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/Operator.h"
27 #include "llvm/Analysis/ValueTracking.h"
28 #include "llvm/Target/TargetData.h"
29 #include "llvm/Target/TargetLibraryInfo.h"
30 #include "llvm/ADT/SmallVector.h"
31 #include "llvm/ADT/StringMap.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/GetElementPtrTypeIterator.h"
34 #include "llvm/Support/MathExtras.h"
35 #include "llvm/Support/FEnv.h"
40 //===----------------------------------------------------------------------===//
41 // Constant Folding internal helper functions
42 //===----------------------------------------------------------------------===//
44 /// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
45 /// TargetData. This always returns a non-null constant, but it may be a
46 /// ConstantExpr if unfoldable.
47 static Constant *FoldBitCast(Constant *C, Type *DestTy,
48 const TargetData &TD) {
49 // Catch the obvious splat cases.
50 if (C->isNullValue() && !DestTy->isX86_MMXTy())
51 return Constant::getNullValue(DestTy);
52 if (C->isAllOnesValue() && !DestTy->isX86_MMXTy())
53 return Constant::getAllOnesValue(DestTy);
55 // Handle a vector->integer cast.
56 if (IntegerType *IT = dyn_cast<IntegerType>(DestTy)) {
57 ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(C);
59 return ConstantExpr::getBitCast(C, DestTy);
61 unsigned NumSrcElts = CDV->getType()->getNumElements();
63 Type *SrcEltTy = CDV->getType()->getElementType();
65 // If the vector is a vector of floating point, convert it to vector of int
66 // to simplify things.
67 if (SrcEltTy->isFloatingPointTy()) {
68 unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
70 VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElts);
71 // Ask VMCore to do the conversion now that #elts line up.
72 C = ConstantExpr::getBitCast(C, SrcIVTy);
73 CDV = cast<ConstantDataVector>(C);
76 // Now that we know that the input value is a vector of integers, just shift
77 // and insert them into our result.
78 unsigned BitShift = TD.getTypeAllocSizeInBits(SrcEltTy);
79 APInt Result(IT->getBitWidth(), 0);
80 for (unsigned i = 0; i != NumSrcElts; ++i) {
82 if (TD.isLittleEndian())
83 Result |= CDV->getElementAsInteger(NumSrcElts-i-1);
85 Result |= CDV->getElementAsInteger(i);
88 return ConstantInt::get(IT, Result);
91 // The code below only handles casts to vectors currently.
92 VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
94 return ConstantExpr::getBitCast(C, DestTy);
96 // If this is a scalar -> vector cast, convert the input into a <1 x scalar>
97 // vector so the code below can handle it uniformly.
98 if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) {
99 Constant *Ops = C; // don't take the address of C!
100 return FoldBitCast(ConstantVector::get(Ops), DestTy, TD);
103 // If this is a bitcast from constant vector -> vector, fold it.
104 if (!isa<ConstantDataVector>(C) && !isa<ConstantVector>(C))
105 return ConstantExpr::getBitCast(C, DestTy);
107 // If the element types match, VMCore can fold it.
108 unsigned NumDstElt = DestVTy->getNumElements();
109 unsigned NumSrcElt = C->getType()->getVectorNumElements();
110 if (NumDstElt == NumSrcElt)
111 return ConstantExpr::getBitCast(C, DestTy);
113 Type *SrcEltTy = C->getType()->getVectorElementType();
114 Type *DstEltTy = DestVTy->getElementType();
116 // Otherwise, we're changing the number of elements in a vector, which
117 // requires endianness information to do the right thing. For example,
118 // bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
119 // folds to (little endian):
120 // <4 x i32> <i32 0, i32 0, i32 1, i32 0>
121 // and to (big endian):
122 // <4 x i32> <i32 0, i32 0, i32 0, i32 1>
124 // First thing is first. We only want to think about integer here, so if
125 // we have something in FP form, recast it as integer.
126 if (DstEltTy->isFloatingPointTy()) {
127 // Fold to an vector of integers with same size as our FP type.
128 unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
130 VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt);
131 // Recursively handle this integer conversion, if possible.
132 C = FoldBitCast(C, DestIVTy, TD);
134 // Finally, VMCore can handle this now that #elts line up.
135 return ConstantExpr::getBitCast(C, DestTy);
138 // Okay, we know the destination is integer, if the input is FP, convert
139 // it to integer first.
140 if (SrcEltTy->isFloatingPointTy()) {
141 unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
143 VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
144 // Ask VMCore to do the conversion now that #elts line up.
145 C = ConstantExpr::getBitCast(C, SrcIVTy);
146 // If VMCore wasn't able to fold it, bail out.
147 if (!isa<ConstantVector>(C) && // FIXME: Remove ConstantVector.
148 !isa<ConstantDataVector>(C))
152 // Now we know that the input and output vectors are both integer vectors
153 // of the same size, and that their #elements is not the same. Do the
154 // conversion here, which depends on whether the input or output has
156 bool isLittleEndian = TD.isLittleEndian();
158 SmallVector<Constant*, 32> Result;
159 if (NumDstElt < NumSrcElt) {
160 // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
161 Constant *Zero = Constant::getNullValue(DstEltTy);
162 unsigned Ratio = NumSrcElt/NumDstElt;
163 unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
165 for (unsigned i = 0; i != NumDstElt; ++i) {
166 // Build each element of the result.
167 Constant *Elt = Zero;
168 unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
169 for (unsigned j = 0; j != Ratio; ++j) {
170 Constant *Src =dyn_cast<ConstantInt>(C->getAggregateElement(SrcElt++));
171 if (!Src) // Reject constantexpr elements.
172 return ConstantExpr::getBitCast(C, DestTy);
174 // Zero extend the element to the right size.
175 Src = ConstantExpr::getZExt(Src, Elt->getType());
177 // Shift it to the right place, depending on endianness.
178 Src = ConstantExpr::getShl(Src,
179 ConstantInt::get(Src->getType(), ShiftAmt));
180 ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
183 Elt = ConstantExpr::getOr(Elt, Src);
185 Result.push_back(Elt);
187 return ConstantVector::get(Result);
190 // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
191 unsigned Ratio = NumDstElt/NumSrcElt;
192 unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
194 // Loop over each source value, expanding into multiple results.
195 for (unsigned i = 0; i != NumSrcElt; ++i) {
196 Constant *Src = dyn_cast<ConstantInt>(C->getAggregateElement(i));
197 if (!Src) // Reject constantexpr elements.
198 return ConstantExpr::getBitCast(C, DestTy);
200 unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
201 for (unsigned j = 0; j != Ratio; ++j) {
202 // Shift the piece of the value into the right place, depending on
204 Constant *Elt = ConstantExpr::getLShr(Src,
205 ConstantInt::get(Src->getType(), ShiftAmt));
206 ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
208 // Truncate and remember this piece.
209 Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
213 return ConstantVector::get(Result);
217 /// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
218 /// from a global, return the global and the constant. Because of
219 /// constantexprs, this function is recursive.
220 static bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
221 int64_t &Offset, const TargetData &TD) {
222 // Trivial case, constant is the global.
223 if ((GV = dyn_cast<GlobalValue>(C))) {
228 // Otherwise, if this isn't a constant expr, bail out.
229 ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
230 if (!CE) return false;
232 // Look through ptr->int and ptr->ptr casts.
233 if (CE->getOpcode() == Instruction::PtrToInt ||
234 CE->getOpcode() == Instruction::BitCast)
235 return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD);
237 // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
238 if (CE->getOpcode() == Instruction::GetElementPtr) {
239 // Cannot compute this if the element type of the pointer is missing size
241 if (!cast<PointerType>(CE->getOperand(0)->getType())
242 ->getElementType()->isSized())
245 // If the base isn't a global+constant, we aren't either.
246 if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD))
249 // Otherwise, add any offset that our operands provide.
250 gep_type_iterator GTI = gep_type_begin(CE);
251 for (User::const_op_iterator i = CE->op_begin() + 1, e = CE->op_end();
252 i != e; ++i, ++GTI) {
253 ConstantInt *CI = dyn_cast<ConstantInt>(*i);
254 if (!CI) return false; // Index isn't a simple constant?
255 if (CI->isZero()) continue; // Not adding anything.
257 if (StructType *ST = dyn_cast<StructType>(*GTI)) {
259 Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue());
261 SequentialType *SQT = cast<SequentialType>(*GTI);
262 Offset += TD.getTypeAllocSize(SQT->getElementType())*CI->getSExtValue();
271 /// ReadDataFromGlobal - Recursive helper to read bits out of global. C is the
272 /// constant being copied out of. ByteOffset is an offset into C. CurPtr is the
273 /// pointer to copy results into and BytesLeft is the number of bytes left in
274 /// the CurPtr buffer. TD is the target data.
275 static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
276 unsigned char *CurPtr, unsigned BytesLeft,
277 const TargetData &TD) {
278 assert(ByteOffset <= TD.getTypeAllocSize(C->getType()) &&
279 "Out of range access");
281 // If this element is zero or undefined, we can just return since *CurPtr is
283 if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C))
286 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
287 if (CI->getBitWidth() > 64 ||
288 (CI->getBitWidth() & 7) != 0)
291 uint64_t Val = CI->getZExtValue();
292 unsigned IntBytes = unsigned(CI->getBitWidth()/8);
294 for (unsigned i = 0; i != BytesLeft && ByteOffset != IntBytes; ++i) {
295 CurPtr[i] = (unsigned char)(Val >> (ByteOffset * 8));
301 if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
302 if (CFP->getType()->isDoubleTy()) {
303 C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), TD);
304 return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
306 if (CFP->getType()->isFloatTy()){
307 C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD);
308 return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
313 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
314 const StructLayout *SL = TD.getStructLayout(CS->getType());
315 unsigned Index = SL->getElementContainingOffset(ByteOffset);
316 uint64_t CurEltOffset = SL->getElementOffset(Index);
317 ByteOffset -= CurEltOffset;
320 // If the element access is to the element itself and not to tail padding,
321 // read the bytes from the element.
322 uint64_t EltSize = TD.getTypeAllocSize(CS->getOperand(Index)->getType());
324 if (ByteOffset < EltSize &&
325 !ReadDataFromGlobal(CS->getOperand(Index), ByteOffset, CurPtr,
331 // Check to see if we read from the last struct element, if so we're done.
332 if (Index == CS->getType()->getNumElements())
335 // If we read all of the bytes we needed from this element we're done.
336 uint64_t NextEltOffset = SL->getElementOffset(Index);
338 if (BytesLeft <= NextEltOffset-CurEltOffset-ByteOffset)
341 // Move to the next element of the struct.
342 CurPtr += NextEltOffset-CurEltOffset-ByteOffset;
343 BytesLeft -= NextEltOffset-CurEltOffset-ByteOffset;
345 CurEltOffset = NextEltOffset;
350 if (isa<ConstantArray>(C) || isa<ConstantVector>(C) ||
351 isa<ConstantDataSequential>(C)) {
352 Type *EltTy = cast<SequentialType>(C->getType())->getElementType();
353 uint64_t EltSize = TD.getTypeAllocSize(EltTy);
354 uint64_t Index = ByteOffset / EltSize;
355 uint64_t Offset = ByteOffset - Index * EltSize;
357 if (ArrayType *AT = dyn_cast<ArrayType>(C->getType()))
358 NumElts = AT->getNumElements();
360 NumElts = cast<VectorType>(C->getType())->getNumElements();
362 for (; Index != NumElts; ++Index) {
363 if (!ReadDataFromGlobal(C->getAggregateElement(Index), Offset, CurPtr,
367 uint64_t BytesWritten = EltSize - Offset;
368 assert(BytesWritten <= EltSize && "Not indexing into this element?");
369 if (BytesWritten >= BytesLeft)
373 BytesLeft -= BytesWritten;
374 CurPtr += BytesWritten;
379 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
380 if (CE->getOpcode() == Instruction::IntToPtr &&
381 CE->getOperand(0)->getType() == TD.getIntPtrType(CE->getContext()))
382 return ReadDataFromGlobal(CE->getOperand(0), ByteOffset, CurPtr,
386 // Otherwise, unknown initializer type.
390 static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
391 const TargetData &TD) {
392 Type *LoadTy = cast<PointerType>(C->getType())->getElementType();
393 IntegerType *IntType = dyn_cast<IntegerType>(LoadTy);
395 // If this isn't an integer load we can't fold it directly.
397 // If this is a float/double load, we can try folding it as an int32/64 load
398 // and then bitcast the result. This can be useful for union cases. Note
399 // that address spaces don't matter here since we're not going to result in
400 // an actual new load.
402 if (LoadTy->isFloatTy())
403 MapTy = Type::getInt32PtrTy(C->getContext());
404 else if (LoadTy->isDoubleTy())
405 MapTy = Type::getInt64PtrTy(C->getContext());
406 else if (LoadTy->isVectorTy()) {
407 MapTy = IntegerType::get(C->getContext(),
408 TD.getTypeAllocSizeInBits(LoadTy));
409 MapTy = PointerType::getUnqual(MapTy);
413 C = FoldBitCast(C, MapTy, TD);
414 if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD))
415 return FoldBitCast(Res, LoadTy, TD);
419 unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
420 if (BytesLoaded > 32 || BytesLoaded == 0) return 0;
424 if (!IsConstantOffsetFromGlobal(C, GVal, Offset, TD))
427 GlobalVariable *GV = dyn_cast<GlobalVariable>(GVal);
428 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
429 !GV->getInitializer()->getType()->isSized())
432 // If we're loading off the beginning of the global, some bytes may be valid,
433 // but we don't try to handle this.
434 if (Offset < 0) return 0;
436 // If we're not accessing anything in this constant, the result is undefined.
437 if (uint64_t(Offset) >= TD.getTypeAllocSize(GV->getInitializer()->getType()))
438 return UndefValue::get(IntType);
440 unsigned char RawBytes[32] = {0};
441 if (!ReadDataFromGlobal(GV->getInitializer(), Offset, RawBytes,
445 APInt ResultVal = APInt(IntType->getBitWidth(), RawBytes[BytesLoaded-1]);
446 for (unsigned i = 1; i != BytesLoaded; ++i) {
448 ResultVal |= RawBytes[BytesLoaded-1-i];
451 return ConstantInt::get(IntType->getContext(), ResultVal);
454 /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
455 /// produce if it is constant and determinable. If this is not determinable,
457 Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
458 const TargetData *TD) {
459 // First, try the easy cases:
460 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
461 if (GV->isConstant() && GV->hasDefinitiveInitializer())
462 return GV->getInitializer();
464 // If the loaded value isn't a constant expr, we can't handle it.
465 ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
468 if (CE->getOpcode() == Instruction::GetElementPtr) {
469 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
470 if (GV->isConstant() && GV->hasDefinitiveInitializer())
472 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
476 // Instead of loading constant c string, use corresponding integer value
477 // directly if string length is small enough.
479 if (TD && getConstantStringInfo(CE, Str) && !Str.empty()) {
480 unsigned StrLen = Str.size();
481 Type *Ty = cast<PointerType>(CE->getType())->getElementType();
482 unsigned NumBits = Ty->getPrimitiveSizeInBits();
483 // Replace load with immediate integer if the result is an integer or fp
485 if ((NumBits >> 3) == StrLen + 1 && (NumBits & 7) == 0 &&
486 (isa<IntegerType>(Ty) || Ty->isFloatingPointTy())) {
487 APInt StrVal(NumBits, 0);
488 APInt SingleChar(NumBits, 0);
489 if (TD->isLittleEndian()) {
490 for (signed i = StrLen-1; i >= 0; i--) {
491 SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
492 StrVal = (StrVal << 8) | SingleChar;
495 for (unsigned i = 0; i < StrLen; i++) {
496 SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
497 StrVal = (StrVal << 8) | SingleChar;
499 // Append NULL at the end.
501 StrVal = (StrVal << 8) | SingleChar;
504 Constant *Res = ConstantInt::get(CE->getContext(), StrVal);
505 if (Ty->isFloatingPointTy())
506 Res = ConstantExpr::getBitCast(Res, Ty);
511 // If this load comes from anywhere in a constant global, and if the global
512 // is all undef or zero, we know what it loads.
513 if (GlobalVariable *GV =
514 dyn_cast<GlobalVariable>(GetUnderlyingObject(CE, TD))) {
515 if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
516 Type *ResTy = cast<PointerType>(C->getType())->getElementType();
517 if (GV->getInitializer()->isNullValue())
518 return Constant::getNullValue(ResTy);
519 if (isa<UndefValue>(GV->getInitializer()))
520 return UndefValue::get(ResTy);
524 // Try hard to fold loads from bitcasted strange and non-type-safe things. We
525 // currently don't do any of this for big endian systems. It can be
526 // generalized in the future if someone is interested.
527 if (TD && TD->isLittleEndian())
528 return FoldReinterpretLoadFromConstPtr(CE, *TD);
532 static Constant *ConstantFoldLoadInst(const LoadInst *LI, const TargetData *TD){
533 if (LI->isVolatile()) return 0;
535 if (Constant *C = dyn_cast<Constant>(LI->getOperand(0)))
536 return ConstantFoldLoadFromConstPtr(C, TD);
541 /// SymbolicallyEvaluateBinop - One of Op0/Op1 is a constant expression.
542 /// Attempt to symbolically evaluate the result of a binary operator merging
543 /// these together. If target data info is available, it is provided as TD,
544 /// otherwise TD is null.
545 static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0,
546 Constant *Op1, const TargetData *TD){
549 // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
550 // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute
554 // If the constant expr is something like &A[123] - &A[4].f, fold this into a
555 // constant. This happens frequently when iterating over a global array.
556 if (Opc == Instruction::Sub && TD) {
557 GlobalValue *GV1, *GV2;
558 int64_t Offs1, Offs2;
560 if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, *TD))
561 if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, *TD) &&
563 // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
564 return ConstantInt::get(Op0->getType(), Offs1-Offs2);
571 /// CastGEPIndices - If array indices are not pointer-sized integers,
572 /// explicitly cast them so that they aren't implicitly casted by the
574 static Constant *CastGEPIndices(ArrayRef<Constant *> Ops,
575 Type *ResultTy, const TargetData *TD,
576 const TargetLibraryInfo *TLI) {
578 Type *IntPtrTy = TD->getIntPtrType(ResultTy->getContext());
581 SmallVector<Constant*, 32> NewIdxs;
582 for (unsigned i = 1, e = Ops.size(); i != e; ++i) {
584 !isa<StructType>(GetElementPtrInst::getIndexedType(Ops[0]->getType(),
585 Ops.slice(1, i-1)))) &&
586 Ops[i]->getType() != IntPtrTy) {
588 NewIdxs.push_back(ConstantExpr::getCast(CastInst::getCastOpcode(Ops[i],
594 NewIdxs.push_back(Ops[i]);
599 ConstantExpr::getGetElementPtr(Ops[0], NewIdxs);
600 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
601 if (Constant *Folded = ConstantFoldConstantExpression(CE, TD, TLI))
606 /// Strip the pointer casts, but preserve the address space information.
607 static Constant* StripPtrCastKeepAS(Constant* Ptr) {
608 assert(Ptr->getType()->isPointerTy() && "Not a pointer type");
609 PointerType *OldPtrTy = cast<PointerType>(Ptr->getType());
610 Ptr = cast<Constant>(Ptr->stripPointerCasts());
611 PointerType *NewPtrTy = cast<PointerType>(Ptr->getType());
613 // Preserve the address space number of the pointer.
614 if (NewPtrTy->getAddressSpace() != OldPtrTy->getAddressSpace()) {
615 NewPtrTy = NewPtrTy->getElementType()->getPointerTo(
616 OldPtrTy->getAddressSpace());
617 Ptr = ConstantExpr::getBitCast(Ptr, NewPtrTy);
622 /// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
623 /// constant expression, do so.
624 static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops,
625 Type *ResultTy, const TargetData *TD,
626 const TargetLibraryInfo *TLI) {
627 Constant *Ptr = Ops[0];
628 if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()->isSized() ||
629 !Ptr->getType()->isPointerTy())
632 Type *IntPtrTy = TD->getIntPtrType(Ptr->getContext());
634 // If this is a constant expr gep that is effectively computing an
635 // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12'
636 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
637 if (!isa<ConstantInt>(Ops[i])) {
639 // If this is "gep i8* Ptr, (sub 0, V)", fold this as:
640 // "inttoptr (sub (ptrtoint Ptr), V)"
641 if (Ops.size() == 2 &&
642 cast<PointerType>(ResultTy)->getElementType()->isIntegerTy(8)) {
643 ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[1]);
644 assert((CE == 0 || CE->getType() == IntPtrTy) &&
645 "CastGEPIndices didn't canonicalize index types!");
646 if (CE && CE->getOpcode() == Instruction::Sub &&
647 CE->getOperand(0)->isNullValue()) {
648 Constant *Res = ConstantExpr::getPtrToInt(Ptr, CE->getType());
649 Res = ConstantExpr::getSub(Res, CE->getOperand(1));
650 Res = ConstantExpr::getIntToPtr(Res, ResultTy);
651 if (ConstantExpr *ResCE = dyn_cast<ConstantExpr>(Res))
652 Res = ConstantFoldConstantExpression(ResCE, TD, TLI);
659 unsigned BitWidth = TD->getTypeSizeInBits(IntPtrTy);
661 APInt(BitWidth, TD->getIndexedOffset(Ptr->getType(),
662 makeArrayRef((Value **)Ops.data() + 1,
664 Ptr = StripPtrCastKeepAS(Ptr);
666 // If this is a GEP of a GEP, fold it all into a single GEP.
667 while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
668 SmallVector<Value *, 4> NestedOps(GEP->op_begin()+1, GEP->op_end());
670 // Do not try the incorporate the sub-GEP if some index is not a number.
671 bool AllConstantInt = true;
672 for (unsigned i = 0, e = NestedOps.size(); i != e; ++i)
673 if (!isa<ConstantInt>(NestedOps[i])) {
674 AllConstantInt = false;
680 Ptr = cast<Constant>(GEP->getOperand(0));
681 Offset += APInt(BitWidth,
682 TD->getIndexedOffset(Ptr->getType(), NestedOps));
683 Ptr = StripPtrCastKeepAS(Ptr);
686 // If the base value for this address is a literal integer value, fold the
687 // getelementptr to the resulting integer value casted to the pointer type.
688 APInt BasePtr(BitWidth, 0);
689 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
690 if (CE->getOpcode() == Instruction::IntToPtr)
691 if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
692 BasePtr = Base->getValue().zextOrTrunc(BitWidth);
693 if (Ptr->isNullValue() || BasePtr != 0) {
694 Constant *C = ConstantInt::get(Ptr->getContext(), Offset+BasePtr);
695 return ConstantExpr::getIntToPtr(C, ResultTy);
698 // Otherwise form a regular getelementptr. Recompute the indices so that
699 // we eliminate over-indexing of the notional static type array bounds.
700 // This makes it easy to determine if the getelementptr is "inbounds".
701 // Also, this helps GlobalOpt do SROA on GlobalVariables.
702 Type *Ty = Ptr->getType();
703 assert(Ty->isPointerTy() && "Forming regular GEP of non-pointer type");
704 SmallVector<Constant*, 32> NewIdxs;
706 if (SequentialType *ATy = dyn_cast<SequentialType>(Ty)) {
707 if (ATy->isPointerTy()) {
708 // The only pointer indexing we'll do is on the first index of the GEP.
709 if (!NewIdxs.empty())
712 // Only handle pointers to sized types, not pointers to functions.
713 if (!ATy->getElementType()->isSized())
717 // Determine which element of the array the offset points into.
718 APInt ElemSize(BitWidth, TD->getTypeAllocSize(ATy->getElementType()));
719 IntegerType *IntPtrTy = TD->getIntPtrType(Ty->getContext());
721 // The element size is 0. This may be [0 x Ty]*, so just use a zero
722 // index for this level and proceed to the next level to see if it can
723 // accommodate the offset.
724 NewIdxs.push_back(ConstantInt::get(IntPtrTy, 0));
726 // The element size is non-zero divide the offset by the element
727 // size (rounding down), to compute the index at this level.
728 APInt NewIdx = Offset.udiv(ElemSize);
729 Offset -= NewIdx * ElemSize;
730 NewIdxs.push_back(ConstantInt::get(IntPtrTy, NewIdx));
732 Ty = ATy->getElementType();
733 } else if (StructType *STy = dyn_cast<StructType>(Ty)) {
734 // If we end up with an offset that isn't valid for this struct type, we
735 // can't re-form this GEP in a regular form, so bail out. The pointer
736 // operand likely went through casts that are necessary to make the GEP
738 const StructLayout &SL = *TD->getStructLayout(STy);
739 if (Offset.uge(SL.getSizeInBytes()))
742 // Determine which field of the struct the offset points into. The
743 // getZExtValue is fine as we've already ensured that the offset is
744 // within the range representable by the StructLayout API.
745 unsigned ElIdx = SL.getElementContainingOffset(Offset.getZExtValue());
746 NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
748 Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx));
749 Ty = STy->getTypeAtIndex(ElIdx);
751 // We've reached some non-indexable type.
754 } while (Ty != cast<PointerType>(ResultTy)->getElementType());
756 // If we haven't used up the entire offset by descending the static
757 // type, then the offset is pointing into the middle of an indivisible
758 // member, so we can't simplify it.
764 ConstantExpr::getGetElementPtr(Ptr, NewIdxs);
765 assert(cast<PointerType>(C->getType())->getElementType() == Ty &&
766 "Computed GetElementPtr has unexpected type!");
768 // If we ended up indexing a member with a type that doesn't match
769 // the type of what the original indices indexed, add a cast.
770 if (Ty != cast<PointerType>(ResultTy)->getElementType())
771 C = FoldBitCast(C, ResultTy, *TD);
778 //===----------------------------------------------------------------------===//
779 // Constant Folding public APIs
780 //===----------------------------------------------------------------------===//
782 /// ConstantFoldInstruction - Try to constant fold the specified instruction.
783 /// If successful, the constant result is returned, if not, null is returned.
784 /// Note that this fails if not all of the operands are constant. Otherwise,
785 /// this function can only fail when attempting to fold instructions like loads
786 /// and stores, which have no constant expression form.
787 Constant *llvm::ConstantFoldInstruction(Instruction *I,
788 const TargetData *TD,
789 const TargetLibraryInfo *TLI) {
790 // Handle PHI nodes quickly here...
791 if (PHINode *PN = dyn_cast<PHINode>(I)) {
792 Constant *CommonValue = 0;
794 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
795 Value *Incoming = PN->getIncomingValue(i);
796 // If the incoming value is undef then skip it. Note that while we could
797 // skip the value if it is equal to the phi node itself we choose not to
798 // because that would break the rule that constant folding only applies if
799 // all operands are constants.
800 if (isa<UndefValue>(Incoming))
802 // If the incoming value is not a constant, then give up.
803 Constant *C = dyn_cast<Constant>(Incoming);
806 // Fold the PHI's operands.
807 if (ConstantExpr *NewC = dyn_cast<ConstantExpr>(C))
808 C = ConstantFoldConstantExpression(NewC, TD, TLI);
809 // If the incoming value is a different constant to
810 // the one we saw previously, then give up.
811 if (CommonValue && C != CommonValue)
817 // If we reach here, all incoming values are the same constant or undef.
818 return CommonValue ? CommonValue : UndefValue::get(PN->getType());
821 // Scan the operand list, checking to see if they are all constants, if so,
822 // hand off to ConstantFoldInstOperands.
823 SmallVector<Constant*, 8> Ops;
824 for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) {
825 Constant *Op = dyn_cast<Constant>(*i);
827 return 0; // All operands not constant!
829 // Fold the Instruction's operands.
830 if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(Op))
831 Op = ConstantFoldConstantExpression(NewCE, TD, TLI);
836 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
837 return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
840 if (const LoadInst *LI = dyn_cast<LoadInst>(I))
841 return ConstantFoldLoadInst(LI, TD);
843 if (InsertValueInst *IVI = dyn_cast<InsertValueInst>(I))
844 return ConstantExpr::getInsertValue(
845 cast<Constant>(IVI->getAggregateOperand()),
846 cast<Constant>(IVI->getInsertedValueOperand()),
849 if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I))
850 return ConstantExpr::getExtractValue(
851 cast<Constant>(EVI->getAggregateOperand()),
854 return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, TD, TLI);
857 /// ConstantFoldConstantExpression - Attempt to fold the constant expression
858 /// using the specified TargetData. If successful, the constant result is
859 /// result is returned, if not, null is returned.
860 Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
861 const TargetData *TD,
862 const TargetLibraryInfo *TLI) {
863 SmallVector<Constant*, 8> Ops;
864 for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end();
866 Constant *NewC = cast<Constant>(*i);
867 // Recursively fold the ConstantExpr's operands.
868 if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC))
869 NewC = ConstantFoldConstantExpression(NewCE, TD, TLI);
874 return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
876 return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(), Ops, TD, TLI);
879 /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
880 /// specified opcode and operands. If successful, the constant result is
881 /// returned, if not, null is returned. Note that this function can fail when
882 /// attempting to fold instructions like loads and stores, which have no
883 /// constant expression form.
885 /// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
886 /// information, due to only being passed an opcode and operands. Constant
887 /// folding using this function strips this information.
889 Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, Type *DestTy,
890 ArrayRef<Constant *> Ops,
891 const TargetData *TD,
892 const TargetLibraryInfo *TLI) {
893 // Handle easy binops first.
894 if (Instruction::isBinaryOp(Opcode)) {
895 if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1]))
896 if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD))
899 return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
904 case Instruction::ICmp:
905 case Instruction::FCmp: llvm_unreachable("Invalid for compares");
906 case Instruction::Call:
907 if (Function *F = dyn_cast<Function>(Ops.back()))
908 if (canConstantFoldCallTo(F))
909 return ConstantFoldCall(F, Ops.slice(0, Ops.size() - 1), TLI);
911 case Instruction::PtrToInt:
912 // If the input is a inttoptr, eliminate the pair. This requires knowing
913 // the width of a pointer, so it can't be done in ConstantExpr::getCast.
914 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
915 if (TD && CE->getOpcode() == Instruction::IntToPtr) {
916 Constant *Input = CE->getOperand(0);
917 unsigned InWidth = Input->getType()->getScalarSizeInBits();
918 if (TD->getPointerSizeInBits() < InWidth) {
920 ConstantInt::get(CE->getContext(), APInt::getLowBitsSet(InWidth,
921 TD->getPointerSizeInBits()));
922 Input = ConstantExpr::getAnd(Input, Mask);
924 // Do a zext or trunc to get to the dest size.
925 return ConstantExpr::getIntegerCast(Input, DestTy, false);
928 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
929 case Instruction::IntToPtr:
930 // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
931 // the int size is >= the ptr size. This requires knowing the width of a
932 // pointer, so it can't be done in ConstantExpr::getCast.
933 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0]))
935 TD->getPointerSizeInBits() <= CE->getType()->getScalarSizeInBits() &&
936 CE->getOpcode() == Instruction::PtrToInt)
937 return FoldBitCast(CE->getOperand(0), DestTy, *TD);
939 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
940 case Instruction::Trunc:
941 case Instruction::ZExt:
942 case Instruction::SExt:
943 case Instruction::FPTrunc:
944 case Instruction::FPExt:
945 case Instruction::UIToFP:
946 case Instruction::SIToFP:
947 case Instruction::FPToUI:
948 case Instruction::FPToSI:
949 return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
950 case Instruction::BitCast:
952 return FoldBitCast(Ops[0], DestTy, *TD);
953 return ConstantExpr::getBitCast(Ops[0], DestTy);
954 case Instruction::Select:
955 return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
956 case Instruction::ExtractElement:
957 return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
958 case Instruction::InsertElement:
959 return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
960 case Instruction::ShuffleVector:
961 return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
962 case Instruction::GetElementPtr:
963 if (Constant *C = CastGEPIndices(Ops, DestTy, TD, TLI))
965 if (Constant *C = SymbolicallyEvaluateGEP(Ops, DestTy, TD, TLI))
968 return ConstantExpr::getGetElementPtr(Ops[0], Ops.slice(1));
972 /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
973 /// instruction (icmp/fcmp) with the specified operands. If it fails, it
974 /// returns a constant expression of the specified operands.
976 Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
977 Constant *Ops0, Constant *Ops1,
978 const TargetData *TD,
979 const TargetLibraryInfo *TLI) {
980 // fold: icmp (inttoptr x), null -> icmp x, 0
981 // fold: icmp (ptrtoint x), 0 -> icmp x, null
982 // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y
983 // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
985 // ConstantExpr::getCompare cannot do this, because it doesn't have TD
986 // around to know if bit truncation is happening.
987 if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops0)) {
988 if (TD && Ops1->isNullValue()) {
989 Type *IntPtrTy = TD->getIntPtrType(CE0->getContext());
990 if (CE0->getOpcode() == Instruction::IntToPtr) {
991 // Convert the integer value to the right size to ensure we get the
992 // proper extension or truncation.
993 Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
995 Constant *Null = Constant::getNullValue(C->getType());
996 return ConstantFoldCompareInstOperands(Predicate, C, Null, TD, TLI);
999 // Only do this transformation if the int is intptrty in size, otherwise
1000 // there is a truncation or extension that we aren't modeling.
1001 if (CE0->getOpcode() == Instruction::PtrToInt &&
1002 CE0->getType() == IntPtrTy) {
1003 Constant *C = CE0->getOperand(0);
1004 Constant *Null = Constant::getNullValue(C->getType());
1005 return ConstantFoldCompareInstOperands(Predicate, C, Null, TD, TLI);
1009 if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops1)) {
1010 if (TD && CE0->getOpcode() == CE1->getOpcode()) {
1011 Type *IntPtrTy = TD->getIntPtrType(CE0->getContext());
1013 if (CE0->getOpcode() == Instruction::IntToPtr) {
1014 // Convert the integer value to the right size to ensure we get the
1015 // proper extension or truncation.
1016 Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0),
1018 Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
1020 return ConstantFoldCompareInstOperands(Predicate, C0, C1, TD, TLI);
1023 // Only do this transformation if the int is intptrty in size, otherwise
1024 // there is a truncation or extension that we aren't modeling.
1025 if ((CE0->getOpcode() == Instruction::PtrToInt &&
1026 CE0->getType() == IntPtrTy &&
1027 CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType()))
1028 return ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0),
1029 CE1->getOperand(0), TD, TLI);
1033 // icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0)
1034 // icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0)
1035 if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) &&
1036 CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) {
1038 ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0), Ops1,
1041 ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(1), Ops1,
1044 Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
1045 Constant *Ops[] = { LHS, RHS };
1046 return ConstantFoldInstOperands(OpC, LHS->getType(), Ops, TD, TLI);
1050 return ConstantExpr::getCompare(Predicate, Ops0, Ops1);
1054 /// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
1055 /// getelementptr constantexpr, return the constant value being addressed by the
1056 /// constant expression, or null if something is funny and we can't decide.
1057 Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
1059 if (!CE->getOperand(1)->isNullValue())
1060 return 0; // Do not allow stepping over the value!
1062 // Loop over all of the operands, tracking down which value we are
1064 for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i) {
1065 C = C->getAggregateElement(CE->getOperand(i));
1066 if (C == 0) return 0;
1071 /// ConstantFoldLoadThroughGEPIndices - Given a constant and getelementptr
1072 /// indices (with an *implied* zero pointer index that is not in the list),
1073 /// return the constant value being addressed by a virtual load, or null if
1074 /// something is funny and we can't decide.
1075 Constant *llvm::ConstantFoldLoadThroughGEPIndices(Constant *C,
1076 ArrayRef<Constant*> Indices) {
1077 // Loop over all of the operands, tracking down which value we are
1079 for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
1080 C = C->getAggregateElement(Indices[i]);
1081 if (C == 0) return 0;
1087 //===----------------------------------------------------------------------===//
1088 // Constant Folding for Calls
1091 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
1092 /// the specified function.
1094 llvm::canConstantFoldCallTo(const Function *F) {
1095 switch (F->getIntrinsicID()) {
1096 case Intrinsic::sqrt:
1097 case Intrinsic::pow:
1098 case Intrinsic::powi:
1099 case Intrinsic::bswap:
1100 case Intrinsic::ctpop:
1101 case Intrinsic::ctlz:
1102 case Intrinsic::cttz:
1103 case Intrinsic::sadd_with_overflow:
1104 case Intrinsic::uadd_with_overflow:
1105 case Intrinsic::ssub_with_overflow:
1106 case Intrinsic::usub_with_overflow:
1107 case Intrinsic::smul_with_overflow:
1108 case Intrinsic::umul_with_overflow:
1109 case Intrinsic::convert_from_fp16:
1110 case Intrinsic::convert_to_fp16:
1111 case Intrinsic::x86_sse_cvtss2si:
1112 case Intrinsic::x86_sse_cvtss2si64:
1113 case Intrinsic::x86_sse_cvttss2si:
1114 case Intrinsic::x86_sse_cvttss2si64:
1115 case Intrinsic::x86_sse2_cvtsd2si:
1116 case Intrinsic::x86_sse2_cvtsd2si64:
1117 case Intrinsic::x86_sse2_cvttsd2si:
1118 case Intrinsic::x86_sse2_cvttsd2si64:
1125 if (!F->hasName()) return false;
1126 StringRef Name = F->getName();
1128 // In these cases, the check of the length is required. We don't want to
1129 // return true for a name like "cos\0blah" which strcmp would return equal to
1130 // "cos", but has length 8.
1132 default: return false;
1134 return Name == "acos" || Name == "asin" ||
1135 Name == "atan" || Name == "atan2";
1137 return Name == "cos" || Name == "ceil" || Name == "cosf" || Name == "cosh";
1139 return Name == "exp" || Name == "exp2";
1141 return Name == "fabs" || Name == "fmod" || Name == "floor";
1143 return Name == "log" || Name == "log10";
1145 return Name == "pow";
1147 return Name == "sin" || Name == "sinh" || Name == "sqrt" ||
1148 Name == "sinf" || Name == "sqrtf";
1150 return Name == "tan" || Name == "tanh";
1154 static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
1156 sys::llvm_fenv_clearexcept();
1158 if (sys::llvm_fenv_testexcept()) {
1159 sys::llvm_fenv_clearexcept();
1163 if (Ty->isFloatTy())
1164 return ConstantFP::get(Ty->getContext(), APFloat((float)V));
1165 if (Ty->isDoubleTy())
1166 return ConstantFP::get(Ty->getContext(), APFloat(V));
1167 llvm_unreachable("Can only constant fold float/double");
1170 static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
1171 double V, double W, Type *Ty) {
1172 sys::llvm_fenv_clearexcept();
1174 if (sys::llvm_fenv_testexcept()) {
1175 sys::llvm_fenv_clearexcept();
1179 if (Ty->isFloatTy())
1180 return ConstantFP::get(Ty->getContext(), APFloat((float)V));
1181 if (Ty->isDoubleTy())
1182 return ConstantFP::get(Ty->getContext(), APFloat(V));
1183 llvm_unreachable("Can only constant fold float/double");
1186 /// ConstantFoldConvertToInt - Attempt to an SSE floating point to integer
1187 /// conversion of a constant floating point. If roundTowardZero is false, the
1188 /// default IEEE rounding is used (toward nearest, ties to even). This matches
1189 /// the behavior of the non-truncating SSE instructions in the default rounding
1190 /// mode. The desired integer type Ty is used to select how many bits are
1191 /// available for the result. Returns null if the conversion cannot be
1192 /// performed, otherwise returns the Constant value resulting from the
1194 static Constant *ConstantFoldConvertToInt(const APFloat &Val,
1195 bool roundTowardZero, Type *Ty) {
1196 // All of these conversion intrinsics form an integer of at most 64bits.
1197 unsigned ResultWidth = cast<IntegerType>(Ty)->getBitWidth();
1198 assert(ResultWidth <= 64 &&
1199 "Can only constant fold conversions to 64 and 32 bit ints");
1202 bool isExact = false;
1203 APFloat::roundingMode mode = roundTowardZero? APFloat::rmTowardZero
1204 : APFloat::rmNearestTiesToEven;
1205 APFloat::opStatus status = Val.convertToInteger(&UIntVal, ResultWidth,
1206 /*isSigned=*/true, mode,
1208 if (status != APFloat::opOK && status != APFloat::opInexact)
1210 return ConstantInt::get(Ty, UIntVal, /*isSigned=*/true);
1213 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
1214 /// with the specified arguments, returning null if unsuccessful.
1216 llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
1217 const TargetLibraryInfo *TLI) {
1218 if (!F->hasName()) return 0;
1219 StringRef Name = F->getName();
1221 Type *Ty = F->getReturnType();
1222 if (Operands.size() == 1) {
1223 if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
1224 if (F->getIntrinsicID() == Intrinsic::convert_to_fp16) {
1225 APFloat Val(Op->getValueAPF());
1228 Val.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &lost);
1230 return ConstantInt::get(F->getContext(), Val.bitcastToAPInt());
1235 if (!Ty->isFloatTy() && !Ty->isDoubleTy())
1238 /// We only fold functions with finite arguments. Folding NaN and inf is
1239 /// likely to be aborted with an exception anyway, and some host libms
1240 /// have known errors raising exceptions.
1241 if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity())
1244 /// Currently APFloat versions of these functions do not exist, so we use
1245 /// the host native double versions. Float versions are not called
1246 /// directly but for all these it is true (float)(f((double)arg)) ==
1247 /// f(arg). Long double not supported yet.
1248 double V = Ty->isFloatTy() ? (double)Op->getValueAPF().convertToFloat() :
1249 Op->getValueAPF().convertToDouble();
1252 if (Name == "acos" && TLI->has(LibFunc::acos))
1253 return ConstantFoldFP(acos, V, Ty);
1254 else if (Name == "asin" && TLI->has(LibFunc::asin))
1255 return ConstantFoldFP(asin, V, Ty);
1256 else if (Name == "atan" && TLI->has(LibFunc::atan))
1257 return ConstantFoldFP(atan, V, Ty);
1260 if (Name == "ceil" && TLI->has(LibFunc::ceil))
1261 return ConstantFoldFP(ceil, V, Ty);
1262 else if (Name == "cos" && TLI->has(LibFunc::cos))
1263 return ConstantFoldFP(cos, V, Ty);
1264 else if (Name == "cosh" && TLI->has(LibFunc::cosh))
1265 return ConstantFoldFP(cosh, V, Ty);
1266 else if (Name == "cosf" && TLI->has(LibFunc::cosf))
1267 return ConstantFoldFP(cos, V, Ty);
1270 if (Name == "exp" && TLI->has(LibFunc::exp))
1271 return ConstantFoldFP(exp, V, Ty);
1273 if (Name == "exp2" && TLI->has(LibFunc::exp2)) {
1274 // Constant fold exp2(x) as pow(2,x) in case the host doesn't have a
1276 return ConstantFoldBinaryFP(pow, 2.0, V, Ty);
1280 if (Name == "fabs" && TLI->has(LibFunc::fabs))
1281 return ConstantFoldFP(fabs, V, Ty);
1282 else if (Name == "floor" && TLI->has(LibFunc::floor))
1283 return ConstantFoldFP(floor, V, Ty);
1286 if (Name == "log" && V > 0 && TLI->has(LibFunc::log))
1287 return ConstantFoldFP(log, V, Ty);
1288 else if (Name == "log10" && V > 0 && TLI->has(LibFunc::log10))
1289 return ConstantFoldFP(log10, V, Ty);
1290 else if (F->getIntrinsicID() == Intrinsic::sqrt &&
1291 (Ty->isFloatTy() || Ty->isDoubleTy())) {
1293 return ConstantFoldFP(sqrt, V, Ty);
1295 return Constant::getNullValue(Ty);
1299 if (Name == "sin" && TLI->has(LibFunc::sin))
1300 return ConstantFoldFP(sin, V, Ty);
1301 else if (Name == "sinh" && TLI->has(LibFunc::sinh))
1302 return ConstantFoldFP(sinh, V, Ty);
1303 else if (Name == "sqrt" && V >= 0 && TLI->has(LibFunc::sqrt))
1304 return ConstantFoldFP(sqrt, V, Ty);
1305 else if (Name == "sqrtf" && V >= 0 && TLI->has(LibFunc::sqrtf))
1306 return ConstantFoldFP(sqrt, V, Ty);
1307 else if (Name == "sinf" && TLI->has(LibFunc::sinf))
1308 return ConstantFoldFP(sin, V, Ty);
1311 if (Name == "tan" && TLI->has(LibFunc::tan))
1312 return ConstantFoldFP(tan, V, Ty);
1313 else if (Name == "tanh" && TLI->has(LibFunc::tanh))
1314 return ConstantFoldFP(tanh, V, Ty);
1322 if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
1323 switch (F->getIntrinsicID()) {
1324 case Intrinsic::bswap:
1325 return ConstantInt::get(F->getContext(), Op->getValue().byteSwap());
1326 case Intrinsic::ctpop:
1327 return ConstantInt::get(Ty, Op->getValue().countPopulation());
1328 case Intrinsic::convert_from_fp16: {
1329 APFloat Val(Op->getValue());
1332 APFloat::opStatus status =
1333 Val.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, &lost);
1335 // Conversion is always precise.
1337 assert(status == APFloat::opOK && !lost &&
1338 "Precision lost during fp16 constfolding");
1340 return ConstantFP::get(F->getContext(), Val);
1347 // Support ConstantVector in case we have an Undef in the top.
1348 if (isa<ConstantVector>(Operands[0]) ||
1349 isa<ConstantDataVector>(Operands[0])) {
1350 Constant *Op = cast<Constant>(Operands[0]);
1351 switch (F->getIntrinsicID()) {
1353 case Intrinsic::x86_sse_cvtss2si:
1354 case Intrinsic::x86_sse_cvtss2si64:
1355 case Intrinsic::x86_sse2_cvtsd2si:
1356 case Intrinsic::x86_sse2_cvtsd2si64:
1357 if (ConstantFP *FPOp =
1358 dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
1359 return ConstantFoldConvertToInt(FPOp->getValueAPF(),
1360 /*roundTowardZero=*/false, Ty);
1361 case Intrinsic::x86_sse_cvttss2si:
1362 case Intrinsic::x86_sse_cvttss2si64:
1363 case Intrinsic::x86_sse2_cvttsd2si:
1364 case Intrinsic::x86_sse2_cvttsd2si64:
1365 if (ConstantFP *FPOp =
1366 dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
1367 return ConstantFoldConvertToInt(FPOp->getValueAPF(),
1368 /*roundTowardZero=*/true, Ty);
1372 if (isa<UndefValue>(Operands[0])) {
1373 if (F->getIntrinsicID() == Intrinsic::bswap)
1381 if (Operands.size() == 2) {
1382 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
1383 if (!Ty->isFloatTy() && !Ty->isDoubleTy())
1385 double Op1V = Ty->isFloatTy() ?
1386 (double)Op1->getValueAPF().convertToFloat() :
1387 Op1->getValueAPF().convertToDouble();
1388 if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
1389 if (Op2->getType() != Op1->getType())
1392 double Op2V = Ty->isFloatTy() ?
1393 (double)Op2->getValueAPF().convertToFloat():
1394 Op2->getValueAPF().convertToDouble();
1396 if (F->getIntrinsicID() == Intrinsic::pow) {
1397 return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
1401 if (Name == "pow" && TLI->has(LibFunc::pow))
1402 return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
1403 if (Name == "fmod" && TLI->has(LibFunc::fmod))
1404 return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty);
1405 if (Name == "atan2" && TLI->has(LibFunc::atan2))
1406 return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
1407 } else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
1408 if (F->getIntrinsicID() == Intrinsic::powi && Ty->isFloatTy())
1409 return ConstantFP::get(F->getContext(),
1410 APFloat((float)std::pow((float)Op1V,
1411 (int)Op2C->getZExtValue())));
1412 if (F->getIntrinsicID() == Intrinsic::powi && Ty->isDoubleTy())
1413 return ConstantFP::get(F->getContext(),
1414 APFloat((double)std::pow((double)Op1V,
1415 (int)Op2C->getZExtValue())));
1420 if (ConstantInt *Op1 = dyn_cast<ConstantInt>(Operands[0])) {
1421 if (ConstantInt *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
1422 switch (F->getIntrinsicID()) {
1424 case Intrinsic::sadd_with_overflow:
1425 case Intrinsic::uadd_with_overflow:
1426 case Intrinsic::ssub_with_overflow:
1427 case Intrinsic::usub_with_overflow:
1428 case Intrinsic::smul_with_overflow:
1429 case Intrinsic::umul_with_overflow: {
1432 switch (F->getIntrinsicID()) {
1433 default: llvm_unreachable("Invalid case");
1434 case Intrinsic::sadd_with_overflow:
1435 Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow);
1437 case Intrinsic::uadd_with_overflow:
1438 Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow);
1440 case Intrinsic::ssub_with_overflow:
1441 Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow);
1443 case Intrinsic::usub_with_overflow:
1444 Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow);
1446 case Intrinsic::smul_with_overflow:
1447 Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow);
1449 case Intrinsic::umul_with_overflow:
1450 Res = Op1->getValue().umul_ov(Op2->getValue(), Overflow);
1454 ConstantInt::get(F->getContext(), Res),
1455 ConstantInt::get(Type::getInt1Ty(F->getContext()), Overflow)
1457 return ConstantStruct::get(cast<StructType>(F->getReturnType()), Ops);
1459 case Intrinsic::cttz:
1460 // FIXME: This should check for Op2 == 1, and become unreachable if
1462 return ConstantInt::get(Ty, Op1->getValue().countTrailingZeros());
1463 case Intrinsic::ctlz:
1464 // FIXME: This should check for Op2 == 1, and become unreachable if
1466 return ConstantInt::get(Ty, Op1->getValue().countLeadingZeros());