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/Target/TargetData.h"
16 #include "llvm/Support/PatternMatch.h"
18 using namespace PatternMatch;
20 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
21 /// expression. If so, decompose it, returning some value X, such that Val is
24 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
26 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
27 Offset = CI->getZExtValue();
29 return ConstantInt::get(Val->getType(), 0);
32 if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
33 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
34 if (I->getOpcode() == Instruction::Shl) {
35 // This is a value scaled by '1 << the shift amt'.
36 Scale = UINT64_C(1) << RHS->getZExtValue();
38 return I->getOperand(0);
41 if (I->getOpcode() == Instruction::Mul) {
42 // This value is scaled by 'RHS'.
43 Scale = RHS->getZExtValue();
45 return I->getOperand(0);
48 if (I->getOpcode() == Instruction::Add) {
49 // We have X+C. Check to see if we really have (X*C2)+C1,
50 // where C1 is divisible by C2.
53 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
54 Offset += RHS->getZExtValue();
61 // Otherwise, we can't look past this.
67 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
68 /// try to eliminate the cast by moving the type information into the alloc.
69 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
71 // This requires TargetData to get the alloca alignment and size information.
74 const PointerType *PTy = cast<PointerType>(CI.getType());
76 BuilderTy AllocaBuilder(*Builder);
77 AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
79 // Get the type really allocated and the type casted to.
80 const Type *AllocElTy = AI.getAllocatedType();
81 const Type *CastElTy = PTy->getElementType();
82 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
84 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
85 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
86 if (CastElTyAlign < AllocElTyAlign) return 0;
88 // If the allocation has multiple uses, only promote it if we are strictly
89 // increasing the alignment of the resultant allocation. If we keep it the
90 // same, we open the door to infinite loops of various kinds.
91 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
93 uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
94 uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
95 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
97 // See if we can satisfy the modulus by pulling a scale out of the array
99 unsigned ArraySizeScale;
100 uint64_t ArrayOffset;
101 Value *NumElements = // See if the array size is a decomposable linear expr.
102 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
104 // If we can now satisfy the modulus, by using a non-1 scale, we really can
106 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
107 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
109 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
114 Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale);
115 // Insert before the alloca, not before the cast.
116 Amt = AllocaBuilder.CreateMul(Amt, NumElements, "tmp");
119 if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
120 Value *Off = ConstantInt::get(AI.getArraySize()->getType(),
122 Amt = AllocaBuilder.CreateAdd(Amt, Off, "tmp");
125 AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
126 New->setAlignment(AI.getAlignment());
129 // If the allocation has multiple real uses, insert a cast and change all
130 // things that used it to use the new cast. This will also hack on CI, but it
132 if (!AI.hasOneUse()) {
133 // New is the allocation instruction, pointer typed. AI is the original
134 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
135 Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
136 AI.replaceAllUsesWith(NewCast);
138 return ReplaceInstUsesWith(CI, New);
143 /// EvaluateInDifferentType - Given an expression that
144 /// CanEvaluateTruncated or CanEvaluateSExtd returns true for, actually
145 /// insert the code to evaluate the expression.
146 Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
148 if (Constant *C = dyn_cast<Constant>(V)) {
149 C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
150 // If we got a constantexpr back, try to simplify it with TD info.
151 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
152 C = ConstantFoldConstantExpression(CE, TD);
156 // Otherwise, it must be an instruction.
157 Instruction *I = cast<Instruction>(V);
158 Instruction *Res = 0;
159 unsigned Opc = I->getOpcode();
161 case Instruction::Add:
162 case Instruction::Sub:
163 case Instruction::Mul:
164 case Instruction::And:
165 case Instruction::Or:
166 case Instruction::Xor:
167 case Instruction::AShr:
168 case Instruction::LShr:
169 case Instruction::Shl:
170 case Instruction::UDiv:
171 case Instruction::URem: {
172 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
173 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
174 Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
177 case Instruction::Trunc:
178 case Instruction::ZExt:
179 case Instruction::SExt:
180 // If the source type of the cast is the type we're trying for then we can
181 // just return the source. There's no need to insert it because it is not
183 if (I->getOperand(0)->getType() == Ty)
184 return I->getOperand(0);
186 // Otherwise, must be the same type of cast, so just reinsert a new one.
187 // This also handles the case of zext(trunc(x)) -> zext(x).
188 Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty,
189 Opc == Instruction::SExt);
191 case Instruction::Select: {
192 Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
193 Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
194 Res = SelectInst::Create(I->getOperand(0), True, False);
197 case Instruction::PHI: {
198 PHINode *OPN = cast<PHINode>(I);
199 PHINode *NPN = PHINode::Create(Ty);
200 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
201 Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
202 NPN->addIncoming(V, OPN->getIncomingBlock(i));
208 // TODO: Can handle more cases here.
209 llvm_unreachable("Unreachable!");
214 return InsertNewInstBefore(Res, *I);
218 /// This function is a wrapper around CastInst::isEliminableCastPair. It
219 /// simply extracts arguments and returns what that function returns.
220 static Instruction::CastOps
221 isEliminableCastPair(
222 const CastInst *CI, ///< The first cast instruction
223 unsigned opcode, ///< The opcode of the second cast instruction
224 const Type *DstTy, ///< The target type for the second cast instruction
225 TargetData *TD ///< The target data for pointer size
228 const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
229 const Type *MidTy = CI->getType(); // B from above
231 // Get the opcodes of the two Cast instructions
232 Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
233 Instruction::CastOps secondOp = Instruction::CastOps(opcode);
235 unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
237 TD ? TD->getIntPtrType(CI->getContext()) : 0);
239 // We don't want to form an inttoptr or ptrtoint that converts to an integer
240 // type that differs from the pointer size.
241 if ((Res == Instruction::IntToPtr &&
242 (!TD || SrcTy != TD->getIntPtrType(CI->getContext()))) ||
243 (Res == Instruction::PtrToInt &&
244 (!TD || DstTy != TD->getIntPtrType(CI->getContext()))))
247 return Instruction::CastOps(Res);
250 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
251 /// results in any code being generated and is interesting to optimize out. If
252 /// the cast can be eliminated by some other simple transformation, we prefer
253 /// to do the simplification first.
254 bool InstCombiner::ShouldOptimizeCast(Instruction::CastOps opc, const Value *V,
256 // Noop casts and casts of constants should be eliminated trivially.
257 if (V->getType() == Ty || isa<Constant>(V)) return false;
259 // If this is another cast that can be eliminated, we prefer to have it
261 if (const CastInst *CI = dyn_cast<CastInst>(V))
262 if (isEliminableCastPair(CI, opc, Ty, TD))
265 // If this is a vector sext from a compare, then we don't want to break the
266 // idiom where each element of the extended vector is either zero or all ones.
267 if (opc == Instruction::SExt && isa<CmpInst>(V) && Ty->isVectorTy())
274 /// @brief Implement the transforms common to all CastInst visitors.
275 Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
276 Value *Src = CI.getOperand(0);
278 // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
280 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
281 if (Instruction::CastOps opc =
282 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
283 // The first cast (CSrc) is eliminable so we need to fix up or replace
284 // the second cast (CI). CSrc will then have a good chance of being dead.
285 return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
289 // If we are casting a select then fold the cast into the select
290 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
291 if (Instruction *NV = FoldOpIntoSelect(CI, SI))
294 // If we are casting a PHI then fold the cast into the PHI
295 if (isa<PHINode>(Src)) {
296 // We don't do this if this would create a PHI node with an illegal type if
297 // it is currently legal.
298 if (!Src->getType()->isIntegerTy() ||
299 !CI.getType()->isIntegerTy() ||
300 ShouldChangeType(CI.getType(), Src->getType()))
301 if (Instruction *NV = FoldOpIntoPhi(CI))
308 /// CanEvaluateTruncated - Return true if we can evaluate the specified
309 /// expression tree as type Ty instead of its larger type, and arrive with the
310 /// same value. This is used by code that tries to eliminate truncates.
312 /// Ty will always be a type smaller than V. We should return true if trunc(V)
313 /// can be computed by computing V in the smaller type. If V is an instruction,
314 /// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only
315 /// makes sense if x and y can be efficiently truncated.
317 /// This function works on both vectors and scalars.
319 static bool CanEvaluateTruncated(Value *V, const Type *Ty) {
320 // We can always evaluate constants in another type.
321 if (isa<Constant>(V))
324 Instruction *I = dyn_cast<Instruction>(V);
325 if (!I) return false;
327 const Type *OrigTy = V->getType();
329 // If this is an extension from the dest type, we can eliminate it, even if it
330 // has multiple uses.
331 if ((isa<ZExtInst>(I) || isa<SExtInst>(I)) &&
332 I->getOperand(0)->getType() == Ty)
335 // We can't extend or shrink something that has multiple uses: doing so would
336 // require duplicating the instruction in general, which isn't profitable.
337 if (!I->hasOneUse()) return false;
339 unsigned Opc = I->getOpcode();
341 case Instruction::Add:
342 case Instruction::Sub:
343 case Instruction::Mul:
344 case Instruction::And:
345 case Instruction::Or:
346 case Instruction::Xor:
347 // These operators can all arbitrarily be extended or truncated.
348 return CanEvaluateTruncated(I->getOperand(0), Ty) &&
349 CanEvaluateTruncated(I->getOperand(1), Ty);
351 case Instruction::UDiv:
352 case Instruction::URem: {
353 // UDiv and URem can be truncated if all the truncated bits are zero.
354 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
355 uint32_t BitWidth = Ty->getScalarSizeInBits();
356 if (BitWidth < OrigBitWidth) {
357 APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
358 if (MaskedValueIsZero(I->getOperand(0), Mask) &&
359 MaskedValueIsZero(I->getOperand(1), Mask)) {
360 return CanEvaluateTruncated(I->getOperand(0), Ty) &&
361 CanEvaluateTruncated(I->getOperand(1), Ty);
366 case Instruction::Shl:
367 // If we are truncating the result of this SHL, and if it's a shift of a
368 // constant amount, we can always perform a SHL in a smaller type.
369 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
370 uint32_t BitWidth = Ty->getScalarSizeInBits();
371 if (CI->getLimitedValue(BitWidth) < BitWidth)
372 return CanEvaluateTruncated(I->getOperand(0), Ty);
375 case Instruction::LShr:
376 // If this is a truncate of a logical shr, we can truncate it to a smaller
377 // lshr iff we know that the bits we would otherwise be shifting in are
379 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
380 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
381 uint32_t BitWidth = Ty->getScalarSizeInBits();
382 if (MaskedValueIsZero(I->getOperand(0),
383 APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
384 CI->getLimitedValue(BitWidth) < BitWidth) {
385 return CanEvaluateTruncated(I->getOperand(0), Ty);
389 case Instruction::Trunc:
390 // trunc(trunc(x)) -> trunc(x)
392 case Instruction::ZExt:
393 case Instruction::SExt:
394 // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest
395 // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest
397 case Instruction::Select: {
398 SelectInst *SI = cast<SelectInst>(I);
399 return CanEvaluateTruncated(SI->getTrueValue(), Ty) &&
400 CanEvaluateTruncated(SI->getFalseValue(), Ty);
402 case Instruction::PHI: {
403 // We can change a phi if we can change all operands. Note that we never
404 // get into trouble with cyclic PHIs here because we only consider
405 // instructions with a single use.
406 PHINode *PN = cast<PHINode>(I);
407 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
408 if (!CanEvaluateTruncated(PN->getIncomingValue(i), Ty))
413 // TODO: Can handle more cases here.
420 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
421 if (Instruction *Result = commonCastTransforms(CI))
424 // See if we can simplify any instructions used by the input whose sole
425 // purpose is to compute bits we don't care about.
426 if (SimplifyDemandedInstructionBits(CI))
429 Value *Src = CI.getOperand(0);
430 const Type *DestTy = CI.getType(), *SrcTy = Src->getType();
432 // Attempt to truncate the entire input expression tree to the destination
433 // type. Only do this if the dest type is a simple type, don't convert the
434 // expression tree to something weird like i93 unless the source is also
436 if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
437 CanEvaluateTruncated(Src, DestTy)) {
439 // If this cast is a truncate, evaluting in a different type always
440 // eliminates the cast, so it is always a win.
441 DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
442 " to avoid cast: " << CI << '\n');
443 Value *Res = EvaluateInDifferentType(Src, DestTy, false);
444 assert(Res->getType() == DestTy);
445 return ReplaceInstUsesWith(CI, Res);
448 // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0), likewise for vector.
449 if (DestTy->getScalarSizeInBits() == 1) {
450 Constant *One = ConstantInt::get(Src->getType(), 1);
451 Src = Builder->CreateAnd(Src, One, "tmp");
452 Value *Zero = Constant::getNullValue(Src->getType());
453 return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
456 // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
457 Value *A = 0; ConstantInt *Cst = 0;
458 if (Src->hasOneUse() &&
459 match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
460 // We have three types to worry about here, the type of A, the source of
461 // the truncate (MidSize), and the destination of the truncate. We know that
462 // ASize < MidSize and MidSize > ResultSize, but don't know the relation
463 // between ASize and ResultSize.
464 unsigned ASize = A->getType()->getPrimitiveSizeInBits();
466 // If the shift amount is larger than the size of A, then the result is
467 // known to be zero because all the input bits got shifted out.
468 if (Cst->getZExtValue() >= ASize)
469 return ReplaceInstUsesWith(CI, Constant::getNullValue(CI.getType()));
471 // Since we're doing an lshr and a zero extend, and know that the shift
472 // amount is smaller than ASize, it is always safe to do the shift in A's
473 // type, then zero extend or truncate to the result.
474 Value *Shift = Builder->CreateLShr(A, Cst->getZExtValue());
475 Shift->takeName(Src);
476 return CastInst::CreateIntegerCast(Shift, CI.getType(), false);
479 // Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
480 // type isn't non-native.
481 if (Src->hasOneUse() && isa<IntegerType>(Src->getType()) &&
482 ShouldChangeType(Src->getType(), CI.getType()) &&
483 match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
484 Value *NewTrunc = Builder->CreateTrunc(A, CI.getType(), A->getName()+".tr");
485 return BinaryOperator::CreateAnd(NewTrunc,
486 ConstantExpr::getTrunc(Cst, CI.getType()));
492 /// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
493 /// in order to eliminate the icmp.
494 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
496 // If we are just checking for a icmp eq of a single bit and zext'ing it
497 // to an integer, then shift the bit to the appropriate place and then
498 // cast to integer to avoid the comparison.
499 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
500 const APInt &Op1CV = Op1C->getValue();
502 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
503 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
504 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
505 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
506 if (!DoXform) return ICI;
508 Value *In = ICI->getOperand(0);
509 Value *Sh = ConstantInt::get(In->getType(),
510 In->getType()->getScalarSizeInBits()-1);
511 In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
512 if (In->getType() != CI.getType())
513 In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/, "tmp");
515 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
516 Constant *One = ConstantInt::get(In->getType(), 1);
517 In = Builder->CreateXor(In, One, In->getName()+".not");
520 return ReplaceInstUsesWith(CI, In);
525 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
526 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
527 // zext (X == 1) to i32 --> X iff X has only the low bit set.
528 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
529 // zext (X != 0) to i32 --> X iff X has only the low bit set.
530 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
531 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
532 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
533 if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
534 // This only works for EQ and NE
536 // If Op1C some other power of two, convert:
537 uint32_t BitWidth = Op1C->getType()->getBitWidth();
538 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
539 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
540 ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
542 APInt KnownZeroMask(~KnownZero);
543 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
544 if (!DoXform) return ICI;
546 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
547 if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
548 // (X&4) == 2 --> false
549 // (X&4) != 2 --> true
550 Constant *Res = ConstantInt::get(Type::getInt1Ty(CI.getContext()),
552 Res = ConstantExpr::getZExt(Res, CI.getType());
553 return ReplaceInstUsesWith(CI, Res);
556 uint32_t ShiftAmt = KnownZeroMask.logBase2();
557 Value *In = ICI->getOperand(0);
559 // Perform a logical shr by shiftamt.
560 // Insert the shift to put the result in the low bit.
561 In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
562 In->getName()+".lobit");
565 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
566 Constant *One = ConstantInt::get(In->getType(), 1);
567 In = Builder->CreateXor(In, One, "tmp");
570 if (CI.getType() == In->getType())
571 return ReplaceInstUsesWith(CI, In);
572 return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
577 // icmp ne A, B is equal to xor A, B when A and B only really have one bit.
578 // It is also profitable to transform icmp eq into not(xor(A, B)) because that
579 // may lead to additional simplifications.
580 if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) {
581 if (const IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
582 uint32_t BitWidth = ITy->getBitWidth();
583 Value *LHS = ICI->getOperand(0);
584 Value *RHS = ICI->getOperand(1);
586 APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
587 APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
588 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
589 ComputeMaskedBits(LHS, TypeMask, KnownZeroLHS, KnownOneLHS);
590 ComputeMaskedBits(RHS, TypeMask, KnownZeroRHS, KnownOneRHS);
592 if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) {
593 APInt KnownBits = KnownZeroLHS | KnownOneLHS;
594 APInt UnknownBit = ~KnownBits;
595 if (UnknownBit.countPopulation() == 1) {
596 if (!DoXform) return ICI;
598 Value *Result = Builder->CreateXor(LHS, RHS);
600 // Mask off any bits that are set and won't be shifted away.
601 if (KnownOneLHS.uge(UnknownBit))
602 Result = Builder->CreateAnd(Result,
603 ConstantInt::get(ITy, UnknownBit));
605 // Shift the bit we're testing down to the lsb.
606 Result = Builder->CreateLShr(
607 Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros()));
609 if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
610 Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1));
611 Result->takeName(ICI);
612 return ReplaceInstUsesWith(CI, Result);
621 /// CanEvaluateZExtd - Determine if the specified value can be computed in the
622 /// specified wider type and produce the same low bits. If not, return false.
624 /// If this function returns true, it can also return a non-zero number of bits
625 /// (in BitsToClear) which indicates that the value it computes is correct for
626 /// the zero extend, but that the additional BitsToClear bits need to be zero'd
627 /// out. For example, to promote something like:
629 /// %B = trunc i64 %A to i32
630 /// %C = lshr i32 %B, 8
631 /// %E = zext i32 %C to i64
633 /// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be
634 /// set to 8 to indicate that the promoted value needs to have bits 24-31
635 /// cleared in addition to bits 32-63. Since an 'and' will be generated to
636 /// clear the top bits anyway, doing this has no extra cost.
638 /// This function works on both vectors and scalars.
639 static bool CanEvaluateZExtd(Value *V, const Type *Ty, unsigned &BitsToClear) {
641 if (isa<Constant>(V))
644 Instruction *I = dyn_cast<Instruction>(V);
645 if (!I) return false;
647 // If the input is a truncate from the destination type, we can trivially
648 // eliminate it, even if it has multiple uses.
649 // FIXME: This is currently disabled until codegen can handle this without
650 // pessimizing code, PR5997.
651 if (0 && isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
654 // We can't extend or shrink something that has multiple uses: doing so would
655 // require duplicating the instruction in general, which isn't profitable.
656 if (!I->hasOneUse()) return false;
658 unsigned Opc = I->getOpcode(), Tmp;
660 case Instruction::ZExt: // zext(zext(x)) -> zext(x).
661 case Instruction::SExt: // zext(sext(x)) -> sext(x).
662 case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x)
664 case Instruction::And:
665 case Instruction::Or:
666 case Instruction::Xor:
667 case Instruction::Add:
668 case Instruction::Sub:
669 case Instruction::Mul:
670 case Instruction::Shl:
671 if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear) ||
672 !CanEvaluateZExtd(I->getOperand(1), Ty, Tmp))
674 // These can all be promoted if neither operand has 'bits to clear'.
675 if (BitsToClear == 0 && Tmp == 0)
678 // If the operation is an AND/OR/XOR and the bits to clear are zero in the
679 // other side, BitsToClear is ok.
681 (Opc == Instruction::And || Opc == Instruction::Or ||
682 Opc == Instruction::Xor)) {
683 // We use MaskedValueIsZero here for generality, but the case we care
684 // about the most is constant RHS.
685 unsigned VSize = V->getType()->getScalarSizeInBits();
686 if (MaskedValueIsZero(I->getOperand(1),
687 APInt::getHighBitsSet(VSize, BitsToClear)))
691 // Otherwise, we don't know how to analyze this BitsToClear case yet.
694 case Instruction::LShr:
695 // We can promote lshr(x, cst) if we can promote x. This requires the
696 // ultimate 'and' to clear out the high zero bits we're clearing out though.
697 if (ConstantInt *Amt = dyn_cast<ConstantInt>(I->getOperand(1))) {
698 if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear))
700 BitsToClear += Amt->getZExtValue();
701 if (BitsToClear > V->getType()->getScalarSizeInBits())
702 BitsToClear = V->getType()->getScalarSizeInBits();
705 // Cannot promote variable LSHR.
707 case Instruction::Select:
708 if (!CanEvaluateZExtd(I->getOperand(1), Ty, Tmp) ||
709 !CanEvaluateZExtd(I->getOperand(2), Ty, BitsToClear) ||
710 // TODO: If important, we could handle the case when the BitsToClear are
711 // known zero in the disagreeing side.
716 case Instruction::PHI: {
717 // We can change a phi if we can change all operands. Note that we never
718 // get into trouble with cyclic PHIs here because we only consider
719 // instructions with a single use.
720 PHINode *PN = cast<PHINode>(I);
721 if (!CanEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear))
723 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
724 if (!CanEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp) ||
725 // TODO: If important, we could handle the case when the BitsToClear
726 // are known zero in the disagreeing input.
732 // TODO: Can handle more cases here.
737 Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
738 // If this zero extend is only used by a truncate, let the truncate by
739 // eliminated before we try to optimize this zext.
740 if (CI.hasOneUse() && isa<TruncInst>(CI.use_back()))
743 // If one of the common conversion will work, do it.
744 if (Instruction *Result = commonCastTransforms(CI))
747 // See if we can simplify any instructions used by the input whose sole
748 // purpose is to compute bits we don't care about.
749 if (SimplifyDemandedInstructionBits(CI))
752 Value *Src = CI.getOperand(0);
753 const Type *SrcTy = Src->getType(), *DestTy = CI.getType();
755 // Attempt to extend the entire input expression tree to the destination
756 // type. Only do this if the dest type is a simple type, don't convert the
757 // expression tree to something weird like i93 unless the source is also
759 unsigned BitsToClear;
760 if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
761 CanEvaluateZExtd(Src, DestTy, BitsToClear)) {
762 assert(BitsToClear < SrcTy->getScalarSizeInBits() &&
763 "Unreasonable BitsToClear");
765 // Okay, we can transform this! Insert the new expression now.
766 DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
767 " to avoid zero extend: " << CI);
768 Value *Res = EvaluateInDifferentType(Src, DestTy, false);
769 assert(Res->getType() == DestTy);
771 uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
772 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
774 // If the high bits are already filled with zeros, just replace this
775 // cast with the result.
776 if (MaskedValueIsZero(Res, APInt::getHighBitsSet(DestBitSize,
777 DestBitSize-SrcBitsKept)))
778 return ReplaceInstUsesWith(CI, Res);
780 // We need to emit an AND to clear the high bits.
781 Constant *C = ConstantInt::get(Res->getType(),
782 APInt::getLowBitsSet(DestBitSize, SrcBitsKept));
783 return BinaryOperator::CreateAnd(Res, C);
786 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
787 // types and if the sizes are just right we can convert this into a logical
788 // 'and' which will be much cheaper than the pair of casts.
789 if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
790 // TODO: Subsume this into EvaluateInDifferentType.
792 // Get the sizes of the types involved. We know that the intermediate type
793 // will be smaller than A or C, but don't know the relation between A and C.
794 Value *A = CSrc->getOperand(0);
795 unsigned SrcSize = A->getType()->getScalarSizeInBits();
796 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
797 unsigned DstSize = CI.getType()->getScalarSizeInBits();
798 // If we're actually extending zero bits, then if
799 // SrcSize < DstSize: zext(a & mask)
800 // SrcSize == DstSize: a & mask
801 // SrcSize > DstSize: trunc(a) & mask
802 if (SrcSize < DstSize) {
803 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
804 Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
805 Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
806 return new ZExtInst(And, CI.getType());
809 if (SrcSize == DstSize) {
810 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
811 return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
814 if (SrcSize > DstSize) {
815 Value *Trunc = Builder->CreateTrunc(A, CI.getType(), "tmp");
816 APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
817 return BinaryOperator::CreateAnd(Trunc,
818 ConstantInt::get(Trunc->getType(),
823 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
824 return transformZExtICmp(ICI, CI);
826 BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
827 if (SrcI && SrcI->getOpcode() == Instruction::Or) {
828 // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
829 // of the (zext icmp) will be transformed.
830 ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
831 ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
832 if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
833 (transformZExtICmp(LHS, CI, false) ||
834 transformZExtICmp(RHS, CI, false))) {
835 Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
836 Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
837 return BinaryOperator::Create(Instruction::Or, LCast, RCast);
841 // zext(trunc(t) & C) -> (t & zext(C)).
842 if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
843 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
844 if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
845 Value *TI0 = TI->getOperand(0);
846 if (TI0->getType() == CI.getType())
848 BinaryOperator::CreateAnd(TI0,
849 ConstantExpr::getZExt(C, CI.getType()));
852 // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
853 if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
854 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
855 if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
856 if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
857 And->getOperand(1) == C)
858 if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
859 Value *TI0 = TI->getOperand(0);
860 if (TI0->getType() == CI.getType()) {
861 Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
862 Value *NewAnd = Builder->CreateAnd(TI0, ZC, "tmp");
863 return BinaryOperator::CreateXor(NewAnd, ZC);
867 // zext (xor i1 X, true) to i32 --> xor (zext i1 X to i32), 1
869 if (SrcI && SrcI->hasOneUse() && SrcI->getType()->isIntegerTy(1) &&
870 match(SrcI, m_Not(m_Value(X))) &&
871 (!X->hasOneUse() || !isa<CmpInst>(X))) {
872 Value *New = Builder->CreateZExt(X, CI.getType());
873 return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1));
879 /// CanEvaluateSExtd - Return true if we can take the specified value
880 /// and return it as type Ty without inserting any new casts and without
881 /// changing the value of the common low bits. This is used by code that tries
882 /// to promote integer operations to a wider types will allow us to eliminate
885 /// This function works on both vectors and scalars.
887 static bool CanEvaluateSExtd(Value *V, const Type *Ty) {
888 assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() &&
889 "Can't sign extend type to a smaller type");
890 // If this is a constant, it can be trivially promoted.
891 if (isa<Constant>(V))
894 Instruction *I = dyn_cast<Instruction>(V);
895 if (!I) return false;
897 // If this is a truncate from the dest type, we can trivially eliminate it,
898 // even if it has multiple uses.
899 // FIXME: This is currently disabled until codegen can handle this without
900 // pessimizing code, PR5997.
901 if (0 && isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
904 // We can't extend or shrink something that has multiple uses: doing so would
905 // require duplicating the instruction in general, which isn't profitable.
906 if (!I->hasOneUse()) return false;
908 switch (I->getOpcode()) {
909 case Instruction::SExt: // sext(sext(x)) -> sext(x)
910 case Instruction::ZExt: // sext(zext(x)) -> zext(x)
911 case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x)
913 case Instruction::And:
914 case Instruction::Or:
915 case Instruction::Xor:
916 case Instruction::Add:
917 case Instruction::Sub:
918 case Instruction::Mul:
919 // These operators can all arbitrarily be extended if their inputs can.
920 return CanEvaluateSExtd(I->getOperand(0), Ty) &&
921 CanEvaluateSExtd(I->getOperand(1), Ty);
923 //case Instruction::Shl: TODO
924 //case Instruction::LShr: TODO
926 case Instruction::Select:
927 return CanEvaluateSExtd(I->getOperand(1), Ty) &&
928 CanEvaluateSExtd(I->getOperand(2), Ty);
930 case Instruction::PHI: {
931 // We can change a phi if we can change all operands. Note that we never
932 // get into trouble with cyclic PHIs here because we only consider
933 // instructions with a single use.
934 PHINode *PN = cast<PHINode>(I);
935 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
936 if (!CanEvaluateSExtd(PN->getIncomingValue(i), Ty)) return false;
940 // TODO: Can handle more cases here.
947 Instruction *InstCombiner::visitSExt(SExtInst &CI) {
948 // If this sign extend is only used by a truncate, let the truncate by
949 // eliminated before we try to optimize this zext.
950 if (CI.hasOneUse() && isa<TruncInst>(CI.use_back()))
953 if (Instruction *I = commonCastTransforms(CI))
956 // See if we can simplify any instructions used by the input whose sole
957 // purpose is to compute bits we don't care about.
958 if (SimplifyDemandedInstructionBits(CI))
961 Value *Src = CI.getOperand(0);
962 const Type *SrcTy = Src->getType(), *DestTy = CI.getType();
964 // Attempt to extend the entire input expression tree to the destination
965 // type. Only do this if the dest type is a simple type, don't convert the
966 // expression tree to something weird like i93 unless the source is also
968 if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) &&
969 CanEvaluateSExtd(Src, DestTy)) {
970 // Okay, we can transform this! Insert the new expression now.
971 DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type"
972 " to avoid sign extend: " << CI);
973 Value *Res = EvaluateInDifferentType(Src, DestTy, true);
974 assert(Res->getType() == DestTy);
976 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
977 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
979 // If the high bits are already filled with sign bit, just replace this
980 // cast with the result.
981 if (ComputeNumSignBits(Res) > DestBitSize - SrcBitSize)
982 return ReplaceInstUsesWith(CI, Res);
984 // We need to emit a shl + ashr to do the sign extend.
985 Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
986 return BinaryOperator::CreateAShr(Builder->CreateShl(Res, ShAmt, "sext"),
990 // If this input is a trunc from our destination, then turn sext(trunc(x))
992 if (TruncInst *TI = dyn_cast<TruncInst>(Src))
993 if (TI->hasOneUse() && TI->getOperand(0)->getType() == DestTy) {
994 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
995 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
997 // We need to emit a shl + ashr to do the sign extend.
998 Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize);
999 Value *Res = Builder->CreateShl(TI->getOperand(0), ShAmt, "sext");
1000 return BinaryOperator::CreateAShr(Res, ShAmt);
1004 // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
1005 // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
1007 ICmpInst::Predicate Pred; Value *CmpLHS; ConstantInt *CmpRHS;
1008 if (match(Src, m_ICmp(Pred, m_Value(CmpLHS), m_ConstantInt(CmpRHS)))) {
1009 // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
1010 // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
1011 if ((Pred == ICmpInst::ICMP_SLT && CmpRHS->isZero()) ||
1012 (Pred == ICmpInst::ICMP_SGT && CmpRHS->isAllOnesValue())) {
1013 Value *Sh = ConstantInt::get(CmpLHS->getType(),
1014 CmpLHS->getType()->getScalarSizeInBits()-1);
1015 Value *In = Builder->CreateAShr(CmpLHS, Sh, CmpLHS->getName()+".lobit");
1016 if (In->getType() != CI.getType())
1017 In = Builder->CreateIntCast(In, CI.getType(), true/*SExt*/, "tmp");
1019 if (Pred == ICmpInst::ICMP_SGT)
1020 In = Builder->CreateNot(In, In->getName()+".not");
1021 return ReplaceInstUsesWith(CI, In);
1026 // vector (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed.
1027 if (const VectorType *VTy = dyn_cast<VectorType>(DestTy)) {
1028 ICmpInst::Predicate Pred; Value *CmpLHS;
1029 if (match(Src, m_ICmp(Pred, m_Value(CmpLHS), m_Zero()))) {
1030 if (Pred == ICmpInst::ICMP_SLT && CmpLHS->getType() == DestTy) {
1031 const Type *EltTy = VTy->getElementType();
1033 // splat the shift constant to a constant vector.
1034 Constant *VSh = ConstantInt::get(VTy, EltTy->getScalarSizeInBits()-1);
1035 Value *In = Builder->CreateAShr(CmpLHS, VSh,CmpLHS->getName()+".lobit");
1036 return ReplaceInstUsesWith(CI, In);
1041 // If the input is a shl/ashr pair of a same constant, then this is a sign
1042 // extension from a smaller value. If we could trust arbitrary bitwidth
1043 // integers, we could turn this into a truncate to the smaller bit and then
1044 // use a sext for the whole extension. Since we don't, look deeper and check
1045 // for a truncate. If the source and dest are the same type, eliminate the
1046 // trunc and extend and just do shifts. For example, turn:
1047 // %a = trunc i32 %i to i8
1048 // %b = shl i8 %a, 6
1049 // %c = ashr i8 %b, 6
1050 // %d = sext i8 %c to i32
1052 // %a = shl i32 %i, 30
1053 // %d = ashr i32 %a, 30
1055 // TODO: Eventually this could be subsumed by EvaluateInDifferentType.
1056 ConstantInt *BA = 0, *CA = 0;
1057 if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)),
1058 m_ConstantInt(CA))) &&
1059 BA == CA && A->getType() == CI.getType()) {
1060 unsigned MidSize = Src->getType()->getScalarSizeInBits();
1061 unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
1062 unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
1063 Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
1064 A = Builder->CreateShl(A, ShAmtV, CI.getName());
1065 return BinaryOperator::CreateAShr(A, ShAmtV);
1072 /// FitsInFPType - Return a Constant* for the specified FP constant if it fits
1073 /// in the specified FP type without changing its value.
1074 static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
1076 APFloat F = CFP->getValueAPF();
1077 (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
1079 return ConstantFP::get(CFP->getContext(), F);
1083 /// LookThroughFPExtensions - If this is an fp extension instruction, look
1084 /// through it until we get the source value.
1085 static Value *LookThroughFPExtensions(Value *V) {
1086 if (Instruction *I = dyn_cast<Instruction>(V))
1087 if (I->getOpcode() == Instruction::FPExt)
1088 return LookThroughFPExtensions(I->getOperand(0));
1090 // If this value is a constant, return the constant in the smallest FP type
1091 // that can accurately represent it. This allows us to turn
1092 // (float)((double)X+2.0) into x+2.0f.
1093 if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
1094 if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext()))
1095 return V; // No constant folding of this.
1096 // See if the value can be truncated to float and then reextended.
1097 if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
1099 if (CFP->getType()->isDoubleTy())
1100 return V; // Won't shrink.
1101 if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble))
1103 // Don't try to shrink to various long double types.
1109 Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
1110 if (Instruction *I = commonCastTransforms(CI))
1113 // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are
1114 // smaller than the destination type, we can eliminate the truncate by doing
1115 // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well
1116 // as many builtins (sqrt, etc).
1117 BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
1118 if (OpI && OpI->hasOneUse()) {
1119 switch (OpI->getOpcode()) {
1121 case Instruction::FAdd:
1122 case Instruction::FSub:
1123 case Instruction::FMul:
1124 case Instruction::FDiv:
1125 case Instruction::FRem:
1126 const Type *SrcTy = OpI->getType();
1127 Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0));
1128 Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1));
1129 if (LHSTrunc->getType() != SrcTy &&
1130 RHSTrunc->getType() != SrcTy) {
1131 unsigned DstSize = CI.getType()->getScalarSizeInBits();
1132 // If the source types were both smaller than the destination type of
1133 // the cast, do this xform.
1134 if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize &&
1135 RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) {
1136 LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType());
1137 RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType());
1138 return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
1145 // Fold (fptrunc (sqrt (fpext x))) -> (sqrtf x)
1146 // NOTE: This should be disabled by -fno-builtin-sqrt if we ever support it.
1147 CallInst *Call = dyn_cast<CallInst>(CI.getOperand(0));
1148 if (Call && Call->getCalledFunction() &&
1149 Call->getCalledFunction()->getName() == "sqrt" &&
1150 Call->getNumArgOperands() == 1) {
1151 CastInst *Arg = dyn_cast<CastInst>(Call->getArgOperand(0));
1152 if (Arg && Arg->getOpcode() == Instruction::FPExt &&
1153 CI.getType()->isFloatTy() &&
1154 Call->getType()->isDoubleTy() &&
1155 Arg->getType()->isDoubleTy() &&
1156 Arg->getOperand(0)->getType()->isFloatTy()) {
1157 Function *Callee = Call->getCalledFunction();
1158 Module *M = CI.getParent()->getParent()->getParent();
1159 Constant *SqrtfFunc = M->getOrInsertFunction("sqrtf",
1160 Callee->getAttributes(),
1161 Builder->getFloatTy(),
1162 Builder->getFloatTy(),
1164 CallInst *ret = CallInst::Create(SqrtfFunc, Arg->getOperand(0),
1166 ret->setAttributes(Callee->getAttributes());
1169 // Remove the old Call. With -fmath-errno, it won't get marked readnone.
1170 Call->replaceAllUsesWith(UndefValue::get(Call->getType()));
1171 EraseInstFromFunction(*Call);
1179 Instruction *InstCombiner::visitFPExt(CastInst &CI) {
1180 return commonCastTransforms(CI);
1183 Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
1184 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1186 return commonCastTransforms(FI);
1188 // fptoui(uitofp(X)) --> X
1189 // fptoui(sitofp(X)) --> X
1190 // This is safe if the intermediate type has enough bits in its mantissa to
1191 // accurately represent all values of X. For example, do not do this with
1192 // i64->float->i64. This is also safe for sitofp case, because any negative
1193 // 'X' value would cause an undefined result for the fptoui.
1194 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
1195 OpI->getOperand(0)->getType() == FI.getType() &&
1196 (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
1197 OpI->getType()->getFPMantissaWidth())
1198 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
1200 return commonCastTransforms(FI);
1203 Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
1204 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
1206 return commonCastTransforms(FI);
1208 // fptosi(sitofp(X)) --> X
1209 // fptosi(uitofp(X)) --> X
1210 // This is safe if the intermediate type has enough bits in its mantissa to
1211 // accurately represent all values of X. For example, do not do this with
1212 // i64->float->i64. This is also safe for sitofp case, because any negative
1213 // 'X' value would cause an undefined result for the fptoui.
1214 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
1215 OpI->getOperand(0)->getType() == FI.getType() &&
1216 (int)FI.getType()->getScalarSizeInBits() <=
1217 OpI->getType()->getFPMantissaWidth())
1218 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
1220 return commonCastTransforms(FI);
1223 Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
1224 return commonCastTransforms(CI);
1227 Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
1228 return commonCastTransforms(CI);
1231 Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
1232 // If the source integer type is not the intptr_t type for this target, do a
1233 // trunc or zext to the intptr_t type, then inttoptr of it. This allows the
1234 // cast to be exposed to other transforms.
1236 if (CI.getOperand(0)->getType()->getScalarSizeInBits() >
1237 TD->getPointerSizeInBits()) {
1238 Value *P = Builder->CreateTrunc(CI.getOperand(0),
1239 TD->getIntPtrType(CI.getContext()), "tmp");
1240 return new IntToPtrInst(P, CI.getType());
1242 if (CI.getOperand(0)->getType()->getScalarSizeInBits() <
1243 TD->getPointerSizeInBits()) {
1244 Value *P = Builder->CreateZExt(CI.getOperand(0),
1245 TD->getIntPtrType(CI.getContext()), "tmp");
1246 return new IntToPtrInst(P, CI.getType());
1250 if (Instruction *I = commonCastTransforms(CI))
1256 /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
1257 Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
1258 Value *Src = CI.getOperand(0);
1260 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
1261 // If casting the result of a getelementptr instruction with no offset, turn
1262 // this into a cast of the original pointer!
1263 if (GEP->hasAllZeroIndices()) {
1264 // Changing the cast operand is usually not a good idea but it is safe
1265 // here because the pointer operand is being replaced with another
1266 // pointer operand so the opcode doesn't need to change.
1268 CI.setOperand(0, GEP->getOperand(0));
1272 // If the GEP has a single use, and the base pointer is a bitcast, and the
1273 // GEP computes a constant offset, see if we can convert these three
1274 // instructions into fewer. This typically happens with unions and other
1275 // non-type-safe code.
1276 if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0)) &&
1277 GEP->hasAllConstantIndices()) {
1278 // We are guaranteed to get a constant from EmitGEPOffset.
1279 ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP));
1280 int64_t Offset = OffsetV->getSExtValue();
1282 // Get the base pointer input of the bitcast, and the type it points to.
1283 Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
1284 const Type *GEPIdxTy =
1285 cast<PointerType>(OrigBase->getType())->getElementType();
1286 SmallVector<Value*, 8> NewIndices;
1287 if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices)) {
1288 // If we were able to index down into an element, create the GEP
1289 // and bitcast the result. This eliminates one bitcast, potentially
1291 Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
1292 Builder->CreateInBoundsGEP(OrigBase,
1293 NewIndices.begin(), NewIndices.end()) :
1294 Builder->CreateGEP(OrigBase, NewIndices.begin(), NewIndices.end());
1295 NGEP->takeName(GEP);
1297 if (isa<BitCastInst>(CI))
1298 return new BitCastInst(NGEP, CI.getType());
1299 assert(isa<PtrToIntInst>(CI));
1300 return new PtrToIntInst(NGEP, CI.getType());
1305 return commonCastTransforms(CI);
1308 Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
1309 // If the destination integer type is not the intptr_t type for this target,
1310 // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast
1311 // to be exposed to other transforms.
1313 if (CI.getType()->getScalarSizeInBits() < TD->getPointerSizeInBits()) {
1314 Value *P = Builder->CreatePtrToInt(CI.getOperand(0),
1315 TD->getIntPtrType(CI.getContext()),
1317 return new TruncInst(P, CI.getType());
1319 if (CI.getType()->getScalarSizeInBits() > TD->getPointerSizeInBits()) {
1320 Value *P = Builder->CreatePtrToInt(CI.getOperand(0),
1321 TD->getIntPtrType(CI.getContext()),
1323 return new ZExtInst(P, CI.getType());
1327 return commonPointerCastTransforms(CI);
1330 /// OptimizeVectorResize - This input value (which is known to have vector type)
1331 /// is being zero extended or truncated to the specified vector type. Try to
1332 /// replace it with a shuffle (and vector/vector bitcast) if possible.
1334 /// The source and destination vector types may have different element types.
1335 static Instruction *OptimizeVectorResize(Value *InVal, const VectorType *DestTy,
1337 // We can only do this optimization if the output is a multiple of the input
1338 // element size, or the input is a multiple of the output element size.
1339 // Convert the input type to have the same element type as the output.
1340 const VectorType *SrcTy = cast<VectorType>(InVal->getType());
1342 if (SrcTy->getElementType() != DestTy->getElementType()) {
1343 // The input types don't need to be identical, but for now they must be the
1344 // same size. There is no specific reason we couldn't handle things like
1345 // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten
1347 if (SrcTy->getElementType()->getPrimitiveSizeInBits() !=
1348 DestTy->getElementType()->getPrimitiveSizeInBits())
1351 SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements());
1352 InVal = IC.Builder->CreateBitCast(InVal, SrcTy);
1355 // Now that the element types match, get the shuffle mask and RHS of the
1356 // shuffle to use, which depends on whether we're increasing or decreasing the
1357 // size of the input.
1358 SmallVector<Constant*, 16> ShuffleMask;
1360 const IntegerType *Int32Ty = Type::getInt32Ty(SrcTy->getContext());
1362 if (SrcTy->getNumElements() > DestTy->getNumElements()) {
1363 // If we're shrinking the number of elements, just shuffle in the low
1364 // elements from the input and use undef as the second shuffle input.
1365 V2 = UndefValue::get(SrcTy);
1366 for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i)
1367 ShuffleMask.push_back(ConstantInt::get(Int32Ty, i));
1370 // If we're increasing the number of elements, shuffle in all of the
1371 // elements from InVal and fill the rest of the result elements with zeros
1372 // from a constant zero.
1373 V2 = Constant::getNullValue(SrcTy);
1374 unsigned SrcElts = SrcTy->getNumElements();
1375 for (unsigned i = 0, e = SrcElts; i != e; ++i)
1376 ShuffleMask.push_back(ConstantInt::get(Int32Ty, i));
1378 // The excess elements reference the first element of the zero input.
1379 ShuffleMask.append(DestTy->getNumElements()-SrcElts,
1380 ConstantInt::get(Int32Ty, SrcElts));
1383 return new ShuffleVectorInst(InVal, V2, ConstantVector::get(ShuffleMask));
1386 static bool isMultipleOfTypeSize(unsigned Value, const Type *Ty) {
1387 return Value % Ty->getPrimitiveSizeInBits() == 0;
1390 static unsigned getTypeSizeIndex(unsigned Value, const Type *Ty) {
1391 return Value / Ty->getPrimitiveSizeInBits();
1394 /// CollectInsertionElements - V is a value which is inserted into a vector of
1395 /// VecEltTy. Look through the value to see if we can decompose it into
1396 /// insertions into the vector. See the example in the comment for
1397 /// OptimizeIntegerToVectorInsertions for the pattern this handles.
1398 /// The type of V is always a non-zero multiple of VecEltTy's size.
1400 /// This returns false if the pattern can't be matched or true if it can,
1401 /// filling in Elements with the elements found here.
1402 static bool CollectInsertionElements(Value *V, unsigned ElementIndex,
1403 SmallVectorImpl<Value*> &Elements,
1404 const Type *VecEltTy) {
1405 // Undef values never contribute useful bits to the result.
1406 if (isa<UndefValue>(V)) return true;
1408 // If we got down to a value of the right type, we win, try inserting into the
1410 if (V->getType() == VecEltTy) {
1411 // Inserting null doesn't actually insert any elements.
1412 if (Constant *C = dyn_cast<Constant>(V))
1413 if (C->isNullValue())
1416 // Fail if multiple elements are inserted into this slot.
1417 if (ElementIndex >= Elements.size() || Elements[ElementIndex] != 0)
1420 Elements[ElementIndex] = V;
1424 if (Constant *C = dyn_cast<Constant>(V)) {
1425 // Figure out the # elements this provides, and bitcast it or slice it up
1427 unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(),
1429 // If the constant is the size of a vector element, we just need to bitcast
1430 // it to the right type so it gets properly inserted.
1432 return CollectInsertionElements(ConstantExpr::getBitCast(C, VecEltTy),
1433 ElementIndex, Elements, VecEltTy);
1435 // Okay, this is a constant that covers multiple elements. Slice it up into
1436 // pieces and insert each element-sized piece into the vector.
1437 if (!isa<IntegerType>(C->getType()))
1438 C = ConstantExpr::getBitCast(C, IntegerType::get(V->getContext(),
1439 C->getType()->getPrimitiveSizeInBits()));
1440 unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits();
1441 const Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize);
1443 for (unsigned i = 0; i != NumElts; ++i) {
1444 Constant *Piece = ConstantExpr::getLShr(C, ConstantInt::get(C->getType(),
1446 Piece = ConstantExpr::getTrunc(Piece, ElementIntTy);
1447 if (!CollectInsertionElements(Piece, ElementIndex+i, Elements, VecEltTy))
1453 if (!V->hasOneUse()) return false;
1455 Instruction *I = dyn_cast<Instruction>(V);
1456 if (I == 0) return false;
1457 switch (I->getOpcode()) {
1458 default: return false; // Unhandled case.
1459 case Instruction::BitCast:
1460 return CollectInsertionElements(I->getOperand(0), ElementIndex,
1461 Elements, VecEltTy);
1462 case Instruction::ZExt:
1463 if (!isMultipleOfTypeSize(
1464 I->getOperand(0)->getType()->getPrimitiveSizeInBits(),
1467 return CollectInsertionElements(I->getOperand(0), ElementIndex,
1468 Elements, VecEltTy);
1469 case Instruction::Or:
1470 return CollectInsertionElements(I->getOperand(0), ElementIndex,
1471 Elements, VecEltTy) &&
1472 CollectInsertionElements(I->getOperand(1), ElementIndex,
1473 Elements, VecEltTy);
1474 case Instruction::Shl: {
1475 // Must be shifting by a constant that is a multiple of the element size.
1476 ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1));
1477 if (CI == 0) return false;
1478 if (!isMultipleOfTypeSize(CI->getZExtValue(), VecEltTy)) return false;
1479 unsigned IndexShift = getTypeSizeIndex(CI->getZExtValue(), VecEltTy);
1481 return CollectInsertionElements(I->getOperand(0), ElementIndex+IndexShift,
1482 Elements, VecEltTy);
1489 /// OptimizeIntegerToVectorInsertions - If the input is an 'or' instruction, we
1490 /// may be doing shifts and ors to assemble the elements of the vector manually.
1491 /// Try to rip the code out and replace it with insertelements. This is to
1492 /// optimize code like this:
1494 /// %tmp37 = bitcast float %inc to i32
1495 /// %tmp38 = zext i32 %tmp37 to i64
1496 /// %tmp31 = bitcast float %inc5 to i32
1497 /// %tmp32 = zext i32 %tmp31 to i64
1498 /// %tmp33 = shl i64 %tmp32, 32
1499 /// %ins35 = or i64 %tmp33, %tmp38
1500 /// %tmp43 = bitcast i64 %ins35 to <2 x float>
1502 /// Into two insertelements that do "buildvector{%inc, %inc5}".
1503 static Value *OptimizeIntegerToVectorInsertions(BitCastInst &CI,
1505 const VectorType *DestVecTy = cast<VectorType>(CI.getType());
1506 Value *IntInput = CI.getOperand(0);
1508 SmallVector<Value*, 8> Elements(DestVecTy->getNumElements());
1509 if (!CollectInsertionElements(IntInput, 0, Elements,
1510 DestVecTy->getElementType()))
1513 // If we succeeded, we know that all of the element are specified by Elements
1514 // or are zero if Elements has a null entry. Recast this as a set of
1516 Value *Result = Constant::getNullValue(CI.getType());
1517 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
1518 if (Elements[i] == 0) continue; // Unset element.
1520 Result = IC.Builder->CreateInsertElement(Result, Elements[i],
1521 IC.Builder->getInt32(i));
1528 /// OptimizeIntToFloatBitCast - See if we can optimize an integer->float/double
1529 /// bitcast. The various long double bitcasts can't get in here.
1530 static Instruction *OptimizeIntToFloatBitCast(BitCastInst &CI,InstCombiner &IC){
1531 Value *Src = CI.getOperand(0);
1532 const Type *DestTy = CI.getType();
1534 // If this is a bitcast from int to float, check to see if the int is an
1535 // extraction from a vector.
1536 Value *VecInput = 0;
1537 // bitcast(trunc(bitcast(somevector)))
1538 if (match(Src, m_Trunc(m_BitCast(m_Value(VecInput)))) &&
1539 isa<VectorType>(VecInput->getType())) {
1540 const VectorType *VecTy = cast<VectorType>(VecInput->getType());
1541 unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
1543 if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0) {
1544 // If the element type of the vector doesn't match the result type,
1545 // bitcast it to be a vector type we can extract from.
1546 if (VecTy->getElementType() != DestTy) {
1547 VecTy = VectorType::get(DestTy,
1548 VecTy->getPrimitiveSizeInBits() / DestWidth);
1549 VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
1552 return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(0));
1556 // bitcast(trunc(lshr(bitcast(somevector), cst))
1557 ConstantInt *ShAmt = 0;
1558 if (match(Src, m_Trunc(m_LShr(m_BitCast(m_Value(VecInput)),
1559 m_ConstantInt(ShAmt)))) &&
1560 isa<VectorType>(VecInput->getType())) {
1561 const VectorType *VecTy = cast<VectorType>(VecInput->getType());
1562 unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
1563 if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0 &&
1564 ShAmt->getZExtValue() % DestWidth == 0) {
1565 // If the element type of the vector doesn't match the result type,
1566 // bitcast it to be a vector type we can extract from.
1567 if (VecTy->getElementType() != DestTy) {
1568 VecTy = VectorType::get(DestTy,
1569 VecTy->getPrimitiveSizeInBits() / DestWidth);
1570 VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
1573 unsigned Elt = ShAmt->getZExtValue() / DestWidth;
1574 return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
1580 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
1581 // If the operands are integer typed then apply the integer transforms,
1582 // otherwise just apply the common ones.
1583 Value *Src = CI.getOperand(0);
1584 const Type *SrcTy = Src->getType();
1585 const Type *DestTy = CI.getType();
1587 // Get rid of casts from one type to the same type. These are useless and can
1588 // be replaced by the operand.
1589 if (DestTy == Src->getType())
1590 return ReplaceInstUsesWith(CI, Src);
1592 if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
1593 const PointerType *SrcPTy = cast<PointerType>(SrcTy);
1594 const Type *DstElTy = DstPTy->getElementType();
1595 const Type *SrcElTy = SrcPTy->getElementType();
1597 // If the address spaces don't match, don't eliminate the bitcast, which is
1598 // required for changing types.
1599 if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
1602 // If we are casting a alloca to a pointer to a type of the same
1603 // size, rewrite the allocation instruction to allocate the "right" type.
1604 // There is no need to modify malloc calls because it is their bitcast that
1605 // needs to be cleaned up.
1606 if (AllocaInst *AI = dyn_cast<AllocaInst>(Src))
1607 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
1610 // If the source and destination are pointers, and this cast is equivalent
1611 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
1612 // This can enhance SROA and other transforms that want type-safe pointers.
1613 Constant *ZeroUInt =
1614 Constant::getNullValue(Type::getInt32Ty(CI.getContext()));
1615 unsigned NumZeros = 0;
1616 while (SrcElTy != DstElTy &&
1617 isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
1618 SrcElTy->getNumContainedTypes() /* not "{}" */) {
1619 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
1623 // If we found a path from the src to dest, create the getelementptr now.
1624 if (SrcElTy == DstElTy) {
1625 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
1626 return GetElementPtrInst::CreateInBounds(Src, Idxs.begin(), Idxs.end(),"",
1627 ((Instruction*)NULL));
1631 // Try to optimize int -> float bitcasts.
1632 if ((DestTy->isFloatTy() || DestTy->isDoubleTy()) && isa<IntegerType>(SrcTy))
1633 if (Instruction *I = OptimizeIntToFloatBitCast(CI, *this))
1636 if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
1637 if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) {
1638 Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
1639 return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
1640 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
1641 // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
1644 if (isa<IntegerType>(SrcTy)) {
1645 // If this is a cast from an integer to vector, check to see if the input
1646 // is a trunc or zext of a bitcast from vector. If so, we can replace all
1647 // the casts with a shuffle and (potentially) a bitcast.
1648 if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) {
1649 CastInst *SrcCast = cast<CastInst>(Src);
1650 if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0)))
1651 if (isa<VectorType>(BCIn->getOperand(0)->getType()))
1652 if (Instruction *I = OptimizeVectorResize(BCIn->getOperand(0),
1653 cast<VectorType>(DestTy), *this))
1657 // If the input is an 'or' instruction, we may be doing shifts and ors to
1658 // assemble the elements of the vector manually. Try to rip the code out
1659 // and replace it with insertelements.
1660 if (Value *V = OptimizeIntegerToVectorInsertions(CI, *this))
1661 return ReplaceInstUsesWith(CI, V);
1665 if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
1666 if (SrcVTy->getNumElements() == 1 && !DestTy->isVectorTy()) {
1668 Builder->CreateExtractElement(Src,
1669 Constant::getNullValue(Type::getInt32Ty(CI.getContext())));
1670 return CastInst::Create(Instruction::BitCast, Elem, DestTy);
1674 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
1675 // Okay, we have (bitcast (shuffle ..)). Check to see if this is
1676 // a bitcast to a vector with the same # elts.
1677 if (SVI->hasOneUse() && DestTy->isVectorTy() &&
1678 cast<VectorType>(DestTy)->getNumElements() ==
1679 SVI->getType()->getNumElements() &&
1680 SVI->getType()->getNumElements() ==
1681 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
1683 // If either of the operands is a cast from CI.getType(), then
1684 // evaluating the shuffle in the casted destination's type will allow
1685 // us to eliminate at least one cast.
1686 if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
1687 Tmp->getOperand(0)->getType() == DestTy) ||
1688 ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
1689 Tmp->getOperand(0)->getType() == DestTy)) {
1690 Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
1691 Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
1692 // Return a new shuffle vector. Use the same element ID's, as we
1693 // know the vector types match #elts.
1694 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
1699 if (SrcTy->isPointerTy())
1700 return commonPointerCastTransforms(CI);
1701 return commonCastTransforms(CI);