1968
1969 // If the input is a shl/ashr pair of a same constant, then this is a sign
1970 // extension from a smaller value. If we could trust arbitrary bitwidth
1971 // integers, we could turn this into a truncate to the smaller bit and then
1972 // use a sext for the whole extension. Since we don't, look deeper and check
1973 // for a truncate. If the source and dest are the same type, eliminate the
1974 // trunc and extend and just do shifts. For example, turn:
1975 // %a = trunc i32 %i to i8
1976 // %b = shl i8 %a, C
1977 // %c = ashr i8 %b, C
1978 // %d = sext i8 %c to i32
1979 // into:
1980 // %a = shl i32 %i, 32-(8-C)
1981 // %d = ashr i32 %a, 32-(8-C)
1982 Value *A = nullptr;
1983 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1984 Constant *BA = nullptr, *CA = nullptr;
1985 if (match(V: Src, P: m_AShr(L: m_Shl(L: m_Trunc(Op: m_Value(V&: A)), R: m_Constant(C&: BA)),
1986 R: m_ImmConstant(C&: CA))) &&
1987 BA->isElementWiseEqual(Y: CA) && A->getType() == DestTy) {
1988 Constant *WideCurrShAmt =
1989 ConstantFoldCastOperand(Opcode: Instruction::SExt, C: CA, DestTy, DL);
1990 assert(WideCurrShAmt && "Constant folding of ImmConstant cannot fail");
1991 Constant *NumLowbitsLeft = ConstantExpr::getSub(
1992 C1: ConstantInt::get(Ty: DestTy, V: SrcTy->getScalarSizeInBits()), C2: WideCurrShAmt);
1993 Constant *NewShAmt = ConstantExpr::getSub(
1994 C1: ConstantInt::get(Ty: DestTy, V: DestTy->getScalarSizeInBits()),
1995 C2: NumLowbitsLeft);
1996 NewShAmt =
1997 Constant::mergeUndefsWith(C: Constant::mergeUndefsWith(C: NewShAmt, Other: BA), Other: CA);
1998 A = Builder.CreateShl(LHS: A, RHS: NewShAmt, Name: Sext.getName());
1999 return BinaryOperator::CreateAShr(V1: A, V2: NewShAmt);
2000 }
2001
2002 // Splatting a bit of constant-index across a value:
2003 // sext (ashr (trunc iN X to iM), M-1) to iN --> ashr (shl X, N-M), N-1
2004 // If the dest type is different, use a cast (adjust use check).
2005 if (match(V: Src, P: m_OneUse(SubPattern: m_AShr(L: m_Trunc(Op: m_Value(V&: X)),
2006 R: m_SpecificInt(V: SrcBitSize - 1))))) {
2007 Type *XTy = X->getType();
2008 unsigned XBitSize = XTy->getScalarSizeInBits();
2009 Constant *ShlAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - SrcBitSize);
2010 Constant *AshrAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - 1);
2011 if (XTy == DestTy)
2012 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShlAmtC),
2013 V2: AshrAmtC);
2014 if (cast<BinaryOperator>(Val: Src)->getOperand(i_nocapture: 0)->hasOneUse()) {
2015 Value *Ashr = Builder.CreateAShr(LHS: Builder.CreateShl(LHS: X, RHS: ShlAmtC), RHS: AshrAmtC);
2016 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
2017 }
2018 }
2019
2020 if (match(V: Src, P: m_VScale())) {
2021 if (Sext.getFunction() &&
2022 Sext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
2023 Attribute Attr =
2024 Sext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
2025 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
2026 if (Log2_32(Value: *MaxVScale) < (SrcBitSize - 1))
2027 return replaceInstUsesWith(I&: Sext, V: Builder.CreateVScale(Ty: DestTy));
2028 }
2029 }
2030
2031 // sext(scmp(x, y)) -> scmp(x, y) with a wider result type.
2032 // sext(ucmp(x, y)) -> ucmp(x, y) with a wider result type.
2033 // scmp/ucmp return only -1, 0, or 1, which sign-extend correctly to any
2034 // wider integer type, so we can sink the extension into the intrinsic.
2035 if (auto *CI = dyn_cast<CmpIntrinsic>(Val: Src); CI && CI->hasOneUse())
2036 return replaceInstUsesWith(
2037 I&: Sext, V: Builder.CreateIntrinsic(RetTy: DestTy, ID: CI->getIntrinsicID(),
2038 Args: {CI->getLHS(), CI->getRHS()}));
2039
2040 Value *Y;
2041 if (match(V: Src,
2042 P: m_OneUse(SubPattern: m_c_BitwiseLogic(L: m_NSWTrunc(Op: m_Value(V&: X)), R: m_Value(V&: Y)))) &&
2043 X->getType() == DestTy) {
2044 Value *SextY = Builder.CreateSExt(V: Y, DestTy);
2045 return BinaryOperator::Create(Op: cast<BinaryOperator>(Val: Src)->getOpcode(), S1: X,
2046 S2: SextY);
2047 }
2048
2049 return nullptr;
2050}
2051
2052/// Return a Constant* for the specified floating-point constant if it fits
2053/// in the specified FP type without changing its value.
2054static bool fitsInFPType(APFloat F, const fltSemantics &Sem) {
2055 bool losesInfo;
2056 (void)F.convert(ToSemantics: Sem, RM: APFloat::rmNearestTiesToEven, losesInfo: &losesInfo);
2057 return !losesInfo;
2058}
2059
2060static Type *shrinkFPConstant(LLVMContext &Ctx, const APFloat &F,
2061 bool PreferBFloat) {
2062 // See if the value can be truncated to bfloat and then reextended.
2063 if (PreferBFloat && fitsInFPType(F, Sem: APFloat::BFloat()))
2064 return Type::getBFloatTy(C&: Ctx);
2065 // See if the value can be truncated to half and then reextended.
2066 if (!PreferBFloat && fitsInFPType(F, Sem: APFloat::IEEEhalf()))
2067 return Type::getHalfTy(C&: Ctx);
2068 // See if the value can be truncated to float and then reextended.
2069 if (fitsInFPType(F, Sem: APFloat::IEEEsingle()))
2070 return Type::getFloatTy(C&: Ctx);
2071 if (&F.getSemantics() == &APFloat::IEEEdouble())
2072 return nullptr; // Won't shrink.
2073 // See if the value can be truncated to double and then reextended.
2074 if (fitsInFPType(F, Sem: APFloat::IEEEdouble()))
2075 return Type::getDoubleTy(C&: Ctx);
2076 // Don't try to shrink to various long double types.
2077 return nullptr;
2078}
2079
2080static Type *shrinkFPConstant(ConstantFP *CFP, bool PreferBFloat) {
2081 Type *Ty = CFP->getType();
2082 if (Ty->getScalarType()->isPPC_FP128Ty())
2083 return nullptr; // No constant folding of this.
2084
2085 Type *ShrinkTy =
2086 shrinkFPConstant(Ctx&: CFP->getContext(), F: CFP->getValueAPF(), PreferBFloat);
2087 if (ShrinkTy)
2088 if (auto *VecTy = dyn_cast<VectorType>(Val: Ty))
2089 ShrinkTy = VectorType::get(ElementType: ShrinkTy, Other: VecTy);
2090
2091 return ShrinkTy;
2092}
2093
2094// Determine if this is a vector of ConstantFPs and if so, return the minimal
2095// type we can safely truncate all elements to.
2096static Type *shrinkFPConstantVector(Value *V, bool PreferBFloat) {
2097 auto *CV = dyn_cast<Constant>(Val: V);
2098 auto *CVVTy = dyn_cast<FixedVectorType>(Val: V->getType());
2099 if (!CV || !CVVTy)
2100 return nullptr;
2101
2102 Type *MinType = nullptr;
2103
2104 unsigned NumElts = CVVTy->getNumElements();
2105
2106 // For fixed-width vectors we find the minimal type by looking
2107 // through the constant values of the vector.
2108 for (unsigned I = 0; I != NumElts; ++I) {
2109 if (match(V: CV->getAggregateElement(Elt: I), P: m_Poison()))
2110 continue;
2111
2112 auto *CFP = dyn_cast_or_null<ConstantFP>(Val: CV->getAggregateElement(Elt: I));
2113 if (!CFP)
2114 return nullptr;
2115
2116 Type *T = shrinkFPConstant(CFP, PreferBFloat);
2117 if (!T)
2118 return nullptr;
2119
2120 // If we haven't found a type yet or this type has a larger mantissa than
2121 // our previous type, this is our new minimal type.
2122 if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
2123 MinType = T;
2124 }
2125
2126 // Make a vector type from the minimal type.
2127 return MinType ? FixedVectorType::get(ElementType: MinType, NumElts) : nullptr;
2128}
2129
2130/// Find the minimum FP type we can safely truncate to.
2131static Type *getMinimumFPType(Value *V, Type *PreferredTy, InstCombiner &IC) {
2132 if (auto *FPExt = dyn_cast<FPExtInst>(Val: V))
2133 return FPExt->getOperand(i_nocapture: 0)->getType();
2134
2135 Value *Src;
2136 if (match(V, P: m_IToFP(Op: m_Value(V&: Src))) &&
2137 IC.canBeCastedExactlyIntToFP(V: Src, FPTy: PreferredTy, IsSigned: isa<SIToFPInst>(Val: V),
2138 CxtI: cast<Instruction>(Val: V)))
2139 return PreferredTy;
2140
2141 bool PreferBFloat = PreferredTy->getScalarType()->isBFloatTy();
2142 // If this value is a constant, return the constant in the smallest FP type
2143 // that can accurately represent it. This allows us to turn
2144 // (float)((double)X+2.0) into x+2.0f.
2145 if (auto *CFP = dyn_cast<ConstantFP>(Val: V))
2146 if (Type *T = shrinkFPConstant(CFP, PreferBFloat))
2147 return T;
2148
2149 // Try to shrink scalable and fixed splat vectors.
2150 if (auto *FPC = dyn_cast<Constant>(Val: V))
2151 if (auto *VTy = dyn_cast<VectorType>(Val: V->getType()))
2152 if (auto *Splat = dyn_cast_or_null<ConstantFP>(Val: FPC->getSplatValue()))
2153 if (Type *T = shrinkFPConstant(CFP: Splat, PreferBFloat))
2154 return VectorType::get(ElementType: T, Other: VTy);
2155
2156 // Try to shrink a vector of FP constants. This returns nullptr on scalable
2157 // vectors
2158 if (Type *T = shrinkFPConstantVector(V, PreferBFloat))
2159 return T;
2160
2161 return V->getType();
2162}
2163
2164bool InstCombiner::canBeCastedExactlyIntToFP(Value *V, Type *FPTy,
2165 bool IsSigned,
2166 const Instruction *CxtI) const {
2167 Type *SrcTy = V->getType();
2168 assert(SrcTy->isIntOrIntVectorTy() && "Expected an integer type");
2169 int SrcSize = (int)SrcTy->getScalarSizeInBits() - IsSigned;
2170 int DestNumSigBits = FPTy->getFPMantissaWidth();
2171
2172 // Easy case - if the source integer type has less bits than the FP mantissa,
2173 // then the cast must be exact.
2174 if (SrcSize <= DestNumSigBits)
2175 return true;
2176
2177 // Cast from FP to integer and back to FP is independent of the intermediate
2178 // integer width because of poison on overflow.
2179 Value *F;
2180 if (match(V, P: m_FPToI(Op: m_Value(V&: F)))) {
2181 // If this is uitofp (fptosi F), the source needs an extra bit to avoid
2182 // potential rounding of negative FP input values.
2183 int SrcNumSigBits = F->getType()->getFPMantissaWidth();
2184 if (!IsSigned && match(V, P: m_FPToSI(Op: m_Value())))
2185 SrcNumSigBits++;
2186
2187 // [su]itofp (fpto[su]i F) --> exact if the source type has less or equal
2188 // significant bits than the destination (and make sure neither type is
2189 // weird -- ppc_fp128).
2190 if (SrcNumSigBits > 0 && DestNumSigBits > 0 &&
2191 SrcNumSigBits <= DestNumSigBits)
2192 return true;
2193 }
2194
2195 // Try harder to find if the source integer type has less significant bits.
2196 // Compute number of sign bits or determine trailing zeros.
2197 KnownBits SrcKnown = computeKnownBits(V, CxtI);
2198 int SigBits = (int)SrcTy->getScalarSizeInBits() -
2199 SrcKnown.countMinLeadingZeros() -
2200 SrcKnown.countMinTrailingZeros();
2201 if (SigBits <= DestNumSigBits)
2202 return true;
2203
2204 // For sitofp, the sign maps to the FP sign bit, so only magnitude bits
2205 // (BitWidth - NumSignBits) consume mantissa.
2206 if (IsSigned) {
2207 SigBits = (int)SrcTy->getScalarSizeInBits() - ComputeNumSignBits(Op: V, CxtI);
2208 if (SigBits <= DestNumSigBits)
2209 return true;
2210 }
2211
2212 return false;
2213}
2214
2215bool InstCombiner::isKnownExactCastIntToFP(CastInst &I) const {
2216 CastInst::CastOps Opcode = I.getOpcode();
2217 assert((Opcode == CastInst::SIToFP || Opcode == CastInst::UIToFP) &&
2218 "Unexpected cast");
2219 Value *Src = I.getOperand(i_nocapture: 0);
2220 Type *FPTy = I.getType();
2221 return canBeCastedExactlyIntToFP(V: Src, FPTy, IsSigned: Opcode == CastInst::SIToFP, CxtI: &I);
2222}
2223
2224Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {
2225 if (Instruction *I = commonCastTransforms(CI&: FPT))
2226 return I;
2227
2228 // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
2229 // simplify this expression to avoid one or more of the trunc/extend
2230 // operations if we can do so without changing the numerical results.
2231 //
2232 // The exact manner in which the widths of the operands interact to limit
2233 // what we can and cannot do safely varies from operation to operation, and
2234 // is explained below in the various case statements.
2235 Type *Ty = FPT.getType();
2236 auto *BO = dyn_cast<BinaryOperator>(Val: FPT.getOperand(i_nocapture: 0));
2237 if (BO && BO->hasOneUse()) {
2238 Type *LHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 0), PreferredTy: Ty, IC&: *this);
2239 Type *RHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 1), PreferredTy: Ty, IC&: *this);
2240 unsigned OpWidth = BO->getType()->getFPMantissaWidth();
2241 unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
2242 unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
2243 unsigned SrcWidth = std::max(a: LHSWidth, b: RHSWidth);
2244 unsigned DstWidth = Ty->getFPMantissaWidth();
2245 switch (BO->getOpcode()) {
2246 default: break;
2247 case Instruction::FAdd:
2248 case Instruction::FSub:
2249 // For addition and subtraction, the infinitely precise result can
2250 // essentially be arbitrarily wide; proving that double rounding
2251 // will not occur because the result of OpI is exact (as we will for
2252 // FMul, for example) is hopeless. However, we *can* nonetheless
2253 // frequently know that double rounding cannot occur (or that it is
2254 // innocuous) by taking advantage of the specific structure of
2255 // infinitely-precise results that admit double rounding.
2256 //
2257 // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
2258 // to represent both sources, we can guarantee that the double
2259 // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
2260 // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
2261 // for proof of this fact).
2262 //
2263 // Note: Figueroa does not consider the case where DstFormat !=
2264 // SrcFormat. It's possible (likely even!) that this analysis
2265 // could be tightened for those cases, but they are rare (the main
2266 // case of interest here is (float)((double)float + float)).
2267 if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
2268 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2269 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2270 Instruction *RI = BinaryOperator::Create(Op: BO->getOpcode(), S1: LHS, S2: RHS);
2271 RI->copyFastMathFlags(I: BO);
2272 return RI;
2273 }
2274 break;
2275 case Instruction::FMul:
2276 // For multiplication, the infinitely precise result has at most
2277 // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
2278 // that such a value can be exactly represented, then no double
2279 // rounding can possibly occur; we can safely perform the operation
2280 // in the destination format if it can represent both sources.
2281 if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
2282 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2283 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2284 return BinaryOperator::CreateFMulFMF(V1: LHS, V2: RHS, FMFSource: BO);
2285 }
2286 break;
2287 case Instruction::FDiv:
2288 // For division, we use again use the bound from Figueroa's
2289 // dissertation. I am entirely certain that this bound can be
2290 // tightened in the unbalanced operand case by an analysis based on
2291 // the diophantine rational approximation bound, but the well-known
2292 // condition used here is a good conservative first pass.
2293 // TODO: Tighten bound via rigorous analysis of the unbalanced case.
2294 if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
2295 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2296 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2297 return BinaryOperator::CreateFDivFMF(V1: LHS, V2: RHS, FMFSource: BO);
2298 }
2299 break;
2300 case Instruction::FRem: {
2301 // Remainder is straightforward. Remainder is always exact, so the
2302 // type of OpI doesn't enter into things at all. We simply evaluate
2303 // in whichever source type is larger, then convert to the
2304 // destination type.
2305 if (SrcWidth == OpWidth)
2306 break;
2307 Value *LHS, *RHS;
2308 if (LHSWidth == SrcWidth) {
2309 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: LHSMinType);
2310 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: LHSMinType);
2311 } else {
2312 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: RHSMinType);
2313 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: RHSMinType);
2314 }
2315
2316 Value *ExactResult = Builder.CreateFRemFMF(L: LHS, R: RHS, FMFSource: BO);
2317 return CastInst::CreateFPCast(S: ExactResult, Ty);
2318 }
2319 }
2320 }
2321
2322 // (fptrunc (fneg x)) -> (fneg (fptrunc x))
2323 Value *X;
2324 Instruction *Op = dyn_cast<Instruction>(Val: FPT.getOperand(i_nocapture: 0));
2325 if (Op && Op->hasOneUse()) {
2326 FastMathFlags FMF = FPT.getFastMathFlags();
2327 if (auto *FPMO = dyn_cast<FPMathOperator>(Val: Op))
2328 FMF &= FPMO->getFastMathFlags();
2329
2330 if (match(V: Op, P: m_FNeg(X: m_Value(V&: X)))) {
2331 Value *InnerTrunc = Builder.CreateFPTruncFMF(V: X, DestTy: Ty, FMFSource: FMF);
2332 Value *Neg = Builder.CreateFNegFMF(V: InnerTrunc, FMFSource: FMF);
2333 return replaceInstUsesWith(I&: FPT, V: Neg);
2334 }
2335
2336 // If we are truncating a select that has an extended operand, we can
2337 // narrow the other operand and do the select as a narrow op.
2338 Value *Cond, *X, *Y;
2339 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_FPExt(Op: m_Value(V&: X)), R: m_Value(V&: Y))) &&
2340 X->getType() == Ty) {
2341 // fptrunc (select Cond, (fpext X), Y --> select Cond, X, (fptrunc Y)
2342 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2343 Value *Sel =
2344 Builder.CreateSelectFMF(C: Cond, True: X, False: NarrowY, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2345 return replaceInstUsesWith(I&: FPT, V: Sel);
2346 }
2347 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: Y), R: m_FPExt(Op: m_Value(V&: X)))) &&
2348 X->getType() == Ty) {
2349 // fptrunc (select Cond, Y, (fpext X) --> select Cond, (fptrunc Y), X
2350 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2351 Value *Sel =
2352 Builder.CreateSelectFMF(C: Cond, True: NarrowY, False: X, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2353 return replaceInstUsesWith(I&: FPT, V: Sel);
2354 }
2355 }
2356
2357 if (auto *II = dyn_cast<IntrinsicInst>(Val: FPT.getOperand(i_nocapture: 0))) {
2358 switch (II->getIntrinsicID()) {
2359 default: break;
2360 case Intrinsic::ceil:
2361 case Intrinsic::fabs:
2362 case Intrinsic::floor:
2363 case Intrinsic::nearbyint:
2364 case Intrinsic::rint:
2365 case Intrinsic::round:
2366 case Intrinsic::roundeven:
2367 case Intrinsic::trunc: {
2368 Value *Src = II->getArgOperand(i: 0);
2369 if (!Src->hasOneUse())
2370 break;
2371
2372 // Except for fabs, this transformation requires the input of the unary FP
2373 // operation to be itself an fpext from the type to which we're
2374 // truncating.
2375 if (II->getIntrinsicID() != Intrinsic::fabs) {
2376 FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Val: Src);
2377 if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
2378 break;
2379 }
2380
2381 // Do unary FP operation on smaller type.
2382 // (fptrunc (fabs x)) -> (fabs (fptrunc x))
2383 Value *InnerTrunc = Builder.CreateFPTrunc(V: Src, DestTy: Ty);
2384 Function *Overload = Intrinsic::getOrInsertDeclaration(
2385 M: FPT.getModule(), id: II->getIntrinsicID(), OverloadTys: Ty);
2386 SmallVector<OperandBundleDef, 1> OpBundles;
2387 II->getOperandBundlesAsDefs(Defs&: OpBundles);
2388 CallInst *NewCI =
2389 CallInst::Create(Func: Overload, Args: {InnerTrunc}, Bundles: OpBundles, NameStr: II->getName());
2390 // A normal value may be converted to an infinity. It means that we cannot
2391 // propagate ninf from the intrinsic. So we propagate FMF from fptrunc.
2392 NewCI->copyFastMathFlags(I: &FPT);
2393 return NewCI;
2394 }
2395 }
2396 }
2397
2398 if (Instruction *I = shrinkInsertElt(Trunc&: FPT, Builder))
2399 return I;
2400
2401 Value *Src = FPT.getOperand(i_nocapture: 0);
2402 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2403 auto *FPCast = cast<CastInst>(Val: Src);
2404 if (isKnownExactCastIntToFP(I&: *FPCast))
2405 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2406 }
2407
2408 return nullptr;
2409}
2410
2411Instruction *InstCombinerImpl::visitFPExt(CastInst &FPExt) {
2412 // If the source operand is a cast from integer to FP and known exact, then
2413 // cast the integer operand directly to the destination type.
2414 Type *Ty = FPExt.getType();
2415 Value *Src = FPExt.getOperand(i_nocapture: 0);
2416 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2417 auto *FPCast = cast<CastInst>(Val: Src);
2418 if (isKnownExactCastIntToFP(I&: *FPCast))
2419 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2420 }
2421
2422 return commonCastTransforms(CI&: FPExt);
2423}
2424
2425/// fpto{s/u}i[.sat]({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
2426/// This is safe if the intermediate type has enough bits in its mantissa to
2427/// accurately represent all values of X. For example, this won't work with
2428/// i64 -> float -> i64.
2429template <typename FPToIntTy>
2430Instruction *InstCombinerImpl::foldItoFPtoI(FPToIntTy &FI) {
2431 constexpr bool IsSaturating = std::is_same_v<FPToIntTy, IntrinsicInst>;
2432
2433 if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
2434 return nullptr;
2435
2436 auto *OpI = cast<CastInst>(FI.getOperand(0));
2437 Value *X = OpI->getOperand(0);
2438 Type *XType = X->getType();
2439 Type *DestType = FI.getType();
2440 bool IsInputSigned = isa<SIToFPInst>(OpI);
2441
2442 bool IsOutputSigned;
2443 if constexpr (IsSaturating)
2444 IsOutputSigned = FI.getIntrinsicID() == Intrinsic::fptosi_sat;
2445 else
2446 IsOutputSigned = isa<FPToSIInst>(FI);
2447
2448 // Since we can assume the conversion won't overflow, our decision as to
2449 // whether the input will fit in the float should depend on the minimum
2450 // of the input range and output range.
2451
2452 // This means this is also safe for a signed input and unsigned output, since
2453 // a negative input would lead to undefined behavior.
2454 if (!isKnownExactCastIntToFP(I&: *OpI)) {
2455 if constexpr (!IsSaturating) {
2456 // The first cast may not round exactly based on the source integer width
2457 // and FP width, but the overflow UB rules can still allow this to fold.
2458 // If the destination type is narrow, that means the intermediate FP value
2459 // must be large enough to hold the source value exactly.
2460 //
2461 // For example, (uint8_t)((float)(uint32_t 16777217) is UB.
2462 int OutputSize = (int)DestType->getScalarSizeInBits();
2463 if (OutputSize > OpI->getType()->getFPMantissaWidth())
2464 return nullptr;
2465 } else {
2466 // Sat intrinsics produce a defined saturated value on overflow, so
2467 // the UB-based shortcut is invalid. Require exactness.
2468 return nullptr;
2469 }
2470 }
2471
2472 unsigned SrcWidth = XType->getScalarSizeInBits();
2473 unsigned DestWidth = DestType->getScalarSizeInBits();
2474
2475 if constexpr (IsSaturating) {
2476 // TODO: cross-sign and narrowing cases could be handled with range
2477 // analysis to prove the source fits in the destination.
2478 if (IsInputSigned != IsOutputSigned || DestWidth < SrcWidth)
2479 return nullptr;
2480 }
2481
2482 if (DestWidth > SrcWidth) {
2483 if (IsInputSigned && IsOutputSigned)
2484 return new SExtInst(X, DestType);
2485 return new ZExtInst(X, DestType);
2486 }
2487 if (DestWidth < SrcWidth)
2488 return new TruncInst(X, DestType);
2489
2490 assert(XType == DestType && "Unexpected types for int to FP to int casts");
2491 return replaceInstUsesWith(I&: FI, V: X);
2492}
2493
2494template Instruction *InstCombinerImpl::foldItoFPtoI<CastInst>(CastInst &);
2495template Instruction *
2496InstCombinerImpl::foldItoFPtoI<IntrinsicInst>(IntrinsicInst &);
2497
2498static Instruction *foldFPtoI(Instruction &FI, InstCombiner &IC) {
2499 // fpto{u/s}i non-norm --> 0
2500 FPClassTest Mask =
2501 FI.getOpcode() == Instruction::FPToUI ? fcPosNormal : fcNormal;
2502 KnownFPClass FPClass = computeKnownFPClass(
2503 V: FI.getOperand(i: 0), InterestedClasses: Mask, SQ: IC.getSimplifyQuery().getWithInstruction(I: &FI));
2504 if (FPClass.isKnownNever(Mask))
2505 return IC.replaceInstUsesWith(I&: FI, V: ConstantInt::getNullValue(Ty: FI.getType()));
2506
2507 return nullptr;
2508}
2509
2510Instruction *InstCombinerImpl::visitFPToUI(FPToUIInst &FI) {
2511 if (Instruction *I = foldItoFPtoI(FI))
2512 return I;
2513
2514 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2515 return I;
2516
2517 return commonCastTransforms(CI&: FI);
2518}
2519
2520Instruction *InstCombinerImpl::visitFPToSI(FPToSIInst &FI) {
2521 if (Instruction *I = foldItoFPtoI(FI))
2522 return I;
2523
2524 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2525 return I;
2526
2527 return commonCastTransforms(CI&: FI);
2528}
2529
2530Instruction *InstCombinerImpl::visitUIToFP(CastInst &CI) {
2531 if (Instruction *R = commonCastTransforms(CI))
2532 return R;
2533 if (!CI.hasNonNeg() && isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2534 CI.setNonNeg();
2535 return &CI;
2536 }
2537 return nullptr;
2538}
2539
2540Instruction *InstCombinerImpl::visitSIToFP(CastInst &CI) {
2541 if (Instruction *R = commonCastTransforms(CI))
2542 return R;
2543 if (isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2544 auto *UI =
2545 CastInst::Create(Instruction::UIToFP, S: CI.getOperand(i_nocapture: 0), Ty: CI.getType());
2546 UI->setNonNeg(true);
2547 return UI;
2548 }
2549 return nullptr;
2550}
2551
2552Instruction *InstCombinerImpl::visitIntToPtr(IntToPtrInst &CI) {
2553 // If the source integer type is not the intptr_t type for this target, do a
2554 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
2555 // cast to be exposed to other transforms.
2556 unsigned AS = CI.getAddressSpace();
2557 if (CI.getOperand(i_nocapture: 0)->getType()->getScalarSizeInBits() !=
2558 DL.getPointerSizeInBits(AS)) {
2559 Type *Ty = CI.getOperand(i_nocapture: 0)->getType()->getWithNewType(
2560 EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2561 Value *P = Builder.CreateZExtOrTrunc(V: CI.getOperand(i_nocapture: 0), DestTy: Ty);
2562 return new IntToPtrInst(P, CI.getType());
2563 }
2564
2565 // Replace (inttoptr (add (ptrtoint %Base), %Offset)) with
2566 // (getelementptr i8, %Base, %Offset) if the pointer is only used as integer
2567 // value.
2568 Value *Base;
2569 Value *Offset;
2570 auto UsesPointerAsInt = [](User *U) {
2571 if (isa<ICmpInst, PtrToIntInst>(Val: U))
2572 return true;
2573 if (auto *P = dyn_cast<PHINode>(Val: U))
2574 return P->hasOneUse() && isa<ICmpInst, PtrToIntInst>(Val: *P->user_begin());
2575 return false;
2576 };
2577 if (match(V: CI.getOperand(i_nocapture: 0),
2578 P: m_OneUse(SubPattern: m_c_Add(L: m_PtrToIntSameSize(DL, Op: m_Value(V&: Base)),
2579 R: m_Value(V&: Offset)))) &&
2580 CI.getType()->getPointerAddressSpace() ==
2581 Base->getType()->getPointerAddressSpace() &&
2582 all_of(Range: CI.users(), P: UsesPointerAsInt)) {
2583 return GetElementPtrInst::Create(PointeeType: Builder.getInt8Ty(), Ptr: Base, IdxList: Offset);
2584 }
2585
2586 if (Instruction *I = commonCastTransforms(CI))
2587 return I;
2588
2589 return nullptr;
2590}
2591
2592Value *InstCombinerImpl::foldPtrToIntOrAddrOfGEP(Type *IntTy, Value *Ptr) {
2593 // Look through chain of one-use GEPs.
2594 Type *PtrTy = Ptr->getType();
2595 SmallVector<GEPOperator *> GEPs;
2596 while (true) {
2597 auto *GEP = dyn_cast<GEPOperator>(Val: Ptr);
2598 if (!GEP || !GEP->hasOneUse())
2599 break;
2600 GEPs.push_back(Elt: GEP);
2601 Ptr = GEP->getPointerOperand();
2602 }
2603
2604 // Don't handle case where GEP converts from pointer to vector.
2605 if (GEPs.empty() || PtrTy != Ptr->getType())
2606 return nullptr;
2607
2608 // Check whether we know the integer value of the base pointer.
2609 Value *Res;
2610 Type *IdxTy = DL.getIndexType(PtrTy);
2611 if (match(V: Ptr, P: m_OneUse(SubPattern: m_IntToPtr(Op: m_Value(V&: Res)))) &&
2612 Res->getType() == IntTy && IntTy == IdxTy) {
2613 // pass
2614 } else if (isa<ConstantPointerNull>(Val: Ptr)) {
2615 Res = Constant::getNullValue(Ty: IdxTy);
2616 } else {
2617 return nullptr;
2618 }
2619
2620 // Perform the entire operation on integers instead.
2621 for (GEPOperator *GEP : reverse(C&: GEPs)) {
2622 Value *Offset = EmitGEPOffset(GEP);
2623 Res = Builder.CreateAdd(LHS: Res, RHS: Offset, Name: "", HasNUW: GEP->hasNoUnsignedWrap());
2624 }
2625 return Builder.CreateZExtOrTrunc(V: Res, DestTy: IntTy);
2626}
2627
2628Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
2629 // If the destination integer type is not the intptr_t type for this target,
2630 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
2631 // to be exposed to other transforms.
2632 Value *SrcOp = CI.getPointerOperand();
2633 Type *SrcTy = SrcOp->getType();
2634 Type *Ty = CI.getType();
2635 unsigned AS = CI.getPointerAddressSpace();
2636 unsigned TySize = Ty->getScalarSizeInBits();
2637 unsigned PtrSize = DL.getPointerSizeInBits(AS);
2638 if (TySize != PtrSize) {
2639 Type *IntPtrTy =
2640 SrcTy->getWithNewType(EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2641 Value *P = Builder.CreatePtrToInt(V: SrcOp, DestTy: IntPtrTy);
2642 return CastInst::CreateIntegerCast(S: P, Ty, /*isSigned=*/false);
2643 }
2644
2645 // (ptrtoint (ptrmask P, M))
2646 // -> (and (ptrtoint P), M)
2647 // This is generally beneficial as `and` is better supported than `ptrmask`.
2648 Value *Ptr, *Mask;
2649 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(Op0: m_Value(V&: Ptr),
2650 Op1: m_Value(V&: Mask)))) &&
2651 Mask->getType() == Ty)
2652 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToInt(V: Ptr, DestTy: Ty), V2: Mask);
2653
2654 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2655 return replaceInstUsesWith(I&: CI, V);
2656
2657 Value *Vec, *Scalar, *Index;
2658 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_InsertElt(Val: m_IntToPtr(Op: m_Value(V&: Vec)),
2659 Elt: m_Value(V&: Scalar), Idx: m_Value(V&: Index)))) &&
2660 Vec->getType() == Ty) {
2661 assert(Vec->getType()->getScalarSizeInBits() == PtrSize && "Wrong type");
2662 // Convert the scalar to int followed by insert to eliminate one cast:
2663 // p2i (ins (i2p Vec), Scalar, Index --> ins Vec, (p2i Scalar), Index
2664 Value *NewCast = Builder.CreatePtrToInt(V: Scalar, DestTy: Ty->getScalarType());
2665 return InsertElementInst::Create(Vec, NewElt: NewCast, Idx: Index);
2666 }
2667
2668 return commonCastTransforms(CI);
2669}
2670
2671Instruction *InstCombinerImpl::visitPtrToAddr(PtrToAddrInst &CI) {
2672 Value *SrcOp = CI.getPointerOperand();
2673 Type *Ty = CI.getType();
2674
2675 // (ptrtoaddr (ptrmask P, M))
2676 // -> (and (ptrtoaddr P), M)
2677 // This is generally beneficial as `and` is better supported than `ptrmask`.
2678 Value *Ptr, *Mask;
2679 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(Op0: m_Value(V&: Ptr),
2680 Op1: m_Value(V&: Mask)))) &&
2681 Mask->getType() == Ty)
2682 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToAddr(V: Ptr), V2: Mask);
2683
2684 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2685 return replaceInstUsesWith(I&: CI, V);
2686
2687 // FIXME: Implement variants of ptrtoint folds.
2688 return commonCastTransforms(CI);
2689}
2690
2691/// This input value (which is known to have vector type) is being zero extended
2692/// or truncated to the specified vector type. Since the zext/trunc is done
2693/// using an integer type, we have a (bitcast(cast(bitcast))) pattern,
2694/// endianness will impact which end of the vector that is extended or
2695/// truncated.
2696///
2697/// A vector is always stored with index 0 at the lowest address, which
2698/// corresponds to the most significant bits for a big endian stored integer and
2699/// the least significant bits for little endian. A trunc/zext of an integer
2700/// impacts the big end of the integer. Thus, we need to add/remove elements at
2701/// the front of the vector for big endian targets, and the back of the vector
2702/// for little endian targets.
2703///
2704/// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
2705///
2706/// The source and destination vector types may have different element types.
2707static Instruction *
2708optimizeVectorResizeWithIntegerBitCasts(Value *InVal, VectorType *DestTy,
2709 InstCombinerImpl &IC) {
2710 // We can only do this optimization if the output is a multiple of the input
2711 // element size, or the input is a multiple of the output element size.
2712 // Convert the input type to have the same element type as the output.
2713 VectorType *SrcTy = cast<VectorType>(Val: InVal->getType());
2714
2715 if (SrcTy->getElementType() != DestTy->getElementType()) {
2716 // The input types don't need to be identical, but for now they must be the
2717 // same size. There is no specific reason we couldn't handle things like
2718 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
2719 // there yet.
2720 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
2721 DestTy->getElementType()->getPrimitiveSizeInBits())
2722 return nullptr;
2723
2724 SrcTy =
2725 FixedVectorType::get(ElementType: DestTy->getElementType(),
2726 NumElts: cast<FixedVectorType>(Val: SrcTy)->getNumElements());
2727 InVal = IC.Builder.CreateBitCast(V: InVal, DestTy: SrcTy);
2728 }
2729
2730 bool IsBigEndian = IC.getDataLayout().isBigEndian();
2731 unsigned SrcElts = cast<FixedVectorType>(Val: SrcTy)->getNumElements();
2732 unsigned DestElts = cast<FixedVectorType>(Val: DestTy)->getNumElements();
2733
2734 assert(SrcElts != DestElts && "Element counts should be different.");
2735
2736 // Now that the element types match, get the shuffle mask and RHS of the
2737 // shuffle to use, which depends on whether we're increasing or decreasing the
2738 // size of the input.
2739 auto ShuffleMaskStorage = llvm::to_vector<16>(Range: llvm::seq<int>(Begin: 0, End: SrcElts));
2740 ArrayRef<int> ShuffleMask;
2741 Value *V2;
2742
2743 if (SrcElts > DestElts) {
2744 // If we're shrinking the number of elements (rewriting an integer
2745 // truncate), just shuffle in the elements corresponding to the least
2746 // significant bits from the input and use poison as the second shuffle
2747 // input.
2748 V2 = PoisonValue::get(T: SrcTy);
2749 // Make sure the shuffle mask selects the "least significant bits" by
2750 // keeping elements from back of the src vector for big endian, and from the
2751 // front for little endian.
2752 ShuffleMask = ShuffleMaskStorage;
2753 if (IsBigEndian)
2754 ShuffleMask = ShuffleMask.take_back(N: DestElts);
2755 else
2756 ShuffleMask = ShuffleMask.take_front(N: DestElts);
2757 } else {
2758 // If we're increasing the number of elements (rewriting an integer zext),
2759 // shuffle in all of the elements from InVal. Fill the rest of the result
2760 // elements with zeros from a constant zero.
2761 V2 = Constant::getNullValue(Ty: SrcTy);
2762 // Use first elt from V2 when indicating zero in the shuffle mask.
2763 uint32_t NullElt = SrcElts;
2764 // Extend with null values in the "most significant bits" by adding elements
2765 // in front of the src vector for big endian, and at the back for little
2766 // endian.
2767 unsigned DeltaElts = DestElts - SrcElts;
2768 if (IsBigEndian)
2769 ShuffleMaskStorage.insert(I: ShuffleMaskStorage.begin(), NumToInsert: DeltaElts, Elt: NullElt);
2770 else
2771 ShuffleMaskStorage.append(NumInputs: DeltaElts, Elt: NullElt);
2772 ShuffleMask = ShuffleMaskStorage;
2773 }
2774
2775 return new ShuffleVectorInst(InVal, V2, ShuffleMask);
2776}
2777
2778static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
2779 return Value % Ty->getPrimitiveSizeInBits() == 0;
2780}
2781
2782static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
2783 return Value / Ty->getPrimitiveSizeInBits();
2784}
2785
2786/// V is a value which is inserted into a vector of VecEltTy.
2787/// Look through the value to see if we can decompose it into
2788/// insertions into the vector. See the example in the comment for
2789/// OptimizeIntegerToVectorInsertions for the pattern this handles.
2790/// The type of V is always a non-zero multiple of VecEltTy's size.
2791/// Shift is the number of bits between the lsb of V and the lsb of
2792/// the vector.
2793///
2794/// This returns false if the pattern can't be matched or true if it can,
2795/// filling in Elements with the elements found here.
2796static bool collectInsertionElements(Value *V, unsigned Shift,
2797 SmallVectorImpl<Value *> &Elements,
2798 Type *VecEltTy, bool isBigEndian) {
2799 assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
2800 "Shift should be a multiple of the element type size");
2801
2802 // Poison values never contribute useful bits to the result.
2803 if (match(V, P: m_Poison()))
2804 return true;
2805
2806 // If we got down to a value of the right type, we win, try inserting into the
2807 // right element.
2808 if (V->getType() == VecEltTy) {
2809 // Inserting null doesn't actually insert any elements.
2810 if (Constant *C = dyn_cast<Constant>(Val: V))
2811 if (C->isNullValue())
2812 return true;
2813
2814 unsigned ElementIndex = getTypeSizeIndex(Value: Shift, Ty: VecEltTy);
2815 if (isBigEndian)
2816 ElementIndex = Elements.size() - ElementIndex - 1;
2817
2818 // Fail if multiple elements are inserted into this slot.
2819 if (Elements[ElementIndex])
2820 return false;
2821
2822 Elements[ElementIndex] = V;
2823 return true;
2824 }
2825
2826 if (Constant *C = dyn_cast<Constant>(Val: V)) {
2827 // Figure out the # elements this provides, and bitcast it or slice it up
2828 // as required.
2829 unsigned NumElts = getTypeSizeIndex(Value: C->getType()->getPrimitiveSizeInBits(),
2830 Ty: VecEltTy);
2831 // If the constant is the size of a vector element, we just need to bitcast
2832 // it to the right type so it gets properly inserted.
2833 if (NumElts == 1)
2834 return collectInsertionElements(V: ConstantExpr::getBitCast(C, Ty: VecEltTy),
2835 Shift, Elements, VecEltTy, isBigEndian);
2836
2837 // Okay, this is a constant that covers multiple elements. Slice it up into
2838 // pieces and insert each element-sized piece into the vector.
2839 if (!isa<IntegerType>(Val: C->getType()))
2840 C = ConstantExpr::getBitCast(C, Ty: IntegerType::get(C&: V->getContext(),
2841 NumBits: C->getType()->getPrimitiveSizeInBits()));
2842 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
2843 Type *ElementIntTy = IntegerType::get(C&: C->getContext(), NumBits: ElementSize);
2844
2845 for (unsigned i = 0; i != NumElts; ++i) {
2846 unsigned ShiftI = i * ElementSize;
2847 Constant *Piece = ConstantFoldBinaryInstruction(
2848 Opcode: Instruction::LShr, V1: C, V2: ConstantInt::get(Ty: C->getType(), V: ShiftI));
2849 if (!Piece)
2850 return false;
2851
2852 Piece = ConstantExpr::getTrunc(C: Piece, Ty: ElementIntTy);
2853 if (!collectInsertionElements(V: Piece, Shift: ShiftI + Shift, Elements, VecEltTy,
2854 isBigEndian))
2855 return false;
2856 }
2857 return true;
2858 }
2859
2860 if (!V->hasOneUse()) return false;
2861
2862 Instruction *I = dyn_cast<Instruction>(Val: V);
2863 if (!I) return false;
2864 switch (I->getOpcode()) {
2865 default: return false; // Unhandled case.
2866 case Instruction::BitCast:
2867 if (I->getOperand(i: 0)->getType()->isVectorTy())
2868 return false;
2869 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2870 isBigEndian);
2871 case Instruction::ZExt:
2872 if (!isMultipleOfTypeSize(
2873 Value: I->getOperand(i: 0)->getType()->getPrimitiveSizeInBits(),
2874 Ty: VecEltTy))
2875 return false;
2876 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2877 isBigEndian);
2878 case Instruction::Or:
2879 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2880 isBigEndian) &&
2881 collectInsertionElements(V: I->getOperand(i: 1), Shift, Elements, VecEltTy,
2882 isBigEndian);
2883 case Instruction::Shl: {
2884 // Must be shifting by a constant that is a multiple of the element size.
2885 ConstantInt *CI = dyn_cast<ConstantInt>(Val: I->getOperand(i: 1));
2886 if (!CI) return false;
2887 Shift += CI->getZExtValue();
2888 if (!isMultipleOfTypeSize(Value: Shift, Ty: VecEltTy)) return false;
2889 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
2890 isBigEndian);
2891 }
2892
2893 }
2894}
2895
2896
2897/// If the input is an 'or' instruction, we may be doing shifts and ors to
2898/// assemble the elements of the vector manually.
2899/// Try to rip the code out and replace it with insertelements. This is to
2900/// optimize code like this:
2901///
2902/// %tmp37 = bitcast float %inc to i32
2903/// %tmp38 = zext i32 %tmp37 to i64
2904/// %tmp31 = bitcast float %inc5 to i32
2905/// %tmp32 = zext i32 %tmp31 to i64
2906/// %tmp33 = shl i64 %tmp32, 32
2907/// %ins35 = or i64 %tmp33, %tmp38
2908/// %tmp43 = bitcast i64 %ins35 to <2 x float>
2909///
2910/// Into two insertelements that do "buildvector{%inc, %inc5}".
2911static Value *optimizeIntegerToVectorInsertions(BitCastInst &CI,
2912 InstCombinerImpl &IC) {
2913 auto *DestVecTy = cast<FixedVectorType>(Val: CI.getType());
2914 Value *IntInput = CI.getOperand(i_nocapture: 0);
2915
2916 // if the int input is just an undef value do not try to optimize to vector
2917 // insertions as it will prevent undef propagation
2918 if (isa<UndefValue>(Val: IntInput))
2919 return nullptr;
2920
2921 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
2922 if (!collectInsertionElements(V: IntInput, Shift: 0, Elements,
2923 VecEltTy: DestVecTy->getElementType(),
2924 isBigEndian: IC.getDataLayout().isBigEndian()))
2925 return nullptr;
2926
2927 // If we succeeded, we know that all of the element are specified by Elements
2928 // or are zero if Elements has a null entry. Recast this as a set of
2929 // insertions.
2930 Value *Result = Constant::getNullValue(Ty: CI.getType());
2931 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
2932 if (!Elements[i]) continue; // Unset element.
2933
2934 Result = IC.Builder.CreateInsertElement(Vec: Result, NewElt: Elements[i],
2935 Idx: IC.Builder.getInt32(C: i));
2936 }
2937
2938 return Result;
2939}
2940
2941/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
2942/// vector followed by extract element. The backend tends to handle bitcasts of
2943/// vectors better than bitcasts of scalars because vector registers are
2944/// usually not type-specific like scalar integer or scalar floating-point.
2945static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast,
2946 InstCombinerImpl &IC) {
2947 Value *VecOp, *Index;
2948 if (!match(V: BitCast.getOperand(i_nocapture: 0),
2949 P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_Value(V&: Index)))))
2950 return nullptr;
2951
2952 // The bitcast must be to a vectorizable type, otherwise we can't make a new
2953 // type to extract from.
2954 Type *DestType = BitCast.getType();
2955 VectorType *VecType = cast<VectorType>(Val: VecOp->getType());
2956 if (VectorType::isValidElementType(ElemTy: DestType)) {
2957 auto *NewVecType = VectorType::get(ElementType: DestType, Other: VecType);
2958 auto *NewBC = IC.Builder.CreateBitCast(V: VecOp, DestTy: NewVecType, Name: "bc");
2959 return ExtractElementInst::Create(Vec: NewBC, Idx: Index);
2960 }
2961
2962 // Only solve DestType is vector to avoid inverse transform in visitBitCast.
2963 // bitcast (extractelement <1 x elt>, dest) -> bitcast(<1 x elt>, dest)
2964 auto *FixedVType = dyn_cast<FixedVectorType>(Val: VecType);
2965 if (DestType->isVectorTy() && FixedVType && FixedVType->getNumElements() == 1)
2966 return CastInst::Create(Instruction::BitCast, S: VecOp, Ty: DestType);
2967
2968 return nullptr;
2969}
2970
2971/// Change the type of a bitwise logic operation if we can eliminate a bitcast.
2972static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast,
2973 InstCombiner::BuilderTy &Builder) {
2974 Type *DestTy = BitCast.getType();
2975 BinaryOperator *BO;
2976
2977 if (!match(V: BitCast.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BO))) ||
2978 !BO->isBitwiseLogicOp())
2979 return nullptr;
2980
2981 // FIXME: This transform is restricted to vector types to avoid backend
2982 // problems caused by creating potentially illegal operations. If a fix-up is
2983 // added to handle that situation, we can remove this check.
2984 if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
2985 return nullptr;
2986
2987 if (DestTy->isFPOrFPVectorTy()) {
2988 Value *X, *Y;
2989 // bitcast(logic(bitcast(X), bitcast(Y))) -> bitcast'(logic(bitcast'(X), Y))
2990 if (match(V: BO->getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
2991 match(V: BO->getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: Y))))) {
2992 if (X->getType()->isFPOrFPVectorTy() &&
2993 Y->getType()->isIntOrIntVectorTy()) {
2994 Value *CastedOp =
2995 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy: Y->getType());
2996 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: Y);
2997 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
2998 }
2999 if (X->getType()->isIntOrIntVectorTy() &&
3000 Y->getType()->isFPOrFPVectorTy()) {
3001 Value *CastedOp =
3002 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy: X->getType());
3003 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: X);
3004 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
3005 }
3006 }
3007 return nullptr;
3008 }
3009
3010 if (!DestTy->isIntOrIntVectorTy())
3011 return nullptr;
3012
3013 Value *X;
3014 if (match(V: BO->getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
3015 X->getType() == DestTy && !isa<Constant>(Val: X)) {
3016 // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
3017 Value *CastedOp1 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy);
3018 return BinaryOperator::Create(Op: BO->getOpcode(), S1: X, S2: CastedOp1);
3019 }
3020
3021 if (match(V: BO->getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
3022 X->getType() == DestTy && !isa<Constant>(Val: X)) {
3023 // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
3024 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
3025 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: X);
3026 }
3027
3028 // Canonicalize vector bitcasts to come before vector bitwise logic with a
3029 // constant. This eases recognition of special constants for later ops.
3030 // Example:
3031 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
3032 Constant *C;
3033 if (match(V: BO->getOperand(i_nocapture: 1), P: m_Constant(C))) {
3034 // bitcast (logic X, C) --> logic (bitcast X, C')
3035 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
3036 Value *CastedC = Builder.CreateBitCast(V: C, DestTy);
3037 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: CastedC);
3038 }
3039
3040 return nullptr;
3041}
3042
3043/// Change the type of a select if we can eliminate a bitcast.
3044static Instruction *foldBitCastSelect(BitCastInst &BitCast,
3045 InstCombiner::BuilderTy &Builder) {
3046 Value *Cond, *TVal, *FVal;
3047 if (!match(V: BitCast.getOperand(i_nocapture: 0),
3048 P: m_OneUse(SubPattern: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: TVal), R: m_Value(V&: FVal)))))
3049 return nullptr;
3050
3051 // A vector select must maintain the same number of elements in its operands.
3052 Type *CondTy = Cond->getType();
3053 Type *DestTy = BitCast.getType();
3054
3055 auto *DestVecTy = dyn_cast<VectorType>(Val: DestTy);
3056
3057 if (auto *CondVTy = dyn_cast<VectorType>(Val: CondTy))
3058 if (!DestVecTy ||
3059 CondVTy->getElementCount() != DestVecTy->getElementCount())
3060 return nullptr;
3061
3062 auto *Sel = cast<Instruction>(Val: BitCast.getOperand(i_nocapture: 0));
3063 auto *SrcVecTy = dyn_cast<VectorType>(Val: TVal->getType());
3064
3065 if ((isa<Constant>(Val: TVal) || isa<Constant>(Val: FVal)) &&
3066 (!DestVecTy ||
3067 (SrcVecTy && ElementCount::isKnownLE(LHS: DestVecTy->getElementCount(),
3068 RHS: SrcVecTy->getElementCount())))) {
3069 // Avoid introducing select of vector (or select of vector with more
3070 // elements) until the backend can undo this transformation.
3071 Value *CastedTVal = Builder.CreateBitCast(V: TVal, DestTy);
3072 Value *CastedFVal = Builder.CreateBitCast(V: FVal, DestTy);
3073 return SelectInst::Create(C: Cond, S1: CastedTVal, S2: CastedFVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3074 }
3075
3076 // FIXME: This transform is restricted from changing the select between
3077 // scalars and vectors to avoid backend problems caused by creating
3078 // potentially illegal operations. If a fix-up is added to handle that
3079 // situation, we can remove this check.
3080 if ((DestVecTy != nullptr) != (SrcVecTy != nullptr))
3081 return nullptr;
3082
3083 Value *X;
3084 if (match(V: TVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) && X->getType() == DestTy &&
3085 !isa<Constant>(Val: X)) {
3086 // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
3087 Value *CastedVal = Builder.CreateBitCast(V: FVal, DestTy);
3088 return SelectInst::Create(C: Cond, S1: X, S2: CastedVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3089 }
3090
3091 if (match(V: FVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) && X->getType() == DestTy &&
3092 !isa<Constant>(Val: X)) {
3093 // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
3094 Value *CastedVal = Builder.CreateBitCast(V: TVal, DestTy);
3095 return SelectInst::Create(C: Cond, S1: CastedVal, S2: X, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3096 }
3097
3098 return nullptr;
3099}
3100
3101/// Check if all users of CI are StoreInsts.
3102static bool hasStoreUsersOnly(CastInst &CI) {
3103 for (User *U : CI.users()) {
3104 if (!isa<StoreInst>(Val: U))
3105 return false;
3106 }
3107 return true;
3108}
3109
3110/// This function handles following case
3111///
3112/// A -> B cast
3113/// PHI
3114/// B -> A cast
3115///
3116/// All the related PHI nodes can be replaced by new PHI nodes with type A.
3117/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
3118Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
3119 PHINode *PN) {
3120 // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
3121 if (hasStoreUsersOnly(CI))
3122 return nullptr;
3123
3124 Value *Src = CI.getOperand(i_nocapture: 0);
3125 Type *SrcTy = Src->getType(); // Type B
3126 Type *DestTy = CI.getType(); // Type A
3127
3128 SmallVector<PHINode *, 4> PhiWorklist;
3129 SmallSetVector<PHINode *, 4> OldPhiNodes;
3130
3131 // Find all of the A->B casts and PHI nodes.
3132 // We need to inspect all related PHI nodes, but PHIs can be cyclic, so
3133 // OldPhiNodes is used to track all known PHI nodes, before adding a new
3134 // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
3135 PhiWorklist.push_back(Elt: PN);
3136 OldPhiNodes.insert(X: PN);
3137 while (!PhiWorklist.empty()) {
3138 auto *OldPN = PhiWorklist.pop_back_val();
3139 for (Value *IncValue : OldPN->incoming_values()) {
3140 if (isa<Constant>(Val: IncValue))
3141 continue;
3142
3143 if (auto *LI = dyn_cast<LoadInst>(Val: IncValue)) {
3144 // If there is a sequence of one or more load instructions, each loaded
3145 // value is used as address of later load instruction, bitcast is
3146 // necessary to change the value type, don't optimize it. For
3147 // simplicity we give up if the load address comes from another load.
3148 Value *Addr = LI->getOperand(i_nocapture: 0);
3149 if (Addr == &CI || isa<LoadInst>(Val: Addr))
3150 return nullptr;
3151 // Don't tranform "load <256 x i32>, <256 x i32>*" to
3152 // "load x86_amx, x86_amx*", because x86_amx* is invalid.
3153 // TODO: Remove this check when bitcast between vector and x86_amx
3154 // is replaced with a specific intrinsic.
3155 if (DestTy->isX86_AMXTy())
3156 return nullptr;
3157 if (LI->hasOneUse() && LI->isSimple())
3158 continue;
3159 // If a LoadInst has more than one use, changing the type of loaded
3160 // value may create another bitcast.
3161 return nullptr;
3162 }
3163
3164 if (auto *PNode = dyn_cast<PHINode>(Val: IncValue)) {
3165 if (OldPhiNodes.insert(X: PNode))
3166 PhiWorklist.push_back(Elt: PNode);
3167 continue;
3168 }
3169
3170 auto *BCI = dyn_cast<BitCastInst>(Val: IncValue);
3171 // We can't handle other instructions.
3172 if (!BCI)
3173 return nullptr;
3174
3175 // Verify it's a A->B cast.
3176 Type *TyA = BCI->getOperand(i_nocapture: 0)->getType();
3177 Type *TyB = BCI->getType();
3178 if (TyA != DestTy || TyB != SrcTy)
3179 return nullptr;
3180 }
3181 }
3182
3183 // Check that each user of each old PHI node is something that we can
3184 // rewrite, so that all of the old PHI nodes can be cleaned up afterwards.
3185 for (auto *OldPN : OldPhiNodes) {
3186 for (User *V : OldPN->users()) {
3187 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3188 if (!SI->isSimple() || SI->getOperand(i_nocapture: 0) != OldPN)
3189 return nullptr;
3190 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3191 // Verify it's a B->A cast.
3192 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3193 Type *TyA = BCI->getType();
3194 if (TyA != DestTy || TyB != SrcTy)
3195 return nullptr;
3196 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3197 // As long as the user is another old PHI node, then even if we don't
3198 // rewrite it, the PHI web we're considering won't have any users
3199 // outside itself, so it'll be dead.
3200 if (!OldPhiNodes.contains(key: PHI))
3201 return nullptr;
3202 } else {
3203 return nullptr;
3204 }
3205 }
3206 }
3207
3208 // For each old PHI node, create a corresponding new PHI node with a type A.
3209 SmallDenseMap<PHINode *, PHINode *> NewPNodes;
3210 for (auto *OldPN : OldPhiNodes) {
3211 Builder.SetInsertPoint(OldPN);
3212 PHINode *NewPN = Builder.CreatePHI(Ty: DestTy, NumReservedValues: OldPN->getNumOperands());
3213 NewPNodes[OldPN] = NewPN;
3214 }
3215
3216 // Fill in the operands of new PHI nodes.
3217 for (auto *OldPN : OldPhiNodes) {
3218 PHINode *NewPN = NewPNodes[OldPN];
3219 for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
3220 Value *V = OldPN->getOperand(i_nocapture: j);
3221 Value *NewV = nullptr;
3222 if (auto *C = dyn_cast<Constant>(Val: V)) {
3223 NewV = ConstantExpr::getBitCast(C, Ty: DestTy);
3224 } else if (auto *LI = dyn_cast<LoadInst>(Val: V)) {
3225 // Explicitly perform load combine to make sure no opposing transform
3226 // can remove the bitcast in the meantime and trigger an infinite loop.
3227 Builder.SetInsertPoint(LI);
3228 NewV = combineLoadToNewType(LI&: *LI, NewTy: DestTy);
3229 // Remove the old load and its use in the old phi, which itself becomes
3230 // dead once the whole transform finishes.
3231 replaceInstUsesWith(I&: *LI, V: PoisonValue::get(T: LI->getType()));
3232 eraseInstFromFunction(I&: *LI);
3233 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3234 NewV = BCI->getOperand(i_nocapture: 0);
3235 } else if (auto *PrevPN = dyn_cast<PHINode>(Val: V)) {
3236 NewV = NewPNodes[PrevPN];
3237 }
3238 assert(NewV);
3239 NewPN->addIncoming(V: NewV, BB: OldPN->getIncomingBlock(i: j));
3240 }
3241 }
3242
3243 // Traverse all accumulated PHI nodes and process its users,
3244 // which are Stores and BitcCasts. Without this processing
3245 // NewPHI nodes could be replicated and could lead to extra
3246 // moves generated after DeSSA.
3247 // If there is a store with type B, change it to type A.
3248
3249
3250 // Replace users of BitCast B->A with NewPHI. These will help
3251 // later to get rid off a closure formed by OldPHI nodes.
3252 Instruction *RetVal = nullptr;
3253 for (auto *OldPN : OldPhiNodes) {
3254 PHINode *NewPN = NewPNodes[OldPN];
3255 for (User *V : make_early_inc_range(Range: OldPN->users())) {
3256 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3257 assert(SI->isSimple() && SI->getOperand(0) == OldPN);
3258 Builder.SetInsertPoint(SI);
3259 auto *NewBC =
3260 cast<BitCastInst>(Val: Builder.CreateBitCast(V: NewPN, DestTy: SrcTy));
3261 SI->setOperand(i_nocapture: 0, Val_nocapture: NewBC);
3262 Worklist.push(I: SI);
3263 assert(hasStoreUsersOnly(*NewBC));
3264 }
3265 else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3266 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3267 Type *TyA = BCI->getType();
3268 assert(TyA == DestTy && TyB == SrcTy);
3269 (void) TyA;
3270 (void) TyB;
3271 Instruction *I = replaceInstUsesWith(I&: *BCI, V: NewPN);
3272 if (BCI == &CI)
3273 RetVal = I;
3274 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3275 assert(OldPhiNodes.contains(PHI));
3276 (void) PHI;
3277 } else {
3278 llvm_unreachable("all uses should be handled");
3279 }
3280 }
3281 }
3282
3283 return RetVal;
3284}
3285
3286/// Fold (bitcast (or (and (bitcast X to int), signmask), nneg Y) to fp) to
3287/// copysign((bitcast Y to fp), X)
3288static Value *foldCopySignIdioms(BitCastInst &CI,
3289 InstCombiner::BuilderTy &Builder,
3290 const SimplifyQuery &SQ) {
3291 Value *X, *Y;
3292 Type *FTy = CI.getType();
3293 if (!FTy->isFPOrFPVectorTy())
3294 return nullptr;
3295 if (!match(V: &CI, P: m_ElementWiseBitCast(Op: m_c_Or(
3296 L: m_And(L: m_ElementWiseBitCast(Op: m_Value(V&: X)), R: m_SignMask()),
3297 R: m_Value(V&: Y)))))
3298 return nullptr;
3299 if (X->getType() != FTy)
3300 return nullptr;
3301 if (!isKnownNonNegative(V: Y, SQ))
3302 return nullptr;
3303
3304 return Builder.CreateCopySign(LHS: Builder.CreateBitCast(V: Y, DestTy: FTy), RHS: X);
3305}
3306
3307Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
3308 // If the operands are integer typed then apply the integer transforms,
3309 // otherwise just apply the common ones.
3310 Value *Src = CI.getOperand(i_nocapture: 0);
3311 Type *SrcTy = Src->getType();
3312 Type *DestTy = CI.getType();
3313
3314 // Get rid of casts from one type to the same type. These are useless and can
3315 // be replaced by the operand.
3316 if (DestTy == Src->getType())
3317 return replaceInstUsesWith(I&: CI, V: Src);
3318
3319 if (isa<FixedVectorType>(Val: DestTy)) {
3320 if (isa<IntegerType>(Val: SrcTy)) {
3321 // If this is a cast from an integer to vector, check to see if the input
3322 // is a trunc or zext of a bitcast from vector. If so, we can replace all
3323 // the casts with a shuffle and (potentially) a bitcast.
3324 if (isa<TruncInst>(Val: Src) || isa<ZExtInst>(Val: Src)) {
3325 CastInst *SrcCast = cast<CastInst>(Val: Src);
3326 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(Val: SrcCast->getOperand(i_nocapture: 0)))
3327 if (isa<VectorType>(Val: BCIn->getOperand(i_nocapture: 0)->getType()))
3328 if (Instruction *I = optimizeVectorResizeWithIntegerBitCasts(
3329 InVal: BCIn->getOperand(i_nocapture: 0), DestTy: cast<VectorType>(Val: DestTy), IC&: *this))
3330 return I;
3331 }
3332
3333 // If the input is an 'or' instruction, we may be doing shifts and ors to
3334 // assemble the elements of the vector manually. Try to rip the code out
3335 // and replace it with insertelements.
3336 if (Value *V = optimizeIntegerToVectorInsertions(CI, IC&: *this))
3337 return replaceInstUsesWith(I&: CI, V);
3338 }
3339 }
3340
3341 if (FixedVectorType *SrcVTy = dyn_cast<FixedVectorType>(Val: SrcTy)) {
3342 if (SrcVTy->getNumElements() == 1) {
3343 // If our destination is not a vector, then make this a straight
3344 // scalar-scalar cast.
3345 if (!DestTy->isVectorTy()) {
3346 Value *Elem =
3347 Builder.CreateExtractElement(Vec: Src,
3348 Idx: Constant::getNullValue(Ty: Type::getInt32Ty(C&: CI.getContext())));
3349 return CastInst::Create(Instruction::BitCast, S: Elem, Ty: DestTy);
3350 }
3351
3352 // Otherwise, see if our source is an insert. If so, then use the scalar
3353 // component directly:
3354 // bitcast (inselt <1 x elt> V, X, 0) to <n x m> --> bitcast X to <n x m>
3355 if (auto *InsElt = dyn_cast<InsertElementInst>(Val: Src))
3356 return new BitCastInst(InsElt->getOperand(i_nocapture: 1), DestTy);
3357 }
3358
3359 // Convert an artificial vector insert into more analyzable bitwise logic.
3360 unsigned BitWidth = DestTy->getScalarSizeInBits();
3361 Value *X, *Y;
3362 uint64_t IndexC;
3363 if (match(V: Src, P: m_OneUse(SubPattern: m_InsertElt(Val: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X))),
3364 Elt: m_Value(V&: Y), Idx: m_ConstantInt(V&: IndexC)))) &&
3365 DestTy->isIntegerTy() && X->getType() == DestTy &&
3366 Y->getType()->isIntegerTy() && isDesirableIntType(BitWidth)) {
3367 // Adjust for big endian - the LSBs are at the high index.
3368 if (DL.isBigEndian())
3369 IndexC = SrcVTy->getNumElements() - 1 - IndexC;
3370
3371 // We only handle (endian-normalized) insert to index 0. Any other insert
3372 // would require a left-shift, so that is an extra instruction.
3373 if (IndexC == 0) {
3374 // bitcast (inselt (bitcast X), Y, 0) --> or (and X, MaskC), (zext Y)
3375 unsigned EltWidth = Y->getType()->getScalarSizeInBits();
3376 APInt MaskC = APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - EltWidth);
3377 Value *AndX = Builder.CreateAnd(LHS: X, RHS: MaskC);
3378 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
3379 return BinaryOperator::CreateOr(V1: AndX, V2: ZextY);
3380 }
3381 }
3382 }
3383
3384 if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Val: Src)) {
3385 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
3386 // a bitcast to a vector with the same # elts.
3387 Value *ShufOp0 = Shuf->getOperand(i_nocapture: 0);
3388 Value *ShufOp1 = Shuf->getOperand(i_nocapture: 1);
3389 auto ShufElts = cast<VectorType>(Val: Shuf->getType())->getElementCount();
3390 auto SrcVecElts = cast<VectorType>(Val: ShufOp0->getType())->getElementCount();
3391 if (Shuf->hasOneUse() && DestTy->isVectorTy() &&
3392 cast<VectorType>(Val: DestTy)->getElementCount() == ShufElts &&
3393 ShufElts == SrcVecElts) {
3394 BitCastInst *Tmp;
3395 // If either of the operands is a cast from CI.getType(), then
3396 // evaluating the shuffle in the casted destination's type will allow
3397 // us to eliminate at least one cast.
3398 if (((Tmp = dyn_cast<BitCastInst>(Val: ShufOp0)) &&
3399 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy) ||
3400 ((Tmp = dyn_cast<BitCastInst>(Val: ShufOp1)) &&
3401 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy)) {
3402 Value *LHS = Builder.CreateBitCast(V: ShufOp0, DestTy);
3403 Value *RHS = Builder.CreateBitCast(V: ShufOp1, DestTy);
3404 // Return a new shuffle vector. Use the same element ID's, as we
3405 // know the vector types match #elts.
3406 return new ShuffleVectorInst(LHS, RHS, Shuf->getShuffleMask());
3407 }
3408 }
3409
3410 // A bitcasted-to-scalar and byte/bit reversing shuffle is better recognized
3411 // as a byte/bit swap:
3412 // bitcast <N x i8> (shuf X, undef, <N, N-1,...0>) -> bswap (bitcast X)
3413 // bitcast <N x i1> (shuf X, undef, <N, N-1,...0>) -> bitreverse (bitcast X)
3414 if (DestTy->isIntegerTy() && ShufElts.getKnownMinValue() % 2 == 0 &&
3415 Shuf->hasOneUse() && Shuf->isReverse() && match(V: ShufOp1, P: m_Poison())) {
3416 unsigned IntrinsicNum = 0;
3417 if (DL.isLegalInteger(Width: DestTy->getScalarSizeInBits()) &&
3418 SrcTy->getScalarSizeInBits() == 8) {
3419 IntrinsicNum = Intrinsic::bswap;
3420 } else if (SrcTy->getScalarSizeInBits() == 1) {
3421 IntrinsicNum = Intrinsic::bitreverse;
3422 }
3423 if (IntrinsicNum != 0) {
3424 assert(ShufOp0->getType() == SrcTy && "Unexpected shuffle mask");
3425 Function *BswapOrBitreverse = Intrinsic::getOrInsertDeclaration(
3426 M: CI.getModule(), id: IntrinsicNum, OverloadTys: DestTy);
3427 Value *ScalarX = Builder.CreateBitCast(V: ShufOp0, DestTy);
3428 return CallInst::Create(Func: BswapOrBitreverse, Args: {ScalarX});
3429 }
3430 }
3431 }
3432
3433 // Handle the A->B->A cast, and there is an intervening PHI node.
3434 if (PHINode *PN = dyn_cast<PHINode>(Val: Src))
3435 if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
3436 return I;
3437
3438 if (Instruction *I = canonicalizeBitCastExtElt(BitCast&: CI, IC&: *this))
3439 return I;
3440
3441 if (Instruction *I = foldBitCastBitwiseLogic(BitCast&: CI, Builder))
3442 return I;
3443
3444 if (Instruction *I = foldBitCastSelect(BitCast&: CI, Builder))
3445 return I;
3446
3447 if (Value *V = foldCopySignIdioms(CI, Builder, SQ: SQ.getWithInstruction(I: &CI)))
3448 return replaceInstUsesWith(I&: CI, V);
3449
3450 return commonCastTransforms(CI);
3451}
3452
3453Instruction *InstCombinerImpl::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
3454 return commonCastTransforms(CI);
3455}
3456