1 //===- InstCombineCasts.cpp -----------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the visit functions for cast operations.
12 //===----------------------------------------------------------------------===//
14 #include "InstCombine.h"
15 #include "llvm/Analysis/ConstantFolding.h"
16 #include "llvm/IR/DataLayout.h"
17 #include "llvm/Support/PatternMatch.h"
18 #include "llvm/Target/TargetLibraryInfo.h"
20 using namespace PatternMatch;
22 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
23 /// expression. If so, decompose it, returning some value X, such that Val is
26 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
28 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
29 Offset = CI->getZExtValue();
31 return ConstantInt::get(Val->getType(), 0);
34 if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
35 // Cannot look past anything that might overflow.
36 OverflowingBinaryOperator *OBI = dyn_cast<OverflowingBinaryOperator>(Val);
37 if (OBI && !OBI->hasNoUnsignedWrap() && !OBI->hasNoSignedWrap()) {
43 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
44 if (I->getOpcode() == Instruction::Shl) {
45 // This is a value scaled by '1 << the shift amt'.
46 Scale = UINT64_C(1) << RHS->getZExtValue();
48 return I->getOperand(0);
51 if (I->getOpcode() == Instruction::Mul) {
52 // This value is scaled by 'RHS'.
53 Scale = RHS->getZExtValue();
55 return I->getOperand(0);
58 if (I->getOpcode() == Instruction::Add) {
59 // We have X+C. Check to see if we really have (X*C2)+C1,
60 // where C1 is divisible by C2.
63 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
64 Offset += RHS->getZExtValue();
71 // Otherwise, we can't look past this.
77 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
78 /// try to eliminate the cast by moving the type information into the alloc.
79 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
81 // This requires DataLayout to get the alloca alignment and size information.
84 PointerType *PTy = cast<PointerType>(CI.getType());
86 BuilderTy AllocaBuilder(*Builder);
87 AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
89 // Get the type really allocated and the type casted to.
90 Type *AllocElTy = AI.getAllocatedType();
91 Type *CastElTy = PTy->getElementType();
92 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
94 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
95 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
96 if (CastElTyAlign < AllocElTyAlign) return 0;
98 // If the allocation has multiple uses, only promote it if we are strictly
99 // increasing the alignment of the resultant allocation. If we keep it the
100 // same, we open the door to infinite loops of various kinds.
101 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
103 uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
104 uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
105 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
107 // See if we can satisfy the modulus by pulling a scale out of the array
109 unsigned ArraySizeScale;
110 uint64_t ArrayOffset;
111 Value *NumElements = // See if the array size is a decomposable linear expr.
112 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
114 // If we can now satisfy the modulus, by using a non-1 scale, we really can
116 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
117 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
119 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
124 Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale);
125 // Insert before the alloca, not before the cast.
126 Amt = AllocaBuilder.CreateMul(Amt, NumElements);
129 if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
130 Value *Off = ConstantInt::get(AI.getArraySize()->getType(),
132 Amt = AllocaBuilder.CreateAdd(Amt, Off);
135 AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
136 New->setAlignment(AI.getAlignment());
139 // If the allocation has multiple real uses, insert a cast and change all
140 // things that used it to use the new cast. This will also hack on CI, but it
142 if (!AI.hasOneUse()) {
143 // New is the allocation instruction, pointer typed. AI is the original
144 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
145 Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
146 ReplaceInstUsesWith(AI, NewCast);
148 return ReplaceInstUsesWith(CI, New);
151 /// EvaluateInDifferentType - Given an expression that
152 /// CanEvaluateTruncated or CanEvaluateSExtd returns true for, actually
153 /// insert the code to evaluate the expression.
154 Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty,
156 if (Constant *C = dyn_cast<Constant>(V)) {
157 C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
158 // If we got a constantexpr back, try to simplify it with TD info.
159 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
160 C = ConstantFoldConstantExpression(CE, TD, TLI);
164 // Otherwise, it must be an instruction.
165 Instruction *I = cast<Instruction>(V);
166 Instruction *Res = 0;
167 unsigned Opc = I->getOpcode();
169 case Instruction::Add:
170 case Instruction::Sub:
171 case Instruction::Mul:
172 case Instruction::And:
173 case Instruction::Or:
174 case Instruction::Xor:
175 case Instruction::AShr:
176 case Instruction::LShr:
177 case Instruction::Shl:
178 case Instruction::UDiv:
179 case Instruction::URem: {
180 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
181 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
182 Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
185 case Instruction::Trunc:
186 case Instruction::ZExt:
187 case Instruction::SExt:
188 // If the source type of the cast is the type we're trying for then we can
189 // just return the source. There's no need to insert it because it is not
191 if (I->getOperand(0)->getType() == Ty)
192 return I->getOperand(0);
194 // Otherwise, must be the same type of cast, so just reinsert a new one.
195 // This also handles the case of zext(trunc(x)) -> zext(x).
196 Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
197 Opc == Instruction::SExt);
199 case Instruction::Select: {
200 Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
201 Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
202 Res = SelectInst::Create(I->getOperand(0), True, False);
205 case Instruction::PHI: {
206 PHINode *OPN = cast<PHINode>(I);
207 PHINode *NPN = PHINode::Create(Ty, OPN->getNumIncomingValues());
208 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
209 Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
210 NPN->addIncoming(V, OPN->getIncomingBlock(i));
216 // TODO: Can handle more cases here.
217 llvm_unreachable("Unreachable!");
221 return InsertNewInstWith(Res, *I);
225 /// This function is a wrapper around CastInst::isEliminableCastPair. It
226 /// simply extracts arguments and returns what that function returns.
227 static Instruction::CastOps
228 isEliminableCastPair(
229 const CastInst *CI, ///< The first cast instruction
230 unsigned opcode, ///< The opcode of the second cast instruction
231 Type *DstTy, ///< The target type for the second cast instruction
232 DataLayout *TD ///< The target data for pointer size
235 Type *SrcTy = CI->getOperand(0)->getType(); // A from above
236 Type *MidTy = CI->getType(); // B from above
238 // Get the opcodes of the two Cast instructions
239 Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
240 Instruction::CastOps secondOp = Instruction::CastOps(opcode);
241 Type *SrcIntPtrTy = TD && SrcTy->isPtrOrPtrVectorTy() ?
242 TD->getIntPtrType(SrcTy) : 0;
243 Type *MidIntPtrTy = TD && MidTy->isPtrOrPtrVectorTy() ?
244 TD->getIntPtrType(MidTy) : 0;
245 Type *DstIntPtrTy = TD && DstTy->isPtrOrPtrVectorTy() ?
246 TD->getIntPtrType(DstTy) : 0;
247 unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
248 DstTy, SrcIntPtrTy, MidIntPtrTy,
251 // We don't want to form an inttoptr or ptrtoint that converts to an integer
252 // type that differs from the pointer size.
253 if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
254 (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
257 return Instruction::CastOps(Res);
260 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
261 /// results in any code being generated and is interesting to optimize out. If
262 /// the cast can be eliminated by some other simple transformation, we prefer
263 /// to do the simplification first.
264 bool InstCombiner::ShouldOptimizeCast(Instruction::CastOps opc, const Value *V,
266 // Noop casts and casts of constants should be eliminated trivially.
267 if (V->getType() == Ty || isa<Constant>(V)) return false;
269 // If this is another cast that can be eliminated, we prefer to have it
271 if (const CastInst *CI = dyn_cast<CastInst>(V))
272 if (isEliminableCastPair(CI, opc, Ty, TD))
275 // If this is a vector sext from a compare, then we don't want to break the
276 // idiom where each element of the extended vector is either zero or all ones.
277 if (opc == Instruction::SExt && isa<CmpInst>(V) && Ty->isVectorTy())
284 /// @brief Implement the transforms common to all CastInst visitors.
285 Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
286 Value *Src = CI.getOperand(0);
288 // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
290 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
291 if (Instruction::CastOps opc =
292 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
293 // The first cast (CSrc) is eliminable so we need to fix up or replace
294 // the second cast (CI). CSrc will then have a good chance of being dead.
295 return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
299 // If we are casting a select then fold the cast into the select
300 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
301 if (Instruction *NV = FoldOpIntoSelect(CI, SI))
304 // If we are casting a PHI then fold the cast into the PHI
305 if (isa<PHINode>(Src)) {
306 // We don't do this if this would create a PHI node with an illegal type if
307 // it is currently legal.
308 if (!Src->getType()->isIntegerTy() ||
309 !CI.getType()->isIntegerTy() ||
310 ShouldChangeType(CI.getType(), Src->getType()))
311 if (Instruction *NV = FoldOpIntoPhi(CI))
318 /// CanEvaluateTruncated - Return true if we can evaluate the specified
319 /// expression tree as type Ty instead of its larger type, and arrive with the
320 /// same value. This is used by code that tries to eliminate truncates.
322 /// Ty will always be a type smaller than V. We should return true if trunc(V)
323 /// can be computed by computing V in the smaller type. If V is an instruction,
324 /// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
325 /// makes sense if x and y can be efficiently truncated.
327 /// This function works on both vectors and scalars.
329 static bool CanEvaluateTruncated(Value *V, Type *Ty) {
330 // We can always evaluate constants in another type.
331 if (isa<Constant>(V))
334 Instruction *I = dyn_cast<Instruction>(V);
335 if (!I) return false;
337 Type *OrigTy = V->getType();
339 // If this is an extension from the dest type, we can eliminate it, even if it
340 // has multiple uses.
341 if ((isa<ZExtInst>(I) || isa<SExtInst>(I)) &&
342 I->getOperand(0)->getType() == Ty)
345 // We can't extend or shrink something that has multiple uses: doing so would
346 // require duplicating the instruction in general, which isn't profitable.
347 if (!I->hasOneUse()) return false;
349 unsigned Opc = I->getOpcode();
351 case Instruction::Add:
352 case Instruction::Sub:
353 case Instruction::Mul:
354 case Instruction::And:
355 case Instruction::Or:
356 case Instruction::Xor:
357 // These operators can all arbitrarily be extended or truncated.
358 return CanEvaluateTruncated(I->getOperand(0), Ty) &&
359 CanEvaluateTruncated(I->getOperand(1), Ty);
361 case Instruction::UDiv:
362 case Instruction::URem: {
363 // UDiv and URem can be truncated if all the truncated bits are zero.
364 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
365 uint32_t BitWidth = Ty->getScalarSizeInBits();
366 if (BitWidth < OrigBitWidth) {
367 APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
368 if (MaskedValueIsZero(I->getOperand(0), Mask) &&
369 MaskedValueIsZero(I->getOperand(1), Mask)) {
370 return CanEvaluateTruncated(I->getOperand(0), Ty) &&
371 CanEvaluateTruncated(I->getOperand(1), Ty);
376 case Instruction::Shl:
377 // 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.
379 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
380 uint32_t BitWidth = Ty->getScalarSizeInBits();
381 if (CI->getLimitedValue(BitWidth) < BitWidth)
382 return CanEvaluateTruncated(I->getOperand(0), Ty);
385 case Instruction::LShr:
386 // If this is a truncate of a logical shr, we can truncate it to a smaller
387 // lshr iff we know that the bits we would otherwise be shifting in are
389 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
390 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
391 uint32_t BitWidth = Ty->getScalarSizeInBits();
392 if (MaskedValueIsZero(I->getOperand(0),
393 APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
394 CI->getLimitedValue(BitWidth) < BitWidth) {
395 return CanEvaluateTruncated(I->getOperand(0), Ty);
399 case Instruction::Trunc:
400 // trunc(trunc(x)) -> trunc(x)
402 case Instruction::ZExt:
403 case Instruction::SExt:
404 // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
405 // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
407 case Instruction::Select: {
408 SelectInst *SI = cast<SelectInst>(I);
409 return CanEvaluateTruncated(SI->getTrueValue(), Ty) &&
410 CanEvaluateTruncated(SI->getFalseValue(), Ty);
412 case Instruction::PHI: {
413 // We can change a phi if we can change all operands. Note that we never
414 // get into trouble with cyclic PHIs here because we only consider
415 // instructions with a single use.
416 PHINode *PN = cast<PHINode>(I);
417 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
418 if (!CanEvaluateTruncated(PN->getIncomingValue(i), Ty))
423 // TODO: Can handle more cases here.
430 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
431 if (Instruction *Result = commonCastTransforms(CI))
434 // See if we can simplify any instructions used by the input whose sole
435 // purpose is to compute bits we don't care about.
436 if (SimplifyDemandedInstructionBits(CI))
439 Value *Src = CI.getOperand(0);
440 Type *DestTy = CI.getType(), *SrcTy = Src->getType();
442 // Attempt to truncate the entire input expression tree to the destination
443 // type. Only do this if the dest type is a simple type, don't convert the
444 // expression tree to something weird like i93 unless the source is also
446 if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
447 CanEvaluateTruncated(Src, DestTy)) {
449 // If this cast is a truncate, evaluting in a different type always
450 // eliminates the cast, so it is always a win.
451 DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
452 " to avoid cast: " << CI << '\n');
453 Value *Res = EvaluateInDifferentType(Src, DestTy, false);
454 assert(Res->getType() == DestTy);
455 return ReplaceInstUsesWith(CI, Res);
458 // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0), likewise for vector.
459 if (DestTy->getScalarSizeInBits() == 1) {
460 Constant *One = ConstantInt::get(Src->getType(), 1);
461 Src = Builder->CreateAnd(Src, One);
462 Value *Zero = Constant::getNullValue(Src->getType());
463 return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
466 // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
467 Value *A = 0; ConstantInt *Cst = 0;
468 if (Src->hasOneUse() &&
469 match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
470 // We have three types to worry about here, the type of A, the source of
471 // the truncate (MidSize), and the destination of the truncate. We know that
472 // ASize < MidSize and MidSize > ResultSize, but don't know the relation
473 // between ASize and ResultSize.
474 unsigned ASize = A->getType()->getPrimitiveSizeInBits();
476 // If the shift amount is larger than the size of A, then the result is
477 // known to be zero because all the input bits got shifted out.
478 if (Cst->getZExtValue() >= ASize)
479 return ReplaceInstUsesWith(CI, Constant::getNullValue(CI.getType()));
481 // Since we're doing an lshr and a zero extend, and know that the shift
482 // amount is smaller than ASize, it is always safe to do the shift in A's
483 // type, then zero extend or truncate to the result.
484 Value *Shift = Builder->CreateLShr(A, Cst->getZExtValue());
485 Shift->takeName(Src);
486 return CastInst::CreateIntegerCast(Shift, CI.getType(), false);
489 // Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
490 // type isn't non-native.
491 if (Src->hasOneUse() && isa<IntegerType>(Src->getType()) &&
492 ShouldChangeType(Src->getType(), CI.getType()) &&
493 match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
494 Value *NewTrunc = Builder->CreateTrunc(A, CI.getType(), A->getName()+".tr");
495 return BinaryOperator::CreateAnd(NewTrunc,
496 ConstantExpr::getTrunc(Cst, CI.getType()));
502 /// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
503 /// in order to eliminate the icmp.
504 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
506 // If we are just checking for a icmp eq of a single bit and zext'ing it
507 // to an integer, then shift the bit to the appropriate place and then
508 // cast to integer to avoid the comparison.
509 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
510 const APInt &Op1CV = Op1C->getValue();
512 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
513 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
514 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
515 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
516 if (!DoXform) return ICI;
518 Value *In = ICI->getOperand(0);
519 Value *Sh = ConstantInt::get(In->getType(),
520 In->getType()->getScalarSizeInBits()-1);
521 In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
522 if (In->getType() != CI.getType())
523 In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/);
525 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
526 Constant *One = ConstantInt::get(In->getType(), 1);
527 In = Builder->CreateXor(In, One, In->getName()+".not");
530 return ReplaceInstUsesWith(CI, In);
533 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
534 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
535 // zext (X == 1) to i32 --> X iff X has only the low bit set.
536 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
537 // zext (X != 0) to i32 --> X iff X has only the low bit set.
538 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
539 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
540 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
541 if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
542 // This only works for EQ and NE
544 // If Op1C some other power of two, convert:
545 uint32_t BitWidth = Op1C->getType()->getBitWidth();
546 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
547 ComputeMaskedBits(ICI->getOperand(0), KnownZero, KnownOne);
549 APInt KnownZeroMask(~KnownZero);
550 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
551 if (!DoXform) return ICI;
553 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
554 if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
555 // (X&4) == 2 --> false
556 // (X&4) != 2 --> true
557 Constant *Res = ConstantInt::get(Type::getInt1Ty(CI.getContext()),
559 Res = ConstantExpr::getZExt(Res, CI.getType());
560 return ReplaceInstUsesWith(CI, Res);
563 uint32_t ShiftAmt = KnownZeroMask.logBase2();
564 Value *In = ICI->getOperand(0);
566 // Perform a logical shr by shiftamt.
567 // Insert the shift to put the result in the low bit.
568 In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
569 In->getName()+".lobit");
572 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
573 Constant *One = ConstantInt::get(In->getType(), 1);
574 In = Builder->CreateXor(In, One);
577 if (CI.getType() == In->getType())
578 return ReplaceInstUsesWith(CI, In);
579 return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
584 // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
585 // It is also profitable to transform icmp eq into not(xor(A, B)) because that
586 // may lead to additional simplifications.
587 if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
588 if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
589 uint32_t BitWidth = ITy->getBitWidth();
590 Value *LHS = ICI->getOperand(0);
591 Value *RHS = ICI->getOperand(1);
593 APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
594 APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
595 ComputeMaskedBits(LHS, KnownZeroLHS, KnownOneLHS);
596 ComputeMaskedBits(RHS, KnownZeroRHS, KnownOneRHS);
598 if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) {
599 APInt KnownBits = KnownZeroLHS | KnownOneLHS;
600 APInt UnknownBit = ~KnownBits;
601 if (UnknownBit.countPopulation() == 1) {
602 if (!DoXform) return ICI;
604 Value *Result = Builder->CreateXor(LHS, RHS);
606 // Mask off any bits that are set and won't be shifted away.
607 if (KnownOneLHS.uge(UnknownBit))
608 Result = Builder->CreateAnd(Result,
609 ConstantInt::get(ITy, UnknownBit));
611 // Shift the bit we're testing down to the lsb.
612 Result = Builder->CreateLShr(
613 Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
615 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
616 Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1));
617 Result->takeName(ICI);
618 return ReplaceInstUsesWith(CI, Result);
627 /// CanEvaluateZExtd - Determine if the specified value can be computed in the
628 /// specified wider type and produce the same low bits. If not, return false.
630 /// If this function returns true, it can also return a non-zero number of bits
631 /// (in BitsToClear) which indicates that the value it computes is correct for
632 /// the zero extend, but that the additional BitsToClear bits need to be zero'd
633 /// out. For example, to promote something like:
635 /// %B = trunc i64 %A to i32
636 /// %C = lshr i32 %B, 8
637 /// %E = zext i32 %C to i64
639 /// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
640 /// set to 8 to indicate that the promoted value needs to have bits 24-31
641 /// cleared in addition to bits 32-63. Since an 'and' will be generated to
642 /// clear the top bits anyway, doing this has no extra cost.
644 /// This function works on both vectors and scalars.
645 static bool CanEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear) {
647 if (isa<Constant>(V))
650 Instruction *I = dyn_cast<Instruction>(V);
651 if (!I) return false;
653 // If the input is a truncate from the destination type, we can trivially
655 if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
658 // We can't extend or shrink something that has multiple uses: doing so would
659 // require duplicating the instruction in general, which isn't profitable.
660 if (!I->hasOneUse()) return false;
662 unsigned Opc = I->getOpcode(), Tmp;
664 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
665 case Instruction::SExt: // zext(sext(x)) -> sext(x).
666 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
668 case Instruction::And:
669 case Instruction::Or:
670 case Instruction::Xor:
671 case Instruction::Add:
672 case Instruction::Sub:
673 case Instruction::Mul:
674 case Instruction::Shl:
675 if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear) ||
676 !CanEvaluateZExtd(I->getOperand(1), Ty, Tmp))
678 // These can all be promoted if neither operand has 'bits to clear'.
679 if (BitsToClear == 0 && Tmp == 0)
682 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
683 // other side, BitsToClear is ok.
685 (Opc == Instruction::And || Opc == Instruction::Or ||
686 Opc == Instruction::Xor)) {
687 // We use MaskedValueIsZero here for generality, but the case we care
688 // about the most is constant RHS.
689 unsigned VSize = V->getType()->getScalarSizeInBits();
690 if (MaskedValueIsZero(I->getOperand(1),
691 APInt::getHighBitsSet(VSize, BitsToClear)))
695 // Otherwise, we don't know how to analyze this BitsToClear case yet.
698 case Instruction::LShr:
699 // We can promote lshr(x, cst) if we can promote x. This requires the
700 // ultimate 'and' to clear out the high zero bits we're clearing out though.
701 if (ConstantInt *Amt = dyn_cast<ConstantInt>(I->getOperand(1))) {
702 if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear))
704 BitsToClear += Amt->getZExtValue();
705 if (BitsToClear > V->getType()->getScalarSizeInBits())
706 BitsToClear = V->getType()->getScalarSizeInBits();
709 // Cannot promote variable LSHR.
711 case Instruction::Select:
712 if (!CanEvaluateZExtd(I->getOperand(1), Ty, Tmp) ||
713 !CanEvaluateZExtd(I->getOperand(2), Ty, BitsToClear) ||
714 // TODO: If important, we could handle the case when the BitsToClear are
715 // known zero in the disagreeing side.
720 case Instruction::PHI: {
721 // We can change a phi if we can change all operands. Note that we never
722 // get into trouble with cyclic PHIs here because we only consider
723 // instructions with a single use.
724 PHINode *PN = cast<PHINode>(I);
725 if (!CanEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear))
727 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
728 if (!CanEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp) ||
729 // TODO: If important, we could handle the case when the BitsToClear
730 // are known zero in the disagreeing input.
736 // TODO: Can handle more cases here.
741 Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
742 // If this zero extend is only used by a truncate, let the truncate be
743 // eliminated before we try to optimize this zext.
744 if (CI.hasOneUse() && isa<TruncInst>(CI.use_back()))
747 // If one of the common conversion will work, do it.
748 if (Instruction *Result = commonCastTransforms(CI))
751 // See if we can simplify any instructions used by the input whose sole
752 // purpose is to compute bits we don't care about.
753 if (SimplifyDemandedInstructionBits(CI))
756 Value *Src = CI.getOperand(0);
757 Type *SrcTy = Src->getType(), *DestTy = CI.getType();
759 // Attempt to extend the entire input expression tree to the destination
760 // type. Only do this if the dest type is a simple type, don't convert the
761 // expression tree to something weird like i93 unless the source is also
763 unsigned BitsToClear;
764 if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
765 CanEvaluateZExtd(Src, DestTy, BitsToClear)) {
766 assert(BitsToClear < SrcTy->getScalarSizeInBits() &&
767 "Unreasonable BitsToClear");
769 // Okay, we can transform this! Insert the new expression now.
770 DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
771 " to avoid zero extend: " << CI);
772 Value *Res = EvaluateInDifferentType(Src, DestTy, false);
773 assert(Res->getType() == DestTy);
775 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
776 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
778 // If the high bits are already filled with zeros, just replace this
779 // cast with the result.
780 if (MaskedValueIsZero(Res, APInt::getHighBitsSet(DestBitSize,
781 DestBitSize-SrcBitsKept)))
782 return ReplaceInstUsesWith(CI, Res);
784 // We need to emit an AND to clear the high bits.
785 Constant *C = ConstantInt::get(Res->getType(),
786 APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
787 return BinaryOperator::CreateAnd(Res, C);
790 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
791 // types and if the sizes are just right we can convert this into a logical
792 // 'and' which will be much cheaper than the pair of casts.
793 if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
794 // TODO: Subsume this into EvaluateInDifferentType.
796 // Get the sizes of the types involved. We know that the intermediate type
797 // will be smaller than A or C, but don't know the relation between A and C.
798 Value *A = CSrc->getOperand(0);
799 unsigned SrcSize = A->getType()->getScalarSizeInBits();
800 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
801 unsigned DstSize = CI.getType()->getScalarSizeInBits();
802 // If we're actually extending zero bits, then if
803 // SrcSize < DstSize: zext(a & mask)
804 // SrcSize == DstSize: a & mask
805 // SrcSize > DstSize: trunc(a) & mask
806 if (SrcSize < DstSize) {
807 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
808 Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
809 Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
810 return new ZExtInst(And, CI.getType());
813 if (SrcSize == DstSize) {
814 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
815 return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
818 if (SrcSize > DstSize) {
819 Value *Trunc = Builder->CreateTrunc(A, CI.getType());
820 APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
821 return BinaryOperator::CreateAnd(Trunc,
822 ConstantInt::get(Trunc->getType(),
827 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
828 return transformZExtICmp(ICI, CI);
830 BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
831 if (SrcI && SrcI->getOpcode() == Instruction::Or) {
832 // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
833 // of the (zext icmp) will be transformed.
834 ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
835 ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
836 if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
837 (transformZExtICmp(LHS, CI, false) ||
838 transformZExtICmp(RHS, CI, false))) {
839 Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
840 Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
841 return BinaryOperator::Create(Instruction::Or, LCast, RCast);
845 // zext(trunc(t) & C) -> (t & zext(C)).
846 if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
847 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
848 if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
849 Value *TI0 = TI->getOperand(0);
850 if (TI0->getType() == CI.getType())
852 BinaryOperator::CreateAnd(TI0,
853 ConstantExpr::getZExt(C, CI.getType()));
856 // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
857 if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
858 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
859 if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
860 if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
861 And->getOperand(1) == C)
862 if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
863 Value *TI0 = TI->getOperand(0);
864 if (TI0->getType() == CI.getType()) {
865 Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
866 Value *NewAnd = Builder->CreateAnd(TI0, ZC);
867 return BinaryOperator::CreateXor(NewAnd, ZC);
871 // zext (xor i1 X, true) to i32 --> xor (zext i1 X to i32), 1
873 if (SrcI && SrcI->hasOneUse() && SrcI->getType()->isIntegerTy(1) &&
874 match(SrcI, m_Not(m_Value(X))) &&
875 (!X->hasOneUse() || !isa<CmpInst>(X))) {
876 Value *New = Builder->CreateZExt(X, CI.getType());
877 return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1));
883 /// transformSExtICmp - Transform (sext icmp) to bitwise / integer operations
884 /// in order to eliminate the icmp.
885 Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) {
886 Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
887 ICmpInst::Predicate Pred = ICI->getPredicate();
889 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
890 // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative
891 // (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive
892 if ((Pred == ICmpInst::ICMP_SLT && Op1C->isZero()) ||
893 (Pred == ICmpInst::ICMP_SGT && Op1C->isAllOnesValue())) {
895 Value *Sh = ConstantInt::get(Op0->getType(),
896 Op0->getType()->getScalarSizeInBits()-1);
897 Value *In = Builder->CreateAShr(Op0, Sh, Op0->getName()+".lobit");
898 if (In->getType() != CI.getType())
899 In = Builder->CreateIntCast(In, CI.getType(), true/*SExt*/);
901 if (Pred == ICmpInst::ICMP_SGT)
902 In = Builder->CreateNot(In, In->getName()+".not");
903 return ReplaceInstUsesWith(CI, In);
906 // If we know that only one bit of the LHS of the icmp can be set and we
907 // have an equality comparison with zero or a power of 2, we can transform
908 // the icmp and sext into bitwise/integer operations.
909 if (ICI->hasOneUse() &&
910 ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){
911 unsigned BitWidth = Op1C->getType()->getBitWidth();
912 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
913 ComputeMaskedBits(Op0, KnownZero, KnownOne);
915 APInt KnownZeroMask(~KnownZero);
916 if (KnownZeroMask.isPowerOf2()) {
917 Value *In = ICI->getOperand(0);
919 // If the icmp tests for a known zero bit we can constant fold it.
920 if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) {
921 Value *V = Pred == ICmpInst::ICMP_NE ?
922 ConstantInt::getAllOnesValue(CI.getType()) :
923 ConstantInt::getNullValue(CI.getType());
924 return ReplaceInstUsesWith(CI, V);
927 if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) {
928 // sext ((x & 2^n) == 0) -> (x >> n) - 1
929 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1
930 unsigned ShiftAmt = KnownZeroMask.countTrailingZeros();
931 // Perform a right shift to place the desired bit in the LSB.
933 In = Builder->CreateLShr(In,
934 ConstantInt::get(In->getType(), ShiftAmt));
936 // At this point "In" is either 1 or 0. Subtract 1 to turn
937 // {1, 0} -> {0, -1}.
938 In = Builder->CreateAdd(In,
939 ConstantInt::getAllOnesValue(In->getType()),
942 // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1
943 // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1
944 unsigned ShiftAmt = KnownZeroMask.countLeadingZeros();
945 // Perform a left shift to place the desired bit in the MSB.
947 In = Builder->CreateShl(In,
948 ConstantInt::get(In->getType(), ShiftAmt));
950 // Distribute the bit over the whole bit width.
951 In = Builder->CreateAShr(In, ConstantInt::get(In->getType(),
952 BitWidth - 1), "sext");
955 if (CI.getType() == In->getType())
956 return ReplaceInstUsesWith(CI, In);
957 return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/);
962 // vector (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed.
963 if (VectorType *VTy = dyn_cast<VectorType>(CI.getType())) {
964 if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_Zero()) &&
965 Op0->getType() == CI.getType()) {
966 Type *EltTy = VTy->getElementType();
968 // splat the shift constant to a constant vector.
969 Constant *VSh = ConstantInt::get(VTy, EltTy->getScalarSizeInBits()-1);
970 Value *In = Builder->CreateAShr(Op0, VSh, Op0->getName()+".lobit");
971 return ReplaceInstUsesWith(CI, In);
978 /// CanEvaluateSExtd - Return true if we can take the specified value
979 /// and return it as type Ty without inserting any new casts and without
980 /// changing the value of the common low bits. This is used by code that tries
981 /// to promote integer operations to a wider types will allow us to eliminate
984 /// This function works on both vectors and scalars.
986 static bool CanEvaluateSExtd(Value *V, Type *Ty) {
987 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
988 "Can't sign extend type to a smaller type");
989 // If this is a constant, it can be trivially promoted.
990 if (isa<Constant>(V))
993 Instruction *I = dyn_cast<Instruction>(V);
994 if (!I) return false;
996 // If this is a truncate from the dest type, we can trivially eliminate it.
997 if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
1000 // We can't extend or shrink something that has multiple uses: doing so would
1001 // require duplicating the instruction in general, which isn't profitable.
1002 if (!I->hasOneUse()) return false;
1004 switch (I->getOpcode()) {
1005 case Instruction::SExt: // sext(sext(x)) -> sext(x)
1006 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
1007 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
1009 case Instruction::And:
1010 case Instruction::Or:
1011 case Instruction::Xor:
1012 case Instruction::Add:
1013 case Instruction::Sub:
1014 case Instruction::Mul:
1015 // These operators can all arbitrarily be extended if their inputs can.
1016 return CanEvaluateSExtd(I->getOperand(0), Ty) &&
1017 CanEvaluateSExtd(I->getOperand(1), Ty);
1019 //case Instruction::Shl: TODO
1020 //case Instruction::LShr: TODO
1022 case Instruction::Select:
1023 return CanEvaluateSExtd(I->getOperand(1), Ty) &&
1024 CanEvaluateSExtd(I->getOperand(2), Ty);
1026 case Instruction::PHI: {
1027 // We can change a phi if we can change all operands. Note that we never
1028 // get into trouble with cyclic PHIs here because we only consider
1029 // instructions with a single use.
1030 PHINode *PN = cast<PHINode>(I);
1031 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
1032 if (!CanEvaluateSExtd(PN->getIncomingValue(i), Ty)) return false;
1036 // TODO: Can handle more cases here.
1043 Instruction *InstCombiner::visitSExt(SExtInst &CI) {
1044 // If this sign extend is only used by a truncate, let the truncate by
1045 // eliminated before we try to optimize this zext.
1046 if (CI.hasOneUse() && isa<TruncInst>(CI.use_back()))
1049 if (Instruction *I = commonCastTransforms(CI))
1052 // See if we can simplify any instructions used by the input whose sole
1053 // purpose is to compute bits we don't care about.
1054 if (SimplifyDemandedInstructionBits(CI))
1057 Value *Src = CI.getOperand(0);
1058 Type *SrcTy = Src->getType(), *DestTy = CI.getType();
1060 // Attempt to extend the entire input expression tree to the destination
1061 // type. Only do this if the dest type is a simple type, don't convert the
1062 // expression tree to something weird like i93 unless the source is also
1064 if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
1065 CanEvaluateSExtd(Src, DestTy)) {
1066 // Okay, we can transform this! Insert the new expression now.
1067 DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
1068 " to avoid sign extend: " << CI);
1069 Value *Res = EvaluateInDifferentType(Src, DestTy, true);
1070 assert(Res->getType() == DestTy);
1072 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
1073 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1075 // If the high bits are already filled with sign bit, just replace this
1076 // cast with the result.
1077 if (ComputeNumSignBits(Res) > DestBitSize - SrcBitSize)
1078 return ReplaceInstUsesWith(CI, Res);
1080 // We need to emit a shl + ashr to do the sign extend.
1081 Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
1082 return BinaryOperator::CreateAShr(Builder->CreateShl(Res, ShAmt, "sext"),
1086 // If this input is a trunc from our destination, then turn sext(trunc(x))
1088 if (TruncInst *TI = dyn_cast<TruncInst>(Src))
1089 if (TI->hasOneUse() && TI->getOperand(0)->getType() == DestTy) {
1090 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
1091 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
1093 // We need to emit a shl + ashr to do the sign extend.
1094 Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
1095 Value *Res = Builder->CreateShl(TI->getOperand(0), ShAmt, "sext");
1096 return BinaryOperator::CreateAShr(Res, ShAmt);
1099 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
1100 return transformSExtICmp(ICI, CI);
1102 // If the input is a shl/ashr pair of a same constant, then this is a sign
1103 // extension from a smaller value. If we could trust arbitrary bitwidth
1104 // integers, we could turn this into a truncate to the smaller bit and then
1105 // use a sext for the whole extension. Since we don't, look deeper and check
1106 // for a truncate. If the source and dest are the same type, eliminate the
1107 // trunc and extend and just do shifts. For example, turn:
1108 // %a = trunc i32 %i to i8
1109 // %b = shl i8 %a, 6
1110 // %c = ashr i8 %b, 6
1111 // %d = sext i8 %c to i32
1113 // %a = shl i32 %i, 30
1114 // %d = ashr i32 %a, 30
1116 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1117 ConstantInt *BA = 0, *CA = 0;
1118 if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
1119 m_ConstantInt(CA))) &&
1120 BA == CA && A->getType() == CI.getType()) {
1121 unsigned MidSize = Src->getType()->getScalarSizeInBits();
1122 unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
1123 unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
1124 Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
1125 A = Builder->CreateShl(A, ShAmtV, CI.getName());
1126 return BinaryOperator::CreateAShr(A, ShAmtV);
1133 /// FitsInFPType - Return a Constant* for the specified FP constant if it fits
1134 /// in the specified FP type without changing its value.
1135 static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
1137 APFloat F = CFP->getValueAPF();
1138 (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
1140 return ConstantFP::get(CFP->getContext(), F);
1144 /// LookThroughFPExtensions - If this is an fp extension instruction, look
1145 /// through it until we get the source value.
1146 static Value *LookThroughFPExtensions(Value *V) {
1147 if (Instruction *I = dyn_cast<Instruction>(V))
1148 if (I->getOpcode() == Instruction::FPExt)
1149 return LookThroughFPExtensions(I->getOperand(0));
1151 // If this value is a constant, return the constant in the smallest FP type
1152 // that can accurately represent it. This allows us to turn
1153 // (float)((double)X+2.0) into x+2.0f.
1154 if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
1155 if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext()))
1156 return V; // No constant folding of this.
1157 // See if the value can be truncated to half and then reextended.
1158 if (Value *V = FitsInFPType(CFP, APFloat::IEEEhalf))
1160 // See if the value can be truncated to float and then reextended.
1161 if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
1163 if (CFP->getType()->isDoubleTy())
1164 return V; // Won't shrink.
1165 if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble))
1167 // Don't try to shrink to various long double types.
1173 Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
1174 if (Instruction *I = commonCastTransforms(CI))
1177 // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are
1178 // smaller than the destination type, we can eliminate the truncate by doing
1179 // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well
1180 // as many builtins (sqrt, etc).
1181 BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
1182 if (OpI && OpI->hasOneUse()) {
1183 switch (OpI->getOpcode()) {
1185 case Instruction::FAdd:
1186 case Instruction::FSub:
1187 case Instruction::FMul:
1188 case Instruction::FDiv:
1189 case Instruction::FRem:
1190 Type *SrcTy = OpI->getType();
1191 Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0));
1192 Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1));
1193 if (LHSTrunc->getType() != SrcTy &&
1194 RHSTrunc->getType() != SrcTy) {
1195 unsigned DstSize = CI.getType()->getScalarSizeInBits();
1196 // If the source types were both smaller than the destination type of
1197 // the cast, do this xform.
1198 if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize &&
1199 RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) {
1200 LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType());
1201 RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType());
1202 return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
1208 // (fptrunc (fneg x)) -> (fneg (fptrunc x))
1209 if (BinaryOperator::isFNeg(OpI)) {
1210 Value *InnerTrunc = Builder->CreateFPTrunc(OpI->getOperand(1),
1212 return BinaryOperator::CreateFNeg(InnerTrunc);
1216 IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI.getOperand(0));
1218 switch (II->getIntrinsicID()) {
1220 case Intrinsic::fabs: {
1221 // (fptrunc (fabs x)) -> (fabs (fptrunc x))
1222 Value *InnerTrunc = Builder->CreateFPTrunc(II->getArgOperand(0),
1224 Type *IntrinsicType[] = { CI.getType() };
1225 Function *Overload =
1226 Intrinsic::getDeclaration(CI.getParent()->getParent()->getParent(),
1227 II->getIntrinsicID(), IntrinsicType);
1229 Value *Args[] = { InnerTrunc };
1230 return CallInst::Create(Overload, Args, II->getName());
1235 // Fold (fptrunc (sqrt (fpext x))) -> (sqrtf x)
1236 CallInst *Call = dyn_cast<CallInst>(CI.getOperand(0));
1237 if (Call && Call->getCalledFunction() && TLI->has(LibFunc::sqrtf) &&
1238 Call->getCalledFunction()->getName() == TLI->getName(LibFunc::sqrt) &&
1239 Call->getNumArgOperands() == 1 &&
1240 Call->hasOneUse()) {
1241 CastInst *Arg = dyn_cast<CastInst>(Call->getArgOperand(0));
1242 if (Arg && Arg->getOpcode() == Instruction::FPExt &&
1243 CI.getType()->isFloatTy() &&
1244 Call->getType()->isDoubleTy() &&
1245 Arg->getType()->isDoubleTy() &&
1246 Arg->getOperand(0)->getType()->isFloatTy()) {
1247 Function *Callee = Call->getCalledFunction();
1248 Module *M = CI.getParent()->getParent()->getParent();
1249 Constant *SqrtfFunc = M->getOrInsertFunction("sqrtf",
1250 Callee->getAttributes(),
1251 Builder->getFloatTy(),
1252 Builder->getFloatTy(),
1254 CallInst *ret = CallInst::Create(SqrtfFunc, Arg->getOperand(0),
1256 ret->setAttributes(Callee->getAttributes());
1259 // Remove the old Call. With -fmath-errno, it won't get marked readnone.
1260 ReplaceInstUsesWith(*Call, UndefValue::get(Call->getType()));
1261 EraseInstFromFunction(*Call);
1269 Instruction *InstCombiner::visitFPExt(CastInst &CI) {
1270 return commonCastTransforms(CI);
1273 Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
1274 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1276 return commonCastTransforms(FI);
1278 // fptoui(uitofp(X)) --> X
1279 // fptoui(sitofp(X)) --> X
1280 // This is safe if the intermediate type has enough bits in its mantissa to
1281 // accurately represent all values of X. For example, do not do this with
1282 // i64->float->i64. This is also safe for sitofp case, because any negative
1283 // 'X' value would cause an undefined result for the fptoui.
1284 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
1285 OpI->getOperand(0)->getType() == FI.getType() &&
1286 (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
1287 OpI->getType()->getFPMantissaWidth())
1288 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
1290 return commonCastTransforms(FI);
1293 Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
1294 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1296 return commonCastTransforms(FI);
1298 // fptosi(sitofp(X)) --> X
1299 // fptosi(uitofp(X)) --> X
1300 // This is safe if the intermediate type has enough bits in its mantissa to
1301 // accurately represent all values of X. For example, do not do this with
1302 // i64->float->i64. This is also safe for sitofp case, because any negative
1303 // 'X' value would cause an undefined result for the fptoui.
1304 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
1305 OpI->getOperand(0)->getType() == FI.getType() &&
1306 (int)FI.getType()->getScalarSizeInBits() <=
1307 OpI->getType()->getFPMantissaWidth())
1308 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
1310 return commonCastTransforms(FI);
1313 Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
1314 return commonCastTransforms(CI);
1317 Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
1318 return commonCastTransforms(CI);
1321 Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
1322 // If the source integer type is not the intptr_t type for this target, do a
1323 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
1324 // cast to be exposed to other transforms.
1326 if (CI.getOperand(0)->getType()->getScalarSizeInBits() >
1327 TD->getPointerSizeInBits()) {
1328 Value *P = Builder->CreateTrunc(CI.getOperand(0),
1329 TD->getIntPtrType(CI.getContext()));
1330 return new IntToPtrInst(P, CI.getType());
1332 if (CI.getOperand(0)->getType()->getScalarSizeInBits() <
1333 TD->getPointerSizeInBits()) {
1334 Value *P = Builder->CreateZExt(CI.getOperand(0),
1335 TD->getIntPtrType(CI.getContext()));
1336 return new IntToPtrInst(P, CI.getType());
1340 if (Instruction *I = commonCastTransforms(CI))
1346 /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
1347 Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
1348 Value *Src = CI.getOperand(0);
1350 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
1351 // If casting the result of a getelementptr instruction with no offset, turn
1352 // this into a cast of the original pointer!
1353 if (GEP->hasAllZeroIndices()) {
1354 // Changing the cast operand is usually not a good idea but it is safe
1355 // here because the pointer operand is being replaced with another
1356 // pointer operand so the opcode doesn't need to change.
1358 CI.setOperand(0, GEP->getOperand(0));
1362 // If the GEP has a single use, and the base pointer is a bitcast, and the
1363 // GEP computes a constant offset, see if we can convert these three
1364 // instructions into fewer. This typically happens with unions and other
1365 // non-type-safe code.
1366 APInt Offset(TD ? TD->getPointerSizeInBits() : 1, 0);
1367 if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0)) &&
1368 GEP->accumulateConstantOffset(*TD, Offset)) {
1369 // Get the base pointer input of the bitcast, and the type it points to.
1370 Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
1372 cast<PointerType>(OrigBase->getType())->getElementType();
1373 SmallVector<Value*, 8> NewIndices;
1374 if (FindElementAtOffset(GEPIdxTy, Offset.getSExtValue(), NewIndices)) {
1375 // If we were able to index down into an element, create the GEP
1376 // and bitcast the result. This eliminates one bitcast, potentially
1378 Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
1379 Builder->CreateInBoundsGEP(OrigBase, NewIndices) :
1380 Builder->CreateGEP(OrigBase, NewIndices);
1381 NGEP->takeName(GEP);
1383 if (isa<BitCastInst>(CI))
1384 return new BitCastInst(NGEP, CI.getType());
1385 assert(isa<PtrToIntInst>(CI));
1386 return new PtrToIntInst(NGEP, CI.getType());
1391 return commonCastTransforms(CI);
1394 Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
1395 // If the destination integer type is not the intptr_t type for this target,
1396 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
1397 // to be exposed to other transforms.
1398 if (TD && CI.getType()->getScalarSizeInBits() != TD->getPointerSizeInBits()) {
1399 Type *Ty = TD->getIntPtrType(CI.getContext());
1400 if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
1401 Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements());
1403 Value *P = Builder->CreatePtrToInt(CI.getOperand(0), Ty);
1404 return CastInst::CreateIntegerCast(P, CI.getType(), /*isSigned=*/false);
1407 return commonPointerCastTransforms(CI);
1410 /// OptimizeVectorResize - This input value (which is known to have vector type)
1411 /// is being zero extended or truncated to the specified vector type. Try to
1412 /// replace it with a shuffle (and vector/vector bitcast) if possible.
1414 /// The source and destination vector types may have different element types.
1415 static Instruction *OptimizeVectorResize(Value *InVal, VectorType *DestTy,
1417 // We can only do this optimization if the output is a multiple of the input
1418 // element size, or the input is a multiple of the output element size.
1419 // Convert the input type to have the same element type as the output.
1420 VectorType *SrcTy = cast<VectorType>(InVal->getType());
1422 if (SrcTy->getElementType() != DestTy->getElementType()) {
1423 // The input types don't need to be identical, but for now they must be the
1424 // same size. There is no specific reason we couldn't handle things like
1425 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
1427 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
1428 DestTy->getElementType()->getPrimitiveSizeInBits())
1431 SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
1432 InVal = IC.Builder->CreateBitCast(InVal, SrcTy);
1435 // Now that the element types match, get the shuffle mask and RHS of the
1436 // shuffle to use, which depends on whether we're increasing or decreasing the
1437 // size of the input.
1438 SmallVector<uint32_t, 16> ShuffleMask;
1441 if (SrcTy->getNumElements() > DestTy->getNumElements()) {
1442 // If we're shrinking the number of elements, just shuffle in the low
1443 // elements from the input and use undef as the second shuffle input.
1444 V2 = UndefValue::get(SrcTy);
1445 for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
1446 ShuffleMask.push_back(i);
1449 // If we're increasing the number of elements, shuffle in all of the
1450 // elements from InVal and fill the rest of the result elements with zeros
1451 // from a constant zero.
1452 V2 = Constant::getNullValue(SrcTy);
1453 unsigned SrcElts = SrcTy->getNumElements();
1454 for (unsigned i = 0, e = SrcElts; i != e; ++i)
1455 ShuffleMask.push_back(i);
1457 // The excess elements reference the first element of the zero input.
1458 for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i)
1459 ShuffleMask.push_back(SrcElts);
1462 return new ShuffleVectorInst(InVal, V2,
1463 ConstantDataVector::get(V2->getContext(),
1467 static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) {
1468 return Value % Ty->getPrimitiveSizeInBits() == 0;
1471 static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) {
1472 return Value / Ty->getPrimitiveSizeInBits();
1475 /// CollectInsertionElements - V is a value which is inserted into a vector of
1476 /// VecEltTy. Look through the value to see if we can decompose it into
1477 /// insertions into the vector. See the example in the comment for
1478 /// OptimizeIntegerToVectorInsertions for the pattern this handles.
1479 /// The type of V is always a non-zero multiple of VecEltTy's size.
1481 /// This returns false if the pattern can't be matched or true if it can,
1482 /// filling in Elements with the elements found here.
1483 static bool CollectInsertionElements(Value *V, unsigned ElementIndex,
1484 SmallVectorImpl<Value*> &Elements,
1486 // Undef values never contribute useful bits to the result.
1487 if (isa<UndefValue>(V)) return true;
1489 // If we got down to a value of the right type, we win, try inserting into the
1491 if (V->getType() == VecEltTy) {
1492 // Inserting null doesn't actually insert any elements.
1493 if (Constant *C = dyn_cast<Constant>(V))
1494 if (C->isNullValue())
1497 // Fail if multiple elements are inserted into this slot.
1498 if (ElementIndex >= Elements.size() || Elements[ElementIndex] != 0)
1501 Elements[ElementIndex] = V;
1505 if (Constant *C = dyn_cast<Constant>(V)) {
1506 // Figure out the # elements this provides, and bitcast it or slice it up
1508 unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
1510 // If the constant is the size of a vector element, we just need to bitcast
1511 // it to the right type so it gets properly inserted.
1513 return CollectInsertionElements(ConstantExpr::getBitCast(C, VecEltTy),
1514 ElementIndex, Elements, VecEltTy);
1516 // Okay, this is a constant that covers multiple elements. Slice it up into
1517 // pieces and insert each element-sized piece into the vector.
1518 if (!isa<IntegerType>(C->getType()))
1519 C = ConstantExpr::getBitCast(C, IntegerType::get(V->getContext(),
1520 C->getType()->getPrimitiveSizeInBits()));
1521 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
1522 Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
1524 for (unsigned i = 0; i != NumElts; ++i) {
1525 Constant *Piece = ConstantExpr::getLShr(C, ConstantInt::get(C->getType(),
1527 Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
1528 if (!CollectInsertionElements(Piece, ElementIndex+i, Elements, VecEltTy))
1534 if (!V->hasOneUse()) return false;
1536 Instruction *I = dyn_cast<Instruction>(V);
1537 if (I == 0) return false;
1538 switch (I->getOpcode()) {
1539 default: return false; // Unhandled case.
1540 case Instruction::BitCast:
1541 return CollectInsertionElements(I->getOperand(0), ElementIndex,
1542 Elements, VecEltTy);
1543 case Instruction::ZExt:
1544 if (!isMultipleOfTypeSize(
1545 I->getOperand(0)->getType()->getPrimitiveSizeInBits(),
1548 return CollectInsertionElements(I->getOperand(0), ElementIndex,
1549 Elements, VecEltTy);
1550 case Instruction::Or:
1551 return CollectInsertionElements(I->getOperand(0), ElementIndex,
1552 Elements, VecEltTy) &&
1553 CollectInsertionElements(I->getOperand(1), ElementIndex,
1554 Elements, VecEltTy);
1555 case Instruction::Shl: {
1556 // Must be shifting by a constant that is a multiple of the element size.
1557 ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1));
1558 if (CI == 0) return false;
1559 if (!isMultipleOfTypeSize(CI->getZExtValue(), VecEltTy)) return false;
1560 unsigned IndexShift = getTypeSizeIndex(CI->getZExtValue(), VecEltTy);
1562 return CollectInsertionElements(I->getOperand(0), ElementIndex+IndexShift,
1563 Elements, VecEltTy);
1570 /// OptimizeIntegerToVectorInsertions - If the input is an 'or' instruction, we
1571 /// may be doing shifts and ors to assemble the elements of the vector manually.
1572 /// Try to rip the code out and replace it with insertelements. This is to
1573 /// optimize code like this:
1575 /// %tmp37 = bitcast float %inc to i32
1576 /// %tmp38 = zext i32 %tmp37 to i64
1577 /// %tmp31 = bitcast float %inc5 to i32
1578 /// %tmp32 = zext i32 %tmp31 to i64
1579 /// %tmp33 = shl i64 %tmp32, 32
1580 /// %ins35 = or i64 %tmp33, %tmp38
1581 /// %tmp43 = bitcast i64 %ins35 to <2 x float>
1583 /// Into two insertelements that do "buildvector{%inc, %inc5}".
1584 static Value *OptimizeIntegerToVectorInsertions(BitCastInst &CI,
1586 VectorType *DestVecTy = cast<VectorType>(CI.getType());
1587 Value *IntInput = CI.getOperand(0);
1589 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
1590 if (!CollectInsertionElements(IntInput, 0, Elements,
1591 DestVecTy->getElementType()))
1594 // If we succeeded, we know that all of the element are specified by Elements
1595 // or are zero if Elements has a null entry. Recast this as a set of
1597 Value *Result = Constant::getNullValue(CI.getType());
1598 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
1599 if (Elements[i] == 0) continue; // Unset element.
1601 Result = IC.Builder->CreateInsertElement(Result, Elements[i],
1602 IC.Builder->getInt32(i));
1609 /// OptimizeIntToFloatBitCast - See if we can optimize an integer->float/double
1610 /// bitcast. The various long double bitcasts can't get in here.
1611 static Instruction *OptimizeIntToFloatBitCast(BitCastInst &CI,InstCombiner &IC){
1612 Value *Src = CI.getOperand(0);
1613 Type *DestTy = CI.getType();
1615 // If this is a bitcast from int to float, check to see if the int is an
1616 // extraction from a vector.
1617 Value *VecInput = 0;
1618 // bitcast(trunc(bitcast(somevector)))
1619 if (match(Src, m_Trunc(m_BitCast(m_Value(VecInput)))) &&
1620 isa<VectorType>(VecInput->getType())) {
1621 VectorType *VecTy = cast<VectorType>(VecInput->getType());
1622 unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
1624 if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0) {
1625 // If the element type of the vector doesn't match the result type,
1626 // bitcast it to be a vector type we can extract from.
1627 if (VecTy->getElementType() != DestTy) {
1628 VecTy = VectorType::get(DestTy,
1629 VecTy->getPrimitiveSizeInBits() / DestWidth);
1630 VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
1633 return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(0));
1637 // bitcast(trunc(lshr(bitcast(somevector), cst))
1638 ConstantInt *ShAmt = 0;
1639 if (match(Src, m_Trunc(m_LShr(m_BitCast(m_Value(VecInput)),
1640 m_ConstantInt(ShAmt)))) &&
1641 isa<VectorType>(VecInput->getType())) {
1642 VectorType *VecTy = cast<VectorType>(VecInput->getType());
1643 unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
1644 if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0 &&
1645 ShAmt->getZExtValue() % DestWidth == 0) {
1646 // If the element type of the vector doesn't match the result type,
1647 // bitcast it to be a vector type we can extract from.
1648 if (VecTy->getElementType() != DestTy) {
1649 VecTy = VectorType::get(DestTy,
1650 VecTy->getPrimitiveSizeInBits() / DestWidth);
1651 VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
1654 unsigned Elt = ShAmt->getZExtValue() / DestWidth;
1655 return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
1661 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
1662 // If the operands are integer typed then apply the integer transforms,
1663 // otherwise just apply the common ones.
1664 Value *Src = CI.getOperand(0);
1665 Type *SrcTy = Src->getType();
1666 Type *DestTy = CI.getType();
1668 // Get rid of casts from one type to the same type. These are useless and can
1669 // be replaced by the operand.
1670 if (DestTy == Src->getType())
1671 return ReplaceInstUsesWith(CI, Src);
1673 if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
1674 PointerType *SrcPTy = cast<PointerType>(SrcTy);
1675 Type *DstElTy = DstPTy->getElementType();
1676 Type *SrcElTy = SrcPTy->getElementType();
1678 // If the address spaces don't match, don't eliminate the bitcast, which is
1679 // required for changing types.
1680 if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
1683 // If we are casting a alloca to a pointer to a type of the same
1684 // size, rewrite the allocation instruction to allocate the "right" type.
1685 // There is no need to modify malloc calls because it is their bitcast that
1686 // needs to be cleaned up.
1687 if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
1688 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
1691 // If the source and destination are pointers, and this cast is equivalent
1692 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
1693 // This can enhance SROA and other transforms that want type-safe pointers.
1694 Constant *ZeroUInt =
1695 Constant::getNullValue(Type::getInt32Ty(CI.getContext()));
1696 unsigned NumZeros = 0;
1697 while (SrcElTy != DstElTy &&
1698 isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
1699 SrcElTy->getNumContainedTypes() /* not "{}" */) {
1700 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
1704 // If we found a path from the src to dest, create the getelementptr now.
1705 if (SrcElTy == DstElTy) {
1706 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
1707 return GetElementPtrInst::CreateInBounds(Src, Idxs);
1711 // Try to optimize int -> float bitcasts.
1712 if ((DestTy->isFloatTy() || DestTy->isDoubleTy()) && isa<IntegerType>(SrcTy))
1713 if (Instruction *I = OptimizeIntToFloatBitCast(CI, *this))
1716 if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
1717 if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
1718 Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
1719 return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
1720 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
1721 // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
1724 if (isa<IntegerType>(SrcTy)) {
1725 // If this is a cast from an integer to vector, check to see if the input
1726 // is a trunc or zext of a bitcast from vector. If so, we can replace all
1727 // the casts with a shuffle and (potentially) a bitcast.
1728 if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
1729 CastInst *SrcCast = cast<CastInst>(Src);
1730 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
1731 if (isa<VectorType>(BCIn->getOperand(0)->getType()))
1732 if (Instruction *I = OptimizeVectorResize(BCIn->getOperand(0),
1733 cast<VectorType>(DestTy), *this))
1737 // If the input is an 'or' instruction, we may be doing shifts and ors to
1738 // assemble the elements of the vector manually. Try to rip the code out
1739 // and replace it with insertelements.
1740 if (Value *V = OptimizeIntegerToVectorInsertions(CI, *this))
1741 return ReplaceInstUsesWith(CI, V);
1745 if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
1746 if (SrcVTy->getNumElements() == 1 && !DestTy->isVectorTy()) {
1748 Builder->CreateExtractElement(Src,
1749 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
1750 return CastInst::Create(Instruction::BitCast, Elem, DestTy);
1754 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
1755 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
1756 // a bitcast to a vector with the same # elts.
1757 if (SVI->hasOneUse() && DestTy->isVectorTy() &&
1758 cast<VectorType>(DestTy)->getNumElements() ==
1759 SVI->getType()->getNumElements() &&
1760 SVI->getType()->getNumElements() ==
1761 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
1763 // If either of the operands is a cast from CI.getType(), then
1764 // evaluating the shuffle in the casted destination's type will allow
1765 // us to eliminate at least one cast.
1766 if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
1767 Tmp->getOperand(0)->getType() == DestTy) ||
1768 ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
1769 Tmp->getOperand(0)->getType() == DestTy)) {
1770 Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
1771 Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
1772 // Return a new shuffle vector. Use the same element ID's, as we
1773 // know the vector types match #elts.
1774 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
1779 if (SrcTy->isPointerTy())
1780 return commonPointerCastTransforms(CI);
1781 return commonCastTransforms(CI);