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Chris Lattner2b295a02010-01-04 07:53:58 +00001//===- InstCombineCasts.cpp -----------------------------------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the visit functions for cast operations.
11//
12//===----------------------------------------------------------------------===//
13
Chandler Carrutha9174582015-01-22 05:25:13 +000014#include "InstCombineInternal.h"
Guozhi Weiae541f62016-10-25 20:43:42 +000015#include "llvm/ADT/SetVector.h"
Eli Friedman911e12f2011-07-20 21:57:23 +000016#include "llvm/Analysis/ConstantFolding.h"
Craig Topperb45eabc2017-04-26 16:39:58 +000017#include "llvm/Analysis/TargetLibraryInfo.h"
Chandler Carruth9fb823b2013-01-02 11:36:10 +000018#include "llvm/IR/DataLayout.h"
Vedant Kumare48597a2018-01-26 22:02:52 +000019#include "llvm/IR/DIBuilder.h"
Chandler Carruth820a9082014-03-04 11:08:18 +000020#include "llvm/IR/PatternMatch.h"
Craig Topperb45eabc2017-04-26 16:39:58 +000021#include "llvm/Support/KnownBits.h"
Chris Lattner2b295a02010-01-04 07:53:58 +000022using namespace llvm;
23using namespace PatternMatch;
24
Chandler Carruth964daaa2014-04-22 02:55:47 +000025#define DEBUG_TYPE "instcombine"
26
Sanjay Patel2fbab9d82015-09-09 14:34:26 +000027/// Analyze 'Val', seeing if it is a simple linear expression.
28/// If so, decompose it, returning some value X, such that Val is
Chris Lattner59d95742010-01-04 07:59:07 +000029/// X*Scale+Offset.
30///
Sanjay Patele2834412015-09-09 14:54:29 +000031static Value *decomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
Dan Gohman05a65552010-05-28 04:33:04 +000032 uint64_t &Offset) {
Chris Lattner59d95742010-01-04 07:59:07 +000033 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
34 Offset = CI->getZExtValue();
35 Scale = 0;
Dan Gohman05a65552010-05-28 04:33:04 +000036 return ConstantInt::get(Val->getType(), 0);
Chris Lattneraaccc8d2010-01-05 20:57:30 +000037 }
Craig Topper3529aa52013-01-24 05:22:40 +000038
Chris Lattneraaccc8d2010-01-05 20:57:30 +000039 if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
Bob Wilson3c68b622011-07-08 22:09:33 +000040 // Cannot look past anything that might overflow.
41 OverflowingBinaryOperator *OBI = dyn_cast<OverflowingBinaryOperator>(Val);
Stepan Dyatkovskiycb2a1a32012-05-05 07:09:40 +000042 if (OBI && !OBI->hasNoUnsignedWrap() && !OBI->hasNoSignedWrap()) {
Bob Wilson3c68b622011-07-08 22:09:33 +000043 Scale = 1;
44 Offset = 0;
45 return Val;
46 }
47
Chris Lattner59d95742010-01-04 07:59:07 +000048 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
49 if (I->getOpcode() == Instruction::Shl) {
50 // This is a value scaled by '1 << the shift amt'.
Dan Gohman05a65552010-05-28 04:33:04 +000051 Scale = UINT64_C(1) << RHS->getZExtValue();
Chris Lattner59d95742010-01-04 07:59:07 +000052 Offset = 0;
53 return I->getOperand(0);
Chris Lattneraaccc8d2010-01-05 20:57:30 +000054 }
Craig Topper3529aa52013-01-24 05:22:40 +000055
Chris Lattneraaccc8d2010-01-05 20:57:30 +000056 if (I->getOpcode() == Instruction::Mul) {
Chris Lattner59d95742010-01-04 07:59:07 +000057 // This value is scaled by 'RHS'.
58 Scale = RHS->getZExtValue();
59 Offset = 0;
60 return I->getOperand(0);
Chris Lattneraaccc8d2010-01-05 20:57:30 +000061 }
Craig Topper3529aa52013-01-24 05:22:40 +000062
Chris Lattneraaccc8d2010-01-05 20:57:30 +000063 if (I->getOpcode() == Instruction::Add) {
Craig Topper3529aa52013-01-24 05:22:40 +000064 // We have X+C. Check to see if we really have (X*C2)+C1,
Chris Lattner59d95742010-01-04 07:59:07 +000065 // where C1 is divisible by C2.
66 unsigned SubScale;
Craig Topper3529aa52013-01-24 05:22:40 +000067 Value *SubVal =
Sanjay Patele2834412015-09-09 14:54:29 +000068 decomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
Chris Lattner59d95742010-01-04 07:59:07 +000069 Offset += RHS->getZExtValue();
70 Scale = SubScale;
71 return SubVal;
72 }
73 }
74 }
75
76 // Otherwise, we can't look past this.
77 Scale = 1;
78 Offset = 0;
79 return Val;
80}
81
Sanjay Patel2fbab9d82015-09-09 14:34:26 +000082/// If we find a cast of an allocation instruction, try to eliminate the cast by
83/// moving the type information into the alloc.
Chris Lattner59d95742010-01-04 07:59:07 +000084Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
85 AllocaInst &AI) {
Chris Lattner229907c2011-07-18 04:54:35 +000086 PointerType *PTy = cast<PointerType>(CI.getType());
Craig Topper3529aa52013-01-24 05:22:40 +000087
Craig Topperbb4069e2017-07-07 23:16:26 +000088 BuilderTy AllocaBuilder(Builder);
Duncan P. N. Exon Smith9f8aaf22015-10-13 16:59:33 +000089 AllocaBuilder.SetInsertPoint(&AI);
Chris Lattner59d95742010-01-04 07:59:07 +000090
91 // Get the type really allocated and the type casted to.
Chris Lattner229907c2011-07-18 04:54:35 +000092 Type *AllocElTy = AI.getAllocatedType();
93 Type *CastElTy = PTy->getElementType();
Craig Topperf40110f2014-04-25 05:29:35 +000094 if (!AllocElTy->isSized() || !CastElTy->isSized()) return nullptr;
Chris Lattner59d95742010-01-04 07:59:07 +000095
Mehdi Aminia28d91d2015-03-10 02:37:25 +000096 unsigned AllocElTyAlign = DL.getABITypeAlignment(AllocElTy);
97 unsigned CastElTyAlign = DL.getABITypeAlignment(CastElTy);
Craig Topperf40110f2014-04-25 05:29:35 +000098 if (CastElTyAlign < AllocElTyAlign) return nullptr;
Chris Lattner59d95742010-01-04 07:59:07 +000099
100 // If the allocation has multiple uses, only promote it if we are strictly
101 // increasing the alignment of the resultant allocation. If we keep it the
Devang Patelfbb482b2011-03-08 22:12:11 +0000102 // same, we open the door to infinite loops of various kinds.
Craig Topperf40110f2014-04-25 05:29:35 +0000103 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return nullptr;
Chris Lattner59d95742010-01-04 07:59:07 +0000104
Mehdi Aminia28d91d2015-03-10 02:37:25 +0000105 uint64_t AllocElTySize = DL.getTypeAllocSize(AllocElTy);
106 uint64_t CastElTySize = DL.getTypeAllocSize(CastElTy);
Craig Topperf40110f2014-04-25 05:29:35 +0000107 if (CastElTySize == 0 || AllocElTySize == 0) return nullptr;
Chris Lattner59d95742010-01-04 07:59:07 +0000108
Jim Grosbach95d2eb92013-03-06 05:44:53 +0000109 // If the allocation has multiple uses, only promote it if we're not
110 // shrinking the amount of memory being allocated.
Mehdi Aminia28d91d2015-03-10 02:37:25 +0000111 uint64_t AllocElTyStoreSize = DL.getTypeStoreSize(AllocElTy);
112 uint64_t CastElTyStoreSize = DL.getTypeStoreSize(CastElTy);
Craig Topperf40110f2014-04-25 05:29:35 +0000113 if (!AI.hasOneUse() && CastElTyStoreSize < AllocElTyStoreSize) return nullptr;
Jim Grosbach95d2eb92013-03-06 05:44:53 +0000114
Chris Lattner59d95742010-01-04 07:59:07 +0000115 // See if we can satisfy the modulus by pulling a scale out of the array
116 // size argument.
117 unsigned ArraySizeScale;
Dan Gohman05a65552010-05-28 04:33:04 +0000118 uint64_t ArrayOffset;
Chris Lattner59d95742010-01-04 07:59:07 +0000119 Value *NumElements = // See if the array size is a decomposable linear expr.
Sanjay Patele2834412015-09-09 14:54:29 +0000120 decomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
Craig Topper3529aa52013-01-24 05:22:40 +0000121
Chris Lattner59d95742010-01-04 07:59:07 +0000122 // If we can now satisfy the modulus, by using a non-1 scale, we really can
123 // do the xform.
124 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
Craig Topperf40110f2014-04-25 05:29:35 +0000125 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return nullptr;
Chris Lattner59d95742010-01-04 07:59:07 +0000126
127 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
Craig Topperf40110f2014-04-25 05:29:35 +0000128 Value *Amt = nullptr;
Chris Lattner59d95742010-01-04 07:59:07 +0000129 if (Scale == 1) {
130 Amt = NumElements;
131 } else {
Dan Gohman05a65552010-05-28 04:33:04 +0000132 Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale);
Chris Lattner59d95742010-01-04 07:59:07 +0000133 // Insert before the alloca, not before the cast.
Benjamin Kramer547b6c52011-09-27 20:39:19 +0000134 Amt = AllocaBuilder.CreateMul(Amt, NumElements);
Chris Lattner59d95742010-01-04 07:59:07 +0000135 }
Craig Topper3529aa52013-01-24 05:22:40 +0000136
Dan Gohman05a65552010-05-28 04:33:04 +0000137 if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
138 Value *Off = ConstantInt::get(AI.getArraySize()->getType(),
Chris Lattner59d95742010-01-04 07:59:07 +0000139 Offset, true);
Benjamin Kramer547b6c52011-09-27 20:39:19 +0000140 Amt = AllocaBuilder.CreateAdd(Amt, Off);
Chris Lattner59d95742010-01-04 07:59:07 +0000141 }
Craig Topper3529aa52013-01-24 05:22:40 +0000142
Chris Lattner59d95742010-01-04 07:59:07 +0000143 AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
144 New->setAlignment(AI.getAlignment());
145 New->takeName(&AI);
Hans Wennborge36e1162014-04-28 17:40:03 +0000146 New->setUsedWithInAlloca(AI.isUsedWithInAlloca());
Craig Topper3529aa52013-01-24 05:22:40 +0000147
Chris Lattner59d95742010-01-04 07:59:07 +0000148 // If the allocation has multiple real uses, insert a cast and change all
149 // things that used it to use the new cast. This will also hack on CI, but it
150 // will die soon.
Devang Patelfbb482b2011-03-08 22:12:11 +0000151 if (!AI.hasOneUse()) {
Chris Lattner59d95742010-01-04 07:59:07 +0000152 // New is the allocation instruction, pointer typed. AI is the original
153 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
154 Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
Sanjay Patel4b198802016-02-01 22:23:39 +0000155 replaceInstUsesWith(AI, NewCast);
Chris Lattner59d95742010-01-04 07:59:07 +0000156 }
Sanjay Patel4b198802016-02-01 22:23:39 +0000157 return replaceInstUsesWith(CI, New);
Chris Lattner59d95742010-01-04 07:59:07 +0000158}
159
Sanjay Patel2fbab9d82015-09-09 14:34:26 +0000160/// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns
161/// true for, actually insert the code to evaluate the expression.
Craig Topper3529aa52013-01-24 05:22:40 +0000162Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty,
Chris Lattner92be2ad2010-01-04 07:54:59 +0000163 bool isSigned) {
Chris Lattner9242ae02010-01-08 19:28:47 +0000164 if (Constant *C = dyn_cast<Constant>(V)) {
165 C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
Rafael Espindola37dc9e12014-02-21 00:06:31 +0000166 // If we got a constantexpr back, try to simplify it with DL info.
Justin Bogner99798402016-08-05 01:06:44 +0000167 if (Constant *FoldedC = ConstantFoldConstant(C, DL, &TLI))
David Majnemerd536f232016-07-29 03:27:26 +0000168 C = FoldedC;
Chris Lattner9242ae02010-01-08 19:28:47 +0000169 return C;
170 }
Chris Lattner92be2ad2010-01-04 07:54:59 +0000171
172 // Otherwise, it must be an instruction.
173 Instruction *I = cast<Instruction>(V);
Craig Topperf40110f2014-04-25 05:29:35 +0000174 Instruction *Res = nullptr;
Chris Lattner92be2ad2010-01-04 07:54:59 +0000175 unsigned Opc = I->getOpcode();
176 switch (Opc) {
177 case Instruction::Add:
178 case Instruction::Sub:
179 case Instruction::Mul:
180 case Instruction::And:
181 case Instruction::Or:
182 case Instruction::Xor:
183 case Instruction::AShr:
184 case Instruction::LShr:
185 case Instruction::Shl:
186 case Instruction::UDiv:
187 case Instruction::URem: {
Sanjay Patel49aafec2018-02-05 21:50:32 +0000188 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
189 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
Chris Lattner92be2ad2010-01-04 07:54:59 +0000190 Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
191 break;
Craig Topper3529aa52013-01-24 05:22:40 +0000192 }
Chris Lattner92be2ad2010-01-04 07:54:59 +0000193 case Instruction::Trunc:
194 case Instruction::ZExt:
195 case Instruction::SExt:
196 // If the source type of the cast is the type we're trying for then we can
197 // just return the source. There's no need to insert it because it is not
198 // new.
199 if (I->getOperand(0)->getType() == Ty)
200 return I->getOperand(0);
Craig Topper3529aa52013-01-24 05:22:40 +0000201
Chris Lattner92be2ad2010-01-04 07:54:59 +0000202 // Otherwise, must be the same type of cast, so just reinsert a new one.
Chris Lattner39d2daa2010-01-10 20:25:54 +0000203 // This also handles the case of zext(trunc(x)) -> zext(x).
204 Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
205 Opc == Instruction::SExt);
Chris Lattner92be2ad2010-01-04 07:54:59 +0000206 break;
207 case Instruction::Select: {
208 Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
209 Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
210 Res = SelectInst::Create(I->getOperand(0), True, False);
211 break;
212 }
213 case Instruction::PHI: {
214 PHINode *OPN = cast<PHINode>(I);
Jay Foad52131342011-03-30 11:28:46 +0000215 PHINode *NPN = PHINode::Create(Ty, OPN->getNumIncomingValues());
Chris Lattner92be2ad2010-01-04 07:54:59 +0000216 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
Mehdi Aminia28d91d2015-03-10 02:37:25 +0000217 Value *V =
218 EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
Chris Lattner92be2ad2010-01-04 07:54:59 +0000219 NPN->addIncoming(V, OPN->getIncomingBlock(i));
220 }
221 Res = NPN;
222 break;
223 }
Craig Topper3529aa52013-01-24 05:22:40 +0000224 default:
Chris Lattner92be2ad2010-01-04 07:54:59 +0000225 // TODO: Can handle more cases here.
226 llvm_unreachable("Unreachable!");
Chris Lattner92be2ad2010-01-04 07:54:59 +0000227 }
Craig Topper3529aa52013-01-24 05:22:40 +0000228
Chris Lattner92be2ad2010-01-04 07:54:59 +0000229 Res->takeName(I);
Eli Friedman35211c62011-05-27 00:19:40 +0000230 return InsertNewInstWith(Res, *I);
Chris Lattner92be2ad2010-01-04 07:54:59 +0000231}
Chris Lattner2b295a02010-01-04 07:53:58 +0000232
Tobias Grosser8ef834c2016-07-19 09:06:08 +0000233Instruction::CastOps InstCombiner::isEliminableCastPair(const CastInst *CI1,
234 const CastInst *CI2) {
235 Type *SrcTy = CI1->getSrcTy();
236 Type *MidTy = CI1->getDestTy();
237 Type *DstTy = CI2->getDestTy();
Chris Lattner2b295a02010-01-04 07:53:58 +0000238
Craig Toppera86ca082017-08-04 05:12:35 +0000239 Instruction::CastOps firstOp = CI1->getOpcode();
240 Instruction::CastOps secondOp = CI2->getOpcode();
Mehdi Aminia28d91d2015-03-10 02:37:25 +0000241 Type *SrcIntPtrTy =
242 SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr;
243 Type *MidIntPtrTy =
244 MidTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(MidTy) : nullptr;
245 Type *DstIntPtrTy =
246 DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +0000247 unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
Duncan Sandse2395dc2012-10-30 16:03:32 +0000248 DstTy, SrcIntPtrTy, MidIntPtrTy,
249 DstIntPtrTy);
Micah Villmow12d91272012-10-24 15:52:52 +0000250
Chris Lattner2b295a02010-01-04 07:53:58 +0000251 // We don't want to form an inttoptr or ptrtoint that converts to an integer
252 // type that differs from the pointer size.
Duncan Sandse2395dc2012-10-30 16:03:32 +0000253 if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
254 (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
Chris Lattner2b295a02010-01-04 07:53:58 +0000255 Res = 0;
Craig Topper3529aa52013-01-24 05:22:40 +0000256
Chris Lattner2b295a02010-01-04 07:53:58 +0000257 return Instruction::CastOps(Res);
258}
259
Adrian Prantl4dfcc4a2018-05-01 16:10:38 +0000260/// Implement the transforms common to all CastInst visitors.
Chris Lattner2b295a02010-01-04 07:53:58 +0000261Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
262 Value *Src = CI.getOperand(0);
263
Sanjay Patel8d7196b2016-10-26 14:52:35 +0000264 // Try to eliminate a cast of a cast.
265 if (auto *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
266 if (Instruction::CastOps NewOpc = isEliminableCastPair(CSrc, &CI)) {
Chris Lattner2b295a02010-01-04 07:53:58 +0000267 // The first cast (CSrc) is eliminable so we need to fix up or replace
268 // the second cast (CI). CSrc will then have a good chance of being dead.
Vedant Kumarf6c0b412018-06-27 00:47:53 +0000269 auto *Ty = CI.getType();
270 auto *Res = CastInst::Create(NewOpc, CSrc->getOperand(0), Ty);
Vedant Kumar6379a622018-07-06 17:32:39 +0000271 // Point debug users of the dying cast to the new one.
272 if (CSrc->hasOneUse())
273 replaceAllDbgUsesWith(*CSrc, *Res, CI, DT);
Vedant Kumare48597a2018-01-26 22:02:52 +0000274 return Res;
Chris Lattner2b295a02010-01-04 07:53:58 +0000275 }
276 }
277
Sanjay Patele5bc4412018-05-31 00:16:58 +0000278 if (auto *Sel = dyn_cast<SelectInst>(Src)) {
279 // We are casting a select. Try to fold the cast into the select, but only
280 // if the select does not have a compare instruction with matching operand
281 // types. Creating a select with operands that are different sizes than its
282 // condition may inhibit other folds and lead to worse codegen.
283 auto *Cmp = dyn_cast<CmpInst>(Sel->getCondition());
284 if (!Cmp || Cmp->getOperand(0)->getType() != Sel->getType())
Vedant Kumar9ece8182018-07-17 18:08:36 +0000285 if (Instruction *NV = FoldOpIntoSelect(CI, Sel)) {
286 replaceAllDbgUsesWith(*Sel, *NV, CI, DT);
Sanjay Patele5bc4412018-05-31 00:16:58 +0000287 return NV;
Vedant Kumar9ece8182018-07-17 18:08:36 +0000288 }
Sanjay Patele5bc4412018-05-31 00:16:58 +0000289 }
Chris Lattner2b295a02010-01-04 07:53:58 +0000290
Sanjay Patel8d7196b2016-10-26 14:52:35 +0000291 // If we are casting a PHI, then fold the cast into the PHI.
Craig Topperfb71b7d2017-04-14 19:20:12 +0000292 if (auto *PN = dyn_cast<PHINode>(Src)) {
Sanjay Patel8d7196b2016-10-26 14:52:35 +0000293 // Don't do this if it would create a PHI node with an illegal type from a
294 // legal type.
Mehdi Aminia28d91d2015-03-10 02:37:25 +0000295 if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() ||
Sanjay Patel2217f752017-01-31 17:25:42 +0000296 shouldChangeType(CI.getType(), Src->getType()))
Craig Topperfb71b7d2017-04-14 19:20:12 +0000297 if (Instruction *NV = foldOpIntoPhi(CI, PN))
Chris Lattner2b295a02010-01-04 07:53:58 +0000298 return NV;
299 }
Craig Topper3529aa52013-01-24 05:22:40 +0000300
Craig Topperf40110f2014-04-25 05:29:35 +0000301 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +0000302}
303
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000304/// Constants and extensions/truncates from the destination type are always
305/// free to be evaluated in that type. This is a helper for canEvaluate*.
306static bool canAlwaysEvaluateInType(Value *V, Type *Ty) {
307 if (isa<Constant>(V))
308 return true;
309 Value *X;
310 if ((match(V, m_ZExtOrSExt(m_Value(X))) || match(V, m_Trunc(m_Value(X)))) &&
311 X->getType() == Ty)
312 return true;
313
314 return false;
315}
316
317/// Filter out values that we can not evaluate in the destination type for free.
318/// This is a helper for canEvaluate*.
319static bool canNotEvaluateInType(Value *V, Type *Ty) {
320 assert(!isa<Constant>(V) && "Constant should already be handled.");
321 if (!isa<Instruction>(V))
322 return true;
Sanjay Patel49aafec2018-02-05 21:50:32 +0000323 // We don't extend or shrink something that has multiple uses -- doing so
324 // would require duplicating the instruction which isn't profitable.
325 if (!V->hasOneUse())
326 return true;
327
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000328 return false;
329}
330
Sanjay Patel2fbab9d82015-09-09 14:34:26 +0000331/// Return true if we can evaluate the specified expression tree as type Ty
332/// instead of its larger type, and arrive with the same value.
333/// This is used by code that tries to eliminate truncates.
Chris Lattnerc3aca382010-01-10 00:58:42 +0000334///
335/// Ty will always be a type smaller than V. We should return true if trunc(V)
336/// can be computed by computing V in the smaller type. If V is an instruction,
337/// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
338/// makes sense if x and y can be efficiently truncated.
339///
Chris Lattner172630a2010-01-11 02:43:35 +0000340/// This function works on both vectors and scalars.
341///
Sanjay Patele2834412015-09-09 14:54:29 +0000342static bool canEvaluateTruncated(Value *V, Type *Ty, InstCombiner &IC,
Hal Finkel60db0582014-09-07 18:57:58 +0000343 Instruction *CxtI) {
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000344 if (canAlwaysEvaluateInType(V, Ty))
Chris Lattnerc3aca382010-01-10 00:58:42 +0000345 return true;
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000346 if (canNotEvaluateInType(V, Ty))
347 return false;
Craig Topper3529aa52013-01-24 05:22:40 +0000348
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000349 auto *I = cast<Instruction>(V);
Chris Lattner229907c2011-07-18 04:54:35 +0000350 Type *OrigTy = V->getType();
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000351 switch (I->getOpcode()) {
Chris Lattnerc3aca382010-01-10 00:58:42 +0000352 case Instruction::Add:
353 case Instruction::Sub:
354 case Instruction::Mul:
355 case Instruction::And:
356 case Instruction::Or:
357 case Instruction::Xor:
358 // These operators can all arbitrarily be extended or truncated.
Sanjay Patele2834412015-09-09 14:54:29 +0000359 return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
360 canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
Chris Lattnerc3aca382010-01-10 00:58:42 +0000361
362 case Instruction::UDiv:
363 case Instruction::URem: {
364 // UDiv and URem can be truncated if all the truncated bits are zero.
365 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
366 uint32_t BitWidth = Ty->getScalarSizeInBits();
Craig Topperea78a262018-05-10 22:45:28 +0000367 assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
368 APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
369 if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) &&
370 IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) {
371 return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
372 canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
Chris Lattnerc3aca382010-01-10 00:58:42 +0000373 }
374 break;
375 }
Craig Topper0a1a2762017-08-15 22:48:41 +0000376 case Instruction::Shl: {
Chris Lattnerc3aca382010-01-10 00:58:42 +0000377 // If we are truncating the result of this SHL, and if it's a shift of a
378 // constant amount, we can always perform a SHL in a smaller type.
Craig Topper0a1a2762017-08-15 22:48:41 +0000379 const APInt *Amt;
380 if (match(I->getOperand(1), m_APInt(Amt))) {
Chris Lattnerc3aca382010-01-10 00:58:42 +0000381 uint32_t BitWidth = Ty->getScalarSizeInBits();
Craig Topper0a1a2762017-08-15 22:48:41 +0000382 if (Amt->getLimitedValue(BitWidth) < BitWidth)
Sanjay Patele2834412015-09-09 14:54:29 +0000383 return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
Chris Lattnerc3aca382010-01-10 00:58:42 +0000384 }
385 break;
Craig Topper0a1a2762017-08-15 22:48:41 +0000386 }
387 case Instruction::LShr: {
Chris Lattnerc3aca382010-01-10 00:58:42 +0000388 // If this is a truncate of a logical shr, we can truncate it to a smaller
Sylvestre Ledru91ce36c2012-09-27 10:14:43 +0000389 // lshr iff we know that the bits we would otherwise be shifting in are
Chris Lattnerc3aca382010-01-10 00:58:42 +0000390 // already zeros.
Craig Topper0a1a2762017-08-15 22:48:41 +0000391 const APInt *Amt;
392 if (match(I->getOperand(1), m_APInt(Amt))) {
Chris Lattnerc3aca382010-01-10 00:58:42 +0000393 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
394 uint32_t BitWidth = Ty->getScalarSizeInBits();
Craig Topper553d4512018-05-10 00:53:25 +0000395 if (Amt->getLimitedValue(BitWidth) < BitWidth &&
396 IC.MaskedValueIsZero(I->getOperand(0),
397 APInt::getBitsSetFrom(OrigBitWidth, BitWidth), 0, CxtI)) {
Sanjay Patele2834412015-09-09 14:54:29 +0000398 return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
Chris Lattnerc3aca382010-01-10 00:58:42 +0000399 }
400 }
401 break;
Craig Topper0a1a2762017-08-15 22:48:41 +0000402 }
Amjad Aboud86111c62017-08-16 22:42:38 +0000403 case Instruction::AShr: {
404 // If this is a truncate of an arithmetic shr, we can truncate it to a
405 // smaller ashr iff we know that all the bits from the sign bit of the
406 // original type and the sign bit of the truncate type are similar.
407 // TODO: It is enough to check that the bits we would be shifting in are
408 // similar to sign bit of the truncate type.
409 const APInt *Amt;
410 if (match(I->getOperand(1), m_APInt(Amt))) {
411 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
412 uint32_t BitWidth = Ty->getScalarSizeInBits();
413 if (Amt->getLimitedValue(BitWidth) < BitWidth &&
414 OrigBitWidth - BitWidth <
415 IC.ComputeNumSignBits(I->getOperand(0), 0, CxtI))
416 return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI);
417 }
418 break;
419 }
Chris Lattnerc3aca382010-01-10 00:58:42 +0000420 case Instruction::Trunc:
421 // trunc(trunc(x)) -> trunc(x)
422 return true;
Chris Lattner73984342010-08-27 20:32:06 +0000423 case Instruction::ZExt:
424 case Instruction::SExt:
425 // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
426 // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
427 return true;
Chris Lattnerc3aca382010-01-10 00:58:42 +0000428 case Instruction::Select: {
429 SelectInst *SI = cast<SelectInst>(I);
Sanjay Patele2834412015-09-09 14:54:29 +0000430 return canEvaluateTruncated(SI->getTrueValue(), Ty, IC, CxtI) &&
431 canEvaluateTruncated(SI->getFalseValue(), Ty, IC, CxtI);
Chris Lattnerc3aca382010-01-10 00:58:42 +0000432 }
433 case Instruction::PHI: {
434 // We can change a phi if we can change all operands. Note that we never
435 // get into trouble with cyclic PHIs here because we only consider
436 // instructions with a single use.
437 PHINode *PN = cast<PHINode>(I);
Pete Cooper833f34d2015-05-12 20:05:31 +0000438 for (Value *IncValue : PN->incoming_values())
Sanjay Patele2834412015-09-09 14:54:29 +0000439 if (!canEvaluateTruncated(IncValue, Ty, IC, CxtI))
Chris Lattnerc3aca382010-01-10 00:58:42 +0000440 return false;
441 return true;
442 }
443 default:
444 // TODO: Can handle more cases here.
445 break;
446 }
Craig Topper3529aa52013-01-24 05:22:40 +0000447
Chris Lattnerc3aca382010-01-10 00:58:42 +0000448 return false;
449}
450
Sanjay Patelf727e382015-12-14 16:16:54 +0000451/// Given a vector that is bitcast to an integer, optionally logically
452/// right-shifted, and truncated, convert it to an extractelement.
453/// Example (big endian):
454/// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32
455/// --->
456/// extractelement <4 x i32> %X, 1
Craig Toppercb220392017-07-06 23:18:43 +0000457static Instruction *foldVecTruncToExtElt(TruncInst &Trunc, InstCombiner &IC) {
Sanjay Patelf727e382015-12-14 16:16:54 +0000458 Value *TruncOp = Trunc.getOperand(0);
459 Type *DestType = Trunc.getType();
460 if (!TruncOp->hasOneUse() || !isa<IntegerType>(DestType))
461 return nullptr;
462
463 Value *VecInput = nullptr;
464 ConstantInt *ShiftVal = nullptr;
465 if (!match(TruncOp, m_CombineOr(m_BitCast(m_Value(VecInput)),
466 m_LShr(m_BitCast(m_Value(VecInput)),
467 m_ConstantInt(ShiftVal)))) ||
468 !isa<VectorType>(VecInput->getType()))
469 return nullptr;
470
471 VectorType *VecType = cast<VectorType>(VecInput->getType());
472 unsigned VecWidth = VecType->getPrimitiveSizeInBits();
473 unsigned DestWidth = DestType->getPrimitiveSizeInBits();
474 unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0;
475
476 if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0))
477 return nullptr;
478
479 // If the element type of the vector doesn't match the result type,
480 // bitcast it to a vector type that we can extract from.
481 unsigned NumVecElts = VecWidth / DestWidth;
482 if (VecType->getElementType() != DestType) {
483 VecType = VectorType::get(DestType, NumVecElts);
Craig Topperbb4069e2017-07-07 23:16:26 +0000484 VecInput = IC.Builder.CreateBitCast(VecInput, VecType, "bc");
Sanjay Patelf727e382015-12-14 16:16:54 +0000485 }
486
487 unsigned Elt = ShiftAmount / DestWidth;
Craig Toppercb220392017-07-06 23:18:43 +0000488 if (IC.getDataLayout().isBigEndian())
Sanjay Patelf727e382015-12-14 16:16:54 +0000489 Elt = NumVecElts - 1 - Elt;
490
Craig Topperbb4069e2017-07-07 23:16:26 +0000491 return ExtractElementInst::Create(VecInput, IC.Builder.getInt32(Elt));
Sanjay Patelf727e382015-12-14 16:16:54 +0000492}
493
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000494/// Rotate left/right may occur in a wider type than necessary because of type
Sanjay Patel722466e2019-01-04 17:38:12 +0000495/// promotion rules. Try to narrow the inputs and convert to funnel shift.
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000496Instruction *InstCombiner::narrowRotate(TruncInst &Trunc) {
497 assert((isa<VectorType>(Trunc.getSrcTy()) ||
498 shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) &&
499 "Don't narrow to an illegal scalar type");
500
Sanjay Patelbc56b242018-11-15 17:19:14 +0000501 // Bail out on strange types. It is possible to handle some of these patterns
502 // even with non-power-of-2 sizes, but it is not a likely scenario.
503 Type *DestTy = Trunc.getType();
504 unsigned NarrowWidth = DestTy->getScalarSizeInBits();
505 if (!isPowerOf2_32(NarrowWidth))
506 return nullptr;
507
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000508 // First, find an or'd pair of opposite shifts with the same shifted operand:
509 // trunc (or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1))
510 Value *Or0, *Or1;
511 if (!match(Trunc.getOperand(0), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1)))))
512 return nullptr;
513
514 Value *ShVal, *ShAmt0, *ShAmt1;
515 if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) ||
516 !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1)))))
517 return nullptr;
518
519 auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
520 auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
521 if (ShiftOpcode0 == ShiftOpcode1)
522 return nullptr;
523
Sanjay Patelceab2322018-11-12 22:00:00 +0000524 // Match the shift amount operands for a rotate pattern. This always matches
525 // a subtraction on the R operand.
526 auto matchShiftAmount = [](Value *L, Value *R, unsigned Width) -> Value * {
527 // The shift amounts may add up to the narrow bit width:
528 // (shl ShVal, L) | (lshr ShVal, Width - L)
529 if (match(R, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(L)))))
530 return L;
531
Sanjay Patel98e427c2018-11-12 22:11:09 +0000532 // The shift amount may be masked with negation:
533 // (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1)))
534 Value *X;
535 unsigned Mask = Width - 1;
536 if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) &&
537 match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))
538 return X;
539
Sanjay Patel35b1c2d2018-11-12 22:52:25 +0000540 // Same as above, but the shift amount may be extended after masking:
541 if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
542 match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))))
543 return X;
544
Sanjay Patelceab2322018-11-12 22:00:00 +0000545 return nullptr;
546 };
547
Sanjay Patelceab2322018-11-12 22:00:00 +0000548 Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth);
549 bool SubIsOnLHS = false;
550 if (!ShAmt) {
551 ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth);
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000552 SubIsOnLHS = true;
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000553 }
Sanjay Patelceab2322018-11-12 22:00:00 +0000554 if (!ShAmt)
555 return nullptr;
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000556
557 // The shifted value must have high zeros in the wide type. Typically, this
558 // will be a zext, but it could also be the result of an 'and' or 'shift'.
559 unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits();
560 APInt HiBitMask = APInt::getHighBitsSet(WideWidth, WideWidth - NarrowWidth);
561 if (!MaskedValueIsZero(ShVal, HiBitMask, 0, &Trunc))
562 return nullptr;
563
564 // We have an unnecessarily wide rotate!
565 // trunc (or (lshr ShVal, ShAmt), (shl ShVal, BitWidth - ShAmt))
Sanjay Patel722466e2019-01-04 17:38:12 +0000566 // Narrow the inputs and convert to funnel shift intrinsic:
567 // llvm.fshl.i8(trunc(ShVal), trunc(ShVal), trunc(ShAmt))
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000568 Value *NarrowShAmt = Builder.CreateTrunc(ShAmt, DestTy);
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000569 Value *X = Builder.CreateTrunc(ShVal, DestTy);
Sanjay Patel722466e2019-01-04 17:38:12 +0000570 bool IsFshl = (!SubIsOnLHS && ShiftOpcode0 == BinaryOperator::Shl) ||
571 (SubIsOnLHS && ShiftOpcode1 == BinaryOperator::Shl);
572 Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
573 Function *F = Intrinsic::getDeclaration(Trunc.getModule(), IID, DestTy);
574 return IntrinsicInst::Create(F, { X, X, NarrowShAmt });
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000575}
576
Sanjay Patel94da1de2017-08-05 15:19:18 +0000577/// Try to narrow the width of math or bitwise logic instructions by pulling a
578/// truncate ahead of binary operators.
579/// TODO: Transforms for truncated shifts should be moved into here.
580Instruction *InstCombiner::narrowBinOp(TruncInst &Trunc) {
Sanjay Patelaa8b28e2016-11-30 20:48:54 +0000581 Type *SrcTy = Trunc.getSrcTy();
582 Type *DestTy = Trunc.getType();
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000583 if (!isa<VectorType>(SrcTy) && !shouldChangeType(SrcTy, DestTy))
Sanjay Patelaa8b28e2016-11-30 20:48:54 +0000584 return nullptr;
585
Sanjay Patel94da1de2017-08-05 15:19:18 +0000586 BinaryOperator *BinOp;
587 if (!match(Trunc.getOperand(0), m_OneUse(m_BinOp(BinOp))))
Sanjay Patelaa8b28e2016-11-30 20:48:54 +0000588 return nullptr;
589
Sanjay Patel03d0cd62017-11-15 19:12:01 +0000590 Value *BinOp0 = BinOp->getOperand(0);
591 Value *BinOp1 = BinOp->getOperand(1);
Sanjay Patel94da1de2017-08-05 15:19:18 +0000592 switch (BinOp->getOpcode()) {
593 case Instruction::And:
594 case Instruction::Or:
595 case Instruction::Xor:
596 case Instruction::Add:
Sanjay Patelb3fa9452017-11-16 14:40:51 +0000597 case Instruction::Sub:
Sanjay Patel94da1de2017-08-05 15:19:18 +0000598 case Instruction::Mul: {
599 Constant *C;
Sanjay Patelb3fa9452017-11-16 14:40:51 +0000600 if (match(BinOp0, m_Constant(C))) {
601 // trunc (binop C, X) --> binop (trunc C', X)
602 Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
603 Value *TruncX = Builder.CreateTrunc(BinOp1, DestTy);
604 return BinaryOperator::Create(BinOp->getOpcode(), NarrowC, TruncX);
605 }
Sanjay Patel03d0cd62017-11-15 19:12:01 +0000606 if (match(BinOp1, m_Constant(C))) {
Sanjay Patel94da1de2017-08-05 15:19:18 +0000607 // trunc (binop X, C) --> binop (trunc X, C')
608 Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
Sanjay Patel03d0cd62017-11-15 19:12:01 +0000609 Value *TruncX = Builder.CreateTrunc(BinOp0, DestTy);
Sanjay Patel94da1de2017-08-05 15:19:18 +0000610 return BinaryOperator::Create(BinOp->getOpcode(), TruncX, NarrowC);
611 }
Sanjay Patel03d0cd62017-11-15 19:12:01 +0000612 Value *X;
613 if (match(BinOp0, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
614 // trunc (binop (ext X), Y) --> binop X, (trunc Y)
615 Value *NarrowOp1 = Builder.CreateTrunc(BinOp1, DestTy);
616 return BinaryOperator::Create(BinOp->getOpcode(), X, NarrowOp1);
617 }
618 if (match(BinOp1, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) {
619 // trunc (binop Y, (ext X)) --> binop (trunc Y), X
620 Value *NarrowOp0 = Builder.CreateTrunc(BinOp0, DestTy);
621 return BinaryOperator::Create(BinOp->getOpcode(), NarrowOp0, X);
622 }
Sanjay Patel94da1de2017-08-05 15:19:18 +0000623 break;
624 }
Sanjay Patel94da1de2017-08-05 15:19:18 +0000625
626 default: break;
627 }
628
Sanjay Patelc50e55d2017-08-09 18:37:41 +0000629 if (Instruction *NarrowOr = narrowRotate(Trunc))
630 return NarrowOr;
631
Sanjay Patel94da1de2017-08-05 15:19:18 +0000632 return nullptr;
Sanjay Patelaa8b28e2016-11-30 20:48:54 +0000633}
634
Sanjay Patel53fa17a2017-03-07 21:45:16 +0000635/// Try to narrow the width of a splat shuffle. This could be generalized to any
636/// shuffle with a constant operand, but we limit the transform to avoid
637/// creating a shuffle type that targets may not be able to lower effectively.
638static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
639 InstCombiner::BuilderTy &Builder) {
640 auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
641 if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
Sanjay Patel62906af2017-03-08 15:02:23 +0000642 Shuf->getMask()->getSplatValue() &&
643 Shuf->getType() == Shuf->getOperand(0)->getType()) {
Sanjay Patel53fa17a2017-03-07 21:45:16 +0000644 // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
645 Constant *NarrowUndef = UndefValue::get(Trunc.getType());
646 Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
647 return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
648 }
649
650 return nullptr;
651}
652
Sanjay Patelfe970512017-03-07 23:27:14 +0000653/// Try to narrow the width of an insert element. This could be generalized for
654/// any vector constant, but we limit the transform to insertion into undef to
655/// avoid potential backend problems from unsupported insertion widths. This
656/// could also be extended to handle the case of inserting a scalar constant
657/// into a vector variable.
658static Instruction *shrinkInsertElt(CastInst &Trunc,
659 InstCombiner::BuilderTy &Builder) {
660 Instruction::CastOps Opcode = Trunc.getOpcode();
661 assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
662 "Unexpected instruction for shrinking");
663
664 auto *InsElt = dyn_cast<InsertElementInst>(Trunc.getOperand(0));
665 if (!InsElt || !InsElt->hasOneUse())
666 return nullptr;
667
668 Type *DestTy = Trunc.getType();
669 Type *DestScalarTy = DestTy->getScalarType();
670 Value *VecOp = InsElt->getOperand(0);
671 Value *ScalarOp = InsElt->getOperand(1);
672 Value *Index = InsElt->getOperand(2);
673
674 if (isa<UndefValue>(VecOp)) {
675 // trunc (inselt undef, X, Index) --> inselt undef, (trunc X), Index
676 // fptrunc (inselt undef, X, Index) --> inselt undef, (fptrunc X), Index
677 UndefValue *NarrowUndef = UndefValue::get(DestTy);
678 Value *NarrowOp = Builder.CreateCast(Opcode, ScalarOp, DestScalarTy);
679 return InsertElementInst::Create(NarrowUndef, NarrowOp, Index);
680 }
681
682 return nullptr;
683}
684
Chris Lattnerc3aca382010-01-10 00:58:42 +0000685Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
Chris Lattner883550a2010-01-10 01:00:46 +0000686 if (Instruction *Result = commonCastTransforms(CI))
Chris Lattnerc3aca382010-01-10 00:58:42 +0000687 return Result;
Craig Topper3529aa52013-01-24 05:22:40 +0000688
Chris Lattnerc3aca382010-01-10 00:58:42 +0000689 Value *Src = CI.getOperand(0);
Chris Lattner229907c2011-07-18 04:54:35 +0000690 Type *DestTy = CI.getType(), *SrcTy = Src->getType();
Craig Topper3529aa52013-01-24 05:22:40 +0000691
Chris Lattnerc3aca382010-01-10 00:58:42 +0000692 // Attempt to truncate the entire input expression tree to the destination
693 // type. Only do this if the dest type is a simple type, don't convert the
Chris Lattner2b295a02010-01-04 07:53:58 +0000694 // expression tree to something weird like i93 unless the source is also
695 // strange.
Sanjay Patel2217f752017-01-31 17:25:42 +0000696 if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) &&
Sanjay Patele2834412015-09-09 14:54:29 +0000697 canEvaluateTruncated(Src, DestTy, *this, &CI)) {
Craig Topper3529aa52013-01-24 05:22:40 +0000698
Chris Lattner2b295a02010-01-04 07:53:58 +0000699 // If this cast is a truncate, evaluting in a different type always
Chris Lattner8600dd32010-01-05 23:00:30 +0000700 // eliminates the cast, so it is always a win.
Nicola Zaghend34e60c2018-05-14 12:53:11 +0000701 LLVM_DEBUG(
702 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
703 " to avoid cast: "
704 << CI << '\n');
Chris Lattner3057c372010-01-07 23:41:00 +0000705 Value *Res = EvaluateInDifferentType(Src, DestTy, false);
706 assert(Res->getType() == DestTy);
Sanjay Patel4b198802016-02-01 22:23:39 +0000707 return replaceInstUsesWith(CI, Res);
Chris Lattner3057c372010-01-07 23:41:00 +0000708 }
Chris Lattner2b295a02010-01-04 07:53:58 +0000709
Sanjay Patel9c2e7ce2018-07-04 17:44:04 +0000710 // Test if the trunc is the user of a select which is part of a
711 // minimum or maximum operation. If so, don't do any more simplification.
712 // Even simplifying demanded bits can break the canonical form of a
713 // min/max.
714 Value *LHS, *RHS;
715 if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
716 if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN)
717 return nullptr;
718
719 // See if we can simplify any instructions used by the input whose sole
720 // purpose is to compute bits we don't care about.
721 if (SimplifyDemandedInstructionBits(CI))
722 return &CI;
723
Chris Lattnera93c63c2010-01-05 22:21:18 +0000724 if (DestTy->getScalarSizeInBits() == 1) {
Chris Lattner2b295a02010-01-04 07:53:58 +0000725 Value *Zero = Constant::getNullValue(Src->getType());
Sanjay Patel05aadf82018-10-10 20:47:46 +0000726 if (DestTy->isIntegerTy()) {
727 // Canonicalize trunc x to i1 -> icmp ne (and x, 1), 0 (scalar only).
728 // TODO: We canonicalize to more instructions here because we are probably
729 // lacking equivalent analysis for trunc relative to icmp. There may also
730 // be codegen concerns. If those trunc limitations were removed, we could
731 // remove this transform.
732 Value *And = Builder.CreateAnd(Src, ConstantInt::get(SrcTy, 1));
733 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
734 }
735
736 // For vectors, we do not canonicalize all truncs to icmp, so optimize
737 // patterns that would be covered within visitICmpInst.
738 Value *X;
739 const APInt *C;
740 if (match(Src, m_OneUse(m_LShr(m_Value(X), m_APInt(C))))) {
741 // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0
742 APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C);
743 Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
744 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
745 }
746 if (match(Src, m_OneUse(m_c_Or(m_LShr(m_Value(X), m_APInt(C)),
747 m_Deferred(X))))) {
748 // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0
749 APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C) | 1;
750 Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC));
751 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
752 }
Chris Lattner2b295a02010-01-04 07:53:58 +0000753 }
Craig Topper3529aa52013-01-24 05:22:40 +0000754
Sanjay Patel6844e212017-05-09 16:24:59 +0000755 // FIXME: Maybe combine the next two transforms to handle the no cast case
756 // more efficiently. Support vector types. Cleanup code by using m_OneUse.
757
Chris Lattner90cd7462010-08-27 18:31:05 +0000758 // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
Craig Topperf40110f2014-04-25 05:29:35 +0000759 Value *A = nullptr; ConstantInt *Cst = nullptr;
Chris Lattner9c10d582011-01-15 06:32:33 +0000760 if (Src->hasOneUse() &&
761 match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
Chris Lattner90cd7462010-08-27 18:31:05 +0000762 // We have three types to worry about here, the type of A, the source of
763 // the truncate (MidSize), and the destination of the truncate. We know that
764 // ASize < MidSize and MidSize > ResultSize, but don't know the relation
765 // between ASize and ResultSize.
766 unsigned ASize = A->getType()->getPrimitiveSizeInBits();
Craig Topper3529aa52013-01-24 05:22:40 +0000767
Chris Lattner90cd7462010-08-27 18:31:05 +0000768 // If the shift amount is larger than the size of A, then the result is
769 // known to be zero because all the input bits got shifted out.
770 if (Cst->getZExtValue() >= ASize)
Sanjay Patel4b198802016-02-01 22:23:39 +0000771 return replaceInstUsesWith(CI, Constant::getNullValue(DestTy));
Chris Lattner90cd7462010-08-27 18:31:05 +0000772
773 // Since we're doing an lshr and a zero extend, and know that the shift
774 // amount is smaller than ASize, it is always safe to do the shift in A's
775 // type, then zero extend or truncate to the result.
Craig Topperbb4069e2017-07-07 23:16:26 +0000776 Value *Shift = Builder.CreateLShr(A, Cst->getZExtValue());
Chris Lattner90cd7462010-08-27 18:31:05 +0000777 Shift->takeName(Src);
Sanjay Patelf09d1bf2015-11-17 18:37:23 +0000778 return CastInst::CreateIntegerCast(Shift, DestTy, false);
Chris Lattner90cd7462010-08-27 18:31:05 +0000779 }
Craig Topper3529aa52013-01-24 05:22:40 +0000780
Davide Italiano21a49dc2017-05-21 20:30:27 +0000781 // FIXME: We should canonicalize to zext/trunc and remove this transform.
Jakub Kuderski58ea4ee2015-09-10 11:31:20 +0000782 // Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type
783 // conversion.
784 // It works because bits coming from sign extension have the same value as
Sanjay Patel1de794a2015-11-17 18:46:56 +0000785 // the sign bit of the original value; performing ashr instead of lshr
Jakub Kuderski58ea4ee2015-09-10 11:31:20 +0000786 // generates bits of the same value as the sign bit.
787 if (Src->hasOneUse() &&
Sanjay Patel6844e212017-05-09 16:24:59 +0000788 match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst)))) {
789 Value *SExt = cast<Instruction>(Src)->getOperand(0);
790 const unsigned SExtSize = SExt->getType()->getPrimitiveSizeInBits();
Jakub Kuderski58ea4ee2015-09-10 11:31:20 +0000791 const unsigned ASize = A->getType()->getPrimitiveSizeInBits();
Davide Italiano21a49dc2017-05-21 20:30:27 +0000792 const unsigned CISize = CI.getType()->getPrimitiveSizeInBits();
793 const unsigned MaxAmt = SExtSize - std::max(CISize, ASize);
Sanjay Patel6844e212017-05-09 16:24:59 +0000794 unsigned ShiftAmt = Cst->getZExtValue();
Davide Italiano21a49dc2017-05-21 20:30:27 +0000795
Jakub Kuderski58ea4ee2015-09-10 11:31:20 +0000796 // This optimization can be only performed when zero bits generated by
797 // the original lshr aren't pulled into the value after truncation, so we
Sanjay Patel6844e212017-05-09 16:24:59 +0000798 // can only shift by values no larger than the number of extension bits.
799 // FIXME: Instead of bailing when the shift is too large, use and to clear
800 // the extra bits.
Davide Italiano21a49dc2017-05-21 20:30:27 +0000801 if (ShiftAmt <= MaxAmt) {
802 if (CISize == ASize)
803 return BinaryOperator::CreateAShr(A, ConstantInt::get(CI.getType(),
804 std::min(ShiftAmt, ASize - 1)));
805 if (SExt->hasOneUse()) {
Craig Topperbb4069e2017-07-07 23:16:26 +0000806 Value *Shift = Builder.CreateAShr(A, std::min(ShiftAmt, ASize - 1));
Davide Italiano21a49dc2017-05-21 20:30:27 +0000807 Shift->takeName(Src);
808 return CastInst::CreateIntegerCast(Shift, CI.getType(), true);
809 }
Jakub Kuderski58ea4ee2015-09-10 11:31:20 +0000810 }
811 }
812
Sanjay Patel94da1de2017-08-05 15:19:18 +0000813 if (Instruction *I = narrowBinOp(CI))
Sanjay Patelaa8b28e2016-11-30 20:48:54 +0000814 return I;
815
Craig Topperbb4069e2017-07-07 23:16:26 +0000816 if (Instruction *I = shrinkSplatShuffle(CI, Builder))
Sanjay Patel53fa17a2017-03-07 21:45:16 +0000817 return I;
818
Craig Topperbb4069e2017-07-07 23:16:26 +0000819 if (Instruction *I = shrinkInsertElt(CI, Builder))
Sanjay Patelfe970512017-03-07 23:27:14 +0000820 return I;
821
Sanjay Patelf09d1bf2015-11-17 18:37:23 +0000822 if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
Sanjay Patel2217f752017-01-31 17:25:42 +0000823 shouldChangeType(SrcTy, DestTy)) {
Matt Arsenaulte2e6cfe2016-09-13 19:43:57 +0000824 // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
825 // dest type is native and cst < dest size.
826 if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst))) &&
827 !match(A, m_Shr(m_Value(), m_Constant()))) {
828 // Skip shifts of shift by constants. It undoes a combine in
829 // FoldShiftByConstant and is the extend in reg pattern.
830 const unsigned DestSize = DestTy->getScalarSizeInBits();
831 if (Cst->getValue().ult(DestSize)) {
Craig Topperbb4069e2017-07-07 23:16:26 +0000832 Value *NewTrunc = Builder.CreateTrunc(A, DestTy, A->getName() + ".tr");
Matt Arsenaulte2e6cfe2016-09-13 19:43:57 +0000833
834 return BinaryOperator::Create(
835 Instruction::Shl, NewTrunc,
836 ConstantInt::get(DestTy, Cst->getValue().trunc(DestSize)));
837 }
838 }
Chris Lattner9c10d582011-01-15 06:32:33 +0000839 }
Chris Lattner2b295a02010-01-04 07:53:58 +0000840
Craig Toppercb220392017-07-06 23:18:43 +0000841 if (Instruction *I = foldVecTruncToExtElt(CI, *this))
Sanjay Patelf727e382015-12-14 16:16:54 +0000842 return I;
843
Craig Topperf40110f2014-04-25 05:29:35 +0000844 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +0000845}
846
Tobias Grosser8ef834c2016-07-19 09:06:08 +0000847Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, ZExtInst &CI,
848 bool DoTransform) {
Chris Lattner2b295a02010-01-04 07:53:58 +0000849 // If we are just checking for a icmp eq of a single bit and zext'ing it
850 // to an integer, then shift the bit to the appropriate place and then
851 // cast to integer to avoid the comparison.
Craig Topper4431bfe2017-08-29 18:58:13 +0000852 const APInt *Op1CV;
853 if (match(ICI->getOperand(1), m_APInt(Op1CV))) {
Craig Topper3529aa52013-01-24 05:22:40 +0000854
Chris Lattner2b295a02010-01-04 07:53:58 +0000855 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
856 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
Craig Topper4431bfe2017-08-29 18:58:13 +0000857 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isNullValue()) ||
858 (ICI->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnesValue())) {
Tobias Grosser8ef834c2016-07-19 09:06:08 +0000859 if (!DoTransform) return ICI;
Chris Lattner2b295a02010-01-04 07:53:58 +0000860
861 Value *In = ICI->getOperand(0);
862 Value *Sh = ConstantInt::get(In->getType(),
Sanjay Patel16395dd2015-12-30 18:31:30 +0000863 In->getType()->getScalarSizeInBits() - 1);
Craig Topperbb4069e2017-07-07 23:16:26 +0000864 In = Builder.CreateLShr(In, Sh, In->getName() + ".lobit");
Chris Lattner2b295a02010-01-04 07:53:58 +0000865 if (In->getType() != CI.getType())
Craig Topperbb4069e2017-07-07 23:16:26 +0000866 In = Builder.CreateIntCast(In, CI.getType(), false /*ZExt*/);
Chris Lattner2b295a02010-01-04 07:53:58 +0000867
868 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
869 Constant *One = ConstantInt::get(In->getType(), 1);
Craig Topperbb4069e2017-07-07 23:16:26 +0000870 In = Builder.CreateXor(In, One, In->getName() + ".not");
Chris Lattner2b295a02010-01-04 07:53:58 +0000871 }
872
Sanjay Patel4b198802016-02-01 22:23:39 +0000873 return replaceInstUsesWith(CI, In);
Chris Lattner2b295a02010-01-04 07:53:58 +0000874 }
Chad Rosier385d9f62011-11-30 01:59:59 +0000875
Sylvestre Ledru91ce36c2012-09-27 10:14:43 +0000876 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
877 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
878 // zext (X == 1) to i32 --> X iff X has only the low bit set.
879 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
880 // zext (X != 0) to i32 --> X iff X has only the low bit set.
881 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
882 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
883 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
Craig Topper4431bfe2017-08-29 18:58:13 +0000884 if ((Op1CV->isNullValue() || Op1CV->isPowerOf2()) &&
Chris Lattner2b295a02010-01-04 07:53:58 +0000885 // This only works for EQ and NE
886 ICI->isEquality()) {
887 // If Op1C some other power of two, convert:
Craig Topper8205a1a2017-05-24 16:53:07 +0000888 KnownBits Known = computeKnownBits(ICI->getOperand(0), 0, &CI);
Craig Topper3529aa52013-01-24 05:22:40 +0000889
Craig Topperb45eabc2017-04-26 16:39:58 +0000890 APInt KnownZeroMask(~Known.Zero);
Chris Lattner2b295a02010-01-04 07:53:58 +0000891 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
Tobias Grosser8ef834c2016-07-19 09:06:08 +0000892 if (!DoTransform) return ICI;
Chris Lattner2b295a02010-01-04 07:53:58 +0000893
894 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
Craig Topper4431bfe2017-08-29 18:58:13 +0000895 if (!Op1CV->isNullValue() && (*Op1CV != KnownZeroMask)) {
Chris Lattner2b295a02010-01-04 07:53:58 +0000896 // (X&4) == 2 --> false
897 // (X&4) != 2 --> true
Craig Topper17b0c782017-10-05 07:59:11 +0000898 Constant *Res = ConstantInt::get(CI.getType(), isNE);
Sanjay Patel4b198802016-02-01 22:23:39 +0000899 return replaceInstUsesWith(CI, Res);
Chris Lattner2b295a02010-01-04 07:53:58 +0000900 }
Craig Topper3529aa52013-01-24 05:22:40 +0000901
Sanjay Patel16395dd2015-12-30 18:31:30 +0000902 uint32_t ShAmt = KnownZeroMask.logBase2();
Chris Lattner2b295a02010-01-04 07:53:58 +0000903 Value *In = ICI->getOperand(0);
Sanjay Patel16395dd2015-12-30 18:31:30 +0000904 if (ShAmt) {
Chris Lattner2b295a02010-01-04 07:53:58 +0000905 // Perform a logical shr by shiftamt.
906 // Insert the shift to put the result in the low bit.
Craig Topperbb4069e2017-07-07 23:16:26 +0000907 In = Builder.CreateLShr(In, ConstantInt::get(In->getType(), ShAmt),
908 In->getName() + ".lobit");
Chris Lattner2b295a02010-01-04 07:53:58 +0000909 }
Craig Topper3529aa52013-01-24 05:22:40 +0000910
Craig Topper4431bfe2017-08-29 18:58:13 +0000911 if (!Op1CV->isNullValue() == isNE) { // Toggle the low bit.
Chris Lattner2b295a02010-01-04 07:53:58 +0000912 Constant *One = ConstantInt::get(In->getType(), 1);
Craig Topperbb4069e2017-07-07 23:16:26 +0000913 In = Builder.CreateXor(In, One);
Chris Lattner2b295a02010-01-04 07:53:58 +0000914 }
Craig Topper3529aa52013-01-24 05:22:40 +0000915
Chris Lattner2b295a02010-01-04 07:53:58 +0000916 if (CI.getType() == In->getType())
Sanjay Patel4b198802016-02-01 22:23:39 +0000917 return replaceInstUsesWith(CI, In);
Tobias Grosser8757e382016-08-03 19:30:35 +0000918
Craig Topperbb4069e2017-07-07 23:16:26 +0000919 Value *IntCast = Builder.CreateIntCast(In, CI.getType(), false);
Tobias Grosser8757e382016-08-03 19:30:35 +0000920 return replaceInstUsesWith(CI, IntCast);
Chris Lattner2b295a02010-01-04 07:53:58 +0000921 }
922 }
923 }
924
925 // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
926 // It is also profitable to transform icmp eq into not(xor(A, B)) because that
927 // may lead to additional simplifications.
928 if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
Chris Lattner229907c2011-07-18 04:54:35 +0000929 if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
Chris Lattner2b295a02010-01-04 07:53:58 +0000930 Value *LHS = ICI->getOperand(0);
931 Value *RHS = ICI->getOperand(1);
932
Craig Topper8205a1a2017-05-24 16:53:07 +0000933 KnownBits KnownLHS = computeKnownBits(LHS, 0, &CI);
934 KnownBits KnownRHS = computeKnownBits(RHS, 0, &CI);
Chris Lattner2b295a02010-01-04 07:53:58 +0000935
Craig Topperb45eabc2017-04-26 16:39:58 +0000936 if (KnownLHS.Zero == KnownRHS.Zero && KnownLHS.One == KnownRHS.One) {
937 APInt KnownBits = KnownLHS.Zero | KnownLHS.One;
Chris Lattner2b295a02010-01-04 07:53:58 +0000938 APInt UnknownBit = ~KnownBits;
939 if (UnknownBit.countPopulation() == 1) {
Tobias Grosser8ef834c2016-07-19 09:06:08 +0000940 if (!DoTransform) return ICI;
Chris Lattner2b295a02010-01-04 07:53:58 +0000941
Craig Topperbb4069e2017-07-07 23:16:26 +0000942 Value *Result = Builder.CreateXor(LHS, RHS);
Chris Lattner2b295a02010-01-04 07:53:58 +0000943
944 // Mask off any bits that are set and won't be shifted away.
Craig Topperb45eabc2017-04-26 16:39:58 +0000945 if (KnownLHS.One.uge(UnknownBit))
Craig Topperbb4069e2017-07-07 23:16:26 +0000946 Result = Builder.CreateAnd(Result,
Chris Lattner2b295a02010-01-04 07:53:58 +0000947 ConstantInt::get(ITy, UnknownBit));
948
949 // Shift the bit we're testing down to the lsb.
Craig Topperbb4069e2017-07-07 23:16:26 +0000950 Result = Builder.CreateLShr(
Chris Lattner2b295a02010-01-04 07:53:58 +0000951 Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
952
953 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
Craig Topperbb4069e2017-07-07 23:16:26 +0000954 Result = Builder.CreateXor(Result, ConstantInt::get(ITy, 1));
Chris Lattner2b295a02010-01-04 07:53:58 +0000955 Result->takeName(ICI);
Sanjay Patel4b198802016-02-01 22:23:39 +0000956 return replaceInstUsesWith(CI, Result);
Chris Lattner2b295a02010-01-04 07:53:58 +0000957 }
958 }
959 }
960 }
961
Craig Topperf40110f2014-04-25 05:29:35 +0000962 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +0000963}
964
Sanjay Patel2fbab9d82015-09-09 14:34:26 +0000965/// Determine if the specified value can be computed in the specified wider type
966/// and produce the same low bits. If not, return false.
Chris Lattner172630a2010-01-11 02:43:35 +0000967///
Chris Lattner12bd8992010-01-11 03:32:00 +0000968/// If this function returns true, it can also return a non-zero number of bits
969/// (in BitsToClear) which indicates that the value it computes is correct for
970/// the zero extend, but that the additional BitsToClear bits need to be zero'd
971/// out. For example, to promote something like:
972///
973/// %B = trunc i64 %A to i32
974/// %C = lshr i32 %B, 8
975/// %E = zext i32 %C to i64
976///
977/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
978/// set to 8 to indicate that the promoted value needs to have bits 24-31
979/// cleared in addition to bits 32-63. Since an 'and' will be generated to
980/// clear the top bits anyway, doing this has no extra cost.
981///
Chris Lattner172630a2010-01-11 02:43:35 +0000982/// This function works on both vectors and scalars.
Sanjay Patele2834412015-09-09 14:54:29 +0000983static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear,
Hal Finkel60db0582014-09-07 18:57:58 +0000984 InstCombiner &IC, Instruction *CxtI) {
Chris Lattner12bd8992010-01-11 03:32:00 +0000985 BitsToClear = 0;
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000986 if (canAlwaysEvaluateInType(V, Ty))
Chris Lattnerb7be7cc2010-01-10 02:50:04 +0000987 return true;
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000988 if (canNotEvaluateInType(V, Ty))
989 return false;
Craig Topper3529aa52013-01-24 05:22:40 +0000990
Sanjay Patel1b66dee2018-01-31 14:55:53 +0000991 auto *I = cast<Instruction>(V);
992 unsigned Tmp;
993 switch (I->getOpcode()) {
Chris Lattner39d2daa2010-01-10 20:25:54 +0000994 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
995 case Instruction::SExt: // zext(sext(x)) -> sext(x).
996 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
997 return true;
Chris Lattnerc3aca382010-01-10 00:58:42 +0000998 case Instruction::And:
Chris Lattnerc3aca382010-01-10 00:58:42 +0000999 case Instruction::Or:
1000 case Instruction::Xor:
Chris Lattnerc3aca382010-01-10 00:58:42 +00001001 case Instruction::Add:
1002 case Instruction::Sub:
1003 case Instruction::Mul:
Sanjay Patele2834412015-09-09 14:54:29 +00001004 if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI) ||
1005 !canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI))
Chris Lattner12bd8992010-01-11 03:32:00 +00001006 return false;
1007 // These can all be promoted if neither operand has 'bits to clear'.
1008 if (BitsToClear == 0 && Tmp == 0)
1009 return true;
Craig Topper3529aa52013-01-24 05:22:40 +00001010
Chris Lattner0a854202010-01-11 04:05:13 +00001011 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
1012 // other side, BitsToClear is ok.
Sanjay Patel1e6ca442016-11-22 22:54:36 +00001013 if (Tmp == 0 && I->isBitwiseLogicOp()) {
Chris Lattner0a854202010-01-11 04:05:13 +00001014 // We use MaskedValueIsZero here for generality, but the case we care
1015 // about the most is constant RHS.
1016 unsigned VSize = V->getType()->getScalarSizeInBits();
Hal Finkel60db0582014-09-07 18:57:58 +00001017 if (IC.MaskedValueIsZero(I->getOperand(1),
1018 APInt::getHighBitsSet(VSize, BitsToClear),
Craig Toppercc255bc2017-08-21 16:04:11 +00001019 0, CxtI)) {
1020 // If this is an And instruction and all of the BitsToClear are
1021 // known to be zero we can reset BitsToClear.
Sanjay Patel1b66dee2018-01-31 14:55:53 +00001022 if (I->getOpcode() == Instruction::And)
Craig Toppercc255bc2017-08-21 16:04:11 +00001023 BitsToClear = 0;
Chris Lattner0a854202010-01-11 04:05:13 +00001024 return true;
Craig Toppercc255bc2017-08-21 16:04:11 +00001025 }
Chris Lattner0a854202010-01-11 04:05:13 +00001026 }
Craig Topper3529aa52013-01-24 05:22:40 +00001027
Chris Lattner0a854202010-01-11 04:05:13 +00001028 // Otherwise, we don't know how to analyze this BitsToClear case yet.
Chris Lattner12bd8992010-01-11 03:32:00 +00001029 return false;
Craig Topper3529aa52013-01-24 05:22:40 +00001030
Craig Topper0a1a2762017-08-15 22:48:41 +00001031 case Instruction::Shl: {
Benjamin Kramer14e915f2013-05-10 16:26:37 +00001032 // We can promote shl(x, cst) if we can promote x. Since shl overwrites the
1033 // upper bits we can reduce BitsToClear by the shift amount.
Craig Topper0a1a2762017-08-15 22:48:41 +00001034 const APInt *Amt;
1035 if (match(I->getOperand(1), m_APInt(Amt))) {
Sanjay Patele2834412015-09-09 14:54:29 +00001036 if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
Benjamin Kramer14e915f2013-05-10 16:26:37 +00001037 return false;
1038 uint64_t ShiftAmt = Amt->getZExtValue();
1039 BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0;
1040 return true;
1041 }
1042 return false;
Craig Topper0a1a2762017-08-15 22:48:41 +00001043 }
1044 case Instruction::LShr: {
Chris Lattner12bd8992010-01-11 03:32:00 +00001045 // We can promote lshr(x, cst) if we can promote x. This requires the
1046 // ultimate 'and' to clear out the high zero bits we're clearing out though.
Craig Topper0a1a2762017-08-15 22:48:41 +00001047 const APInt *Amt;
1048 if (match(I->getOperand(1), m_APInt(Amt))) {
Sanjay Patele2834412015-09-09 14:54:29 +00001049 if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI))
Chris Lattner12bd8992010-01-11 03:32:00 +00001050 return false;
1051 BitsToClear += Amt->getZExtValue();
1052 if (BitsToClear > V->getType()->getScalarSizeInBits())
1053 BitsToClear = V->getType()->getScalarSizeInBits();
1054 return true;
1055 }
1056 // Cannot promote variable LSHR.
1057 return false;
Craig Topper0a1a2762017-08-15 22:48:41 +00001058 }
Chris Lattnerc3aca382010-01-10 00:58:42 +00001059 case Instruction::Select:
Sanjay Patele2834412015-09-09 14:54:29 +00001060 if (!canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI) ||
1061 !canEvaluateZExtd(I->getOperand(2), Ty, BitsToClear, IC, CxtI) ||
Chris Lattner0a854202010-01-11 04:05:13 +00001062 // TODO: If important, we could handle the case when the BitsToClear are
1063 // known zero in the disagreeing side.
Chris Lattner12bd8992010-01-11 03:32:00 +00001064 Tmp != BitsToClear)
1065 return false;
1066 return true;
Craig Topper3529aa52013-01-24 05:22:40 +00001067
Chris Lattnerc3aca382010-01-10 00:58:42 +00001068 case Instruction::PHI: {
1069 // We can change a phi if we can change all operands. Note that we never
1070 // get into trouble with cyclic PHIs here because we only consider
1071 // instructions with a single use.
1072 PHINode *PN = cast<PHINode>(I);
Sanjay Patele2834412015-09-09 14:54:29 +00001073 if (!canEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear, IC, CxtI))
Chris Lattner12bd8992010-01-11 03:32:00 +00001074 return false;
Chris Lattnerb7be7cc2010-01-10 02:50:04 +00001075 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
Sanjay Patele2834412015-09-09 14:54:29 +00001076 if (!canEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp, IC, CxtI) ||
Chris Lattner0a854202010-01-11 04:05:13 +00001077 // TODO: If important, we could handle the case when the BitsToClear
1078 // are known zero in the disagreeing input.
Chris Lattner12bd8992010-01-11 03:32:00 +00001079 Tmp != BitsToClear)
1080 return false;
Chris Lattnerb7be7cc2010-01-10 02:50:04 +00001081 return true;
Chris Lattnerc3aca382010-01-10 00:58:42 +00001082 }
1083 default:
1084 // TODO: Can handle more cases here.
Chris Lattnerb7be7cc2010-01-10 02:50:04 +00001085 return false;
Chris Lattnerc3aca382010-01-10 00:58:42 +00001086 }
1087}
1088
Chris Lattner2b295a02010-01-04 07:53:58 +00001089Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
Nick Lewycky80ea0032013-01-14 20:56:10 +00001090 // If this zero extend is only used by a truncate, let the truncate be
Chris Lattner49d2c972010-01-10 02:39:31 +00001091 // eliminated before we try to optimize this zext.
Chandler Carruthcdf47882014-03-09 03:16:01 +00001092 if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
Craig Topperf40110f2014-04-25 05:29:35 +00001093 return nullptr;
Craig Topper3529aa52013-01-24 05:22:40 +00001094
Chris Lattner2b295a02010-01-04 07:53:58 +00001095 // If one of the common conversion will work, do it.
Chris Lattner883550a2010-01-10 01:00:46 +00001096 if (Instruction *Result = commonCastTransforms(CI))
Chris Lattner2b295a02010-01-04 07:53:58 +00001097 return Result;
1098
Chris Lattner883550a2010-01-10 01:00:46 +00001099 Value *Src = CI.getOperand(0);
Chris Lattner229907c2011-07-18 04:54:35 +00001100 Type *SrcTy = Src->getType(), *DestTy = CI.getType();
Craig Topper3529aa52013-01-24 05:22:40 +00001101
Sanjay Patel1a6e9ec2018-12-17 20:27:43 +00001102 // Try to extend the entire expression tree to the wide destination type.
Chris Lattner12bd8992010-01-11 03:32:00 +00001103 unsigned BitsToClear;
Sanjay Patel1a6e9ec2018-12-17 20:27:43 +00001104 if (shouldChangeType(SrcTy, DestTy) &&
Sanjay Patele2834412015-09-09 14:54:29 +00001105 canEvaluateZExtd(Src, DestTy, BitsToClear, *this, &CI)) {
Bjorn Petterssonc98dabb2017-03-16 13:22:01 +00001106 assert(BitsToClear <= SrcTy->getScalarSizeInBits() &&
1107 "Can't clear more bits than in SrcTy");
Craig Topper3529aa52013-01-24 05:22:40 +00001108
Chris Lattner49d2c972010-01-10 02:39:31 +00001109 // Okay, we can transform this! Insert the new expression now.
Nicola Zaghend34e60c2018-05-14 12:53:11 +00001110 LLVM_DEBUG(
1111 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1112 " to avoid zero extend: "
1113 << CI << '\n');
Chris Lattner49d2c972010-01-10 02:39:31 +00001114 Value *Res = EvaluateInDifferentType(Src, DestTy, false);
1115 assert(Res->getType() == DestTy);
Craig Topper3529aa52013-01-24 05:22:40 +00001116
Vedant Kumar6379a622018-07-06 17:32:39 +00001117 // Preserve debug values referring to Src if the zext is its last use.
1118 if (auto *SrcOp = dyn_cast<Instruction>(Src))
1119 if (SrcOp->hasOneUse())
1120 replaceAllDbgUsesWith(*SrcOp, *Res, CI, DT);
Anastasis Grammenos509d7972018-07-04 09:55:46 +00001121
Chris Lattner12bd8992010-01-11 03:32:00 +00001122 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
1123 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
Craig Topper3529aa52013-01-24 05:22:40 +00001124
Chris Lattner49d2c972010-01-10 02:39:31 +00001125 // If the high bits are already filled with zeros, just replace this
1126 // cast with the result.
Hal Finkel60db0582014-09-07 18:57:58 +00001127 if (MaskedValueIsZero(Res,
1128 APInt::getHighBitsSet(DestBitSize,
1129 DestBitSize-SrcBitsKept),
1130 0, &CI))
Sanjay Patel4b198802016-02-01 22:23:39 +00001131 return replaceInstUsesWith(CI, Res);
Craig Topper3529aa52013-01-24 05:22:40 +00001132
Chris Lattner49d2c972010-01-10 02:39:31 +00001133 // We need to emit an AND to clear the high bits.
Chris Lattner39d2daa2010-01-10 20:25:54 +00001134 Constant *C = ConstantInt::get(Res->getType(),
Chris Lattner12bd8992010-01-11 03:32:00 +00001135 APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
Chris Lattner49d2c972010-01-10 02:39:31 +00001136 return BinaryOperator::CreateAnd(Res, C);
Chris Lattnerc3aca382010-01-10 00:58:42 +00001137 }
Chris Lattner2b295a02010-01-04 07:53:58 +00001138
1139 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
1140 // types and if the sizes are just right we can convert this into a logical
1141 // 'and' which will be much cheaper than the pair of casts.
1142 if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
Chris Lattnerd8509422010-01-10 07:08:30 +00001143 // TODO: Subsume this into EvaluateInDifferentType.
Craig Topper3529aa52013-01-24 05:22:40 +00001144
Chris Lattner2b295a02010-01-04 07:53:58 +00001145 // Get the sizes of the types involved. We know that the intermediate type
1146 // will be smaller than A or C, but don't know the relation between A and C.
1147 Value *A = CSrc->getOperand(0);
1148 unsigned SrcSize = A->getType()->getScalarSizeInBits();
1149 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
1150 unsigned DstSize = CI.getType()->getScalarSizeInBits();
1151 // If we're actually extending zero bits, then if
1152 // SrcSize < DstSize: zext(a & mask)
1153 // SrcSize == DstSize: a & mask
1154 // SrcSize > DstSize: trunc(a) & mask
1155 if (SrcSize < DstSize) {
1156 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1157 Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
Craig Topperbb4069e2017-07-07 23:16:26 +00001158 Value *And = Builder.CreateAnd(A, AndConst, CSrc->getName() + ".mask");
Chris Lattner2b295a02010-01-04 07:53:58 +00001159 return new ZExtInst(And, CI.getType());
1160 }
Craig Topper3529aa52013-01-24 05:22:40 +00001161
Chris Lattner2b295a02010-01-04 07:53:58 +00001162 if (SrcSize == DstSize) {
1163 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
1164 return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
1165 AndValue));
1166 }
1167 if (SrcSize > DstSize) {
Craig Topperbb4069e2017-07-07 23:16:26 +00001168 Value *Trunc = Builder.CreateTrunc(A, CI.getType());
Chris Lattner2b295a02010-01-04 07:53:58 +00001169 APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
Craig Topper3529aa52013-01-24 05:22:40 +00001170 return BinaryOperator::CreateAnd(Trunc,
Chris Lattner2b295a02010-01-04 07:53:58 +00001171 ConstantInt::get(Trunc->getType(),
Chris Lattnerd8509422010-01-10 07:08:30 +00001172 AndValue));
Chris Lattner2b295a02010-01-04 07:53:58 +00001173 }
1174 }
1175
1176 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1177 return transformZExtICmp(ICI, CI);
1178
1179 BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
1180 if (SrcI && SrcI->getOpcode() == Instruction::Or) {
Tobias Grosser8757e382016-08-03 19:30:35 +00001181 // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) if at least one
1182 // of the (zext icmp) can be eliminated. If so, immediately perform the
1183 // according elimination.
Chris Lattner2b295a02010-01-04 07:53:58 +00001184 ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
1185 ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
1186 if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
1187 (transformZExtICmp(LHS, CI, false) ||
1188 transformZExtICmp(RHS, CI, false))) {
Tobias Grosser8757e382016-08-03 19:30:35 +00001189 // zext (or icmp, icmp) -> or (zext icmp), (zext icmp)
Craig Topperbb4069e2017-07-07 23:16:26 +00001190 Value *LCast = Builder.CreateZExt(LHS, CI.getType(), LHS->getName());
1191 Value *RCast = Builder.CreateZExt(RHS, CI.getType(), RHS->getName());
Tobias Grosser8757e382016-08-03 19:30:35 +00001192 BinaryOperator *Or = BinaryOperator::Create(Instruction::Or, LCast, RCast);
1193
1194 // Perform the elimination.
1195 if (auto *LZExt = dyn_cast<ZExtInst>(LCast))
1196 transformZExtICmp(LHS, *LZExt);
1197 if (auto *RZExt = dyn_cast<ZExtInst>(RCast))
1198 transformZExtICmp(RHS, *RZExt);
1199
1200 return Or;
Chris Lattner2b295a02010-01-04 07:53:58 +00001201 }
1202 }
1203
Benjamin Kramerb80e1692014-01-19 20:05:13 +00001204 // zext(trunc(X) & C) -> (X & zext(C)).
1205 Constant *C;
1206 Value *X;
1207 if (SrcI &&
1208 match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
1209 X->getType() == CI.getType())
1210 return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType()));
Chris Lattner2b295a02010-01-04 07:53:58 +00001211
Benjamin Kramerb80e1692014-01-19 20:05:13 +00001212 // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
1213 Value *And;
1214 if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
1215 match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
1216 X->getType() == CI.getType()) {
1217 Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
Craig Topperbb4069e2017-07-07 23:16:26 +00001218 return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
Benjamin Kramerb80e1692014-01-19 20:05:13 +00001219 }
Chris Lattner2b295a02010-01-04 07:53:58 +00001220
Craig Topperf40110f2014-04-25 05:29:35 +00001221 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +00001222}
1223
Sanjay Patel2fbab9d82015-09-09 14:34:26 +00001224/// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
Benjamin Kramer398b8c52011-04-01 20:09:03 +00001225Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) {
1226 Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
1227 ICmpInst::Predicate Pred = ICI->getPredicate();
1228
David Majnemerc8bdd232014-10-27 05:47:49 +00001229 // Don't bother if Op1 isn't of vector or integer type.
1230 if (!Op1->getType()->isIntOrIntVectorTy())
1231 return nullptr;
1232
Sanjay Patel32445372018-06-21 17:51:44 +00001233 if ((Pred == ICmpInst::ICMP_SLT && match(Op1, m_ZeroInt())) ||
1234 (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))) {
Benjamin Kramer8b94c292011-04-01 22:29:18 +00001235 // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative
1236 // (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive
Sanjay Patel32445372018-06-21 17:51:44 +00001237 Value *Sh = ConstantInt::get(Op0->getType(),
1238 Op0->getType()->getScalarSizeInBits() - 1);
1239 Value *In = Builder.CreateAShr(Op0, Sh, Op0->getName() + ".lobit");
1240 if (In->getType() != CI.getType())
1241 In = Builder.CreateIntCast(In, CI.getType(), true /*SExt*/);
Benjamin Kramer398b8c52011-04-01 20:09:03 +00001242
Sanjay Patel32445372018-06-21 17:51:44 +00001243 if (Pred == ICmpInst::ICMP_SGT)
1244 In = Builder.CreateNot(In, In->getName() + ".not");
1245 return replaceInstUsesWith(CI, In);
Benjamin Kramerb80e1692014-01-19 20:05:13 +00001246 }
Benjamin Kramerd1217652011-04-01 20:09:10 +00001247
Benjamin Kramerb80e1692014-01-19 20:05:13 +00001248 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
Benjamin Kramerd1217652011-04-01 20:09:10 +00001249 // If we know that only one bit of the LHS of the icmp can be set and we
1250 // have an equality comparison with zero or a power of 2, we can transform
1251 // the icmp and sext into bitwise/integer operations.
Benjamin Kramer5cad4532011-04-01 22:22:11 +00001252 if (ICI->hasOneUse() &&
1253 ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
Craig Topper8205a1a2017-05-24 16:53:07 +00001254 KnownBits Known = computeKnownBits(Op0, 0, &CI);
Benjamin Kramerd1217652011-04-01 20:09:10 +00001255
Craig Topperb45eabc2017-04-26 16:39:58 +00001256 APInt KnownZeroMask(~Known.Zero);
Benjamin Kramerac2d5652011-04-01 20:15:16 +00001257 if (KnownZeroMask.isPowerOf2()) {
Benjamin Kramerd1217652011-04-01 20:09:10 +00001258 Value *In = ICI->getOperand(0);
1259
Benjamin Kramer50a281a2011-04-02 18:50:58 +00001260 // If the icmp tests for a known zero bit we can constant fold it.
1261 if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
1262 Value *V = Pred == ICmpInst::ICMP_NE ?
1263 ConstantInt::getAllOnesValue(CI.getType()) :
1264 ConstantInt::getNullValue(CI.getType());
Sanjay Patel4b198802016-02-01 22:23:39 +00001265 return replaceInstUsesWith(CI, V);
Benjamin Kramer50a281a2011-04-02 18:50:58 +00001266 }
Benjamin Kramer5cad4532011-04-01 22:22:11 +00001267
Benjamin Kramerd1217652011-04-01 20:09:10 +00001268 if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
1269 // sext ((x & 2^n) == 0) -> (x >> n) - 1
1270 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
1271 unsigned ShiftAmt = KnownZeroMask.countTrailingZeros();
1272 // Perform a right shift to place the desired bit in the LSB.
1273 if (ShiftAmt)
Craig Topperbb4069e2017-07-07 23:16:26 +00001274 In = Builder.CreateLShr(In,
1275 ConstantInt::get(In->getType(), ShiftAmt));
Benjamin Kramerd1217652011-04-01 20:09:10 +00001276
1277 // At this point "In" is either 1 or 0. Subtract 1 to turn
1278 // {1, 0} -> {0, -1}.
Craig Topperbb4069e2017-07-07 23:16:26 +00001279 In = Builder.CreateAdd(In,
1280 ConstantInt::getAllOnesValue(In->getType()),
1281 "sext");
Benjamin Kramerd1217652011-04-01 20:09:10 +00001282 } else {
1283 // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
Benjamin Kramer5cad4532011-04-01 22:22:11 +00001284 // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
Benjamin Kramerd1217652011-04-01 20:09:10 +00001285 unsigned ShiftAmt = KnownZeroMask.countLeadingZeros();
1286 // Perform a left shift to place the desired bit in the MSB.
1287 if (ShiftAmt)
Craig Topperbb4069e2017-07-07 23:16:26 +00001288 In = Builder.CreateShl(In,
1289 ConstantInt::get(In->getType(), ShiftAmt));
Benjamin Kramerd1217652011-04-01 20:09:10 +00001290
1291 // Distribute the bit over the whole bit width.
Craig Topperbb4069e2017-07-07 23:16:26 +00001292 In = Builder.CreateAShr(In, ConstantInt::get(In->getType(),
1293 KnownZeroMask.getBitWidth() - 1), "sext");
Benjamin Kramerd1217652011-04-01 20:09:10 +00001294 }
1295
1296 if (CI.getType() == In->getType())
Sanjay Patel4b198802016-02-01 22:23:39 +00001297 return replaceInstUsesWith(CI, In);
Benjamin Kramerd1217652011-04-01 20:09:10 +00001298 return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/);
1299 }
1300 }
Benjamin Kramer398b8c52011-04-01 20:09:03 +00001301 }
1302
Craig Topperf40110f2014-04-25 05:29:35 +00001303 return nullptr;
Benjamin Kramer398b8c52011-04-01 20:09:03 +00001304}
1305
Sanjay Patel2fbab9d82015-09-09 14:34:26 +00001306/// Return true if we can take the specified value and return it as type Ty
1307/// without inserting any new casts and without changing the value of the common
1308/// low bits. This is used by code that tries to promote integer operations to
1309/// a wider types will allow us to eliminate the extension.
Chris Lattnerc3aca382010-01-10 00:58:42 +00001310///
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001311/// This function works on both vectors and scalars.
Chris Lattnerc3aca382010-01-10 00:58:42 +00001312///
Sanjay Patele2834412015-09-09 14:54:29 +00001313static bool canEvaluateSExtd(Value *V, Type *Ty) {
Chris Lattnerc3aca382010-01-10 00:58:42 +00001314 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
1315 "Can't sign extend type to a smaller type");
Sanjay Patel1b66dee2018-01-31 14:55:53 +00001316 if (canAlwaysEvaluateInType(V, Ty))
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001317 return true;
Sanjay Patel1b66dee2018-01-31 14:55:53 +00001318 if (canNotEvaluateInType(V, Ty))
1319 return false;
Craig Topper3529aa52013-01-24 05:22:40 +00001320
Sanjay Patel1b66dee2018-01-31 14:55:53 +00001321 auto *I = cast<Instruction>(V);
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001322 switch (I->getOpcode()) {
Chris Lattner7dd540e2010-01-10 20:30:41 +00001323 case Instruction::SExt: // sext(sext(x)) -> sext(x)
1324 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1325 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1326 return true;
Chris Lattnerc3aca382010-01-10 00:58:42 +00001327 case Instruction::And:
1328 case Instruction::Or:
1329 case Instruction::Xor:
Chris Lattnerc3aca382010-01-10 00:58:42 +00001330 case Instruction::Add:
1331 case Instruction::Sub:
Chris Lattnerc3aca382010-01-10 00:58:42 +00001332 case Instruction::Mul:
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001333 // These operators can all arbitrarily be extended if their inputs can.
Sanjay Patele2834412015-09-09 14:54:29 +00001334 return canEvaluateSExtd(I->getOperand(0), Ty) &&
1335 canEvaluateSExtd(I->getOperand(1), Ty);
Craig Topper3529aa52013-01-24 05:22:40 +00001336
Chris Lattnerc3aca382010-01-10 00:58:42 +00001337 //case Instruction::Shl: TODO
1338 //case Instruction::LShr: TODO
Craig Topper3529aa52013-01-24 05:22:40 +00001339
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001340 case Instruction::Select:
Sanjay Patele2834412015-09-09 14:54:29 +00001341 return canEvaluateSExtd(I->getOperand(1), Ty) &&
1342 canEvaluateSExtd(I->getOperand(2), Ty);
Craig Topper3529aa52013-01-24 05:22:40 +00001343
Chris Lattnerc3aca382010-01-10 00:58:42 +00001344 case Instruction::PHI: {
1345 // We can change a phi if we can change all operands. Note that we never
1346 // get into trouble with cyclic PHIs here because we only consider
1347 // instructions with a single use.
1348 PHINode *PN = cast<PHINode>(I);
Pete Cooper833f34d2015-05-12 20:05:31 +00001349 for (Value *IncValue : PN->incoming_values())
Sanjay Patele2834412015-09-09 14:54:29 +00001350 if (!canEvaluateSExtd(IncValue, Ty)) return false;
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001351 return true;
Chris Lattnerc3aca382010-01-10 00:58:42 +00001352 }
1353 default:
1354 // TODO: Can handle more cases here.
1355 break;
1356 }
Craig Topper3529aa52013-01-24 05:22:40 +00001357
Chris Lattner1a05fdd2010-01-10 07:57:20 +00001358 return false;
Chris Lattnerc3aca382010-01-10 00:58:42 +00001359}
1360
Chris Lattner2b295a02010-01-04 07:53:58 +00001361Instruction *InstCombiner::visitSExt(SExtInst &CI) {
Arnaud A. de Grandmaison2e4df4f2013-02-13 00:19:19 +00001362 // If this sign extend is only used by a truncate, let the truncate be
1363 // eliminated before we try to optimize this sext.
Chandler Carruthcdf47882014-03-09 03:16:01 +00001364 if (CI.hasOneUse() && isa<TruncInst>(CI.user_back()))
Craig Topperf40110f2014-04-25 05:29:35 +00001365 return nullptr;
Craig Topper3529aa52013-01-24 05:22:40 +00001366
Chris Lattner883550a2010-01-10 01:00:46 +00001367 if (Instruction *I = commonCastTransforms(CI))
Chris Lattner2b295a02010-01-04 07:53:58 +00001368 return I;
Craig Topper3529aa52013-01-24 05:22:40 +00001369
Chris Lattner2b295a02010-01-04 07:53:58 +00001370 Value *Src = CI.getOperand(0);
Chris Lattner229907c2011-07-18 04:54:35 +00001371 Type *SrcTy = Src->getType(), *DestTy = CI.getType();
Chris Lattnerc3aca382010-01-10 00:58:42 +00001372
Philip Reames9ae15202015-02-14 00:05:36 +00001373 // If we know that the value being extended is positive, we can use a zext
Justin Bognerc7e4fbe2016-08-05 01:09:48 +00001374 // instead.
Craig Topper1a36b7d2017-05-15 06:39:41 +00001375 KnownBits Known = computeKnownBits(Src, 0, &CI);
1376 if (Known.isNonNegative()) {
Craig Topperbb4069e2017-07-07 23:16:26 +00001377 Value *ZExt = Builder.CreateZExt(Src, DestTy);
Sanjay Patel4b198802016-02-01 22:23:39 +00001378 return replaceInstUsesWith(CI, ZExt);
Philip Reames9ae15202015-02-14 00:05:36 +00001379 }
1380
Sanjay Patel1a6e9ec2018-12-17 20:27:43 +00001381 // Try to extend the entire expression tree to the wide destination type.
1382 if (shouldChangeType(SrcTy, DestTy) && canEvaluateSExtd(Src, DestTy)) {
Chris Lattner2fff10c2010-01-10 07:40:50 +00001383 // Okay, we can transform this! Insert the new expression now.
Nicola Zaghend34e60c2018-05-14 12:53:11 +00001384 LLVM_DEBUG(
1385 dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1386 " to avoid sign extend: "
1387 << CI << '\n');
Chris Lattner2fff10c2010-01-10 07:40:50 +00001388 Value *Res = EvaluateInDifferentType(Src, DestTy, true);
1389 assert(Res->getType() == DestTy);
1390
Chris Lattnerc3aca382010-01-10 00:58:42 +00001391 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
1392 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
Chris Lattner2fff10c2010-01-10 07:40:50 +00001393
1394 // If the high bits are already filled with sign bit, just replace this
1395 // cast with the result.
Hal Finkel60db0582014-09-07 18:57:58 +00001396 if (ComputeNumSignBits(Res, 0, &CI) > DestBitSize - SrcBitSize)
Sanjay Patel4b198802016-02-01 22:23:39 +00001397 return replaceInstUsesWith(CI, Res);
Craig Topper3529aa52013-01-24 05:22:40 +00001398
Chris Lattner2fff10c2010-01-10 07:40:50 +00001399 // We need to emit a shl + ashr to do the sign extend.
1400 Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
Craig Topperbb4069e2017-07-07 23:16:26 +00001401 return BinaryOperator::CreateAShr(Builder.CreateShl(Res, ShAmt, "sext"),
Chris Lattner2fff10c2010-01-10 07:40:50 +00001402 ShAmt);
Chris Lattnerc3aca382010-01-10 00:58:42 +00001403 }
Chris Lattner2b295a02010-01-04 07:53:58 +00001404
Sanjay Pateladf2ab12017-02-23 16:26:03 +00001405 // If the input is a trunc from the destination type, then turn sext(trunc(x))
Chris Lattner43f2fa62010-01-18 22:19:16 +00001406 // into shifts.
Sanjay Pateladf2ab12017-02-23 16:26:03 +00001407 Value *X;
1408 if (match(Src, m_OneUse(m_Trunc(m_Value(X)))) && X->getType() == DestTy) {
1409 // sext(trunc(X)) --> ashr(shl(X, C), C)
1410 unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
1411 unsigned DestBitSize = DestTy->getScalarSizeInBits();
1412 Constant *ShAmt = ConstantInt::get(DestTy, DestBitSize - SrcBitSize);
Craig Topperbb4069e2017-07-07 23:16:26 +00001413 return BinaryOperator::CreateAShr(Builder.CreateShl(X, ShAmt), ShAmt);
Sanjay Pateladf2ab12017-02-23 16:26:03 +00001414 }
Nate Begeman7aa18bf2010-12-17 23:12:19 +00001415
Benjamin Kramer398b8c52011-04-01 20:09:03 +00001416 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1417 return transformSExtICmp(ICI, CI);
Bill Wendling5e360552010-12-17 23:27:41 +00001418
Chris Lattner2b295a02010-01-04 07:53:58 +00001419 // If the input is a shl/ashr pair of a same constant, then this is a sign
1420 // extension from a smaller value. If we could trust arbitrary bitwidth
1421 // integers, we could turn this into a truncate to the smaller bit and then
1422 // use a sext for the whole extension. Since we don't, look deeper and check
1423 // for a truncate. If the source and dest are the same type, eliminate the
1424 // trunc and extend and just do shifts. For example, turn:
1425 // %a = trunc i32 %i to i8
1426 // %b = shl i8 %a, 6
1427 // %c = ashr i8 %b, 6
1428 // %d = sext i8 %c to i32
1429 // into:
1430 // %a = shl i32 %i, 30
1431 // %d = ashr i32 %a, 30
Craig Topperf40110f2014-04-25 05:29:35 +00001432 Value *A = nullptr;
Chris Lattnerc95a7a22010-01-10 01:04:31 +00001433 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
Craig Topperf40110f2014-04-25 05:29:35 +00001434 ConstantInt *BA = nullptr, *CA = nullptr;
Chris Lattnerc95a7a22010-01-10 01:04:31 +00001435 if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
Chris Lattner2b295a02010-01-04 07:53:58 +00001436 m_ConstantInt(CA))) &&
Chris Lattnerc95a7a22010-01-10 01:04:31 +00001437 BA == CA && A->getType() == CI.getType()) {
1438 unsigned MidSize = Src->getType()->getScalarSizeInBits();
1439 unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
1440 unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
1441 Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
Craig Topperbb4069e2017-07-07 23:16:26 +00001442 A = Builder.CreateShl(A, ShAmtV, CI.getName());
Chris Lattnerc95a7a22010-01-10 01:04:31 +00001443 return BinaryOperator::CreateAShr(A, ShAmtV);
Chris Lattner2b295a02010-01-04 07:53:58 +00001444 }
Craig Topper3529aa52013-01-24 05:22:40 +00001445
Craig Topperf40110f2014-04-25 05:29:35 +00001446 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +00001447}
1448
1449
Sanjay Patel2fbab9d82015-09-09 14:34:26 +00001450/// Return a Constant* for the specified floating-point constant if it fits
Chris Lattner2b295a02010-01-04 07:53:58 +00001451/// in the specified FP type without changing its value.
Craig Topperc7461e12018-03-02 21:25:18 +00001452static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
Chris Lattner2b295a02010-01-04 07:53:58 +00001453 bool losesInfo;
1454 APFloat F = CFP->getValueAPF();
1455 (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
Craig Topperc7461e12018-03-02 21:25:18 +00001456 return !losesInfo;
Chris Lattner2b295a02010-01-04 07:53:58 +00001457}
1458
Craig Topperc7461e12018-03-02 21:25:18 +00001459static Type *shrinkFPConstant(ConstantFP *CFP) {
Craig Topperb95298b2018-02-28 20:14:34 +00001460 if (CFP->getType() == Type::getPPC_FP128Ty(CFP->getContext()))
1461 return nullptr; // No constant folding of this.
1462 // See if the value can be truncated to half and then reextended.
Craig Topperc7461e12018-03-02 21:25:18 +00001463 if (fitsInFPType(CFP, APFloat::IEEEhalf()))
1464 return Type::getHalfTy(CFP->getContext());
Craig Topperb95298b2018-02-28 20:14:34 +00001465 // See if the value can be truncated to float and then reextended.
Craig Topperc7461e12018-03-02 21:25:18 +00001466 if (fitsInFPType(CFP, APFloat::IEEEsingle()))
1467 return Type::getFloatTy(CFP->getContext());
Craig Topperb95298b2018-02-28 20:14:34 +00001468 if (CFP->getType()->isDoubleTy())
1469 return nullptr; // Won't shrink.
Craig Topperc7461e12018-03-02 21:25:18 +00001470 if (fitsInFPType(CFP, APFloat::IEEEdouble()))
1471 return Type::getDoubleTy(CFP->getContext());
Craig Topperb95298b2018-02-28 20:14:34 +00001472 // Don't try to shrink to various long double types.
1473 return nullptr;
1474}
1475
Craig Topper8452fac2018-03-05 18:04:12 +00001476// Determine if this is a vector of ConstantFPs and if so, return the minimal
1477// type we can safely truncate all elements to.
1478// TODO: Make these support undef elements.
1479static Type *shrinkFPConstantVector(Value *V) {
1480 auto *CV = dyn_cast<Constant>(V);
1481 if (!CV || !CV->getType()->isVectorTy())
1482 return nullptr;
1483
1484 Type *MinType = nullptr;
1485
1486 unsigned NumElts = CV->getType()->getVectorNumElements();
1487 for (unsigned i = 0; i != NumElts; ++i) {
1488 auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
1489 if (!CFP)
1490 return nullptr;
1491
1492 Type *T = shrinkFPConstant(CFP);
1493 if (!T)
1494 return nullptr;
1495
1496 // If we haven't found a type yet or this type has a larger mantissa than
1497 // our previous type, this is our new minimal type.
1498 if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth())
1499 MinType = T;
1500 }
1501
1502 // Make a vector type from the minimal type.
1503 return VectorType::get(MinType, NumElts);
1504}
1505
Craig Topperc7461e12018-03-02 21:25:18 +00001506/// Find the minimum FP type we can safely truncate to.
1507static Type *getMinimumFPType(Value *V) {
1508 if (auto *FPExt = dyn_cast<FPExtInst>(V))
1509 return FPExt->getOperand(0)->getType();
Craig Topper3529aa52013-01-24 05:22:40 +00001510
Chris Lattner2b295a02010-01-04 07:53:58 +00001511 // If this value is a constant, return the constant in the smallest FP type
1512 // that can accurately represent it. This allows us to turn
1513 // (float)((double)X+2.0) into x+2.0f.
Craig Topperb95298b2018-02-28 20:14:34 +00001514 if (auto *CFP = dyn_cast<ConstantFP>(V))
Craig Topperc7461e12018-03-02 21:25:18 +00001515 if (Type *T = shrinkFPConstant(CFP))
1516 return T;
Craig Topper3529aa52013-01-24 05:22:40 +00001517
Craig Topper8452fac2018-03-05 18:04:12 +00001518 // Try to shrink a vector of FP constants.
1519 if (Type *T = shrinkFPConstantVector(V))
1520 return T;
1521
Craig Topperc7461e12018-03-02 21:25:18 +00001522 return V->getType();
Chris Lattner2b295a02010-01-04 07:53:58 +00001523}
1524
Sanjay Patel286074e2018-03-24 15:41:59 +00001525Instruction *InstCombiner::visitFPTrunc(FPTruncInst &FPT) {
1526 if (Instruction *I = commonCastTransforms(FPT))
Chris Lattner2b295a02010-01-04 07:53:58 +00001527 return I;
Sanjay Patel286074e2018-03-24 15:41:59 +00001528
Stephen Canonc4549642013-11-28 21:38:05 +00001529 // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
Sanjay Patel5a7bdc92015-11-21 16:16:29 +00001530 // simplify this expression to avoid one or more of the trunc/extend
Stephen Canonc4549642013-11-28 21:38:05 +00001531 // operations if we can do so without changing the numerical results.
1532 //
1533 // The exact manner in which the widths of the operands interact to limit
1534 // what we can and cannot do safely varies from operation to operation, and
1535 // is explained below in the various case statements.
Sanjay Patel286074e2018-03-24 15:41:59 +00001536 Type *Ty = FPT.getType();
1537 BinaryOperator *OpI = dyn_cast<BinaryOperator>(FPT.getOperand(0));
Chris Lattner2b295a02010-01-04 07:53:58 +00001538 if (OpI && OpI->hasOneUse()) {
Craig Topperc7461e12018-03-02 21:25:18 +00001539 Type *LHSMinType = getMinimumFPType(OpI->getOperand(0));
1540 Type *RHSMinType = getMinimumFPType(OpI->getOperand(1));
Stephen Canonc4549642013-11-28 21:38:05 +00001541 unsigned OpWidth = OpI->getType()->getFPMantissaWidth();
Craig Topperc7461e12018-03-02 21:25:18 +00001542 unsigned LHSWidth = LHSMinType->getFPMantissaWidth();
1543 unsigned RHSWidth = RHSMinType->getFPMantissaWidth();
Stephen Canonc4549642013-11-28 21:38:05 +00001544 unsigned SrcWidth = std::max(LHSWidth, RHSWidth);
Sanjay Patel286074e2018-03-24 15:41:59 +00001545 unsigned DstWidth = Ty->getFPMantissaWidth();
Chris Lattner2b295a02010-01-04 07:53:58 +00001546 switch (OpI->getOpcode()) {
Stephen Canonc4549642013-11-28 21:38:05 +00001547 default: break;
1548 case Instruction::FAdd:
1549 case Instruction::FSub:
1550 // For addition and subtraction, the infinitely precise result can
1551 // essentially be arbitrarily wide; proving that double rounding
1552 // will not occur because the result of OpI is exact (as we will for
1553 // FMul, for example) is hopeless. However, we *can* nonetheless
1554 // frequently know that double rounding cannot occur (or that it is
Alp Tokercb402912014-01-24 17:20:08 +00001555 // innocuous) by taking advantage of the specific structure of
Stephen Canonc4549642013-11-28 21:38:05 +00001556 // infinitely-precise results that admit double rounding.
1557 //
Alp Tokercb402912014-01-24 17:20:08 +00001558 // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient
Stephen Canonc4549642013-11-28 21:38:05 +00001559 // to represent both sources, we can guarantee that the double
1560 // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis,
1561 // "A Rigorous Framework for Fully Supporting the IEEE Standard ..."
1562 // for proof of this fact).
1563 //
1564 // Note: Figueroa does not consider the case where DstFormat !=
1565 // SrcFormat. It's possible (likely even!) that this analysis
1566 // could be tightened for those cases, but they are rare (the main
1567 // case of interest here is (float)((double)float + float)).
1568 if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) {
Sanjay Patel286074e2018-03-24 15:41:59 +00001569 Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1570 Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
1571 Instruction *RI = BinaryOperator::Create(OpI->getOpcode(), LHS, RHS);
Owen Anderson48b842e2014-01-18 00:48:14 +00001572 RI->copyFastMathFlags(OpI);
1573 return RI;
Chris Lattner2b295a02010-01-04 07:53:58 +00001574 }
Stephen Canonc4549642013-11-28 21:38:05 +00001575 break;
1576 case Instruction::FMul:
1577 // For multiplication, the infinitely precise result has at most
1578 // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient
1579 // that such a value can be exactly represented, then no double
1580 // rounding can possibly occur; we can safely perform the operation
1581 // in the destination format if it can represent both sources.
1582 if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) {
Sanjay Patel286074e2018-03-24 15:41:59 +00001583 Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1584 Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
Sanjay Patel2a249582018-04-07 14:14:23 +00001585 return BinaryOperator::CreateFMulFMF(LHS, RHS, OpI);
Stephen Canonc4549642013-11-28 21:38:05 +00001586 }
1587 break;
1588 case Instruction::FDiv:
1589 // For division, we use again use the bound from Figueroa's
1590 // dissertation. I am entirely certain that this bound can be
1591 // tightened in the unbalanced operand case by an analysis based on
1592 // the diophantine rational approximation bound, but the well-known
1593 // condition used here is a good conservative first pass.
1594 // TODO: Tighten bound via rigorous analysis of the unbalanced case.
1595 if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) {
Sanjay Patel286074e2018-03-24 15:41:59 +00001596 Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty);
1597 Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty);
Sanjay Patel2a249582018-04-07 14:14:23 +00001598 return BinaryOperator::CreateFDivFMF(LHS, RHS, OpI);
Stephen Canonc4549642013-11-28 21:38:05 +00001599 }
1600 break;
Craig Topperc7461e12018-03-02 21:25:18 +00001601 case Instruction::FRem: {
Stephen Canonc4549642013-11-28 21:38:05 +00001602 // Remainder is straightforward. Remainder is always exact, so the
1603 // type of OpI doesn't enter into things at all. We simply evaluate
1604 // in whichever source type is larger, then convert to the
1605 // destination type.
Steven Wuf179d122014-12-12 18:48:37 +00001606 if (SrcWidth == OpWidth)
Steven Wu1f7402a2014-12-12 17:21:54 +00001607 break;
Craig Topperc7461e12018-03-02 21:25:18 +00001608 Value *LHS, *RHS;
1609 if (LHSWidth == SrcWidth) {
1610 LHS = Builder.CreateFPTrunc(OpI->getOperand(0), LHSMinType);
1611 RHS = Builder.CreateFPTrunc(OpI->getOperand(1), LHSMinType);
1612 } else {
1613 LHS = Builder.CreateFPTrunc(OpI->getOperand(0), RHSMinType);
1614 RHS = Builder.CreateFPTrunc(OpI->getOperand(1), RHSMinType);
Steven Wu1f7402a2014-12-12 17:21:54 +00001615 }
Craig Topperc7461e12018-03-02 21:25:18 +00001616
Sanjay Patel2a249582018-04-07 14:14:23 +00001617 Value *ExactResult = Builder.CreateFRemFMF(LHS, RHS, OpI);
Sanjay Patel286074e2018-03-24 15:41:59 +00001618 return CastInst::CreateFPCast(ExactResult, Ty);
Craig Topperc7461e12018-03-02 21:25:18 +00001619 }
Chris Lattner2b295a02010-01-04 07:53:58 +00001620 }
Owen Andersondbf0ca52013-01-10 22:06:52 +00001621
1622 // (fptrunc (fneg x)) -> (fneg (fptrunc x))
Cameron McInally384a74b2018-10-25 18:09:33 +00001623 Value *X;
1624 if (match(OpI, m_FNeg(m_Value(X)))) {
1625 Value *InnerTrunc = Builder.CreateFPTrunc(X, Ty);
Sanjay Patel2a249582018-04-07 14:14:23 +00001626 return BinaryOperator::CreateFNegFMF(InnerTrunc, OpI);
Owen Andersondbf0ca52013-01-10 22:06:52 +00001627 }
Chris Lattner2b295a02010-01-04 07:53:58 +00001628 }
Owen Andersondbf0ca52013-01-10 22:06:52 +00001629
Sanjay Patel286074e2018-03-24 15:41:59 +00001630 if (auto *II = dyn_cast<IntrinsicInst>(FPT.getOperand(0))) {
Owen Andersondbf0ca52013-01-10 22:06:52 +00001631 switch (II->getIntrinsicID()) {
Matt Arsenault72333442017-01-17 00:10:40 +00001632 default: break;
Matt Arsenault954a6242017-01-23 23:55:08 +00001633 case Intrinsic::ceil:
Sanjay Patel286074e2018-03-24 15:41:59 +00001634 case Intrinsic::fabs:
Matt Arsenault954a6242017-01-23 23:55:08 +00001635 case Intrinsic::floor:
Sanjay Patel286074e2018-03-24 15:41:59 +00001636 case Intrinsic::nearbyint:
Matt Arsenault954a6242017-01-23 23:55:08 +00001637 case Intrinsic::rint:
1638 case Intrinsic::round:
Matt Arsenault954a6242017-01-23 23:55:08 +00001639 case Intrinsic::trunc: {
Matt Arsenault6b00d402017-03-20 21:59:24 +00001640 Value *Src = II->getArgOperand(0);
1641 if (!Src->hasOneUse())
1642 break;
1643
1644 // Except for fabs, this transformation requires the input of the unary FP
1645 // operation to be itself an fpext from the type to which we're
1646 // truncating.
1647 if (II->getIntrinsicID() != Intrinsic::fabs) {
1648 FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Src);
Sanjay Patel286074e2018-03-24 15:41:59 +00001649 if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty)
Matt Arsenault6b00d402017-03-20 21:59:24 +00001650 break;
1651 }
1652
Matt Arsenault954a6242017-01-23 23:55:08 +00001653 // Do unary FP operation on smaller type.
Matt Arsenault72333442017-01-17 00:10:40 +00001654 // (fptrunc (fabs x)) -> (fabs (fptrunc x))
Sanjay Patel286074e2018-03-24 15:41:59 +00001655 Value *InnerTrunc = Builder.CreateFPTrunc(Src, Ty);
1656 Function *Overload = Intrinsic::getDeclaration(FPT.getModule(),
1657 II->getIntrinsicID(), Ty);
Matt Arsenault72333442017-01-17 00:10:40 +00001658 SmallVector<OperandBundleDef, 1> OpBundles;
1659 II->getOperandBundlesAsDefs(OpBundles);
Sanjay Patel286074e2018-03-24 15:41:59 +00001660 CallInst *NewCI = CallInst::Create(Overload, { InnerTrunc }, OpBundles,
1661 II->getName());
Matt Arsenault72333442017-01-17 00:10:40 +00001662 NewCI->copyFastMathFlags(II);
1663 return NewCI;
1664 }
Owen Andersondbf0ca52013-01-10 22:06:52 +00001665 }
1666 }
1667
Sanjay Patel286074e2018-03-24 15:41:59 +00001668 if (Instruction *I = shrinkInsertElt(FPT, Builder))
Sanjay Patelfe970512017-03-07 23:27:14 +00001669 return I;
1670
Craig Topperf40110f2014-04-25 05:29:35 +00001671 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +00001672}
1673
1674Instruction *InstCombiner::visitFPExt(CastInst &CI) {
1675 return commonCastTransforms(CI);
1676}
1677
Mehdi Aminib9a0fa42015-02-16 21:47:54 +00001678// fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
1679// This is safe if the intermediate type has enough bits in its mantissa to
1680// accurately represent all values of X. For example, this won't work with
1681// i64 -> float -> i64.
1682Instruction *InstCombiner::FoldItoFPtoI(Instruction &FI) {
1683 if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
1684 return nullptr;
1685 Instruction *OpI = cast<Instruction>(FI.getOperand(0));
1686
1687 Value *SrcI = OpI->getOperand(0);
1688 Type *FITy = FI.getType();
1689 Type *OpITy = OpI->getType();
1690 Type *SrcTy = SrcI->getType();
1691 bool IsInputSigned = isa<SIToFPInst>(OpI);
1692 bool IsOutputSigned = isa<FPToSIInst>(FI);
1693
1694 // We can safely assume the conversion won't overflow the output range,
1695 // because (for example) (uint8_t)18293.f is undefined behavior.
1696
1697 // Since we can assume the conversion won't overflow, our decision as to
1698 // whether the input will fit in the float should depend on the minimum
1699 // of the input range and output range.
1700
1701 // This means this is also safe for a signed input and unsigned output, since
1702 // a negative input would lead to undefined behavior.
1703 int InputSize = (int)SrcTy->getScalarSizeInBits() - IsInputSigned;
1704 int OutputSize = (int)FITy->getScalarSizeInBits() - IsOutputSigned;
1705 int ActualSize = std::min(InputSize, OutputSize);
1706
1707 if (ActualSize <= OpITy->getFPMantissaWidth()) {
1708 if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits()) {
1709 if (IsInputSigned && IsOutputSigned)
1710 return new SExtInst(SrcI, FITy);
1711 return new ZExtInst(SrcI, FITy);
1712 }
1713 if (FITy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits())
1714 return new TruncInst(SrcI, FITy);
1715 if (SrcTy == FITy)
Sanjay Patel4b198802016-02-01 22:23:39 +00001716 return replaceInstUsesWith(FI, SrcI);
Mehdi Aminib9a0fa42015-02-16 21:47:54 +00001717 return new BitCastInst(SrcI, FITy);
1718 }
1719 return nullptr;
1720}
1721
Chris Lattner2b295a02010-01-04 07:53:58 +00001722Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
1723 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
Craig Topperf40110f2014-04-25 05:29:35 +00001724 if (!OpI)
Chris Lattner2b295a02010-01-04 07:53:58 +00001725 return commonCastTransforms(FI);
1726
Mehdi Aminib9a0fa42015-02-16 21:47:54 +00001727 if (Instruction *I = FoldItoFPtoI(FI))
1728 return I;
Chris Lattner2b295a02010-01-04 07:53:58 +00001729
1730 return commonCastTransforms(FI);
1731}
1732
1733Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
1734 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
Craig Topperf40110f2014-04-25 05:29:35 +00001735 if (!OpI)
Chris Lattner2b295a02010-01-04 07:53:58 +00001736 return commonCastTransforms(FI);
Craig Topper3529aa52013-01-24 05:22:40 +00001737
Mehdi Aminib9a0fa42015-02-16 21:47:54 +00001738 if (Instruction *I = FoldItoFPtoI(FI))
1739 return I;
Craig Topper3529aa52013-01-24 05:22:40 +00001740
Chris Lattner2b295a02010-01-04 07:53:58 +00001741 return commonCastTransforms(FI);
1742}
1743
1744Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
1745 return commonCastTransforms(CI);
1746}
1747
1748Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
1749 return commonCastTransforms(CI);
1750}
1751
Chris Lattner2b295a02010-01-04 07:53:58 +00001752Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
Dan Gohman949458d2010-02-02 01:44:02 +00001753 // If the source integer type is not the intptr_t type for this target, do a
1754 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
1755 // cast to be exposed to other transforms.
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001756 unsigned AS = CI.getAddressSpace();
1757 if (CI.getOperand(0)->getType()->getScalarSizeInBits() !=
1758 DL.getPointerSizeInBits(AS)) {
1759 Type *Ty = DL.getIntPtrType(CI.getContext(), AS);
1760 if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
1761 Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements());
Benjamin Kramer944e0ab2013-02-05 20:22:40 +00001762
Craig Topperbb4069e2017-07-07 23:16:26 +00001763 Value *P = Builder.CreateZExtOrTrunc(CI.getOperand(0), Ty);
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001764 return new IntToPtrInst(P, CI.getType());
Chris Lattner2b295a02010-01-04 07:53:58 +00001765 }
Craig Topper3529aa52013-01-24 05:22:40 +00001766
Chris Lattner2b295a02010-01-04 07:53:58 +00001767 if (Instruction *I = commonCastTransforms(CI))
1768 return I;
1769
Craig Topperf40110f2014-04-25 05:29:35 +00001770 return nullptr;
Chris Lattner2b295a02010-01-04 07:53:58 +00001771}
1772
Adrian Prantl4dfcc4a2018-05-01 16:10:38 +00001773/// Implement the transforms for cast of pointer (bitcast/ptrtoint)
Chris Lattnera93c63c2010-01-05 22:21:18 +00001774Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
1775 Value *Src = CI.getOperand(0);
Craig Topper3529aa52013-01-24 05:22:40 +00001776
Chris Lattnera93c63c2010-01-05 22:21:18 +00001777 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
1778 // If casting the result of a getelementptr instruction with no offset, turn
1779 // this into a cast of the original pointer!
Jingyue Wu77145d92014-06-06 21:52:55 +00001780 if (GEP->hasAllZeroIndices() &&
1781 // If CI is an addrspacecast and GEP changes the poiner type, merging
1782 // GEP into CI would undo canonicalizing addrspacecast with different
1783 // pointer types, causing infinite loops.
1784 (!isa<AddrSpaceCastInst>(CI) ||
Sanjoy Dasf09c1e32017-04-18 22:00:54 +00001785 GEP->getType() == GEP->getPointerOperandType())) {
Chris Lattnera93c63c2010-01-05 22:21:18 +00001786 // Changing the cast operand is usually not a good idea but it is safe
Craig Topper3529aa52013-01-24 05:22:40 +00001787 // here because the pointer operand is being replaced with another
Chris Lattnera93c63c2010-01-05 22:21:18 +00001788 // pointer operand so the opcode doesn't need to change.
1789 Worklist.Add(GEP);
1790 CI.setOperand(0, GEP->getOperand(0));
1791 return &CI;
1792 }
Chris Lattnera93c63c2010-01-05 22:21:18 +00001793 }
Craig Topper3529aa52013-01-24 05:22:40 +00001794
Chris Lattnera93c63c2010-01-05 22:21:18 +00001795 return commonCastTransforms(CI);
1796}
1797
1798Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
Dan Gohman949458d2010-02-02 01:44:02 +00001799 // If the destination integer type is not the intptr_t type for this target,
1800 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
1801 // to be exposed to other transforms.
Benjamin Kramere4778752013-02-05 19:21:56 +00001802
Matt Arsenault745101d2013-08-21 19:53:10 +00001803 Type *Ty = CI.getType();
1804 unsigned AS = CI.getPointerAddressSpace();
1805
Elena Demikhovsky945b7e52018-02-14 06:58:08 +00001806 if (Ty->getScalarSizeInBits() == DL.getIndexSizeInBits(AS))
Matt Arsenault745101d2013-08-21 19:53:10 +00001807 return commonPointerCastTransforms(CI);
1808
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001809 Type *PtrTy = DL.getIntPtrType(CI.getContext(), AS);
Matt Arsenault745101d2013-08-21 19:53:10 +00001810 if (Ty->isVectorTy()) // Handle vectors of pointers.
1811 PtrTy = VectorType::get(PtrTy, Ty->getVectorNumElements());
1812
Craig Topperbb4069e2017-07-07 23:16:26 +00001813 Value *P = Builder.CreatePtrToInt(CI.getOperand(0), PtrTy);
Matt Arsenault745101d2013-08-21 19:53:10 +00001814 return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false);
Chris Lattnera93c63c2010-01-05 22:21:18 +00001815}
1816
Sanjay Patel2fbab9d82015-09-09 14:34:26 +00001817/// This input value (which is known to have vector type) is being zero extended
1818/// or truncated to the specified vector type.
1819/// Try to replace it with a shuffle (and vector/vector bitcast) if possible.
Chris Lattner02b0df52010-05-08 21:50:26 +00001820///
1821/// The source and destination vector types may have different element types.
Sanjay Patele2834412015-09-09 14:54:29 +00001822static Instruction *optimizeVectorResize(Value *InVal, VectorType *DestTy,
Chris Lattner02b0df52010-05-08 21:50:26 +00001823 InstCombiner &IC) {
1824 // We can only do this optimization if the output is a multiple of the input
1825 // element size, or the input is a multiple of the output element size.
1826 // Convert the input type to have the same element type as the output.
Chris Lattner229907c2011-07-18 04:54:35 +00001827 VectorType *SrcTy = cast<VectorType>(InVal->getType());
Craig Topper3529aa52013-01-24 05:22:40 +00001828
Chris Lattner02b0df52010-05-08 21:50:26 +00001829 if (SrcTy->getElementType() != DestTy->getElementType()) {
1830 // The input types don't need to be identical, but for now they must be the
1831 // same size. There is no specific reason we couldn't handle things like
1832 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
Craig Topper3529aa52013-01-24 05:22:40 +00001833 // there yet.
Chris Lattner02b0df52010-05-08 21:50:26 +00001834 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
1835 DestTy->getElementType()->getPrimitiveSizeInBits())
Craig Topperf40110f2014-04-25 05:29:35 +00001836 return nullptr;
Craig Topper3529aa52013-01-24 05:22:40 +00001837
Chris Lattner02b0df52010-05-08 21:50:26 +00001838 SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
Craig Topperbb4069e2017-07-07 23:16:26 +00001839 InVal = IC.Builder.CreateBitCast(InVal, SrcTy);
Chris Lattner02b0df52010-05-08 21:50:26 +00001840 }
Craig Topper3529aa52013-01-24 05:22:40 +00001841
Chris Lattner02b0df52010-05-08 21:50:26 +00001842 // Now that the element types match, get the shuffle mask and RHS of the
1843 // shuffle to use, which depends on whether we're increasing or decreasing the
1844 // size of the input.
Chris Lattner8213c8a2012-02-06 21:56:39 +00001845 SmallVector<uint32_t, 16> ShuffleMask;
Chris Lattner02b0df52010-05-08 21:50:26 +00001846 Value *V2;
Craig Topper3529aa52013-01-24 05:22:40 +00001847
Chris Lattner02b0df52010-05-08 21:50:26 +00001848 if (SrcTy->getNumElements() > DestTy->getNumElements()) {
1849 // If we're shrinking the number of elements, just shuffle in the low
1850 // elements from the input and use undef as the second shuffle input.
1851 V2 = UndefValue::get(SrcTy);
1852 for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
Chris Lattner8213c8a2012-02-06 21:56:39 +00001853 ShuffleMask.push_back(i);
Craig Topper3529aa52013-01-24 05:22:40 +00001854
Chris Lattner02b0df52010-05-08 21:50:26 +00001855 } else {
1856 // If we're increasing the number of elements, shuffle in all of the
1857 // elements from InVal and fill the rest of the result elements with zeros
1858 // from a constant zero.
1859 V2 = Constant::getNullValue(SrcTy);
1860 unsigned SrcElts = SrcTy->getNumElements();
1861 for (unsigned i = 0, e = SrcElts; i != e; ++i)
Chris Lattner8213c8a2012-02-06 21:56:39 +00001862 ShuffleMask.push_back(i);
Chris Lattner02b0df52010-05-08 21:50:26 +00001863
1864 // The excess elements reference the first element of the zero input.
Chris Lattner8213c8a2012-02-06 21:56:39 +00001865 for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i)
1866 ShuffleMask.push_back(SrcElts);
Chris Lattner02b0df52010-05-08 21:50:26 +00001867 }
Craig Topper3529aa52013-01-24 05:22:40 +00001868
Chris Lattner8213c8a2012-02-06 21:56:39 +00001869 return new ShuffleVectorInst(InVal, V2,
1870 ConstantDataVector::get(V2->getContext(),
1871 ShuffleMask));
Chris Lattner02b0df52010-05-08 21:50:26 +00001872}
1873
Chris Lattner229907c2011-07-18 04:54:35 +00001874static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
Chris Lattnerdd660102010-08-28 01:20:38 +00001875 return Value % Ty->getPrimitiveSizeInBits() == 0;
1876}
1877
Chris Lattner229907c2011-07-18 04:54:35 +00001878static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
Chris Lattnerdd660102010-08-28 01:20:38 +00001879 return Value / Ty->getPrimitiveSizeInBits();
1880}
1881
Sanjay Patel2fbab9d82015-09-09 14:34:26 +00001882/// V is a value which is inserted into a vector of VecEltTy.
1883/// Look through the value to see if we can decompose it into
Chris Lattnerdd660102010-08-28 01:20:38 +00001884/// insertions into the vector. See the example in the comment for
1885/// OptimizeIntegerToVectorInsertions for the pattern this handles.
1886/// The type of V is always a non-zero multiple of VecEltTy's size.
Richard Sandifordfeb34712013-08-12 07:26:09 +00001887/// Shift is the number of bits between the lsb of V and the lsb of
1888/// the vector.
Chris Lattnerdd660102010-08-28 01:20:38 +00001889///
1890/// This returns false if the pattern can't be matched or true if it can,
1891/// filling in Elements with the elements found here.
Sanjay Patele2834412015-09-09 14:54:29 +00001892static bool collectInsertionElements(Value *V, unsigned Shift,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001893 SmallVectorImpl<Value *> &Elements,
1894 Type *VecEltTy, bool isBigEndian) {
Richard Sandifordfeb34712013-08-12 07:26:09 +00001895 assert(isMultipleOfTypeSize(Shift, VecEltTy) &&
1896 "Shift should be a multiple of the element type size");
1897
Chris Lattner50df36a2010-08-28 03:36:51 +00001898 // Undef values never contribute useful bits to the result.
1899 if (isa<UndefValue>(V)) return true;
Craig Topper3529aa52013-01-24 05:22:40 +00001900
Chris Lattnerdd660102010-08-28 01:20:38 +00001901 // If we got down to a value of the right type, we win, try inserting into the
1902 // right element.
1903 if (V->getType() == VecEltTy) {
Chris Lattnerd0214f32010-08-28 01:50:57 +00001904 // Inserting null doesn't actually insert any elements.
1905 if (Constant *C = dyn_cast<Constant>(V))
1906 if (C->isNullValue())
1907 return true;
Craig Topper3529aa52013-01-24 05:22:40 +00001908
Richard Sandifordfeb34712013-08-12 07:26:09 +00001909 unsigned ElementIndex = getTypeSizeIndex(Shift, VecEltTy);
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001910 if (isBigEndian)
Richard Sandifordfeb34712013-08-12 07:26:09 +00001911 ElementIndex = Elements.size() - ElementIndex - 1;
1912
Chris Lattnerdd660102010-08-28 01:20:38 +00001913 // Fail if multiple elements are inserted into this slot.
Craig Topperf40110f2014-04-25 05:29:35 +00001914 if (Elements[ElementIndex])
Chris Lattnerdd660102010-08-28 01:20:38 +00001915 return false;
Craig Topper3529aa52013-01-24 05:22:40 +00001916
Chris Lattnerdd660102010-08-28 01:20:38 +00001917 Elements[ElementIndex] = V;
1918 return true;
1919 }
Craig Topper3529aa52013-01-24 05:22:40 +00001920
Chris Lattnerd0214f32010-08-28 01:50:57 +00001921 if (Constant *C = dyn_cast<Constant>(V)) {
Chris Lattnerdd660102010-08-28 01:20:38 +00001922 // Figure out the # elements this provides, and bitcast it or slice it up
1923 // as required.
Chris Lattnerd0214f32010-08-28 01:50:57 +00001924 unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
1925 VecEltTy);
1926 // If the constant is the size of a vector element, we just need to bitcast
1927 // it to the right type so it gets properly inserted.
1928 if (NumElts == 1)
Sanjay Patele2834412015-09-09 14:54:29 +00001929 return collectInsertionElements(ConstantExpr::getBitCast(C, VecEltTy),
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001930 Shift, Elements, VecEltTy, isBigEndian);
Craig Topper3529aa52013-01-24 05:22:40 +00001931
Chris Lattnerd0214f32010-08-28 01:50:57 +00001932 // Okay, this is a constant that covers multiple elements. Slice it up into
1933 // pieces and insert each element-sized piece into the vector.
1934 if (!isa<IntegerType>(C->getType()))
1935 C = ConstantExpr::getBitCast(C, IntegerType::get(V->getContext(),
1936 C->getType()->getPrimitiveSizeInBits()));
1937 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
Chris Lattner229907c2011-07-18 04:54:35 +00001938 Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
Craig Topper3529aa52013-01-24 05:22:40 +00001939
Chris Lattnerd0214f32010-08-28 01:50:57 +00001940 for (unsigned i = 0; i != NumElts; ++i) {
Richard Sandifordfeb34712013-08-12 07:26:09 +00001941 unsigned ShiftI = Shift+i*ElementSize;
Chris Lattnerd0214f32010-08-28 01:50:57 +00001942 Constant *Piece = ConstantExpr::getLShr(C, ConstantInt::get(C->getType(),
Richard Sandifordfeb34712013-08-12 07:26:09 +00001943 ShiftI));
Chris Lattnerd0214f32010-08-28 01:50:57 +00001944 Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
Sanjay Patele2834412015-09-09 14:54:29 +00001945 if (!collectInsertionElements(Piece, ShiftI, Elements, VecEltTy,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001946 isBigEndian))
Chris Lattnerd0214f32010-08-28 01:50:57 +00001947 return false;
1948 }
1949 return true;
1950 }
Craig Topper3529aa52013-01-24 05:22:40 +00001951
Chris Lattnerdd660102010-08-28 01:20:38 +00001952 if (!V->hasOneUse()) return false;
Craig Topper3529aa52013-01-24 05:22:40 +00001953
Chris Lattnerdd660102010-08-28 01:20:38 +00001954 Instruction *I = dyn_cast<Instruction>(V);
Craig Topperf40110f2014-04-25 05:29:35 +00001955 if (!I) return false;
Chris Lattnerdd660102010-08-28 01:20:38 +00001956 switch (I->getOpcode()) {
1957 default: return false; // Unhandled case.
1958 case Instruction::BitCast:
Sanjay Patele2834412015-09-09 14:54:29 +00001959 return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001960 isBigEndian);
Chris Lattnerdd660102010-08-28 01:20:38 +00001961 case Instruction::ZExt:
1962 if (!isMultipleOfTypeSize(
1963 I->getOperand(0)->getType()->getPrimitiveSizeInBits(),
1964 VecEltTy))
1965 return false;
Sanjay Patele2834412015-09-09 14:54:29 +00001966 return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001967 isBigEndian);
Chris Lattnerdd660102010-08-28 01:20:38 +00001968 case Instruction::Or:
Sanjay Patele2834412015-09-09 14:54:29 +00001969 return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001970 isBigEndian) &&
Sanjay Patele2834412015-09-09 14:54:29 +00001971 collectInsertionElements(I->getOperand(1), Shift, Elements, VecEltTy,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001972 isBigEndian);
Chris Lattnerdd660102010-08-28 01:20:38 +00001973 case Instruction::Shl: {
1974 // Must be shifting by a constant that is a multiple of the element size.
1975 ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1));
Craig Topperf40110f2014-04-25 05:29:35 +00001976 if (!CI) return false;
Richard Sandifordfeb34712013-08-12 07:26:09 +00001977 Shift += CI->getZExtValue();
1978 if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false;
Sanjay Patele2834412015-09-09 14:54:29 +00001979 return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00001980 isBigEndian);
Chris Lattnerdd660102010-08-28 01:20:38 +00001981 }
Craig Topper3529aa52013-01-24 05:22:40 +00001982
Chris Lattnerdd660102010-08-28 01:20:38 +00001983 }
1984}
1985
1986
Sanjay Patel2fbab9d82015-09-09 14:34:26 +00001987/// If the input is an 'or' instruction, we may be doing shifts and ors to
1988/// assemble the elements of the vector manually.
Chris Lattnerdd660102010-08-28 01:20:38 +00001989/// Try to rip the code out and replace it with insertelements. This is to
1990/// optimize code like this:
1991///
1992/// %tmp37 = bitcast float %inc to i32
1993/// %tmp38 = zext i32 %tmp37 to i64
1994/// %tmp31 = bitcast float %inc5 to i32
1995/// %tmp32 = zext i32 %tmp31 to i64
1996/// %tmp33 = shl i64 %tmp32, 32
1997/// %ins35 = or i64 %tmp33, %tmp38
1998/// %tmp43 = bitcast i64 %ins35 to <2 x float>
1999///
2000/// Into two insertelements that do "buildvector{%inc, %inc5}".
Sanjay Patele2834412015-09-09 14:54:29 +00002001static Value *optimizeIntegerToVectorInsertions(BitCastInst &CI,
Chris Lattnerdd660102010-08-28 01:20:38 +00002002 InstCombiner &IC) {
Chris Lattner229907c2011-07-18 04:54:35 +00002003 VectorType *DestVecTy = cast<VectorType>(CI.getType());
Chris Lattnerdd660102010-08-28 01:20:38 +00002004 Value *IntInput = CI.getOperand(0);
2005
2006 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
Sanjay Patele2834412015-09-09 14:54:29 +00002007 if (!collectInsertionElements(IntInput, 0, Elements,
Mehdi Aminia28d91d2015-03-10 02:37:25 +00002008 DestVecTy->getElementType(),
2009 IC.getDataLayout().isBigEndian()))
Craig Topperf40110f2014-04-25 05:29:35 +00002010 return nullptr;
Chris Lattnerdd660102010-08-28 01:20:38 +00002011
2012 // If we succeeded, we know that all of the element are specified by Elements
2013 // or are zero if Elements has a null entry. Recast this as a set of
2014 // insertions.
2015 Value *Result = Constant::getNullValue(CI.getType());
2016 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
Craig Topperf40110f2014-04-25 05:29:35 +00002017 if (!Elements[i]) continue; // Unset element.
Craig Topper3529aa52013-01-24 05:22:40 +00002018
Craig Topperbb4069e2017-07-07 23:16:26 +00002019 Result = IC.Builder.CreateInsertElement(Result, Elements[i],
2020 IC.Builder.getInt32(i));
Chris Lattnerdd660102010-08-28 01:20:38 +00002021 }
Craig Topper3529aa52013-01-24 05:22:40 +00002022
Chris Lattnerdd660102010-08-28 01:20:38 +00002023 return Result;
2024}
2025
Sanjay Patel1d49fc92015-12-12 16:44:48 +00002026/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
2027/// vector followed by extract element. The backend tends to handle bitcasts of
2028/// vectors better than bitcasts of scalars because vector registers are
2029/// usually not type-specific like scalar integer or scalar floating-point.
2030static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast,
Craig Toppercb220392017-07-06 23:18:43 +00002031 InstCombiner &IC) {
Sanjay Patelc83fd952015-12-10 17:09:28 +00002032 // TODO: Create and use a pattern matcher for ExtractElementInst.
2033 auto *ExtElt = dyn_cast<ExtractElementInst>(BitCast.getOperand(0));
2034 if (!ExtElt || !ExtElt->hasOneUse())
2035 return nullptr;
2036
Sanjay Patel1d49fc92015-12-12 16:44:48 +00002037 // The bitcast must be to a vectorizable type, otherwise we can't make a new
2038 // type to extract from.
2039 Type *DestType = BitCast.getType();
2040 if (!VectorType::isValidElementType(DestType))
Sanjay Patelc83fd952015-12-10 17:09:28 +00002041 return nullptr;
2042
Sanjay Patel1d49fc92015-12-12 16:44:48 +00002043 unsigned NumElts = ExtElt->getVectorOperandType()->getNumElements();
2044 auto *NewVecType = VectorType::get(DestType, NumElts);
Craig Topperbb4069e2017-07-07 23:16:26 +00002045 auto *NewBC = IC.Builder.CreateBitCast(ExtElt->getVectorOperand(),
2046 NewVecType, "bc");
Sanjay Patel1d49fc92015-12-12 16:44:48 +00002047 return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand());
Sanjay Patelc83fd952015-12-10 17:09:28 +00002048}
2049
Sanjay Patele359eaa2016-11-22 22:05:48 +00002050/// Change the type of a bitwise logic operation if we can eliminate a bitcast.
2051static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast,
2052 InstCombiner::BuilderTy &Builder) {
Sanjay Patele359eaa2016-11-22 22:05:48 +00002053 Type *DestTy = BitCast.getType();
Sanjay Patel1e6ca442016-11-22 22:54:36 +00002054 BinaryOperator *BO;
Craig Topper95d23472017-07-09 07:04:00 +00002055 if (!DestTy->isIntOrIntVectorTy() ||
Sanjay Patel1e6ca442016-11-22 22:54:36 +00002056 !match(BitCast.getOperand(0), m_OneUse(m_BinOp(BO))) ||
2057 !BO->isBitwiseLogicOp())
Sanjay Patele359eaa2016-11-22 22:05:48 +00002058 return nullptr;
Elena Demikhovsky945b7e52018-02-14 06:58:08 +00002059
Sanjay Patele359eaa2016-11-22 22:05:48 +00002060 // FIXME: This transform is restricted to vector types to avoid backend
2061 // problems caused by creating potentially illegal operations. If a fix-up is
2062 // added to handle that situation, we can remove this check.
2063 if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy())
2064 return nullptr;
Elena Demikhovsky945b7e52018-02-14 06:58:08 +00002065
Sanjay Patele359eaa2016-11-22 22:05:48 +00002066 Value *X;
2067 if (match(BO->getOperand(0), m_OneUse(m_BitCast(m_Value(X)))) &&
2068 X->getType() == DestTy && !isa<Constant>(X)) {
2069 // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y))
2070 Value *CastedOp1 = Builder.CreateBitCast(BO->getOperand(1), DestTy);
Sanjay Patel1e6ca442016-11-22 22:54:36 +00002071 return BinaryOperator::Create(BO->getOpcode(), X, CastedOp1);
Sanjay Patele359eaa2016-11-22 22:05:48 +00002072 }
2073
2074 if (match(BO->getOperand(1), m_OneUse(m_BitCast(m_Value(X)))) &&
2075 X->getType() == DestTy && !isa<Constant>(X)) {
2076 // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X)
2077 Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
Sanjay Patel1e6ca442016-11-22 22:54:36 +00002078 return BinaryOperator::Create(BO->getOpcode(), CastedOp0, X);
Sanjay Patele359eaa2016-11-22 22:05:48 +00002079 }
2080
Sanjay Pateld1e81192017-06-22 15:46:54 +00002081 // Canonicalize vector bitcasts to come before vector bitwise logic with a
2082 // constant. This eases recognition of special constants for later ops.
2083 // Example:
2084 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
2085 Constant *C;
2086 if (match(BO->getOperand(1), m_Constant(C))) {
2087 // bitcast (logic X, C) --> logic (bitcast X, C')
2088 Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
2089 Value *CastedC = ConstantExpr::getBitCast(C, DestTy);
2090 return BinaryOperator::Create(BO->getOpcode(), CastedOp0, CastedC);
2091 }
2092
Sanjay Patele359eaa2016-11-22 22:05:48 +00002093 return nullptr;
2094}
2095
Sanjay Patelb7f8cb62016-12-03 15:25:16 +00002096/// Change the type of a select if we can eliminate a bitcast.
2097static Instruction *foldBitCastSelect(BitCastInst &BitCast,
2098 InstCombiner::BuilderTy &Builder) {
2099 Value *Cond, *TVal, *FVal;
2100 if (!match(BitCast.getOperand(0),
2101 m_OneUse(m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))))
2102 return nullptr;
2103
2104 // A vector select must maintain the same number of elements in its operands.
2105 Type *CondTy = Cond->getType();
2106 Type *DestTy = BitCast.getType();
2107 if (CondTy->isVectorTy()) {
2108 if (!DestTy->isVectorTy())
2109 return nullptr;
2110 if (DestTy->getVectorNumElements() != CondTy->getVectorNumElements())
2111 return nullptr;
2112 }
2113
2114 // FIXME: This transform is restricted from changing the select between
2115 // scalars and vectors to avoid backend problems caused by creating
2116 // potentially illegal operations. If a fix-up is added to handle that
2117 // situation, we can remove this check.
2118 if (DestTy->isVectorTy() != TVal->getType()->isVectorTy())
2119 return nullptr;
2120
2121 auto *Sel = cast<Instruction>(BitCast.getOperand(0));
2122 Value *X;
2123 if (match(TVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2124 !isa<Constant>(X)) {
2125 // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y))
2126 Value *CastedVal = Builder.CreateBitCast(FVal, DestTy);
2127 return SelectInst::Create(Cond, X, CastedVal, "", nullptr, Sel);
2128 }
2129
2130 if (match(FVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy &&
2131 !isa<Constant>(X)) {
2132 // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X)
2133 Value *CastedVal = Builder.CreateBitCast(TVal, DestTy);
2134 return SelectInst::Create(Cond, CastedVal, X, "", nullptr, Sel);
2135 }
2136
2137 return nullptr;
2138}
2139
Guozhi Weiae541f62016-10-25 20:43:42 +00002140/// Check if all users of CI are StoreInsts.
2141static bool hasStoreUsersOnly(CastInst &CI) {
2142 for (User *U : CI.users()) {
2143 if (!isa<StoreInst>(U))
2144 return false;
2145 }
2146 return true;
2147}
2148
2149/// This function handles following case
2150///
2151/// A -> B cast
2152/// PHI
2153/// B -> A cast
2154///
2155/// All the related PHI nodes can be replaced by new PHI nodes with type A.
2156/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN.
2157Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
2158 // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp.
2159 if (hasStoreUsersOnly(CI))
2160 return nullptr;
2161
2162 Value *Src = CI.getOperand(0);
2163 Type *SrcTy = Src->getType(); // Type B
2164 Type *DestTy = CI.getType(); // Type A
2165
2166 SmallVector<PHINode *, 4> PhiWorklist;
2167 SmallSetVector<PHINode *, 4> OldPhiNodes;
2168
2169 // Find all of the A->B casts and PHI nodes.
2170 // We need to inpect all related PHI nodes, but PHIs can be cyclic, so
2171 // OldPhiNodes is used to track all known PHI nodes, before adding a new
2172 // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
2173 PhiWorklist.push_back(PN);
2174 OldPhiNodes.insert(PN);
2175 while (!PhiWorklist.empty()) {
2176 auto *OldPN = PhiWorklist.pop_back_val();
2177 for (Value *IncValue : OldPN->incoming_values()) {
2178 if (isa<Constant>(IncValue))
2179 continue;
2180
2181 if (auto *LI = dyn_cast<LoadInst>(IncValue)) {
2182 // If there is a sequence of one or more load instructions, each loaded
2183 // value is used as address of later load instruction, bitcast is
2184 // necessary to change the value type, don't optimize it. For
2185 // simplicity we give up if the load address comes from another load.
2186 Value *Addr = LI->getOperand(0);
2187 if (Addr == &CI || isa<LoadInst>(Addr))
2188 return nullptr;
2189 if (LI->hasOneUse() && LI->isSimple())
2190 continue;
2191 // If a LoadInst has more than one use, changing the type of loaded
2192 // value may create another bitcast.
2193 return nullptr;
2194 }
2195
2196 if (auto *PNode = dyn_cast<PHINode>(IncValue)) {
2197 if (OldPhiNodes.insert(PNode))
2198 PhiWorklist.push_back(PNode);
2199 continue;
2200 }
2201
2202 auto *BCI = dyn_cast<BitCastInst>(IncValue);
2203 // We can't handle other instructions.
2204 if (!BCI)
2205 return nullptr;
2206
2207 // Verify it's a A->B cast.
2208 Type *TyA = BCI->getOperand(0)->getType();
2209 Type *TyB = BCI->getType();
2210 if (TyA != DestTy || TyB != SrcTy)
2211 return nullptr;
2212 }
2213 }
2214
2215 // For each old PHI node, create a corresponding new PHI node with a type A.
2216 SmallDenseMap<PHINode *, PHINode *> NewPNodes;
2217 for (auto *OldPN : OldPhiNodes) {
Craig Topperbb4069e2017-07-07 23:16:26 +00002218 Builder.SetInsertPoint(OldPN);
2219 PHINode *NewPN = Builder.CreatePHI(DestTy, OldPN->getNumOperands());
Guozhi Weiae541f62016-10-25 20:43:42 +00002220 NewPNodes[OldPN] = NewPN;
2221 }
2222
2223 // Fill in the operands of new PHI nodes.
2224 for (auto *OldPN : OldPhiNodes) {
2225 PHINode *NewPN = NewPNodes[OldPN];
2226 for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) {
2227 Value *V = OldPN->getOperand(j);
2228 Value *NewV = nullptr;
2229 if (auto *C = dyn_cast<Constant>(V)) {
2230 NewV = ConstantExpr::getBitCast(C, DestTy);
2231 } else if (auto *LI = dyn_cast<LoadInst>(V)) {
Craig Topperbb4069e2017-07-07 23:16:26 +00002232 Builder.SetInsertPoint(LI->getNextNode());
2233 NewV = Builder.CreateBitCast(LI, DestTy);
Guozhi Weiae541f62016-10-25 20:43:42 +00002234 Worklist.Add(LI);
2235 } else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
2236 NewV = BCI->getOperand(0);
2237 } else if (auto *PrevPN = dyn_cast<PHINode>(V)) {
2238 NewV = NewPNodes[PrevPN];
2239 }
2240 assert(NewV);
2241 NewPN->addIncoming(NewV, OldPN->getIncomingBlock(j));
2242 }
2243 }
2244
2245 // If there is a store with type B, change it to type A.
2246 for (User *U : PN->users()) {
2247 auto *SI = dyn_cast<StoreInst>(U);
2248 if (SI && SI->isSimple() && SI->getOperand(0) == PN) {
Craig Topperbb4069e2017-07-07 23:16:26 +00002249 Builder.SetInsertPoint(SI);
Guozhi Weiae541f62016-10-25 20:43:42 +00002250 auto *NewBC =
Craig Topperbb4069e2017-07-07 23:16:26 +00002251 cast<BitCastInst>(Builder.CreateBitCast(NewPNodes[PN], SrcTy));
Guozhi Weiae541f62016-10-25 20:43:42 +00002252 SI->setOperand(0, NewBC);
2253 Worklist.Add(SI);
2254 assert(hasStoreUsersOnly(*NewBC));
2255 }
2256 }
2257
2258 return replaceInstUsesWith(CI, NewPNodes[PN]);
2259}
2260
Chris Lattner2b295a02010-01-04 07:53:58 +00002261Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
2262 // If the operands are integer typed then apply the integer transforms,
2263 // otherwise just apply the common ones.
2264 Value *Src = CI.getOperand(0);
Chris Lattner229907c2011-07-18 04:54:35 +00002265 Type *SrcTy = Src->getType();
2266 Type *DestTy = CI.getType();
Chris Lattner2b295a02010-01-04 07:53:58 +00002267
Chris Lattner2b295a02010-01-04 07:53:58 +00002268 // Get rid of casts from one type to the same type. These are useless and can
2269 // be replaced by the operand.
2270 if (DestTy == Src->getType())
Sanjay Patel4b198802016-02-01 22:23:39 +00002271 return replaceInstUsesWith(CI, Src);
Chris Lattner2b295a02010-01-04 07:53:58 +00002272
Chris Lattner229907c2011-07-18 04:54:35 +00002273 if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
2274 PointerType *SrcPTy = cast<PointerType>(SrcTy);
2275 Type *DstElTy = DstPTy->getElementType();
2276 Type *SrcElTy = SrcPTy->getElementType();
Craig Topper3529aa52013-01-24 05:22:40 +00002277
Ewan Crawfordd83beb82018-07-31 15:53:03 +00002278 // Casting pointers between the same type, but with different address spaces
2279 // is an addrspace cast rather than a bitcast.
2280 if ((DstElTy == SrcElTy) &&
2281 (DstPTy->getAddressSpace() != SrcPTy->getAddressSpace()))
2282 return new AddrSpaceCastInst(Src, DestTy);
2283
Chris Lattner2b295a02010-01-04 07:53:58 +00002284 // If we are casting a alloca to a pointer to a type of the same
2285 // size, rewrite the allocation instruction to allocate the "right" type.
2286 // There is no need to modify malloc calls because it is their bitcast that
2287 // needs to be cleaned up.
2288 if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
2289 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
2290 return V;
Craig Topper3529aa52013-01-24 05:22:40 +00002291
Gerolf Hoflehner00e70922016-05-23 19:23:17 +00002292 // When the type pointed to is not sized the cast cannot be
2293 // turned into a gep.
2294 Type *PointeeType =
2295 cast<PointerType>(Src->getType()->getScalarType())->getElementType();
2296 if (!PointeeType->isSized())
2297 return nullptr;
2298
Chris Lattner2b295a02010-01-04 07:53:58 +00002299 // If the source and destination are pointers, and this cast is equivalent
2300 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
2301 // This can enhance SROA and other transforms that want type-safe pointers.
Chris Lattner2b295a02010-01-04 07:53:58 +00002302 unsigned NumZeros = 0;
Craig Topper3529aa52013-01-24 05:22:40 +00002303 while (SrcElTy != DstElTy &&
Duncan Sands19d0b472010-02-16 11:11:14 +00002304 isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
Chris Lattner2b295a02010-01-04 07:53:58 +00002305 SrcElTy->getNumContainedTypes() /* not "{}" */) {
Benjamin Kramer2a7404a2015-04-18 16:52:08 +00002306 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U);
Chris Lattner2b295a02010-01-04 07:53:58 +00002307 ++NumZeros;
2308 }
2309
2310 // If we found a path from the src to dest, create the getelementptr now.
2311 if (SrcElTy == DstElTy) {
Craig Topperbb4069e2017-07-07 23:16:26 +00002312 SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
Jay Foadd1b78492011-07-25 09:48:08 +00002313 return GetElementPtrInst::CreateInBounds(Src, Idxs);
Chris Lattner2b295a02010-01-04 07:53:58 +00002314 }
2315 }
Craig Topper3529aa52013-01-24 05:22:40 +00002316
Chris Lattner229907c2011-07-18 04:54:35 +00002317 if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
Duncan Sands19d0b472010-02-16 11:11:14 +00002318 if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
Craig Topperbb4069e2017-07-07 23:16:26 +00002319 Value *Elem = Builder.CreateBitCast(Src, DestVTy->getElementType());
Chris Lattnera93c63c2010-01-05 22:21:18 +00002320 return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
Chris Lattner2b295a02010-01-04 07:53:58 +00002321 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
Chris Lattner2b295a02010-01-04 07:53:58 +00002322 // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
2323 }
Craig Topper3529aa52013-01-24 05:22:40 +00002324
Chris Lattnerdd660102010-08-28 01:20:38 +00002325 if (isa<IntegerType>(SrcTy)) {
2326 // If this is a cast from an integer to vector, check to see if the input
2327 // is a trunc or zext of a bitcast from vector. If so, we can replace all
2328 // the casts with a shuffle and (potentially) a bitcast.
2329 if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
2330 CastInst *SrcCast = cast<CastInst>(Src);
2331 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
2332 if (isa<VectorType>(BCIn->getOperand(0)->getType()))
Sanjay Patele2834412015-09-09 14:54:29 +00002333 if (Instruction *I = optimizeVectorResize(BCIn->getOperand(0),
Chris Lattner02b0df52010-05-08 21:50:26 +00002334 cast<VectorType>(DestTy), *this))
Chris Lattnerdd660102010-08-28 01:20:38 +00002335 return I;
2336 }
Craig Topper3529aa52013-01-24 05:22:40 +00002337
Chris Lattnerdd660102010-08-28 01:20:38 +00002338 // If the input is an 'or' instruction, we may be doing shifts and ors to
2339 // assemble the elements of the vector manually. Try to rip the code out
2340 // and replace it with insertelements.
Sanjay Patele2834412015-09-09 14:54:29 +00002341 if (Value *V = optimizeIntegerToVectorInsertions(CI, *this))
Sanjay Patel4b198802016-02-01 22:23:39 +00002342 return replaceInstUsesWith(CI, V);
Chris Lattner02b0df52010-05-08 21:50:26 +00002343 }
Chris Lattner2b295a02010-01-04 07:53:58 +00002344 }
2345
Chris Lattner229907c2011-07-18 04:54:35 +00002346 if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
Michael Ilseman74a6da92013-02-11 21:41:44 +00002347 if (SrcVTy->getNumElements() == 1) {
2348 // If our destination is not a vector, then make this a straight
2349 // scalar-scalar cast.
2350 if (!DestTy->isVectorTy()) {
2351 Value *Elem =
Craig Topperbb4069e2017-07-07 23:16:26 +00002352 Builder.CreateExtractElement(Src,
Michael Ilseman74a6da92013-02-11 21:41:44 +00002353 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
2354 return CastInst::Create(Instruction::BitCast, Elem, DestTy);
2355 }
2356
2357 // Otherwise, see if our source is an insert. If so, then use the scalar
2358 // component directly.
2359 if (InsertElementInst *IEI =
2360 dyn_cast<InsertElementInst>(CI.getOperand(0)))
2361 return CastInst::Create(Instruction::BitCast, IEI->getOperand(1),
2362 DestTy);
Chris Lattner2b295a02010-01-04 07:53:58 +00002363 }
2364 }
2365
2366 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
Chris Lattnera93c63c2010-01-05 22:21:18 +00002367 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
Dan Gohmaneb7111b2010-04-07 23:22:42 +00002368 // a bitcast to a vector with the same # elts.
Craig Topper3529aa52013-01-24 05:22:40 +00002369 if (SVI->hasOneUse() && DestTy->isVectorTy() &&
Matt Arsenaultfc00f7e2013-08-14 00:24:34 +00002370 DestTy->getVectorNumElements() == SVI->getType()->getNumElements() &&
Chris Lattnera93c63c2010-01-05 22:21:18 +00002371 SVI->getType()->getNumElements() ==
Matt Arsenaultfc00f7e2013-08-14 00:24:34 +00002372 SVI->getOperand(0)->getType()->getVectorNumElements()) {
Chris Lattnera93c63c2010-01-05 22:21:18 +00002373 BitCastInst *Tmp;
2374 // If either of the operands is a cast from CI.getType(), then
2375 // evaluating the shuffle in the casted destination's type will allow
2376 // us to eliminate at least one cast.
Craig Topper3529aa52013-01-24 05:22:40 +00002377 if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
Chris Lattnera93c63c2010-01-05 22:21:18 +00002378 Tmp->getOperand(0)->getType() == DestTy) ||
Craig Topper3529aa52013-01-24 05:22:40 +00002379 ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
Chris Lattnera93c63c2010-01-05 22:21:18 +00002380 Tmp->getOperand(0)->getType() == DestTy)) {
Craig Topperbb4069e2017-07-07 23:16:26 +00002381 Value *LHS = Builder.CreateBitCast(SVI->getOperand(0), DestTy);
2382 Value *RHS = Builder.CreateBitCast(SVI->getOperand(1), DestTy);
Chris Lattnera93c63c2010-01-05 22:21:18 +00002383 // Return a new shuffle vector. Use the same element ID's, as we
2384 // know the vector types match #elts.
2385 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
Chris Lattner2b295a02010-01-04 07:53:58 +00002386 }
2387 }
2388 }
Craig Topper3529aa52013-01-24 05:22:40 +00002389
Guozhi Weiae541f62016-10-25 20:43:42 +00002390 // Handle the A->B->A cast, and there is an intervening PHI node.
2391 if (PHINode *PN = dyn_cast<PHINode>(Src))
2392 if (Instruction *I = optimizeBitCastFromPhi(CI, PN))
2393 return I;
2394
Craig Toppercb220392017-07-06 23:18:43 +00002395 if (Instruction *I = canonicalizeBitCastExtElt(CI, *this))
Sanjay Patelc83fd952015-12-10 17:09:28 +00002396 return I;
2397
Craig Topperbb4069e2017-07-07 23:16:26 +00002398 if (Instruction *I = foldBitCastBitwiseLogic(CI, Builder))
Sanjay Patele359eaa2016-11-22 22:05:48 +00002399 return I;
2400
Craig Topperbb4069e2017-07-07 23:16:26 +00002401 if (Instruction *I = foldBitCastSelect(CI, Builder))
Sanjay Patelb7f8cb62016-12-03 15:25:16 +00002402 return I;
2403
Duncan Sands19d0b472010-02-16 11:11:14 +00002404 if (SrcTy->isPointerTy())
Chris Lattnera93c63c2010-01-05 22:21:18 +00002405 return commonPointerCastTransforms(CI);
2406 return commonCastTransforms(CI);
Chris Lattner2b295a02010-01-04 07:53:58 +00002407}
Matt Arsenaulta9e95ab2013-11-15 05:45:08 +00002408
2409Instruction *InstCombiner::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
Manuel Jacobb4db99c2014-07-16 01:34:21 +00002410 // If the destination pointer element type is not the same as the source's
2411 // first do a bitcast to the destination type, and then the addrspacecast.
2412 // This allows the cast to be exposed to other transforms.
Jingyue Wu77145d92014-06-06 21:52:55 +00002413 Value *Src = CI.getOperand(0);
2414 PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
2415 PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
2416
2417 Type *DestElemTy = DestTy->getElementType();
2418 if (SrcTy->getElementType() != DestElemTy) {
2419 Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
Jingyue Wubaabe502014-06-15 21:40:57 +00002420 if (VectorType *VT = dyn_cast<VectorType>(CI.getType())) {
2421 // Handle vectors of pointers.
2422 MidTy = VectorType::get(MidTy, VT->getNumElements());
2423 }
Jingyue Wu77145d92014-06-06 21:52:55 +00002424
Craig Topperbb4069e2017-07-07 23:16:26 +00002425 Value *NewBitCast = Builder.CreateBitCast(Src, MidTy);
Jingyue Wu77145d92014-06-06 21:52:55 +00002426 return new AddrSpaceCastInst(NewBitCast, CI.getType());
2427 }
2428
Matt Arsenault2d353d12014-01-14 20:00:45 +00002429 return commonPointerCastTransforms(CI);
Matt Arsenaulta9e95ab2013-11-15 05:45:08 +00002430}