-//===-- ConstantFolding.cpp - Analyze constant folding possibilities ------===//
+//===-- ConstantFolding.cpp - Fold instructions into constants ------------===//
//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
-// 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/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
+#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
-#include "llvm/ADT/SmallVector.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include <cerrno>
if (CE->getOpcode() == Instruction::GetElementPtr) {
// Cannot compute this if the element type of the pointer is missing size
// info.
- if (!cast<PointerType>(CE->getOperand(0)->getType())->getElementType()->isSized())
+ if (!cast<PointerType>(CE->getOperand(0)->getType())
+ ->getElementType()->isSized())
return false;
// If the base isn't a global+constant, we aren't either.
// Otherwise, add any offset that our operands provide.
gep_type_iterator GTI = gep_type_begin(CE);
- for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i, ++GTI) {
- ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(i));
+ for (User::const_op_iterator i = CE->op_begin() + 1, e = CE->op_end();
+ 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.
Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue());
} else {
const SequentialType *SQT = cast<SequentialType>(*GTI);
- Offset += TD.getTypeSize(SQT->getElementType())*CI->getSExtValue();
+ Offset += TD.getTypeAllocSize(SQT->getElementType())*CI->getSExtValue();
}
}
return true;
return false;
}
+/// 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->getOperand(0), Str) && !Str.empty()) {
+ unsigned len = Str.length();
+ const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
+ unsigned numBits = Ty->getPrimitiveSizeInBits();
+ // Replace LI with immediate integer store.
+ if ((numBits >> 3) == len + 1) {
+ APInt StrVal(numBits, 0);
+ APInt SingleChar(numBits, 0);
+ if (TD->isLittleEndian()) {
+ for (signed i = len-1; i >= 0; i--) {
+ SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+ StrVal = (StrVal << 8) | SingleChar;
+ }
+ } else {
+ for (unsigned i = 0; i < len; i++) {
+ SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+ StrVal = (StrVal << 8) | SingleChar;
+ }
+ // Append NULL at the end.
+ SingleChar = 0;
+ StrVal = (StrVal << 8) | SingleChar;
+ }
+ return ConstantInt::get(CE->getContext(), StrVal);
+ }
+ }
+
+ // 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>(CE->getUnderlyingObject())){
+ 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);
+ }
+ }
+
+ 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
+/// 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){
+ Constant *Op1, const TargetData *TD,
+ LLVMContext &Context){
// SROA
// Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
}
}
- // TODO: Fold icmp setne/seteq as well.
return 0;
}
/// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
/// constant expression, do so.
-static Constant *SymbolicallyEvaluateGEP(Constant** Ops, unsigned NumOps,
+static Constant *SymbolicallyEvaluateGEP(Constant* const* Ops, unsigned NumOps,
const Type *ResultTy,
+ LLVMContext &Context,
const TargetData *TD) {
Constant *Ptr = Ops[0];
- if (!cast<PointerType>(Ptr->getType())->getElementType()->isSized())
+ 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();
+ BasePtr.zextOrTrunc(BitWidth);
+ }
+
+ if (BasePtr == 0)
+ BaseIsInt = false;
+ }
+
+ // 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]))
+ return 0;
- if (TD && Ptr->isNullValue()) {
- // 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'
- bool isFoldableGEP = true;
- for (unsigned i = 1; i != NumOps; ++i)
- if (!isa<ConstantInt>(Ops[i])) {
- isFoldableGEP = false;
+ APInt Offset = APInt(BitWidth,
+ TD->getIndexedOffset(Ptr->getType(),
+ (Value**)Ops+1, NumOps-1));
+ // 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);
+ return ConstantExpr::getIntToPtr(C, ResultTy);
+ }
+
+ // Otherwise form a regular getelementptr. Recompute the indices so that
+ // we eliminate over-indexing of the notional static type array bounds.
+ // This makes it easy to determine if the getelementptr is "inbounds".
+ // Also, this helps GlobalOpt do SROA on GlobalVariables.
+ const Type *Ty = Ptr->getType();
+ 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) && !NewIdxs.empty())
break;
+ // Determine which element of the array the offset points into.
+ APInt ElemSize(BitWidth, TD->getTypeAllocSize(ATy->getElementType()));
+ if (ElemSize == 0)
+ return 0;
+ APInt NewIdx = Offset.udiv(ElemSize);
+ Offset -= NewIdx * ElemSize;
+ NewIdxs.push_back(ConstantInt::get(TD->getIntPtrType(Context), NewIdx));
+ Ty = ATy->getElementType();
+ } else if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+ // Determine which field of the struct the offset points into. The
+ // getZExtValue is at least as safe as the StructLayout API because we
+ // 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));
+ Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx));
+ Ty = STy->getTypeAtIndex(ElIdx);
+ } else {
+ // We've reached some non-indexable type.
+ break;
+ }
+ } while (Ty != cast<PointerType>(ResultTy)->getElementType());
+
+ // If we haven't used up the entire offset by descending the static
+ // type, then the offset is pointing into the middle of an indivisible
+ // member, so we can't simplify it.
+ if (Offset != 0)
+ return 0;
+
+ // 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);
+
+ 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.
}
- if (isFoldableGEP) {
- uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
- (Value**)Ops+1, NumOps-1);
- Constant *C = ConstantInt::get(TD->getIntPtrType(), Offset);
- return ConstantExpr::getIntToPtr(C, ResultTy);
+
+ // 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());
}
}
/// 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, const TargetData *TD) {
+Constant *llvm::ConstantFoldInstruction(Instruction *I, LLVMContext &Context,
+ const TargetData *TD) {
if (PHINode *PN = dyn_cast<PHINode>(I)) {
if (PN->getNumIncomingValues() == 0)
- return Constant::getNullValue(PN->getType());
+ return UndefValue::get(PN->getType());
Constant *Result = dyn_cast<Constant>(PN->getIncomingValue(0));
if (Result == 0) return 0;
// Scan the operand list, checking to see if they are all constants, if so,
// hand off to ConstantFoldInstOperands.
SmallVector<Constant*, 8> Ops;
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (Constant *Op = dyn_cast<Constant>(I->getOperand(i)))
+ for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
+ if (Constant *Op = dyn_cast<Constant>(*i))
Ops.push_back(Op);
else
return 0; // All operands not constant!
- return ConstantFoldInstOperands(I, &Ops[0], Ops.size(), TD);
+ if (const CmpInst *CI = dyn_cast<CmpInst>(I))
+ return ConstantFoldCompareInstOperands(CI->getPredicate(),
+ Ops.data(), Ops.size(),
+ Context, TD);
+
+ if (const LoadInst *LI = dyn_cast<LoadInst>(I))
+ return ConstantFoldLoadInst(LI, TD);
+
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ Ops.data(), Ops.size(), Context, 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,
+ 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));
+
+ if (CE->isCompare())
+ return ConstantFoldCompareInstOperands(CE->getPredicate(),
+ Ops.data(), Ops.size(),
+ Context, TD);
+ return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(),
+ Ops.data(), Ops.size(), Context, TD);
}
/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
/// attempting to fold instructions like loads and stores, which have no
/// constant expression form.
///
-Constant *llvm::ConstantFoldInstOperands(const Instruction* I,
- Constant** Ops, unsigned NumOps,
+Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
+ Constant* const* Ops, unsigned NumOps,
+ LLVMContext &Context,
const TargetData *TD) {
- unsigned Opc = I->getOpcode();
- const Type *DestTy = I->getType();
-
// Handle easy binops first.
- if (isa<BinaryOperator>(I)) {
+ if (Instruction::isBinaryOp(Opcode)) {
if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1]))
- if (Constant *C = SymbolicallyEvaluateBinop(I->getOpcode(), Ops[0],
- Ops[1], TD))
+ if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD,
+ Context))
return C;
- return ConstantExpr::get(Opc, Ops[0], Ops[1]);
+ return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
}
- switch (Opc) {
+ switch (Opcode) {
default: return 0;
case Instruction::Call:
if (Function *F = dyn_cast<Function>(Ops[0]))
return 0;
case Instruction::ICmp:
case Instruction::FCmp:
- return ConstantExpr::getCompare(cast<CmpInst>(I)->getPredicate(), Ops[0],
- Ops[1]);
+ 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.
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
+ if (TD && CE->getOpcode() == Instruction::IntToPtr) {
+ Constant *Input = CE->getOperand(0);
+ unsigned InWidth = Input->getType()->getScalarSizeInBits();
+ if (TD->getPointerSizeInBits() < InWidth) {
+ Constant *Mask =
+ ConstantInt::get(Context, APInt::getLowBitsSet(InWidth,
+ TD->getPointerSizeInBits()));
+ Input = ConstantExpr::getAnd(Input, Mask);
+ }
+ // Do a zext or trunc to get to the dest size.
+ return ConstantExpr::getIntegerCast(Input, DestTy, false);
+ }
+ }
+ return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
+ case Instruction::IntToPtr:
+ // 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 (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);
+ }
+ }
+ }
+ }
+ }
+ }
+ return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::SIToFP:
case Instruction::FPToUI:
case Instruction::FPToSI:
- case Instruction::PtrToInt:
- case Instruction::IntToPtr:
+ return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::BitCast:
- return ConstantExpr::getCast(Opc, Ops[0], DestTy);
+ if (TD)
+ if (Constant *C = FoldBitCast(Ops[0], DestTy, *TD, Context))
+ return C;
+ return ConstantExpr::getBitCast(Ops[0], DestTy);
case Instruction::Select:
return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
case Instruction::ExtractElement:
case Instruction::ShuffleVector:
return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
case Instruction::GetElementPtr:
- if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, I->getType(), TD))
+ if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, Context, TD))
return C;
return ConstantExpr::getGetElementPtr(Ops[0], Ops+1, NumOps-1);
}
}
+/// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
+/// instruction (icmp/fcmp) with the specified operands. If it fails, it
+/// returns a constant expression of the specified operands.
+///
+Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
+ Constant*const * Ops,
+ unsigned NumOps,
+ LLVMContext &Context,
+ const TargetData *TD) {
+ // fold: icmp (inttoptr x), null -> icmp x, 0
+ // fold: icmp (ptrtoint x), 0 -> icmp x, null
+ // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y
+ // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
+ //
+ // 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 (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);
+ }
+
+ // 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) {
+ Constant *C = CE0->getOperand(0);
+ Constant *NewOps[] = { C, Constant::getNullValue(C->getType()) };
+ // FIXME!
+ return ConstantFoldCompareInstOperands(Predicate, NewOps, 2,
+ Context, TD);
+ }
+ }
+
+ if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops[1])) {
+ if (TD && CE0->getOpcode() == CE1->getOpcode()) {
+ const Type *IntPtrTy = TD->getIntPtrType(Context);
+
+ if (CE0->getOpcode() == Instruction::IntToPtr) {
+ // Convert the integer value to the right size to ensure we get the
+ // proper extension or truncation.
+ Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0),
+ IntPtrTy, false);
+ Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
+ IntPtrTy, false);
+ Constant *NewOps[] = { C0, C1 };
+ return ConstantFoldCompareInstOperands(Predicate, NewOps, 2,
+ Context, 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);
+ }
+ }
+ }
+ }
+ return ConstantExpr::getCompare(Predicate, Ops[0], Ops[1]);
+}
+
+
/// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
/// getelementptr constantexpr, return the constant value being addressed by the
/// constant expression, or null if something is funny and we can't decide.
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 {
/// canConstantFoldCallTo - Return true if its even possible to fold a call to
/// the specified function.
bool
-llvm::canConstantFoldCallTo(Function *F) {
- const std::string &Name = F->getName();
-
+llvm::canConstantFoldCallTo(const Function *F) {
switch (F->getIntrinsicID()) {
- case Intrinsic::sqrt_f32:
- case Intrinsic::sqrt_f64:
- case Intrinsic::powi_f32:
- case Intrinsic::powi_f64:
+ case Intrinsic::sqrt:
+ case Intrinsic::powi:
case Intrinsic::bswap:
case Intrinsic::ctpop:
case Intrinsic::ctlz:
case Intrinsic::cttz:
+ case Intrinsic::uadd_with_overflow:
+ case Intrinsic::usub_with_overflow:
+ case Intrinsic::sadd_with_overflow:
+ case Intrinsic::ssub_with_overflow:
return true;
- default: break;
+ default:
+ return false;
+ case 0: break;
}
- switch (Name[0])
- {
- case 'a':
- return Name == "acos" || Name == "asin" || Name == "atan" ||
- Name == "atan2";
- case 'c':
- return Name == "ceil" || Name == "cos" || Name == "cosf" ||
- Name == "cosh";
- case 'e':
- return Name == "exp";
- case 'f':
- return Name == "fabs" || Name == "fmod" || Name == "floor";
- case 'l':
- return Name == "log" || Name == "log10";
- case 'p':
- return Name == "pow";
- case 's':
- return Name == "sin" || Name == "sinh" ||
- Name == "sqrt" || Name == "sqrtf";
- case 't':
- return Name == "tan" || Name == "tanh";
- default:
- return false;
+ if (!F->hasName()) return false;
+ StringRef Name = F->getName();
+
+ // In these cases, the check of the length is required. We don't want to
+ // return true for a name like "cos\0blah" which strcmp would return equal to
+ // "cos", but has length 8.
+ switch (Name[0]) {
+ default: return false;
+ case 'a':
+ return Name == "acos" || Name == "asin" ||
+ Name == "atan" || Name == "atan2";
+ case 'c':
+ return Name == "cos" || Name == "ceil" || Name == "cosf" || Name == "cosh";
+ case 'e':
+ return Name == "exp";
+ case 'f':
+ return Name == "fabs" || Name == "fmod" || Name == "floor";
+ case 'l':
+ return Name == "log" || Name == "log10";
+ case 'p':
+ return Name == "pow";
+ case 's':
+ return Name == "sin" || Name == "sinh" || Name == "sqrt" ||
+ Name == "sinf" || Name == "sqrtf";
+ case 't':
+ return Name == "tan" || Name == "tanh";
}
}
static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
- const Type *Ty) {
+ const Type *Ty, LLVMContext &Context) {
errno = 0;
V = NativeFP(V);
- if (errno == 0)
- return ConstantFP::get(Ty, V);
+ if (errno != 0) {
+ errno = 0;
+ return 0;
+ }
+
+ if (Ty->isFloatTy())
+ return ConstantFP::get(Context, APFloat((float)V));
+ if (Ty->isDoubleTy())
+ return ConstantFP::get(Context, 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;
- return 0;
+ V = NativeFP(V, W);
+ if (errno != 0) {
+ errno = 0;
+ return 0;
+ }
+
+ if (Ty->isFloatTy())
+ return ConstantFP::get(Context, APFloat((float)V));
+ if (Ty->isDoubleTy())
+ return ConstantFP::get(Context, APFloat(V));
+ llvm_unreachable("Can only constant fold float/double");
+ return 0; // dummy return to suppress warning
}
/// 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** Operands, unsigned NumOperands) {
- const std::string &Name = F->getName();
- const Type *Ty = F->getReturnType();
+llvm::ConstantFoldCall(Function *F,
+ 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])) {
- double V = Op->getValue();
- switch (Name[0])
- {
- case 'a':
- if (Name == "acos")
- return ConstantFoldFP(acos, V, Ty);
- else if (Name == "asin")
- return ConstantFoldFP(asin, V, Ty);
- else if (Name == "atan")
- return ConstantFP::get(Ty, atan(V));
- break;
- case 'c':
- if (Name == "ceil")
- return ConstantFoldFP(ceil, V, Ty);
- else if (Name == "cos")
- return ConstantFP::get(Ty, cos(V));
- else if (Name == "cosh")
- return ConstantFP::get(Ty, cosh(V));
- break;
- case 'e':
- if (Name == "exp")
- return ConstantFP::get(Ty, exp(V));
- break;
- case 'f':
- if (Name == "fabs")
- return ConstantFP::get(Ty, fabs(V));
- else if (Name == "floor")
- return ConstantFoldFP(floor, V, Ty);
- break;
- case 'l':
- if (Name == "log" && V > 0)
- return ConstantFP::get(Ty, log(V));
- else if (Name == "log10" && V > 0)
- return ConstantFoldFP(log10, V, Ty);
- else if (Name == "llvm.sqrt.f32" || Name == "llvm.sqrt.f64") {
- if (V >= -0.0)
- return ConstantFP::get(Ty, sqrt(V));
- else // Undefined
- return ConstantFP::get(Ty, 0.0);
- }
- break;
- case 's':
- if (Name == "sin")
- return ConstantFP::get(Ty, sin(V));
- else if (Name == "sinh")
- return ConstantFP::get(Ty, sinh(V));
- else if (Name == "sqrt" && V >= 0)
- return ConstantFP::get(Ty, sqrt(V));
- else if (Name == "sqrtf" && V >= 0)
- return ConstantFP::get(Ty, sqrt((float)V));
- break;
- case 't':
- if (Name == "tan")
- return ConstantFP::get(Ty, tan(V));
- else if (Name == "tanh")
- return ConstantFP::get(Ty, tanh(V));
- break;
- default:
- break;
- }
- } else if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
- const IntegerType *OpTy = cast<IntegerType>(Op->getType());
- if (Name.size() > 11 && !memcmp(&Name[0], "llvm.bswap", 10)) {
- return ConstantInt::get(Op->getValue().byteSwap());
- } else if (Name.size() > 11 && !memcmp(&Name[0],"llvm.ctpop",10)) {
- uint64_t ctpop = Op->getValue().countPopulation();
- return ConstantInt::get(OpTy, ctpop);
- } else if (Name.size() > 10 && !memcmp(&Name[0], "llvm.cttz", 9)) {
- uint64_t cttz = Op->getValue().countTrailingZeros();
- return ConstantInt::get(OpTy, cttz);
- } else if (Name.size() > 10 && !memcmp(&Name[0], "llvm.ctlz", 9)) {
- uint64_t ctlz = Op->getValue().countLeadingZeros();
- return ConstantInt::get(OpTy, ctlz);
+ if (!Ty->isFloatTy() && !Ty->isDoubleTy())
+ 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->isFloatTy() ? (double)Op->getValueAPF().convertToFloat() :
+ Op->getValueAPF().convertToDouble();
+ switch (Name[0]) {
+ case 'a':
+ if (Name == "acos")
+ return ConstantFoldFP(acos, V, Ty, Context);
+ else if (Name == "asin")
+ return ConstantFoldFP(asin, V, Ty, Context);
+ else if (Name == "atan")
+ return ConstantFoldFP(atan, V, Ty, Context);
+ break;
+ case 'c':
+ if (Name == "ceil")
+ return ConstantFoldFP(ceil, V, Ty, Context);
+ else if (Name == "cos")
+ return ConstantFoldFP(cos, V, Ty, Context);
+ else if (Name == "cosh")
+ return ConstantFoldFP(cosh, V, Ty, Context);
+ else if (Name == "cosf")
+ return ConstantFoldFP(cos, V, Ty, Context);
+ break;
+ case 'e':
+ if (Name == "exp")
+ return ConstantFoldFP(exp, V, Ty, Context);
+ break;
+ case 'f':
+ if (Name == "fabs")
+ return ConstantFoldFP(fabs, V, Ty, Context);
+ else if (Name == "floor")
+ return ConstantFoldFP(floor, V, Ty, Context);
+ break;
+ case 'l':
+ if (Name == "log" && V > 0)
+ return ConstantFoldFP(log, V, Ty, Context);
+ else if (Name == "log10" && V > 0)
+ return ConstantFoldFP(log10, V, Ty, Context);
+ else if (Name == "llvm.sqrt.f32" ||
+ Name == "llvm.sqrt.f64") {
+ if (V >= -0.0)
+ return ConstantFoldFP(sqrt, V, Ty, Context);
+ else // Undefined
+ return Constant::getNullValue(Ty);
+ }
+ break;
+ case 's':
+ if (Name == "sin")
+ return ConstantFoldFP(sin, V, Ty, Context);
+ else if (Name == "sinh")
+ return ConstantFoldFP(sinh, V, Ty, Context);
+ else if (Name == "sqrt" && V >= 0)
+ return ConstantFoldFP(sqrt, V, Ty, Context);
+ else if (Name == "sqrtf" && V >= 0)
+ return ConstantFoldFP(sqrt, V, Ty, Context);
+ else if (Name == "sinf")
+ return ConstantFoldFP(sin, V, Ty, Context);
+ break;
+ case 't':
+ if (Name == "tan")
+ return ConstantFoldFP(tan, V, Ty, Context);
+ else if (Name == "tanh")
+ return ConstantFoldFP(tanh, V, Ty, Context);
+ break;
+ default:
+ break;
}
+ return 0;
+ }
+
+
+ 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 ConstantInt::get(Ty, Op->getValue().countPopulation());
+ else if (Name.startswith("llvm.cttz"))
+ return ConstantInt::get(Ty, Op->getValue().countTrailingZeros());
+ else if (Name.startswith("llvm.ctlz"))
+ return ConstantInt::get(Ty, Op->getValue().countLeadingZeros());
+ return 0;
}
- } else if (NumOperands == 2) {
+
+ return 0;
+ }
+
+ if (NumOperands == 2) {
if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
- double Op1V = Op1->getValue();
+ if (!Ty->isFloatTy() && !Ty->isDoubleTy())
+ return 0;
+ double Op1V = Ty->isFloatTy() ?
+ (double)Op1->getValueAPF().convertToFloat() :
+ Op1->getValueAPF().convertToDouble();
if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
- double Op2V = Op2->getValue();
-
- if (Name == "pow") {
- errno = 0;
- double V = pow(Op1V, Op2V);
- if (errno == 0)
- return ConstantFP::get(Ty, V);
- } else if (Name == "fmod") {
- errno = 0;
- double V = fmod(Op1V, Op2V);
- if (errno == 0)
- return ConstantFP::get(Ty, V);
- } else if (Name == "atan2") {
- return ConstantFP::get(Ty, atan2(Op1V,Op2V));
- }
+ 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);
+ if (Name == "fmod")
+ return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty, Context);
+ if (Name == "atan2")
+ return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty, Context);
} else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
- if (Name == "llvm.powi.f32") {
- return ConstantFP::get(Ty, std::pow((float)Op1V,
- (int)Op2C->getZExtValue()));
- } else if (Name == "llvm.powi.f64") {
- return ConstantFP::get(Ty, std::pow((double)Op1V,
- (int)Op2C->getZExtValue()));
+ if (Name == "llvm.powi.f32")
+ return ConstantFP::get(Context, APFloat((float)std::pow((float)Op1V,
+ (int)Op2C->getZExtValue())));
+ if (Name == "llvm.powi.f64")
+ return ConstantFP::get(Context, 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::uadd_with_overflow: {
+ Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result.
+ Constant *Ops[] = {
+ Res, ConstantExpr::getICmp(CmpInst::ICMP_ULT, Res, Op1) // overflow.
+ };
+ return ConstantStruct::get(F->getContext(), Ops, 2, false);
+ }
+ case Intrinsic::usub_with_overflow: {
+ Constant *Res = ConstantExpr::getSub(Op1, Op2); // result.
+ Constant *Ops[] = {
+ Res, ConstantExpr::getICmp(CmpInst::ICMP_UGT, Res, Op1) // overflow.
+ };
+ return ConstantStruct::get(F->getContext(), Ops, 2, false);
+ }
+ case Intrinsic::sadd_with_overflow: {
+ Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result.
+ Constant *Overflow = ConstantExpr::getSelect(
+ ConstantExpr::getICmp(CmpInst::ICMP_SGT,
+ ConstantInt::get(Op1->getType(), 0), Op1),
+ ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op2),
+ ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op2)); // overflow.
+
+ Constant *Ops[] = { Res, Overflow };
+ return ConstantStruct::get(F->getContext(), Ops, 2, false);
+ }
+ case Intrinsic::ssub_with_overflow: {
+ Constant *Res = ConstantExpr::getSub(Op1, Op2); // result.
+ Constant *Overflow = ConstantExpr::getSelect(
+ ConstantExpr::getICmp(CmpInst::ICMP_SGT,
+ ConstantInt::get(Op2->getType(), 0), Op2),
+ ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op1),
+ ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op1)); // overflow.
+
+ Constant *Ops[] = { Res, Overflow };
+ return ConstantStruct::get(F->getContext(), Ops, 2, false);
+ }
}
}
+
+ return 0;
}
+ return 0;
}
return 0;
}