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/ProfDataUtils.h"
26#include "llvm/IR/Type.h"
27#include "llvm/IR/Value.h"
28#include "llvm/Support/KnownBits.h"
29#include "llvm/Support/SaveAndRestore.h"
30#include "llvm/Transforms/InstCombine/InstCombiner.h"
31#include <optional>
32
33using namespace llvm;
34using namespace PatternMatch;
35
36#define DEBUG_TYPE "instcombine"
37
38using EvaluatedMap = SmallDenseMap<Value *, Value *, 8>;
39
40static Value *EvaluateInDifferentTypeImpl(Value *V, Type *Ty, bool isSigned,
41 InstCombinerImpl &IC,
42 EvaluatedMap &Processed) {
43 // Since we cover transformation of instructions with multiple users, we might
44 // come to the same node via multiple paths. We should not create a
45 // replacement for every single one of them though.
46 if (Value *Result = Processed.lookup(Val: V))
47 return Result;
48
49 if (Constant *C = dyn_cast<Constant>(Val: V))
50 return ConstantFoldIntegerCast(C, DestTy: Ty, IsSigned: isSigned, DL: IC.getDataLayout());
51
52 // Otherwise, it must be an instruction.
53 Instruction *I = cast<Instruction>(Val: V);
54 Instruction *Res = nullptr;
55 unsigned Opc = I->getOpcode();
56 switch (Opc) {
57 case Instruction::Add:
58 case Instruction::Sub:
59 case Instruction::Mul:
60 case Instruction::And:
61 case Instruction::Or:
62 case Instruction::Xor:
63 case Instruction::AShr:
64 case Instruction::LShr:
65 case Instruction::Shl:
66 case Instruction::UDiv:
67 case Instruction::URem: {
68 Value *LHS = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 0), Ty, isSigned, IC,
69 Processed);
70 Value *RHS = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty, isSigned, IC,
71 Processed);
72 Res = BinaryOperator::Create(Op: (Instruction::BinaryOps)Opc, S1: LHS, S2: RHS);
73 if (Opc == Instruction::LShr || Opc == Instruction::AShr)
74 Res->setIsExact(I->isExact());
75 break;
76 }
77 case Instruction::Trunc:
78 case Instruction::ZExt:
79 case Instruction::SExt:
80 // If the source type of the cast is the type we're trying for then we can
81 // just return the source. There's no need to insert it because it is not
82 // new.
83 if (I->getOperand(i: 0)->getType() == Ty)
84 return I->getOperand(i: 0);
85
86 // Otherwise, must be the same type of cast, so just reinsert a new one.
87 // This also handles the case of zext(trunc(x)) -> zext(x).
88 Res = CastInst::CreateIntegerCast(S: I->getOperand(i: 0), Ty,
89 isSigned: Opc == Instruction::SExt);
90 if (auto *Trunc = dyn_cast<TruncInst>(Val: I)) {
91 if (auto *NewTrunc = dyn_cast<TruncInst>(Val: Res)) {
92 if (Trunc->getType()->getScalarSizeInBits() <=
93 Ty->getScalarSizeInBits()) {
94 NewTrunc->setHasNoSignedWrap(Trunc->hasNoSignedWrap());
95 NewTrunc->setHasNoUnsignedWrap(Trunc->hasNoUnsignedWrap());
96 }
97 } else if (auto *NewZExt = dyn_cast<ZExtInst>(Val: Res)) {
98 if (Trunc->hasNoUnsignedWrap())
99 NewZExt->setNonNeg();
100 }
101 }
102 break;
103 case Instruction::Select: {
104 Value *True = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty, isSigned,
105 IC, Processed);
106 Value *False = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 2), Ty, isSigned,
107 IC, Processed);
108 Res = SelectInst::Create(C: I->getOperand(i: 0), S1: True, S2: False, NameStr: "", InsertBefore: nullptr,
109 MDFrom: ProfcheckDisableMetadataFixes ? nullptr : I);
110 break;
111 }
112 case Instruction::PHI: {
113 PHINode *OPN = cast<PHINode>(Val: I);
114 PHINode *NPN = PHINode::Create(Ty, NumReservedValues: OPN->getNumIncomingValues());
115 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
116 Value *V = EvaluateInDifferentTypeImpl(V: OPN->getIncomingValue(i), Ty,
117 isSigned, IC, Processed);
118 NPN->addIncoming(V, BB: OPN->getIncomingBlock(i));
119 }
120 Res = NPN;
121 break;
122 }
123 case Instruction::FPToUI:
124 case Instruction::FPToSI:
125 Res = CastInst::Create(static_cast<Instruction::CastOps>(Opc),
126 S: I->getOperand(i: 0), Ty);
127 break;
128 case Instruction::Call:
129 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
130 switch (II->getIntrinsicID()) {
131 default:
132 llvm_unreachable("Unsupported call!");
133 case Intrinsic::vscale: {
134 Function *Fn = Intrinsic::getOrInsertDeclaration(
135 M: I->getModule(), id: Intrinsic::vscale, OverloadTys: {Ty});
136 Res = CallInst::Create(Ty: Fn->getFunctionType(), F: Fn);
137 break;
138 }
139 case Intrinsic::umin:
140 case Intrinsic::umax:
141 case Intrinsic::smin:
142 case Intrinsic::smax: {
143 Value *Op0 = EvaluateInDifferentTypeImpl(V: II->getArgOperand(i: 0), Ty,
144 isSigned, IC, Processed);
145 Value *Op1 = EvaluateInDifferentTypeImpl(V: II->getArgOperand(i: 1), Ty,
146 isSigned, IC, Processed);
147 Function *Fn = Intrinsic::getOrInsertDeclaration(
148 M: I->getModule(), id: II->getIntrinsicID(), OverloadTys: {Ty});
149 Res = CallInst::Create(Ty: Fn->getFunctionType(), Func: Fn, Args: {Op0, Op1});
150 break;
151 }
152 case Intrinsic::abs: {
153 Value *Arg = EvaluateInDifferentTypeImpl(V: II->getArgOperand(i: 0), Ty,
154 isSigned, IC, Processed);
155 Function *Fn = Intrinsic::getOrInsertDeclaration(
156 M: I->getModule(), id: II->getIntrinsicID(), OverloadTys: {Ty});
157 Res = CallInst::Create(Ty: Fn->getFunctionType(), Func: Fn,
158 Args: {Arg, ConstantInt::getFalse(Context&: I->getContext())});
159 break;
160 }
161 }
162 }
163 break;
164 case Instruction::ShuffleVector: {
165 auto *ScalarTy = cast<VectorType>(Val: Ty)->getElementType();
166 auto *VTy = cast<VectorType>(Val: I->getOperand(i: 0)->getType());
167 auto *FixedTy = VectorType::get(ElementType: ScalarTy, EC: VTy->getElementCount());
168 Value *Op0 = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 0), Ty: FixedTy,
169 isSigned, IC, Processed);
170 Value *Op1 = EvaluateInDifferentTypeImpl(V: I->getOperand(i: 1), Ty: FixedTy,
171 isSigned, IC, Processed);
172 Res = new ShuffleVectorInst(Op0, Op1,
173 cast<ShuffleVectorInst>(Val: I)->getShuffleMask());
174 break;
175 }
176 default:
177 // TODO: Can handle more cases here.
178 llvm_unreachable("Unreachable!");
179 }
180
181 Res->takeName(V: I);
182 Value *Result = IC.InsertNewInstWith(New: Res, Old: I->getIterator());
183 // There is no need in keeping track of the old value/new value relationship
184 // when we have only one user, we came have here from that user and no-one
185 // else cares.
186 if (!V->hasOneUse())
187 Processed[V] = Result;
188
189 return Result;
190}
191
192/// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns
193/// true for, actually insert the code to evaluate the expression.
194Value *InstCombinerImpl::EvaluateInDifferentType(Value *V, Type *Ty,
195 bool isSigned) {
196 EvaluatedMap Processed;
197 return EvaluateInDifferentTypeImpl(V, Ty, isSigned, IC&: *this, Processed);
198}
199
200Instruction::CastOps
201InstCombinerImpl::isEliminableCastPair(const CastInst *CI1,
202 const CastInst *CI2) {
203 Type *SrcTy = CI1->getSrcTy();
204 Type *MidTy = CI1->getDestTy();
205 Type *DstTy = CI2->getDestTy();
206
207 Instruction::CastOps firstOp = CI1->getOpcode();
208 Instruction::CastOps secondOp = CI2->getOpcode();
209 Type *SrcIntPtrTy =
210 SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr;
211 Type *DstIntPtrTy =
212 DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr;
213 unsigned Res = CastInst::isEliminableCastPair(firstOpcode: firstOp, secondOpcode: secondOp, SrcTy, MidTy,
214 DstTy, DL: &DL);
215
216 // We don't want to form an inttoptr or ptrtoint that converts to an integer
217 // type that differs from the pointer size.
218 if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
219 (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
220 Res = 0;
221
222 return Instruction::CastOps(Res);
223}
224
225/// Implement the transforms common to all CastInst visitors.
226Instruction *InstCombinerImpl::commonCastTransforms(CastInst &CI) {
227 Value *Src = CI.getOperand(i_nocapture: 0);
228 Type *Ty = CI.getType();
229
230 if (Value *Res =
231 simplifyCastInst(CastOpc: CI.getOpcode(), Op: Src, Ty, Q: SQ.getWithInstruction(I: &CI)))
232 return replaceInstUsesWith(I&: CI, V: Res);
233
234 // Try to eliminate a cast of a cast.
235 if (auto *CSrc = dyn_cast<CastInst>(Val: Src)) { // A->B->C cast
236 if (Instruction::CastOps NewOpc = isEliminableCastPair(CI1: CSrc, CI2: &CI)) {
237 // The first cast (CSrc) is eliminable so we need to fix up or replace
238 // the second cast (CI). CSrc will then have a good chance of being dead.
239 auto *Res = CastInst::Create(NewOpc, S: CSrc->getOperand(i_nocapture: 0), Ty);
240 // Point debug users of the dying cast to the new one.
241 if (CSrc->hasOneUse())
242 replaceAllDbgUsesWith(From&: *CSrc, To&: *Res, DomPoint&: CI, DT);
243 return Res;
244 }
245 }
246
247 if (auto *Sel = dyn_cast<SelectInst>(Val: Src)) {
248 // We are casting a select. Try to fold the cast into the select if the
249 // select does not have a compare instruction with matching operand types
250 // or the select is likely better done in a narrow type.
251 // Creating a select with operands that are different sizes than its
252 // condition may inhibit other folds and lead to worse codegen.
253 Value *Cond = Sel->getCondition();
254 if (!isa<CmpInst, TruncInst>(Val: Cond) ||
255 cast<Instruction>(Val: Cond)->getOperand(i: 0)->getType() != Sel->getType() ||
256 (CI.getOpcode() == Instruction::Trunc &&
257 shouldChangeType(From: CI.getSrcTy(), To: CI.getType()))) {
258
259 // If it's a bitcast involving vectors, make sure it has the same number
260 // of elements on both sides.
261 if (CI.getOpcode() != Instruction::BitCast ||
262 match(V: &CI, P: m_ElementWiseBitCast(Op: m_Value()))) {
263 if (Instruction *NV = FoldOpIntoSelect(Op&: CI, SI: Sel)) {
264 replaceAllDbgUsesWith(From&: *Sel, To&: *NV, DomPoint&: CI, DT);
265 return NV;
266 }
267 }
268 }
269 }
270
271 // If we are casting a PHI, then fold the cast into the PHI.
272 if (auto *PN = dyn_cast<PHINode>(Val: Src)) {
273 // Don't do this if it would create a PHI node with an illegal type from a
274 // legal type.
275 if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() ||
276 shouldChangeType(From: CI.getSrcTy(), To: CI.getType()))
277 if (Instruction *NV = foldOpIntoPhi(I&: CI, PN))
278 return NV;
279 }
280
281 // Canonicalize a unary shuffle after the cast if neither operation changes
282 // the size or element size of the input vector.
283 // TODO: We could allow size-changing ops if that doesn't harm codegen.
284 // cast (shuffle X, Mask) --> shuffle (cast X), Mask
285 Value *X;
286 ArrayRef<int> Mask;
287 if (match(V: Src, P: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: X), v2: m_Poison(), mask: m_Mask(Mask))))) {
288 // TODO: Allow scalable vectors?
289 auto *SrcTy = dyn_cast<FixedVectorType>(Val: X->getType());
290 auto *DestTy = dyn_cast<FixedVectorType>(Val: Ty);
291 if (SrcTy && DestTy &&
292 SrcTy->getNumElements() == DestTy->getNumElements() &&
293 SrcTy->getPrimitiveSizeInBits() == DestTy->getPrimitiveSizeInBits()) {
294 Value *CastX = Builder.CreateCast(Op: CI.getOpcode(), V: X, DestTy);
295 return new ShuffleVectorInst(CastX, Mask);
296 }
297 }
298
299 return nullptr;
300}
301
302namespace {
303
304/// Helper class for evaluating whether a value can be computed in a different
305/// type without changing its value. Used by cast simplification transforms.
306class TypeEvaluationHelper {
307public:
308 /// Return true if we can evaluate the specified expression tree as type Ty
309 /// instead of its larger type, and arrive with the same value.
310 /// This is used by code that tries to eliminate truncates.
311 [[nodiscard]] static bool canEvaluateTruncated(Value *V, Type *Ty,
312 InstCombinerImpl &IC,
313 Instruction *CtxI);
314
315 /// Determine if the specified value can be computed in the specified wider
316 /// type and produce the same low bits. If not, return false.
317 [[nodiscard]] static bool canEvaluateZExtd(Value *V, Type *Ty,
318 unsigned &BitsToClear,
319 InstCombinerImpl &IC,
320 Instruction *CtxI);
321
322 /// Return true if we can take the specified value and return it as type Ty
323 /// without inserting any new casts and without changing the value of the
324 /// common low bits.
325 [[nodiscard]] static bool canEvaluateSExtd(Value *V, Type *Ty,
326 unsigned MaxTypeEvalDepth);
327
328private:
329 explicit TypeEvaluationHelper(unsigned MaxTypeEvalDepth)
330 : MaxTypeEvalDepth(MaxTypeEvalDepth) {}
331
332 /// Constants and extensions/truncates from the destination type are always
333 /// free to be evaluated in that type.
334 [[nodiscard]] static bool canAlwaysEvaluateInType(Value *V, Type *Ty);
335
336 /// Check if we traversed all the users of the multi-use values we've seen.
337 [[nodiscard]] bool allPendingVisited() const {
338 return llvm::all_of(Range: Pending,
339 P: [this](Value *V) { return Visited.contains(Val: V); });
340 }
341
342 /// A generic wrapper for canEvaluate* recursions to inject visitation
343 /// tracking and enforce correct multi-use value evaluations.
344 [[nodiscard]] bool
345 canEvaluate(Value *V, Type *Ty,
346 llvm::function_ref<bool(Value *, Type *Type)> Pred) {
347 if (Depth >= MaxTypeEvalDepth)
348 return false;
349
350 if (canAlwaysEvaluateInType(V, Ty))
351 return true;
352
353 auto *I = dyn_cast<Instruction>(Val: V);
354
355 if (I == nullptr)
356 return false;
357
358 // We insert false by default to return false when we encounter user loops.
359 const auto [It, Inserted] = Visited.insert(KV: {V, false});
360
361 // There are three possible cases for us having information on this value
362 // in the Visited map:
363 // 1. We properly checked it and concluded that we can evaluate it (true)
364 // 2. We properly checked it and concluded that we can't (false)
365 // 3. We started to check it, but during the recursive traversal we came
366 // back to it.
367 //
368 // For cases 1 and 2, we can safely return the stored result. For case 3, we
369 // can potentially have a situation where we can evaluate recursive user
370 // chains, but that can be quite tricky to do properly and isntead, we
371 // return false.
372 //
373 // In any case, we should return whatever was there in the map to begin
374 // with.
375 if (!Inserted)
376 return It->getSecond();
377
378 // We can easily make a decision about single-user values whether they can
379 // be evaluated in a different type or not, we came from that user. This is
380 // not as simple for multi-user values.
381 //
382 // In general, we have the following case (inverted control-flow, users are
383 // at the top):
384 //
385 // Cast %A
386 // ____|
387 // /
388 // %A = Use %B, %C
389 // ________| |
390 // / |
391 // %B = Use %D |
392 // ________| |
393 // / |
394 // %D = Use %C |
395 // ________|___|
396 // /
397 // %C = ...
398 //
399 // In this case, when we check %A, %B and %D, we are confident that we can
400 // make the decision here and now, since we came from their only users.
401 //
402 // For %C, it is harder. We come there twice, and when we come the first
403 // time, it's hard to tell if we will visit the second user (technically
404 // it's not hard, but we might need a lot of repetitive checks with non-zero
405 // cost).
406 //
407 // In the case above, we are allowed to evaluate %C in different type
408 // because all of it users were part of the traversal.
409 //
410 // In the following case, however, we can't make this conclusion:
411 //
412 // Cast %A
413 // ____|
414 // /
415 // %A = Use %B, %C
416 // ________| |
417 // / |
418 // %B = Use %D |
419 // ________| |
420 // / |
421 // %D = Use %C |
422 // | |
423 // foo(%C) | | <- never traversing foo(%C)
424 // ________|___|
425 // /
426 // %C = ...
427 //
428 // In this case, we still can evaluate %C in a different type, but we'd need
429 // to create a copy of the original %C to be used in foo(%C). Such
430 // duplication might be not profitable.
431 //
432 // For this reason, we collect all users of the mult-user values and mark
433 // them as "pending" and defer this decision to the very end. When we are
434 // done and and ready to have a positive verdict, we should double-check all
435 // of the pending users and ensure that we visited them. allPendingVisited
436 // predicate checks exactly that.
437 if (!I->hasOneUse()) {
438 for (Use &U : I->uses()) {
439 // For most instructions, evaluating them in a different type will
440 // change the type of all operands. This is not the case for select
441 // conditions. Make sure we don't retain an extra use via the select
442 // condition.
443 if (isa<SelectInst>(Val: U.getUser()) && U.getOperandNo() == 0)
444 return false;
445
446 Pending.push_back(Elt: U.getUser());
447 }
448 }
449
450 SaveAndRestore RestoreDepth(Depth, Depth + 1);
451 const bool Result = Pred(V, Ty);
452 // We have to set result this way and not via It because Pred is recursive
453 // and it is very likely that we grew Visited and invalidated It.
454 Visited[V] = Result;
455 return Result;
456 }
457
458 /// Filter out values that we can not evaluate in the destination type for
459 /// free.
460 [[nodiscard]] bool canNotEvaluateInType(Value *V, Type *Ty);
461
462 [[nodiscard]] bool canEvaluateTruncatedImpl(Value *V, Type *Ty,
463 InstCombinerImpl &IC,
464 Instruction *CtxI);
465 [[nodiscard]] bool canEvaluateTruncatedPred(Value *V, Type *Ty,
466 InstCombinerImpl &IC,
467 Instruction *CtxI);
468 [[nodiscard]] bool canEvaluateZExtdImpl(Value *V, Type *Ty,
469 unsigned &BitsToClear,
470 InstCombinerImpl &IC,
471 Instruction *CtxI);
472 [[nodiscard]] bool canEvaluateSExtdImpl(Value *V, Type *Ty);
473 [[nodiscard]] bool canEvaluateSExtdPred(Value *V, Type *Ty);
474
475 /// The recursion depth of this traversal.
476 unsigned Depth = 0;
477
478 const unsigned MaxTypeEvalDepth;
479
480 /// A bookkeeping map to memorize an already made decision for a traversed
481 /// value.
482 SmallDenseMap<Value *, bool, 8> Visited;
483
484 /// A list of pending values to check in the end.
485 SmallVector<Value *, 8> Pending;
486};
487
488} // anonymous namespace
489
490/// Constants and extensions/truncates from the destination type are always
491/// free to be evaluated in that type. This is a helper for canEvaluate*.
492bool TypeEvaluationHelper::canAlwaysEvaluateInType(Value *V, Type *Ty) {
493 if (isa<Constant>(Val: V))
494 return match(V, P: m_ImmConstant());
495
496 Value *X;
497 if (match(V, P: m_ZExtOrSExt(Op: m_SpecificType(RefTy: Ty, V&: X))) ||
498 match(V, P: m_Trunc(Op: m_SpecificType(RefTy: Ty, V&: X))))
499 return true;
500
501 return false;
502}
503
504/// Filter out values that we can not evaluate in the destination type for free.
505/// This is a helper for canEvaluate*.
506bool TypeEvaluationHelper::canNotEvaluateInType(Value *V, Type *Ty) {
507 if (!isa<Instruction>(Val: V))
508 return true;
509 // We don't extend or shrink something that has multiple uses -- doing so
510 // would require duplicating the instruction which isn't profitable.
511 if (!V->hasOneUse())
512 return true;
513
514 return false;
515}
516
517/// Return true if we can evaluate the specified expression tree as type Ty
518/// instead of its larger type, and arrive with the same value.
519/// This is used by code that tries to eliminate truncates.
520///
521/// Ty will always be a type smaller than V. We should return true if trunc(V)
522/// can be computed by computing V in the smaller type. If V is an instruction,
523/// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
524/// makes sense if x and y can be efficiently truncated.
525///
526/// This function works on both vectors and scalars.
527///
528bool TypeEvaluationHelper::canEvaluateTruncated(Value *V, Type *Ty,
529 InstCombinerImpl &IC,
530 Instruction *CtxI) {
531 TypeEvaluationHelper TYH(IC.CLOpts.max_type_eval_depth);
532 return TYH.canEvaluateTruncatedImpl(V, Ty, IC, CtxI) &&
533 // We need to check whether we visited all users of multi-user values,
534 // and we have to do it at the very end, outside of the recursion.
535 TYH.allPendingVisited();
536}
537
538bool TypeEvaluationHelper::canEvaluateTruncatedImpl(Value *V, Type *Ty,
539 InstCombinerImpl &IC,
540 Instruction *CtxI) {
541 return canEvaluate(V, Ty, Pred: [this, &IC, CtxI](Value *V, Type *Ty) {
542 return canEvaluateTruncatedPred(V, Ty, IC, CtxI);
543 });
544}
545
546bool TypeEvaluationHelper::canEvaluateTruncatedPred(Value *V, Type *Ty,
547 InstCombinerImpl &IC,
548 Instruction *CtxI) {
549 auto *I = cast<Instruction>(Val: V);
550 Type *OrigTy = V->getType();
551 switch (I->getOpcode()) {
552 case Instruction::Add:
553 case Instruction::Sub:
554 case Instruction::Mul:
555 case Instruction::And:
556 case Instruction::Or:
557 case Instruction::Xor:
558 // These operators can all arbitrarily be extended or truncated.
559 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
560 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
561
562 case Instruction::UDiv:
563 case Instruction::URem: {
564 // UDiv and URem can be truncated if all the truncated bits are zero.
565 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
566 uint32_t BitWidth = Ty->getScalarSizeInBits();
567 assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
568 APInt Mask = APInt::getBitsSetFrom(numBits: OrigBitWidth, loBit: BitWidth);
569 // Do not preserve the original context instruction. Simplifying div/rem
570 // based on later context may introduce a trap.
571 if (IC.MaskedValueIsZero(V: I->getOperand(i: 0), Mask, CtxI: I) &&
572 IC.MaskedValueIsZero(V: I->getOperand(i: 1), Mask, CtxI: I)) {
573 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
574 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
575 }
576 break;
577 }
578 case Instruction::Shl: {
579 // If we are truncating the result of this SHL, and if it's a shift of an
580 // inrange amount, we can always perform a SHL in a smaller type.
581 uint32_t BitWidth = Ty->getScalarSizeInBits();
582 KnownBits AmtKnownBits =
583 llvm::computeKnownBits(V: I->getOperand(i: 1), DL: IC.getDataLayout());
584 if (AmtKnownBits.getMaxValue().ult(RHS: BitWidth))
585 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
586 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
587 break;
588 }
589 case Instruction::LShr: {
590 // If this is a truncate of a logical shr, we can truncate it to a smaller
591 // lshr iff we know that the bits we would otherwise be shifting in are
592 // already zeros.
593 // TODO: It is enough to check that the bits we would be shifting in are
594 // zero - use AmtKnownBits.getMaxValue().
595 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
596 uint32_t BitWidth = Ty->getScalarSizeInBits();
597 KnownBits AmtKnownBits = IC.computeKnownBits(V: I->getOperand(i: 1), CtxI);
598 APInt MaxShiftAmt = AmtKnownBits.getMaxValue();
599 APInt ShiftedBits = APInt::getBitsSetFrom(numBits: OrigBitWidth, loBit: BitWidth);
600 if (MaxShiftAmt.ult(RHS: BitWidth)) {
601 // If the only user is a trunc then we can narrow the shift if any new
602 // MSBs are not going to be used.
603 if (auto *Trunc = dyn_cast<TruncInst>(Val: V->user_back())) {
604 auto DemandedBits = Trunc->getType()->getScalarSizeInBits();
605 if ((MaxShiftAmt + DemandedBits).ule(RHS: BitWidth))
606 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
607 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
608 }
609 if (IC.MaskedValueIsZero(V: I->getOperand(i: 0), Mask: ShiftedBits, CtxI))
610 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
611 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
612 }
613 break;
614 }
615 case Instruction::AShr: {
616 // If this is a truncate of an arithmetic shr, we can truncate it to a
617 // smaller ashr iff we know that all the bits from the sign bit of the
618 // original type and the sign bit of the truncate type are similar.
619 // TODO: It is enough to check that the bits we would be shifting in are
620 // similar to sign bit of the truncate type.
621 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
622 uint32_t BitWidth = Ty->getScalarSizeInBits();
623 KnownBits AmtKnownBits =
624 llvm::computeKnownBits(V: I->getOperand(i: 1), DL: IC.getDataLayout());
625 unsigned ShiftedBits = OrigBitWidth - BitWidth;
626 if (AmtKnownBits.getMaxValue().ult(RHS: BitWidth) &&
627 ShiftedBits < IC.ComputeNumSignBits(Op: I->getOperand(i: 0), CtxI))
628 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
629 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
630 break;
631 }
632 case Instruction::Trunc:
633 // trunc(trunc(x)) -> trunc(x)
634 return true;
635 case Instruction::ZExt:
636 case Instruction::SExt:
637 // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
638 // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
639 return true;
640 case Instruction::Select: {
641 SelectInst *SI = cast<SelectInst>(Val: I);
642 return canEvaluateTruncatedImpl(V: SI->getTrueValue(), Ty, IC, CtxI) &&
643 canEvaluateTruncatedImpl(V: SI->getFalseValue(), Ty, IC, CtxI);
644 }
645 case Instruction::PHI: {
646 // We can change a phi if we can change all operands. Note that we never
647 // get into trouble with cyclic PHIs here because canEvaluate handles use
648 // chain loops.
649 PHINode *PN = cast<PHINode>(Val: I);
650 return llvm::all_of(
651 Range: PN->incoming_values(), P: [this, Ty, &IC, CtxI](Value *IncValue) {
652 return canEvaluateTruncatedImpl(V: IncValue, Ty, IC, CtxI);
653 });
654 }
655 case Instruction::FPToUI:
656 case Instruction::FPToSI: {
657 // If the integer type can hold the max FP value, it is safe to cast
658 // directly to that type. Otherwise, we may create poison via overflow
659 // that did not exist in the original code.
660 Type *InputTy = I->getOperand(i: 0)->getType()->getScalarType();
661 const fltSemantics &Semantics = InputTy->getFltSemantics();
662 uint32_t MinBitWidth = APFloatBase::semanticsIntSizeInBits(
663 Semantics, I->getOpcode() == Instruction::FPToSI);
664 return Ty->getScalarSizeInBits() >= MinBitWidth;
665 }
666 case Instruction::ShuffleVector:
667 return canEvaluateTruncatedImpl(V: I->getOperand(i: 0), Ty, IC, CtxI) &&
668 canEvaluateTruncatedImpl(V: I->getOperand(i: 1), Ty, IC, CtxI);
669
670 case Instruction::Call: {
671 Value *AbsOp;
672 if (match(V: I, P: m_Intrinsic<Intrinsic::abs>(Ops: m_Value(V&: AbsOp), Ops: m_Value()))) {
673 if (IC.ComputeMaxSignificantBits(Op: AbsOp, CtxI) > Ty->getScalarSizeInBits())
674 return false;
675 return canEvaluateTruncatedImpl(V: AbsOp, Ty, IC, CtxI);
676 }
677 auto *MM = dyn_cast<MinMaxIntrinsic>(Val: I);
678 if (!MM)
679 return false;
680 // The min/max can be performed in the narrow type when each operand has
681 // zero high bits (for umin/umax) or enough sign bits (for smin/smax).
682 Value *Op0 = MM->getLHS();
683 Value *Op1 = MM->getRHS();
684 uint32_t BitWidth = Ty->getScalarSizeInBits();
685 if (MM->isSigned()) {
686 if (IC.ComputeMaxSignificantBits(Op: Op0, CtxI) > BitWidth ||
687 IC.ComputeMaxSignificantBits(Op: Op1, CtxI) > BitWidth)
688 break;
689 } else {
690 APInt Mask =
691 APInt::getBitsSetFrom(numBits: OrigTy->getScalarSizeInBits(), loBit: BitWidth);
692 if (!IC.MaskedValueIsZero(V: Op0, Mask, CtxI) ||
693 !IC.MaskedValueIsZero(V: Op1, Mask, CtxI))
694 break;
695 }
696 return canEvaluateTruncatedImpl(V: Op0, Ty, IC, CtxI) &&
697 canEvaluateTruncatedImpl(V: Op1, Ty, IC, CtxI);
698 }
699 default:
700 // TODO: Can handle more cases here.
701 break;
702 }
703
704 return false;
705}
706
707/// Given a vector that is bitcast to an integer, optionally logically
708/// right-shifted, and truncated, convert it to an extractelement.
709/// Example (big endian):
710/// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32
711/// --->
712/// extractelement <4 x i32> %X, 1
713static Instruction *foldVecTruncToExtElt(TruncInst &Trunc,
714 InstCombinerImpl &IC) {
715 Value *TruncOp = Trunc.getOperand(i_nocapture: 0);
716 Type *DestType = Trunc.getType();
717 if (!TruncOp->hasOneUse() || !isa<IntegerType>(Val: DestType))
718 return nullptr;
719
720 Value *VecInput = nullptr;
721 ConstantInt *ShiftVal = nullptr;
722 if (!match(V: TruncOp, P: m_CombineOr(Ps: m_BitCast(Op: m_Value(V&: VecInput)),
723 Ps: m_LShr(L: m_BitCast(Op: m_Value(V&: VecInput)),
724 R: m_ConstantInt(CI&: ShiftVal)))) ||
725 !isa<VectorType>(Val: VecInput->getType()))
726 return nullptr;
727
728 VectorType *VecType = cast<VectorType>(Val: VecInput->getType());
729 unsigned VecWidth = VecType->getPrimitiveSizeInBits();
730 unsigned DestWidth = DestType->getPrimitiveSizeInBits();
731 unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0;
732
733 if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0))
734 return nullptr;
735
736 // If the element type of the vector doesn't match the result type,
737 // bitcast it to a vector type that we can extract from.
738 unsigned NumVecElts = VecWidth / DestWidth;
739 if (VecType->getElementType() != DestType) {
740 VecType = FixedVectorType::get(ElementType: DestType, NumElts: NumVecElts);
741 VecInput = IC.Builder.CreateBitCast(V: VecInput, DestTy: VecType, Name: "bc");
742 }
743
744 unsigned Elt = ShiftAmount / DestWidth;
745 if (IC.getDataLayout().isBigEndian())
746 Elt = NumVecElts - 1 - Elt;
747
748 return ExtractElementInst::Create(Vec: VecInput, Idx: IC.Builder.getInt32(C: Elt));
749}
750
751/// Whenever an element is extracted from a vector, optionally shifted down, and
752/// then truncated, canonicalize by converting it to a bitcast followed by an
753/// extractelement.
754///
755/// Examples (little endian):
756/// trunc (extractelement <4 x i64> %X, 0) to i32
757/// --->
758/// extractelement <8 x i32> (bitcast <4 x i64> %X to <8 x i32>), i32 0
759///
760/// trunc (lshr (extractelement <4 x i32> %X, 0), 8) to i8
761/// --->
762/// extractelement <16 x i8> (bitcast <4 x i32> %X to <16 x i8>), i32 1
763static Instruction *foldVecExtTruncToExtElt(TruncInst &Trunc,
764 InstCombinerImpl &IC) {
765 Value *Src = Trunc.getOperand(i_nocapture: 0);
766 Type *SrcType = Src->getType();
767 Type *DstType = Trunc.getType();
768
769 // Only attempt this if we have simple aliasing of the vector elements.
770 // A badly fit destination size would result in an invalid cast.
771 unsigned SrcBits = SrcType->getScalarSizeInBits();
772 unsigned DstBits = DstType->getScalarSizeInBits();
773 uint64_t TruncRatio = SrcBits / DstBits;
774 if ((SrcBits % DstBits) != 0)
775 return nullptr;
776
777 Value *VecOp;
778 ConstantInt *Cst;
779 const APInt *ShiftAmount = nullptr;
780 if (!match(V: Src, P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_ConstantInt(CI&: Cst)))) &&
781 !match(V: Src,
782 P: m_OneUse(SubPattern: m_LShr(L: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_ConstantInt(CI&: Cst)),
783 R: m_APInt(Res&: ShiftAmount)))))
784 return nullptr;
785
786 auto *VecOpTy = cast<VectorType>(Val: VecOp->getType());
787 auto VecElts = VecOpTy->getElementCount();
788
789 uint64_t BitCastNumElts = VecElts.getKnownMinValue() * TruncRatio;
790 // Computed in 64-bit above to avoid a 32-bit overflow. Bail out if the
791 // element count exceeds IntegerType::MAX_INT_BITS, as we cannot create a
792 // wider vector type.
793 if (BitCastNumElts > IntegerType::MAX_INT_BITS)
794 return nullptr;
795 // Make sure we don't overflow in the calculation of the new index.
796 // (VecOpIdx + 1) * TruncRatio should not overflow.
797 if (Cst->uge(Num: std::numeric_limits<uint64_t>::max() / TruncRatio))
798 return nullptr;
799 uint64_t VecOpIdx = Cst->getZExtValue();
800 uint64_t NewIdx = IC.getDataLayout().isBigEndian()
801 ? (VecOpIdx + 1) * TruncRatio - 1
802 : VecOpIdx * TruncRatio;
803
804 // Adjust index by the whole number of truncated elements.
805 if (ShiftAmount) {
806 // Check shift amount is in range and shifts a whole number of truncated
807 // elements.
808 if (ShiftAmount->uge(RHS: SrcBits) || ShiftAmount->urem(RHS: DstBits) != 0)
809 return nullptr;
810
811 uint64_t IdxOfs = ShiftAmount->udiv(RHS: DstBits).getZExtValue();
812 // IdxOfs is guaranteed to be less than TruncRatio, so we won't overflow in
813 // the adjustment.
814 assert(IdxOfs < TruncRatio &&
815 "IdxOfs is expected to be less than TruncRatio.");
816 NewIdx = IC.getDataLayout().isBigEndian() ? (NewIdx - IdxOfs)
817 : (NewIdx + IdxOfs);
818 }
819
820 auto *BitCastTo =
821 VectorType::get(ElementType: DstType, NumElements: BitCastNumElts, Scalable: VecElts.isScalable());
822 Value *BitCast = IC.Builder.CreateBitCast(V: VecOp, DestTy: BitCastTo);
823 return ExtractElementInst::Create(Vec: BitCast, Idx: IC.Builder.getInt64(C: NewIdx));
824}
825
826/// Funnel/Rotate left/right may occur in a wider type than necessary because of
827/// type promotion rules. Try to narrow the inputs and convert to funnel shift.
828Instruction *InstCombinerImpl::narrowFunnelShift(TruncInst &Trunc) {
829 assert((isa<VectorType>(Trunc.getSrcTy()) ||
830 shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) &&
831 "Don't narrow to an illegal scalar type");
832
833 // Bail out on strange types. It is possible to handle some of these patterns
834 // even with non-power-of-2 sizes, but it is not a likely scenario.
835 Type *DestTy = Trunc.getType();
836 unsigned NarrowWidth = DestTy->getScalarSizeInBits();
837 unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
838 if (!isPowerOf2_32(Value: NarrowWidth))
839 return nullptr;
840
841 // First, find an or'd pair of opposite shifts:
842 // trunc (or (lshr ShVal0, ShAmt0), (shl ShVal1, ShAmt1))
843 BinaryOperator *Or0, *Or1;
844 if (!match(V: Trunc.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_Or(L: m_BinOp(I&: Or0), R: m_BinOp(I&: Or1)))))
845 return nullptr;
846
847 Value *ShVal0, *ShVal1, *ShAmt0, *ShAmt1;
848 if (!match(V: Or0, P: m_OneUse(SubPattern: m_LogicalShift(L: m_Value(V&: ShVal0), R: m_Value(V&: ShAmt0)))) ||
849 !match(V: Or1, P: m_OneUse(SubPattern: m_LogicalShift(L: m_Value(V&: ShVal1), R: m_Value(V&: ShAmt1)))) ||
850 Or0->getOpcode() == Or1->getOpcode())
851 return nullptr;
852
853 // Canonicalize to or(shl(ShVal0, ShAmt0), lshr(ShVal1, ShAmt1)).
854 if (Or0->getOpcode() == BinaryOperator::LShr) {
855 std::swap(a&: Or0, b&: Or1);
856 std::swap(a&: ShVal0, b&: ShVal1);
857 std::swap(a&: ShAmt0, b&: ShAmt1);
858 }
859 assert(Or0->getOpcode() == BinaryOperator::Shl &&
860 Or1->getOpcode() == BinaryOperator::LShr &&
861 "Illegal or(shift,shift) pair");
862
863 // Match the shift amount operands for a funnel/rotate pattern. This always
864 // matches a subtraction on the R operand.
865 auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
866 // The shift amounts may add up to the narrow bit width:
867 // (shl ShVal0, L) | (lshr ShVal1, Width - L)
868 // If this is a funnel shift (different operands are shifted), then the
869 // shift amount can not over-shift (create poison) in the narrow type.
870 unsigned MaxShiftAmountWidth = Log2_32(Value: NarrowWidth);
871 APInt HiBitMask = ~APInt::getLowBitsSet(numBits: WideWidth, loBitsSet: MaxShiftAmountWidth);
872 if (ShVal0 == ShVal1 || MaskedValueIsZero(V: L, Mask: HiBitMask))
873 if (match(V: R, P: m_OneUse(SubPattern: m_Sub(L: m_SpecificInt(V: Width), R: m_Specific(V: L)))))
874 return L;
875
876 // The following patterns currently only work for rotation patterns.
877 // TODO: Add more general funnel-shift compatible patterns.
878 if (ShVal0 != ShVal1)
879 return nullptr;
880
881 // The shift amount may be masked with negation:
882 // (shl ShVal0, (X & (Width - 1))) | (lshr ShVal1, ((-X) & (Width - 1)))
883 Value *X;
884 unsigned Mask = Width - 1;
885 if (match(V: L, P: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: Mask))) &&
886 match(V: R, P: m_And(L: m_Neg(V: m_Specific(V: X)), R: m_SpecificInt(V: Mask))))
887 return X;
888
889 // Same as above, but the shift amount may be extended after masking:
890 if (match(V: L, P: m_ZExt(Op: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: Mask)))) &&
891 match(V: R, P: m_ZExt(Op: m_And(L: m_Neg(V: m_Specific(V: X)), R: m_SpecificInt(V: Mask)))))
892 return X;
893
894 return nullptr;
895 };
896
897 Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth);
898 bool IsFshl = true; // Sub on LSHR.
899 if (!ShAmt) {
900 ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth);
901 IsFshl = false; // Sub on SHL.
902 }
903 if (!ShAmt)
904 return nullptr;
905
906 // The right-shifted value must have high zeros in the wide type (for example
907 // from 'zext', 'and' or 'shift'). High bits of the left-shifted value are
908 // truncated, so those do not matter.
909 APInt HiBitMask = APInt::getHighBitsSet(numBits: WideWidth, hiBitsSet: WideWidth - NarrowWidth);
910 if (!MaskedValueIsZero(V: ShVal1, Mask: HiBitMask, CtxI: &Trunc))
911 return nullptr;
912
913 // Adjust the width of ShAmt for narrowed funnel shift operation:
914 // - Zero-extend if ShAmt is narrower than the destination type.
915 // - Truncate if ShAmt is wider, discarding non-significant high-order bits.
916 // This prepares ShAmt for llvm.fshl.i8(trunc(ShVal), trunc(ShVal),
917 // zext/trunc(ShAmt)).
918 Value *NarrowShAmt = Builder.CreateZExtOrTrunc(V: ShAmt, DestTy);
919
920 Value *X, *Y;
921 X = Y = Builder.CreateTrunc(V: ShVal0, DestTy);
922 if (ShVal0 != ShVal1)
923 Y = Builder.CreateTrunc(V: ShVal1, DestTy);
924 Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
925 Function *F =
926 Intrinsic::getOrInsertDeclaration(M: Trunc.getModule(), id: IID, OverloadTys: DestTy);
927 return CallInst::Create(Func: F, Args: {X, Y, NarrowShAmt});
928}
929
930/// Try to narrow the width of math or bitwise logic instructions by pulling a
931/// truncate ahead of binary operators.
932Instruction *InstCombinerImpl::narrowBinOp(TruncInst &Trunc) {
933 Type *SrcTy = Trunc.getSrcTy();
934 Type *DestTy = Trunc.getType();
935 unsigned SrcWidth = SrcTy->getScalarSizeInBits();
936 unsigned DestWidth = DestTy->getScalarSizeInBits();
937
938 if (!isa<VectorType>(Val: SrcTy) && !shouldChangeType(From: SrcTy, To: DestTy))
939 return nullptr;
940
941 BinaryOperator *BinOp;
942 if (!match(V: Trunc.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BinOp))))
943 return nullptr;
944
945 Value *BinOp0 = BinOp->getOperand(i_nocapture: 0);
946 Value *BinOp1 = BinOp->getOperand(i_nocapture: 1);
947 switch (BinOp->getOpcode()) {
948 case Instruction::And:
949 case Instruction::Or:
950 case Instruction::Xor:
951 case Instruction::Add:
952 case Instruction::Sub:
953 case Instruction::Mul: {
954 Constant *C;
955 if (match(V: BinOp0, P: m_Constant(C))) {
956 // trunc (binop C, X) --> binop (trunc C', X)
957 Constant *NarrowC = ConstantExpr::getTrunc(C, Ty: DestTy);
958 Value *TruncX = Builder.CreateTrunc(V: BinOp1, DestTy);
959 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: NarrowC, S2: TruncX);
960 }
961 if (match(V: BinOp1, P: m_Constant(C))) {
962 // trunc (binop X, C) --> binop (trunc X, C')
963 Constant *NarrowC = ConstantExpr::getTrunc(C, Ty: DestTy);
964 Value *TruncX = Builder.CreateTrunc(V: BinOp0, DestTy);
965 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: TruncX, S2: NarrowC);
966 }
967 Value *X;
968 if (match(V: BinOp0, P: m_ZExtOrSExt(Op: m_SpecificType(RefTy: DestTy, V&: X)))) {
969 // trunc (binop (ext X), Y) --> binop X, (trunc Y)
970 Value *NarrowOp1 = Builder.CreateTrunc(V: BinOp1, DestTy);
971 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: X, S2: NarrowOp1);
972 }
973 if (match(V: BinOp1, P: m_ZExtOrSExt(Op: m_SpecificType(RefTy: DestTy, V&: X)))) {
974 // trunc (binop Y, (ext X)) --> binop (trunc Y), X
975 Value *NarrowOp0 = Builder.CreateTrunc(V: BinOp0, DestTy);
976 return BinaryOperator::Create(Op: BinOp->getOpcode(), S1: NarrowOp0, S2: X);
977 }
978 break;
979 }
980 case Instruction::LShr:
981 case Instruction::AShr: {
982 // trunc (*shr (trunc A), C) --> trunc(*shr A, C)
983 Value *A;
984 Constant *C;
985 if (match(V: BinOp0, P: m_Trunc(Op: m_Value(V&: A))) && match(V: BinOp1, P: m_Constant(C))) {
986 unsigned MaxShiftAmt = SrcWidth - DestWidth;
987 // If the shift is small enough, all zero/sign bits created by the shift
988 // are removed by the trunc.
989 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
990 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
991 auto *OldShift = cast<Instruction>(Val: Trunc.getOperand(i_nocapture: 0));
992 bool IsExact = OldShift->isExact();
993 if (Constant *ShAmt = ConstantFoldIntegerCast(C, DestTy: A->getType(),
994 /*IsSigned*/ true, DL)) {
995 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
996 Value *Shift =
997 OldShift->getOpcode() == Instruction::AShr
998 ? Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: OldShift->getName(), isExact: IsExact)
999 : Builder.CreateLShr(LHS: A, RHS: ShAmt, Name: OldShift->getName(), isExact: IsExact);
1000 return CastInst::CreateTruncOrBitCast(S: Shift, Ty: DestTy);
1001 }
1002 }
1003 }
1004 break;
1005 }
1006 default: break;
1007 }
1008
1009 if (Instruction *NarrowOr = narrowFunnelShift(Trunc))
1010 return NarrowOr;
1011
1012 return nullptr;
1013}
1014
1015/// Try to narrow the width of a splat shuffle. This could be generalized to any
1016/// shuffle with a constant operand, but we limit the transform to avoid
1017/// creating a shuffle type that targets may not be able to lower effectively.
1018static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
1019 InstCombiner::BuilderTy &Builder) {
1020 Value *Shuf = Trunc.getOperand(i_nocapture: 0), *ShufVec;
1021 ArrayRef<int> SplatMask;
1022 if (match(V: Shuf, P: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: ShufVec), v2: m_Poison(),
1023 mask: m_Mask(SplatMask)))) &&
1024 match(Mask: SplatMask, P: m_SplatMask()) &&
1025 ElementCount::isKnownGE(
1026 LHS: cast<VectorType>(Val: Shuf->getType())->getElementCount(),
1027 RHS: cast<VectorType>(Val: ShufVec->getType())->getElementCount())) {
1028 // trunc (shuf X, poison, SplatMask) --> shuf (trunc X), poison, SplatMask
1029 Type *NewTruncTy =
1030 ShufVec->getType()->getWithNewType(EltTy: Trunc.getType()->getScalarType());
1031 Value *NarrowOp = Builder.CreateTrunc(V: ShufVec, DestTy: NewTruncTy);
1032 return new ShuffleVectorInst(NarrowOp, SplatMask);
1033 }
1034
1035 return nullptr;
1036}
1037
1038/// Try to narrow the width of an insert element. This could be generalized for
1039/// any vector constant, but we limit the transform to insertion into poison to
1040/// avoid potential backend problems from unsupported insertion widths. This
1041/// could also be extended to handle the case of inserting a scalar constant
1042/// into a vector variable.
1043static Instruction *shrinkInsertElt(CastInst &Trunc,
1044 InstCombiner::BuilderTy &Builder) {
1045 Instruction::CastOps Opcode = Trunc.getOpcode();
1046 assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
1047 "Unexpected instruction for shrinking");
1048
1049 Value *Elt, *Index;
1050 if (match(V: Trunc.getOperand(i_nocapture: 0),
1051 P: m_OneUse(SubPattern: m_InsertElt(Val: m_Poison(), Elt: m_Value(V&: Elt), Idx: m_Value(V&: Index))))) {
1052 // trunc (inselt poison, X, Index) --> inselt poison, (trunc X), Index
1053 // fptrunc (inselt poison, X, Index) --> inselt poison, (fptrunc X), Index
1054 auto *NarrowPoison = PoisonValue::get(T: Trunc.getType());
1055 Value *NarrowOp =
1056 Builder.CreateCast(Op: Opcode, V: Elt, DestTy: Trunc.getType()->getScalarType());
1057 return InsertElementInst::Create(Vec: NarrowPoison, NewElt: NarrowOp, Idx: Index);
1058 }
1059
1060 return nullptr;
1061}
1062
1063Instruction *InstCombinerImpl::visitTrunc(TruncInst &Trunc) {
1064 if (Instruction *Result = commonCastTransforms(CI&: Trunc))
1065 return Result;
1066
1067 Value *Src = Trunc.getOperand(i_nocapture: 0);
1068 Type *DestTy = Trunc.getType(), *SrcTy = Src->getType();
1069 unsigned DestWidth = DestTy->getScalarSizeInBits();
1070 unsigned SrcWidth = SrcTy->getScalarSizeInBits();
1071
1072 // Attempt to truncate the entire input expression tree to the destination
1073 // type. Only do this if the dest type is a simple type, don't convert the
1074 // expression tree to something weird like i93 unless the source is also
1075 // strange.
1076 if ((DestTy->isVectorTy() || shouldChangeType(From: SrcTy, To: DestTy)) &&
1077 TypeEvaluationHelper::canEvaluateTruncated(V: Src, Ty: DestTy, IC&: *this, CtxI: &Trunc)) {
1078
1079 // If this cast is a truncate, evaluting in a different type always
1080 // eliminates the cast, so it is always a win.
1081 LLVM_DEBUG(
1082 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1083 " to avoid cast: "
1084 << Trunc << '\n');
1085 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: false);
1086 assert(Res->getType() == DestTy);
1087 return replaceInstUsesWith(I&: Trunc, V: Res);
1088 }
1089
1090 // For integer types, check if we can shorten the entire input expression to
1091 // DestWidth * 2, which won't allow removing the truncate, but reducing the
1092 // width may enable further optimizations, e.g. allowing for larger
1093 // vectorization factors.
1094 if (auto *DestITy = dyn_cast<IntegerType>(Val: DestTy)) {
1095 if (DestWidth * 2 < SrcWidth) {
1096 auto *NewDestTy = DestITy->getExtendedType();
1097 if (shouldChangeType(From: SrcTy, To: NewDestTy) &&
1098 TypeEvaluationHelper::canEvaluateTruncated(V: Src, Ty: NewDestTy, IC&: *this,
1099 CtxI: &Trunc)) {
1100 LLVM_DEBUG(
1101 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1102 " to reduce the width of operand of"
1103 << Trunc << '\n');
1104 Value *Res = EvaluateInDifferentType(V: Src, Ty: NewDestTy, isSigned: false);
1105 return new TruncInst(Res, DestTy);
1106 }
1107 }
1108 }
1109 Value *X;
1110 if (DestWidth == 1 &&
1111 (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) &&
1112 match(V: Src, P: m_Exact(SubPattern: m_Shr(L: m_Value(V&: X), R: m_Value()))))
1113 return new ICmpInst(ICmpInst::ICMP_NE, X, Constant::getNullValue(Ty: SrcTy));
1114
1115 // See if we can simplify any instructions used by the input whose sole
1116 // purpose is to compute bits we don't care about.
1117 if (SimplifyDemandedInstructionBits(Inst&: Trunc))
1118 return &Trunc;
1119
1120 if (DestWidth == 1) {
1121 Value *Zero = Constant::getNullValue(Ty: SrcTy);
1122
1123 const APInt *C1;
1124 Constant *C2;
1125 if (match(V: Src, P: m_OneUse(SubPattern: m_Shr(L: m_Shl(L: m_Power2(V&: C1), R: m_Value(V&: X)),
1126 R: m_ImmConstant(C&: C2))))) {
1127 // trunc ((C1 << X) >> C2) to i1 --> X == (C2-cttz(C1)), where C1 is pow2
1128 Constant *Log2C1 = ConstantInt::get(Ty: SrcTy, V: C1->exactLogBase2());
1129 Constant *CmpC = ConstantExpr::getSub(C1: C2, C2: Log2C1);
1130 return new ICmpInst(ICmpInst::ICMP_EQ, X, CmpC);
1131 }
1132
1133 if (match(V: Src, P: m_Shr(L: m_Value(V&: X), R: m_SpecificInt(V: SrcWidth - 1)))) {
1134 // trunc (ashr X, BW-1) to i1 --> icmp slt X, 0
1135 // trunc (lshr X, BW-1) to i1 --> icmp slt X, 0
1136 return new ICmpInst(ICmpInst::ICMP_SLT, X, Zero);
1137 }
1138
1139 Constant *C;
1140 if (match(V: Src, P: m_OneUse(SubPattern: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C))))) {
1141 // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
1142 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1143 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1144 Value *And = Builder.CreateAnd(LHS: X, RHS: MaskC);
1145 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1146 }
1147 if (match(V: Src, P: m_OneUse(SubPattern: m_c_Or(L: m_LShr(L: m_Value(V&: X), R: m_ImmConstant(C)),
1148 R: m_Deferred(V: X))))) {
1149 // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
1150 Constant *One = ConstantInt::get(Ty: SrcTy, V: APInt(SrcWidth, 1));
1151 Value *MaskC = Builder.CreateShl(LHS: One, RHS: C);
1152 Value *And = Builder.CreateAnd(LHS: X, RHS: Builder.CreateOr(LHS: MaskC, RHS: One));
1153 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1154 }
1155
1156 {
1157 const APInt *C;
1158 if (match(V: Src, P: m_Shl(L: m_APInt(Res&: C), R: m_Value(V&: X))) && (*C)[0] == 1) {
1159 // trunc (C << X) to i1 --> X == 0, where C is odd
1160 return new ICmpInst(ICmpInst::Predicate::ICMP_EQ, X, Zero);
1161 }
1162 }
1163
1164 if (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) {
1165 Value *X, *Y;
1166 if (match(V: Src, P: m_Xor(L: m_Value(V&: X), R: m_Value(V&: Y))))
1167 return new ICmpInst(ICmpInst::ICMP_NE, X, Y);
1168 }
1169
1170 if (match(V: Src,
1171 P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::usub_sat>(Ops: m_One(), Ops: m_Value(V&: X)))))
1172 return new ICmpInst(ICmpInst::ICMP_EQ, X,
1173 ConstantInt::getNullValue(Ty: SrcTy));
1174 }
1175
1176 Value *A, *B;
1177 Constant *C;
1178
1179 // trunc(u/smin(zext(a) + zext(b), MAX)) --> uadd.sat(a, b)
1180 if (match(V: Src, P: m_OneUse(SubPattern: m_CombineOr(
1181 Ps: m_UMin(Op0: m_OneUse(SubPattern: m_Add(L: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: A)),
1182 R: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: B)))),
1183 Op1: m_SpecificInt(V: APInt::getMaxValue(numBits: DestWidth))),
1184 Ps: m_SMin(Op0: m_OneUse(SubPattern: m_Add(L: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: A)),
1185 R: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: B)))),
1186 Op1: m_SpecificInt(V: APInt::getMaxValue(numBits: DestWidth))))))) {
1187 return replaceInstUsesWith(
1188 I&: Trunc, V: Builder.CreateBinaryIntrinsic(ID: Intrinsic::uadd_sat, LHS: A, RHS: B));
1189 }
1190
1191 // trunc(smax(zext(a) - zext(b), 0)) --> usub.sat(a, b)
1192 if (match(V: Src,
1193 P: m_OneUse(SubPattern: m_SMax(Op0: m_OneUse(SubPattern: m_Sub(L: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: A)),
1194 R: m_ZExt(Op: m_SpecificType(RefTy: DestTy, V&: B)))),
1195 Op1: m_Zero())))) {
1196 return replaceInstUsesWith(
1197 I&: Trunc, V: Builder.CreateBinaryIntrinsic(ID: Intrinsic::usub_sat, LHS: A, RHS: B));
1198 }
1199
1200 if (match(V: Src, P: m_LShr(L: m_SExt(Op: m_Value(V&: A)), R: m_Constant(C)))) {
1201 unsigned AWidth = A->getType()->getScalarSizeInBits();
1202 unsigned MaxShiftAmt = SrcWidth - std::max(a: DestWidth, b: AWidth);
1203 auto *OldSh = cast<Instruction>(Val: Src);
1204 bool IsExact = OldSh->isExact();
1205
1206 // If the shift is small enough, all zero bits created by the shift are
1207 // removed by the trunc.
1208 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULE,
1209 Threshold: APInt(SrcWidth, MaxShiftAmt)))) {
1210 auto GetNewShAmt = [&](unsigned Width) {
1211 Constant *MaxAmt = ConstantInt::get(Ty: SrcTy, V: Width - 1, IsSigned: false);
1212 Constant *Cmp =
1213 ConstantFoldCompareInstOperands(Predicate: ICmpInst::ICMP_ULT, LHS: C, RHS: MaxAmt, DL);
1214 Constant *ShAmt = ConstantFoldSelectInstruction(Cond: Cmp, V1: C, V2: MaxAmt);
1215 return ConstantFoldCastOperand(Opcode: Instruction::Trunc, C: ShAmt, DestTy: A->getType(),
1216 DL);
1217 };
1218
1219 // trunc (lshr (sext A), C) --> ashr A, C
1220 if (A->getType() == DestTy) {
1221 Constant *ShAmt = GetNewShAmt(DestWidth);
1222 ShAmt = Constant::mergeUndefsWith(C: ShAmt, Other: C);
1223 return IsExact ? BinaryOperator::CreateExactAShr(V1: A, V2: ShAmt)
1224 : BinaryOperator::CreateAShr(V1: A, V2: ShAmt);
1225 }
1226 // The types are mismatched, so create a cast after shifting:
1227 // trunc (lshr (sext A), C) --> sext/trunc (ashr A, C)
1228 if (Src->hasOneUse()) {
1229 Constant *ShAmt = GetNewShAmt(AWidth);
1230 Value *Shift = Builder.CreateAShr(LHS: A, RHS: ShAmt, Name: "", isExact: IsExact);
1231 return CastInst::CreateIntegerCast(S: Shift, Ty: DestTy, isSigned: true);
1232 }
1233 }
1234 // TODO: Mask high bits with 'and'.
1235 }
1236
1237 if (Instruction *I = narrowBinOp(Trunc))
1238 return I;
1239
1240 if (Instruction *I = shrinkSplatShuffle(Trunc, Builder))
1241 return I;
1242
1243 if (Instruction *I = shrinkInsertElt(Trunc, Builder))
1244 return I;
1245
1246 if (Src->hasOneUse() &&
1247 (isa<VectorType>(Val: SrcTy) || shouldChangeType(From: SrcTy, To: DestTy))) {
1248 // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
1249 // dest type is native and cst < dest size.
1250 if (match(V: Src, P: m_Shl(L: m_Value(V&: A), R: m_Constant(C))) &&
1251 !match(V: A, P: m_Shr(L: m_Value(), R: m_Constant()))) {
1252 // Skip shifts of shift by constants. It undoes a combine in
1253 // FoldShiftByConstant and is the extend in reg pattern.
1254 APInt Threshold = APInt(C->getType()->getScalarSizeInBits(), DestWidth);
1255 if (match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::ICMP_ULT, Threshold))) {
1256 // If neither the wide shift nor the truncate wrap, propagate the wrap
1257 // flags on the new truncate and shift.
1258 auto *WideShl = cast<OverflowingBinaryOperator>(Val: Src);
1259 bool NUW = Trunc.hasNoUnsignedWrap() && WideShl->hasNoUnsignedWrap();
1260 bool NSW = Trunc.hasNoSignedWrap() && WideShl->hasNoSignedWrap();
1261 Value *NewTrunc = Builder.CreateTrunc(V: A, DestTy, Name: A->getName() + ".tr",
1262 /*IsNUW=*/NUW, /*IsNSW=*/NSW);
1263 auto *NewShl = BinaryOperator::Create(
1264 Op: Instruction::Shl, S1: NewTrunc, S2: ConstantExpr::getTrunc(C, Ty: DestTy));
1265 NewShl->setHasNoUnsignedWrap(NUW);
1266 NewShl->setHasNoSignedWrap(NSW);
1267 return NewShl;
1268 }
1269 }
1270 }
1271
1272 // trunc (select(icmp_ult(A, DestTy_umax+1), A, sext(icmp_sgt(A, 0)))) -->
1273 // trunc (smin(smax(0, A), DestTy_umax))
1274 // Also handle the inverted form:
1275 // trunc (select(icmp_ugt(A, DestTy_umax), sext(icmp_sgt(A, 0)), A))
1276 CmpPredicate Pred;
1277 const APInt *CmpC;
1278 Value *TVal, *FVal;
1279 if (SrcTy->isIntegerTy() && isPowerOf2_64(Value: SrcWidth) &&
1280 isPowerOf2_64(Value: DestWidth) &&
1281 match(V: Src,
1282 P: m_OneUse(SubPattern: m_Select(C: m_OneUse(SubPattern: m_ICmp(Pred, L: m_Value(V&: A), R: m_APInt(Res&: CmpC))),
1283 L: m_Value(V&: TVal), R: m_Value(V&: FVal))))) {
1284 APInt TruncatedMax = APInt::getLowBitsSet(numBits: SrcWidth, loBitsSet: DestWidth);
1285 Value *SExtVal = nullptr;
1286 // Check the select arm first so that A is known to have type SrcTy.
1287 if (Pred == ICmpInst::ICMP_ULT && TVal == A && *CmpC == TruncatedMax + 1)
1288 SExtVal = FVal;
1289 else if (Pred == ICmpInst::ICMP_UGT && FVal == A && *CmpC == TruncatedMax)
1290 SExtVal = TVal;
1291 if (SExtVal &&
1292 match(V: SExtVal, P: m_OneUse(SubPattern: m_SExt(Op: m_OneUse(SubPattern: m_SpecificICmp(
1293 MatchPred: ICmpInst::ICMP_SGT, L: m_Specific(V: A), R: m_Zero())))))) {
1294 Value *SMax = Builder.CreateIntrinsic(ID: Intrinsic::smax, OverloadTypes: {SrcTy},
1295 Args: {ConstantInt::get(Ty: SrcTy, V: 0), A});
1296 Value *SMin = Builder.CreateIntrinsic(
1297 ID: Intrinsic::smin, OverloadTypes: {SrcTy},
1298 Args: {SMax, ConstantInt::get(Ty: SrcTy, V: TruncatedMax)});
1299 return new TruncInst(SMin, DestTy);
1300 }
1301 }
1302
1303 if (Instruction *I = foldVecTruncToExtElt(Trunc, IC&: *this))
1304 return I;
1305
1306 if (Instruction *I = foldVecExtTruncToExtElt(Trunc, IC&: *this))
1307 return I;
1308
1309 // trunc (ctlz_i32(zext(A), B) --> add(ctlz_i16(A, B), C)
1310 if (match(V: Src, P: m_OneUse(SubPattern: m_Ctlz(Op0: m_ZExt(Op: m_Value(V&: A)), Op1: m_Value(V&: B))))) {
1311 unsigned AWidth = A->getType()->getScalarSizeInBits();
1312 if (AWidth == DestWidth && AWidth > Log2_32(Value: SrcWidth)) {
1313 Value *WidthDiff = ConstantInt::get(Ty: A->getType(), V: SrcWidth - AWidth);
1314 Value *NarrowCtlz =
1315 Builder.CreateIntrinsic(ID: Intrinsic::ctlz, OverloadTypes: {Trunc.getType()}, Args: {A, B});
1316 return BinaryOperator::CreateAdd(V1: NarrowCtlz, V2: WidthDiff);
1317 }
1318 }
1319
1320 if (match(V: Src, P: m_VScale())) {
1321 if (Trunc.getFunction() &&
1322 Trunc.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1323 Attribute Attr =
1324 Trunc.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1325 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
1326 if (Log2_32(Value: *MaxVScale) < DestWidth)
1327 return replaceInstUsesWith(I&: Trunc, V: Builder.CreateVScale(Ty: DestTy));
1328 }
1329 }
1330
1331 // trunc(scmp(x, y)) -> scmp(x, y) with a narrower result type.
1332 // trunc(ucmp(x, y)) -> ucmp(x, y) with a narrower result type.
1333 // scmp/ucmp produce only -1, 0, or 1, so any result type with at least 2
1334 // bits can represent every possible value and the truncation is lossless.
1335 if (DestWidth >= 2)
1336 if (auto *CI = dyn_cast<CmpIntrinsic>(Val: Src); CI && CI->hasOneUse())
1337 return replaceInstUsesWith(
1338 I&: Trunc, V: Builder.CreateIntrinsic(RetTy: DestTy, ID: CI->getIntrinsicID(),
1339 Args: {CI->getLHS(), CI->getRHS()}));
1340
1341 if (DestWidth == 1 &&
1342 (Trunc.hasNoUnsignedWrap() || Trunc.hasNoSignedWrap()) &&
1343 isKnownNonZero(V: Src, Q: SQ.getWithInstruction(I: &Trunc)))
1344 return replaceInstUsesWith(I&: Trunc, V: ConstantInt::getTrue(Ty: DestTy));
1345
1346 bool Changed = false;
1347 if (!Trunc.hasNoSignedWrap() &&
1348 ComputeMaxSignificantBits(Op: Src, CtxI: &Trunc) <= DestWidth) {
1349 Trunc.setHasNoSignedWrap(true);
1350 Changed = true;
1351 }
1352 if (!Trunc.hasNoUnsignedWrap() &&
1353 MaskedValueIsZero(V: Src, Mask: APInt::getBitsSetFrom(numBits: SrcWidth, loBit: DestWidth),
1354 CtxI: &Trunc)) {
1355 Trunc.setHasNoUnsignedWrap(true);
1356 Changed = true;
1357 }
1358
1359 const APInt *C1;
1360 Value *V1;
1361 // OP = { lshr, ashr }
1362 // trunc ( OP i8 C1, V1) to i1 -> icmp eq V1, log_2(C1) iff C1 is power of 2
1363 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_Power2(V&: C1), R: m_Value(V&: V1)))) {
1364 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1365 return new ICmpInst(ICmpInst::ICMP_EQ, V1, Right);
1366 }
1367
1368 // OP = { lshr, ashr }
1369 // trunc ( OP i8 C1, V1) to i1 -> icmp ult V1, log_2(C1 + 1) iff (C1 + 1) is
1370 // power of 2
1371 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_LowBitMask(V&: C1), R: m_Value(V&: V1)))) {
1372 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_one());
1373 return new ICmpInst(ICmpInst::ICMP_ULT, V1, Right);
1374 }
1375
1376 // OP = { lshr, ashr }
1377 // trunc ( OP i8 C1, V1) to i1 -> icmp ugt V1, cttz(C1) - 1 iff (C1) is
1378 // negative power of 2
1379 if (DestWidth == 1 && match(V: Src, P: m_Shr(L: m_NegatedPower2(V&: C1), R: m_Value(V&: V1)))) {
1380 Value *Right = ConstantInt::get(Ty: V1->getType(), V: C1->countr_zero());
1381 return new ICmpInst(ICmpInst::ICMP_UGE, V1, Right);
1382 }
1383
1384 return Changed ? &Trunc : nullptr;
1385}
1386
1387Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp,
1388 ZExtInst &Zext) {
1389 // If we are just checking for a icmp eq of a single bit and zext'ing it
1390 // to an integer, then shift the bit to the appropriate place and then
1391 // cast to integer to avoid the comparison.
1392
1393 // FIXME: This set of transforms does not check for extra uses and/or creates
1394 // an extra instruction (an optional final cast is not included
1395 // in the transform comments). We may also want to favor icmp over
1396 // shifts in cases of equal instructions because icmp has better
1397 // analysis in general (invert the transform).
1398
1399 const APInt *Op1CV;
1400 if (match(V: Cmp->getOperand(i_nocapture: 1), P: m_APInt(Res&: Op1CV))) {
1401
1402 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
1403 if (Cmp->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isZero()) {
1404 Value *In = Cmp->getOperand(i_nocapture: 0);
1405 Value *Sh = ConstantInt::get(Ty: In->getType(),
1406 V: In->getType()->getScalarSizeInBits() - 1);
1407 In = Builder.CreateLShr(LHS: In, RHS: Sh, Name: In->getName() + ".lobit");
1408 if (In->getType() != Zext.getType())
1409 In = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false /*ZExt*/);
1410
1411 return replaceInstUsesWith(I&: Zext, V: In);
1412 }
1413
1414 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
1415 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
1416 // zext (X != 0) to i32 --> X iff X has only the low bit set.
1417 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
1418
1419 if (Op1CV->isZero() && Cmp->isEquality()) {
1420 // Exactly 1 possible 1? But not the high-bit because that is
1421 // canonicalized to this form.
1422 KnownBits Known = computeKnownBits(V: Cmp->getOperand(i_nocapture: 0), CtxI: &Zext);
1423 APInt KnownZeroMask(~Known.Zero);
1424 uint32_t ShAmt = KnownZeroMask.logBase2();
1425 bool IsExpectShAmt = KnownZeroMask.isPowerOf2() &&
1426 (Zext.getType()->getScalarSizeInBits() != ShAmt + 1);
1427 if (IsExpectShAmt &&
1428 (Cmp->getOperand(i_nocapture: 0)->getType() == Zext.getType() ||
1429 Cmp->getPredicate() == ICmpInst::ICMP_NE || ShAmt == 0)) {
1430 Value *In = Cmp->getOperand(i_nocapture: 0);
1431 if (ShAmt) {
1432 // Perform a logical shr by shiftamt.
1433 // Insert the shift to put the result in the low bit.
1434 In = Builder.CreateLShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: ShAmt),
1435 Name: In->getName() + ".lobit");
1436 }
1437
1438 // Toggle the low bit for "X == 0".
1439 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1440 In = Builder.CreateXor(LHS: In, RHS: ConstantInt::get(Ty: In->getType(), V: 1));
1441
1442 if (Zext.getType() == In->getType())
1443 return replaceInstUsesWith(I&: Zext, V: In);
1444
1445 Value *IntCast = Builder.CreateIntCast(V: In, DestTy: Zext.getType(), isSigned: false);
1446 return replaceInstUsesWith(I&: Zext, V: IntCast);
1447 }
1448 }
1449 }
1450
1451 if (Cmp->isEquality()) {
1452 // Test if a bit is clear/set using a shifted-one mask:
1453 // zext (icmp eq (and X, (1 << ShAmt)), 0) --> and (lshr (not X), ShAmt), 1
1454 // zext (icmp ne (and X, (1 << ShAmt)), 0) --> and (lshr X, ShAmt), 1
1455 Value *X, *ShAmt;
1456 if (Cmp->hasOneUse() && match(V: Cmp->getOperand(i_nocapture: 1), P: m_ZeroInt()) &&
1457 match(V: Cmp->getOperand(i_nocapture: 0),
1458 P: m_OneUse(SubPattern: m_c_And(L: m_Shl(L: m_One(), R: m_Value(V&: ShAmt)), R: m_Value(V&: X))))) {
1459 auto *And = cast<BinaryOperator>(Val: Cmp->getOperand(i_nocapture: 0));
1460 Value *Shift = And->getOperand(i_nocapture: X == And->getOperand(i_nocapture: 0) ? 1 : 0);
1461 if (Zext.getType() == And->getType() ||
1462 Cmp->getPredicate() != ICmpInst::ICMP_EQ || Shift->hasOneUse()) {
1463 if (Cmp->getPredicate() == ICmpInst::ICMP_EQ)
1464 X = Builder.CreateNot(V: X);
1465 Value *Lshr = Builder.CreateLShr(LHS: X, RHS: ShAmt);
1466 Value *And1 =
1467 Builder.CreateAnd(LHS: Lshr, RHS: ConstantInt::get(Ty: X->getType(), V: 1));
1468 return replaceInstUsesWith(
1469 I&: Zext, V: Builder.CreateZExtOrTrunc(V: And1, DestTy: Zext.getType()));
1470 }
1471 }
1472 }
1473
1474 return nullptr;
1475}
1476
1477/// Determine if the specified value can be computed in the specified wider type
1478/// and produce the same low bits. If not, return false.
1479///
1480/// If this function returns true, it can also return a non-zero number of bits
1481/// (in BitsToClear) which indicates that the value it computes is correct for
1482/// the zero extend, but that the additional BitsToClear bits need to be zero'd
1483/// out. For example, to promote something like:
1484///
1485/// %B = trunc i64 %A to i32
1486/// %C = lshr i32 %B, 8
1487/// %E = zext i32 %C to i64
1488///
1489/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
1490/// set to 8 to indicate that the promoted value needs to have bits 24-31
1491/// cleared in addition to bits 32-63. Since an 'and' will be generated to
1492/// clear the top bits anyway, doing this has no extra cost.
1493///
1494/// This function works on both vectors and scalars.
1495bool TypeEvaluationHelper::canEvaluateZExtd(Value *V, Type *Ty,
1496 unsigned &BitsToClear,
1497 InstCombinerImpl &IC,
1498 Instruction *CtxI) {
1499 TypeEvaluationHelper TYH(IC.CLOpts.max_type_eval_depth);
1500 return TYH.canEvaluateZExtdImpl(V, Ty, BitsToClear, IC, CtxI);
1501}
1502bool TypeEvaluationHelper::canEvaluateZExtdImpl(Value *V, Type *Ty,
1503 unsigned &BitsToClear,
1504 InstCombinerImpl &IC,
1505 Instruction *CtxI) {
1506 BitsToClear = 0;
1507 if (Depth >= MaxTypeEvalDepth)
1508 return false;
1509
1510 if (canAlwaysEvaluateInType(V, Ty))
1511 return true;
1512 // We stick to the one-user limit for the ZExt transform due to the fact
1513 // that this predicate returns two values: predicate result and BitsToClear.
1514 if (canNotEvaluateInType(V, Ty))
1515 return false;
1516
1517 // canEvaluateZExtd does not go through canEvaluate (it also returns
1518 // BitsToClear), so it has to track the depth itself.
1519 SaveAndRestore RestoreDepth(Depth, Depth + 1);
1520 auto *I = cast<Instruction>(Val: V);
1521 unsigned Tmp;
1522 switch (I->getOpcode()) {
1523 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
1524 case Instruction::SExt: // zext(sext(x)) -> sext(x).
1525 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
1526 return true;
1527 case Instruction::And:
1528 case Instruction::Or:
1529 case Instruction::Xor:
1530 case Instruction::Add:
1531 case Instruction::Sub:
1532 case Instruction::Mul:
1533 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CtxI) ||
1534 !canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CtxI))
1535 return false;
1536 // These can all be promoted if neither operand has 'bits to clear'.
1537 if (BitsToClear == 0 && Tmp == 0)
1538 return true;
1539
1540 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1541 // other side, BitsToClear is ok.
1542 if (Tmp == 0 && I->isBitwiseLogicOp()) {
1543 // We use MaskedValueIsZero here for generality, but the case we care
1544 // about the most is constant RHS.
1545 unsigned VSize = V->getType()->getScalarSizeInBits();
1546 if (IC.MaskedValueIsZero(V: I->getOperand(i: 1),
1547 Mask: APInt::getHighBitsSet(numBits: VSize, hiBitsSet: BitsToClear),
1548 CtxI)) {
1549 // If this is an And instruction and all of the BitsToClear are
1550 // known to be zero we can reset BitsToClear.
1551 if (I->getOpcode() == Instruction::And)
1552 BitsToClear = 0;
1553 return true;
1554 }
1555 }
1556
1557 // Otherwise, we don't know how to analyze this BitsToClear case yet.
1558 return false;
1559
1560 case Instruction::Shl: {
1561 // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1562 // upper bits we can reduce BitsToClear by the shift amount.
1563 uint64_t ShiftAmt;
1564 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1565 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CtxI))
1566 return false;
1567 BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1568 return true;
1569 }
1570 return false;
1571 }
1572 case Instruction::LShr: {
1573 // We can promote lshr(x, cst) if we can promote x. This requires the
1574 // ultimate 'and' to clear out the high zero bits we're clearing out though.
1575 uint64_t ShiftAmt;
1576 if (match(V: I->getOperand(i: 1), P: m_ConstantInt(V&: ShiftAmt))) {
1577 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 0), Ty, BitsToClear, IC, CtxI))
1578 return false;
1579 BitsToClear += ShiftAmt;
1580 if (BitsToClear > V->getType()->getScalarSizeInBits())
1581 BitsToClear = V->getType()->getScalarSizeInBits();
1582 return true;
1583 }
1584 // Cannot promote variable LSHR.
1585 return false;
1586 }
1587 case Instruction::Select:
1588 if (!canEvaluateZExtdImpl(V: I->getOperand(i: 1), Ty, BitsToClear&: Tmp, IC, CtxI) ||
1589 !canEvaluateZExtdImpl(V: I->getOperand(i: 2), Ty, BitsToClear, IC, CtxI) ||
1590 // TODO: If important, we could handle the case when the BitsToClear are
1591 // known zero in the disagreeing side.
1592 Tmp != BitsToClear)
1593 return false;
1594 return true;
1595
1596 case Instruction::PHI: {
1597 // We can change a phi if we can change all operands. Note that we never
1598 // get into trouble with cyclic PHIs here because we only consider
1599 // instructions with a single use.
1600 PHINode *PN = cast<PHINode>(Val: I);
1601 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i: 0), Ty, BitsToClear, IC,
1602 CtxI))
1603 return false;
1604 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
1605 if (!canEvaluateZExtdImpl(V: PN->getIncomingValue(i), Ty, BitsToClear&: Tmp, IC, CtxI) ||
1606 // TODO: If important, we could handle the case when the BitsToClear
1607 // are known zero in the disagreeing input.
1608 Tmp != BitsToClear)
1609 return false;
1610 return true;
1611 }
1612 case Instruction::Call:
1613 // llvm.vscale() can always be executed in larger type, because the
1614 // value is automatically zero-extended.
1615 if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I))
1616 if (II->getIntrinsicID() == Intrinsic::vscale)
1617 return true;
1618 return false;
1619 default:
1620 // TODO: Can handle more cases here.
1621 return false;
1622 }
1623}
1624
1625Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
1626 // If this zero extend is only used by a truncate, let the truncate be
1627 // eliminated before we try to optimize this zext.
1628 if (Zext.hasOneUse() && isa<TruncInst>(Val: Zext.user_back()) &&
1629 !isa<Constant>(Val: Zext.getOperand(i_nocapture: 0)))
1630 return nullptr;
1631
1632 // If one of the common conversion will work, do it.
1633 if (Instruction *Result = commonCastTransforms(CI&: Zext))
1634 return Result;
1635
1636 if (auto *NewI = foldExtractionOfVectorDeinterleave(RootZExt&: Zext))
1637 return NewI;
1638
1639 Value *Src = Zext.getOperand(i_nocapture: 0);
1640 Type *SrcTy = Src->getType(), *DestTy = Zext.getType();
1641
1642 // zext nneg bool x -> 0
1643 if (SrcTy->isIntOrIntVectorTy(BitWidth: 1) && Zext.hasNonNeg())
1644 return replaceInstUsesWith(I&: Zext, V: Constant::getNullValue(Ty: Zext.getType()));
1645
1646 // zext nneg means Src is non-negative and we can treat this as an sext.
1647 // Evaluating as a signed type means that any constant operands will be
1648 // sign-extended instead of zero-extended, which means that, if the
1649 // expression tree contains only no-signed-wrap arithmetic, the sign bits in
1650 // the final result should be enough that we avoid having to clear the high
1651 // bits.
1652 bool EvaluateAsSigned =
1653 Zext.hasNonNeg() && TypeEvaluationHelper::canEvaluateSExtd(
1654 V: Src, Ty: DestTy, MaxTypeEvalDepth: CLOpts.max_type_eval_depth);
1655
1656 // Try to extend the entire expression tree to the wide destination type.
1657 unsigned BitsToClear = 0;
1658 if (shouldChangeType(From: SrcTy, To: DestTy) &&
1659 (EvaluateAsSigned || TypeEvaluationHelper::canEvaluateZExtd(
1660 V: Src, Ty: DestTy, BitsToClear, IC&: *this, CtxI: &Zext))) {
1661 assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1662 "Can't clear more bits than in SrcTy");
1663
1664 // Okay, we can transform this! Insert the new expression now.
1665 LLVM_DEBUG(
1666 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1667 " to avoid zero extend: "
1668 << Zext << '\n');
1669 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: EvaluateAsSigned);
1670 assert(Res->getType() == DestTy);
1671
1672 // Preserve debug values referring to Src if the zext is its last use.
1673 if (auto *SrcOp = dyn_cast<Instruction>(Val: Src))
1674 if (SrcOp->hasOneUse())
1675 replaceAllDbgUsesWith(From&: *SrcOp, To&: *Res, DomPoint&: Zext, DT);
1676
1677 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits() - BitsToClear;
1678 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1679
1680 // If the high bits are already filled with zeros, just replace this
1681 // cast with the result. If we've evaluated as a signed expressions then
1682 // instead check that the high bits are the sign bit, which we know is zero.
1683 if (EvaluateAsSigned
1684 ? (ComputeNumSignBits(Op: Res, CtxI: &Zext) > DestBitSize - SrcBitsKept)
1685 : MaskedValueIsZero(
1686 V: Res,
1687 Mask: APInt::getHighBitsSet(numBits: DestBitSize, hiBitsSet: DestBitSize - SrcBitsKept),
1688 CtxI: &Zext))
1689 return replaceInstUsesWith(I&: Zext, V: Res);
1690
1691 // We need to emit an AND to clear the high bits.
1692 Constant *C = ConstantInt::get(Ty: Res->getType(),
1693 V: APInt::getLowBitsSet(numBits: DestBitSize, loBitsSet: SrcBitsKept));
1694 return BinaryOperator::CreateAnd(V1: Res, V2: C);
1695 }
1696
1697 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1698 // types and if the sizes are just right we can convert this into a logical
1699 // 'and' which will be much cheaper than the pair of casts.
1700 if (auto *CSrc = dyn_cast<TruncInst>(Val: Src)) { // A->B->C cast
1701 // TODO: Subsume this into EvaluateInDifferentType.
1702
1703 // Get the sizes of the types involved. We know that the intermediate type
1704 // will be smaller than A or C, but don't know the relation between A and C.
1705 Value *A = CSrc->getOperand(i_nocapture: 0);
1706 unsigned SrcSize = A->getType()->getScalarSizeInBits();
1707 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1708 unsigned DstSize = DestTy->getScalarSizeInBits();
1709 // If we're actually extending zero bits, then if
1710 // SrcSize < DstSize: zext(a & mask)
1711 // SrcSize == DstSize: a & mask
1712 // SrcSize > DstSize: trunc(a) & mask
1713 if (SrcSize < DstSize) {
1714 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1715 Constant *AndConst = ConstantInt::get(Ty: A->getType(), V: AndValue);
1716 Value *And = Builder.CreateAnd(LHS: A, RHS: AndConst, Name: CSrc->getName() + ".mask");
1717 return new ZExtInst(And, DestTy);
1718 }
1719
1720 if (SrcSize == DstSize) {
1721 APInt AndValue(APInt::getLowBitsSet(numBits: SrcSize, loBitsSet: MidSize));
1722 return BinaryOperator::CreateAnd(V1: A, V2: ConstantInt::get(Ty: A->getType(),
1723 V: AndValue));
1724 }
1725 if (SrcSize > DstSize) {
1726 Value *Trunc = Builder.CreateTrunc(V: A, DestTy);
1727 APInt AndValue(APInt::getLowBitsSet(numBits: DstSize, loBitsSet: MidSize));
1728 return BinaryOperator::CreateAnd(V1: Trunc,
1729 V2: ConstantInt::get(Ty: Trunc->getType(),
1730 V: AndValue));
1731 }
1732 }
1733
1734 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
1735 return transformZExtICmp(Cmp, Zext);
1736
1737 Constant *C;
1738 Value *X;
1739 // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1740 Value *And;
1741 if (match(V: Src, P: m_OneUse(SubPattern: m_Xor(L: m_Value(V&: And), R: m_Constant(C)))) &&
1742 match(V: And, P: m_OneUse(SubPattern: m_And(L: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: X)),
1743 R: m_Specific(V: C))))) {
1744 Value *ZC = Builder.CreateZExt(V: C, DestTy);
1745 return BinaryOperator::CreateXor(V1: Builder.CreateAnd(LHS: X, RHS: ZC), V2: ZC);
1746 }
1747
1748 // zext(sub(0, trunc(X))) -> and(sub(0, X), mask)
1749 if (match(V: Src, P: m_Sub(L: m_Zero(), R: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: X))))) {
1750 APInt Mask = APInt::getLowBitsSet(numBits: DestTy->getScalarSizeInBits(),
1751 loBitsSet: SrcTy->getScalarSizeInBits());
1752 Value *Neg = Builder.CreateSub(LHS: ConstantInt::get(Ty: DestTy, V: 0), RHS: X);
1753 return BinaryOperator::CreateAnd(V1: Neg, V2: ConstantInt::get(Ty: DestTy, V: Mask));
1754 }
1755
1756 // If we are truncating, masking, and then zexting back to the original type,
1757 // that's just a mask. This is not handled by canEvaluateZextd if the
1758 // intermediate values have extra uses. This could be generalized further for
1759 // a non-constant mask operand.
1760 // zext (and (trunc X), C) --> and X, (zext C)
1761 if (match(V: Src, P: m_And(L: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: X)), R: m_Constant(C)))) {
1762 Value *ZextC = Builder.CreateZExt(V: C, DestTy);
1763 return BinaryOperator::CreateAnd(V1: X, V2: ZextC);
1764 }
1765
1766 Value *Y;
1767 if (match(V: Src, P: m_OneUse(SubPattern: m_c_BitwiseLogic(
1768 L: m_NUWTrunc(Op: m_SpecificType(RefTy: DestTy, V&: X)), R: m_Value(V&: Y))))) {
1769 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
1770 return BinaryOperator::Create(Op: cast<BinaryOperator>(Val: Src)->getOpcode(), S1: X,
1771 S2: ZextY);
1772 }
1773
1774 if (match(V: Src, P: m_VScale())) {
1775 if (Zext.getFunction() &&
1776 Zext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
1777 Attribute Attr =
1778 Zext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
1779 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
1780 unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
1781 if (Log2_32(Value: *MaxVScale) < TypeWidth)
1782 return replaceInstUsesWith(I&: Zext, V: Builder.CreateVScale(Ty: DestTy));
1783 }
1784 }
1785 }
1786
1787 if (!Zext.hasNonNeg()) {
1788 // If this zero extend is only used by a shift, add nneg flag.
1789 if (Zext.hasOneUse() &&
1790 SrcTy->getScalarSizeInBits() >
1791 Log2_64_Ceil(Value: DestTy->getScalarSizeInBits()) &&
1792 match(V: Zext.user_back(), P: m_Shift(L: m_Value(), R: m_Specific(V: &Zext)))) {
1793 Zext.setNonNeg();
1794 return &Zext;
1795 }
1796
1797 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Zext))) {
1798 Zext.setNonNeg();
1799 return &Zext;
1800 }
1801 }
1802
1803 return nullptr;
1804}
1805
1806/// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
1807Instruction *InstCombinerImpl::transformSExtICmp(ICmpInst *Cmp,
1808 SExtInst &Sext) {
1809 Value *Op0 = Cmp->getOperand(i_nocapture: 0), *Op1 = Cmp->getOperand(i_nocapture: 1);
1810 ICmpInst::Predicate Pred = Cmp->getPredicate();
1811
1812 // Don't bother if Op1 isn't of vector or integer type.
1813 if (!Op1->getType()->isIntOrIntVectorTy())
1814 return nullptr;
1815
1816 if (Pred == ICmpInst::ICMP_SLT && match(V: Op1, P: m_ZeroInt())) {
1817 // sext (x <s 0) --> ashr x, 31 (all ones if negative)
1818 Value *Sh = ConstantInt::get(Ty: Op0->getType(),
1819 V: Op0->getType()->getScalarSizeInBits() - 1);
1820 Value *In = Builder.CreateAShr(LHS: Op0, RHS: Sh, Name: Op0->getName() + ".lobit");
1821 if (In->getType() != Sext.getType())
1822 In = Builder.CreateIntCast(V: In, DestTy: Sext.getType(), isSigned: true /*SExt*/);
1823
1824 return replaceInstUsesWith(I&: Sext, V: In);
1825 }
1826
1827 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Val: Op1)) {
1828 // If we know that only one bit of the LHS of the icmp can be set and we
1829 // have an equality comparison with zero or a power of 2, we can transform
1830 // the icmp and sext into bitwise/integer operations.
1831 if (Cmp->hasOneUse() &&
1832 Cmp->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
1833 KnownBits Known = computeKnownBits(V: Op0, CtxI: &Sext);
1834
1835 APInt KnownZeroMask(~Known.Zero);
1836 if (KnownZeroMask.isPowerOf2()) {
1837 Value *In = Cmp->getOperand(i_nocapture: 0);
1838
1839 // If the icmp tests for a known zero bit we can constant fold it.
1840 if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1841 Value *V = Pred == ICmpInst::ICMP_NE ?
1842 ConstantInt::getAllOnesValue(Ty: Sext.getType()) :
1843 ConstantInt::getNullValue(Ty: Sext.getType());
1844 return replaceInstUsesWith(I&: Sext, V);
1845 }
1846
1847 if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1848 // sext ((x & 2^n) == 0) -> (x >> n) - 1
1849 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1850 unsigned ShiftAmt = KnownZeroMask.countr_zero();
1851 // Perform a right shift to place the desired bit in the LSB.
1852 if (ShiftAmt)
1853 In = Builder.CreateLShr(LHS: In,
1854 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1855
1856 // At this point "In" is either 1 or 0. Subtract 1 to turn
1857 // {1, 0} -> {0, -1}.
1858 In = Builder.CreateAdd(LHS: In,
1859 RHS: ConstantInt::getAllOnesValue(Ty: In->getType()),
1860 Name: "sext");
1861 } else {
1862 // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
1863 // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
1864 unsigned ShiftAmt = KnownZeroMask.countl_zero();
1865 // Perform a left shift to place the desired bit in the MSB.
1866 if (ShiftAmt)
1867 In = Builder.CreateShl(LHS: In,
1868 RHS: ConstantInt::get(Ty: In->getType(), V: ShiftAmt));
1869
1870 // Distribute the bit over the whole bit width.
1871 In = Builder.CreateAShr(LHS: In, RHS: ConstantInt::get(Ty: In->getType(),
1872 V: KnownZeroMask.getBitWidth() - 1), Name: "sext");
1873 }
1874
1875 if (Sext.getType() == In->getType())
1876 return replaceInstUsesWith(I&: Sext, V: In);
1877 return CastInst::CreateIntegerCast(S: In, Ty: Sext.getType(), isSigned: true/*SExt*/);
1878 }
1879 }
1880 }
1881
1882 return nullptr;
1883}
1884
1885/// Return true if we can take the specified value and return it as type Ty
1886/// without inserting any new casts and without changing the value of the common
1887/// low bits. This is used by code that tries to promote integer operations to
1888/// a wider types will allow us to eliminate the extension.
1889///
1890/// This function works on both vectors and scalars.
1891///
1892bool TypeEvaluationHelper::canEvaluateSExtd(Value *V, Type *Ty,
1893 unsigned MaxTypeEvalDepth) {
1894 TypeEvaluationHelper TYH(MaxTypeEvalDepth);
1895 return TYH.canEvaluateSExtdImpl(V, Ty) && TYH.allPendingVisited();
1896}
1897
1898bool TypeEvaluationHelper::canEvaluateSExtdImpl(Value *V, Type *Ty) {
1899 return canEvaluate(V, Ty, Pred: [this](Value *V, Type *Ty) {
1900 return canEvaluateSExtdPred(V, Ty);
1901 });
1902}
1903
1904bool TypeEvaluationHelper::canEvaluateSExtdPred(Value *V, Type *Ty) {
1905 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
1906 "Can't sign extend type to a smaller type");
1907
1908 auto *I = cast<Instruction>(Val: V);
1909 switch (I->getOpcode()) {
1910 case Instruction::SExt: // sext(sext(x)) -> sext(x)
1911 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1912 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1913 return true;
1914 case Instruction::And:
1915 case Instruction::Or:
1916 case Instruction::Xor:
1917 case Instruction::Add:
1918 case Instruction::Sub:
1919 case Instruction::Mul:
1920 // These operators can all arbitrarily be extended if their inputs can.
1921 return canEvaluateSExtdImpl(V: I->getOperand(i: 0), Ty) &&
1922 canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty);
1923
1924 // case Instruction::Shl: TODO
1925 // case Instruction::LShr: TODO
1926
1927 case Instruction::Select:
1928 return canEvaluateSExtdImpl(V: I->getOperand(i: 1), Ty) &&
1929 canEvaluateSExtdImpl(V: I->getOperand(i: 2), Ty);
1930
1931 case Instruction::PHI: {
1932 // We can change a phi if we can change all operands. Note that we never
1933 // get into trouble with cyclic PHIs here because canEvaluate handles use
1934 // chain loops.
1935 PHINode *PN = cast<PHINode>(Val: I);
1936 for (Value *IncValue : PN->incoming_values())
1937 if (!canEvaluateSExtdImpl(V: IncValue, Ty))
1938 return false;
1939 return true;
1940 }
1941 default:
1942 // TODO: Can handle more cases here.
1943 break;
1944 }
1945
1946 return false;
1947}
1948
1949Instruction *InstCombinerImpl::visitSExt(SExtInst &Sext) {
1950 // If this sign extend is only used by a truncate, let the truncate be
1951 // eliminated before we try to optimize this sext.
1952 if (Sext.hasOneUse() && isa<TruncInst>(Val: Sext.user_back()))
1953 return nullptr;
1954
1955 if (Instruction *I = commonCastTransforms(CI&: Sext))
1956 return I;
1957
1958 Value *Src = Sext.getOperand(i_nocapture: 0);
1959 Type *SrcTy = Src->getType(), *DestTy = Sext.getType();
1960 unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1961 unsigned DestBitSize = DestTy->getScalarSizeInBits();
1962
1963 // If the value being extended is zero or positive, use a zext instead.
1964 if (isKnownNonNegative(V: Src, SQ: SQ.getWithInstruction(I: &Sext))) {
1965 auto CI = CastInst::Create(Instruction::ZExt, S: Src, Ty: DestTy);
1966 CI->setNonNeg(true);
1967 return CI;
1968 }
1969
1970 Value *X;
1971 if (match(V: Src, P: m_Trunc(Op: m_Value(V&: X)))) {
1972 // If the input has more sign bits than bits truncated, then convert
1973 // directly to final type.
1974 unsigned XBitSize = X->getType()->getScalarSizeInBits();
1975 unsigned TruncatedBits = XBitSize - SrcBitSize;
1976 bool HasNSW = cast<TruncInst>(Val: Src)->hasNoSignedWrap();
1977 if (HasNSW || (ComputeNumSignBits(Op: X, CtxI: &Sext) > TruncatedBits)) {
1978 auto *Res = CastInst::CreateIntegerCast(S: X, Ty: DestTy, /* isSigned */ true);
1979 if (auto *ResTrunc = dyn_cast<TruncInst>(Val: Res); ResTrunc && HasNSW)
1980 ResTrunc->setHasNoSignedWrap(true);
1981 return Res;
1982 }
1983
1984 // If we are replacing shifted-in high zero bits with sign bits, convert
1985 // the logic shift to arithmetic shift and eliminate the cast to
1986 // intermediate type:
1987 // sext (trunc (lshr Y, C)) --> sext/trunc (ashr Y, C)
1988 // where C <= truncatedbits && signbits(Y) + C > truncatedbits
1989 Value *Y;
1990 const APInt *C;
1991 if (Src->hasOneUse() &&
1992 match(V: X, P: m_LShr(L: m_Value(V&: Y), R: m_APIntAllowPoison(Res&: C))) &&
1993 C->ule(RHS: TruncatedBits) &&
1994 (*C == TruncatedBits ||
1995 ComputeNumSignBits(Op: Y, CtxI: &Sext) + C->getZExtValue() > TruncatedBits)) {
1996 Value *Ashr = Builder.CreateAShr(LHS: Y, RHS: C->getZExtValue());
1997 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
1998 }
1999
2000 // If input is a trunc from the destination type, then convert into shifts.
2001 if (Src->hasOneUse() && X->getType() == DestTy) {
2002 // sext (trunc X) --> ashr (shl X, C), C
2003 Constant *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
2004 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShAmt), V2: ShAmt);
2005 }
2006 }
2007
2008 // Try to extend the entire expression tree to the wide destination type.
2009 bool ShouldExtendExpression = true;
2010 Value *TruncSrc = nullptr;
2011 // It is not desirable to extend expression in the trunc + sext pattern when
2012 // destination type is narrower than original (pre-trunc) type.
2013 if (match(V: Src, P: m_Trunc(Op: m_Value(V&: TruncSrc))))
2014 if (TruncSrc->getType()->getScalarSizeInBits() > DestBitSize)
2015 ShouldExtendExpression = false;
2016 if (ShouldExtendExpression && shouldChangeType(From: SrcTy, To: DestTy) &&
2017 TypeEvaluationHelper::canEvaluateSExtd(V: Src, Ty: DestTy,
2018 MaxTypeEvalDepth: CLOpts.max_type_eval_depth)) {
2019 // Okay, we can transform this! Insert the new expression now.
2020 LLVM_DEBUG(
2021 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
2022 " to avoid sign extend: "
2023 << Sext << '\n');
2024 Value *Res = EvaluateInDifferentType(V: Src, Ty: DestTy, isSigned: true);
2025 assert(Res->getType() == DestTy);
2026
2027 // If the high bits are already filled with sign bit, just replace this
2028 // cast with the result.
2029 if (ComputeNumSignBits(Op: Res, CtxI: &Sext) > DestBitSize - SrcBitSize)
2030 return replaceInstUsesWith(I&: Sext, V: Res);
2031
2032 // We need to emit a shl + ashr to do the sign extend.
2033 Value *ShAmt = ConstantInt::get(Ty: DestTy, V: DestBitSize - SrcBitSize);
2034 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: Res, RHS: ShAmt, Name: "sext"),
2035 V2: ShAmt);
2036 }
2037
2038 if (auto *Cmp = dyn_cast<ICmpInst>(Val: Src))
2039 return transformSExtICmp(Cmp, Sext);
2040
2041 // If the input is a shl/ashr pair of a same constant, then this is a sign
2042 // extension from a smaller value. If we could trust arbitrary bitwidth
2043 // integers, we could turn this into a truncate to the smaller bit and then
2044 // use a sext for the whole extension. Since we don't, look deeper and check
2045 // for a truncate. If the source and dest are the same type, eliminate the
2046 // trunc and extend and just do shifts. For example, turn:
2047 // %a = trunc i32 %i to i8
2048 // %b = shl i8 %a, C
2049 // %c = ashr i8 %b, C
2050 // %d = sext i8 %c to i32
2051 // into:
2052 // %a = shl i32 %i, 32-(8-C)
2053 // %d = ashr i32 %a, 32-(8-C)
2054 Value *A = nullptr;
2055 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
2056 Constant *BA = nullptr, *CA = nullptr;
2057 if (match(V: Src,
2058 P: m_AShr(L: m_Shl(L: m_Trunc(Op: m_SpecificType(RefTy: DestTy, V&: A)), R: m_Constant(C&: BA)),
2059 R: m_ImmConstant(C&: CA))) &&
2060 BA->isElementWiseEqual(Y: CA)) {
2061 Constant *WideCurrShAmt =
2062 ConstantFoldCastOperand(Opcode: Instruction::SExt, C: CA, DestTy, DL);
2063 assert(WideCurrShAmt && "Constant folding of ImmConstant cannot fail");
2064 Constant *NumLowbitsLeft = ConstantExpr::getSub(
2065 C1: ConstantInt::get(Ty: DestTy, V: SrcTy->getScalarSizeInBits()), C2: WideCurrShAmt);
2066 Constant *NewShAmt = ConstantExpr::getSub(
2067 C1: ConstantInt::get(Ty: DestTy, V: DestTy->getScalarSizeInBits()),
2068 C2: NumLowbitsLeft);
2069 NewShAmt =
2070 Constant::mergeUndefsWith(C: Constant::mergeUndefsWith(C: NewShAmt, Other: BA), Other: CA);
2071 A = Builder.CreateShl(LHS: A, RHS: NewShAmt, Name: Sext.getName());
2072 return BinaryOperator::CreateAShr(V1: A, V2: NewShAmt);
2073 }
2074
2075 // Splatting a bit of constant-index across a value:
2076 // sext (ashr (trunc iN X to iM), M-1) to iN --> ashr (shl X, N-M), N-1
2077 // If the dest type is different, use a cast (adjust use check).
2078 if (match(V: Src, P: m_OneUse(SubPattern: m_AShr(L: m_Trunc(Op: m_Value(V&: X)),
2079 R: m_SpecificInt(V: SrcBitSize - 1))))) {
2080 Type *XTy = X->getType();
2081 unsigned XBitSize = XTy->getScalarSizeInBits();
2082 Constant *ShlAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - SrcBitSize);
2083 Constant *AshrAmtC = ConstantInt::get(Ty: XTy, V: XBitSize - 1);
2084 if (XTy == DestTy)
2085 return BinaryOperator::CreateAShr(V1: Builder.CreateShl(LHS: X, RHS: ShlAmtC),
2086 V2: AshrAmtC);
2087 if (cast<BinaryOperator>(Val: Src)->getOperand(i_nocapture: 0)->hasOneUse()) {
2088 Value *Ashr = Builder.CreateAShr(LHS: Builder.CreateShl(LHS: X, RHS: ShlAmtC), RHS: AshrAmtC);
2089 return CastInst::CreateIntegerCast(S: Ashr, Ty: DestTy, /* isSigned */ true);
2090 }
2091 }
2092
2093 if (match(V: Src, P: m_VScale())) {
2094 if (Sext.getFunction() &&
2095 Sext.getFunction()->hasFnAttribute(Kind: Attribute::VScaleRange)) {
2096 Attribute Attr =
2097 Sext.getFunction()->getFnAttribute(Kind: Attribute::VScaleRange);
2098 if (std::optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
2099 if (Log2_32(Value: *MaxVScale) < (SrcBitSize - 1))
2100 return replaceInstUsesWith(I&: Sext, V: Builder.CreateVScale(Ty: DestTy));
2101 }
2102 }
2103
2104 // sext(scmp(x, y)) -> scmp(x, y) with a wider result type.
2105 // sext(ucmp(x, y)) -> ucmp(x, y) with a wider result type.
2106 // scmp/ucmp return only -1, 0, or 1, which sign-extend correctly to any
2107 // wider integer type, so we can sink the extension into the intrinsic.
2108 if (auto *CI = dyn_cast<CmpIntrinsic>(Val: Src); CI && CI->hasOneUse())
2109 return replaceInstUsesWith(
2110 I&: Sext, V: Builder.CreateIntrinsic(RetTy: DestTy, ID: CI->getIntrinsicID(),
2111 Args: {CI->getLHS(), CI->getRHS()}));
2112
2113 Value *Y;
2114 if (match(V: Src, P: m_OneUse(SubPattern: m_c_BitwiseLogic(
2115 L: m_NSWTrunc(Op: m_SpecificType(RefTy: DestTy, V&: X)), R: m_Value(V&: Y))))) {
2116 Value *SextY = Builder.CreateSExt(V: Y, DestTy);
2117 return BinaryOperator::Create(Op: cast<BinaryOperator>(Val: Src)->getOpcode(), S1: X,
2118 S2: SextY);
2119 }
2120
2121 return nullptr;
2122}
2123
2124/// Return a Constant* for the specified floating-point constant if it fits
2125/// in the specified FP type without changing its value.
2126static bool fitsInFPType(APFloat F, const fltSemantics &Sem) {
2127 bool losesInfo;
2128 (void)F.convert(ToSemantics: Sem, RM: APFloat::rmNearestTiesToEven, losesInfo: &losesInfo);
2129 return !losesInfo;
2130}
2131
2132static Type *shrinkFPConstant(LLVMContext &Ctx, const APFloat &F,
2133 bool PreferBFloat) {
2134 // See if the value can be truncated to bfloat and then reextended.
2135 if (PreferBFloat && fitsInFPType(F, Sem: APFloat::BFloat()))
2136 return Type::getBFloatTy(C&: Ctx);
2137 // See if the value can be truncated to half and then reextended.
2138 if (!PreferBFloat && fitsInFPType(F, Sem: APFloat::IEEEhalf()))
2139 return Type::getHalfTy(C&: Ctx);
2140 // See if the value can be truncated to float and then reextended.
2141 if (fitsInFPType(F, Sem: APFloat::IEEEsingle()))
2142 return Type::getFloatTy(C&: Ctx);
2143 if (&F.getSemantics() == &APFloat::IEEEdouble())
2144 return nullptr; // Won't shrink.
2145 // See if the value can be truncated to double and then reextended.
2146 if (fitsInFPType(F, Sem: APFloat::IEEEdouble()))
2147 return Type::getDoubleTy(C&: Ctx);
2148 // Don't try to shrink to various long double types.
2149 return nullptr;
2150}
2151
2152static Type *shrinkFPConstant(ConstantFP *CFP, bool PreferBFloat) {
2153 Type *Ty = CFP->getType();
2154 if (Ty->getScalarType()->isPPC_FP128Ty())
2155 return nullptr; // No constant folding of this.
2156
2157 Type *ShrinkTy =
2158 shrinkFPConstant(Ctx&: CFP->getContext(), F: CFP->getValueAPF(), PreferBFloat);
2159 if (ShrinkTy)
2160 if (auto *VecTy = dyn_cast<VectorType>(Val: Ty))
2161 ShrinkTy = VectorType::get(ElementType: ShrinkTy, Other: VecTy);
2162
2163 return ShrinkTy;
2164}
2165
2166// Determine if this is a vector of ConstantFPs and if so, return the minimal
2167// type we can safely truncate all elements to.
2168static Type *shrinkFPConstantVector(Value *V, bool PreferBFloat) {
2169 auto *CV = dyn_cast<Constant>(Val: V);
2170 auto *CVVTy = dyn_cast<FixedVectorType>(Val: V->getType());
2171 if (!CV || !CVVTy)
2172 return nullptr;
2173
2174 Type *MinType = nullptr;
2175
2176 unsigned NumElts = CVVTy->getNumElements();
2177
2178 // For fixed-width vectors we find the minimal type by looking
2179 // through the constant values of the vector.
2180 for (unsigned I = 0; I != NumElts; ++I) {
2181 if (match(V: CV->getAggregateElement(Elt: I), P: m_Poison()))
2182 continue;
2183
2184 auto *CFP = dyn_cast_or_null<ConstantFP>(Val: CV->getAggregateElement(Elt: I));
2185 if (!CFP)
2186 return nullptr;
2187
2188 Type *T = shrinkFPConstant(CFP, PreferBFloat);
2189 if (!T)
2190 return nullptr;
2191
2192 // If we haven't found a type yet or this type has a larger mantissa than
2193 // our previous type, this is our new minimal type.
2194 if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
2195 MinType = T;
2196 }
2197
2198 // Make a vector type from the minimal type.
2199 return MinType ? FixedVectorType::get(ElementType: MinType, NumElts) : nullptr;
2200}
2201
2202/// Find the minimum FP type we can safely truncate to.
2203static Type *getMinimumFPType(Value *V, Type *PreferredTy, InstCombiner &IC) {
2204 if (auto *FPExt = dyn_cast<FPExtInst>(Val: V))
2205 return FPExt->getOperand(i_nocapture: 0)->getType();
2206
2207 Value *Src;
2208 if (match(V, P: m_IToFP(Op: m_Value(V&: Src))) &&
2209 IC.canBeCastedExactlyIntToFP(V: Src, FPTy: PreferredTy, IsSigned: isa<SIToFPInst>(Val: V),
2210 CtxI: cast<Instruction>(Val: V)))
2211 return PreferredTy;
2212
2213 bool PreferBFloat = PreferredTy->getScalarType()->isBFloatTy();
2214 // If this value is a constant, return the constant in the smallest FP type
2215 // that can accurately represent it. This allows us to turn
2216 // (float)((double)X+2.0) into x+2.0f.
2217 if (auto *CFP = dyn_cast<ConstantFP>(Val: V))
2218 if (Type *T = shrinkFPConstant(CFP, PreferBFloat))
2219 return T;
2220
2221 // Try to shrink scalable and fixed splat vectors.
2222 if (auto *FPC = dyn_cast<Constant>(Val: V))
2223 if (auto *VTy = dyn_cast<VectorType>(Val: V->getType()))
2224 if (auto *Splat = dyn_cast_or_null<ConstantFP>(Val: FPC->getSplatValue()))
2225 if (Type *T = shrinkFPConstant(CFP: Splat, PreferBFloat))
2226 return VectorType::get(ElementType: T, Other: VTy);
2227
2228 // Try to shrink a vector of FP constants. This returns nullptr on scalable
2229 // vectors
2230 if (Type *T = shrinkFPConstantVector(V, PreferBFloat))
2231 return T;
2232
2233 return V->getType();
2234}
2235
2236bool InstCombiner::canBeCastedExactlyIntToFP(Value *V, Type *FPTy,
2237 bool IsSigned,
2238 const Instruction *CtxI) const {
2239 Type *SrcTy = V->getType();
2240 assert(SrcTy->isIntOrIntVectorTy() && "Expected an integer type");
2241 int SrcSize = (int)SrcTy->getScalarSizeInBits() - IsSigned;
2242 int DestNumSigBits = FPTy->getFPMantissaWidth();
2243
2244 // Easy case - if the source integer type has less bits than the FP mantissa,
2245 // then the cast must be exact.
2246 if (SrcSize <= DestNumSigBits)
2247 return true;
2248
2249 // Cast from FP to integer and back to FP is independent of the intermediate
2250 // integer width because of poison on overflow.
2251 Value *F;
2252 if (match(V, P: m_FPToI(Op: m_Value(V&: F)))) {
2253 // If this is uitofp (fptosi F), the source needs an extra bit to avoid
2254 // potential rounding of negative FP input values.
2255 int SrcNumSigBits = F->getType()->getFPMantissaWidth();
2256 if (!IsSigned && match(V, P: m_FPToSI(Op: m_Value())))
2257 SrcNumSigBits++;
2258
2259 // [su]itofp (fpto[su]i F) --> exact if the source type has less or equal
2260 // significant bits than the destination (and make sure neither type is
2261 // weird -- ppc_fp128).
2262 if (SrcNumSigBits > 0 && DestNumSigBits > 0 &&
2263 SrcNumSigBits <= DestNumSigBits)
2264 return true;
2265 }
2266
2267 // Try harder to find if the source integer type has less significant bits.
2268 // Compute number of sign bits or determine trailing zeros.
2269 KnownBits SrcKnown = computeKnownBits(V, CtxI);
2270 int SigBits = (int)SrcTy->getScalarSizeInBits() -
2271 SrcKnown.countMinLeadingZeros() -
2272 SrcKnown.countMinTrailingZeros();
2273 if (SigBits <= DestNumSigBits)
2274 return true;
2275
2276 // For sitofp, the sign maps to the FP sign bit, so only magnitude bits
2277 // (BitWidth - NumSignBits) consume mantissa.
2278 if (IsSigned) {
2279 SigBits = (int)SrcTy->getScalarSizeInBits() - ComputeNumSignBits(Op: V, CtxI);
2280 if (SigBits <= DestNumSigBits)
2281 return true;
2282 }
2283
2284 return false;
2285}
2286
2287bool InstCombiner::isKnownExactCastIntToFP(CastInst &I) const {
2288 CastInst::CastOps Opcode = I.getOpcode();
2289 assert((Opcode == CastInst::SIToFP || Opcode == CastInst::UIToFP) &&
2290 "Unexpected cast");
2291 Value *Src = I.getOperand(i_nocapture: 0);
2292 Type *FPTy = I.getType();
2293 return canBeCastedExactlyIntToFP(V: Src, FPTy, IsSigned: Opcode == CastInst::SIToFP, CtxI: &I);
2294}
2295
2296Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {
2297 if (Instruction *I = commonCastTransforms(CI&: FPT))
2298 return I;
2299
2300 // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
2301 // simplify this expression to avoid one or more of the trunc/extend
2302 // operations if we can do so without changing the numerical results.
2303 //
2304 // The exact manner in which the widths of the operands interact to limit
2305 // what we can and cannot do safely varies from operation to operation, and
2306 // is explained below in the various case statements.
2307 Type *Ty = FPT.getType();
2308 auto *BO = dyn_cast<BinaryOperator>(Val: FPT.getOperand(i_nocapture: 0));
2309 if (BO && BO->hasOneUse()) {
2310 Type *LHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 0), PreferredTy: Ty, IC&: *this);
2311 Type *RHSMinType = getMinimumFPType(V: BO->getOperand(i_nocapture: 1), PreferredTy: Ty, IC&: *this);
2312 unsigned OpWidth = BO->getType()->getFPMantissaWidth();
2313 unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
2314 unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
2315 unsigned SrcWidth = std::max(a: LHSWidth, b: RHSWidth);
2316 unsigned DstWidth = Ty->getFPMantissaWidth();
2317
2318 // The operands must be convertible to the destination type without loss.
2319 // This is more than comparing the significand widths: the source type may
2320 // have a larger exponent range (e.g. bfloat has fewer significand bits than
2321 // half, but a much wider range).
2322 auto IsLosslesslyConvertibleToDst = [&](Type *SrcTy) {
2323 return APFloat::isLosslesslyConvertibleTo(
2324 From: SrcTy->getScalarType()->getFltSemantics(),
2325 To: Ty->getScalarType()->getFltSemantics(), /*IgnoreNaNs=*/true);
2326 };
2327 bool OperandsFitDst = IsLosslesslyConvertibleToDst(LHSMinType) &&
2328 IsLosslesslyConvertibleToDst(RHSMinType);
2329
2330 // Narrowing recomputes the binop in a smaller type, which can overflow to
2331 // inf where the wide op was finite. Therefore we can only keep ninf if
2332 // both the binop and the fptrunc have that flag.
2333 FastMathFlags NarrowFMF = BO->getFastMathFlags();
2334 NarrowFMF.setNoInfs(NarrowFMF.noInfs() && FPT.hasNoInfs());
2335
2336 switch (BO->getOpcode()) {
2337 default: break;
2338 case Instruction::FAdd:
2339 case Instruction::FSub:
2340 // For addition and subtraction, the infinitely precise result can
2341 // essentially be arbitrarily wide; proving that double rounding
2342 // will not occur because the result of OpI is exact (as we will for
2343 // FMul, for example) is hopeless. However, we *can* nonetheless
2344 // frequently know that double rounding cannot occur (or that it is
2345 // innocuous) by taking advantage of the specific structure of
2346 // infinitely-precise results that admit double rounding.
2347 //
2348 // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
2349 // to represent both sources, we can guarantee that the double
2350 // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
2351 // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
2352 // for proof of this fact).
2353 //
2354 // Note: Figueroa does not consider the case where DstFormat !=
2355 // SrcFormat. It's possible (likely even!) that this analysis
2356 // could be tightened for those cases, but they are rare (the main
2357 // case of interest here is (float)((double)float + float)).
2358 if (OpWidth >= 2 * DstWidth + 1 && OperandsFitDst) {
2359 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2360 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2361 Instruction *RI = BinaryOperator::Create(Op: BO->getOpcode(), S1: LHS, S2: RHS);
2362 RI->setFastMathFlags(NarrowFMF);
2363 return RI;
2364 }
2365 break;
2366 case Instruction::FMul:
2367 // For multiplication, the infinitely precise result has at most
2368 // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
2369 // that such a value can be exactly represented, then no double
2370 // rounding can possibly occur; we can safely perform the operation
2371 // in the destination format if it can represent both sources.
2372 if (OpWidth >= LHSWidth + RHSWidth && OperandsFitDst) {
2373 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2374 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2375 return BinaryOperator::CreateFMulFMF(V1: LHS, V2: RHS, FMF: NarrowFMF);
2376 }
2377 break;
2378 case Instruction::FDiv:
2379 // For division, we use again use the bound from Figueroa's
2380 // dissertation. I am entirely certain that this bound can be
2381 // tightened in the unbalanced operand case by an analysis based on
2382 // the diophantine rational approximation bound, but the well-known
2383 // condition used here is a good conservative first pass.
2384 // TODO: Tighten bound via rigorous analysis of the unbalanced case.
2385 if (OpWidth >= 2 * DstWidth && OperandsFitDst) {
2386 Value *LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: Ty);
2387 Value *RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: Ty);
2388 return BinaryOperator::CreateFDivFMF(V1: LHS, V2: RHS, FMF: NarrowFMF);
2389 }
2390 break;
2391 case Instruction::FRem: {
2392 // Remainder is straightforward. Remainder is always exact, so the
2393 // type of OpI doesn't enter into things at all. We simply evaluate
2394 // in whichever source type is larger, then convert to the
2395 // destination type.
2396 if (SrcWidth == OpWidth)
2397 break;
2398 Value *LHS, *RHS;
2399 if (LHSWidth == SrcWidth) {
2400 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: LHSMinType);
2401 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: LHSMinType);
2402 } else {
2403 LHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 0), DestTy: RHSMinType);
2404 RHS = Builder.CreateFPTrunc(V: BO->getOperand(i_nocapture: 1), DestTy: RHSMinType);
2405 }
2406
2407 Value *ExactResult = Builder.CreateFRemFMF(L: LHS, R: RHS, FMFSource: BO);
2408 return CastInst::CreateFPCast(S: ExactResult, Ty);
2409 }
2410 }
2411 }
2412
2413 // (fptrunc (fneg x)) -> (fneg (fptrunc x))
2414 Value *X;
2415 Instruction *Op = dyn_cast<Instruction>(Val: FPT.getOperand(i_nocapture: 0));
2416 if (Op && Op->hasOneUse()) {
2417 FastMathFlags FMF = FPT.getFastMathFlags();
2418 if (auto *FPMO = dyn_cast<FPMathOperator>(Val: Op))
2419 FMF &= FPMO->getFastMathFlags();
2420
2421 if (match(V: Op, P: m_FNeg(X: m_Value(V&: X)))) {
2422 Value *InnerTrunc = Builder.CreateFPTruncFMF(V: X, DestTy: Ty, FMFSource: FMF);
2423 Value *Neg = Builder.CreateFNegFMF(V: InnerTrunc, FMFSource: FMF);
2424 return replaceInstUsesWith(I&: FPT, V: Neg);
2425 }
2426
2427 // If we are truncating a select that has an extended operand, we can
2428 // narrow the other operand and do the select as a narrow op.
2429 Value *Cond, *X, *Y;
2430 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_FPExt(Op: m_SpecificType(RefTy: Ty, V&: X)),
2431 R: m_Value(V&: Y)))) {
2432 // fptrunc (select Cond, (fpext X), Y --> select Cond, X, (fptrunc Y)
2433 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2434 Value *Sel =
2435 Builder.CreateSelectFMF(C: Cond, True: X, False: NarrowY, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2436 return replaceInstUsesWith(I&: FPT, V: Sel);
2437 }
2438 if (match(V: Op, P: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: Y),
2439 R: m_FPExt(Op: m_SpecificType(RefTy: Ty, V&: X))))) {
2440 // fptrunc (select Cond, Y, (fpext X) --> select Cond, (fptrunc Y), X
2441 Value *NarrowY = Builder.CreateFPTruncFMF(V: Y, DestTy: Ty, FMFSource: FMF);
2442 Value *Sel =
2443 Builder.CreateSelectFMF(C: Cond, True: NarrowY, False: X, FMFSource: FMF, Name: "narrow.sel", MDFrom: Op);
2444 return replaceInstUsesWith(I&: FPT, V: Sel);
2445 }
2446 }
2447
2448 if (auto *II = dyn_cast<IntrinsicInst>(Val: FPT.getOperand(i_nocapture: 0))) {
2449 switch (II->getIntrinsicID()) {
2450 default: break;
2451 case Intrinsic::ceil:
2452 case Intrinsic::fabs:
2453 case Intrinsic::floor:
2454 case Intrinsic::nearbyint:
2455 case Intrinsic::rint:
2456 case Intrinsic::round:
2457 case Intrinsic::roundeven:
2458 case Intrinsic::trunc: {
2459 Value *Src = II->getArgOperand(i: 0);
2460 if (!Src->hasOneUse())
2461 break;
2462
2463 // Except for fabs, this transformation requires the input of the unary FP
2464 // operation to be itself an fpext from the type to which we're
2465 // truncating.
2466 if (II->getIntrinsicID() != Intrinsic::fabs) {
2467 FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Val: Src);
2468 if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
2469 break;
2470 }
2471
2472 // Do unary FP operation on smaller type.
2473 // (fptrunc (fabs x)) -> (fabs (fptrunc x))
2474 Value *InnerTrunc = Builder.CreateFPTrunc(V: Src, DestTy: Ty);
2475 Function *Overload = Intrinsic::getOrInsertDeclaration(
2476 M: FPT.getModule(), id: II->getIntrinsicID(), OverloadTys: Ty);
2477 SmallVector<OperandBundleDef, 1> OpBundles;
2478 II->getOperandBundlesAsDefs(Defs&: OpBundles);
2479 CallInst *NewCI =
2480 CallInst::Create(Func: Overload, Args: {InnerTrunc}, Bundles: OpBundles, NameStr: II->getName());
2481 // A normal value may be converted to an infinity. It means that we cannot
2482 // propagate ninf from the intrinsic. So we propagate FMF from fptrunc.
2483 NewCI->copyFastMathFlags(I: &FPT);
2484 return NewCI;
2485 }
2486 }
2487 }
2488
2489 if (Instruction *I = shrinkInsertElt(Trunc&: FPT, Builder))
2490 return I;
2491
2492 Value *Src = FPT.getOperand(i_nocapture: 0);
2493 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2494 auto *FPCast = cast<CastInst>(Val: Src);
2495 if (isKnownExactCastIntToFP(I&: *FPCast))
2496 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2497 }
2498
2499 return nullptr;
2500}
2501
2502Instruction *InstCombinerImpl::visitFPExt(CastInst &FPExt) {
2503 // If the source operand is a cast from integer to FP and known exact, then
2504 // cast the integer operand directly to the destination type.
2505 Type *Ty = FPExt.getType();
2506 Value *Src = FPExt.getOperand(i_nocapture: 0);
2507 if (isa<SIToFPInst>(Val: Src) || isa<UIToFPInst>(Val: Src)) {
2508 auto *FPCast = cast<CastInst>(Val: Src);
2509 if (isKnownExactCastIntToFP(I&: *FPCast))
2510 return CastInst::Create(FPCast->getOpcode(), S: FPCast->getOperand(i_nocapture: 0), Ty);
2511 }
2512
2513 return commonCastTransforms(CI&: FPExt);
2514}
2515
2516/// fpto{s/u}i[.sat]({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
2517/// This is safe if the intermediate type has enough bits in its mantissa to
2518/// accurately represent all values of X. For example, this won't work with
2519/// i64 -> float -> i64.
2520template <typename FPToIntTy>
2521Instruction *InstCombinerImpl::foldItoFPtoI(FPToIntTy &FI) {
2522 constexpr bool IsSaturating = std::is_same_v<FPToIntTy, IntrinsicInst>;
2523
2524 if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
2525 return nullptr;
2526
2527 auto *OpI = cast<CastInst>(FI.getOperand(0));
2528 Value *X = OpI->getOperand(0);
2529 Type *XType = X->getType();
2530 Type *DestType = FI.getType();
2531 bool IsInputSigned = isa<SIToFPInst>(OpI);
2532
2533 bool IsOutputSigned;
2534 if constexpr (IsSaturating)
2535 IsOutputSigned = FI.getIntrinsicID() == Intrinsic::fptosi_sat;
2536 else
2537 IsOutputSigned = isa<FPToSIInst>(FI);
2538
2539 // Since we can assume the conversion won't overflow, our decision as to
2540 // whether the input will fit in the float should depend on the minimum
2541 // of the input range and output range.
2542
2543 // This means this is also safe for a signed input and unsigned output, since
2544 // a negative input would lead to undefined behavior.
2545 if (!isKnownExactCastIntToFP(I&: *OpI)) {
2546 if constexpr (!IsSaturating) {
2547 // The first cast may not round exactly based on the source integer width
2548 // and FP width, but the overflow UB rules can still allow this to fold.
2549 // If the destination type is narrow, that means the intermediate FP value
2550 // must be large enough to hold the source value exactly.
2551 //
2552 // For example, (uint8_t)((float)(uint32_t 16777217) is UB.
2553 int OutputSize = (int)DestType->getScalarSizeInBits();
2554 if (OutputSize > OpI->getType()->getFPMantissaWidth())
2555 return nullptr;
2556 } else {
2557 // Sat intrinsics produce a defined saturated value on overflow, so
2558 // the UB-based shortcut is invalid. Require exactness.
2559 return nullptr;
2560 }
2561 }
2562
2563 unsigned SrcWidth = XType->getScalarSizeInBits();
2564 unsigned DestWidth = DestType->getScalarSizeInBits();
2565
2566 if constexpr (IsSaturating) {
2567 // TODO: cross-sign and narrowing cases could be handled with range
2568 // analysis to prove the source fits in the destination.
2569 if (IsInputSigned != IsOutputSigned || DestWidth < SrcWidth)
2570 return nullptr;
2571 }
2572
2573 if (DestWidth > SrcWidth) {
2574 if (IsInputSigned && IsOutputSigned)
2575 return new SExtInst(X, DestType);
2576 return new ZExtInst(X, DestType);
2577 }
2578 if (DestWidth < SrcWidth)
2579 return new TruncInst(X, DestType);
2580
2581 assert(XType == DestType && "Unexpected types for int to FP to int casts");
2582 return replaceInstUsesWith(I&: FI, V: X);
2583}
2584
2585template Instruction *InstCombinerImpl::foldItoFPtoI<CastInst>(CastInst &);
2586template Instruction *
2587InstCombinerImpl::foldItoFPtoI<IntrinsicInst>(IntrinsicInst &);
2588
2589static Instruction *foldFPtoI(Instruction &FI, InstCombiner &IC) {
2590 // fpto{u/s}i non-norm --> 0
2591 FPClassTest Mask =
2592 FI.getOpcode() == Instruction::FPToUI ? fcPosNormal : fcNormal;
2593 KnownFPClass FPClass = computeKnownFPClass(
2594 V: FI.getOperand(i: 0), InterestedClasses: Mask, SQ: IC.getSimplifyQuery().getWithInstruction(I: &FI));
2595 if (FPClass.isKnownNever(Mask))
2596 return IC.replaceInstUsesWith(I&: FI, V: ConstantInt::getNullValue(Ty: FI.getType()));
2597
2598 // fpto{u/s}i (trunc X) --> fpto{u/s}i X
2599 Value *Src;
2600 if (match(V: FI.getOperand(i: 0), P: m_Intrinsic<Intrinsic::trunc>(Ops: m_Value(V&: Src))))
2601 return IC.replaceOperand(I&: FI, OpNum: 0, V: Src);
2602
2603 // fpto{u/s}i (fdiv ({u/s}itofp X to F), C_fp) --> {u/s}div X, C
2604 //
2605 // F has precision p (significand bits incl. hidden bit); C_fp is the exact FP
2606 // value of the integer constant C. Given N = integer width, this is safe if:
2607 // Unsigned: C > 0 and N <= p.
2608 // Signed: C != 0 and N - 1 <= p, excluding (X == INT_MIN, C == -1) since
2609 // sdiv INT_MIN, -1 is UB while the FP path only yields poison.
2610 // fdiv X, -1 gets transformed to fneg in InstCombine regardless.
2611 //
2612 // The bounds make {u/s}itofp and C_fp exact (every |int| <= 2^p is exact),
2613 // and ensure the rounded quotient never crosses an integer boundary:
2614 // Rounding lemma: for 0 <= A <= 2^p, 1 <= B <= 2^p, q = floor(A/B),
2615 // trunc(R_p(A/B)) = q.
2616 // For r = A - qB > 0, m = q+1, half-gap H(m) <= q/2^p and
2617 // m - A/B = (B-r)/B >= 1/B > q/2^p >= H(m), so R_p(A/B) < m; q = 0 is
2618 // similar (H(1) = 2^(-p-1) < 2^-p <= 1/B).
2619 // Signed case: by symmetry R_p(-z) = -R_p(z), so fptosi yields s*q = sdiv.
2620 bool IsSigned = FI.getOpcode() == Instruction::FPToSI;
2621 Value *X;
2622 const APFloat *APF;
2623 if (IsSigned) {
2624 if (!match(V: FI.getOperand(i: 0),
2625 P: m_OneUse(SubPattern: m_FDiv(L: m_SIToFP(Op: m_Value(V&: X)), R: m_APFloat(Res&: APF)))))
2626 return nullptr;
2627 } else {
2628 if (!match(V: FI.getOperand(i: 0),
2629 P: m_OneUse(SubPattern: m_FDiv(L: m_UIToFP(Op: m_Value(V&: X)), R: m_APFloat(Res&: APF)))))
2630 return nullptr;
2631 }
2632 Type *IntTy = X->getType();
2633 if (FI.getType() != IntTy)
2634 return nullptr;
2635
2636 unsigned IntWidth = IntTy->getScalarSizeInBits();
2637 unsigned Precision = APFloat::semanticsPrecision(APF->getSemantics());
2638 if (Precision + IsSigned < IntWidth)
2639 return nullptr;
2640
2641 if (!APF->isInteger())
2642 return nullptr;
2643
2644 APSInt Divisor(IntWidth, !IsSigned);
2645 bool IsExact = false;
2646 APF->convertToInteger(Result&: Divisor, RM: APFloat::rmTowardZero, IsExact: &IsExact);
2647 if (!IsExact)
2648 return nullptr;
2649
2650 if (Divisor.isZero())
2651 return nullptr;
2652
2653 // sdiv INT_MIN, -1 is UB, not poison, so this isn't valid if X == INT_MIN.
2654 // fdiv X, -1 gets transformed to fneg anyways, so we do not handle C == -1.
2655 if (IsSigned && Divisor.isAllOnes())
2656 return nullptr;
2657
2658 Constant *C = ConstantInt::get(Ty: IntTy, V: Divisor);
2659 return IsSigned ? BinaryOperator::CreateSDiv(V1: X, V2: C)
2660 : BinaryOperator::CreateUDiv(V1: X, V2: C);
2661}
2662
2663Instruction *InstCombinerImpl::visitFPToUI(FPToUIInst &FI) {
2664 if (Instruction *I = foldItoFPtoI(FI))
2665 return I;
2666
2667 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2668 return I;
2669
2670 return commonCastTransforms(CI&: FI);
2671}
2672
2673Instruction *InstCombinerImpl::visitFPToSI(FPToSIInst &FI) {
2674 if (Instruction *I = foldItoFPtoI(FI))
2675 return I;
2676
2677 if (Instruction *I = foldFPtoI(FI, IC&: *this))
2678 return I;
2679
2680 return commonCastTransforms(CI&: FI);
2681}
2682
2683Instruction *InstCombinerImpl::visitUIToFP(CastInst &CI) {
2684 if (Instruction *R = commonCastTransforms(CI))
2685 return R;
2686 if (!CI.hasNonNeg() && isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2687 CI.setNonNeg();
2688 return &CI;
2689 }
2690
2691 // uitofp (and (trunc X), Mask) --> uitofp (and X, zext(Mask))
2692 Value *Src = CI.getOperand(i_nocapture: 0);
2693 Value *X;
2694 Constant *Mask;
2695 if (match(V: Src, P: m_OneUse(SubPattern: m_And(L: m_OneUse(SubPattern: m_Trunc(Op: m_Value(V&: X))),
2696 R: m_ImmConstant(C&: Mask))))) {
2697 unsigned SourceWidth = Src->getType()->getScalarSizeInBits();
2698 unsigned InputWidth = X->getType()->getScalarSizeInBits();
2699 if (!DL.isLegalInteger(Width: SourceWidth) &&
2700 shouldChangeType(FromBitWidth: SourceWidth, ToBitWidth: InputWidth)) {
2701 Value *MaskedX =
2702 Builder.CreateAnd(LHS: X, RHS: Builder.CreateZExt(V: Mask, DestTy: X->getType()));
2703 auto *NewUIToFP =
2704 CastInst::Create(Instruction::UIToFP, S: MaskedX, Ty: CI.getType());
2705 NewUIToFP->setNonNeg(CI.hasNonNeg());
2706 return NewUIToFP;
2707 }
2708 }
2709
2710 return nullptr;
2711}
2712
2713Instruction *InstCombinerImpl::visitSIToFP(CastInst &CI) {
2714 if (Instruction *R = commonCastTransforms(CI))
2715 return R;
2716 if (isKnownNonNegative(V: CI.getOperand(i_nocapture: 0), SQ)) {
2717 auto *UI =
2718 CastInst::Create(Instruction::UIToFP, S: CI.getOperand(i_nocapture: 0), Ty: CI.getType());
2719 UI->setNonNeg(true);
2720 // nnan/afn/reassoc/contract/arcp carry no meaning for a value-preserving
2721 // cast, but ninf/nsz are semantically meaningful for {u,s}itofp and
2722 // remain valid after reinterpreting the operand as unsigned.
2723 UI->setHasNoInfs(CI.hasNoInfs());
2724 UI->setHasNoSignedZeros(CI.hasNoSignedZeros());
2725 return UI;
2726 }
2727 return nullptr;
2728}
2729
2730Instruction *InstCombinerImpl::visitIntToPtr(IntToPtrInst &CI) {
2731 // If the source integer type is not the intptr_t type for this target, do a
2732 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
2733 // cast to be exposed to other transforms.
2734 unsigned AS = CI.getAddressSpace();
2735 if (CI.getOperand(i_nocapture: 0)->getType()->getScalarSizeInBits() !=
2736 DL.getPointerSizeInBits(AS)) {
2737 Type *Ty = CI.getOperand(i_nocapture: 0)->getType()->getWithNewType(
2738 EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2739 Value *P = Builder.CreateZExtOrTrunc(V: CI.getOperand(i_nocapture: 0), DestTy: Ty);
2740 return new IntToPtrInst(P, CI.getType());
2741 }
2742
2743 // Replace (inttoptr (add (ptrtoint %Base), %Offset)) with
2744 // (getelementptr i8, %Base, %Offset) if the pointer is only used as integer
2745 // value.
2746 Value *Base;
2747 Value *Offset;
2748 auto UsesPointerAsInt = [](User *U) {
2749 if (isa<ICmpInst, PtrToIntInst>(Val: U))
2750 return true;
2751 if (auto *P = dyn_cast<PHINode>(Val: U))
2752 return P->hasOneUse() && isa<ICmpInst, PtrToIntInst>(Val: *P->user_begin());
2753 return false;
2754 };
2755 if (match(V: CI.getOperand(i_nocapture: 0),
2756 P: m_OneUse(SubPattern: m_c_Add(L: m_PtrToIntSameSize(DL, Op: m_Value(V&: Base)),
2757 R: m_Value(V&: Offset)))) &&
2758 CI.getType()->getPointerAddressSpace() ==
2759 Base->getType()->getPointerAddressSpace() &&
2760 all_of(Range: CI.users(), P: UsesPointerAsInt)) {
2761 return GetElementPtrInst::Create(PointeeType: Builder.getInt8Ty(), Ptr: Base, IdxList: Offset);
2762 }
2763
2764 if (Instruction *I = commonCastTransforms(CI))
2765 return I;
2766
2767 return nullptr;
2768}
2769
2770Value *InstCombinerImpl::foldPtrToIntOrAddrOfGEP(Type *IntTy, Value *Ptr) {
2771 // Look through chain of one-use GEPs.
2772 Type *PtrTy = Ptr->getType();
2773 SmallVector<GEPOperator *> GEPs;
2774 while (true) {
2775 auto *GEP = dyn_cast<GEPOperator>(Val: Ptr);
2776 if (!GEP || !GEP->hasOneUse())
2777 break;
2778 GEPs.push_back(Elt: GEP);
2779 Ptr = GEP->getPointerOperand();
2780 }
2781
2782 // Don't handle case where GEP converts from pointer to vector.
2783 if (GEPs.empty() || PtrTy != Ptr->getType())
2784 return nullptr;
2785
2786 // Check whether we know the integer value of the base pointer.
2787 Value *Res;
2788 Type *IdxTy = DL.getIndexType(PtrTy);
2789 if (match(V: Ptr, P: m_OneUse(SubPattern: m_IntToPtr(Op: m_Value(V&: Res)))) &&
2790 Res->getType() == IntTy && IntTy == IdxTy) {
2791 // pass
2792 } else if (isa<ConstantPointerNull>(Val: Ptr)) {
2793 Res = Constant::getNullValue(Ty: IdxTy);
2794 } else {
2795 return nullptr;
2796 }
2797
2798 // Perform the entire operation on integers instead.
2799 for (GEPOperator *GEP : reverse(C&: GEPs)) {
2800 Value *Offset = EmitGEPOffset(GEP);
2801 Res = Builder.CreateAdd(LHS: Res, RHS: Offset, Name: "", HasNUW: GEP->hasNoUnsignedWrap());
2802 }
2803 return Builder.CreateZExtOrTrunc(V: Res, DestTy: IntTy);
2804}
2805
2806Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
2807 // If the destination integer type is not the intptr_t type for this target,
2808 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
2809 // to be exposed to other transforms.
2810 Value *SrcOp = CI.getPointerOperand();
2811 Type *SrcTy = SrcOp->getType();
2812 Type *Ty = CI.getType();
2813 unsigned AS = CI.getPointerAddressSpace();
2814 unsigned TySize = Ty->getScalarSizeInBits();
2815 unsigned PtrSize = DL.getPointerSizeInBits(AS);
2816 if (TySize != PtrSize) {
2817 Type *IntPtrTy =
2818 SrcTy->getWithNewType(EltTy: DL.getIntPtrType(C&: CI.getContext(), AddressSpace: AS));
2819 Value *P = Builder.CreatePtrToInt(V: SrcOp, DestTy: IntPtrTy);
2820 return CastInst::CreateIntegerCast(S: P, Ty, /*isSigned=*/false);
2821 }
2822
2823 // (ptrtoint (ptrmask P, M))
2824 // -> (and (ptrtoint P), M)
2825 // This is generally beneficial as `and` is better supported than `ptrmask`.
2826 Value *Ptr, *Mask;
2827 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(
2828 Ops: m_Value(V&: Ptr), Ops: m_SpecificType(RefTy: Ty, V&: Mask)))))
2829 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToInt(V: Ptr, DestTy: Ty), V2: Mask);
2830
2831 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2832 return replaceInstUsesWith(I&: CI, V);
2833
2834 Value *Vec, *Scalar, *Index;
2835 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_InsertElt(Val: m_IntToPtr(Op: m_SpecificType(RefTy: Ty, V&: Vec)),
2836 Elt: m_Value(V&: Scalar), Idx: m_Value(V&: Index))))) {
2837 assert(Vec->getType()->getScalarSizeInBits() == PtrSize && "Wrong type");
2838 // Convert the scalar to int followed by insert to eliminate one cast:
2839 // p2i (ins (i2p Vec), Scalar, Index --> ins Vec, (p2i Scalar), Index
2840 Value *NewCast = Builder.CreatePtrToInt(V: Scalar, DestTy: Ty->getScalarType());
2841 return InsertElementInst::Create(Vec, NewElt: NewCast, Idx: Index);
2842 }
2843
2844 return commonCastTransforms(CI);
2845}
2846
2847Instruction *InstCombinerImpl::visitPtrToAddr(PtrToAddrInst &CI) {
2848 Value *SrcOp = CI.getPointerOperand();
2849 Type *Ty = CI.getType();
2850
2851 // (ptrtoaddr (ptrmask P, M))
2852 // -> (and (ptrtoaddr P), M)
2853 // This is generally beneficial as `and` is better supported than `ptrmask`.
2854 Value *Ptr, *Mask;
2855 if (match(V: SrcOp, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ptrmask>(
2856 Ops: m_Value(V&: Ptr), Ops: m_SpecificType(RefTy: Ty, V&: Mask)))))
2857 return BinaryOperator::CreateAnd(V1: Builder.CreatePtrToAddr(V: Ptr), V2: Mask);
2858
2859 if (Value *V = foldPtrToIntOrAddrOfGEP(IntTy: Ty, Ptr: SrcOp))
2860 return replaceInstUsesWith(I&: CI, V);
2861
2862 // FIXME: Implement variants of ptrtoint folds.
2863 return commonCastTransforms(CI);
2864}
2865
2866/// This input value (which is known to have vector type) is being zero extended
2867/// or truncated to the specified vector type. Since the zext/trunc is done
2868/// using an integer type, we have a (bitcast(cast(bitcast))) pattern,
2869/// endianness will impact which end of the vector that is extended or
2870/// truncated.
2871///
2872/// A vector is always stored with index 0 at the lowest address, which
2873/// corresponds to the most significant bits for a big endian stored integer and
2874/// the least significant bits for little endian. A trunc/zext of an integer
2875/// impacts the big end of the integer. Thus, we need to add/remove elements at
2876/// the front of the vector for big endian targets, and the back of the vector
2877/// for little endian targets.
2878///
2879/// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
2880///
2881/// The source and destination vector types may have different element types.
2882static Instruction *
2883optimizeVectorResizeWithIntegerBitCasts(Value *InVal, VectorType *DestTy,
2884 InstCombinerImpl &IC) {
2885 // We can only do this optimization if the output is a multiple of the input
2886 // element size, or the input is a multiple of the output element size.
2887 // Convert the input type to have the same element type as the output.
2888 VectorType *SrcTy = cast<VectorType>(Val: InVal->getType());
2889
2890 if (SrcTy->getElementType() != DestTy->getElementType()) {
2891 // The input types don't need to be identical, but for now they must be the
2892 // same size. There is no specific reason we couldn't handle things like
2893 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
2894 // there yet.
2895 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
2896 DestTy->getElementType()->getPrimitiveSizeInBits())
2897 return nullptr;
2898
2899 SrcTy =
2900 FixedVectorType::get(ElementType: DestTy->getElementType(),
2901 NumElts: cast<FixedVectorType>(Val: SrcTy)->getNumElements());
2902 InVal = IC.Builder.CreateBitCast(V: InVal, DestTy: SrcTy);
2903 }
2904
2905 bool IsBigEndian = IC.getDataLayout().isBigEndian();
2906 unsigned SrcElts = cast<FixedVectorType>(Val: SrcTy)->getNumElements();
2907 unsigned DestElts = cast<FixedVectorType>(Val: DestTy)->getNumElements();
2908
2909 assert(SrcElts != DestElts && "Element counts should be different.");
2910
2911 // Now that the element types match, get the shuffle mask and RHS of the
2912 // shuffle to use, which depends on whether we're increasing or decreasing the
2913 // size of the input.
2914 auto ShuffleMaskStorage = llvm::to_vector<16>(Range: llvm::seq<int>(Begin: 0, End: SrcElts));
2915 ArrayRef<int> ShuffleMask;
2916 Value *V2;
2917
2918 if (SrcElts > DestElts) {
2919 // If we're shrinking the number of elements (rewriting an integer
2920 // truncate), just shuffle in the elements corresponding to the least
2921 // significant bits from the input and use poison as the second shuffle
2922 // input.
2923 V2 = PoisonValue::get(T: SrcTy);
2924 // Make sure the shuffle mask selects the "least significant bits" by
2925 // keeping elements from back of the src vector for big endian, and from the
2926 // front for little endian.
2927 ShuffleMask = ShuffleMaskStorage;
2928 if (IsBigEndian)
2929 ShuffleMask = ShuffleMask.take_back(N: DestElts);
2930 else
2931 ShuffleMask = ShuffleMask.take_front(N: DestElts);
2932 } else {
2933 // If we're increasing the number of elements (rewriting an integer zext),
2934 // shuffle in all of the elements from InVal. Fill the rest of the result
2935 // elements with zeros from a constant zero.
2936 V2 = Constant::getNullValue(Ty: SrcTy);
2937 // Use first elt from V2 when indicating zero in the shuffle mask.
2938 uint32_t NullElt = SrcElts;
2939 // Extend with null values in the "most significant bits" by adding elements
2940 // in front of the src vector for big endian, and at the back for little
2941 // endian.
2942 unsigned DeltaElts = DestElts - SrcElts;
2943 if (IsBigEndian)
2944 ShuffleMaskStorage.insert(I: ShuffleMaskStorage.begin(), NumToInsert: DeltaElts, Elt: NullElt);
2945 else
2946 ShuffleMaskStorage.append(NumInputs: DeltaElts, Elt: NullElt);
2947 ShuffleMask = ShuffleMaskStorage;
2948 }
2949
2950 return new ShuffleVectorInst(InVal, V2, ShuffleMask);
2951}
2952
2953static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
2954 return Value % Ty->getPrimitiveSizeInBits() == 0;
2955}
2956
2957static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
2958 return Value / Ty->getPrimitiveSizeInBits();
2959}
2960
2961/// V is a value which is inserted into a vector of VecEltTy.
2962/// Look through the value to see if we can decompose it into
2963/// insertions into the vector. See the example in the comment for
2964/// OptimizeIntegerToVectorInsertions for the pattern this handles.
2965/// The type of V is always a non-zero multiple of VecEltTy's size.
2966/// Shift is the number of bits between the lsb of V and the lsb of
2967/// the vector.
2968///
2969/// This returns false if the pattern can't be matched or true if it can,
2970/// filling in Elements with the elements found here.
2971static bool collectInsertionElements(Value *V, unsigned Shift,
2972 SmallVectorImpl<Value *> &Elements,
2973 Type *VecEltTy, bool isBigEndian) {
2974 assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
2975 "Shift should be a multiple of the element type size");
2976
2977 // Poison values never contribute useful bits to the result.
2978 if (match(V, P: m_Poison()))
2979 return true;
2980
2981 // If we got down to a value of the right type, we win, try inserting into the
2982 // right element.
2983 if (V->getType() == VecEltTy) {
2984 // Inserting null doesn't actually insert any elements.
2985 if (Constant *C = dyn_cast<Constant>(Val: V))
2986 if (C->isNullValue())
2987 return true;
2988
2989 unsigned ElementIndex = getTypeSizeIndex(Value: Shift, Ty: VecEltTy);
2990 if (isBigEndian)
2991 ElementIndex = Elements.size() - ElementIndex - 1;
2992
2993 // Fail if multiple elements are inserted into this slot.
2994 if (Elements[ElementIndex])
2995 return false;
2996
2997 Elements[ElementIndex] = V;
2998 return true;
2999 }
3000
3001 if (Constant *C = dyn_cast<Constant>(Val: V)) {
3002 // Figure out the # elements this provides, and bitcast it or slice it up
3003 // as required.
3004 unsigned NumElts = getTypeSizeIndex(Value: C->getType()->getPrimitiveSizeInBits(),
3005 Ty: VecEltTy);
3006 // If the constant is the size of a vector element, we just need to bitcast
3007 // it to the right type so it gets properly inserted.
3008 if (NumElts == 1)
3009 return collectInsertionElements(V: ConstantExpr::getBitCast(C, Ty: VecEltTy),
3010 Shift, Elements, VecEltTy, isBigEndian);
3011
3012 // Okay, this is a constant that covers multiple elements. Slice it up into
3013 // pieces and insert each element-sized piece into the vector.
3014 if (!isa<IntegerType>(Val: C->getType()))
3015 C = ConstantExpr::getBitCast(C, Ty: IntegerType::get(C&: V->getContext(),
3016 NumBits: C->getType()->getPrimitiveSizeInBits()));
3017 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
3018 Type *ElementIntTy = IntegerType::get(C&: C->getContext(), NumBits: ElementSize);
3019
3020 for (unsigned i = 0; i != NumElts; ++i) {
3021 unsigned ShiftI = i * ElementSize;
3022 Constant *Piece = ConstantFoldBinaryInstruction(
3023 Opcode: Instruction::LShr, V1: C, V2: ConstantInt::get(Ty: C->getType(), V: ShiftI));
3024 if (!Piece)
3025 return false;
3026
3027 Piece = ConstantExpr::getTrunc(C: Piece, Ty: ElementIntTy);
3028 if (!collectInsertionElements(V: Piece, Shift: ShiftI + Shift, Elements, VecEltTy,
3029 isBigEndian))
3030 return false;
3031 }
3032 return true;
3033 }
3034
3035 if (!V->hasOneUse()) return false;
3036
3037 Instruction *I = dyn_cast<Instruction>(Val: V);
3038 if (!I) return false;
3039 switch (I->getOpcode()) {
3040 default: return false; // Unhandled case.
3041 case Instruction::BitCast:
3042 if (I->getOperand(i: 0)->getType()->isVectorTy())
3043 return false;
3044 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
3045 isBigEndian);
3046 case Instruction::ZExt:
3047 if (!isMultipleOfTypeSize(
3048 Value: I->getOperand(i: 0)->getType()->getPrimitiveSizeInBits(),
3049 Ty: VecEltTy))
3050 return false;
3051 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
3052 isBigEndian);
3053 case Instruction::Or:
3054 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
3055 isBigEndian) &&
3056 collectInsertionElements(V: I->getOperand(i: 1), Shift, Elements, VecEltTy,
3057 isBigEndian);
3058 case Instruction::Shl: {
3059 // Must be shifting by a constant that is a multiple of the element size.
3060 ConstantInt *CI = dyn_cast<ConstantInt>(Val: I->getOperand(i: 1));
3061 if (!CI) return false;
3062 Shift += CI->getZExtValue();
3063 if (!isMultipleOfTypeSize(Value: Shift, Ty: VecEltTy)) return false;
3064 return collectInsertionElements(V: I->getOperand(i: 0), Shift, Elements, VecEltTy,
3065 isBigEndian);
3066 }
3067
3068 }
3069}
3070
3071
3072/// If the input is an 'or' instruction, we may be doing shifts and ors to
3073/// assemble the elements of the vector manually.
3074/// Try to rip the code out and replace it with insertelements. This is to
3075/// optimize code like this:
3076///
3077/// %tmp37 = bitcast float %inc to i32
3078/// %tmp38 = zext i32 %tmp37 to i64
3079/// %tmp31 = bitcast float %inc5 to i32
3080/// %tmp32 = zext i32 %tmp31 to i64
3081/// %tmp33 = shl i64 %tmp32, 32
3082/// %ins35 = or i64 %tmp33, %tmp38
3083/// %tmp43 = bitcast i64 %ins35 to <2 x float>
3084///
3085/// Into two insertelements that do "buildvector{%inc, %inc5}".
3086static Value *optimizeIntegerToVectorInsertions(BitCastInst &CI,
3087 InstCombinerImpl &IC) {
3088 auto *DestVecTy = cast<FixedVectorType>(Val: CI.getType());
3089 Value *IntInput = CI.getOperand(i_nocapture: 0);
3090
3091 // if the int input is just an undef value do not try to optimize to vector
3092 // insertions as it will prevent undef propagation
3093 if (isa<UndefValue>(Val: IntInput))
3094 return nullptr;
3095
3096 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
3097 if (!collectInsertionElements(V: IntInput, Shift: 0, Elements,
3098 VecEltTy: DestVecTy->getElementType(),
3099 isBigEndian: IC.getDataLayout().isBigEndian()))
3100 return nullptr;
3101
3102 // If we succeeded, we know that all of the element are specified by Elements
3103 // or are zero if Elements has a null entry. Recast this as a set of
3104 // insertions.
3105 Value *Result = Constant::getNullValue(Ty: CI.getType());
3106 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
3107 if (!Elements[i]) continue; // Unset element.
3108
3109 Result = IC.Builder.CreateInsertElement(Vec: Result, NewElt: Elements[i], Idx: i);
3110 }
3111
3112 return Result;
3113}
3114
3115/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
3116/// vector followed by extract element. The backend tends to handle bitcasts of
3117/// vectors better than bitcasts of scalars because vector registers are
3118/// usually not type-specific like scalar integer or scalar floating-point.
3119static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast,
3120 InstCombinerImpl &IC) {
3121 Value *VecOp, *Index;
3122 if (!match(V: BitCast.getOperand(i_nocapture: 0),
3123 P: m_OneUse(SubPattern: m_ExtractElt(Val: m_Value(V&: VecOp), Idx: m_Value(V&: Index)))))
3124 return nullptr;
3125
3126 // The bitcast must be to a vectorizable type, otherwise we can't make a new
3127 // type to extract from.
3128 Type *DestType = BitCast.getType();
3129 VectorType *VecType = cast<VectorType>(Val: VecOp->getType());
3130 if (VectorType::isValidElementType(ElemTy: DestType)) {
3131 auto *NewVecType = VectorType::get(ElementType: DestType, Other: VecType);
3132 auto *NewBC = IC.Builder.CreateBitCast(V: VecOp, DestTy: NewVecType, Name: "bc");
3133 return ExtractElementInst::Create(Vec: NewBC, Idx: Index);
3134 }
3135
3136 // Only solve DestType is vector to avoid inverse transform in visitBitCast.
3137 // bitcast (extractelement <1 x elt>, dest) -> bitcast(<1 x elt>, dest)
3138 auto *FixedVType = dyn_cast<FixedVectorType>(Val: VecType);
3139 if (DestType->isVectorTy() && FixedVType && FixedVType->getNumElements() == 1)
3140 return CastInst::Create(Instruction::BitCast, S: VecOp, Ty: DestType);
3141
3142 return nullptr;
3143}
3144
3145/// Change the type of a bitwise logic operation if we can eliminate a bitcast.
3146static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast,
3147 InstCombiner::BuilderTy &Builder) {
3148 Type *DestTy = BitCast.getType();
3149 BinaryOperator *BO;
3150
3151 if (!match(V: BitCast.getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BinOp(I&: BO))) ||
3152 !BO->isBitwiseLogicOp())
3153 return nullptr;
3154
3155 // FIXME: This transform is restricted to vector types to avoid backend
3156 // problems caused by creating potentially illegal operations. If a fix-up is
3157 // added to handle that situation, we can remove this check.
3158 if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
3159 return nullptr;
3160
3161 if (DestTy->isFPOrFPVectorTy()) {
3162 Value *X, *Y;
3163 // bitcast(logic(bitcast(X), bitcast(Y))) -> bitcast'(logic(bitcast'(X), Y))
3164 if (match(V: BO->getOperand(i_nocapture: 0), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: X)))) &&
3165 match(V: BO->getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_BitCast(Op: m_Value(V&: Y))))) {
3166 if (X->getType()->isFPOrFPVectorTy() &&
3167 Y->getType()->isIntOrIntVectorTy()) {
3168 Value *CastedOp =
3169 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy: Y->getType());
3170 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: Y);
3171 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
3172 }
3173 if (X->getType()->isIntOrIntVectorTy() &&
3174 Y->getType()->isFPOrFPVectorTy()) {
3175 Value *CastedOp =
3176 Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy: X->getType());
3177 Value *NewBO = Builder.CreateBinOp(Opc: BO->getOpcode(), LHS: CastedOp, RHS: X);
3178 return CastInst::CreateBitOrPointerCast(S: NewBO, Ty: DestTy);
3179 }
3180 }
3181 return nullptr;
3182 }
3183
3184 if (!DestTy->isIntOrIntVectorTy())
3185 return nullptr;
3186
3187 Value *X;
3188 if (match(V: BO->getOperand(i_nocapture: 0),
3189 P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3190 !isa<Constant>(Val: X)) {
3191 // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
3192 Value *CastedOp1 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 1), DestTy);
3193 return BinaryOperator::Create(Op: BO->getOpcode(), S1: X, S2: CastedOp1);
3194 }
3195
3196 if (match(V: BO->getOperand(i_nocapture: 1),
3197 P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3198 !isa<Constant>(Val: X)) {
3199 // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
3200 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
3201 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: X);
3202 }
3203
3204 // Canonicalize vector bitcasts to come before vector bitwise logic with a
3205 // constant. This eases recognition of special constants for later ops.
3206 // Example:
3207 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
3208 Constant *C;
3209 if (match(V: BO->getOperand(i_nocapture: 1), P: m_Constant(C))) {
3210 // bitcast (logic X, C) --> logic (bitcast X, C')
3211 Value *CastedOp0 = Builder.CreateBitCast(V: BO->getOperand(i_nocapture: 0), DestTy);
3212 Value *CastedC = Builder.CreateBitCast(V: C, DestTy);
3213 return BinaryOperator::Create(Op: BO->getOpcode(), S1: CastedOp0, S2: CastedC);
3214 }
3215
3216 return nullptr;
3217}
3218
3219/// Change the type of a select if we can eliminate a bitcast.
3220static Instruction *foldBitCastSelect(BitCastInst &BitCast,
3221 InstCombiner::BuilderTy &Builder) {
3222 Value *Cond, *TVal, *FVal;
3223 if (!match(V: BitCast.getOperand(i_nocapture: 0),
3224 P: m_OneUse(SubPattern: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: TVal), R: m_Value(V&: FVal)))))
3225 return nullptr;
3226
3227 // A vector select must maintain the same number of elements in its operands.
3228 Type *CondTy = Cond->getType();
3229 Type *DestTy = BitCast.getType();
3230
3231 auto *DestVecTy = dyn_cast<VectorType>(Val: DestTy);
3232
3233 if (auto *CondVTy = dyn_cast<VectorType>(Val: CondTy))
3234 if (!DestVecTy ||
3235 CondVTy->getElementCount() != DestVecTy->getElementCount())
3236 return nullptr;
3237
3238 auto *Sel = cast<Instruction>(Val: BitCast.getOperand(i_nocapture: 0));
3239 auto *SrcVecTy = dyn_cast<VectorType>(Val: TVal->getType());
3240
3241 if ((isa<Constant>(Val: TVal) || isa<Constant>(Val: FVal)) &&
3242 (!DestVecTy ||
3243 (SrcVecTy && ElementCount::isKnownLE(LHS: DestVecTy->getElementCount(),
3244 RHS: SrcVecTy->getElementCount())))) {
3245 // Avoid introducing select of vector (or select of vector with more
3246 // elements) until the backend can undo this transformation.
3247 Value *CastedTVal = Builder.CreateBitCast(V: TVal, DestTy);
3248 Value *CastedFVal = Builder.CreateBitCast(V: FVal, DestTy);
3249 return SelectInst::Create(C: Cond, S1: CastedTVal, S2: CastedFVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3250 }
3251
3252 // FIXME: This transform is restricted from changing the select between
3253 // scalars and vectors to avoid backend problems caused by creating
3254 // potentially illegal operations. If a fix-up is added to handle that
3255 // situation, we can remove this check.
3256 if ((DestVecTy != nullptr) != (SrcVecTy != nullptr))
3257 return nullptr;
3258
3259 Value *X;
3260 if (match(V: TVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3261 !isa<Constant>(Val: X)) {
3262 // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
3263 Value *CastedVal = Builder.CreateBitCast(V: FVal, DestTy);
3264 return SelectInst::Create(C: Cond, S1: X, S2: CastedVal, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3265 }
3266
3267 if (match(V: FVal, P: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X)))) &&
3268 !isa<Constant>(Val: X)) {
3269 // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
3270 Value *CastedVal = Builder.CreateBitCast(V: TVal, DestTy);
3271 return SelectInst::Create(C: Cond, S1: CastedVal, S2: X, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
3272 }
3273
3274 return nullptr;
3275}
3276
3277/// Check if all users of CI are StoreInsts.
3278static bool hasStoreUsersOnly(CastInst &CI) {
3279 for (User *U : CI.users()) {
3280 if (!isa<StoreInst>(Val: U))
3281 return false;
3282 }
3283 return true;
3284}
3285
3286/// This function handles following case
3287///
3288/// A -> B cast
3289/// PHI
3290/// B -> A cast
3291///
3292/// All the related PHI nodes can be replaced by new PHI nodes with type A.
3293/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
3294Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
3295 PHINode *PN) {
3296 // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
3297 if (hasStoreUsersOnly(CI))
3298 return nullptr;
3299
3300 Value *Src = CI.getOperand(i_nocapture: 0);
3301 Type *SrcTy = Src->getType(); // Type B
3302 Type *DestTy = CI.getType(); // Type A
3303
3304 SmallVector<PHINode *, 4> PhiWorklist;
3305 SmallSetVector<PHINode *, 4> OldPhiNodes;
3306
3307 // Find all of the A->B casts and PHI nodes.
3308 // We need to inspect all related PHI nodes, but PHIs can be cyclic, so
3309 // OldPhiNodes is used to track all known PHI nodes, before adding a new
3310 // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
3311 PhiWorklist.push_back(Elt: PN);
3312 OldPhiNodes.insert(X: PN);
3313 while (!PhiWorklist.empty()) {
3314 auto *OldPN = PhiWorklist.pop_back_val();
3315 for (Value *IncValue : OldPN->incoming_values()) {
3316 if (isa<Constant>(Val: IncValue))
3317 continue;
3318
3319 if (auto *LI = dyn_cast<LoadInst>(Val: IncValue)) {
3320 // If there is a sequence of one or more load instructions, each loaded
3321 // value is used as address of later load instruction, bitcast is
3322 // necessary to change the value type, don't optimize it. For
3323 // simplicity we give up if the load address comes from another load.
3324 Value *Addr = LI->getOperand(i_nocapture: 0);
3325 if (Addr == &CI || isa<LoadInst>(Val: Addr))
3326 return nullptr;
3327 // Don't tranform "load <256 x i32>, <256 x i32>*" to
3328 // "load x86_amx, x86_amx*", because x86_amx* is invalid.
3329 // TODO: Remove this check when bitcast between vector and x86_amx
3330 // is replaced with a specific intrinsic.
3331 if (DestTy->isX86_AMXTy())
3332 return nullptr;
3333 if (LI->hasOneUse() && LI->isSimple())
3334 continue;
3335 // If a LoadInst has more than one use, changing the type of loaded
3336 // value may create another bitcast.
3337 return nullptr;
3338 }
3339
3340 if (auto *PNode = dyn_cast<PHINode>(Val: IncValue)) {
3341 if (OldPhiNodes.insert(X: PNode))
3342 PhiWorklist.push_back(Elt: PNode);
3343 continue;
3344 }
3345
3346 auto *BCI = dyn_cast<BitCastInst>(Val: IncValue);
3347 // We can't handle other instructions.
3348 if (!BCI)
3349 return nullptr;
3350
3351 // Verify it's a A->B cast.
3352 Type *TyA = BCI->getOperand(i_nocapture: 0)->getType();
3353 Type *TyB = BCI->getType();
3354 if (TyA != DestTy || TyB != SrcTy)
3355 return nullptr;
3356 }
3357 }
3358
3359 // Check that each user of each old PHI node is something that we can
3360 // rewrite, so that all of the old PHI nodes can be cleaned up afterwards.
3361 for (auto *OldPN : OldPhiNodes) {
3362 for (User *V : OldPN->users()) {
3363 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3364 if (!SI->isSimple() || SI->getOperand(i_nocapture: 0) != OldPN)
3365 return nullptr;
3366 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3367 // Verify it's a B->A cast.
3368 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3369 Type *TyA = BCI->getType();
3370 if (TyA != DestTy || TyB != SrcTy)
3371 return nullptr;
3372 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3373 // As long as the user is another old PHI node, then even if we don't
3374 // rewrite it, the PHI web we're considering won't have any users
3375 // outside itself, so it'll be dead.
3376 if (!OldPhiNodes.contains(key: PHI))
3377 return nullptr;
3378 } else {
3379 return nullptr;
3380 }
3381 }
3382 }
3383
3384 // For each old PHI node, create a corresponding new PHI node with a type A.
3385 SmallDenseMap<PHINode *, PHINode *> NewPNodes;
3386 for (auto *OldPN : OldPhiNodes) {
3387 Builder.SetInsertPoint(OldPN);
3388 PHINode *NewPN = Builder.CreatePHI(Ty: DestTy, NumReservedValues: OldPN->getNumOperands());
3389 NewPNodes[OldPN] = NewPN;
3390 }
3391
3392 // Fill in the operands of new PHI nodes.
3393 for (auto *OldPN : OldPhiNodes) {
3394 PHINode *NewPN = NewPNodes[OldPN];
3395 for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
3396 Value *V = OldPN->getOperand(i_nocapture: j);
3397 Value *NewV = nullptr;
3398 if (auto *C = dyn_cast<Constant>(Val: V)) {
3399 NewV = ConstantExpr::getBitCast(C, Ty: DestTy);
3400 } else if (auto *LI = dyn_cast<LoadInst>(Val: V)) {
3401 // Explicitly perform load combine to make sure no opposing transform
3402 // can remove the bitcast in the meantime and trigger an infinite loop.
3403 Builder.SetInsertPoint(LI);
3404 NewV = combineLoadToNewType(LI&: *LI, NewTy: DestTy);
3405 // Remove the old load and its use in the old phi, which itself becomes
3406 // dead once the whole transform finishes.
3407 replaceInstUsesWith(I&: *LI, V: PoisonValue::get(T: LI->getType()));
3408 eraseInstFromFunction(I&: *LI);
3409 } else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3410 NewV = BCI->getOperand(i_nocapture: 0);
3411 } else if (auto *PrevPN = dyn_cast<PHINode>(Val: V)) {
3412 NewV = NewPNodes[PrevPN];
3413 }
3414 assert(NewV);
3415 NewPN->addIncoming(V: NewV, BB: OldPN->getIncomingBlock(i: j));
3416 }
3417 }
3418
3419 // Traverse all accumulated PHI nodes and process its users,
3420 // which are Stores and BitcCasts. Without this processing
3421 // NewPHI nodes could be replicated and could lead to extra
3422 // moves generated after DeSSA.
3423 // If there is a store with type B, change it to type A.
3424
3425
3426 // Replace users of BitCast B->A with NewPHI. These will help
3427 // later to get rid off a closure formed by OldPHI nodes.
3428 Instruction *RetVal = nullptr;
3429 for (auto *OldPN : OldPhiNodes) {
3430 PHINode *NewPN = NewPNodes[OldPN];
3431 for (User *V : make_early_inc_range(Range: OldPN->users())) {
3432 if (auto *SI = dyn_cast<StoreInst>(Val: V)) {
3433 assert(SI->isSimple() && SI->getOperand(0) == OldPN);
3434 Builder.SetInsertPoint(SI);
3435 auto *NewBC =
3436 cast<BitCastInst>(Val: Builder.CreateBitCast(V: NewPN, DestTy: SrcTy));
3437 SI->setOperand(i_nocapture: 0, Val_nocapture: NewBC);
3438 Worklist.push(I: SI);
3439 assert(hasStoreUsersOnly(*NewBC));
3440 }
3441 else if (auto *BCI = dyn_cast<BitCastInst>(Val: V)) {
3442 Type *TyB = BCI->getOperand(i_nocapture: 0)->getType();
3443 Type *TyA = BCI->getType();
3444 assert(TyA == DestTy && TyB == SrcTy);
3445 (void) TyA;
3446 (void) TyB;
3447 Instruction *I = replaceInstUsesWith(I&: *BCI, V: NewPN);
3448 if (BCI == &CI)
3449 RetVal = I;
3450 } else if (auto *PHI = dyn_cast<PHINode>(Val: V)) {
3451 assert(OldPhiNodes.contains(PHI));
3452 (void) PHI;
3453 } else {
3454 llvm_unreachable("all uses should be handled");
3455 }
3456 }
3457 }
3458
3459 return RetVal;
3460}
3461
3462/// Fold (bitcast (or (and (bitcast X to int), signmask), nneg Y) to fp) to
3463/// copysign((bitcast Y to fp), X)
3464static Value *foldCopySignIdioms(BitCastInst &CI,
3465 InstCombiner::BuilderTy &Builder,
3466 const SimplifyQuery &SQ) {
3467 Value *X, *Y;
3468 Type *FTy = CI.getType();
3469 if (!FTy->isFPOrFPVectorTy())
3470 return nullptr;
3471 if (!match(V: &CI, P: m_ElementWiseBitCast(Op: m_c_Or(
3472 L: m_And(L: m_ElementWiseBitCast(Op: m_Value(V&: X)), R: m_SignMask()),
3473 R: m_Value(V&: Y)))))
3474 return nullptr;
3475 if (X->getType() != FTy)
3476 return nullptr;
3477 if (!isKnownNonNegative(V: Y, SQ))
3478 return nullptr;
3479
3480 return Builder.CreateCopySign(LHS: Builder.CreateBitCast(V: Y, DestTy: FTy), RHS: X);
3481}
3482
3483Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
3484 // If the operands are integer typed then apply the integer transforms,
3485 // otherwise just apply the common ones.
3486 Value *Src = CI.getOperand(i_nocapture: 0);
3487 Type *SrcTy = Src->getType();
3488 Type *DestTy = CI.getType();
3489
3490 // Get rid of casts from one type to the same type. These are useless and can
3491 // be replaced by the operand.
3492 if (DestTy == Src->getType())
3493 return replaceInstUsesWith(I&: CI, V: Src);
3494
3495 if (isa<FixedVectorType>(Val: DestTy)) {
3496 if (isa<IntegerType>(Val: SrcTy)) {
3497 // If this is a cast from an integer to vector, check to see if the input
3498 // is a trunc or zext of a bitcast from vector. If so, we can replace all
3499 // the casts with a shuffle and (potentially) a bitcast.
3500 if (isa<TruncInst>(Val: Src) || isa<ZExtInst>(Val: Src)) {
3501 CastInst *SrcCast = cast<CastInst>(Val: Src);
3502 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(Val: SrcCast->getOperand(i_nocapture: 0)))
3503 if (isa<VectorType>(Val: BCIn->getOperand(i_nocapture: 0)->getType()))
3504 if (Instruction *I = optimizeVectorResizeWithIntegerBitCasts(
3505 InVal: BCIn->getOperand(i_nocapture: 0), DestTy: cast<VectorType>(Val: DestTy), IC&: *this))
3506 return I;
3507 }
3508
3509 // If the input is an 'or' instruction, we may be doing shifts and ors to
3510 // assemble the elements of the vector manually. Try to rip the code out
3511 // and replace it with insertelements.
3512 if (Value *V = optimizeIntegerToVectorInsertions(CI, IC&: *this))
3513 return replaceInstUsesWith(I&: CI, V);
3514 }
3515 }
3516
3517 if (FixedVectorType *SrcVTy = dyn_cast<FixedVectorType>(Val: SrcTy)) {
3518 if (SrcVTy->getNumElements() == 1) {
3519 // If our destination is not a vector, then make this a straight
3520 // scalar-scalar cast.
3521 if (!DestTy->isVectorTy()) {
3522 Value *Elem = Builder.CreateExtractElement(Vec: Src, Idx: uint64_t{0});
3523 return CastInst::Create(Instruction::BitCast, S: Elem, Ty: DestTy);
3524 }
3525
3526 // Otherwise, see if our source is an insert. If so, then use the scalar
3527 // component directly:
3528 // bitcast (inselt <1 x elt> V, X, 0) to <n x m> --> bitcast X to <n x m>
3529 if (auto *InsElt = dyn_cast<InsertElementInst>(Val: Src))
3530 return new BitCastInst(InsElt->getOperand(i_nocapture: 1), DestTy);
3531 }
3532
3533 // Convert an artificial vector insert into more analyzable bitwise logic.
3534 unsigned BitWidth = DestTy->getScalarSizeInBits();
3535 Value *X, *Y;
3536 uint64_t IndexC;
3537 if (match(V: Src, P: m_OneUse(SubPattern: m_InsertElt(
3538 Val: m_OneUse(SubPattern: m_BitCast(Op: m_SpecificType(RefTy: DestTy, V&: X))),
3539 Elt: m_Value(V&: Y), Idx: m_ConstantInt(V&: IndexC)))) &&
3540 DestTy->isIntegerTy() && Y->getType()->isIntegerTy() &&
3541 isDesirableIntType(BitWidth)) {
3542 // Adjust for big endian - the LSBs are at the high index.
3543 if (DL.isBigEndian())
3544 IndexC = SrcVTy->getNumElements() - 1 - IndexC;
3545
3546 // We only handle (endian-normalized) insert to index 0. Any other insert
3547 // would require a left-shift, so that is an extra instruction.
3548 if (IndexC == 0) {
3549 // bitcast (inselt (bitcast X), Y, 0) --> or (and X, MaskC), (zext Y)
3550 unsigned EltWidth = Y->getType()->getScalarSizeInBits();
3551 APInt MaskC = APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - EltWidth);
3552 Value *AndX = Builder.CreateAnd(LHS: X, RHS: MaskC);
3553 Value *ZextY = Builder.CreateZExt(V: Y, DestTy);
3554 return BinaryOperator::CreateOr(V1: AndX, V2: ZextY);
3555 }
3556 }
3557 }
3558
3559 if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Val: Src)) {
3560 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
3561 // a bitcast to a vector with the same # elts.
3562 Value *ShufOp0 = Shuf->getOperand(i_nocapture: 0);
3563 Value *ShufOp1 = Shuf->getOperand(i_nocapture: 1);
3564 auto ShufElts = cast<VectorType>(Val: Shuf->getType())->getElementCount();
3565 auto SrcVecElts = cast<VectorType>(Val: ShufOp0->getType())->getElementCount();
3566 if (Shuf->hasOneUse() && DestTy->isVectorTy() &&
3567 cast<VectorType>(Val: DestTy)->getElementCount() == ShufElts &&
3568 ShufElts == SrcVecElts) {
3569 BitCastInst *Tmp;
3570 // If either of the operands is a cast from CI.getType(), then
3571 // evaluating the shuffle in the casted destination's type will allow
3572 // us to eliminate at least one cast.
3573 if (((Tmp = dyn_cast<BitCastInst>(Val: ShufOp0)) &&
3574 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy) ||
3575 ((Tmp = dyn_cast<BitCastInst>(Val: ShufOp1)) &&
3576 Tmp->getOperand(i_nocapture: 0)->getType() == DestTy)) {
3577 Value *LHS = Builder.CreateBitCast(V: ShufOp0, DestTy);
3578 Value *RHS = Builder.CreateBitCast(V: ShufOp1, DestTy);
3579 // Return a new shuffle vector. Use the same element ID's, as we
3580 // know the vector types match #elts.
3581 return new ShuffleVectorInst(LHS, RHS, Shuf->getShuffleMask());
3582 }
3583 }
3584
3585 // A bitcasted-to-scalar and byte/bit reversing shuffle is better recognized
3586 // as a byte/bit swap:
3587 // bitcast <N x i8> (shuf X, undef, <N, N-1,...0>) -> bswap (bitcast X)
3588 // bitcast <N x i1> (shuf X, undef, <N, N-1,...0>) -> bitreverse (bitcast X)
3589 if (DestTy->isIntegerTy() && ShufElts.getKnownMinValue() % 2 == 0 &&
3590 Shuf->hasOneUse() && Shuf->isReverse() && match(V: ShufOp1, P: m_Poison())) {
3591 unsigned IntrinsicNum = 0;
3592 if (DL.isLegalInteger(Width: DestTy->getScalarSizeInBits()) &&
3593 SrcTy->getScalarSizeInBits() == 8) {
3594 IntrinsicNum = Intrinsic::bswap;
3595 } else if (SrcTy->getScalarSizeInBits() == 1) {
3596 IntrinsicNum = Intrinsic::bitreverse;
3597 }
3598 if (IntrinsicNum != 0) {
3599 assert(ShufOp0->getType() == SrcTy && "Unexpected shuffle mask");
3600 Function *BswapOrBitreverse = Intrinsic::getOrInsertDeclaration(
3601 M: CI.getModule(), id: IntrinsicNum, OverloadTys: DestTy);
3602 Value *ScalarX = Builder.CreateBitCast(V: ShufOp0, DestTy);
3603 return CallInst::Create(Func: BswapOrBitreverse, Args: {ScalarX});
3604 }
3605 }
3606 }
3607
3608 // Handle the A->B->A cast, and there is an intervening PHI node.
3609 if (PHINode *PN = dyn_cast<PHINode>(Val: Src))
3610 if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
3611 return I;
3612
3613 if (Instruction *I = canonicalizeBitCastExtElt(BitCast&: CI, IC&: *this))
3614 return I;
3615
3616 if (Instruction *I = foldBitCastBitwiseLogic(BitCast&: CI, Builder))
3617 return I;
3618
3619 if (Instruction *I = foldBitCastSelect(BitCast&: CI, Builder))
3620 return I;
3621
3622 if (Value *V = foldCopySignIdioms(CI, Builder, SQ: SQ.getWithInstruction(I: &CI)))
3623 return replaceInstUsesWith(I&: CI, V);
3624
3625 return commonCastTransforms(CI);
3626}
3627
3628Instruction *InstCombinerImpl::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
3629 return commonCastTransforms(CI);
3630}
3631