//
// 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.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/Analysis/ConstantFolding.h"
#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/LLVMContext.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 <cerrno>
using namespace llvm;
//===----------------------------------------------------------------------===//
-// Constant Folding ...
-//
+// Constant Folding internal helper functions
+//===----------------------------------------------------------------------===//
+
+/// 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.
+static bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
+ int64_t &Offset, const TargetData &TD) {
+ // Trivial case, constant is the global.
+ if ((GV = dyn_cast<GlobalValue>(C))) {
+ Offset = 0;
+ return true;
+ }
+
+ // Otherwise, if this isn't a constant expr, bail out.
+ ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
+ if (!CE) return false;
+
+ // Look through ptr->int and ptr->ptr casts.
+ if (CE->getOpcode() == Instruction::PtrToInt ||
+ CE->getOpcode() == Instruction::BitCast)
+ return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD);
+
+ // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
+ 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())
+ return false;
+
+ // If the base isn't a global+constant, we aren't either.
+ if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD))
+ return false;
+
+ // Otherwise, add any offset that our operands provide.
+ gep_type_iterator GTI = gep_type_begin(CE);
+ 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.
+
+ if (const StructType *ST = dyn_cast<StructType>(*GTI)) {
+ // N = N + Offset
+ Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue());
+ } else {
+ const SequentialType *SQT = cast<SequentialType>(*GTI);
+ Offset += TD.getTypeAllocSize(SQT->getElementType())*CI->getSExtValue();
+ }
+ }
+ return true;
+ }
+
+ return false;
+}
+
+
+/// 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){
+ // SROA
+
+ // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
+ // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute
+ // bits.
+
+
+ // If the constant expr is something like &A[123] - &A[4].f, fold this into a
+ // constant. This happens frequently when iterating over a global array.
+ if (Opc == Instruction::Sub && TD) {
+ GlobalValue *GV1, *GV2;
+ int64_t Offs1, Offs2;
+
+ if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, *TD))
+ if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, *TD) &&
+ GV1 == GV2) {
+ // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
+ return ConstantInt::get(Op0->getType(), Offs1-Offs2);
+ }
+ }
+
+ return 0;
+}
+
+/// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP
+/// constant expression, do so.
+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();
+ 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;
+
+ 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;
+
+ // 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()) :
+ 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.
+ }
+
+ // 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) {
+ if (PHINode *PN = dyn_cast<PHINode>(I)) {
+ if (PN->getNumIncomingValues() == 0)
+ return UndefValue::get(PN->getType());
+
+ 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...
+
+ // If we reach here, all incoming values are the same constant.
+ return Result;
+ }
+
+ // Scan the operand list, checking to see if they are all constants, if so,
+ // hand off to ConstantFoldInstOperands.
+ SmallVector<Constant*, 8> Ops;
+ 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!
+
+ 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);
+}
+
+/// 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);
+ else
+ return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(),
+ Ops.data(), Ops.size(), Context, TD);
+}
+
+/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
+/// specified opcode and operands. If successful, the constant result is
+/// returned, if not, null is returned. Note that this function can fail when
+/// attempting to fold instructions like loads and stores, which have no
+/// constant expression form.
+///
+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))
+ return C;
+
+ return ConstantExpr::get(Opcode, Ops[0], Ops[1]);
+ }
+
+ switch (Opcode) {
+ default: return 0;
+ case Instruction::Call:
+ if (Function *F = dyn_cast<Function>(Ops[0]))
+ if (canConstantFoldCallTo(F))
+ return ConstantFoldCall(F, Ops+1, 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.
+ 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::FPTrunc:
+ case Instruction::FPExt:
+ case Instruction::UIToFP:
+ case Instruction::SIToFP:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
+ case Instruction::BitCast:
+ 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:
+ return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
+ case Instruction::InsertElement:
+ return ConstantExpr::getInsertElement(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))
+ 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.
+Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
+ ConstantExpr *CE,
+ LLVMContext &Context) {
+ if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
+ return 0; // Do not allow stepping over the value!
+
+ // Loop over all of the operands, tracking down which value we are
+ // addressing...
+ gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
+ for (++I; I != E; ++I)
+ if (const StructType *STy = dyn_cast<StructType>(*I)) {
+ ConstantInt *CU = cast<ConstantInt>(I.getOperand());
+ assert(CU->getZExtValue() < STy->getNumElements() &&
+ "Struct index out of range!");
+ unsigned El = (unsigned)CU->getZExtValue();
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
+ C = CS->getOperand(El);
+ } else if (isa<ConstantAggregateZero>(C)) {
+ C = Constant::getNullValue(STy->getElementType(El));
+ } else if (isa<UndefValue>(C)) {
+ C = UndefValue::get(STy->getElementType(El));
+ } else {
+ return 0;
+ }
+ } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(*I)) {
+ if (CI->getZExtValue() >= ATy->getNumElements())
+ return 0;
+ if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
+ C = CA->getOperand(CI->getZExtValue());
+ else if (isa<ConstantAggregateZero>(C))
+ C = Constant::getNullValue(ATy->getElementType());
+ else if (isa<UndefValue>(C))
+ C = UndefValue::get(ATy->getElementType());
+ else
+ return 0;
+ } else if (const VectorType *PTy = dyn_cast<VectorType>(*I)) {
+ if (CI->getZExtValue() >= PTy->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());
+ else if (isa<UndefValue>(C))
+ C = UndefValue::get(PTy->getElementType());
+ else
+ return 0;
+ } else {
+ return 0;
+ }
+ } else {
+ return 0;
+ }
+ return C;
+}
+
+
+//===----------------------------------------------------------------------===//
+// Constant Folding for Calls
+//
/// 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::bswap_i16:
- case Intrinsic::bswap_i32:
- case Intrinsic::bswap_i64:
- // FIXME: these should be constant folded as well
- //case Intrinsic::ctpop_i8:
- //case Intrinsic::ctpop_i16:
- //case Intrinsic::ctpop_i32:
- //case Intrinsic::ctpop_i64:
- //case Intrinsic::ctlz_i8:
- //case Intrinsic::ctlz_i16:
- //case Intrinsic::ctlz_i32:
- //case Intrinsic::ctlz_i64:
- //case Intrinsic::cttz_i8:
- //case Intrinsic::cttz_i16:
- //case Intrinsic::cttz_i32:
- //case Intrinsic::cttz_i64:
+ case Intrinsic::sqrt:
+ case Intrinsic::powi:
+ case Intrinsic::bswap:
+ case Intrinsic::ctpop:
+ case Intrinsic::ctlz:
+ case Intrinsic::cttz:
return true;
default: 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";
}
}
-Constant *
-llvm::ConstantFoldFP(double (*NativeFP)(double), double V, const Type *Ty) {
+static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
+ const Type *Ty, LLVMContext &Context) {
errno = 0;
V = NativeFP(V);
- if (errno == 0)
- return ConstantFP::get(Ty, V);
- return 0;
+ if (errno != 0) {
+ errno = 0;
+ 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));
+ 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;
+ V = NativeFP(V, W);
+ if (errno != 0) {
+ errno = 0;
+ 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));
+ 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, const std::vector<Constant*> &Operands) {
- const std::string &Name = F->getName();
+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 (Operands.size() == 1) {
+ 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;
+ if (Ty!=Type::getFloatTy(F->getContext()) &&
+ Ty!=Type::getDoubleTy(Context))
+ 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():
+ 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;
}
} else if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
- uint64_t V = Op->getZExtValue();
- if (Name == "llvm.bswap.i16")
- return ConstantInt::get(Ty, ByteSwap_16(V));
- else if (Name == "llvm.bswap.i32")
- return ConstantInt::get(Ty, ByteSwap_32(V));
- else if (Name == "llvm.bswap.i64")
- return ConstantInt::get(Ty, ByteSwap_64(V));
+ 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());
}
- } else if (Operands.size() == 2) {
+ } else if (NumOperands == 2) {
if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
- double Op1V = Op1->getValue();
+ if (Ty!=Type::getFloatTy(F->getContext()) &&
+ Ty!=Type::getDoubleTy(Context))
+ return 0;
+ double Op1V = Ty==Type::getFloatTy(F->getContext()) ?
+ (double)Op1->getValueAPF().convertToFloat():
+ Op1->getValueAPF().convertToDouble();
if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
- double Op2V = Op2->getValue();
+ double Op2V = Ty==Type::getFloatTy(F->getContext()) ?
+ (double)Op2->getValueAPF().convertToFloat():
+ Op2->getValueAPF().convertToDouble();
if (Name == "pow") {
- errno = 0;
- double V = pow(Op1V, Op2V);
- if (errno == 0)
- return ConstantFP::get(Ty, V);
+ return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty, Context);
} 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));
+ return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty, Context);
+ } else 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(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,
+ (int)Op2C->getZExtValue())));
+ }
}
}
}