1 //===-- ConstantFolding.cpp - Fold instructions into constants ------------===//
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 defines routines for folding instructions into constants.
12 // Also, to supplement the basic VMCore ConstantExpr simplifications,
13 // this file defines some additional folding routines that can make use of
14 // TargetData information. These functions cannot go in VMCore due to library
17 //===----------------------------------------------------------------------===//
19 #include "llvm/Analysis/ConstantFolding.h"
20 #include "llvm/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/Function.h"
23 #include "llvm/GlobalVariable.h"
24 #include "llvm/Instructions.h"
25 #include "llvm/Intrinsics.h"
26 #include "llvm/Analysis/ValueTracking.h"
27 #include "llvm/Target/TargetData.h"
28 #include "llvm/ADT/SmallVector.h"
29 #include "llvm/ADT/StringMap.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/GetElementPtrTypeIterator.h"
32 #include "llvm/Support/MathExtras.h"
33 #include "llvm/Support/FEnv.h"
38 //===----------------------------------------------------------------------===//
39 // Constant Folding internal helper functions
40 //===----------------------------------------------------------------------===//
42 /// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
43 /// TargetData. This always returns a non-null constant, but it may be a
44 /// ConstantExpr if unfoldable.
45 static Constant *FoldBitCast(Constant *C, const Type *DestTy,
46 const TargetData &TD) {
48 // This only handles casts to vectors currently.
49 const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
51 return ConstantExpr::getBitCast(C, DestTy);
53 // If this is a scalar -> vector cast, convert the input into a <1 x scalar>
54 // vector so the code below can handle it uniformly.
55 if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) {
56 Constant *Ops = C; // don't take the address of C!
57 return FoldBitCast(ConstantVector::get(&Ops, 1), DestTy, TD);
60 // If this is a bitcast from constant vector -> vector, fold it.
61 ConstantVector *CV = dyn_cast<ConstantVector>(C);
63 return ConstantExpr::getBitCast(C, DestTy);
65 // If the element types match, VMCore can fold it.
66 unsigned NumDstElt = DestVTy->getNumElements();
67 unsigned NumSrcElt = CV->getNumOperands();
68 if (NumDstElt == NumSrcElt)
69 return ConstantExpr::getBitCast(C, DestTy);
71 const Type *SrcEltTy = CV->getType()->getElementType();
72 const Type *DstEltTy = DestVTy->getElementType();
74 // Otherwise, we're changing the number of elements in a vector, which
75 // requires endianness information to do the right thing. For example,
76 // bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
77 // folds to (little endian):
78 // <4 x i32> <i32 0, i32 0, i32 1, i32 0>
79 // and to (big endian):
80 // <4 x i32> <i32 0, i32 0, i32 0, i32 1>
82 // First thing is first. We only want to think about integer here, so if
83 // we have something in FP form, recast it as integer.
84 if (DstEltTy->isFloatingPointTy()) {
85 // Fold to an vector of integers with same size as our FP type.
86 unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
87 const Type *DestIVTy =
88 VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt);
89 // Recursively handle this integer conversion, if possible.
90 C = FoldBitCast(C, DestIVTy, TD);
91 if (!C) return ConstantExpr::getBitCast(C, DestTy);
93 // Finally, VMCore can handle this now that #elts line up.
94 return ConstantExpr::getBitCast(C, DestTy);
97 // Okay, we know the destination is integer, if the input is FP, convert
98 // it to integer first.
99 if (SrcEltTy->isFloatingPointTy()) {
100 unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
101 const Type *SrcIVTy =
102 VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
103 // Ask VMCore to do the conversion now that #elts line up.
104 C = ConstantExpr::getBitCast(C, SrcIVTy);
105 CV = dyn_cast<ConstantVector>(C);
106 if (!CV) // If VMCore wasn't able to fold it, bail out.
110 // Now we know that the input and output vectors are both integer vectors
111 // of the same size, and that their #elements is not the same. Do the
112 // conversion here, which depends on whether the input or output has
114 bool isLittleEndian = TD.isLittleEndian();
116 SmallVector<Constant*, 32> Result;
117 if (NumDstElt < NumSrcElt) {
118 // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
119 Constant *Zero = Constant::getNullValue(DstEltTy);
120 unsigned Ratio = NumSrcElt/NumDstElt;
121 unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
123 for (unsigned i = 0; i != NumDstElt; ++i) {
124 // Build each element of the result.
125 Constant *Elt = Zero;
126 unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
127 for (unsigned j = 0; j != Ratio; ++j) {
128 Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
129 if (!Src) // Reject constantexpr elements.
130 return ConstantExpr::getBitCast(C, DestTy);
132 // Zero extend the element to the right size.
133 Src = ConstantExpr::getZExt(Src, Elt->getType());
135 // Shift it to the right place, depending on endianness.
136 Src = ConstantExpr::getShl(Src,
137 ConstantInt::get(Src->getType(), ShiftAmt));
138 ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
141 Elt = ConstantExpr::getOr(Elt, Src);
143 Result.push_back(Elt);
146 // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
147 unsigned Ratio = NumDstElt/NumSrcElt;
148 unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
150 // Loop over each source value, expanding into multiple results.
151 for (unsigned i = 0; i != NumSrcElt; ++i) {
152 Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
153 if (!Src) // Reject constantexpr elements.
154 return ConstantExpr::getBitCast(C, DestTy);
156 unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
157 for (unsigned j = 0; j != Ratio; ++j) {
158 // Shift the piece of the value into the right place, depending on
160 Constant *Elt = ConstantExpr::getLShr(Src,
161 ConstantInt::get(Src->getType(), ShiftAmt));
162 ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
164 // Truncate and remember this piece.
165 Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
170 return ConstantVector::get(Result.data(), Result.size());
174 /// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
175 /// from a global, return the global and the constant. Because of
176 /// constantexprs, this function is recursive.
177 static bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
178 int64_t &Offset, const TargetData &TD) {
179 // Trivial case, constant is the global.
180 if ((GV = dyn_cast<GlobalValue>(C))) {
185 // Otherwise, if this isn't a constant expr, bail out.
186 ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
187 if (!CE) return false;
189 // Look through ptr->int and ptr->ptr casts.
190 if (CE->getOpcode() == Instruction::PtrToInt ||
191 CE->getOpcode() == Instruction::BitCast)
192 return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD);
194 // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
195 if (CE->getOpcode() == Instruction::GetElementPtr) {
196 // Cannot compute this if the element type of the pointer is missing size
198 if (!cast<PointerType>(CE->getOperand(0)->getType())
199 ->getElementType()->isSized())
202 // If the base isn't a global+constant, we aren't either.
203 if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD))
206 // Otherwise, add any offset that our operands provide.
207 gep_type_iterator GTI = gep_type_begin(CE);
208 for (User::const_op_iterator i = CE->op_begin() + 1, e = CE->op_end();
209 i != e; ++i, ++GTI) {
210 ConstantInt *CI = dyn_cast<ConstantInt>(*i);
211 if (!CI) return false; // Index isn't a simple constant?
212 if (CI->isZero()) continue; // Not adding anything.
214 if (const StructType *ST = dyn_cast<StructType>(*GTI)) {
216 Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue());
218 const SequentialType *SQT = cast<SequentialType>(*GTI);
219 Offset += TD.getTypeAllocSize(SQT->getElementType())*CI->getSExtValue();
228 /// ReadDataFromGlobal - Recursive helper to read bits out of global. C is the
229 /// constant being copied out of. ByteOffset is an offset into C. CurPtr is the
230 /// pointer to copy results into and BytesLeft is the number of bytes left in
231 /// the CurPtr buffer. TD is the target data.
232 static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
233 unsigned char *CurPtr, unsigned BytesLeft,
234 const TargetData &TD) {
235 assert(ByteOffset <= TD.getTypeAllocSize(C->getType()) &&
236 "Out of range access");
238 // If this element is zero or undefined, we can just return since *CurPtr is
240 if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C))
243 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
244 if (CI->getBitWidth() > 64 ||
245 (CI->getBitWidth() & 7) != 0)
248 uint64_t Val = CI->getZExtValue();
249 unsigned IntBytes = unsigned(CI->getBitWidth()/8);
251 for (unsigned i = 0; i != BytesLeft && ByteOffset != IntBytes; ++i) {
252 CurPtr[i] = (unsigned char)(Val >> (ByteOffset * 8));
258 if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
259 if (CFP->getType()->isDoubleTy()) {
260 C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), TD);
261 return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
263 if (CFP->getType()->isFloatTy()){
264 C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD);
265 return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
270 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
271 const StructLayout *SL = TD.getStructLayout(CS->getType());
272 unsigned Index = SL->getElementContainingOffset(ByteOffset);
273 uint64_t CurEltOffset = SL->getElementOffset(Index);
274 ByteOffset -= CurEltOffset;
277 // If the element access is to the element itself and not to tail padding,
278 // read the bytes from the element.
279 uint64_t EltSize = TD.getTypeAllocSize(CS->getOperand(Index)->getType());
281 if (ByteOffset < EltSize &&
282 !ReadDataFromGlobal(CS->getOperand(Index), ByteOffset, CurPtr,
288 // Check to see if we read from the last struct element, if so we're done.
289 if (Index == CS->getType()->getNumElements())
292 // If we read all of the bytes we needed from this element we're done.
293 uint64_t NextEltOffset = SL->getElementOffset(Index);
295 if (BytesLeft <= NextEltOffset-CurEltOffset-ByteOffset)
298 // Move to the next element of the struct.
299 CurPtr += NextEltOffset-CurEltOffset-ByteOffset;
300 BytesLeft -= NextEltOffset-CurEltOffset-ByteOffset;
302 CurEltOffset = NextEltOffset;
307 if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
308 uint64_t EltSize = TD.getTypeAllocSize(CA->getType()->getElementType());
309 uint64_t Index = ByteOffset / EltSize;
310 uint64_t Offset = ByteOffset - Index * EltSize;
311 for (; Index != CA->getType()->getNumElements(); ++Index) {
312 if (!ReadDataFromGlobal(CA->getOperand(Index), Offset, CurPtr,
315 if (EltSize >= BytesLeft)
319 BytesLeft -= EltSize;
325 if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) {
326 uint64_t EltSize = TD.getTypeAllocSize(CV->getType()->getElementType());
327 uint64_t Index = ByteOffset / EltSize;
328 uint64_t Offset = ByteOffset - Index * EltSize;
329 for (; Index != CV->getType()->getNumElements(); ++Index) {
330 if (!ReadDataFromGlobal(CV->getOperand(Index), Offset, CurPtr,
333 if (EltSize >= BytesLeft)
337 BytesLeft -= EltSize;
343 // Otherwise, unknown initializer type.
347 static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
348 const TargetData &TD) {
349 const Type *LoadTy = cast<PointerType>(C->getType())->getElementType();
350 const IntegerType *IntType = dyn_cast<IntegerType>(LoadTy);
352 // If this isn't an integer load we can't fold it directly.
354 // If this is a float/double load, we can try folding it as an int32/64 load
355 // and then bitcast the result. This can be useful for union cases. Note
356 // that address spaces don't matter here since we're not going to result in
357 // an actual new load.
359 if (LoadTy->isFloatTy())
360 MapTy = Type::getInt32PtrTy(C->getContext());
361 else if (LoadTy->isDoubleTy())
362 MapTy = Type::getInt64PtrTy(C->getContext());
363 else if (LoadTy->isVectorTy()) {
364 MapTy = IntegerType::get(C->getContext(),
365 TD.getTypeAllocSizeInBits(LoadTy));
366 MapTy = PointerType::getUnqual(MapTy);
370 C = FoldBitCast(C, MapTy, TD);
371 if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD))
372 return FoldBitCast(Res, LoadTy, TD);
376 unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
377 if (BytesLoaded > 32 || BytesLoaded == 0) return 0;
381 if (!IsConstantOffsetFromGlobal(C, GVal, Offset, TD))
384 GlobalVariable *GV = dyn_cast<GlobalVariable>(GVal);
385 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
386 !GV->getInitializer()->getType()->isSized())
389 // If we're loading off the beginning of the global, some bytes may be valid,
390 // but we don't try to handle this.
391 if (Offset < 0) return 0;
393 // If we're not accessing anything in this constant, the result is undefined.
394 if (uint64_t(Offset) >= TD.getTypeAllocSize(GV->getInitializer()->getType()))
395 return UndefValue::get(IntType);
397 unsigned char RawBytes[32] = {0};
398 if (!ReadDataFromGlobal(GV->getInitializer(), Offset, RawBytes,
402 APInt ResultVal = APInt(IntType->getBitWidth(), RawBytes[BytesLoaded-1]);
403 for (unsigned i = 1; i != BytesLoaded; ++i) {
405 ResultVal |= RawBytes[BytesLoaded-1-i];
408 return ConstantInt::get(IntType->getContext(), ResultVal);
411 /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
412 /// produce if it is constant and determinable. If this is not determinable,
414 Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
415 const TargetData *TD) {
416 // First, try the easy cases:
417 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
418 if (GV->isConstant() && GV->hasDefinitiveInitializer())
419 return GV->getInitializer();
421 // If the loaded value isn't a constant expr, we can't handle it.
422 ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
425 if (CE->getOpcode() == Instruction::GetElementPtr) {
426 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
427 if (GV->isConstant() && GV->hasDefinitiveInitializer())
429 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
433 // Instead of loading constant c string, use corresponding integer value
434 // directly if string length is small enough.
436 if (TD && GetConstantStringInfo(CE, Str) && !Str.empty()) {
437 unsigned StrLen = Str.length();
438 const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
439 unsigned NumBits = Ty->getPrimitiveSizeInBits();
440 // Replace load with immediate integer if the result is an integer or fp
442 if ((NumBits >> 3) == StrLen + 1 && (NumBits & 7) == 0 &&
443 (isa<IntegerType>(Ty) || Ty->isFloatingPointTy())) {
444 APInt StrVal(NumBits, 0);
445 APInt SingleChar(NumBits, 0);
446 if (TD->isLittleEndian()) {
447 for (signed i = StrLen-1; i >= 0; i--) {
448 SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
449 StrVal = (StrVal << 8) | SingleChar;
452 for (unsigned i = 0; i < StrLen; i++) {
453 SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
454 StrVal = (StrVal << 8) | SingleChar;
456 // Append NULL at the end.
458 StrVal = (StrVal << 8) | SingleChar;
461 Constant *Res = ConstantInt::get(CE->getContext(), StrVal);
462 if (Ty->isFloatingPointTy())
463 Res = ConstantExpr::getBitCast(Res, Ty);
468 // If this load comes from anywhere in a constant global, and if the global
469 // is all undef or zero, we know what it loads.
470 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(CE))){
471 if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
472 const Type *ResTy = cast<PointerType>(C->getType())->getElementType();
473 if (GV->getInitializer()->isNullValue())
474 return Constant::getNullValue(ResTy);
475 if (isa<UndefValue>(GV->getInitializer()))
476 return UndefValue::get(ResTy);
480 // Try hard to fold loads from bitcasted strange and non-type-safe things. We
481 // currently don't do any of this for big endian systems. It can be
482 // generalized in the future if someone is interested.
483 if (TD && TD->isLittleEndian())
484 return FoldReinterpretLoadFromConstPtr(CE, *TD);
488 static Constant *ConstantFoldLoadInst(const LoadInst *LI, const TargetData *TD){
489 if (LI->isVolatile()) return 0;
491 if (Constant *C = dyn_cast<Constant>(LI->getOperand(0)))
492 return ConstantFoldLoadFromConstPtr(C, TD);
497 /// SymbolicallyEvaluateBinop - One of Op0/Op1 is a constant expression.
498 /// Attempt to symbolically evaluate the result of a binary operator merging
499 /// these together. If target data info is available, it is provided as TD,
500 /// otherwise TD is null.
501 static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0,
502 Constant *Op1, const TargetData *TD){
505 // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
506 // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute
510 // If the constant expr is something like &A[123] - &A[4].f, fold this into a
511 // constant. This happens frequently when iterating over a global array.
512 if (Opc == Instruction::Sub && TD) {
513 GlobalValue *GV1, *GV2;
514 int64_t Offs1, Offs2;
516 if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, *TD))
517 if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, *TD) &&
519 // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
520 return ConstantInt::get(Op0->getType(), Offs1-Offs2);
527 /// CastGEPIndices - If array indices are not pointer-sized integers,
528 /// explicitly cast them so that they aren't implicitly casted by the
530 static Constant *CastGEPIndices(Constant *const *Ops, unsigned NumOps,
531 const Type *ResultTy,
532 const TargetData *TD) {
534 const Type *IntPtrTy = TD->getIntPtrType(ResultTy->getContext());
537 SmallVector<Constant*, 32> NewIdxs;
538 for (unsigned i = 1; i != NumOps; ++i) {
540 !isa<StructType>(GetElementPtrInst::getIndexedType(Ops[0]->getType(),
541 reinterpret_cast<Value *const *>(Ops+1),
543 Ops[i]->getType() != IntPtrTy) {
545 NewIdxs.push_back(ConstantExpr::getCast(CastInst::getCastOpcode(Ops[i],
551 NewIdxs.push_back(Ops[i]);
556 ConstantExpr::getGetElementPtr(Ops[0], &NewIdxs[0], NewIdxs.size());
557 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
558 if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
563 /// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
564 /// constant expression, do so.
565 static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
566 const Type *ResultTy,
567 const TargetData *TD) {
568 Constant *Ptr = Ops[0];
569 if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()->isSized())
573 TD->getTypeSizeInBits(TD->getIntPtrType(Ptr->getContext()));
575 // If this is a constant expr gep that is effectively computing an
576 // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12'
577 for (unsigned i = 1; i != NumOps; ++i)
578 if (!isa<ConstantInt>(Ops[i])) {
580 // If this is "gep i8* Ptr, (sub 0, V)", fold this as:
581 // "inttoptr (sub (ptrtoint Ptr), V)"
583 cast<PointerType>(ResultTy)->getElementType()->isIntegerTy(8)) {
584 ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[1]);
585 if (CE && CE->getOpcode() == Instruction::Sub &&
586 isa<ConstantInt>(CE->getOperand(0)) &&
587 cast<ConstantInt>(CE->getOperand(0))->isZero()) {
588 Constant *Res = ConstantExpr::getPtrToInt(Ptr, CE->getType());
589 Res = ConstantExpr::getSub(Res, CE->getOperand(1));
590 Res = ConstantExpr::getIntToPtr(Res, ResultTy);
591 if (ConstantExpr *ResCE = dyn_cast<ConstantExpr>(Res))
592 Res = ConstantFoldConstantExpression(ResCE, TD);
599 APInt Offset = APInt(BitWidth,
600 TD->getIndexedOffset(Ptr->getType(),
601 (Value**)Ops+1, NumOps-1));
602 Ptr = cast<Constant>(Ptr->stripPointerCasts());
604 // If this is a GEP of a GEP, fold it all into a single GEP.
605 while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
606 SmallVector<Value *, 4> NestedOps(GEP->op_begin()+1, GEP->op_end());
608 // Do not try the incorporate the sub-GEP if some index is not a number.
609 bool AllConstantInt = true;
610 for (unsigned i = 0, e = NestedOps.size(); i != e; ++i)
611 if (!isa<ConstantInt>(NestedOps[i])) {
612 AllConstantInt = false;
618 Ptr = cast<Constant>(GEP->getOperand(0));
619 Offset += APInt(BitWidth,
620 TD->getIndexedOffset(Ptr->getType(),
621 (Value**)NestedOps.data(),
623 Ptr = cast<Constant>(Ptr->stripPointerCasts());
626 // If the base value for this address is a literal integer value, fold the
627 // getelementptr to the resulting integer value casted to the pointer type.
628 APInt BasePtr(BitWidth, 0);
629 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
630 if (CE->getOpcode() == Instruction::IntToPtr)
631 if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
632 BasePtr = Base->getValue().zextOrTrunc(BitWidth);
633 if (Ptr->isNullValue() || BasePtr != 0) {
634 Constant *C = ConstantInt::get(Ptr->getContext(), Offset+BasePtr);
635 return ConstantExpr::getIntToPtr(C, ResultTy);
638 // Otherwise form a regular getelementptr. Recompute the indices so that
639 // we eliminate over-indexing of the notional static type array bounds.
640 // This makes it easy to determine if the getelementptr is "inbounds".
641 // Also, this helps GlobalOpt do SROA on GlobalVariables.
642 const Type *Ty = Ptr->getType();
643 SmallVector<Constant*, 32> NewIdxs;
645 if (const SequentialType *ATy = dyn_cast<SequentialType>(Ty)) {
646 if (ATy->isPointerTy()) {
647 // The only pointer indexing we'll do is on the first index of the GEP.
648 if (!NewIdxs.empty())
651 // Only handle pointers to sized types, not pointers to functions.
652 if (!ATy->getElementType()->isSized())
656 // Determine which element of the array the offset points into.
657 APInt ElemSize(BitWidth, TD->getTypeAllocSize(ATy->getElementType()));
658 const IntegerType *IntPtrTy = TD->getIntPtrType(Ty->getContext());
660 // The element size is 0. This may be [0 x Ty]*, so just use a zero
661 // index for this level and proceed to the next level to see if it can
662 // accommodate the offset.
663 NewIdxs.push_back(ConstantInt::get(IntPtrTy, 0));
665 // The element size is non-zero divide the offset by the element
666 // size (rounding down), to compute the index at this level.
667 APInt NewIdx = Offset.udiv(ElemSize);
668 Offset -= NewIdx * ElemSize;
669 NewIdxs.push_back(ConstantInt::get(IntPtrTy, NewIdx));
671 Ty = ATy->getElementType();
672 } else if (const StructType *STy = dyn_cast<StructType>(Ty)) {
673 // Determine which field of the struct the offset points into. The
674 // getZExtValue is at least as safe as the StructLayout API because we
675 // know the offset is within the struct at this point.
676 const StructLayout &SL = *TD->getStructLayout(STy);
677 unsigned ElIdx = SL.getElementContainingOffset(Offset.getZExtValue());
678 NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
680 Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx));
681 Ty = STy->getTypeAtIndex(ElIdx);
683 // We've reached some non-indexable type.
686 } while (Ty != cast<PointerType>(ResultTy)->getElementType());
688 // If we haven't used up the entire offset by descending the static
689 // type, then the offset is pointing into the middle of an indivisible
690 // member, so we can't simplify it.
696 ConstantExpr::getGetElementPtr(Ptr, &NewIdxs[0], NewIdxs.size());
697 assert(cast<PointerType>(C->getType())->getElementType() == Ty &&
698 "Computed GetElementPtr has unexpected type!");
700 // If we ended up indexing a member with a type that doesn't match
701 // the type of what the original indices indexed, add a cast.
702 if (Ty != cast<PointerType>(ResultTy)->getElementType())
703 C = FoldBitCast(C, ResultTy, *TD);
710 //===----------------------------------------------------------------------===//
711 // Constant Folding public APIs
712 //===----------------------------------------------------------------------===//
714 /// ConstantFoldInstruction - Try to constant fold the specified instruction.
715 /// If successful, the constant result is returned, if not, null is returned.
716 /// Note that this fails if not all of the operands are constant. Otherwise,
717 /// this function can only fail when attempting to fold instructions like loads
718 /// and stores, which have no constant expression form.
719 Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) {
720 // Handle PHI nodes quickly here...
721 if (PHINode *PN = dyn_cast<PHINode>(I)) {
722 Constant *CommonValue = 0;
724 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
725 Value *Incoming = PN->getIncomingValue(i);
726 // If the incoming value is undef then skip it. Note that while we could
727 // skip the value if it is equal to the phi node itself we choose not to
728 // because that would break the rule that constant folding only applies if
729 // all operands are constants.
730 if (isa<UndefValue>(Incoming))
732 // If the incoming value is not a constant, or is a different constant to
733 // the one we saw previously, then give up.
734 Constant *C = dyn_cast<Constant>(Incoming);
735 if (!C || (CommonValue && C != CommonValue))
740 // If we reach here, all incoming values are the same constant or undef.
741 return CommonValue ? CommonValue : UndefValue::get(PN->getType());
744 // Scan the operand list, checking to see if they are all constants, if so,
745 // hand off to ConstantFoldInstOperands.
746 SmallVector<Constant*, 8> Ops;
747 for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
748 if (Constant *Op = dyn_cast<Constant>(*i))
751 return 0; // All operands not constant!
753 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
754 return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
757 if (const LoadInst *LI = dyn_cast<LoadInst>(I))
758 return ConstantFoldLoadInst(LI, TD);
760 if (InsertValueInst *IVI = dyn_cast<InsertValueInst>(I))
761 return ConstantExpr::getInsertValue(
762 cast<Constant>(IVI->getAggregateOperand()),
763 cast<Constant>(IVI->getInsertedValueOperand()),
764 IVI->idx_begin(), IVI->getNumIndices());
766 if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I))
767 return ConstantExpr::getExtractValue(
768 cast<Constant>(EVI->getAggregateOperand()),
769 EVI->idx_begin(), EVI->getNumIndices());
771 return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
772 Ops.data(), Ops.size(), TD);
775 /// ConstantFoldConstantExpression - Attempt to fold the constant expression
776 /// using the specified TargetData. If successful, the constant result is
777 /// result is returned, if not, null is returned.
778 Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
779 const TargetData *TD) {
780 SmallVector<Constant*, 8> Ops;
781 for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end();
783 Constant *NewC = cast<Constant>(*i);
784 // Recursively fold the ConstantExpr's operands.
785 if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC))
786 NewC = ConstantFoldConstantExpression(NewCE, TD);
791 return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
793 return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(),
794 Ops.data(), Ops.size(), TD);
797 /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
798 /// specified opcode and operands. If successful, the constant result is
799 /// returned, if not, null is returned. Note that this function can fail when
800 /// attempting to fold instructions like loads and stores, which have no
801 /// constant expression form.
803 /// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
804 /// information, due to only being passed an opcode and operands. Constant
805 /// folding using this function strips this information.
807 Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
808 Constant* const* Ops, unsigned NumOps,
809 const TargetData *TD) {
810 // Handle easy binops first.
811 if (Instruction::isBinaryOp(Opcode)) {
812 if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1]))
813 if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD))
816 return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
821 case Instruction::ICmp:
822 case Instruction::FCmp: assert(0 && "Invalid for compares");
823 case Instruction::Call:
824 if (Function *F = dyn_cast<Function>(Ops[NumOps - 1]))
825 if (canConstantFoldCallTo(F))
826 return ConstantFoldCall(F, Ops, NumOps - 1);
828 case Instruction::PtrToInt:
829 // If the input is a inttoptr, eliminate the pair. This requires knowing
830 // the width of a pointer, so it can't be done in ConstantExpr::getCast.
831 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
832 if (TD && CE->getOpcode() == Instruction::IntToPtr) {
833 Constant *Input = CE->getOperand(0);
834 unsigned InWidth = Input->getType()->getScalarSizeInBits();
835 if (TD->getPointerSizeInBits() < InWidth) {
837 ConstantInt::get(CE->getContext(), APInt::getLowBitsSet(InWidth,
838 TD->getPointerSizeInBits()));
839 Input = ConstantExpr::getAnd(Input, Mask);
841 // Do a zext or trunc to get to the dest size.
842 return ConstantExpr::getIntegerCast(Input, DestTy, false);
845 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
846 case Instruction::IntToPtr:
847 // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
848 // the int size is >= the ptr size. This requires knowing the width of a
849 // pointer, so it can't be done in ConstantExpr::getCast.
850 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0]))
852 TD->getPointerSizeInBits() <= CE->getType()->getScalarSizeInBits() &&
853 CE->getOpcode() == Instruction::PtrToInt)
854 return FoldBitCast(CE->getOperand(0), DestTy, *TD);
856 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
857 case Instruction::Trunc:
858 case Instruction::ZExt:
859 case Instruction::SExt:
860 case Instruction::FPTrunc:
861 case Instruction::FPExt:
862 case Instruction::UIToFP:
863 case Instruction::SIToFP:
864 case Instruction::FPToUI:
865 case Instruction::FPToSI:
866 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
867 case Instruction::BitCast:
869 return FoldBitCast(Ops[0], DestTy, *TD);
870 return ConstantExpr::getBitCast(Ops[0], DestTy);
871 case Instruction::Select:
872 return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
873 case Instruction::ExtractElement:
874 return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
875 case Instruction::InsertElement:
876 return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
877 case Instruction::ShuffleVector:
878 return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
879 case Instruction::GetElementPtr:
880 if (Constant *C = CastGEPIndices(Ops, NumOps, DestTy, TD))
882 if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, TD))
885 return ConstantExpr::getGetElementPtr(Ops[0], Ops+1, NumOps-1);
889 /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
890 /// instruction (icmp/fcmp) with the specified operands. If it fails, it
891 /// returns a constant expression of the specified operands.
893 Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
894 Constant *Ops0, Constant *Ops1,
895 const TargetData *TD) {
896 // fold: icmp (inttoptr x), null -> icmp x, 0
897 // fold: icmp (ptrtoint x), 0 -> icmp x, null
898 // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y
899 // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
901 // ConstantExpr::getCompare cannot do this, because it doesn't have TD
902 // around to know if bit truncation is happening.
903 if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops0)) {
904 if (TD && Ops1->isNullValue()) {
905 const Type *IntPtrTy = TD->getIntPtrType(CE0->getContext());
906 if (CE0->getOpcode() == Instruction::IntToPtr) {
907 // Convert the integer value to the right size to ensure we get the
908 // proper extension or truncation.
909 Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
911 Constant *Null = Constant::getNullValue(C->getType());
912 return ConstantFoldCompareInstOperands(Predicate, C, Null, TD);
915 // Only do this transformation if the int is intptrty in size, otherwise
916 // there is a truncation or extension that we aren't modeling.
917 if (CE0->getOpcode() == Instruction::PtrToInt &&
918 CE0->getType() == IntPtrTy) {
919 Constant *C = CE0->getOperand(0);
920 Constant *Null = Constant::getNullValue(C->getType());
921 return ConstantFoldCompareInstOperands(Predicate, C, Null, TD);
925 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops1)) {
926 if (TD && CE0->getOpcode() == CE1->getOpcode()) {
927 const Type *IntPtrTy = TD->getIntPtrType(CE0->getContext());
929 if (CE0->getOpcode() == Instruction::IntToPtr) {
930 // Convert the integer value to the right size to ensure we get the
931 // proper extension or truncation.
932 Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0),
934 Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
936 return ConstantFoldCompareInstOperands(Predicate, C0, C1, TD);
939 // Only do this transformation if the int is intptrty in size, otherwise
940 // there is a truncation or extension that we aren't modeling.
941 if ((CE0->getOpcode() == Instruction::PtrToInt &&
942 CE0->getType() == IntPtrTy &&
943 CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType()))
944 return ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0),
945 CE1->getOperand(0), TD);
949 // icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0)
950 // icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0)
951 if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) &&
952 CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) {
954 ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0), Ops1,TD);
956 ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(1), Ops1,TD);
958 Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
959 Constant *Ops[] = { LHS, RHS };
960 return ConstantFoldInstOperands(OpC, LHS->getType(), Ops, 2, TD);
964 return ConstantExpr::getCompare(Predicate, Ops0, Ops1);
968 /// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
969 /// getelementptr constantexpr, return the constant value being addressed by the
970 /// constant expression, or null if something is funny and we can't decide.
971 Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
973 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
974 return 0; // Do not allow stepping over the value!
976 // Loop over all of the operands, tracking down which value we are
978 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
979 for (++I; I != E; ++I)
980 if (const StructType *STy = dyn_cast<StructType>(*I)) {
981 ConstantInt *CU = cast<ConstantInt>(I.getOperand());
982 assert(CU->getZExtValue() < STy->getNumElements() &&
983 "Struct index out of range!");
984 unsigned El = (unsigned)CU->getZExtValue();
985 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
986 C = CS->getOperand(El);
987 } else if (isa<ConstantAggregateZero>(C)) {
988 C = Constant::getNullValue(STy->getElementType(El));
989 } else if (isa<UndefValue>(C)) {
990 C = UndefValue::get(STy->getElementType(El));
994 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
995 if (const ArrayType *ATy = dyn_cast<ArrayType>(*I)) {
996 if (CI->getZExtValue() >= ATy->getNumElements())
998 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
999 C = CA->getOperand(CI->getZExtValue());
1000 else if (isa<ConstantAggregateZero>(C))
1001 C = Constant::getNullValue(ATy->getElementType());
1002 else if (isa<UndefValue>(C))
1003 C = UndefValue::get(ATy->getElementType());
1006 } else if (const VectorType *VTy = dyn_cast<VectorType>(*I)) {
1007 if (CI->getZExtValue() >= VTy->getNumElements())
1009 if (ConstantVector *CP = dyn_cast<ConstantVector>(C))
1010 C = CP->getOperand(CI->getZExtValue());
1011 else if (isa<ConstantAggregateZero>(C))
1012 C = Constant::getNullValue(VTy->getElementType());
1013 else if (isa<UndefValue>(C))
1014 C = UndefValue::get(VTy->getElementType());
1027 //===----------------------------------------------------------------------===//
1028 // Constant Folding for Calls
1031 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
1032 /// the specified function.
1034 llvm::canConstantFoldCallTo(const Function *F) {
1035 switch (F->getIntrinsicID()) {
1036 case Intrinsic::sqrt:
1037 case Intrinsic::powi:
1038 case Intrinsic::bswap:
1039 case Intrinsic::ctpop:
1040 case Intrinsic::ctlz:
1041 case Intrinsic::cttz:
1042 case Intrinsic::uadd_with_overflow:
1043 case Intrinsic::usub_with_overflow:
1044 case Intrinsic::sadd_with_overflow:
1045 case Intrinsic::ssub_with_overflow:
1046 case Intrinsic::smul_with_overflow:
1047 case Intrinsic::convert_from_fp16:
1048 case Intrinsic::convert_to_fp16:
1055 if (!F->hasName()) return false;
1056 StringRef Name = F->getName();
1058 // In these cases, the check of the length is required. We don't want to
1059 // return true for a name like "cos\0blah" which strcmp would return equal to
1060 // "cos", but has length 8.
1062 default: return false;
1064 return Name == "acos" || Name == "asin" ||
1065 Name == "atan" || Name == "atan2";
1067 return Name == "cos" || Name == "ceil" || Name == "cosf" || Name == "cosh";
1069 return Name == "exp";
1071 return Name == "fabs" || Name == "fmod" || Name == "floor";
1073 return Name == "log" || Name == "log10";
1075 return Name == "pow";
1077 return Name == "sin" || Name == "sinh" || Name == "sqrt" ||
1078 Name == "sinf" || Name == "sqrtf";
1080 return Name == "tan" || Name == "tanh";
1084 static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
1086 sys::llvm_fenv_clearexcept();
1088 if (sys::llvm_fenv_testexcept()) {
1089 sys::llvm_fenv_clearexcept();
1093 if (Ty->isFloatTy())
1094 return ConstantFP::get(Ty->getContext(), APFloat((float)V));
1095 if (Ty->isDoubleTy())
1096 return ConstantFP::get(Ty->getContext(), APFloat(V));
1097 llvm_unreachable("Can only constant fold float/double");
1098 return 0; // dummy return to suppress warning
1101 static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
1102 double V, double W, const Type *Ty) {
1103 sys::llvm_fenv_clearexcept();
1105 if (sys::llvm_fenv_testexcept()) {
1106 sys::llvm_fenv_clearexcept();
1110 if (Ty->isFloatTy())
1111 return ConstantFP::get(Ty->getContext(), APFloat((float)V));
1112 if (Ty->isDoubleTy())
1113 return ConstantFP::get(Ty->getContext(), APFloat(V));
1114 llvm_unreachable("Can only constant fold float/double");
1115 return 0; // dummy return to suppress warning
1118 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
1119 /// with the specified arguments, returning null if unsuccessful.
1121 llvm::ConstantFoldCall(Function *F,
1122 Constant *const *Operands, unsigned NumOperands) {
1123 if (!F->hasName()) return 0;
1124 StringRef Name = F->getName();
1126 const Type *Ty = F->getReturnType();
1127 if (NumOperands == 1) {
1128 if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
1129 if (Name == "llvm.convert.to.fp16") {
1130 APFloat Val(Op->getValueAPF());
1133 Val.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &lost);
1135 return ConstantInt::get(F->getContext(), Val.bitcastToAPInt());
1138 if (!Ty->isFloatTy() && !Ty->isDoubleTy())
1141 /// We only fold functions with finite arguments. Folding NaN and inf is
1142 /// likely to be aborted with an exception anyway, and some host libms
1143 /// have known errors raising exceptions.
1144 if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity())
1147 /// Currently APFloat versions of these functions do not exist, so we use
1148 /// the host native double versions. Float versions are not called
1149 /// directly but for all these it is true (float)(f((double)arg)) ==
1150 /// f(arg). Long double not supported yet.
1151 double V = Ty->isFloatTy() ? (double)Op->getValueAPF().convertToFloat() :
1152 Op->getValueAPF().convertToDouble();
1156 return ConstantFoldFP(acos, V, Ty);
1157 else if (Name == "asin")
1158 return ConstantFoldFP(asin, V, Ty);
1159 else if (Name == "atan")
1160 return ConstantFoldFP(atan, V, Ty);
1164 return ConstantFoldFP(ceil, V, Ty);
1165 else if (Name == "cos")
1166 return ConstantFoldFP(cos, V, Ty);
1167 else if (Name == "cosh")
1168 return ConstantFoldFP(cosh, V, Ty);
1169 else if (Name == "cosf")
1170 return ConstantFoldFP(cos, V, Ty);
1174 return ConstantFoldFP(exp, V, Ty);
1178 return ConstantFoldFP(fabs, V, Ty);
1179 else if (Name == "floor")
1180 return ConstantFoldFP(floor, V, Ty);
1183 if (Name == "log" && V > 0)
1184 return ConstantFoldFP(log, V, Ty);
1185 else if (Name == "log10" && V > 0)
1186 return ConstantFoldFP(log10, V, Ty);
1187 else if (Name == "llvm.sqrt.f32" ||
1188 Name == "llvm.sqrt.f64") {
1190 return ConstantFoldFP(sqrt, V, Ty);
1192 return Constant::getNullValue(Ty);
1197 return ConstantFoldFP(sin, V, Ty);
1198 else if (Name == "sinh")
1199 return ConstantFoldFP(sinh, V, Ty);
1200 else if (Name == "sqrt" && V >= 0)
1201 return ConstantFoldFP(sqrt, V, Ty);
1202 else if (Name == "sqrtf" && V >= 0)
1203 return ConstantFoldFP(sqrt, V, Ty);
1204 else if (Name == "sinf")
1205 return ConstantFoldFP(sin, V, Ty);
1209 return ConstantFoldFP(tan, V, Ty);
1210 else if (Name == "tanh")
1211 return ConstantFoldFP(tanh, V, Ty);
1220 if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
1221 if (Name.startswith("llvm.bswap"))
1222 return ConstantInt::get(F->getContext(), Op->getValue().byteSwap());
1223 else if (Name.startswith("llvm.ctpop"))
1224 return ConstantInt::get(Ty, Op->getValue().countPopulation());
1225 else if (Name.startswith("llvm.cttz"))
1226 return ConstantInt::get(Ty, Op->getValue().countTrailingZeros());
1227 else if (Name.startswith("llvm.ctlz"))
1228 return ConstantInt::get(Ty, Op->getValue().countLeadingZeros());
1229 else if (Name == "llvm.convert.from.fp16") {
1230 APFloat Val(Op->getValue());
1233 APFloat::opStatus status =
1234 Val.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, &lost);
1236 // Conversion is always precise.
1238 assert(status == APFloat::opOK && !lost &&
1239 "Precision lost during fp16 constfolding");
1241 return ConstantFP::get(F->getContext(), Val);
1246 if (isa<UndefValue>(Operands[0])) {
1247 if (Name.startswith("llvm.bswap"))
1255 if (NumOperands == 2) {
1256 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
1257 if (!Ty->isFloatTy() && !Ty->isDoubleTy())
1259 double Op1V = Ty->isFloatTy() ?
1260 (double)Op1->getValueAPF().convertToFloat() :
1261 Op1->getValueAPF().convertToDouble();
1262 if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
1263 if (Op2->getType() != Op1->getType())
1266 double Op2V = Ty->isFloatTy() ?
1267 (double)Op2->getValueAPF().convertToFloat():
1268 Op2->getValueAPF().convertToDouble();
1271 return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
1273 return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty);
1274 if (Name == "atan2")
1275 return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
1276 } else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
1277 if (Name == "llvm.powi.f32")
1278 return ConstantFP::get(F->getContext(),
1279 APFloat((float)std::pow((float)Op1V,
1280 (int)Op2C->getZExtValue())));
1281 if (Name == "llvm.powi.f64")
1282 return ConstantFP::get(F->getContext(),
1283 APFloat((double)std::pow((double)Op1V,
1284 (int)Op2C->getZExtValue())));
1290 if (ConstantInt *Op1 = dyn_cast<ConstantInt>(Operands[0])) {
1291 if (ConstantInt *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
1292 switch (F->getIntrinsicID()) {
1294 case Intrinsic::sadd_with_overflow:
1295 case Intrinsic::uadd_with_overflow:
1296 case Intrinsic::ssub_with_overflow:
1297 case Intrinsic::usub_with_overflow:
1298 case Intrinsic::smul_with_overflow: {
1301 switch (F->getIntrinsicID()) {
1302 default: assert(0 && "Invalid case");
1303 case Intrinsic::sadd_with_overflow:
1304 Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow);
1306 case Intrinsic::uadd_with_overflow:
1307 Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow);
1309 case Intrinsic::ssub_with_overflow:
1310 Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow);
1312 case Intrinsic::usub_with_overflow:
1313 Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow);
1315 case Intrinsic::smul_with_overflow:
1316 Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow);
1320 ConstantInt::get(F->getContext(), Res),
1321 ConstantInt::get(Type::getInt1Ty(F->getContext()), Overflow)
1323 return ConstantStruct::get(F->getContext(), Ops, 2, false);