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6854f86296
Besides APFloat, this involved removing code from two places that thought they knew the result of frem(0., x) but were wrong. llvm-svn: 62645
1682 lines
69 KiB
C++
1682 lines
69 KiB
C++
//===- ConstantFold.cpp - LLVM constant folder ----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements folding of constants for LLVM. This implements the
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// (internal) ConstantFold.h interface, which is used by the
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// ConstantExpr::get* methods to automatically fold constants when possible.
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//
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// The current constant folding implementation is implemented in two pieces: the
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// template-based folder for simple primitive constants like ConstantInt, and
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// the special case hackery that we use to symbolically evaluate expressions
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// that use ConstantExprs.
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//
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//===----------------------------------------------------------------------===//
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#include "ConstantFold.h"
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#include "llvm/Constants.h"
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#include "llvm/Instructions.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/GlobalAlias.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/ManagedStatic.h"
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#include "llvm/Support/MathExtras.h"
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#include <limits>
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// ConstantFold*Instruction Implementations
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//===----------------------------------------------------------------------===//
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/// BitCastConstantVector - Convert the specified ConstantVector node to the
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/// specified vector type. At this point, we know that the elements of the
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/// input vector constant are all simple integer or FP values.
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static Constant *BitCastConstantVector(ConstantVector *CV,
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const VectorType *DstTy) {
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// If this cast changes element count then we can't handle it here:
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// doing so requires endianness information. This should be handled by
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// Analysis/ConstantFolding.cpp
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unsigned NumElts = DstTy->getNumElements();
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if (NumElts != CV->getNumOperands())
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return 0;
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// Check to verify that all elements of the input are simple.
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for (unsigned i = 0; i != NumElts; ++i) {
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if (!isa<ConstantInt>(CV->getOperand(i)) &&
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!isa<ConstantFP>(CV->getOperand(i)))
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return 0;
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}
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// Bitcast each element now.
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std::vector<Constant*> Result;
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const Type *DstEltTy = DstTy->getElementType();
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for (unsigned i = 0; i != NumElts; ++i)
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Result.push_back(ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy));
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return ConstantVector::get(Result);
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}
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/// This function determines which opcode to use to fold two constant cast
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/// expressions together. It uses CastInst::isEliminableCastPair to determine
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/// the opcode. Consequently its just a wrapper around that function.
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/// @brief Determine if it is valid to fold a cast of a cast
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static unsigned
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foldConstantCastPair(
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unsigned opc, ///< opcode of the second cast constant expression
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const ConstantExpr*Op, ///< the first cast constant expression
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const Type *DstTy ///< desintation type of the first cast
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) {
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assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
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assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
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assert(CastInst::isCast(opc) && "Invalid cast opcode");
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// The the types and opcodes for the two Cast constant expressions
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const Type *SrcTy = Op->getOperand(0)->getType();
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const Type *MidTy = Op->getType();
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Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
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Instruction::CastOps secondOp = Instruction::CastOps(opc);
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// Let CastInst::isEliminableCastPair do the heavy lifting.
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return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
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Type::Int64Ty);
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}
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static Constant *FoldBitCast(Constant *V, const Type *DestTy) {
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const Type *SrcTy = V->getType();
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if (SrcTy == DestTy)
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return V; // no-op cast
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// Check to see if we are casting a pointer to an aggregate to a pointer to
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// the first element. If so, return the appropriate GEP instruction.
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if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
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if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy))
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if (PTy->getAddressSpace() == DPTy->getAddressSpace()) {
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SmallVector<Value*, 8> IdxList;
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IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
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const Type *ElTy = PTy->getElementType();
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while (ElTy != DPTy->getElementType()) {
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if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
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if (STy->getNumElements() == 0) break;
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ElTy = STy->getElementType(0);
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IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
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} else if (const SequentialType *STy =
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dyn_cast<SequentialType>(ElTy)) {
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if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
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ElTy = STy->getElementType();
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IdxList.push_back(IdxList[0]);
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} else {
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break;
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}
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}
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if (ElTy == DPTy->getElementType())
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return ConstantExpr::getGetElementPtr(V, &IdxList[0], IdxList.size());
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}
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// Handle casts from one vector constant to another. We know that the src
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// and dest type have the same size (otherwise its an illegal cast).
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if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
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if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
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assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
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"Not cast between same sized vectors!");
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SrcTy = NULL;
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// First, check for null. Undef is already handled.
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if (isa<ConstantAggregateZero>(V))
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return Constant::getNullValue(DestTy);
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if (ConstantVector *CV = dyn_cast<ConstantVector>(V))
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return BitCastConstantVector(CV, DestPTy);
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}
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// Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts
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// This allows for other simplifications (although some of them
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// can only be handled by Analysis/ConstantFolding.cpp).
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if (isa<ConstantInt>(V) || isa<ConstantFP>(V))
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return ConstantExpr::getBitCast(ConstantVector::get(&V, 1), DestPTy);
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}
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// Finally, implement bitcast folding now. The code below doesn't handle
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// bitcast right.
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if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
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return ConstantPointerNull::get(cast<PointerType>(DestTy));
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// Handle integral constant input.
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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if (DestTy->isInteger())
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// Integral -> Integral. This is a no-op because the bit widths must
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// be the same. Consequently, we just fold to V.
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return V;
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if (DestTy->isFloatingPoint()) {
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assert((DestTy == Type::DoubleTy || DestTy == Type::FloatTy) &&
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"Unknown FP type!");
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return ConstantFP::get(APFloat(CI->getValue()));
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}
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// Otherwise, can't fold this (vector?)
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return 0;
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}
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// Handle ConstantFP input.
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if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
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// FP -> Integral.
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if (DestTy == Type::Int32Ty) {
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return ConstantInt::get(FP->getValueAPF().bitcastToAPInt());
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} else {
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assert(DestTy == Type::Int64Ty && "only support f32/f64 for now!");
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return ConstantInt::get(FP->getValueAPF().bitcastToAPInt());
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}
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}
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return 0;
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}
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Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
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const Type *DestTy) {
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if (isa<UndefValue>(V)) {
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// zext(undef) = 0, because the top bits will be zero.
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// sext(undef) = 0, because the top bits will all be the same.
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// [us]itofp(undef) = 0, because the result value is bounded.
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if (opc == Instruction::ZExt || opc == Instruction::SExt ||
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opc == Instruction::UIToFP || opc == Instruction::SIToFP)
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return Constant::getNullValue(DestTy);
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return UndefValue::get(DestTy);
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}
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// No compile-time operations on this type yet.
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if (V->getType() == Type::PPC_FP128Ty || DestTy == Type::PPC_FP128Ty)
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return 0;
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// If the cast operand is a constant expression, there's a few things we can
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// do to try to simplify it.
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if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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if (CE->isCast()) {
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// Try hard to fold cast of cast because they are often eliminable.
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if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
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return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
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} else if (CE->getOpcode() == Instruction::GetElementPtr) {
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// If all of the indexes in the GEP are null values, there is no pointer
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// adjustment going on. We might as well cast the source pointer.
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bool isAllNull = true;
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for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
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if (!CE->getOperand(i)->isNullValue()) {
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isAllNull = false;
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break;
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}
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if (isAllNull)
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// This is casting one pointer type to another, always BitCast
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return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
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}
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}
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// We actually have to do a cast now. Perform the cast according to the
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// opcode specified.
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switch (opc) {
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case Instruction::FPTrunc:
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case Instruction::FPExt:
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if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
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bool ignored;
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APFloat Val = FPC->getValueAPF();
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Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle :
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DestTy == Type::DoubleTy ? APFloat::IEEEdouble :
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DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended :
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DestTy == Type::FP128Ty ? APFloat::IEEEquad :
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APFloat::Bogus,
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APFloat::rmNearestTiesToEven, &ignored);
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return ConstantFP::get(Val);
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}
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return 0; // Can't fold.
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case Instruction::FPToUI:
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case Instruction::FPToSI:
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if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
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const APFloat &V = FPC->getValueAPF();
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bool ignored;
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uint64_t x[2];
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uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
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(void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI,
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APFloat::rmTowardZero, &ignored);
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APInt Val(DestBitWidth, 2, x);
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return ConstantInt::get(Val);
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}
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if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
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std::vector<Constant*> res;
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const VectorType *DestVecTy = cast<VectorType>(DestTy);
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const Type *DstEltTy = DestVecTy->getElementType();
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for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
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res.push_back(ConstantExpr::getCast(opc, CV->getOperand(i), DstEltTy));
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return ConstantVector::get(DestVecTy, res);
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}
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return 0; // Can't fold.
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case Instruction::IntToPtr: //always treated as unsigned
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if (V->isNullValue()) // Is it an integral null value?
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return ConstantPointerNull::get(cast<PointerType>(DestTy));
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return 0; // Other pointer types cannot be casted
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case Instruction::PtrToInt: // always treated as unsigned
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if (V->isNullValue()) // is it a null pointer value?
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return ConstantInt::get(DestTy, 0);
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return 0; // Other pointer types cannot be casted
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case Instruction::UIToFP:
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case Instruction::SIToFP:
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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APInt api = CI->getValue();
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const uint64_t zero[] = {0, 0};
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APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(),
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2, zero));
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(void)apf.convertFromAPInt(api,
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opc==Instruction::SIToFP,
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APFloat::rmNearestTiesToEven);
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return ConstantFP::get(apf);
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}
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if (const ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
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std::vector<Constant*> res;
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const VectorType *DestVecTy = cast<VectorType>(DestTy);
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const Type *DstEltTy = DestVecTy->getElementType();
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for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
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res.push_back(ConstantExpr::getCast(opc, CV->getOperand(i), DstEltTy));
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return ConstantVector::get(DestVecTy, res);
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}
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return 0;
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case Instruction::ZExt:
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
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APInt Result(CI->getValue());
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Result.zext(BitWidth);
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return ConstantInt::get(Result);
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}
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return 0;
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case Instruction::SExt:
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
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APInt Result(CI->getValue());
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Result.sext(BitWidth);
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return ConstantInt::get(Result);
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}
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return 0;
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case Instruction::Trunc:
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if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
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APInt Result(CI->getValue());
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Result.trunc(BitWidth);
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return ConstantInt::get(Result);
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}
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return 0;
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case Instruction::BitCast:
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return FoldBitCast(const_cast<Constant*>(V), DestTy);
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default:
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assert(!"Invalid CE CastInst opcode");
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break;
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}
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assert(0 && "Failed to cast constant expression");
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return 0;
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}
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Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
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const Constant *V1,
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const Constant *V2) {
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if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
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return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
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if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
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if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
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if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
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if (V1 == V2) return const_cast<Constant*>(V1);
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return 0;
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}
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Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
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const Constant *Idx) {
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if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
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return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
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if (Val->isNullValue()) // ee(zero, x) -> zero
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return Constant::getNullValue(
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cast<VectorType>(Val->getType())->getElementType());
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if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
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if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
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return CVal->getOperand(CIdx->getZExtValue());
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} else if (isa<UndefValue>(Idx)) {
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// ee({w,x,y,z}, undef) -> w (an arbitrary value).
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return CVal->getOperand(0);
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}
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}
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return 0;
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}
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Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
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const Constant *Elt,
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const Constant *Idx) {
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const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
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if (!CIdx) return 0;
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APInt idxVal = CIdx->getValue();
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if (isa<UndefValue>(Val)) {
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// Insertion of scalar constant into vector undef
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// Optimize away insertion of undef
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if (isa<UndefValue>(Elt))
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return const_cast<Constant*>(Val);
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// Otherwise break the aggregate undef into multiple undefs and do
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// the insertion
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unsigned numOps =
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cast<VectorType>(Val->getType())->getNumElements();
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std::vector<Constant*> Ops;
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Ops.reserve(numOps);
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for (unsigned i = 0; i < numOps; ++i) {
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const Constant *Op =
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(idxVal == i) ? Elt : UndefValue::get(Elt->getType());
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Ops.push_back(const_cast<Constant*>(Op));
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}
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return ConstantVector::get(Ops);
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}
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if (isa<ConstantAggregateZero>(Val)) {
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// Insertion of scalar constant into vector aggregate zero
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// Optimize away insertion of zero
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if (Elt->isNullValue())
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return const_cast<Constant*>(Val);
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// Otherwise break the aggregate zero into multiple zeros and do
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// the insertion
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unsigned numOps =
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cast<VectorType>(Val->getType())->getNumElements();
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std::vector<Constant*> Ops;
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Ops.reserve(numOps);
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for (unsigned i = 0; i < numOps; ++i) {
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const Constant *Op =
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(idxVal == i) ? Elt : Constant::getNullValue(Elt->getType());
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Ops.push_back(const_cast<Constant*>(Op));
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}
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return ConstantVector::get(Ops);
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}
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if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
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// Insertion of scalar constant into vector constant
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std::vector<Constant*> Ops;
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Ops.reserve(CVal->getNumOperands());
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for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
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const Constant *Op =
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(idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i));
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Ops.push_back(const_cast<Constant*>(Op));
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}
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return ConstantVector::get(Ops);
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}
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return 0;
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}
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/// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef
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/// return the specified element value. Otherwise return null.
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static Constant *GetVectorElement(const Constant *C, unsigned EltNo) {
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if (const ConstantVector *CV = dyn_cast<ConstantVector>(C))
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return CV->getOperand(EltNo);
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const Type *EltTy = cast<VectorType>(C->getType())->getElementType();
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if (isa<ConstantAggregateZero>(C))
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return Constant::getNullValue(EltTy);
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if (isa<UndefValue>(C))
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return UndefValue::get(EltTy);
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return 0;
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}
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Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
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const Constant *V2,
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const Constant *Mask) {
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// Undefined shuffle mask -> undefined value.
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if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType());
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unsigned MaskNumElts = cast<VectorType>(Mask->getType())->getNumElements();
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unsigned SrcNumElts = cast<VectorType>(V1->getType())->getNumElements();
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const Type *EltTy = cast<VectorType>(V1->getType())->getElementType();
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// Loop over the shuffle mask, evaluating each element.
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SmallVector<Constant*, 32> Result;
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for (unsigned i = 0; i != MaskNumElts; ++i) {
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Constant *InElt = GetVectorElement(Mask, i);
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if (InElt == 0) return 0;
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if (isa<UndefValue>(InElt))
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InElt = UndefValue::get(EltTy);
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else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) {
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unsigned Elt = CI->getZExtValue();
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if (Elt >= SrcNumElts*2)
|
|
InElt = UndefValue::get(EltTy);
|
|
else if (Elt >= SrcNumElts)
|
|
InElt = GetVectorElement(V2, Elt - SrcNumElts);
|
|
else
|
|
InElt = GetVectorElement(V1, Elt);
|
|
if (InElt == 0) return 0;
|
|
} else {
|
|
// Unknown value.
|
|
return 0;
|
|
}
|
|
Result.push_back(InElt);
|
|
}
|
|
|
|
return ConstantVector::get(&Result[0], Result.size());
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldExtractValueInstruction(const Constant *Agg,
|
|
const unsigned *Idxs,
|
|
unsigned NumIdx) {
|
|
// Base case: no indices, so return the entire value.
|
|
if (NumIdx == 0)
|
|
return const_cast<Constant *>(Agg);
|
|
|
|
if (isa<UndefValue>(Agg)) // ev(undef, x) -> undef
|
|
return UndefValue::get(ExtractValueInst::getIndexedType(Agg->getType(),
|
|
Idxs,
|
|
Idxs + NumIdx));
|
|
|
|
if (isa<ConstantAggregateZero>(Agg)) // ev(0, x) -> 0
|
|
return
|
|
Constant::getNullValue(ExtractValueInst::getIndexedType(Agg->getType(),
|
|
Idxs,
|
|
Idxs + NumIdx));
|
|
|
|
// Otherwise recurse.
|
|
return ConstantFoldExtractValueInstruction(Agg->getOperand(*Idxs),
|
|
Idxs+1, NumIdx-1);
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldInsertValueInstruction(const Constant *Agg,
|
|
const Constant *Val,
|
|
const unsigned *Idxs,
|
|
unsigned NumIdx) {
|
|
// Base case: no indices, so replace the entire value.
|
|
if (NumIdx == 0)
|
|
return const_cast<Constant *>(Val);
|
|
|
|
if (isa<UndefValue>(Agg)) {
|
|
// Insertion of constant into aggregate undef
|
|
// Optimize away insertion of undef
|
|
if (isa<UndefValue>(Val))
|
|
return const_cast<Constant*>(Agg);
|
|
// Otherwise break the aggregate undef into multiple undefs and do
|
|
// the insertion
|
|
const CompositeType *AggTy = cast<CompositeType>(Agg->getType());
|
|
unsigned numOps;
|
|
if (const ArrayType *AR = dyn_cast<ArrayType>(AggTy))
|
|
numOps = AR->getNumElements();
|
|
else
|
|
numOps = cast<StructType>(AggTy)->getNumElements();
|
|
std::vector<Constant*> Ops(numOps);
|
|
for (unsigned i = 0; i < numOps; ++i) {
|
|
const Type *MemberTy = AggTy->getTypeAtIndex(i);
|
|
const Constant *Op =
|
|
(*Idxs == i) ?
|
|
ConstantFoldInsertValueInstruction(UndefValue::get(MemberTy),
|
|
Val, Idxs+1, NumIdx-1) :
|
|
UndefValue::get(MemberTy);
|
|
Ops[i] = const_cast<Constant*>(Op);
|
|
}
|
|
if (isa<StructType>(AggTy))
|
|
return ConstantStruct::get(Ops);
|
|
else
|
|
return ConstantArray::get(cast<ArrayType>(AggTy), Ops);
|
|
}
|
|
if (isa<ConstantAggregateZero>(Agg)) {
|
|
// Insertion of constant into aggregate zero
|
|
// Optimize away insertion of zero
|
|
if (Val->isNullValue())
|
|
return const_cast<Constant*>(Agg);
|
|
// Otherwise break the aggregate zero into multiple zeros and do
|
|
// the insertion
|
|
const CompositeType *AggTy = cast<CompositeType>(Agg->getType());
|
|
unsigned numOps;
|
|
if (const ArrayType *AR = dyn_cast<ArrayType>(AggTy))
|
|
numOps = AR->getNumElements();
|
|
else
|
|
numOps = cast<StructType>(AggTy)->getNumElements();
|
|
std::vector<Constant*> Ops(numOps);
|
|
for (unsigned i = 0; i < numOps; ++i) {
|
|
const Type *MemberTy = AggTy->getTypeAtIndex(i);
|
|
const Constant *Op =
|
|
(*Idxs == i) ?
|
|
ConstantFoldInsertValueInstruction(Constant::getNullValue(MemberTy),
|
|
Val, Idxs+1, NumIdx-1) :
|
|
Constant::getNullValue(MemberTy);
|
|
Ops[i] = const_cast<Constant*>(Op);
|
|
}
|
|
if (isa<StructType>(AggTy))
|
|
return ConstantStruct::get(Ops);
|
|
else
|
|
return ConstantArray::get(cast<ArrayType>(AggTy), Ops);
|
|
}
|
|
if (isa<ConstantStruct>(Agg) || isa<ConstantArray>(Agg)) {
|
|
// Insertion of constant into aggregate constant
|
|
std::vector<Constant*> Ops(Agg->getNumOperands());
|
|
for (unsigned i = 0; i < Agg->getNumOperands(); ++i) {
|
|
const Constant *Op =
|
|
(*Idxs == i) ?
|
|
ConstantFoldInsertValueInstruction(Agg->getOperand(i),
|
|
Val, Idxs+1, NumIdx-1) :
|
|
Agg->getOperand(i);
|
|
Ops[i] = const_cast<Constant*>(Op);
|
|
}
|
|
Constant *C;
|
|
if (isa<StructType>(Agg->getType()))
|
|
C = ConstantStruct::get(Ops);
|
|
else
|
|
C = ConstantArray::get(cast<ArrayType>(Agg->getType()), Ops);
|
|
return C;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// EvalVectorOp - Given two vector constants and a function pointer, apply the
|
|
/// function pointer to each element pair, producing a new ConstantVector
|
|
/// constant. Either or both of V1 and V2 may be NULL, meaning a
|
|
/// ConstantAggregateZero operand.
|
|
static Constant *EvalVectorOp(const ConstantVector *V1,
|
|
const ConstantVector *V2,
|
|
const VectorType *VTy,
|
|
Constant *(*FP)(Constant*, Constant*)) {
|
|
std::vector<Constant*> Res;
|
|
const Type *EltTy = VTy->getElementType();
|
|
for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
|
|
const Constant *C1 = V1 ? V1->getOperand(i) : Constant::getNullValue(EltTy);
|
|
const Constant *C2 = V2 ? V2->getOperand(i) : Constant::getNullValue(EltTy);
|
|
Res.push_back(FP(const_cast<Constant*>(C1),
|
|
const_cast<Constant*>(C2)));
|
|
}
|
|
return ConstantVector::get(Res);
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
|
|
const Constant *C1,
|
|
const Constant *C2) {
|
|
// No compile-time operations on this type yet.
|
|
if (C1->getType() == Type::PPC_FP128Ty)
|
|
return 0;
|
|
|
|
// Handle UndefValue up front
|
|
if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
|
|
switch (Opcode) {
|
|
case Instruction::Xor:
|
|
if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
|
|
// Handle undef ^ undef -> 0 special case. This is a common
|
|
// idiom (misuse).
|
|
return Constant::getNullValue(C1->getType());
|
|
// Fallthrough
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
return UndefValue::get(C1->getType());
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
return Constant::getNullValue(C1->getType());
|
|
case Instruction::UDiv:
|
|
case Instruction::SDiv:
|
|
case Instruction::FDiv:
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
case Instruction::FRem:
|
|
if (!isa<UndefValue>(C2)) // undef / X -> 0
|
|
return Constant::getNullValue(C1->getType());
|
|
return const_cast<Constant*>(C2); // X / undef -> undef
|
|
case Instruction::Or: // X | undef -> -1
|
|
if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
|
|
return ConstantVector::getAllOnesValue(PTy);
|
|
return ConstantInt::getAllOnesValue(C1->getType());
|
|
case Instruction::LShr:
|
|
if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
|
|
return const_cast<Constant*>(C1); // undef lshr undef -> undef
|
|
return Constant::getNullValue(C1->getType()); // X lshr undef -> 0
|
|
// undef lshr X -> 0
|
|
case Instruction::AShr:
|
|
if (!isa<UndefValue>(C2))
|
|
return const_cast<Constant*>(C1); // undef ashr X --> undef
|
|
else if (isa<UndefValue>(C1))
|
|
return const_cast<Constant*>(C1); // undef ashr undef -> undef
|
|
else
|
|
return const_cast<Constant*>(C1); // X ashr undef --> X
|
|
case Instruction::Shl:
|
|
// undef << X -> 0 or X << undef -> 0
|
|
return Constant::getNullValue(C1->getType());
|
|
}
|
|
}
|
|
|
|
// Handle simplifications of the RHS when a constant int.
|
|
if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
|
|
switch (Opcode) {
|
|
case Instruction::Add:
|
|
if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X + 0 == X
|
|
break;
|
|
case Instruction::Sub:
|
|
if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X - 0 == X
|
|
break;
|
|
case Instruction::Mul:
|
|
if (CI2->equalsInt(0)) return const_cast<Constant*>(C2); // X * 0 == 0
|
|
if (CI2->equalsInt(1))
|
|
return const_cast<Constant*>(C1); // X * 1 == X
|
|
break;
|
|
case Instruction::UDiv:
|
|
case Instruction::SDiv:
|
|
if (CI2->equalsInt(1))
|
|
return const_cast<Constant*>(C1); // X / 1 == X
|
|
if (CI2->equalsInt(0))
|
|
return UndefValue::get(CI2->getType()); // X / 0 == undef
|
|
break;
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
if (CI2->equalsInt(1))
|
|
return Constant::getNullValue(CI2->getType()); // X % 1 == 0
|
|
if (CI2->equalsInt(0))
|
|
return UndefValue::get(CI2->getType()); // X % 0 == undef
|
|
break;
|
|
case Instruction::And:
|
|
if (CI2->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
|
|
if (CI2->isAllOnesValue())
|
|
return const_cast<Constant*>(C1); // X & -1 == X
|
|
|
|
if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
|
|
// (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
|
|
if (CE1->getOpcode() == Instruction::ZExt) {
|
|
unsigned DstWidth = CI2->getType()->getBitWidth();
|
|
unsigned SrcWidth =
|
|
CE1->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth));
|
|
if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits)
|
|
return const_cast<Constant*>(C1);
|
|
}
|
|
|
|
// If and'ing the address of a global with a constant, fold it.
|
|
if (CE1->getOpcode() == Instruction::PtrToInt &&
|
|
isa<GlobalValue>(CE1->getOperand(0))) {
|
|
GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0));
|
|
|
|
// Functions are at least 4-byte aligned.
|
|
unsigned GVAlign = GV->getAlignment();
|
|
if (isa<Function>(GV))
|
|
GVAlign = std::max(GVAlign, 4U);
|
|
|
|
if (GVAlign > 1) {
|
|
unsigned DstWidth = CI2->getType()->getBitWidth();
|
|
unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign));
|
|
APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth));
|
|
|
|
// If checking bits we know are clear, return zero.
|
|
if ((CI2->getValue() & BitsNotSet) == CI2->getValue())
|
|
return Constant::getNullValue(CI2->getType());
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Or:
|
|
if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X | 0 == X
|
|
if (CI2->isAllOnesValue())
|
|
return const_cast<Constant*>(C2); // X | -1 == -1
|
|
break;
|
|
case Instruction::Xor:
|
|
if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X ^ 0 == X
|
|
break;
|
|
case Instruction::AShr:
|
|
// ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
|
|
if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1))
|
|
if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
|
|
return ConstantExpr::getLShr(const_cast<Constant*>(C1),
|
|
const_cast<Constant*>(C2));
|
|
break;
|
|
}
|
|
}
|
|
|
|
// At this point we know neither constant is an UndefValue.
|
|
if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
|
|
if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
|
|
using namespace APIntOps;
|
|
const APInt &C1V = CI1->getValue();
|
|
const APInt &C2V = CI2->getValue();
|
|
switch (Opcode) {
|
|
default:
|
|
break;
|
|
case Instruction::Add:
|
|
return ConstantInt::get(C1V + C2V);
|
|
case Instruction::Sub:
|
|
return ConstantInt::get(C1V - C2V);
|
|
case Instruction::Mul:
|
|
return ConstantInt::get(C1V * C2V);
|
|
case Instruction::UDiv:
|
|
assert(!CI2->isNullValue() && "Div by zero handled above");
|
|
return ConstantInt::get(C1V.udiv(C2V));
|
|
case Instruction::SDiv:
|
|
assert(!CI2->isNullValue() && "Div by zero handled above");
|
|
if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
|
|
return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef
|
|
return ConstantInt::get(C1V.sdiv(C2V));
|
|
case Instruction::URem:
|
|
assert(!CI2->isNullValue() && "Div by zero handled above");
|
|
return ConstantInt::get(C1V.urem(C2V));
|
|
case Instruction::SRem:
|
|
assert(!CI2->isNullValue() && "Div by zero handled above");
|
|
if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
|
|
return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef
|
|
return ConstantInt::get(C1V.srem(C2V));
|
|
case Instruction::And:
|
|
return ConstantInt::get(C1V & C2V);
|
|
case Instruction::Or:
|
|
return ConstantInt::get(C1V | C2V);
|
|
case Instruction::Xor:
|
|
return ConstantInt::get(C1V ^ C2V);
|
|
case Instruction::Shl: {
|
|
uint32_t shiftAmt = C2V.getZExtValue();
|
|
if (shiftAmt < C1V.getBitWidth())
|
|
return ConstantInt::get(C1V.shl(shiftAmt));
|
|
else
|
|
return UndefValue::get(C1->getType()); // too big shift is undef
|
|
}
|
|
case Instruction::LShr: {
|
|
uint32_t shiftAmt = C2V.getZExtValue();
|
|
if (shiftAmt < C1V.getBitWidth())
|
|
return ConstantInt::get(C1V.lshr(shiftAmt));
|
|
else
|
|
return UndefValue::get(C1->getType()); // too big shift is undef
|
|
}
|
|
case Instruction::AShr: {
|
|
uint32_t shiftAmt = C2V.getZExtValue();
|
|
if (shiftAmt < C1V.getBitWidth())
|
|
return ConstantInt::get(C1V.ashr(shiftAmt));
|
|
else
|
|
return UndefValue::get(C1->getType()); // too big shift is undef
|
|
}
|
|
}
|
|
}
|
|
} else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
|
|
if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
|
|
APFloat C1V = CFP1->getValueAPF();
|
|
APFloat C2V = CFP2->getValueAPF();
|
|
APFloat C3V = C1V; // copy for modification
|
|
switch (Opcode) {
|
|
default:
|
|
break;
|
|
case Instruction::Add:
|
|
(void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C3V);
|
|
case Instruction::Sub:
|
|
(void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C3V);
|
|
case Instruction::Mul:
|
|
(void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C3V);
|
|
case Instruction::FDiv:
|
|
(void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C3V);
|
|
case Instruction::FRem:
|
|
(void)C3V.mod(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C3V);
|
|
}
|
|
}
|
|
} else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) {
|
|
const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1);
|
|
const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2);
|
|
if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) &&
|
|
(CP2 != NULL || isa<ConstantAggregateZero>(C2))) {
|
|
switch (Opcode) {
|
|
default:
|
|
break;
|
|
case Instruction::Add:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAdd);
|
|
case Instruction::Sub:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSub);
|
|
case Instruction::Mul:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getMul);
|
|
case Instruction::UDiv:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getUDiv);
|
|
case Instruction::SDiv:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSDiv);
|
|
case Instruction::FDiv:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFDiv);
|
|
case Instruction::URem:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getURem);
|
|
case Instruction::SRem:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSRem);
|
|
case Instruction::FRem:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFRem);
|
|
case Instruction::And:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAnd);
|
|
case Instruction::Or:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getOr);
|
|
case Instruction::Xor:
|
|
return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getXor);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (isa<ConstantExpr>(C1)) {
|
|
// There are many possible foldings we could do here. We should probably
|
|
// at least fold add of a pointer with an integer into the appropriate
|
|
// getelementptr. This will improve alias analysis a bit.
|
|
} else if (isa<ConstantExpr>(C2)) {
|
|
// If C2 is a constant expr and C1 isn't, flop them around and fold the
|
|
// other way if possible.
|
|
switch (Opcode) {
|
|
case Instruction::Add:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
// No change of opcode required.
|
|
return ConstantFoldBinaryInstruction(Opcode, C2, C1);
|
|
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
case Instruction::Sub:
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
case Instruction::FDiv:
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
case Instruction::FRem:
|
|
default: // These instructions cannot be flopped around.
|
|
break;
|
|
}
|
|
}
|
|
|
|
// We don't know how to fold this.
|
|
return 0;
|
|
}
|
|
|
|
/// isZeroSizedType - This type is zero sized if its an array or structure of
|
|
/// zero sized types. The only leaf zero sized type is an empty structure.
|
|
static bool isMaybeZeroSizedType(const Type *Ty) {
|
|
if (isa<OpaqueType>(Ty)) return true; // Can't say.
|
|
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
|
|
// If all of elements have zero size, this does too.
|
|
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
|
|
if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
|
|
return true;
|
|
|
|
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
|
|
return isMaybeZeroSizedType(ATy->getElementType());
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// IdxCompare - Compare the two constants as though they were getelementptr
|
|
/// indices. This allows coersion of the types to be the same thing.
|
|
///
|
|
/// If the two constants are the "same" (after coersion), return 0. If the
|
|
/// first is less than the second, return -1, if the second is less than the
|
|
/// first, return 1. If the constants are not integral, return -2.
|
|
///
|
|
static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
|
|
if (C1 == C2) return 0;
|
|
|
|
// Ok, we found a different index. If they are not ConstantInt, we can't do
|
|
// anything with them.
|
|
if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
|
|
return -2; // don't know!
|
|
|
|
// Ok, we have two differing integer indices. Sign extend them to be the same
|
|
// type. Long is always big enough, so we use it.
|
|
if (C1->getType() != Type::Int64Ty)
|
|
C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
|
|
|
|
if (C2->getType() != Type::Int64Ty)
|
|
C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
|
|
|
|
if (C1 == C2) return 0; // They are equal
|
|
|
|
// If the type being indexed over is really just a zero sized type, there is
|
|
// no pointer difference being made here.
|
|
if (isMaybeZeroSizedType(ElTy))
|
|
return -2; // dunno.
|
|
|
|
// If they are really different, now that they are the same type, then we
|
|
// found a difference!
|
|
if (cast<ConstantInt>(C1)->getSExtValue() <
|
|
cast<ConstantInt>(C2)->getSExtValue())
|
|
return -1;
|
|
else
|
|
return 1;
|
|
}
|
|
|
|
/// evaluateFCmpRelation - This function determines if there is anything we can
|
|
/// decide about the two constants provided. This doesn't need to handle simple
|
|
/// things like ConstantFP comparisons, but should instead handle ConstantExprs.
|
|
/// If we can determine that the two constants have a particular relation to
|
|
/// each other, we should return the corresponding FCmpInst predicate,
|
|
/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
|
|
/// ConstantFoldCompareInstruction.
|
|
///
|
|
/// To simplify this code we canonicalize the relation so that the first
|
|
/// operand is always the most "complex" of the two. We consider ConstantFP
|
|
/// to be the simplest, and ConstantExprs to be the most complex.
|
|
static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
|
|
const Constant *V2) {
|
|
assert(V1->getType() == V2->getType() &&
|
|
"Cannot compare values of different types!");
|
|
|
|
// No compile-time operations on this type yet.
|
|
if (V1->getType() == Type::PPC_FP128Ty)
|
|
return FCmpInst::BAD_FCMP_PREDICATE;
|
|
|
|
// Handle degenerate case quickly
|
|
if (V1 == V2) return FCmpInst::FCMP_OEQ;
|
|
|
|
if (!isa<ConstantExpr>(V1)) {
|
|
if (!isa<ConstantExpr>(V2)) {
|
|
// We distilled thisUse the standard constant folder for a few cases
|
|
ConstantInt *R = 0;
|
|
Constant *C1 = const_cast<Constant*>(V1);
|
|
Constant *C2 = const_cast<Constant*>(V2);
|
|
R = dyn_cast<ConstantInt>(
|
|
ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
|
|
if (R && !R->isZero())
|
|
return FCmpInst::FCMP_OEQ;
|
|
R = dyn_cast<ConstantInt>(
|
|
ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
|
|
if (R && !R->isZero())
|
|
return FCmpInst::FCMP_OLT;
|
|
R = dyn_cast<ConstantInt>(
|
|
ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
|
|
if (R && !R->isZero())
|
|
return FCmpInst::FCMP_OGT;
|
|
|
|
// Nothing more we can do
|
|
return FCmpInst::BAD_FCMP_PREDICATE;
|
|
}
|
|
|
|
// If the first operand is simple and second is ConstantExpr, swap operands.
|
|
FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
|
|
if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
|
|
return FCmpInst::getSwappedPredicate(SwappedRelation);
|
|
} else {
|
|
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
|
|
// constantexpr or a simple constant.
|
|
const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
|
|
switch (CE1->getOpcode()) {
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt:
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
// We might be able to do something with these but we don't right now.
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
// There are MANY other foldings that we could perform here. They will
|
|
// probably be added on demand, as they seem needed.
|
|
return FCmpInst::BAD_FCMP_PREDICATE;
|
|
}
|
|
|
|
/// evaluateICmpRelation - This function determines if there is anything we can
|
|
/// decide about the two constants provided. This doesn't need to handle simple
|
|
/// things like integer comparisons, but should instead handle ConstantExprs
|
|
/// and GlobalValues. If we can determine that the two constants have a
|
|
/// particular relation to each other, we should return the corresponding ICmp
|
|
/// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
|
|
///
|
|
/// To simplify this code we canonicalize the relation so that the first
|
|
/// operand is always the most "complex" of the two. We consider simple
|
|
/// constants (like ConstantInt) to be the simplest, followed by
|
|
/// GlobalValues, followed by ConstantExpr's (the most complex).
|
|
///
|
|
static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
|
|
const Constant *V2,
|
|
bool isSigned) {
|
|
assert(V1->getType() == V2->getType() &&
|
|
"Cannot compare different types of values!");
|
|
if (V1 == V2) return ICmpInst::ICMP_EQ;
|
|
|
|
if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
|
|
if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
|
|
// We distilled this down to a simple case, use the standard constant
|
|
// folder.
|
|
ConstantInt *R = 0;
|
|
Constant *C1 = const_cast<Constant*>(V1);
|
|
Constant *C2 = const_cast<Constant*>(V2);
|
|
ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
|
|
R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
|
|
if (R && !R->isZero())
|
|
return pred;
|
|
pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
|
|
R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
|
|
if (R && !R->isZero())
|
|
return pred;
|
|
pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
|
|
R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
|
|
if (R && !R->isZero())
|
|
return pred;
|
|
|
|
// If we couldn't figure it out, bail.
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
// If the first operand is simple, swap operands.
|
|
ICmpInst::Predicate SwappedRelation =
|
|
evaluateICmpRelation(V2, V1, isSigned);
|
|
if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
|
|
return ICmpInst::getSwappedPredicate(SwappedRelation);
|
|
|
|
} else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
|
|
if (isa<ConstantExpr>(V2)) { // Swap as necessary.
|
|
ICmpInst::Predicate SwappedRelation =
|
|
evaluateICmpRelation(V2, V1, isSigned);
|
|
if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
|
|
return ICmpInst::getSwappedPredicate(SwappedRelation);
|
|
else
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
// Now we know that the RHS is a GlobalValue or simple constant,
|
|
// which (since the types must match) means that it's a ConstantPointerNull.
|
|
if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
|
|
// Don't try to decide equality of aliases.
|
|
if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2))
|
|
if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
|
|
return ICmpInst::ICMP_NE;
|
|
} else {
|
|
assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
|
|
// GlobalVals can never be null. Don't try to evaluate aliases.
|
|
if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1))
|
|
return ICmpInst::ICMP_NE;
|
|
}
|
|
} else {
|
|
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
|
|
// constantexpr, a CPR, or a simple constant.
|
|
const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
|
|
const Constant *CE1Op0 = CE1->getOperand(0);
|
|
|
|
switch (CE1->getOpcode()) {
|
|
case Instruction::Trunc:
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt:
|
|
case Instruction::FPToUI:
|
|
case Instruction::FPToSI:
|
|
break; // We can't evaluate floating point casts or truncations.
|
|
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
case Instruction::BitCast:
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
// If the cast is not actually changing bits, and the second operand is a
|
|
// null pointer, do the comparison with the pre-casted value.
|
|
if (V2->isNullValue() &&
|
|
(isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
|
|
bool sgnd = isSigned;
|
|
if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
|
|
if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
|
|
return evaluateICmpRelation(CE1Op0,
|
|
Constant::getNullValue(CE1Op0->getType()),
|
|
sgnd);
|
|
}
|
|
|
|
// If the dest type is a pointer type, and the RHS is a constantexpr cast
|
|
// from the same type as the src of the LHS, evaluate the inputs. This is
|
|
// important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
|
|
// which happens a lot in compilers with tagged integers.
|
|
if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
|
|
if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
|
|
CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
|
|
CE1->getOperand(0)->getType()->isInteger()) {
|
|
bool sgnd = isSigned;
|
|
if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
|
|
if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
|
|
return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
|
|
sgnd);
|
|
}
|
|
break;
|
|
|
|
case Instruction::GetElementPtr:
|
|
// Ok, since this is a getelementptr, we know that the constant has a
|
|
// pointer type. Check the various cases.
|
|
if (isa<ConstantPointerNull>(V2)) {
|
|
// If we are comparing a GEP to a null pointer, check to see if the base
|
|
// of the GEP equals the null pointer.
|
|
if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
|
|
if (GV->hasExternalWeakLinkage())
|
|
// Weak linkage GVals could be zero or not. We're comparing that
|
|
// to null pointer so its greater-or-equal
|
|
return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
|
|
else
|
|
// If its not weak linkage, the GVal must have a non-zero address
|
|
// so the result is greater-than
|
|
return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
|
|
} else if (isa<ConstantPointerNull>(CE1Op0)) {
|
|
// If we are indexing from a null pointer, check to see if we have any
|
|
// non-zero indices.
|
|
for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
|
|
if (!CE1->getOperand(i)->isNullValue())
|
|
// Offsetting from null, must not be equal.
|
|
return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
|
|
// Only zero indexes from null, must still be zero.
|
|
return ICmpInst::ICMP_EQ;
|
|
}
|
|
// Otherwise, we can't really say if the first operand is null or not.
|
|
} else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
|
|
if (isa<ConstantPointerNull>(CE1Op0)) {
|
|
if (CPR2->hasExternalWeakLinkage())
|
|
// Weak linkage GVals could be zero or not. We're comparing it to
|
|
// a null pointer, so its less-or-equal
|
|
return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
|
|
else
|
|
// If its not weak linkage, the GVal must have a non-zero address
|
|
// so the result is less-than
|
|
return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
|
|
} else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
|
|
if (CPR1 == CPR2) {
|
|
// If this is a getelementptr of the same global, then it must be
|
|
// different. Because the types must match, the getelementptr could
|
|
// only have at most one index, and because we fold getelementptr's
|
|
// with a single zero index, it must be nonzero.
|
|
assert(CE1->getNumOperands() == 2 &&
|
|
!CE1->getOperand(1)->isNullValue() &&
|
|
"Suprising getelementptr!");
|
|
return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
|
|
} else {
|
|
// If they are different globals, we don't know what the value is,
|
|
// but they can't be equal.
|
|
return ICmpInst::ICMP_NE;
|
|
}
|
|
}
|
|
} else {
|
|
const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
|
|
const Constant *CE2Op0 = CE2->getOperand(0);
|
|
|
|
// There are MANY other foldings that we could perform here. They will
|
|
// probably be added on demand, as they seem needed.
|
|
switch (CE2->getOpcode()) {
|
|
default: break;
|
|
case Instruction::GetElementPtr:
|
|
// By far the most common case to handle is when the base pointers are
|
|
// obviously to the same or different globals.
|
|
if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
|
|
if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
|
|
return ICmpInst::ICMP_NE;
|
|
// Ok, we know that both getelementptr instructions are based on the
|
|
// same global. From this, we can precisely determine the relative
|
|
// ordering of the resultant pointers.
|
|
unsigned i = 1;
|
|
|
|
// Compare all of the operands the GEP's have in common.
|
|
gep_type_iterator GTI = gep_type_begin(CE1);
|
|
for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
|
|
++i, ++GTI)
|
|
switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
|
|
GTI.getIndexedType())) {
|
|
case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
|
|
case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
|
|
case -2: return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
// Ok, we ran out of things they have in common. If any leftovers
|
|
// are non-zero then we have a difference, otherwise we are equal.
|
|
for (; i < CE1->getNumOperands(); ++i)
|
|
if (!CE1->getOperand(i)->isNullValue()) {
|
|
if (isa<ConstantInt>(CE1->getOperand(i)))
|
|
return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
|
|
else
|
|
return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
|
|
}
|
|
|
|
for (; i < CE2->getNumOperands(); ++i)
|
|
if (!CE2->getOperand(i)->isNullValue()) {
|
|
if (isa<ConstantInt>(CE2->getOperand(i)))
|
|
return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
|
|
else
|
|
return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
|
|
}
|
|
return ICmpInst::ICMP_EQ;
|
|
}
|
|
}
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
|
|
const Constant *C1,
|
|
const Constant *C2) {
|
|
// Fold FCMP_FALSE/FCMP_TRUE unconditionally.
|
|
if (pred == FCmpInst::FCMP_FALSE) {
|
|
if (const VectorType *VT = dyn_cast<VectorType>(C1->getType()))
|
|
return Constant::getNullValue(VectorType::getInteger(VT));
|
|
else
|
|
return ConstantInt::getFalse();
|
|
}
|
|
|
|
if (pred == FCmpInst::FCMP_TRUE) {
|
|
if (const VectorType *VT = dyn_cast<VectorType>(C1->getType()))
|
|
return Constant::getAllOnesValue(VectorType::getInteger(VT));
|
|
else
|
|
return ConstantInt::getTrue();
|
|
}
|
|
|
|
// Handle some degenerate cases first
|
|
if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
|
|
// vicmp/vfcmp -> [vector] undef
|
|
if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType()))
|
|
return UndefValue::get(VectorType::getInteger(VTy));
|
|
|
|
// icmp/fcmp -> i1 undef
|
|
return UndefValue::get(Type::Int1Ty);
|
|
}
|
|
|
|
// No compile-time operations on this type yet.
|
|
if (C1->getType() == Type::PPC_FP128Ty)
|
|
return 0;
|
|
|
|
// icmp eq/ne(null,GV) -> false/true
|
|
if (C1->isNullValue()) {
|
|
if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
|
|
// Don't try to evaluate aliases. External weak GV can be null.
|
|
if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) {
|
|
if (pred == ICmpInst::ICMP_EQ)
|
|
return ConstantInt::getFalse();
|
|
else if (pred == ICmpInst::ICMP_NE)
|
|
return ConstantInt::getTrue();
|
|
}
|
|
// icmp eq/ne(GV,null) -> false/true
|
|
} else if (C2->isNullValue()) {
|
|
if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
|
|
// Don't try to evaluate aliases. External weak GV can be null.
|
|
if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) {
|
|
if (pred == ICmpInst::ICMP_EQ)
|
|
return ConstantInt::getFalse();
|
|
else if (pred == ICmpInst::ICMP_NE)
|
|
return ConstantInt::getTrue();
|
|
}
|
|
}
|
|
|
|
if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
|
|
APInt V1 = cast<ConstantInt>(C1)->getValue();
|
|
APInt V2 = cast<ConstantInt>(C2)->getValue();
|
|
switch (pred) {
|
|
default: assert(0 && "Invalid ICmp Predicate"); return 0;
|
|
case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
|
|
case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
|
|
case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2));
|
|
case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2));
|
|
case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2));
|
|
case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2));
|
|
case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2));
|
|
case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2));
|
|
case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2));
|
|
case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2));
|
|
}
|
|
} else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
|
|
APFloat C1V = cast<ConstantFP>(C1)->getValueAPF();
|
|
APFloat C2V = cast<ConstantFP>(C2)->getValueAPF();
|
|
APFloat::cmpResult R = C1V.compare(C2V);
|
|
switch (pred) {
|
|
default: assert(0 && "Invalid FCmp Predicate"); return 0;
|
|
case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
|
|
case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
|
|
case FCmpInst::FCMP_UNO:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered);
|
|
case FCmpInst::FCMP_ORD:
|
|
return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered);
|
|
case FCmpInst::FCMP_UEQ:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
|
|
R==APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_OEQ:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_UNE:
|
|
return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_ONE:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
|
|
R==APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_ULT:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
|
|
R==APFloat::cmpLessThan);
|
|
case FCmpInst::FCMP_OLT:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan);
|
|
case FCmpInst::FCMP_UGT:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
|
|
R==APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_OGT:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_ULE:
|
|
return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_OLE:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
|
|
R==APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_UGE:
|
|
return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan);
|
|
case FCmpInst::FCMP_OGE:
|
|
return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan ||
|
|
R==APFloat::cmpEqual);
|
|
}
|
|
} else if (isa<VectorType>(C1->getType())) {
|
|
SmallVector<Constant*, 16> C1Elts, C2Elts;
|
|
C1->getVectorElements(C1Elts);
|
|
C2->getVectorElements(C2Elts);
|
|
|
|
// If we can constant fold the comparison of each element, constant fold
|
|
// the whole vector comparison.
|
|
SmallVector<Constant*, 4> ResElts;
|
|
const Type *InEltTy = C1Elts[0]->getType();
|
|
bool isFP = InEltTy->isFloatingPoint();
|
|
const Type *ResEltTy = InEltTy;
|
|
if (isFP)
|
|
ResEltTy = IntegerType::get(InEltTy->getPrimitiveSizeInBits());
|
|
|
|
for (unsigned i = 0, e = C1Elts.size(); i != e; ++i) {
|
|
// Compare the elements, producing an i1 result or constant expr.
|
|
Constant *C;
|
|
if (isFP)
|
|
C = ConstantExpr::getFCmp(pred, C1Elts[i], C2Elts[i]);
|
|
else
|
|
C = ConstantExpr::getICmp(pred, C1Elts[i], C2Elts[i]);
|
|
|
|
// If it is a bool or undef result, convert to the dest type.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
|
|
if (CI->isZero())
|
|
ResElts.push_back(Constant::getNullValue(ResEltTy));
|
|
else
|
|
ResElts.push_back(Constant::getAllOnesValue(ResEltTy));
|
|
} else if (isa<UndefValue>(C)) {
|
|
ResElts.push_back(UndefValue::get(ResEltTy));
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (ResElts.size() == C1Elts.size())
|
|
return ConstantVector::get(&ResElts[0], ResElts.size());
|
|
}
|
|
|
|
if (C1->getType()->isFloatingPoint()) {
|
|
int Result = -1; // -1 = unknown, 0 = known false, 1 = known true.
|
|
switch (evaluateFCmpRelation(C1, C2)) {
|
|
default: assert(0 && "Unknown relation!");
|
|
case FCmpInst::FCMP_UNO:
|
|
case FCmpInst::FCMP_ORD:
|
|
case FCmpInst::FCMP_UEQ:
|
|
case FCmpInst::FCMP_UNE:
|
|
case FCmpInst::FCMP_ULT:
|
|
case FCmpInst::FCMP_UGT:
|
|
case FCmpInst::FCMP_ULE:
|
|
case FCmpInst::FCMP_UGE:
|
|
case FCmpInst::FCMP_TRUE:
|
|
case FCmpInst::FCMP_FALSE:
|
|
case FCmpInst::BAD_FCMP_PREDICATE:
|
|
break; // Couldn't determine anything about these constants.
|
|
case FCmpInst::FCMP_OEQ: // We know that C1 == C2
|
|
Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
|
|
pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
|
|
pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
|
|
break;
|
|
case FCmpInst::FCMP_OLT: // We know that C1 < C2
|
|
Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
|
|
pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
|
|
pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
|
|
break;
|
|
case FCmpInst::FCMP_OGT: // We know that C1 > C2
|
|
Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
|
|
pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
|
|
pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
|
|
break;
|
|
case FCmpInst::FCMP_OLE: // We know that C1 <= C2
|
|
// We can only partially decide this relation.
|
|
if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
|
|
Result = 0;
|
|
else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
|
|
Result = 1;
|
|
break;
|
|
case FCmpInst::FCMP_OGE: // We known that C1 >= C2
|
|
// We can only partially decide this relation.
|
|
if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
|
|
Result = 0;
|
|
else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
|
|
Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_NE: // We know that C1 != C2
|
|
// We can only partially decide this relation.
|
|
if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
|
|
Result = 0;
|
|
else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
|
|
Result = 1;
|
|
break;
|
|
}
|
|
|
|
// If we evaluated the result, return it now.
|
|
if (Result != -1) {
|
|
if (const VectorType *VT = dyn_cast<VectorType>(C1->getType())) {
|
|
if (Result == 0)
|
|
return Constant::getNullValue(VectorType::getInteger(VT));
|
|
else
|
|
return Constant::getAllOnesValue(VectorType::getInteger(VT));
|
|
}
|
|
return ConstantInt::get(Type::Int1Ty, Result);
|
|
}
|
|
|
|
} else {
|
|
// Evaluate the relation between the two constants, per the predicate.
|
|
int Result = -1; // -1 = unknown, 0 = known false, 1 = known true.
|
|
switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
|
|
default: assert(0 && "Unknown relational!");
|
|
case ICmpInst::BAD_ICMP_PREDICATE:
|
|
break; // Couldn't determine anything about these constants.
|
|
case ICmpInst::ICMP_EQ: // We know the constants are equal!
|
|
// If we know the constants are equal, we can decide the result of this
|
|
// computation precisely.
|
|
Result = (pred == ICmpInst::ICMP_EQ ||
|
|
pred == ICmpInst::ICMP_ULE ||
|
|
pred == ICmpInst::ICMP_SLE ||
|
|
pred == ICmpInst::ICMP_UGE ||
|
|
pred == ICmpInst::ICMP_SGE);
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
// If we know that C1 < C2, we can decide the result of this computation
|
|
// precisely.
|
|
Result = (pred == ICmpInst::ICMP_ULT ||
|
|
pred == ICmpInst::ICMP_NE ||
|
|
pred == ICmpInst::ICMP_ULE);
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
// If we know that C1 < C2, we can decide the result of this computation
|
|
// precisely.
|
|
Result = (pred == ICmpInst::ICMP_SLT ||
|
|
pred == ICmpInst::ICMP_NE ||
|
|
pred == ICmpInst::ICMP_SLE);
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
// If we know that C1 > C2, we can decide the result of this computation
|
|
// precisely.
|
|
Result = (pred == ICmpInst::ICMP_UGT ||
|
|
pred == ICmpInst::ICMP_NE ||
|
|
pred == ICmpInst::ICMP_UGE);
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
// If we know that C1 > C2, we can decide the result of this computation
|
|
// precisely.
|
|
Result = (pred == ICmpInst::ICMP_SGT ||
|
|
pred == ICmpInst::ICMP_NE ||
|
|
pred == ICmpInst::ICMP_SGE);
|
|
break;
|
|
case ICmpInst::ICMP_ULE:
|
|
// If we know that C1 <= C2, we can only partially decide this relation.
|
|
if (pred == ICmpInst::ICMP_UGT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_ULT) Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_SLE:
|
|
// If we know that C1 <= C2, we can only partially decide this relation.
|
|
if (pred == ICmpInst::ICMP_SGT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_SLT) Result = 1;
|
|
break;
|
|
|
|
case ICmpInst::ICMP_UGE:
|
|
// If we know that C1 >= C2, we can only partially decide this relation.
|
|
if (pred == ICmpInst::ICMP_ULT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_UGT) Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_SGE:
|
|
// If we know that C1 >= C2, we can only partially decide this relation.
|
|
if (pred == ICmpInst::ICMP_SLT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_SGT) Result = 1;
|
|
break;
|
|
|
|
case ICmpInst::ICMP_NE:
|
|
// If we know that C1 != C2, we can only partially decide this relation.
|
|
if (pred == ICmpInst::ICMP_EQ) Result = 0;
|
|
if (pred == ICmpInst::ICMP_NE) Result = 1;
|
|
break;
|
|
}
|
|
|
|
// If we evaluated the result, return it now.
|
|
if (Result != -1) {
|
|
if (const VectorType *VT = dyn_cast<VectorType>(C1->getType())) {
|
|
if (Result == 0)
|
|
return Constant::getNullValue(VT);
|
|
else
|
|
return Constant::getAllOnesValue(VT);
|
|
}
|
|
return ConstantInt::get(Type::Int1Ty, Result);
|
|
}
|
|
|
|
if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
|
|
// If C2 is a constant expr and C1 isn't, flop them around and fold the
|
|
// other way if possible.
|
|
switch (pred) {
|
|
case ICmpInst::ICMP_EQ:
|
|
case ICmpInst::ICMP_NE:
|
|
// No change of predicate required.
|
|
return ConstantFoldCompareInstruction(pred, C2, C1);
|
|
|
|
case ICmpInst::ICMP_ULT:
|
|
case ICmpInst::ICMP_SLT:
|
|
case ICmpInst::ICMP_UGT:
|
|
case ICmpInst::ICMP_SGT:
|
|
case ICmpInst::ICMP_ULE:
|
|
case ICmpInst::ICMP_SLE:
|
|
case ICmpInst::ICMP_UGE:
|
|
case ICmpInst::ICMP_SGE:
|
|
// Change the predicate as necessary to swap the operands.
|
|
pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
|
|
return ConstantFoldCompareInstruction(pred, C2, C1);
|
|
|
|
default: // These predicates cannot be flopped around.
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
|
|
Constant* const *Idxs,
|
|
unsigned NumIdx) {
|
|
if (NumIdx == 0 ||
|
|
(NumIdx == 1 && Idxs[0]->isNullValue()))
|
|
return const_cast<Constant*>(C);
|
|
|
|
if (isa<UndefValue>(C)) {
|
|
const PointerType *Ptr = cast<PointerType>(C->getType());
|
|
const Type *Ty = GetElementPtrInst::getIndexedType(Ptr,
|
|
(Value **)Idxs,
|
|
(Value **)Idxs+NumIdx);
|
|
assert(Ty != 0 && "Invalid indices for GEP!");
|
|
return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace()));
|
|
}
|
|
|
|
Constant *Idx0 = Idxs[0];
|
|
if (C->isNullValue()) {
|
|
bool isNull = true;
|
|
for (unsigned i = 0, e = NumIdx; i != e; ++i)
|
|
if (!Idxs[i]->isNullValue()) {
|
|
isNull = false;
|
|
break;
|
|
}
|
|
if (isNull) {
|
|
const PointerType *Ptr = cast<PointerType>(C->getType());
|
|
const Type *Ty = GetElementPtrInst::getIndexedType(Ptr,
|
|
(Value**)Idxs,
|
|
(Value**)Idxs+NumIdx);
|
|
assert(Ty != 0 && "Invalid indices for GEP!");
|
|
return
|
|
ConstantPointerNull::get(PointerType::get(Ty,Ptr->getAddressSpace()));
|
|
}
|
|
}
|
|
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
|
|
// Combine Indices - If the source pointer to this getelementptr instruction
|
|
// is a getelementptr instruction, combine the indices of the two
|
|
// getelementptr instructions into a single instruction.
|
|
//
|
|
if (CE->getOpcode() == Instruction::GetElementPtr) {
|
|
const Type *LastTy = 0;
|
|
for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
|
|
I != E; ++I)
|
|
LastTy = *I;
|
|
|
|
if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
|
|
SmallVector<Value*, 16> NewIndices;
|
|
NewIndices.reserve(NumIdx + CE->getNumOperands());
|
|
for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
|
|
NewIndices.push_back(CE->getOperand(i));
|
|
|
|
// Add the last index of the source with the first index of the new GEP.
|
|
// Make sure to handle the case when they are actually different types.
|
|
Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
|
|
// Otherwise it must be an array.
|
|
if (!Idx0->isNullValue()) {
|
|
const Type *IdxTy = Combined->getType();
|
|
if (IdxTy != Idx0->getType()) {
|
|
Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty);
|
|
Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
|
|
Type::Int64Ty);
|
|
Combined = ConstantExpr::get(Instruction::Add, C1, C2);
|
|
} else {
|
|
Combined =
|
|
ConstantExpr::get(Instruction::Add, Idx0, Combined);
|
|
}
|
|
}
|
|
|
|
NewIndices.push_back(Combined);
|
|
NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
|
|
return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
|
|
NewIndices.size());
|
|
}
|
|
}
|
|
|
|
// Implement folding of:
|
|
// int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
|
|
// long 0, long 0)
|
|
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
|
|
//
|
|
if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) {
|
|
if (const PointerType *SPT =
|
|
dyn_cast<PointerType>(CE->getOperand(0)->getType()))
|
|
if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
|
|
if (const ArrayType *CAT =
|
|
dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
|
|
if (CAT->getElementType() == SAT->getElementType())
|
|
return ConstantExpr::getGetElementPtr(
|
|
(Constant*)CE->getOperand(0), Idxs, NumIdx);
|
|
}
|
|
|
|
// Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
|
|
// Into: inttoptr (i64 0 to i8*)
|
|
// This happens with pointers to member functions in C++.
|
|
if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
|
|
isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
|
|
cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) {
|
|
Constant *Base = CE->getOperand(0);
|
|
Constant *Offset = Idxs[0];
|
|
|
|
// Convert the smaller integer to the larger type.
|
|
if (Offset->getType()->getPrimitiveSizeInBits() <
|
|
Base->getType()->getPrimitiveSizeInBits())
|
|
Offset = ConstantExpr::getSExt(Offset, Base->getType());
|
|
else if (Base->getType()->getPrimitiveSizeInBits() <
|
|
Offset->getType()->getPrimitiveSizeInBits())
|
|
Base = ConstantExpr::getZExt(Base, Base->getType());
|
|
|
|
Base = ConstantExpr::getAdd(Base, Offset);
|
|
return ConstantExpr::getIntToPtr(Base, CE->getType());
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|