-//===-- ConstantFolding.cpp - Analyze constant folding possibilities ------===//
+//===-- ConstantFolding.cpp - Fold instructions into constants ------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
//
-// This family of functions determines the possibility of performing constant
-// folding.
+// This file defines routines for folding instructions into constants.
+//
+// Also, to supplement the basic VMCore ConstantExpr simplifications,
+// this file defines some additional folding routines that can make use of
+// TargetData information. These functions cannot go in VMCore due to library
+// dependency issues.
//
//===----------------------------------------------------------------------===//
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
-#include "llvm/LLVMContext.h"
+#include "llvm/Operator.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
-#include "llvm/Target/TargetData.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/FEnv.h"
#include <cerrno>
#include <cmath>
using namespace llvm;
// Constant Folding internal helper functions
//===----------------------------------------------------------------------===//
+/// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
+/// TargetData. This always returns a non-null constant, but it may be a
+/// ConstantExpr if unfoldable.
+static Constant *FoldBitCast(Constant *C, const Type *DestTy,
+ const TargetData &TD) {
+
+ // This only handles casts to vectors currently.
+ const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
+ if (DestVTy == 0)
+ return ConstantExpr::getBitCast(C, DestTy);
+
+ // If this is a scalar -> vector cast, convert the input into a <1 x scalar>
+ // vector so the code below can handle it uniformly.
+ if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) {
+ Constant *Ops = C; // don't take the address of C!
+ return FoldBitCast(ConstantVector::get(Ops), DestTy, TD);
+ }
+
+ // If this is a bitcast from constant vector -> vector, fold it.
+ ConstantVector *CV = dyn_cast<ConstantVector>(C);
+ if (CV == 0)
+ return ConstantExpr::getBitCast(C, DestTy);
+
+ // If the element types match, VMCore can fold it.
+ unsigned NumDstElt = DestVTy->getNumElements();
+ unsigned NumSrcElt = CV->getNumOperands();
+ if (NumDstElt == NumSrcElt)
+ return ConstantExpr::getBitCast(C, DestTy);
+
+ const Type *SrcEltTy = CV->getType()->getElementType();
+ const Type *DstEltTy = DestVTy->getElementType();
+
+ // Otherwise, we're changing the number of elements in a vector, which
+ // requires endianness information to do the right thing. For example,
+ // bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
+ // folds to (little endian):
+ // <4 x i32> <i32 0, i32 0, i32 1, i32 0>
+ // and to (big endian):
+ // <4 x i32> <i32 0, i32 0, i32 0, i32 1>
+
+ // First thing is first. We only want to think about integer here, so if
+ // we have something in FP form, recast it as integer.
+ if (DstEltTy->isFloatingPointTy()) {
+ // Fold to an vector of integers with same size as our FP type.
+ unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
+ const Type *DestIVTy =
+ VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt);
+ // Recursively handle this integer conversion, if possible.
+ C = FoldBitCast(C, DestIVTy, TD);
+ if (!C) return ConstantExpr::getBitCast(C, DestTy);
+
+ // Finally, VMCore can handle this now that #elts line up.
+ return ConstantExpr::getBitCast(C, DestTy);
+ }
+
+ // Okay, we know the destination is integer, if the input is FP, convert
+ // it to integer first.
+ if (SrcEltTy->isFloatingPointTy()) {
+ unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
+ const Type *SrcIVTy =
+ VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
+ // Ask VMCore to do the conversion now that #elts line up.
+ C = ConstantExpr::getBitCast(C, SrcIVTy);
+ CV = dyn_cast<ConstantVector>(C);
+ if (!CV) // If VMCore wasn't able to fold it, bail out.
+ return C;
+ }
+
+ // Now we know that the input and output vectors are both integer vectors
+ // of the same size, and that their #elements is not the same. Do the
+ // conversion here, which depends on whether the input or output has
+ // more elements.
+ bool isLittleEndian = TD.isLittleEndian();
+
+ SmallVector<Constant*, 32> Result;
+ if (NumDstElt < NumSrcElt) {
+ // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
+ Constant *Zero = Constant::getNullValue(DstEltTy);
+ unsigned Ratio = NumSrcElt/NumDstElt;
+ unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
+ unsigned SrcElt = 0;
+ for (unsigned i = 0; i != NumDstElt; ++i) {
+ // Build each element of the result.
+ Constant *Elt = Zero;
+ unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
+ for (unsigned j = 0; j != Ratio; ++j) {
+ Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
+ if (!Src) // Reject constantexpr elements.
+ return ConstantExpr::getBitCast(C, DestTy);
+
+ // Zero extend the element to the right size.
+ Src = ConstantExpr::getZExt(Src, Elt->getType());
+
+ // Shift it to the right place, depending on endianness.
+ Src = ConstantExpr::getShl(Src,
+ ConstantInt::get(Src->getType(), ShiftAmt));
+ ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
+
+ // Mix it in.
+ Elt = ConstantExpr::getOr(Elt, Src);
+ }
+ Result.push_back(Elt);
+ }
+ } else {
+ // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
+ unsigned Ratio = NumDstElt/NumSrcElt;
+ unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
+
+ // Loop over each source value, expanding into multiple results.
+ for (unsigned i = 0; i != NumSrcElt; ++i) {
+ Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
+ if (!Src) // Reject constantexpr elements.
+ return ConstantExpr::getBitCast(C, DestTy);
+
+ unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
+ for (unsigned j = 0; j != Ratio; ++j) {
+ // Shift the piece of the value into the right place, depending on
+ // endianness.
+ Constant *Elt = ConstantExpr::getLShr(Src,
+ ConstantInt::get(Src->getType(), ShiftAmt));
+ ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
+
+ // Truncate and remember this piece.
+ Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
+ }
+ }
+ }
+
+ return ConstantVector::get(Result);
+}
+
+
/// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
/// from a global, return the global and the constant. Because of
/// constantexprs, this function is recursive.
i != e; ++i, ++GTI) {
ConstantInt *CI = dyn_cast<ConstantInt>(*i);
if (!CI) return false; // Index isn't a simple constant?
- if (CI->getZExtValue() == 0) continue; // Not adding anything.
+ if (CI->isZero()) continue; // Not adding anything.
if (const StructType *ST = dyn_cast<StructType>(*GTI)) {
// N = N + Offset
return false;
}
+/// ReadDataFromGlobal - Recursive helper to read bits out of global. C is the
+/// constant being copied out of. ByteOffset is an offset into C. CurPtr is the
+/// pointer to copy results into and BytesLeft is the number of bytes left in
+/// the CurPtr buffer. TD is the target data.
+static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
+ unsigned char *CurPtr, unsigned BytesLeft,
+ const TargetData &TD) {
+ assert(ByteOffset <= TD.getTypeAllocSize(C->getType()) &&
+ "Out of range access");
+
+ // If this element is zero or undefined, we can just return since *CurPtr is
+ // zero initialized.
+ if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C))
+ return true;
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
+ if (CI->getBitWidth() > 64 ||
+ (CI->getBitWidth() & 7) != 0)
+ return false;
+
+ uint64_t Val = CI->getZExtValue();
+ unsigned IntBytes = unsigned(CI->getBitWidth()/8);
+
+ for (unsigned i = 0; i != BytesLeft && ByteOffset != IntBytes; ++i) {
+ CurPtr[i] = (unsigned char)(Val >> (ByteOffset * 8));
+ ++ByteOffset;
+ }
+ return true;
+ }
+
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
+ if (CFP->getType()->isDoubleTy()) {
+ C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), TD);
+ return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
+ }
+ if (CFP->getType()->isFloatTy()){
+ C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD);
+ return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD);
+ }
+ return false;
+ }
+
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
+ const StructLayout *SL = TD.getStructLayout(CS->getType());
+ unsigned Index = SL->getElementContainingOffset(ByteOffset);
+ uint64_t CurEltOffset = SL->getElementOffset(Index);
+ ByteOffset -= CurEltOffset;
+
+ while (1) {
+ // If the element access is to the element itself and not to tail padding,
+ // read the bytes from the element.
+ uint64_t EltSize = TD.getTypeAllocSize(CS->getOperand(Index)->getType());
+
+ if (ByteOffset < EltSize &&
+ !ReadDataFromGlobal(CS->getOperand(Index), ByteOffset, CurPtr,
+ BytesLeft, TD))
+ return false;
+
+ ++Index;
+
+ // Check to see if we read from the last struct element, if so we're done.
+ if (Index == CS->getType()->getNumElements())
+ return true;
+
+ // If we read all of the bytes we needed from this element we're done.
+ uint64_t NextEltOffset = SL->getElementOffset(Index);
+
+ if (BytesLeft <= NextEltOffset-CurEltOffset-ByteOffset)
+ return true;
+
+ // Move to the next element of the struct.
+ CurPtr += NextEltOffset-CurEltOffset-ByteOffset;
+ BytesLeft -= NextEltOffset-CurEltOffset-ByteOffset;
+ ByteOffset = 0;
+ CurEltOffset = NextEltOffset;
+ }
+ // not reached.
+ }
+
+ if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
+ uint64_t EltSize = TD.getTypeAllocSize(CA->getType()->getElementType());
+ uint64_t Index = ByteOffset / EltSize;
+ uint64_t Offset = ByteOffset - Index * EltSize;
+ for (; Index != CA->getType()->getNumElements(); ++Index) {
+ if (!ReadDataFromGlobal(CA->getOperand(Index), Offset, CurPtr,
+ BytesLeft, TD))
+ return false;
+ if (EltSize >= BytesLeft)
+ return true;
+
+ Offset = 0;
+ BytesLeft -= EltSize;
+ CurPtr += EltSize;
+ }
+ return true;
+ }
+
+ if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) {
+ uint64_t EltSize = TD.getTypeAllocSize(CV->getType()->getElementType());
+ uint64_t Index = ByteOffset / EltSize;
+ uint64_t Offset = ByteOffset - Index * EltSize;
+ for (; Index != CV->getType()->getNumElements(); ++Index) {
+ if (!ReadDataFromGlobal(CV->getOperand(Index), Offset, CurPtr,
+ BytesLeft, TD))
+ return false;
+ if (EltSize >= BytesLeft)
+ return true;
+
+ Offset = 0;
+ BytesLeft -= EltSize;
+ CurPtr += EltSize;
+ }
+ return true;
+ }
+
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
+ if (CE->getOpcode() == Instruction::IntToPtr &&
+ CE->getOperand(0)->getType() == TD.getIntPtrType(CE->getContext()))
+ return ReadDataFromGlobal(CE->getOperand(0), ByteOffset, CurPtr,
+ BytesLeft, TD);
+ }
+
+ // Otherwise, unknown initializer type.
+ return false;
+}
+
+static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
+ const TargetData &TD) {
+ const Type *LoadTy = cast<PointerType>(C->getType())->getElementType();
+ const IntegerType *IntType = dyn_cast<IntegerType>(LoadTy);
+
+ // If this isn't an integer load we can't fold it directly.
+ if (!IntType) {
+ // If this is a float/double load, we can try folding it as an int32/64 load
+ // and then bitcast the result. This can be useful for union cases. Note
+ // that address spaces don't matter here since we're not going to result in
+ // an actual new load.
+ const Type *MapTy;
+ if (LoadTy->isFloatTy())
+ MapTy = Type::getInt32PtrTy(C->getContext());
+ else if (LoadTy->isDoubleTy())
+ MapTy = Type::getInt64PtrTy(C->getContext());
+ else if (LoadTy->isVectorTy()) {
+ MapTy = IntegerType::get(C->getContext(),
+ TD.getTypeAllocSizeInBits(LoadTy));
+ MapTy = PointerType::getUnqual(MapTy);
+ } else
+ return 0;
+
+ C = FoldBitCast(C, MapTy, TD);
+ if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD))
+ return FoldBitCast(Res, LoadTy, TD);
+ return 0;
+ }
+
+ unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
+ if (BytesLoaded > 32 || BytesLoaded == 0) return 0;
+
+ GlobalValue *GVal;
+ int64_t Offset;
+ if (!IsConstantOffsetFromGlobal(C, GVal, Offset, TD))
+ return 0;
+
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(GVal);
+ if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
+ !GV->getInitializer()->getType()->isSized())
+ return 0;
+
+ // If we're loading off the beginning of the global, some bytes may be valid,
+ // but we don't try to handle this.
+ if (Offset < 0) return 0;
+
+ // If we're not accessing anything in this constant, the result is undefined.
+ if (uint64_t(Offset) >= TD.getTypeAllocSize(GV->getInitializer()->getType()))
+ return UndefValue::get(IntType);
+
+ unsigned char RawBytes[32] = {0};
+ if (!ReadDataFromGlobal(GV->getInitializer(), Offset, RawBytes,
+ BytesLoaded, TD))
+ return 0;
+
+ APInt ResultVal = APInt(IntType->getBitWidth(), RawBytes[BytesLoaded-1]);
+ for (unsigned i = 1; i != BytesLoaded; ++i) {
+ ResultVal <<= 8;
+ ResultVal |= RawBytes[BytesLoaded-1-i];
+ }
+
+ return ConstantInt::get(IntType->getContext(), ResultVal);
+}
+
+/// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
+/// produce if it is constant and determinable. If this is not determinable,
+/// return null.
+Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
+ const TargetData *TD) {
+ // First, try the easy cases:
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer())
+ return GV->getInitializer();
+
+ // If the loaded value isn't a constant expr, we can't handle it.
+ ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
+ if (!CE) return 0;
+
+ if (CE->getOpcode() == Instruction::GetElementPtr) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer())
+ if (Constant *V =
+ ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
+ return V;
+ }
+
+ // Instead of loading constant c string, use corresponding integer value
+ // directly if string length is small enough.
+ std::string Str;
+ if (TD && GetConstantStringInfo(CE, Str) && !Str.empty()) {
+ unsigned StrLen = Str.length();
+ const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
+ unsigned NumBits = Ty->getPrimitiveSizeInBits();
+ // Replace load with immediate integer if the result is an integer or fp
+ // value.
+ if ((NumBits >> 3) == StrLen + 1 && (NumBits & 7) == 0 &&
+ (isa<IntegerType>(Ty) || Ty->isFloatingPointTy())) {
+ APInt StrVal(NumBits, 0);
+ APInt SingleChar(NumBits, 0);
+ if (TD->isLittleEndian()) {
+ for (signed i = StrLen-1; i >= 0; i--) {
+ SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+ StrVal = (StrVal << 8) | SingleChar;
+ }
+ } else {
+ for (unsigned i = 0; i < StrLen; i++) {
+ SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+ StrVal = (StrVal << 8) | SingleChar;
+ }
+ // Append NULL at the end.
+ SingleChar = 0;
+ StrVal = (StrVal << 8) | SingleChar;
+ }
+
+ Constant *Res = ConstantInt::get(CE->getContext(), StrVal);
+ if (Ty->isFloatingPointTy())
+ Res = ConstantExpr::getBitCast(Res, Ty);
+ return Res;
+ }
+ }
+
+ // If this load comes from anywhere in a constant global, and if the global
+ // is all undef or zero, we know what it loads.
+ if (GlobalVariable *GV =
+ dyn_cast<GlobalVariable>(GetUnderlyingObject(CE, TD))) {
+ if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
+ const Type *ResTy = cast<PointerType>(C->getType())->getElementType();
+ if (GV->getInitializer()->isNullValue())
+ return Constant::getNullValue(ResTy);
+ if (isa<UndefValue>(GV->getInitializer()))
+ return UndefValue::get(ResTy);
+ }
+ }
+
+ // Try hard to fold loads from bitcasted strange and non-type-safe things. We
+ // currently don't do any of this for big endian systems. It can be
+ // generalized in the future if someone is interested.
+ if (TD && TD->isLittleEndian())
+ return FoldReinterpretLoadFromConstPtr(CE, *TD);
+ return 0;
+}
+
+static Constant *ConstantFoldLoadInst(const LoadInst *LI, const TargetData *TD){
+ if (LI->isVolatile()) return 0;
+
+ if (Constant *C = dyn_cast<Constant>(LI->getOperand(0)))
+ return ConstantFoldLoadFromConstPtr(C, TD);
+
+ return 0;
+}
/// SymbolicallyEvaluateBinop - One of Op0/Op1 is a constant expression.
/// Attempt to symbolically evaluate the result of a binary operator merging
/// these together. If target data info is available, it is provided as TD,
/// otherwise TD is null.
static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0,
- Constant *Op1, const TargetData *TD,
- LLVMContext &Context){
+ Constant *Op1, const TargetData *TD){
// SROA
// Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
return 0;
}
+/// CastGEPIndices - If array indices are not pointer-sized integers,
+/// explicitly cast them so that they aren't implicitly casted by the
+/// getelementptr.
+static Constant *CastGEPIndices(Constant *const *Ops, unsigned NumOps,
+ const Type *ResultTy,
+ const TargetData *TD) {
+ if (!TD) return 0;
+ const Type *IntPtrTy = TD->getIntPtrType(ResultTy->getContext());
+
+ bool Any = false;
+ SmallVector<Constant*, 32> NewIdxs;
+ for (unsigned i = 1; i != NumOps; ++i) {
+ if ((i == 1 ||
+ !isa<StructType>(GetElementPtrInst::getIndexedType(Ops[0]->getType(),
+ reinterpret_cast<Value *const *>(Ops+1),
+ i-1))) &&
+ Ops[i]->getType() != IntPtrTy) {
+ Any = true;
+ NewIdxs.push_back(ConstantExpr::getCast(CastInst::getCastOpcode(Ops[i],
+ true,
+ IntPtrTy,
+ true),
+ Ops[i], IntPtrTy));
+ } else
+ NewIdxs.push_back(Ops[i]);
+ }
+ if (!Any) return 0;
+
+ Constant *C =
+ ConstantExpr::getGetElementPtr(Ops[0], &NewIdxs[0], NewIdxs.size());
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
+ if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
+ C = Folded;
+ return C;
+}
+
/// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
/// constant expression, do so.
-static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
+static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
const Type *ResultTy,
- LLVMContext &Context,
const TargetData *TD) {
Constant *Ptr = Ops[0];
if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()->isSized())
return 0;
-
- unsigned BitWidth = TD->getTypeSizeInBits(TD->getIntPtrType(Context));
- APInt BasePtr(BitWidth, 0);
- bool BaseIsInt = true;
- if (!Ptr->isNullValue()) {
- // If this is a inttoptr from a constant int, we can fold this as the base,
- // otherwise we can't.
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
- if (CE->getOpcode() == Instruction::IntToPtr)
- if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
- BasePtr = Base->getValue();
-
- if (BasePtr == 0)
- BaseIsInt = false;
- }
+
+ const Type *IntPtrTy = TD->getIntPtrType(Ptr->getContext());
// If this is a constant expr gep that is effectively computing an
// "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12'
for (unsigned i = 1; i != NumOps; ++i)
- if (!isa<ConstantInt>(Ops[i]))
+ if (!isa<ConstantInt>(Ops[i])) {
+
+ // If this is "gep i8* Ptr, (sub 0, V)", fold this as:
+ // "inttoptr (sub (ptrtoint Ptr), V)"
+ if (NumOps == 2 &&
+ cast<PointerType>(ResultTy)->getElementType()->isIntegerTy(8)) {
+ ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[1]);
+ assert((CE == 0 || CE->getType() == IntPtrTy) &&
+ "CastGEPIndices didn't canonicalize index types!");
+ if (CE && CE->getOpcode() == Instruction::Sub &&
+ CE->getOperand(0)->isNullValue()) {
+ Constant *Res = ConstantExpr::getPtrToInt(Ptr, CE->getType());
+ Res = ConstantExpr::getSub(Res, CE->getOperand(1));
+ Res = ConstantExpr::getIntToPtr(Res, ResultTy);
+ if (ConstantExpr *ResCE = dyn_cast<ConstantExpr>(Res))
+ Res = ConstantFoldConstantExpression(ResCE, TD);
+ return Res;
+ }
+ }
return 0;
+ }
+ unsigned BitWidth = TD->getTypeSizeInBits(IntPtrTy);
APInt Offset = APInt(BitWidth,
TD->getIndexedOffset(Ptr->getType(),
(Value**)Ops+1, NumOps-1));
+ Ptr = cast<Constant>(Ptr->stripPointerCasts());
+
+ // If this is a GEP of a GEP, fold it all into a single GEP.
+ while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
+ SmallVector<Value *, 4> NestedOps(GEP->op_begin()+1, GEP->op_end());
+
+ // Do not try the incorporate the sub-GEP if some index is not a number.
+ bool AllConstantInt = true;
+ for (unsigned i = 0, e = NestedOps.size(); i != e; ++i)
+ if (!isa<ConstantInt>(NestedOps[i])) {
+ AllConstantInt = false;
+ break;
+ }
+ if (!AllConstantInt)
+ break;
+
+ Ptr = cast<Constant>(GEP->getOperand(0));
+ Offset += APInt(BitWidth,
+ TD->getIndexedOffset(Ptr->getType(),
+ (Value**)NestedOps.data(),
+ NestedOps.size()));
+ Ptr = cast<Constant>(Ptr->stripPointerCasts());
+ }
+
// If the base value for this address is a literal integer value, fold the
// getelementptr to the resulting integer value casted to the pointer type.
- if (BaseIsInt) {
- Constant *C = ConstantInt::get(Context, Offset+BasePtr);
+ APInt BasePtr(BitWidth, 0);
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ if (CE->getOpcode() == Instruction::IntToPtr)
+ if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
+ BasePtr = Base->getValue().zextOrTrunc(BitWidth);
+ if (Ptr->isNullValue() || BasePtr != 0) {
+ Constant *C = ConstantInt::get(Ptr->getContext(), Offset+BasePtr);
return ConstantExpr::getIntToPtr(C, ResultTy);
}
SmallVector<Constant*, 32> NewIdxs;
do {
if (const SequentialType *ATy = dyn_cast<SequentialType>(Ty)) {
- // The only pointer indexing we'll do is on the first index of the GEP.
- if (isa<PointerType>(ATy) && ATy != Ptr->getType())
- break;
+ if (ATy->isPointerTy()) {
+ // The only pointer indexing we'll do is on the first index of the GEP.
+ if (!NewIdxs.empty())
+ break;
+
+ // Only handle pointers to sized types, not pointers to functions.
+ if (!ATy->getElementType()->isSized())
+ return 0;
+ }
+
// Determine which element of the array the offset points into.
APInt ElemSize(BitWidth, TD->getTypeAllocSize(ATy->getElementType()));
+ const IntegerType *IntPtrTy = TD->getIntPtrType(Ty->getContext());
if (ElemSize == 0)
- return 0;
- APInt NewIdx = Offset.udiv(ElemSize);
- Offset -= NewIdx * ElemSize;
- NewIdxs.push_back(ConstantInt::get(TD->getIntPtrType(Context), NewIdx));
+ // The element size is 0. This may be [0 x Ty]*, so just use a zero
+ // index for this level and proceed to the next level to see if it can
+ // accommodate the offset.
+ NewIdxs.push_back(ConstantInt::get(IntPtrTy, 0));
+ else {
+ // The element size is non-zero divide the offset by the element
+ // size (rounding down), to compute the index at this level.
+ APInt NewIdx = Offset.udiv(ElemSize);
+ Offset -= NewIdx * ElemSize;
+ NewIdxs.push_back(ConstantInt::get(IntPtrTy, NewIdx));
+ }
Ty = ATy->getElementType();
} else if (const StructType *STy = dyn_cast<StructType>(Ty)) {
// Determine which field of the struct the offset points into. The
// know the offset is within the struct at this point.
const StructLayout &SL = *TD->getStructLayout(STy);
unsigned ElIdx = SL.getElementContainingOffset(Offset.getZExtValue());
- NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), ElIdx));
+ NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
+ ElIdx));
Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx));
Ty = STy->getTypeAtIndex(ElIdx);
} else {
if (Offset != 0)
return 0;
- // If the base is the start of a GlobalVariable and all the array indices
- // remain in their static bounds, the GEP is inbounds. We can check that
- // all indices are in bounds by just checking the first index only
- // because we've just normalized all the indices.
- Constant *C = isa<GlobalVariable>(Ptr) && NewIdxs[0]->isNullValue() ?
- ConstantExpr::getInBoundsGetElementPtr(Ptr, &NewIdxs[0], NewIdxs.size()) :
+ // Create a GEP.
+ Constant *C =
ConstantExpr::getGetElementPtr(Ptr, &NewIdxs[0], NewIdxs.size());
assert(cast<PointerType>(C->getType())->getElementType() == Ty &&
"Computed GetElementPtr has unexpected type!");
// If we ended up indexing a member with a type that doesn't match
// the type of what the original indices indexed, add a cast.
if (Ty != cast<PointerType>(ResultTy)->getElementType())
- C = ConstantExpr::getBitCast(C, ResultTy);
+ C = FoldBitCast(C, ResultTy, *TD);
return C;
}
-/// FoldBitCast - Constant fold bitcast, symbolically evaluating it with
-/// targetdata. Return 0 if unfoldable.
-static Constant *FoldBitCast(Constant *C, const Type *DestTy,
- const TargetData &TD, LLVMContext &Context) {
- // If this is a bitcast from constant vector -> vector, fold it.
- if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) {
- if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
- // If the element types match, VMCore can fold it.
- unsigned NumDstElt = DestVTy->getNumElements();
- unsigned NumSrcElt = CV->getNumOperands();
- if (NumDstElt == NumSrcElt)
- return 0;
-
- const Type *SrcEltTy = CV->getType()->getElementType();
- const Type *DstEltTy = DestVTy->getElementType();
-
- // Otherwise, we're changing the number of elements in a vector, which
- // requires endianness information to do the right thing. For example,
- // bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
- // folds to (little endian):
- // <4 x i32> <i32 0, i32 0, i32 1, i32 0>
- // and to (big endian):
- // <4 x i32> <i32 0, i32 0, i32 0, i32 1>
-
- // First thing is first. We only want to think about integer here, so if
- // we have something in FP form, recast it as integer.
- if (DstEltTy->isFloatingPoint()) {
- // Fold to an vector of integers with same size as our FP type.
- unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
- const Type *DestIVTy = VectorType::get(
- IntegerType::get(Context, FPWidth), NumDstElt);
- // Recursively handle this integer conversion, if possible.
- C = FoldBitCast(C, DestIVTy, TD, Context);
- if (!C) return 0;
-
- // Finally, VMCore can handle this now that #elts line up.
- return ConstantExpr::getBitCast(C, DestTy);
- }
-
- // Okay, we know the destination is integer, if the input is FP, convert
- // it to integer first.
- if (SrcEltTy->isFloatingPoint()) {
- unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
- const Type *SrcIVTy = VectorType::get(
- IntegerType::get(Context, FPWidth), NumSrcElt);
- // Ask VMCore to do the conversion now that #elts line up.
- C = ConstantExpr::getBitCast(C, SrcIVTy);
- CV = dyn_cast<ConstantVector>(C);
- if (!CV) return 0; // If VMCore wasn't able to fold it, bail out.
- }
-
- // Now we know that the input and output vectors are both integer vectors
- // of the same size, and that their #elements is not the same. Do the
- // conversion here, which depends on whether the input or output has
- // more elements.
- bool isLittleEndian = TD.isLittleEndian();
-
- SmallVector<Constant*, 32> Result;
- if (NumDstElt < NumSrcElt) {
- // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
- Constant *Zero = Constant::getNullValue(DstEltTy);
- unsigned Ratio = NumSrcElt/NumDstElt;
- unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
- unsigned SrcElt = 0;
- for (unsigned i = 0; i != NumDstElt; ++i) {
- // Build each element of the result.
- Constant *Elt = Zero;
- unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
- for (unsigned j = 0; j != Ratio; ++j) {
- Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++));
- if (!Src) return 0; // Reject constantexpr elements.
-
- // Zero extend the element to the right size.
- Src = ConstantExpr::getZExt(Src, Elt->getType());
-
- // Shift it to the right place, depending on endianness.
- Src = ConstantExpr::getShl(Src,
- ConstantInt::get(Src->getType(), ShiftAmt));
- ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
-
- // Mix it in.
- Elt = ConstantExpr::getOr(Elt, Src);
- }
- Result.push_back(Elt);
- }
- } else {
- // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
- unsigned Ratio = NumDstElt/NumSrcElt;
- unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
-
- // Loop over each source value, expanding into multiple results.
- for (unsigned i = 0; i != NumSrcElt; ++i) {
- Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i));
- if (!Src) return 0; // Reject constantexpr elements.
-
- unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
- for (unsigned j = 0; j != Ratio; ++j) {
- // Shift the piece of the value into the right place, depending on
- // endianness.
- Constant *Elt = ConstantExpr::getLShr(Src,
- ConstantInt::get(Src->getType(), ShiftAmt));
- ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
-
- // Truncate and remember this piece.
- Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
- }
- }
- }
-
- return ConstantVector::get(Result.data(), Result.size());
- }
- }
-
- return 0;
-}
//===----------------------------------------------------------------------===//
// Constant Folding public APIs
//===----------------------------------------------------------------------===//
-
-/// ConstantFoldInstruction - Attempt to constant fold the specified
-/// instruction. If successful, the constant result is returned, if not, null
-/// is returned. Note that this function can only fail when attempting to fold
-/// instructions like loads and stores, which have no constant expression form.
-///
-Constant *llvm::ConstantFoldInstruction(Instruction *I, LLVMContext &Context,
- const TargetData *TD) {
+/// ConstantFoldInstruction - Try to constant fold the specified instruction.
+/// If successful, the constant result is returned, if not, null is returned.
+/// Note that this fails if not all of the operands are constant. Otherwise,
+/// this function can only fail when attempting to fold instructions like loads
+/// and stores, which have no constant expression form.
+Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) {
+ // Handle PHI nodes quickly here...
if (PHINode *PN = dyn_cast<PHINode>(I)) {
- if (PN->getNumIncomingValues() == 0)
- return UndefValue::get(PN->getType());
+ Constant *CommonValue = 0;
- Constant *Result = dyn_cast<Constant>(PN->getIncomingValue(0));
- if (Result == 0) return 0;
-
- // Handle PHI nodes specially here...
- for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
- if (PN->getIncomingValue(i) != Result && PN->getIncomingValue(i) != PN)
- return 0; // Not all the same incoming constants...
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ Value *Incoming = PN->getIncomingValue(i);
+ // If the incoming value is undef then skip it. Note that while we could
+ // skip the value if it is equal to the phi node itself we choose not to
+ // because that would break the rule that constant folding only applies if
+ // all operands are constants.
+ if (isa<UndefValue>(Incoming))
+ continue;
+ // If the incoming value is not a constant, or is a different constant to
+ // the one we saw previously, then give up.
+ Constant *C = dyn_cast<Constant>(Incoming);
+ if (!C || (CommonValue && C != CommonValue))
+ return 0;
+ CommonValue = C;
+ }
- // If we reach here, all incoming values are the same constant.
- return Result;
+ // If we reach here, all incoming values are the same constant or undef.
+ return CommonValue ? CommonValue : UndefValue::get(PN->getType());
}
// Scan the operand list, checking to see if they are all constants, if so,
return 0; // All operands not constant!
if (const CmpInst *CI = dyn_cast<CmpInst>(I))
- return ConstantFoldCompareInstOperands(CI->getPredicate(),
- Ops.data(), Ops.size(),
- Context, TD);
- else
- return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
- Ops.data(), Ops.size(), Context, TD);
+ return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
+ TD);
+
+ if (const LoadInst *LI = dyn_cast<LoadInst>(I))
+ return ConstantFoldLoadInst(LI, TD);
+
+ if (InsertValueInst *IVI = dyn_cast<InsertValueInst>(I))
+ return ConstantExpr::getInsertValue(
+ cast<Constant>(IVI->getAggregateOperand()),
+ cast<Constant>(IVI->getInsertedValueOperand()),
+ IVI->idx_begin(), IVI->getNumIndices());
+
+ if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I))
+ return ConstantExpr::getExtractValue(
+ cast<Constant>(EVI->getAggregateOperand()),
+ EVI->idx_begin(), EVI->getNumIndices());
+
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ Ops.data(), Ops.size(), TD);
}
/// ConstantFoldConstantExpression - Attempt to fold the constant expression
/// using the specified TargetData. If successful, the constant result is
/// result is returned, if not, null is returned.
-Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
- LLVMContext &Context,
+Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
const TargetData *TD) {
SmallVector<Constant*, 8> Ops;
- for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
- Ops.push_back(cast<Constant>(*i));
+ for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end();
+ i != e; ++i) {
+ Constant *NewC = cast<Constant>(*i);
+ // Recursively fold the ConstantExpr's operands.
+ if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC))
+ NewC = ConstantFoldConstantExpression(NewCE, TD);
+ Ops.push_back(NewC);
+ }
if (CE->isCompare())
- return ConstantFoldCompareInstOperands(CE->getPredicate(),
- Ops.data(), Ops.size(),
- Context, TD);
- else
- return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(),
- Ops.data(), Ops.size(), Context, TD);
+ return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
+ TD);
+ return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(),
+ Ops.data(), Ops.size(), TD);
}
/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
/// attempting to fold instructions like loads and stores, which have no
/// constant expression form.
///
+/// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
+/// information, due to only being passed an opcode and operands. Constant
+/// folding using this function strips this information.
+///
Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
Constant* const* Ops, unsigned NumOps,
- LLVMContext &Context,
const TargetData *TD) {
// Handle easy binops first.
if (Instruction::isBinaryOp(Opcode)) {
if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1]))
- if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD,
- Context))
+ if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD))
return C;
return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
switch (Opcode) {
default: return 0;
+ case Instruction::ICmp:
+ case Instruction::FCmp: assert(0 && "Invalid for compares");
case Instruction::Call:
- if (Function *F = dyn_cast<Function>(Ops[0]))
+ if (Function *F = dyn_cast<Function>(Ops[NumOps - 1]))
if (canConstantFoldCallTo(F))
- return ConstantFoldCall(F, Ops+1, NumOps-1);
+ return ConstantFoldCall(F, Ops, NumOps - 1);
return 0;
- case Instruction::ICmp:
- case Instruction::FCmp:
- llvm_unreachable("This function is invalid for compares: no predicate specified");
case Instruction::PtrToInt:
// If the input is a inttoptr, eliminate the pair. This requires knowing
// the width of a pointer, so it can't be done in ConstantExpr::getCast.
unsigned InWidth = Input->getType()->getScalarSizeInBits();
if (TD->getPointerSizeInBits() < InWidth) {
Constant *Mask =
- ConstantInt::get(Context, APInt::getLowBitsSet(InWidth,
+ ConstantInt::get(CE->getContext(), APInt::getLowBitsSet(InWidth,
TD->getPointerSizeInBits()));
Input = ConstantExpr::getAnd(Input, Mask);
}
// If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
// the int size is >= the ptr size. This requires knowing the width of a
// pointer, so it can't be done in ConstantExpr::getCast.
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0]))
if (TD &&
- TD->getPointerSizeInBits() <=
- CE->getType()->getScalarSizeInBits()) {
- if (CE->getOpcode() == Instruction::PtrToInt) {
- Constant *Input = CE->getOperand(0);
- Constant *C = FoldBitCast(Input, DestTy, *TD, Context);
- return C ? C : ConstantExpr::getBitCast(Input, DestTy);
- }
- // If there's a constant offset added to the integer value before
- // it is casted back to a pointer, see if the expression can be
- // converted into a GEP.
- if (CE->getOpcode() == Instruction::Add)
- if (ConstantInt *L = dyn_cast<ConstantInt>(CE->getOperand(0)))
- if (ConstantExpr *R = dyn_cast<ConstantExpr>(CE->getOperand(1)))
- if (R->getOpcode() == Instruction::PtrToInt)
- if (GlobalVariable *GV =
- dyn_cast<GlobalVariable>(R->getOperand(0))) {
- const PointerType *GVTy = cast<PointerType>(GV->getType());
- if (const ArrayType *AT =
- dyn_cast<ArrayType>(GVTy->getElementType())) {
- const Type *ElTy = AT->getElementType();
- uint64_t AllocSize = TD->getTypeAllocSize(ElTy);
- APInt PSA(L->getValue().getBitWidth(), AllocSize);
- if (ElTy == cast<PointerType>(DestTy)->getElementType() &&
- L->getValue().urem(PSA) == 0) {
- APInt ElemIdx = L->getValue().udiv(PSA);
- if (ElemIdx.ult(APInt(ElemIdx.getBitWidth(),
- AT->getNumElements()))) {
- Constant *Index[] = {
- Constant::getNullValue(CE->getType()),
- ConstantInt::get(Context, ElemIdx)
- };
- return
- ConstantExpr::getGetElementPtr(GV, &Index[0], 2);
- }
- }
- }
- }
- }
- }
+ TD->getPointerSizeInBits() <= CE->getType()->getScalarSizeInBits() &&
+ CE->getOpcode() == Instruction::PtrToInt)
+ return FoldBitCast(CE->getOperand(0), DestTy, *TD);
+
return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::Trunc:
case Instruction::ZExt:
return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::BitCast:
if (TD)
- if (Constant *C = FoldBitCast(Ops[0], DestTy, *TD, Context))
- return C;
+ return FoldBitCast(Ops[0], DestTy, *TD);
return ConstantExpr::getBitCast(Ops[0], DestTy);
case Instruction::Select:
return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
case Instruction::ShuffleVector:
return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
case Instruction::GetElementPtr:
- if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, Context, TD))
+ if (Constant *C = CastGEPIndices(Ops, NumOps, DestTy, TD))
+ return C;
+ if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, TD))
return C;
return ConstantExpr::getGetElementPtr(Ops[0], Ops+1, NumOps-1);
/// returns a constant expression of the specified operands.
///
Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
- Constant*const * Ops,
- unsigned NumOps,
- LLVMContext &Context,
+ Constant *Ops0, Constant *Ops1,
const TargetData *TD) {
// fold: icmp (inttoptr x), null -> icmp x, 0
// fold: icmp (ptrtoint x), 0 -> icmp x, null
//
// ConstantExpr::getCompare cannot do this, because it doesn't have TD
// around to know if bit truncation is happening.
- if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops[0])) {
- if (TD && Ops[1]->isNullValue()) {
- const Type *IntPtrTy = TD->getIntPtrType(Context);
+ if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops0)) {
+ if (TD && Ops1->isNullValue()) {
+ const Type *IntPtrTy = TD->getIntPtrType(CE0->getContext());
if (CE0->getOpcode() == Instruction::IntToPtr) {
// Convert the integer value to the right size to ensure we get the
// proper extension or truncation.
Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
IntPtrTy, false);
- Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
- return ConstantFoldCompareInstOperands(Predicate, NewOps, 2,
- Context, TD);
+ Constant *Null = Constant::getNullValue(C->getType());
+ return ConstantFoldCompareInstOperands(Predicate, C, Null, TD);
}
// Only do this transformation if the int is intptrty in size, otherwise
if (CE0->getOpcode() == Instruction::PtrToInt &&
CE0->getType() == IntPtrTy) {
Constant *C = CE0->getOperand(0);
- Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
- // FIXME!
- return ConstantFoldCompareInstOperands(Predicate, NewOps, 2,
- Context, TD);
+ Constant *Null = Constant::getNullValue(C->getType());
+ return ConstantFoldCompareInstOperands(Predicate, C, Null, TD);
}
}
- if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops[1])) {
+ if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops1)) {
if (TD && CE0->getOpcode() == CE1->getOpcode()) {
- const Type *IntPtrTy = TD->getIntPtrType(Context);
+ const Type *IntPtrTy = TD->getIntPtrType(CE0->getContext());
if (CE0->getOpcode() == Instruction::IntToPtr) {
// Convert the integer value to the right size to ensure we get the
IntPtrTy, false);
Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
IntPtrTy, false);
- Constant *NewOps[] = { C0, C1 };
- return ConstantFoldCompareInstOperands(Predicate, NewOps, 2,
- Context, TD);
+ return ConstantFoldCompareInstOperands(Predicate, C0, C1, TD);
}
// Only do this transformation if the int is intptrty in size, otherwise
// there is a truncation or extension that we aren't modeling.
if ((CE0->getOpcode() == Instruction::PtrToInt &&
CE0->getType() == IntPtrTy &&
- CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType())) {
- Constant *NewOps[] = {
- CE0->getOperand(0), CE1->getOperand(0)
- };
- return ConstantFoldCompareInstOperands(Predicate, NewOps, 2,
- Context, TD);
- }
+ CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType()))
+ return ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0),
+ CE1->getOperand(0), TD);
}
}
+
+ // icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0)
+ // icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0)
+ if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) &&
+ CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) {
+ Constant *LHS =
+ ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0), Ops1,TD);
+ Constant *RHS =
+ ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(1), Ops1,TD);
+ unsigned OpC =
+ Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
+ Constant *Ops[] = { LHS, RHS };
+ return ConstantFoldInstOperands(OpC, LHS->getType(), Ops, 2, TD);
+ }
}
- return ConstantExpr::getCompare(Predicate, Ops[0], Ops[1]);
+
+ return ConstantExpr::getCompare(Predicate, Ops0, Ops1);
}
/// getelementptr constantexpr, return the constant value being addressed by the
/// constant expression, or null if something is funny and we can't decide.
Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
- ConstantExpr *CE,
- LLVMContext &Context) {
+ ConstantExpr *CE) {
if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
return 0; // Do not allow stepping over the value!
C = UndefValue::get(ATy->getElementType());
else
return 0;
- } else if (const VectorType *PTy = dyn_cast<VectorType>(*I)) {
- if (CI->getZExtValue() >= PTy->getNumElements())
+ } else if (const VectorType *VTy = dyn_cast<VectorType>(*I)) {
+ if (CI->getZExtValue() >= VTy->getNumElements())
return 0;
if (ConstantVector *CP = dyn_cast<ConstantVector>(C))
C = CP->getOperand(CI->getZExtValue());
else if (isa<ConstantAggregateZero>(C))
- C = Constant::getNullValue(PTy->getElementType());
+ C = Constant::getNullValue(VTy->getElementType());
else if (isa<UndefValue>(C))
- C = UndefValue::get(PTy->getElementType());
+ C = UndefValue::get(VTy->getElementType());
else
return 0;
} else {
case Intrinsic::ctpop:
case Intrinsic::ctlz:
case Intrinsic::cttz:
+ case Intrinsic::sadd_with_overflow:
+ case Intrinsic::uadd_with_overflow:
+ case Intrinsic::ssub_with_overflow:
+ case Intrinsic::usub_with_overflow:
+ case Intrinsic::smul_with_overflow:
+ case Intrinsic::umul_with_overflow:
+ case Intrinsic::convert_from_fp16:
+ case Intrinsic::convert_to_fp16:
+ case Intrinsic::x86_sse_cvtss2si:
+ case Intrinsic::x86_sse_cvtss2si64:
+ case Intrinsic::x86_sse_cvttss2si:
+ case Intrinsic::x86_sse_cvttss2si64:
+ case Intrinsic::x86_sse2_cvtsd2si:
+ case Intrinsic::x86_sse2_cvtsd2si64:
+ case Intrinsic::x86_sse2_cvttsd2si:
+ case Intrinsic::x86_sse2_cvttsd2si64:
return true;
- default: break;
+ default:
+ return false;
+ case 0: break;
}
if (!F->hasName()) return false;
case 'c':
return Name == "cos" || Name == "ceil" || Name == "cosf" || Name == "cosh";
case 'e':
- return Name == "exp";
+ return Name == "exp" || Name == "exp2";
case 'f':
return Name == "fabs" || Name == "fmod" || Name == "floor";
case 'l':
}
static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
- const Type *Ty, LLVMContext &Context) {
- errno = 0;
+ const Type *Ty) {
+ sys::llvm_fenv_clearexcept();
V = NativeFP(V);
- if (errno != 0) {
- errno = 0;
+ if (sys::llvm_fenv_testexcept()) {
+ sys::llvm_fenv_clearexcept();
return 0;
}
- if (Ty == Type::getFloatTy(Context))
- return ConstantFP::get(Context, APFloat((float)V));
- if (Ty == Type::getDoubleTy(Context))
- return ConstantFP::get(Context, APFloat(V));
+ if (Ty->isFloatTy())
+ return ConstantFP::get(Ty->getContext(), APFloat((float)V));
+ if (Ty->isDoubleTy())
+ return ConstantFP::get(Ty->getContext(), APFloat(V));
llvm_unreachable("Can only constant fold float/double");
return 0; // dummy return to suppress warning
}
static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
- double V, double W,
- const Type *Ty,
- LLVMContext &Context) {
- errno = 0;
+ double V, double W, const Type *Ty) {
+ sys::llvm_fenv_clearexcept();
V = NativeFP(V, W);
- if (errno != 0) {
- errno = 0;
+ if (sys::llvm_fenv_testexcept()) {
+ sys::llvm_fenv_clearexcept();
return 0;
}
- if (Ty == Type::getFloatTy(Context))
- return ConstantFP::get(Context, APFloat((float)V));
- if (Ty == Type::getDoubleTy(Context))
- return ConstantFP::get(Context, APFloat(V));
+ if (Ty->isFloatTy())
+ return ConstantFP::get(Ty->getContext(), APFloat((float)V));
+ if (Ty->isDoubleTy())
+ return ConstantFP::get(Ty->getContext(), APFloat(V));
llvm_unreachable("Can only constant fold float/double");
return 0; // dummy return to suppress warning
}
+/// ConstantFoldConvertToInt - Attempt to an SSE floating point to integer
+/// conversion of a constant floating point. If roundTowardZero is false, the
+/// default IEEE rounding is used (toward nearest, ties to even). This matches
+/// the behavior of the non-truncating SSE instructions in the default rounding
+/// mode. The desired integer type Ty is used to select how many bits are
+/// available for the result. Returns null if the conversion cannot be
+/// performed, otherwise returns the Constant value resulting from the
+/// conversion.
+static Constant *ConstantFoldConvertToInt(ConstantFP *Op, bool roundTowardZero,
+ const Type *Ty) {
+ assert(Op && "Called with NULL operand");
+ APFloat Val(Op->getValueAPF());
+
+ // All of these conversion intrinsics form an integer of at most 64bits.
+ unsigned ResultWidth = cast<IntegerType>(Ty)->getBitWidth();
+ assert(ResultWidth <= 64 &&
+ "Can only constant fold conversions to 64 and 32 bit ints");
+
+ uint64_t UIntVal;
+ bool isExact = false;
+ APFloat::roundingMode mode = roundTowardZero? APFloat::rmTowardZero
+ : APFloat::rmNearestTiesToEven;
+ APFloat::opStatus status = Val.convertToInteger(&UIntVal, ResultWidth,
+ /*isSigned=*/true, mode,
+ &isExact);
+ if (status != APFloat::opOK && status != APFloat::opInexact)
+ return 0;
+ return ConstantInt::get(Ty, UIntVal, /*isSigned=*/true);
+}
+
/// ConstantFoldCall - Attempt to constant fold a call to the specified function
/// with the specified arguments, returning null if unsuccessful.
-
Constant *
llvm::ConstantFoldCall(Function *F,
- Constant* const* Operands, unsigned NumOperands) {
+ Constant *const *Operands, unsigned NumOperands) {
if (!F->hasName()) return 0;
- LLVMContext &Context = F->getContext();
StringRef Name = F->getName();
-
+
const Type *Ty = F->getReturnType();
if (NumOperands == 1) {
if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
- if (Ty!=Type::getFloatTy(F->getContext()) &&
- Ty!=Type::getDoubleTy(Context))
+ if (F->getIntrinsicID() == Intrinsic::convert_to_fp16) {
+ APFloat Val(Op->getValueAPF());
+
+ bool lost = false;
+ Val.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &lost);
+
+ return ConstantInt::get(F->getContext(), Val.bitcastToAPInt());
+ }
+
+ if (!Ty->isFloatTy() && !Ty->isDoubleTy())
+ return 0;
+
+ /// We only fold functions with finite arguments. Folding NaN and inf is
+ /// likely to be aborted with an exception anyway, and some host libms
+ /// have known errors raising exceptions.
+ if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity())
return 0;
+
/// Currently APFloat versions of these functions do not exist, so we use
/// the host native double versions. Float versions are not called
/// directly but for all these it is true (float)(f((double)arg)) ==
/// f(arg). Long double not supported yet.
- double V = Ty==Type::getFloatTy(F->getContext()) ?
- (double)Op->getValueAPF().convertToFloat():
+ double V = Ty->isFloatTy() ? (double)Op->getValueAPF().convertToFloat() :
Op->getValueAPF().convertToDouble();
switch (Name[0]) {
case 'a':
if (Name == "acos")
- return ConstantFoldFP(acos, V, Ty, Context);
+ return ConstantFoldFP(acos, V, Ty);
else if (Name == "asin")
- return ConstantFoldFP(asin, V, Ty, Context);
+ return ConstantFoldFP(asin, V, Ty);
else if (Name == "atan")
- return ConstantFoldFP(atan, V, Ty, Context);
+ return ConstantFoldFP(atan, V, Ty);
break;
case 'c':
if (Name == "ceil")
- return ConstantFoldFP(ceil, V, Ty, Context);
+ return ConstantFoldFP(ceil, V, Ty);
else if (Name == "cos")
- return ConstantFoldFP(cos, V, Ty, Context);
+ return ConstantFoldFP(cos, V, Ty);
else if (Name == "cosh")
- return ConstantFoldFP(cosh, V, Ty, Context);
+ return ConstantFoldFP(cosh, V, Ty);
else if (Name == "cosf")
- return ConstantFoldFP(cos, V, Ty, Context);
+ return ConstantFoldFP(cos, V, Ty);
break;
case 'e':
if (Name == "exp")
- return ConstantFoldFP(exp, V, Ty, Context);
+ return ConstantFoldFP(exp, V, Ty);
+
+ if (Name == "exp2") {
+ // Constant fold exp2(x) as pow(2,x) in case the host doesn't have a
+ // C99 library.
+ return ConstantFoldBinaryFP(pow, 2.0, V, Ty);
+ }
break;
case 'f':
if (Name == "fabs")
- return ConstantFoldFP(fabs, V, Ty, Context);
+ return ConstantFoldFP(fabs, V, Ty);
else if (Name == "floor")
- return ConstantFoldFP(floor, V, Ty, Context);
+ return ConstantFoldFP(floor, V, Ty);
break;
case 'l':
if (Name == "log" && V > 0)
- return ConstantFoldFP(log, V, Ty, Context);
+ return ConstantFoldFP(log, V, Ty);
else if (Name == "log10" && V > 0)
- return ConstantFoldFP(log10, V, Ty, Context);
- else if (Name == "llvm.sqrt.f32" ||
- Name == "llvm.sqrt.f64") {
+ return ConstantFoldFP(log10, V, Ty);
+ else if (F->getIntrinsicID() == Intrinsic::sqrt &&
+ (Ty->isFloatTy() || Ty->isDoubleTy())) {
if (V >= -0.0)
- return ConstantFoldFP(sqrt, V, Ty, Context);
+ return ConstantFoldFP(sqrt, V, Ty);
else // Undefined
return Constant::getNullValue(Ty);
}
break;
case 's':
if (Name == "sin")
- return ConstantFoldFP(sin, V, Ty, Context);
+ return ConstantFoldFP(sin, V, Ty);
else if (Name == "sinh")
- return ConstantFoldFP(sinh, V, Ty, Context);
+ return ConstantFoldFP(sinh, V, Ty);
else if (Name == "sqrt" && V >= 0)
- return ConstantFoldFP(sqrt, V, Ty, Context);
+ return ConstantFoldFP(sqrt, V, Ty);
else if (Name == "sqrtf" && V >= 0)
- return ConstantFoldFP(sqrt, V, Ty, Context);
+ return ConstantFoldFP(sqrt, V, Ty);
else if (Name == "sinf")
- return ConstantFoldFP(sin, V, Ty, Context);
+ return ConstantFoldFP(sin, V, Ty);
break;
case 't':
if (Name == "tan")
- return ConstantFoldFP(tan, V, Ty, Context);
+ return ConstantFoldFP(tan, V, Ty);
else if (Name == "tanh")
- return ConstantFoldFP(tanh, V, Ty, Context);
+ return ConstantFoldFP(tanh, V, Ty);
break;
default:
break;
}
- } else if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
- if (Name.startswith("llvm.bswap"))
- return ConstantInt::get(Context, Op->getValue().byteSwap());
- else if (Name.startswith("llvm.ctpop"))
+ return 0;
+ }
+
+ if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
+ switch (F->getIntrinsicID()) {
+ case Intrinsic::bswap:
+ return ConstantInt::get(F->getContext(), Op->getValue().byteSwap());
+ case Intrinsic::ctpop:
return ConstantInt::get(Ty, Op->getValue().countPopulation());
- else if (Name.startswith("llvm.cttz"))
+ case Intrinsic::cttz:
return ConstantInt::get(Ty, Op->getValue().countTrailingZeros());
- else if (Name.startswith("llvm.ctlz"))
+ case Intrinsic::ctlz:
return ConstantInt::get(Ty, Op->getValue().countLeadingZeros());
+ case Intrinsic::convert_from_fp16: {
+ APFloat Val(Op->getValue());
+
+ bool lost = false;
+ APFloat::opStatus status =
+ Val.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, &lost);
+
+ // Conversion is always precise.
+ (void)status;
+ assert(status == APFloat::opOK && !lost &&
+ "Precision lost during fp16 constfolding");
+
+ return ConstantFP::get(F->getContext(), Val);
+ }
+ default:
+ return 0;
+ }
+ }
+
+ if (ConstantVector *Op = dyn_cast<ConstantVector>(Operands[0])) {
+ switch (F->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::x86_sse_cvtss2si:
+ case Intrinsic::x86_sse_cvtss2si64:
+ case Intrinsic::x86_sse2_cvtsd2si:
+ case Intrinsic::x86_sse2_cvtsd2si64:
+ if (ConstantFP *FPOp = dyn_cast<ConstantFP>(Op->getOperand(0)))
+ return ConstantFoldConvertToInt(FPOp, /*roundTowardZero=*/false, Ty);
+ case Intrinsic::x86_sse_cvttss2si:
+ case Intrinsic::x86_sse_cvttss2si64:
+ case Intrinsic::x86_sse2_cvttsd2si:
+ case Intrinsic::x86_sse2_cvttsd2si64:
+ if (ConstantFP *FPOp = dyn_cast<ConstantFP>(Op->getOperand(0)))
+ return ConstantFoldConvertToInt(FPOp, /*roundTowardZero=*/true, Ty);
+ }
+ }
+
+ if (isa<UndefValue>(Operands[0])) {
+ if (F->getIntrinsicID() == Intrinsic::bswap)
+ return Operands[0];
+ return 0;
}
- } else if (NumOperands == 2) {
+
+ return 0;
+ }
+
+ if (NumOperands == 2) {
if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
- if (Ty!=Type::getFloatTy(F->getContext()) &&
- Ty!=Type::getDoubleTy(Context))
+ if (!Ty->isFloatTy() && !Ty->isDoubleTy())
return 0;
- double Op1V = Ty==Type::getFloatTy(F->getContext()) ?
- (double)Op1->getValueAPF().convertToFloat():
+ double Op1V = Ty->isFloatTy() ?
+ (double)Op1->getValueAPF().convertToFloat() :
Op1->getValueAPF().convertToDouble();
if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
- double Op2V = Ty==Type::getFloatTy(F->getContext()) ?
+ if (Op2->getType() != Op1->getType())
+ return 0;
+
+ double Op2V = Ty->isFloatTy() ?
(double)Op2->getValueAPF().convertToFloat():
Op2->getValueAPF().convertToDouble();
- if (Name == "pow") {
- return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty, Context);
- } else if (Name == "fmod") {
- return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty, Context);
- } else if (Name == "atan2") {
- return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty, Context);
- }
+ if (Name == "pow")
+ return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
+ if (Name == "fmod")
+ return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty);
+ if (Name == "atan2")
+ return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
} else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
- if (Name == "llvm.powi.f32") {
- return ConstantFP::get(Context, APFloat((float)std::pow((float)Op1V,
- (int)Op2C->getZExtValue())));
- } else if (Name == "llvm.powi.f64") {
- return ConstantFP::get(Context, APFloat((double)std::pow((double)Op1V,
+ if (F->getIntrinsicID() == Intrinsic::powi && Ty->isFloatTy())
+ return ConstantFP::get(F->getContext(),
+ APFloat((float)std::pow((float)Op1V,
(int)Op2C->getZExtValue())));
+ if (F->getIntrinsicID() == Intrinsic::powi && Ty->isDoubleTy())
+ return ConstantFP::get(F->getContext(),
+ APFloat((double)std::pow((double)Op1V,
+ (int)Op2C->getZExtValue())));
+ }
+ return 0;
+ }
+
+
+ if (ConstantInt *Op1 = dyn_cast<ConstantInt>(Operands[0])) {
+ if (ConstantInt *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
+ switch (F->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::sadd_with_overflow:
+ case Intrinsic::uadd_with_overflow:
+ case Intrinsic::ssub_with_overflow:
+ case Intrinsic::usub_with_overflow:
+ case Intrinsic::smul_with_overflow:
+ case Intrinsic::umul_with_overflow: {
+ APInt Res;
+ bool Overflow;
+ switch (F->getIntrinsicID()) {
+ default: assert(0 && "Invalid case");
+ case Intrinsic::sadd_with_overflow:
+ Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow);
+ break;
+ case Intrinsic::uadd_with_overflow:
+ Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow);
+ break;
+ case Intrinsic::ssub_with_overflow:
+ Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow);
+ break;
+ case Intrinsic::usub_with_overflow:
+ Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow);
+ break;
+ case Intrinsic::smul_with_overflow:
+ Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow);
+ break;
+ case Intrinsic::umul_with_overflow:
+ Res = Op1->getValue().umul_ov(Op2->getValue(), Overflow);
+ break;
+ }
+ Constant *Ops[] = {
+ ConstantInt::get(F->getContext(), Res),
+ ConstantInt::get(Type::getInt1Ty(F->getContext()), Overflow)
+ };
+ return ConstantStruct::get(F->getContext(), Ops, 2, false);
+ }
}
}
+
+ return 0;
}
+ return 0;
}
return 0;
}
-
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