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3b0d18824a
This was reverted to mitigate mitigate miscompiles caused by the logical and/or to bitwise and/or fold. Reapply it now that the underlying issue has been fixed by D101191. ----- This patch folds more operations to poison. Alive2 proof: https://alive2.llvm.org/ce/z/mxcb9G (it does not contain tests about div/rem because they fold to poison when raising UB) Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D92270
2673 lines
108 KiB
C++
2673 lines
108 KiB
C++
//===- ConstantFold.cpp - LLVM constant folder ----------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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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// pieces that don't need DataLayout, and the pieces that do. This is to avoid
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// a dependence in IR on Target.
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//
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//===----------------------------------------------------------------------===//
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#include "ConstantFold.h"
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#include "llvm/ADT/APSInt.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/GetElementPtrTypeIterator.h"
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#include "llvm/IR/GlobalAlias.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/ManagedStatic.h"
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#include "llvm/Support/MathExtras.h"
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using namespace llvm;
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using namespace llvm::PatternMatch;
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//===----------------------------------------------------------------------===//
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// ConstantFold*Instruction Implementations
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//===----------------------------------------------------------------------===//
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/// Convert the specified vector Constant node to the specified vector type.
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/// At this point, we know that the elements of the input vector constant are
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/// all simple integer or FP values.
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static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) {
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if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy);
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if (CV->isNullValue()) return Constant::getNullValue(DstTy);
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// Do not iterate on scalable vector. The num of elements is unknown at
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// compile-time.
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if (isa<ScalableVectorType>(DstTy))
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return nullptr;
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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 = cast<FixedVectorType>(DstTy)->getNumElements();
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if (NumElts != cast<FixedVectorType>(CV->getType())->getNumElements())
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return nullptr;
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Type *DstEltTy = DstTy->getElementType();
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// Fast path for splatted constants.
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if (Constant *Splat = CV->getSplatValue()) {
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return ConstantVector::getSplat(DstTy->getElementCount(),
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ConstantExpr::getBitCast(Splat, DstEltTy));
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}
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SmallVector<Constant*, 16> Result;
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Type *Ty = IntegerType::get(CV->getContext(), 32);
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for (unsigned i = 0; i != NumElts; ++i) {
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Constant *C =
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ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i));
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C = ConstantExpr::getBitCast(C, DstEltTy);
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Result.push_back(C);
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}
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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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/// 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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ConstantExpr *Op, ///< the first cast constant expression
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Type *DstTy ///< destination 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 types and opcodes for the two Cast constant expressions
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Type *SrcTy = Op->getOperand(0)->getType();
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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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// Assume that pointers are never more than 64 bits wide, and only use this
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// for the middle type. Otherwise we could end up folding away illegal
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// bitcasts between address spaces with different sizes.
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IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext());
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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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nullptr, FakeIntPtrTy, nullptr);
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}
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static Constant *FoldBitCast(Constant *V, Type *DestTy) {
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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 (PointerType *PTy = dyn_cast<PointerType>(V->getType()))
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if (PointerType *DPTy = dyn_cast<PointerType>(DestTy))
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if (PTy->getAddressSpace() == DPTy->getAddressSpace()
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&& PTy->getElementType()->isSized()) {
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SmallVector<Value*, 8> IdxList;
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Value *Zero =
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Constant::getNullValue(Type::getInt32Ty(DPTy->getContext()));
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IdxList.push_back(Zero);
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Type *ElTy = PTy->getElementType();
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while (ElTy && ElTy != DPTy->getElementType()) {
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ElTy = GetElementPtrInst::getTypeAtIndex(ElTy, (uint64_t)0);
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IdxList.push_back(Zero);
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}
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if (ElTy == DPTy->getElementType())
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// This GEP is inbounds because all indices are zero.
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return ConstantExpr::getInBoundsGetElementPtr(PTy->getElementType(),
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V, IdxList);
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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 (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
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if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
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assert(DestPTy->getPrimitiveSizeInBits() ==
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SrcTy->getPrimitiveSizeInBits() &&
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"Not cast between same sized vectors!");
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SrcTy = nullptr;
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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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// Handle ConstantVector and ConstantAggregateVector.
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return BitCastConstantVector(V, 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), 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 (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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if (DestTy->isIntegerTy())
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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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// See note below regarding the PPC_FP128 restriction.
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if (DestTy->isFloatingPointTy() && !DestTy->isPPC_FP128Ty())
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return ConstantFP::get(DestTy->getContext(),
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APFloat(DestTy->getFltSemantics(),
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CI->getValue()));
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// Otherwise, can't fold this (vector?)
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return nullptr;
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}
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// Handle ConstantFP input: FP -> Integral.
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if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
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// PPC_FP128 is really the sum of two consecutive doubles, where the first
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// double is always stored first in memory, regardless of the target
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// endianness. The memory layout of i128, however, depends on the target
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// endianness, and so we can't fold this without target endianness
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// information. This should instead be handled by
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// Analysis/ConstantFolding.cpp
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if (FP->getType()->isPPC_FP128Ty())
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return nullptr;
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// Make sure dest type is compatible with the folded integer constant.
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if (!DestTy->isIntegerTy())
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return nullptr;
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return ConstantInt::get(FP->getContext(),
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FP->getValueAPF().bitcastToAPInt());
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}
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return nullptr;
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}
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/// V is an integer constant which only has a subset of its bytes used.
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/// The bytes used are indicated by ByteStart (which is the first byte used,
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/// counting from the least significant byte) and ByteSize, which is the number
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/// of bytes used.
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///
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/// This function analyzes the specified constant to see if the specified byte
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/// range can be returned as a simplified constant. If so, the constant is
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/// returned, otherwise null is returned.
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static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart,
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unsigned ByteSize) {
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assert(C->getType()->isIntegerTy() &&
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(cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 &&
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"Non-byte sized integer input");
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unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8;
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assert(ByteSize && "Must be accessing some piece");
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assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input");
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assert(ByteSize != CSize && "Should not extract everything");
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// Constant Integers are simple.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
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APInt V = CI->getValue();
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if (ByteStart)
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V.lshrInPlace(ByteStart*8);
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V = V.trunc(ByteSize*8);
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return ConstantInt::get(CI->getContext(), V);
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}
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// In the input is a constant expr, we might be able to recursively simplify.
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// If not, we definitely can't do anything.
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ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
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if (!CE) return nullptr;
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switch (CE->getOpcode()) {
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default: return nullptr;
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case Instruction::Or: {
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Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize);
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if (!RHS)
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return nullptr;
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// X | -1 -> -1.
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if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS))
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if (RHSC->isMinusOne())
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return RHSC;
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Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize);
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if (!LHS)
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return nullptr;
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return ConstantExpr::getOr(LHS, RHS);
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}
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case Instruction::And: {
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Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize);
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if (!RHS)
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return nullptr;
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// X & 0 -> 0.
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if (RHS->isNullValue())
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return RHS;
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Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize);
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if (!LHS)
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return nullptr;
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return ConstantExpr::getAnd(LHS, RHS);
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}
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case Instruction::LShr: {
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ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1));
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if (!Amt)
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return nullptr;
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APInt ShAmt = Amt->getValue();
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// Cannot analyze non-byte shifts.
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if ((ShAmt & 7) != 0)
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return nullptr;
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ShAmt.lshrInPlace(3);
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// If the extract is known to be all zeros, return zero.
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if (ShAmt.uge(CSize - ByteStart))
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return Constant::getNullValue(
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IntegerType::get(CE->getContext(), ByteSize * 8));
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// If the extract is known to be fully in the input, extract it.
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if (ShAmt.ule(CSize - (ByteStart + ByteSize)))
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return ExtractConstantBytes(CE->getOperand(0),
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ByteStart + ShAmt.getZExtValue(), ByteSize);
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// TODO: Handle the 'partially zero' case.
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return nullptr;
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}
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case Instruction::Shl: {
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ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1));
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if (!Amt)
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return nullptr;
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APInt ShAmt = Amt->getValue();
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// Cannot analyze non-byte shifts.
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if ((ShAmt & 7) != 0)
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return nullptr;
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ShAmt.lshrInPlace(3);
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// If the extract is known to be all zeros, return zero.
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if (ShAmt.uge(ByteStart + ByteSize))
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return Constant::getNullValue(
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IntegerType::get(CE->getContext(), ByteSize * 8));
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// If the extract is known to be fully in the input, extract it.
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if (ShAmt.ule(ByteStart))
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return ExtractConstantBytes(CE->getOperand(0),
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ByteStart - ShAmt.getZExtValue(), ByteSize);
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// TODO: Handle the 'partially zero' case.
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return nullptr;
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}
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case Instruction::ZExt: {
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unsigned SrcBitSize =
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cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth();
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// If extracting something that is completely zero, return 0.
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if (ByteStart*8 >= SrcBitSize)
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return Constant::getNullValue(IntegerType::get(CE->getContext(),
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ByteSize*8));
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// If exactly extracting the input, return it.
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if (ByteStart == 0 && ByteSize*8 == SrcBitSize)
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return CE->getOperand(0);
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// If extracting something completely in the input, if the input is a
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// multiple of 8 bits, recurse.
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if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize)
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return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize);
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// Otherwise, if extracting a subset of the input, which is not multiple of
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// 8 bits, do a shift and trunc to get the bits.
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if ((ByteStart+ByteSize)*8 < SrcBitSize) {
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assert((SrcBitSize&7) && "Shouldn't get byte sized case here");
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Constant *Res = CE->getOperand(0);
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if (ByteStart)
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Res = ConstantExpr::getLShr(Res,
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ConstantInt::get(Res->getType(), ByteStart*8));
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return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(),
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ByteSize*8));
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}
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// TODO: Handle the 'partially zero' case.
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return nullptr;
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}
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}
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}
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/// Wrapper around getFoldedSizeOfImpl() that adds caching.
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static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, bool Folded,
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DenseMap<Type *, Constant *> &Cache);
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/// Return a ConstantExpr with type DestTy for sizeof on Ty, with any known
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/// factors factored out. If Folded is false, return null if no factoring was
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/// possible, to avoid endlessly bouncing an unfoldable expression back into the
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/// top-level folder.
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static Constant *getFoldedSizeOfImpl(Type *Ty, Type *DestTy, bool Folded,
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DenseMap<Type *, Constant *> &Cache) {
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// This is the actual implementation of getFoldedSizeOf(). To get the caching
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// behavior, we need to call getFoldedSizeOf() when we recurse.
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if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
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Constant *N = ConstantInt::get(DestTy, ATy->getNumElements());
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Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true, Cache);
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return ConstantExpr::getNUWMul(E, N);
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}
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if (StructType *STy = dyn_cast<StructType>(Ty))
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if (!STy->isPacked()) {
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unsigned NumElems = STy->getNumElements();
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// An empty struct has size zero.
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if (NumElems == 0)
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return ConstantExpr::getNullValue(DestTy);
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// Check for a struct with all members having the same size.
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Constant *MemberSize =
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getFoldedSizeOf(STy->getElementType(0), DestTy, true, Cache);
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bool AllSame = true;
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for (unsigned i = 1; i != NumElems; ++i)
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if (MemberSize !=
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getFoldedSizeOf(STy->getElementType(i), DestTy, true, Cache)) {
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AllSame = false;
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break;
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}
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if (AllSame) {
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Constant *N = ConstantInt::get(DestTy, NumElems);
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return ConstantExpr::getNUWMul(MemberSize, N);
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}
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}
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// Pointer size doesn't depend on the pointee type, so canonicalize them
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// to an arbitrary pointee.
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if (PointerType *PTy = dyn_cast<PointerType>(Ty))
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if (!PTy->getElementType()->isIntegerTy(1))
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return getFoldedSizeOf(
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PointerType::get(IntegerType::get(PTy->getContext(), 1),
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PTy->getAddressSpace()),
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DestTy, true, Cache);
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// If there's no interesting folding happening, bail so that we don't create
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// a constant that looks like it needs folding but really doesn't.
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if (!Folded)
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return nullptr;
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// Base case: Get a regular sizeof expression.
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Constant *C = ConstantExpr::getSizeOf(Ty);
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C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
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DestTy, false),
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C, DestTy);
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return C;
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}
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static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, bool Folded,
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DenseMap<Type *, Constant *> &Cache) {
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// Check for previously generated folded size constant.
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auto It = Cache.find(Ty);
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if (It != Cache.end())
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return It->second;
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return Cache[Ty] = getFoldedSizeOfImpl(Ty, DestTy, Folded, Cache);
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}
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static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, bool Folded) {
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DenseMap<Type *, Constant *> Cache;
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return getFoldedSizeOf(Ty, DestTy, Folded, Cache);
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}
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/// Return a ConstantExpr with type DestTy for alignof on Ty, with any known
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/// factors factored out. If Folded is false, return null if no factoring was
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/// possible, to avoid endlessly bouncing an unfoldable expression back into the
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/// top-level folder.
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static Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, bool Folded) {
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// The alignment of an array is equal to the alignment of the
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// array element. Note that this is not always true for vectors.
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if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
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Constant *C = ConstantExpr::getAlignOf(ATy->getElementType());
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C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
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DestTy,
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false),
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C, DestTy);
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return C;
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}
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if (StructType *STy = dyn_cast<StructType>(Ty)) {
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// Packed structs always have an alignment of 1.
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if (STy->isPacked())
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return ConstantInt::get(DestTy, 1);
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// Otherwise, struct alignment is the maximum alignment of any member.
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// Without target data, we can't compare much, but we can check to see
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// if all the members have the same alignment.
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unsigned NumElems = STy->getNumElements();
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// An empty struct has minimal alignment.
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if (NumElems == 0)
|
|
return ConstantInt::get(DestTy, 1);
|
|
// Check for a struct with all members having the same alignment.
|
|
Constant *MemberAlign =
|
|
getFoldedAlignOf(STy->getElementType(0), DestTy, true);
|
|
bool AllSame = true;
|
|
for (unsigned i = 1; i != NumElems; ++i)
|
|
if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) {
|
|
AllSame = false;
|
|
break;
|
|
}
|
|
if (AllSame)
|
|
return MemberAlign;
|
|
}
|
|
|
|
// Pointer alignment doesn't depend on the pointee type, so canonicalize them
|
|
// to an arbitrary pointee.
|
|
if (PointerType *PTy = dyn_cast<PointerType>(Ty))
|
|
if (!PTy->getElementType()->isIntegerTy(1))
|
|
return
|
|
getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(),
|
|
1),
|
|
PTy->getAddressSpace()),
|
|
DestTy, true);
|
|
|
|
// If there's no interesting folding happening, bail so that we don't create
|
|
// a constant that looks like it needs folding but really doesn't.
|
|
if (!Folded)
|
|
return nullptr;
|
|
|
|
// Base case: Get a regular alignof expression.
|
|
Constant *C = ConstantExpr::getAlignOf(Ty);
|
|
C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
|
|
DestTy, false),
|
|
C, DestTy);
|
|
return C;
|
|
}
|
|
|
|
/// Return a ConstantExpr with type DestTy for offsetof on Ty and FieldNo, with
|
|
/// any known factors factored out. If Folded is false, return null if no
|
|
/// factoring was possible, to avoid endlessly bouncing an unfoldable expression
|
|
/// back into the top-level folder.
|
|
static Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, Type *DestTy,
|
|
bool Folded) {
|
|
if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
|
|
Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false,
|
|
DestTy, false),
|
|
FieldNo, DestTy);
|
|
Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true);
|
|
return ConstantExpr::getNUWMul(E, N);
|
|
}
|
|
|
|
if (StructType *STy = dyn_cast<StructType>(Ty))
|
|
if (!STy->isPacked()) {
|
|
unsigned NumElems = STy->getNumElements();
|
|
// An empty struct has no members.
|
|
if (NumElems == 0)
|
|
return nullptr;
|
|
// Check for a struct with all members having the same size.
|
|
Constant *MemberSize =
|
|
getFoldedSizeOf(STy->getElementType(0), DestTy, true);
|
|
bool AllSame = true;
|
|
for (unsigned i = 1; i != NumElems; ++i)
|
|
if (MemberSize !=
|
|
getFoldedSizeOf(STy->getElementType(i), DestTy, true)) {
|
|
AllSame = false;
|
|
break;
|
|
}
|
|
if (AllSame) {
|
|
Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo,
|
|
false,
|
|
DestTy,
|
|
false),
|
|
FieldNo, DestTy);
|
|
return ConstantExpr::getNUWMul(MemberSize, N);
|
|
}
|
|
}
|
|
|
|
// If there's no interesting folding happening, bail so that we don't create
|
|
// a constant that looks like it needs folding but really doesn't.
|
|
if (!Folded)
|
|
return nullptr;
|
|
|
|
// Base case: Get a regular offsetof expression.
|
|
Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo);
|
|
C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
|
|
DestTy, false),
|
|
C, DestTy);
|
|
return C;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
|
|
Type *DestTy) {
|
|
if (isa<PoisonValue>(V))
|
|
return PoisonValue::get(DestTy);
|
|
|
|
if (isa<UndefValue>(V)) {
|
|
// zext(undef) = 0, because the top bits will be zero.
|
|
// sext(undef) = 0, because the top bits will all be the same.
|
|
// [us]itofp(undef) = 0, because the result value is bounded.
|
|
if (opc == Instruction::ZExt || opc == Instruction::SExt ||
|
|
opc == Instruction::UIToFP || opc == Instruction::SIToFP)
|
|
return Constant::getNullValue(DestTy);
|
|
return UndefValue::get(DestTy);
|
|
}
|
|
|
|
if (V->isNullValue() && !DestTy->isX86_MMXTy() && !DestTy->isX86_AMXTy() &&
|
|
opc != Instruction::AddrSpaceCast)
|
|
return Constant::getNullValue(DestTy);
|
|
|
|
// If the cast operand is a constant expression, there's a few things we can
|
|
// do to try to simplify it.
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
|
|
if (CE->isCast()) {
|
|
// Try hard to fold cast of cast because they are often eliminable.
|
|
if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
|
|
return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
|
|
} else if (CE->getOpcode() == Instruction::GetElementPtr &&
|
|
// Do not fold addrspacecast (gep 0, .., 0). It might make the
|
|
// addrspacecast uncanonicalized.
|
|
opc != Instruction::AddrSpaceCast &&
|
|
// Do not fold bitcast (gep) with inrange index, as this loses
|
|
// information.
|
|
!cast<GEPOperator>(CE)->getInRangeIndex().hasValue() &&
|
|
// Do not fold if the gep type is a vector, as bitcasting
|
|
// operand 0 of a vector gep will result in a bitcast between
|
|
// different sizes.
|
|
!CE->getType()->isVectorTy()) {
|
|
// If all of the indexes in the GEP are null values, there is no pointer
|
|
// adjustment going on. We might as well cast the source pointer.
|
|
bool isAllNull = true;
|
|
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
|
|
if (!CE->getOperand(i)->isNullValue()) {
|
|
isAllNull = false;
|
|
break;
|
|
}
|
|
if (isAllNull)
|
|
// This is casting one pointer type to another, always BitCast
|
|
return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
|
|
}
|
|
}
|
|
|
|
// If the cast operand is a constant vector, perform the cast by
|
|
// operating on each element. In the cast of bitcasts, the element
|
|
// count may be mismatched; don't attempt to handle that here.
|
|
if ((isa<ConstantVector>(V) || isa<ConstantDataVector>(V)) &&
|
|
DestTy->isVectorTy() &&
|
|
cast<FixedVectorType>(DestTy)->getNumElements() ==
|
|
cast<FixedVectorType>(V->getType())->getNumElements()) {
|
|
VectorType *DestVecTy = cast<VectorType>(DestTy);
|
|
Type *DstEltTy = DestVecTy->getElementType();
|
|
// Fast path for splatted constants.
|
|
if (Constant *Splat = V->getSplatValue()) {
|
|
return ConstantVector::getSplat(
|
|
cast<VectorType>(DestTy)->getElementCount(),
|
|
ConstantExpr::getCast(opc, Splat, DstEltTy));
|
|
}
|
|
SmallVector<Constant *, 16> res;
|
|
Type *Ty = IntegerType::get(V->getContext(), 32);
|
|
for (unsigned i = 0,
|
|
e = cast<FixedVectorType>(V->getType())->getNumElements();
|
|
i != e; ++i) {
|
|
Constant *C =
|
|
ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i));
|
|
res.push_back(ConstantExpr::getCast(opc, C, DstEltTy));
|
|
}
|
|
return ConstantVector::get(res);
|
|
}
|
|
|
|
// We actually have to do a cast now. Perform the cast according to the
|
|
// opcode specified.
|
|
switch (opc) {
|
|
default:
|
|
llvm_unreachable("Failed to cast constant expression");
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt:
|
|
if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
|
|
bool ignored;
|
|
APFloat Val = FPC->getValueAPF();
|
|
Val.convert(DestTy->isHalfTy() ? APFloat::IEEEhalf() :
|
|
DestTy->isFloatTy() ? APFloat::IEEEsingle() :
|
|
DestTy->isDoubleTy() ? APFloat::IEEEdouble() :
|
|
DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended() :
|
|
DestTy->isFP128Ty() ? APFloat::IEEEquad() :
|
|
DestTy->isPPC_FP128Ty() ? APFloat::PPCDoubleDouble() :
|
|
APFloat::Bogus(),
|
|
APFloat::rmNearestTiesToEven, &ignored);
|
|
return ConstantFP::get(V->getContext(), Val);
|
|
}
|
|
return nullptr; // Can't fold.
|
|
case Instruction::FPToUI:
|
|
case Instruction::FPToSI:
|
|
if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
|
|
const APFloat &V = FPC->getValueAPF();
|
|
bool ignored;
|
|
uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
|
|
APSInt IntVal(DestBitWidth, opc == Instruction::FPToUI);
|
|
if (APFloat::opInvalidOp ==
|
|
V.convertToInteger(IntVal, APFloat::rmTowardZero, &ignored)) {
|
|
// Undefined behavior invoked - the destination type can't represent
|
|
// the input constant.
|
|
return PoisonValue::get(DestTy);
|
|
}
|
|
return ConstantInt::get(FPC->getContext(), IntVal);
|
|
}
|
|
return nullptr; // Can't fold.
|
|
case Instruction::IntToPtr: //always treated as unsigned
|
|
if (V->isNullValue()) // Is it an integral null value?
|
|
return ConstantPointerNull::get(cast<PointerType>(DestTy));
|
|
return nullptr; // Other pointer types cannot be casted
|
|
case Instruction::PtrToInt: // always treated as unsigned
|
|
// Is it a null pointer value?
|
|
if (V->isNullValue())
|
|
return ConstantInt::get(DestTy, 0);
|
|
// If this is a sizeof-like expression, pull out multiplications by
|
|
// known factors to expose them to subsequent folding. If it's an
|
|
// alignof-like expression, factor out known factors.
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
|
|
if (CE->getOpcode() == Instruction::GetElementPtr &&
|
|
CE->getOperand(0)->isNullValue()) {
|
|
// FIXME: Looks like getFoldedSizeOf(), getFoldedOffsetOf() and
|
|
// getFoldedAlignOf() don't handle the case when DestTy is a vector of
|
|
// pointers yet. We end up in asserts in CastInst::getCastOpcode (see
|
|
// test/Analysis/ConstantFolding/cast-vector.ll). I've only seen this
|
|
// happen in one "real" C-code test case, so it does not seem to be an
|
|
// important optimization to handle vectors here. For now, simply bail
|
|
// out.
|
|
if (DestTy->isVectorTy())
|
|
return nullptr;
|
|
GEPOperator *GEPO = cast<GEPOperator>(CE);
|
|
Type *Ty = GEPO->getSourceElementType();
|
|
if (CE->getNumOperands() == 2) {
|
|
// Handle a sizeof-like expression.
|
|
Constant *Idx = CE->getOperand(1);
|
|
bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne();
|
|
if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) {
|
|
Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true,
|
|
DestTy, false),
|
|
Idx, DestTy);
|
|
return ConstantExpr::getMul(C, Idx);
|
|
}
|
|
} else if (CE->getNumOperands() == 3 &&
|
|
CE->getOperand(1)->isNullValue()) {
|
|
// Handle an alignof-like expression.
|
|
if (StructType *STy = dyn_cast<StructType>(Ty))
|
|
if (!STy->isPacked()) {
|
|
ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2));
|
|
if (CI->isOne() &&
|
|
STy->getNumElements() == 2 &&
|
|
STy->getElementType(0)->isIntegerTy(1)) {
|
|
return getFoldedAlignOf(STy->getElementType(1), DestTy, false);
|
|
}
|
|
}
|
|
// Handle an offsetof-like expression.
|
|
if (Ty->isStructTy() || Ty->isArrayTy()) {
|
|
if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2),
|
|
DestTy, false))
|
|
return C;
|
|
}
|
|
}
|
|
}
|
|
// Other pointer types cannot be casted
|
|
return nullptr;
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
|
|
const APInt &api = CI->getValue();
|
|
APFloat apf(DestTy->getFltSemantics(),
|
|
APInt::getNullValue(DestTy->getPrimitiveSizeInBits()));
|
|
apf.convertFromAPInt(api, opc==Instruction::SIToFP,
|
|
APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(V->getContext(), apf);
|
|
}
|
|
return nullptr;
|
|
case Instruction::ZExt:
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
|
|
uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
|
|
return ConstantInt::get(V->getContext(),
|
|
CI->getValue().zext(BitWidth));
|
|
}
|
|
return nullptr;
|
|
case Instruction::SExt:
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
|
|
uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
|
|
return ConstantInt::get(V->getContext(),
|
|
CI->getValue().sext(BitWidth));
|
|
}
|
|
return nullptr;
|
|
case Instruction::Trunc: {
|
|
if (V->getType()->isVectorTy())
|
|
return nullptr;
|
|
|
|
uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
|
|
return ConstantInt::get(V->getContext(),
|
|
CI->getValue().trunc(DestBitWidth));
|
|
}
|
|
|
|
// The input must be a constantexpr. See if we can simplify this based on
|
|
// the bytes we are demanding. Only do this if the source and dest are an
|
|
// even multiple of a byte.
|
|
if ((DestBitWidth & 7) == 0 &&
|
|
(cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0)
|
|
if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8))
|
|
return Res;
|
|
|
|
return nullptr;
|
|
}
|
|
case Instruction::BitCast:
|
|
return FoldBitCast(V, DestTy);
|
|
case Instruction::AddrSpaceCast:
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldSelectInstruction(Constant *Cond,
|
|
Constant *V1, Constant *V2) {
|
|
// Check for i1 and vector true/false conditions.
|
|
if (Cond->isNullValue()) return V2;
|
|
if (Cond->isAllOnesValue()) return V1;
|
|
|
|
// If the condition is a vector constant, fold the result elementwise.
|
|
if (ConstantVector *CondV = dyn_cast<ConstantVector>(Cond)) {
|
|
auto *V1VTy = CondV->getType();
|
|
SmallVector<Constant*, 16> Result;
|
|
Type *Ty = IntegerType::get(CondV->getContext(), 32);
|
|
for (unsigned i = 0, e = V1VTy->getNumElements(); i != e; ++i) {
|
|
Constant *V;
|
|
Constant *V1Element = ConstantExpr::getExtractElement(V1,
|
|
ConstantInt::get(Ty, i));
|
|
Constant *V2Element = ConstantExpr::getExtractElement(V2,
|
|
ConstantInt::get(Ty, i));
|
|
auto *Cond = cast<Constant>(CondV->getOperand(i));
|
|
if (isa<PoisonValue>(Cond)) {
|
|
V = PoisonValue::get(V1Element->getType());
|
|
} else if (V1Element == V2Element) {
|
|
V = V1Element;
|
|
} else if (isa<UndefValue>(Cond)) {
|
|
V = isa<UndefValue>(V1Element) ? V1Element : V2Element;
|
|
} else {
|
|
if (!isa<ConstantInt>(Cond)) break;
|
|
V = Cond->isNullValue() ? V2Element : V1Element;
|
|
}
|
|
Result.push_back(V);
|
|
}
|
|
|
|
// If we were able to build the vector, return it.
|
|
if (Result.size() == V1VTy->getNumElements())
|
|
return ConstantVector::get(Result);
|
|
}
|
|
|
|
if (isa<PoisonValue>(Cond))
|
|
return PoisonValue::get(V1->getType());
|
|
|
|
if (isa<UndefValue>(Cond)) {
|
|
if (isa<UndefValue>(V1)) return V1;
|
|
return V2;
|
|
}
|
|
|
|
if (V1 == V2) return V1;
|
|
|
|
if (isa<PoisonValue>(V1))
|
|
return V2;
|
|
if (isa<PoisonValue>(V2))
|
|
return V1;
|
|
|
|
// If the true or false value is undef, we can fold to the other value as
|
|
// long as the other value isn't poison.
|
|
auto NotPoison = [](Constant *C) {
|
|
if (isa<PoisonValue>(C))
|
|
return false;
|
|
|
|
// TODO: We can analyze ConstExpr by opcode to determine if there is any
|
|
// possibility of poison.
|
|
if (isa<ConstantExpr>(C))
|
|
return false;
|
|
|
|
if (isa<ConstantInt>(C) || isa<GlobalVariable>(C) || isa<ConstantFP>(C) ||
|
|
isa<ConstantPointerNull>(C) || isa<Function>(C))
|
|
return true;
|
|
|
|
if (C->getType()->isVectorTy())
|
|
return !C->containsPoisonElement() && !C->containsConstantExpression();
|
|
|
|
// TODO: Recursively analyze aggregates or other constants.
|
|
return false;
|
|
};
|
|
if (isa<UndefValue>(V1) && NotPoison(V2)) return V2;
|
|
if (isa<UndefValue>(V2) && NotPoison(V1)) return V1;
|
|
|
|
if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) {
|
|
if (TrueVal->getOpcode() == Instruction::Select)
|
|
if (TrueVal->getOperand(0) == Cond)
|
|
return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2);
|
|
}
|
|
if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) {
|
|
if (FalseVal->getOpcode() == Instruction::Select)
|
|
if (FalseVal->getOperand(0) == Cond)
|
|
return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2));
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val,
|
|
Constant *Idx) {
|
|
auto *ValVTy = cast<VectorType>(Val->getType());
|
|
|
|
// extractelt poison, C -> poison
|
|
// extractelt C, undef -> poison
|
|
if (isa<PoisonValue>(Val) || isa<UndefValue>(Idx))
|
|
return PoisonValue::get(ValVTy->getElementType());
|
|
|
|
// extractelt undef, C -> undef
|
|
if (isa<UndefValue>(Val))
|
|
return UndefValue::get(ValVTy->getElementType());
|
|
|
|
auto *CIdx = dyn_cast<ConstantInt>(Idx);
|
|
if (!CIdx)
|
|
return nullptr;
|
|
|
|
if (auto *ValFVTy = dyn_cast<FixedVectorType>(Val->getType())) {
|
|
// ee({w,x,y,z}, wrong_value) -> poison
|
|
if (CIdx->uge(ValFVTy->getNumElements()))
|
|
return PoisonValue::get(ValFVTy->getElementType());
|
|
}
|
|
|
|
// ee (gep (ptr, idx0, ...), idx) -> gep (ee (ptr, idx), ee (idx0, idx), ...)
|
|
if (auto *CE = dyn_cast<ConstantExpr>(Val)) {
|
|
if (CE->getOpcode() == Instruction::GetElementPtr) {
|
|
SmallVector<Constant *, 8> Ops;
|
|
Ops.reserve(CE->getNumOperands());
|
|
for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
|
|
Constant *Op = CE->getOperand(i);
|
|
if (Op->getType()->isVectorTy()) {
|
|
Constant *ScalarOp = ConstantExpr::getExtractElement(Op, Idx);
|
|
if (!ScalarOp)
|
|
return nullptr;
|
|
Ops.push_back(ScalarOp);
|
|
} else
|
|
Ops.push_back(Op);
|
|
}
|
|
return CE->getWithOperands(Ops, ValVTy->getElementType(), false,
|
|
Ops[0]->getType()->getPointerElementType());
|
|
} else if (CE->getOpcode() == Instruction::InsertElement) {
|
|
if (const auto *IEIdx = dyn_cast<ConstantInt>(CE->getOperand(2))) {
|
|
if (APSInt::isSameValue(APSInt(IEIdx->getValue()),
|
|
APSInt(CIdx->getValue()))) {
|
|
return CE->getOperand(1);
|
|
} else {
|
|
return ConstantExpr::getExtractElement(CE->getOperand(0), CIdx);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// CAZ of type ScalableVectorType and n < CAZ->getMinNumElements() =>
|
|
// extractelt CAZ, n -> 0
|
|
if (auto *ValSVTy = dyn_cast<ScalableVectorType>(Val->getType())) {
|
|
if (!CIdx->uge(ValSVTy->getMinNumElements())) {
|
|
if (auto *CAZ = dyn_cast<ConstantAggregateZero>(Val))
|
|
return CAZ->getElementValue(CIdx->getZExtValue());
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
return Val->getAggregateElement(CIdx);
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldInsertElementInstruction(Constant *Val,
|
|
Constant *Elt,
|
|
Constant *Idx) {
|
|
if (isa<UndefValue>(Idx))
|
|
return PoisonValue::get(Val->getType());
|
|
|
|
ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
|
|
if (!CIdx) return nullptr;
|
|
|
|
// Do not iterate on scalable vector. The num of elements is unknown at
|
|
// compile-time.
|
|
if (isa<ScalableVectorType>(Val->getType()))
|
|
return nullptr;
|
|
|
|
auto *ValTy = cast<FixedVectorType>(Val->getType());
|
|
|
|
unsigned NumElts = ValTy->getNumElements();
|
|
if (CIdx->uge(NumElts))
|
|
return PoisonValue::get(Val->getType());
|
|
|
|
SmallVector<Constant*, 16> Result;
|
|
Result.reserve(NumElts);
|
|
auto *Ty = Type::getInt32Ty(Val->getContext());
|
|
uint64_t IdxVal = CIdx->getZExtValue();
|
|
for (unsigned i = 0; i != NumElts; ++i) {
|
|
if (i == IdxVal) {
|
|
Result.push_back(Elt);
|
|
continue;
|
|
}
|
|
|
|
Constant *C = ConstantExpr::getExtractElement(Val, ConstantInt::get(Ty, i));
|
|
Result.push_back(C);
|
|
}
|
|
|
|
return ConstantVector::get(Result);
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, Constant *V2,
|
|
ArrayRef<int> Mask) {
|
|
auto *V1VTy = cast<VectorType>(V1->getType());
|
|
unsigned MaskNumElts = Mask.size();
|
|
auto MaskEltCount =
|
|
ElementCount::get(MaskNumElts, isa<ScalableVectorType>(V1VTy));
|
|
Type *EltTy = V1VTy->getElementType();
|
|
|
|
// Undefined shuffle mask -> undefined value.
|
|
if (all_of(Mask, [](int Elt) { return Elt == UndefMaskElem; })) {
|
|
return UndefValue::get(FixedVectorType::get(EltTy, MaskNumElts));
|
|
}
|
|
|
|
// If the mask is all zeros this is a splat, no need to go through all
|
|
// elements.
|
|
if (all_of(Mask, [](int Elt) { return Elt == 0; }) &&
|
|
!MaskEltCount.isScalable()) {
|
|
Type *Ty = IntegerType::get(V1->getContext(), 32);
|
|
Constant *Elt =
|
|
ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, 0));
|
|
return ConstantVector::getSplat(MaskEltCount, Elt);
|
|
}
|
|
// Do not iterate on scalable vector. The num of elements is unknown at
|
|
// compile-time.
|
|
if (isa<ScalableVectorType>(V1VTy))
|
|
return nullptr;
|
|
|
|
unsigned SrcNumElts = V1VTy->getElementCount().getKnownMinValue();
|
|
|
|
// Loop over the shuffle mask, evaluating each element.
|
|
SmallVector<Constant*, 32> Result;
|
|
for (unsigned i = 0; i != MaskNumElts; ++i) {
|
|
int Elt = Mask[i];
|
|
if (Elt == -1) {
|
|
Result.push_back(UndefValue::get(EltTy));
|
|
continue;
|
|
}
|
|
Constant *InElt;
|
|
if (unsigned(Elt) >= SrcNumElts*2)
|
|
InElt = UndefValue::get(EltTy);
|
|
else if (unsigned(Elt) >= SrcNumElts) {
|
|
Type *Ty = IntegerType::get(V2->getContext(), 32);
|
|
InElt =
|
|
ConstantExpr::getExtractElement(V2,
|
|
ConstantInt::get(Ty, Elt - SrcNumElts));
|
|
} else {
|
|
Type *Ty = IntegerType::get(V1->getContext(), 32);
|
|
InElt = ConstantExpr::getExtractElement(V1, ConstantInt::get(Ty, Elt));
|
|
}
|
|
Result.push_back(InElt);
|
|
}
|
|
|
|
return ConstantVector::get(Result);
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg,
|
|
ArrayRef<unsigned> Idxs) {
|
|
// Base case: no indices, so return the entire value.
|
|
if (Idxs.empty())
|
|
return Agg;
|
|
|
|
if (Constant *C = Agg->getAggregateElement(Idxs[0]))
|
|
return ConstantFoldExtractValueInstruction(C, Idxs.slice(1));
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg,
|
|
Constant *Val,
|
|
ArrayRef<unsigned> Idxs) {
|
|
// Base case: no indices, so replace the entire value.
|
|
if (Idxs.empty())
|
|
return Val;
|
|
|
|
unsigned NumElts;
|
|
if (StructType *ST = dyn_cast<StructType>(Agg->getType()))
|
|
NumElts = ST->getNumElements();
|
|
else
|
|
NumElts = cast<ArrayType>(Agg->getType())->getNumElements();
|
|
|
|
SmallVector<Constant*, 32> Result;
|
|
for (unsigned i = 0; i != NumElts; ++i) {
|
|
Constant *C = Agg->getAggregateElement(i);
|
|
if (!C) return nullptr;
|
|
|
|
if (Idxs[0] == i)
|
|
C = ConstantFoldInsertValueInstruction(C, Val, Idxs.slice(1));
|
|
|
|
Result.push_back(C);
|
|
}
|
|
|
|
if (StructType *ST = dyn_cast<StructType>(Agg->getType()))
|
|
return ConstantStruct::get(ST, Result);
|
|
return ConstantArray::get(cast<ArrayType>(Agg->getType()), Result);
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldUnaryInstruction(unsigned Opcode, Constant *C) {
|
|
assert(Instruction::isUnaryOp(Opcode) && "Non-unary instruction detected");
|
|
|
|
// Handle scalar UndefValue and scalable vector UndefValue. Fixed-length
|
|
// vectors are always evaluated per element.
|
|
bool IsScalableVector = isa<ScalableVectorType>(C->getType());
|
|
bool HasScalarUndefOrScalableVectorUndef =
|
|
(!C->getType()->isVectorTy() || IsScalableVector) && isa<UndefValue>(C);
|
|
|
|
if (HasScalarUndefOrScalableVectorUndef) {
|
|
switch (static_cast<Instruction::UnaryOps>(Opcode)) {
|
|
case Instruction::FNeg:
|
|
return C; // -undef -> undef
|
|
case Instruction::UnaryOpsEnd:
|
|
llvm_unreachable("Invalid UnaryOp");
|
|
}
|
|
}
|
|
|
|
// Constant should not be UndefValue, unless these are vector constants.
|
|
assert(!HasScalarUndefOrScalableVectorUndef && "Unexpected UndefValue");
|
|
// We only have FP UnaryOps right now.
|
|
assert(!isa<ConstantInt>(C) && "Unexpected Integer UnaryOp");
|
|
|
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
|
|
const APFloat &CV = CFP->getValueAPF();
|
|
switch (Opcode) {
|
|
default:
|
|
break;
|
|
case Instruction::FNeg:
|
|
return ConstantFP::get(C->getContext(), neg(CV));
|
|
}
|
|
} else if (auto *VTy = dyn_cast<FixedVectorType>(C->getType())) {
|
|
|
|
Type *Ty = IntegerType::get(VTy->getContext(), 32);
|
|
// Fast path for splatted constants.
|
|
if (Constant *Splat = C->getSplatValue()) {
|
|
Constant *Elt = ConstantExpr::get(Opcode, Splat);
|
|
return ConstantVector::getSplat(VTy->getElementCount(), Elt);
|
|
}
|
|
|
|
// Fold each element and create a vector constant from those constants.
|
|
SmallVector<Constant *, 16> Result;
|
|
for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
|
|
Constant *ExtractIdx = ConstantInt::get(Ty, i);
|
|
Constant *Elt = ConstantExpr::getExtractElement(C, ExtractIdx);
|
|
|
|
Result.push_back(ConstantExpr::get(Opcode, Elt));
|
|
}
|
|
|
|
return ConstantVector::get(Result);
|
|
}
|
|
|
|
// We don't know how to fold this.
|
|
return nullptr;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1,
|
|
Constant *C2) {
|
|
assert(Instruction::isBinaryOp(Opcode) && "Non-binary instruction detected");
|
|
|
|
// Simplify BinOps with their identity values first. They are no-ops and we
|
|
// can always return the other value, including undef or poison values.
|
|
// FIXME: remove unnecessary duplicated identity patterns below.
|
|
// FIXME: Use AllowRHSConstant with getBinOpIdentity to handle additional ops,
|
|
// like X << 0 = X.
|
|
Constant *Identity = ConstantExpr::getBinOpIdentity(Opcode, C1->getType());
|
|
if (Identity) {
|
|
if (C1 == Identity)
|
|
return C2;
|
|
if (C2 == Identity)
|
|
return C1;
|
|
}
|
|
|
|
// Binary operations propagate poison.
|
|
// FIXME: Currently, or/and i1 poison aren't folded into poison because
|
|
// it causes miscompilation when combined with another optimization in
|
|
// InstCombine (select i1 -> and/or). The select fold is wrong, but
|
|
// fixing it requires an effort, so temporarily disable this until it is
|
|
// fixed.
|
|
bool PoisonFold = !C1->getType()->isIntegerTy(1) ||
|
|
(Opcode != Instruction::Or && Opcode != Instruction::And);
|
|
if (PoisonFold && (isa<PoisonValue>(C1) || isa<PoisonValue>(C2)))
|
|
return PoisonValue::get(C1->getType());
|
|
|
|
// Handle scalar UndefValue and scalable vector UndefValue. Fixed-length
|
|
// vectors are always evaluated per element.
|
|
bool IsScalableVector = isa<ScalableVectorType>(C1->getType());
|
|
bool HasScalarUndefOrScalableVectorUndef =
|
|
(!C1->getType()->isVectorTy() || IsScalableVector) &&
|
|
(isa<UndefValue>(C1) || isa<UndefValue>(C2));
|
|
if (HasScalarUndefOrScalableVectorUndef) {
|
|
switch (static_cast<Instruction::BinaryOps>(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());
|
|
LLVM_FALLTHROUGH;
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
return UndefValue::get(C1->getType());
|
|
case Instruction::And:
|
|
if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef
|
|
return C1;
|
|
return Constant::getNullValue(C1->getType()); // undef & X -> 0
|
|
case Instruction::Mul: {
|
|
// undef * undef -> undef
|
|
if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
|
|
return C1;
|
|
const APInt *CV;
|
|
// X * undef -> undef if X is odd
|
|
if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV)))
|
|
if ((*CV)[0])
|
|
return UndefValue::get(C1->getType());
|
|
|
|
// X * undef -> 0 otherwise
|
|
return Constant::getNullValue(C1->getType());
|
|
}
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
// X / undef -> poison
|
|
// X / 0 -> poison
|
|
if (match(C2, m_CombineOr(m_Undef(), m_Zero())))
|
|
return PoisonValue::get(C2->getType());
|
|
// undef / 1 -> undef
|
|
if (match(C2, m_One()))
|
|
return C1;
|
|
// undef / X -> 0 otherwise
|
|
return Constant::getNullValue(C1->getType());
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
// X % undef -> poison
|
|
// X % 0 -> poison
|
|
if (match(C2, m_CombineOr(m_Undef(), m_Zero())))
|
|
return PoisonValue::get(C2->getType());
|
|
// undef % X -> 0 otherwise
|
|
return Constant::getNullValue(C1->getType());
|
|
case Instruction::Or: // X | undef -> -1
|
|
if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef
|
|
return C1;
|
|
return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0
|
|
case Instruction::LShr:
|
|
// X >>l undef -> poison
|
|
if (isa<UndefValue>(C2))
|
|
return PoisonValue::get(C2->getType());
|
|
// undef >>l 0 -> undef
|
|
if (match(C2, m_Zero()))
|
|
return C1;
|
|
// undef >>l X -> 0
|
|
return Constant::getNullValue(C1->getType());
|
|
case Instruction::AShr:
|
|
// X >>a undef -> poison
|
|
if (isa<UndefValue>(C2))
|
|
return PoisonValue::get(C2->getType());
|
|
// undef >>a 0 -> undef
|
|
if (match(C2, m_Zero()))
|
|
return C1;
|
|
// TODO: undef >>a X -> poison if the shift is exact
|
|
// undef >>a X -> 0
|
|
return Constant::getNullValue(C1->getType());
|
|
case Instruction::Shl:
|
|
// X << undef -> undef
|
|
if (isa<UndefValue>(C2))
|
|
return PoisonValue::get(C2->getType());
|
|
// undef << 0 -> undef
|
|
if (match(C2, m_Zero()))
|
|
return C1;
|
|
// undef << X -> 0
|
|
return Constant::getNullValue(C1->getType());
|
|
case Instruction::FSub:
|
|
// -0.0 - undef --> undef (consistent with "fneg undef")
|
|
if (match(C1, m_NegZeroFP()) && isa<UndefValue>(C2))
|
|
return C2;
|
|
LLVM_FALLTHROUGH;
|
|
case Instruction::FAdd:
|
|
case Instruction::FMul:
|
|
case Instruction::FDiv:
|
|
case Instruction::FRem:
|
|
// [any flop] undef, undef -> undef
|
|
if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
|
|
return C1;
|
|
// [any flop] C, undef -> NaN
|
|
// [any flop] undef, C -> NaN
|
|
// We could potentially specialize NaN/Inf constants vs. 'normal'
|
|
// constants (possibly differently depending on opcode and operand). This
|
|
// would allow returning undef sometimes. But it is always safe to fold to
|
|
// NaN because we can choose the undef operand as NaN, and any FP opcode
|
|
// with a NaN operand will propagate NaN.
|
|
return ConstantFP::getNaN(C1->getType());
|
|
case Instruction::BinaryOpsEnd:
|
|
llvm_unreachable("Invalid BinaryOp");
|
|
}
|
|
}
|
|
|
|
// Neither constant should be UndefValue, unless these are vector constants.
|
|
assert((!HasScalarUndefOrScalableVectorUndef) && "Unexpected UndefValue");
|
|
|
|
// Handle simplifications when the RHS is a constant int.
|
|
if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
|
|
switch (Opcode) {
|
|
case Instruction::Add:
|
|
if (CI2->isZero()) return C1; // X + 0 == X
|
|
break;
|
|
case Instruction::Sub:
|
|
if (CI2->isZero()) return C1; // X - 0 == X
|
|
break;
|
|
case Instruction::Mul:
|
|
if (CI2->isZero()) return C2; // X * 0 == 0
|
|
if (CI2->isOne())
|
|
return C1; // X * 1 == X
|
|
break;
|
|
case Instruction::UDiv:
|
|
case Instruction::SDiv:
|
|
if (CI2->isOne())
|
|
return C1; // X / 1 == X
|
|
if (CI2->isZero())
|
|
return PoisonValue::get(CI2->getType()); // X / 0 == poison
|
|
break;
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
if (CI2->isOne())
|
|
return Constant::getNullValue(CI2->getType()); // X % 1 == 0
|
|
if (CI2->isZero())
|
|
return PoisonValue::get(CI2->getType()); // X % 0 == poison
|
|
break;
|
|
case Instruction::And:
|
|
if (CI2->isZero()) return C2; // X & 0 == 0
|
|
if (CI2->isMinusOne())
|
|
return C1; // X & -1 == X
|
|
|
|
if (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 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));
|
|
|
|
MaybeAlign GVAlign;
|
|
|
|
if (Module *TheModule = GV->getParent()) {
|
|
const DataLayout &DL = TheModule->getDataLayout();
|
|
GVAlign = GV->getPointerAlignment(DL);
|
|
|
|
// If the function alignment is not specified then assume that it
|
|
// is 4.
|
|
// This is dangerous; on x86, the alignment of the pointer
|
|
// corresponds to the alignment of the function, but might be less
|
|
// than 4 if it isn't explicitly specified.
|
|
// However, a fix for this behaviour was reverted because it
|
|
// increased code size (see https://reviews.llvm.org/D55115)
|
|
// FIXME: This code should be deleted once existing targets have
|
|
// appropriate defaults
|
|
if (isa<Function>(GV) && !DL.getFunctionPtrAlign())
|
|
GVAlign = Align(4);
|
|
} else if (isa<Function>(GV)) {
|
|
// Without a datalayout we have to assume the worst case: that the
|
|
// function pointer isn't aligned at all.
|
|
GVAlign = llvm::None;
|
|
} else if (isa<GlobalVariable>(GV)) {
|
|
GVAlign = cast<GlobalVariable>(GV)->getAlign();
|
|
}
|
|
|
|
if (GVAlign && *GVAlign > 1) {
|
|
unsigned DstWidth = CI2->getType()->getBitWidth();
|
|
unsigned SrcWidth = std::min(DstWidth, Log2(*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->isZero()) return C1; // X | 0 == X
|
|
if (CI2->isMinusOne())
|
|
return C2; // X | -1 == -1
|
|
break;
|
|
case Instruction::Xor:
|
|
if (CI2->isZero()) return C1; // X ^ 0 == X
|
|
|
|
if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
|
|
switch (CE1->getOpcode()) {
|
|
default: break;
|
|
case Instruction::ICmp:
|
|
case Instruction::FCmp:
|
|
// cmp pred ^ true -> cmp !pred
|
|
assert(CI2->isOne());
|
|
CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate();
|
|
pred = CmpInst::getInversePredicate(pred);
|
|
return ConstantExpr::getCompare(pred, CE1->getOperand(0),
|
|
CE1->getOperand(1));
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::AShr:
|
|
// ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
|
|
if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1))
|
|
if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
|
|
return ConstantExpr::getLShr(C1, C2);
|
|
break;
|
|
}
|
|
} else if (isa<ConstantInt>(C1)) {
|
|
// If C1 is a ConstantInt and C2 is not, swap the operands.
|
|
if (Instruction::isCommutative(Opcode))
|
|
return ConstantExpr::get(Opcode, C2, C1);
|
|
}
|
|
|
|
if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
|
|
if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
|
|
const APInt &C1V = CI1->getValue();
|
|
const APInt &C2V = CI2->getValue();
|
|
switch (Opcode) {
|
|
default:
|
|
break;
|
|
case Instruction::Add:
|
|
return ConstantInt::get(CI1->getContext(), C1V + C2V);
|
|
case Instruction::Sub:
|
|
return ConstantInt::get(CI1->getContext(), C1V - C2V);
|
|
case Instruction::Mul:
|
|
return ConstantInt::get(CI1->getContext(), C1V * C2V);
|
|
case Instruction::UDiv:
|
|
assert(!CI2->isZero() && "Div by zero handled above");
|
|
return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V));
|
|
case Instruction::SDiv:
|
|
assert(!CI2->isZero() && "Div by zero handled above");
|
|
if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
|
|
return PoisonValue::get(CI1->getType()); // MIN_INT / -1 -> poison
|
|
return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V));
|
|
case Instruction::URem:
|
|
assert(!CI2->isZero() && "Div by zero handled above");
|
|
return ConstantInt::get(CI1->getContext(), C1V.urem(C2V));
|
|
case Instruction::SRem:
|
|
assert(!CI2->isZero() && "Div by zero handled above");
|
|
if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
|
|
return PoisonValue::get(CI1->getType()); // MIN_INT % -1 -> poison
|
|
return ConstantInt::get(CI1->getContext(), C1V.srem(C2V));
|
|
case Instruction::And:
|
|
return ConstantInt::get(CI1->getContext(), C1V & C2V);
|
|
case Instruction::Or:
|
|
return ConstantInt::get(CI1->getContext(), C1V | C2V);
|
|
case Instruction::Xor:
|
|
return ConstantInt::get(CI1->getContext(), C1V ^ C2V);
|
|
case Instruction::Shl:
|
|
if (C2V.ult(C1V.getBitWidth()))
|
|
return ConstantInt::get(CI1->getContext(), C1V.shl(C2V));
|
|
return PoisonValue::get(C1->getType()); // too big shift is poison
|
|
case Instruction::LShr:
|
|
if (C2V.ult(C1V.getBitWidth()))
|
|
return ConstantInt::get(CI1->getContext(), C1V.lshr(C2V));
|
|
return PoisonValue::get(C1->getType()); // too big shift is poison
|
|
case Instruction::AShr:
|
|
if (C2V.ult(C1V.getBitWidth()))
|
|
return ConstantInt::get(CI1->getContext(), C1V.ashr(C2V));
|
|
return PoisonValue::get(C1->getType()); // too big shift is poison
|
|
}
|
|
}
|
|
|
|
switch (Opcode) {
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
case Instruction::Shl:
|
|
if (CI1->isZero()) return C1;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
} else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
|
|
if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
|
|
const APFloat &C1V = CFP1->getValueAPF();
|
|
const APFloat &C2V = CFP2->getValueAPF();
|
|
APFloat C3V = C1V; // copy for modification
|
|
switch (Opcode) {
|
|
default:
|
|
break;
|
|
case Instruction::FAdd:
|
|
(void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C1->getContext(), C3V);
|
|
case Instruction::FSub:
|
|
(void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C1->getContext(), C3V);
|
|
case Instruction::FMul:
|
|
(void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C1->getContext(), C3V);
|
|
case Instruction::FDiv:
|
|
(void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
|
|
return ConstantFP::get(C1->getContext(), C3V);
|
|
case Instruction::FRem:
|
|
(void)C3V.mod(C2V);
|
|
return ConstantFP::get(C1->getContext(), C3V);
|
|
}
|
|
}
|
|
} else if (auto *VTy = dyn_cast<VectorType>(C1->getType())) {
|
|
// Fast path for splatted constants.
|
|
if (Constant *C2Splat = C2->getSplatValue()) {
|
|
if (Instruction::isIntDivRem(Opcode) && C2Splat->isNullValue())
|
|
return PoisonValue::get(VTy);
|
|
if (Constant *C1Splat = C1->getSplatValue()) {
|
|
return ConstantVector::getSplat(
|
|
VTy->getElementCount(),
|
|
ConstantExpr::get(Opcode, C1Splat, C2Splat));
|
|
}
|
|
}
|
|
|
|
if (auto *FVTy = dyn_cast<FixedVectorType>(VTy)) {
|
|
// Fold each element and create a vector constant from those constants.
|
|
SmallVector<Constant*, 16> Result;
|
|
Type *Ty = IntegerType::get(FVTy->getContext(), 32);
|
|
for (unsigned i = 0, e = FVTy->getNumElements(); i != e; ++i) {
|
|
Constant *ExtractIdx = ConstantInt::get(Ty, i);
|
|
Constant *LHS = ConstantExpr::getExtractElement(C1, ExtractIdx);
|
|
Constant *RHS = ConstantExpr::getExtractElement(C2, ExtractIdx);
|
|
|
|
// If any element of a divisor vector is zero, the whole op is poison.
|
|
if (Instruction::isIntDivRem(Opcode) && RHS->isNullValue())
|
|
return PoisonValue::get(VTy);
|
|
|
|
Result.push_back(ConstantExpr::get(Opcode, LHS, RHS));
|
|
}
|
|
|
|
return ConstantVector::get(Result);
|
|
}
|
|
}
|
|
|
|
if (ConstantExpr *CE1 = dyn_cast<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.
|
|
|
|
// Given ((a + b) + c), if (b + c) folds to something interesting, return
|
|
// (a + (b + c)).
|
|
if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) {
|
|
Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2);
|
|
if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode)
|
|
return ConstantExpr::get(Opcode, CE1->getOperand(0), T);
|
|
}
|
|
} 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.
|
|
if (Instruction::isCommutative(Opcode))
|
|
return ConstantFoldBinaryInstruction(Opcode, C2, C1);
|
|
}
|
|
|
|
// i1 can be simplified in many cases.
|
|
if (C1->getType()->isIntegerTy(1)) {
|
|
switch (Opcode) {
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
return ConstantExpr::getXor(C1, C2);
|
|
case Instruction::Mul:
|
|
return ConstantExpr::getAnd(C1, C2);
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
// We can assume that C2 == 0. If it were one the result would be
|
|
// undefined because the shift value is as large as the bitwidth.
|
|
return C1;
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
// We can assume that C2 == 1. If it were zero the result would be
|
|
// undefined through division by zero.
|
|
return C1;
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
// We can assume that C2 == 1. If it were zero the result would be
|
|
// undefined through division by zero.
|
|
return ConstantInt::getFalse(C1->getContext());
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
// We don't know how to fold this.
|
|
return nullptr;
|
|
}
|
|
|
|
/// This type is zero-sized if it's an array or structure of zero-sized types.
|
|
/// The only leaf zero-sized type is an empty structure.
|
|
static bool isMaybeZeroSizedType(Type *Ty) {
|
|
if (StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
if (STy->isOpaque()) return true; // Can't say.
|
|
|
|
// 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 (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
|
|
return isMaybeZeroSizedType(ATy->getElementType());
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// Compare the two constants as though they were getelementptr indices.
|
|
/// This allows coercion of the types to be the same thing.
|
|
///
|
|
/// If the two constants are the "same" (after coercion), 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, 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!
|
|
|
|
// We cannot compare the indices if they don't fit in an int64_t.
|
|
if (cast<ConstantInt>(C1)->getValue().getActiveBits() > 64 ||
|
|
cast<ConstantInt>(C2)->getValue().getActiveBits() > 64)
|
|
return -2; // don't know!
|
|
|
|
// Ok, we have two differing integer indices. Sign extend them to be the same
|
|
// type.
|
|
int64_t C1Val = cast<ConstantInt>(C1)->getSExtValue();
|
|
int64_t C2Val = cast<ConstantInt>(C2)->getSExtValue();
|
|
|
|
if (C1Val == C2Val) 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 (C1Val < C2Val)
|
|
return -1;
|
|
else
|
|
return 1;
|
|
}
|
|
|
|
/// 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(Constant *V1, Constant *V2) {
|
|
assert(V1->getType() == V2->getType() &&
|
|
"Cannot compare values of different types!");
|
|
|
|
// We do not know if a constant expression will evaluate to a number or NaN.
|
|
// Therefore, we can only say that the relation is unordered or equal.
|
|
if (V1 == V2) return FCmpInst::FCMP_UEQ;
|
|
|
|
if (!isa<ConstantExpr>(V1)) {
|
|
if (!isa<ConstantExpr>(V2)) {
|
|
// Simple case, use the standard constant folder.
|
|
ConstantInt *R = nullptr;
|
|
R = dyn_cast<ConstantInt>(
|
|
ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2));
|
|
if (R && !R->isZero())
|
|
return FCmpInst::FCMP_OEQ;
|
|
R = dyn_cast<ConstantInt>(
|
|
ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2));
|
|
if (R && !R->isZero())
|
|
return FCmpInst::FCMP_OLT;
|
|
R = dyn_cast<ConstantInt>(
|
|
ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2));
|
|
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.
|
|
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;
|
|
}
|
|
|
|
static ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1,
|
|
const GlobalValue *GV2) {
|
|
auto isGlobalUnsafeForEquality = [](const GlobalValue *GV) {
|
|
if (GV->isInterposable() || GV->hasGlobalUnnamedAddr())
|
|
return true;
|
|
if (const auto *GVar = dyn_cast<GlobalVariable>(GV)) {
|
|
Type *Ty = GVar->getValueType();
|
|
// A global with opaque type might end up being zero sized.
|
|
if (!Ty->isSized())
|
|
return true;
|
|
// A global with an empty type might lie at the address of any other
|
|
// global.
|
|
if (Ty->isEmptyTy())
|
|
return true;
|
|
}
|
|
return false;
|
|
};
|
|
// Don't try to decide equality of aliases.
|
|
if (!isa<GlobalAlias>(GV1) && !isa<GlobalAlias>(GV2))
|
|
if (!isGlobalUnsafeForEquality(GV1) && !isGlobalUnsafeForEquality(GV2))
|
|
return ICmpInst::ICMP_NE;
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
/// 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(Constant *V1, 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) &&
|
|
!isa<BlockAddress>(V1)) {
|
|
if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) &&
|
|
!isa<BlockAddress>(V2)) {
|
|
// We distilled this down to a simple case, use the standard constant
|
|
// folder.
|
|
ConstantInt *R = nullptr;
|
|
ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
|
|
R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2));
|
|
if (R && !R->isZero())
|
|
return pred;
|
|
pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
|
|
R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2));
|
|
if (R && !R->isZero())
|
|
return pred;
|
|
pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
|
|
R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2));
|
|
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 *GV = 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);
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
// Now we know that the RHS is a GlobalValue, BlockAddress or simple
|
|
// constant (which, since the types must match, means that it's a
|
|
// ConstantPointerNull).
|
|
if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) {
|
|
return areGlobalsPotentiallyEqual(GV, GV2);
|
|
} else if (isa<BlockAddress>(V2)) {
|
|
return ICmpInst::ICMP_NE; // Globals never equal labels.
|
|
} else {
|
|
assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
|
|
// GlobalVals can never be null unless they have external weak linkage.
|
|
// We don't try to evaluate aliases here.
|
|
// NOTE: We should not be doing this constant folding if null pointer
|
|
// is considered valid for the function. But currently there is no way to
|
|
// query it from the Constant type.
|
|
if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV) &&
|
|
!NullPointerIsDefined(nullptr /* F */,
|
|
GV->getType()->getAddressSpace()))
|
|
return ICmpInst::ICMP_UGT;
|
|
}
|
|
} else if (const BlockAddress *BA = dyn_cast<BlockAddress>(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);
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
// Now we know that the RHS is a GlobalValue, BlockAddress or simple
|
|
// constant (which, since the types must match, means that it is a
|
|
// ConstantPointerNull).
|
|
if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) {
|
|
// Block address in another function can't equal this one, but block
|
|
// addresses in the current function might be the same if blocks are
|
|
// empty.
|
|
if (BA2->getFunction() != BA->getFunction())
|
|
return ICmpInst::ICMP_NE;
|
|
} else {
|
|
// Block addresses aren't null, don't equal the address of globals.
|
|
assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) &&
|
|
"Canonicalization guarantee!");
|
|
return ICmpInst::ICMP_NE;
|
|
}
|
|
} else {
|
|
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
|
|
// constantexpr, a global, block address, or a simple constant.
|
|
ConstantExpr *CE1 = cast<ConstantExpr>(V1);
|
|
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::BitCast:
|
|
// If this is a global value cast, check to see if the RHS is also a
|
|
// GlobalValue.
|
|
if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0))
|
|
if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2))
|
|
return areGlobalsPotentiallyEqual(GV, GV2);
|
|
LLVM_FALLTHROUGH;
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
// We can't evaluate floating point casts or truncations.
|
|
if (CE1Op0->getType()->isFPOrFPVectorTy())
|
|
break;
|
|
|
|
// 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() && CE1->getType()->isIntOrPtrTy()) {
|
|
if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
|
|
if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
|
|
return evaluateICmpRelation(CE1Op0,
|
|
Constant::getNullValue(CE1Op0->getType()),
|
|
isSigned);
|
|
}
|
|
break;
|
|
|
|
case Instruction::GetElementPtr: {
|
|
GEPOperator *CE1GEP = cast<GEPOperator>(CE1);
|
|
// 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 its not weak linkage, the GVal must have a non-zero address
|
|
// so the result is greater-than
|
|
if (!GV->hasExternalWeakLinkage())
|
|
return 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 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 *GV2 = dyn_cast<GlobalValue>(V2)) {
|
|
if (isa<ConstantPointerNull>(CE1Op0)) {
|
|
// If its not weak linkage, the GVal must have a non-zero address
|
|
// so the result is less-than
|
|
if (!GV2->hasExternalWeakLinkage())
|
|
return ICmpInst::ICMP_ULT;
|
|
} else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
|
|
if (GV == GV2) {
|
|
// 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() &&
|
|
"Surprising getelementptr!");
|
|
return ICmpInst::ICMP_UGT;
|
|
} else {
|
|
if (CE1GEP->hasAllZeroIndices())
|
|
return areGlobalsPotentiallyEqual(GV, GV2);
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
}
|
|
} else {
|
|
ConstantExpr *CE2 = cast<ConstantExpr>(V2);
|
|
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 global.
|
|
if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
|
|
// Don't know relative ordering, but check for inequality.
|
|
if (CE1Op0 != CE2Op0) {
|
|
GEPOperator *CE2GEP = cast<GEPOperator>(CE2);
|
|
if (CE1GEP->hasAllZeroIndices() && CE2GEP->hasAllZeroIndices())
|
|
return areGlobalsPotentiallyEqual(cast<GlobalValue>(CE1Op0),
|
|
cast<GlobalValue>(CE2Op0));
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
// 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;
|
|
|
|
// The logic below assumes that the result of the comparison
|
|
// can be determined by finding the first index that differs.
|
|
// This doesn't work if there is over-indexing in any
|
|
// subsequent indices, so check for that case first.
|
|
if (!CE1->isGEPWithNoNotionalOverIndexing() ||
|
|
!CE2->isGEPWithNoNotionalOverIndexing())
|
|
return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
|
|
|
|
// 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;
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
return ICmpInst::BAD_ICMP_PREDICATE;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
|
|
Constant *C1, Constant *C2) {
|
|
Type *ResultTy;
|
|
if (VectorType *VT = dyn_cast<VectorType>(C1->getType()))
|
|
ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()),
|
|
VT->getElementCount());
|
|
else
|
|
ResultTy = Type::getInt1Ty(C1->getContext());
|
|
|
|
// Fold FCMP_FALSE/FCMP_TRUE unconditionally.
|
|
if (pred == FCmpInst::FCMP_FALSE)
|
|
return Constant::getNullValue(ResultTy);
|
|
|
|
if (pred == FCmpInst::FCMP_TRUE)
|
|
return Constant::getAllOnesValue(ResultTy);
|
|
|
|
// Handle some degenerate cases first
|
|
if (isa<PoisonValue>(C1) || isa<PoisonValue>(C2))
|
|
return PoisonValue::get(ResultTy);
|
|
|
|
if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
|
|
CmpInst::Predicate Predicate = CmpInst::Predicate(pred);
|
|
bool isIntegerPredicate = ICmpInst::isIntPredicate(Predicate);
|
|
// For EQ and NE, we can always pick a value for the undef to make the
|
|
// predicate pass or fail, so we can return undef.
|
|
// Also, if both operands are undef, we can return undef for int comparison.
|
|
if (ICmpInst::isEquality(Predicate) || (isIntegerPredicate && C1 == C2))
|
|
return UndefValue::get(ResultTy);
|
|
|
|
// Otherwise, for integer compare, pick the same value as the non-undef
|
|
// operand, and fold it to true or false.
|
|
if (isIntegerPredicate)
|
|
return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(Predicate));
|
|
|
|
// Choosing NaN for the undef will always make unordered comparison succeed
|
|
// and ordered comparison fails.
|
|
return ConstantInt::get(ResultTy, CmpInst::isUnordered(Predicate));
|
|
}
|
|
|
|
// 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() &&
|
|
!NullPointerIsDefined(nullptr /* F */,
|
|
GV->getType()->getAddressSpace())) {
|
|
if (pred == ICmpInst::ICMP_EQ)
|
|
return ConstantInt::getFalse(C1->getContext());
|
|
else if (pred == ICmpInst::ICMP_NE)
|
|
return ConstantInt::getTrue(C1->getContext());
|
|
}
|
|
// 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() &&
|
|
!NullPointerIsDefined(nullptr /* F */,
|
|
GV->getType()->getAddressSpace())) {
|
|
if (pred == ICmpInst::ICMP_EQ)
|
|
return ConstantInt::getFalse(C1->getContext());
|
|
else if (pred == ICmpInst::ICMP_NE)
|
|
return ConstantInt::getTrue(C1->getContext());
|
|
}
|
|
}
|
|
|
|
// The caller is expected to commute the operands if the constant expression
|
|
// is C2.
|
|
// C1 >= 0 --> true
|
|
if (pred == ICmpInst::ICMP_UGE)
|
|
return Constant::getAllOnesValue(ResultTy);
|
|
// C1 < 0 --> false
|
|
if (pred == ICmpInst::ICMP_ULT)
|
|
return Constant::getNullValue(ResultTy);
|
|
}
|
|
|
|
// If the comparison is a comparison between two i1's, simplify it.
|
|
if (C1->getType()->isIntegerTy(1)) {
|
|
switch(pred) {
|
|
case ICmpInst::ICMP_EQ:
|
|
if (isa<ConstantInt>(C2))
|
|
return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2));
|
|
return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2);
|
|
case ICmpInst::ICMP_NE:
|
|
return ConstantExpr::getXor(C1, C2);
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
|
|
const APInt &V1 = cast<ConstantInt>(C1)->getValue();
|
|
const APInt &V2 = cast<ConstantInt>(C2)->getValue();
|
|
switch (pred) {
|
|
default: llvm_unreachable("Invalid ICmp Predicate");
|
|
case ICmpInst::ICMP_EQ: return ConstantInt::get(ResultTy, V1 == V2);
|
|
case ICmpInst::ICMP_NE: return ConstantInt::get(ResultTy, V1 != V2);
|
|
case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2));
|
|
case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2));
|
|
case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2));
|
|
case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2));
|
|
case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2));
|
|
case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2));
|
|
case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2));
|
|
case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2));
|
|
}
|
|
} else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
|
|
const APFloat &C1V = cast<ConstantFP>(C1)->getValueAPF();
|
|
const APFloat &C2V = cast<ConstantFP>(C2)->getValueAPF();
|
|
APFloat::cmpResult R = C1V.compare(C2V);
|
|
switch (pred) {
|
|
default: llvm_unreachable("Invalid FCmp Predicate");
|
|
case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy);
|
|
case FCmpInst::FCMP_TRUE: return Constant::getAllOnesValue(ResultTy);
|
|
case FCmpInst::FCMP_UNO:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered);
|
|
case FCmpInst::FCMP_ORD:
|
|
return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered);
|
|
case FCmpInst::FCMP_UEQ:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered ||
|
|
R==APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_OEQ:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_UNE:
|
|
return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_ONE:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan ||
|
|
R==APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_ULT:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered ||
|
|
R==APFloat::cmpLessThan);
|
|
case FCmpInst::FCMP_OLT:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan);
|
|
case FCmpInst::FCMP_UGT:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered ||
|
|
R==APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_OGT:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_ULE:
|
|
return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan);
|
|
case FCmpInst::FCMP_OLE:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan ||
|
|
R==APFloat::cmpEqual);
|
|
case FCmpInst::FCMP_UGE:
|
|
return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan);
|
|
case FCmpInst::FCMP_OGE:
|
|
return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan ||
|
|
R==APFloat::cmpEqual);
|
|
}
|
|
} else if (auto *C1VTy = dyn_cast<VectorType>(C1->getType())) {
|
|
|
|
// Fast path for splatted constants.
|
|
if (Constant *C1Splat = C1->getSplatValue())
|
|
if (Constant *C2Splat = C2->getSplatValue())
|
|
return ConstantVector::getSplat(
|
|
C1VTy->getElementCount(),
|
|
ConstantExpr::getCompare(pred, C1Splat, C2Splat));
|
|
|
|
// Do not iterate on scalable vector. The number of elements is unknown at
|
|
// compile-time.
|
|
if (isa<ScalableVectorType>(C1VTy))
|
|
return nullptr;
|
|
|
|
// If we can constant fold the comparison of each element, constant fold
|
|
// the whole vector comparison.
|
|
SmallVector<Constant*, 4> ResElts;
|
|
Type *Ty = IntegerType::get(C1->getContext(), 32);
|
|
// Compare the elements, producing an i1 result or constant expr.
|
|
for (unsigned I = 0, E = C1VTy->getElementCount().getKnownMinValue();
|
|
I != E; ++I) {
|
|
Constant *C1E =
|
|
ConstantExpr::getExtractElement(C1, ConstantInt::get(Ty, I));
|
|
Constant *C2E =
|
|
ConstantExpr::getExtractElement(C2, ConstantInt::get(Ty, I));
|
|
|
|
ResElts.push_back(ConstantExpr::getCompare(pred, C1E, C2E));
|
|
}
|
|
|
|
return ConstantVector::get(ResElts);
|
|
}
|
|
|
|
if (C1->getType()->isFloatingPointTy() &&
|
|
// Only call evaluateFCmpRelation if we have a constant expr to avoid
|
|
// infinite recursive loop
|
|
(isa<ConstantExpr>(C1) || isa<ConstantExpr>(C2))) {
|
|
int Result = -1; // -1 = unknown, 0 = known false, 1 = known true.
|
|
switch (evaluateFCmpRelation(C1, C2)) {
|
|
default: llvm_unreachable("Unknown relation!");
|
|
case FCmpInst::FCMP_UNO:
|
|
case FCmpInst::FCMP_ORD:
|
|
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 FCmpInst::FCMP_ONE: // 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;
|
|
case FCmpInst::FCMP_UEQ: // We know that C1 == C2 || isUnordered(C1, C2).
|
|
// We can only partially decide this relation.
|
|
if (pred == FCmpInst::FCMP_ONE)
|
|
Result = 0;
|
|
else if (pred == FCmpInst::FCMP_UEQ)
|
|
Result = 1;
|
|
break;
|
|
}
|
|
|
|
// If we evaluated the result, return it now.
|
|
if (Result != -1)
|
|
return ConstantInt::get(ResultTy, 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((CmpInst::Predicate)pred))) {
|
|
default: llvm_unreachable("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 = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred);
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
switch (pred) {
|
|
case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE:
|
|
Result = 1; break;
|
|
case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE:
|
|
Result = 0; break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
switch (pred) {
|
|
case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE:
|
|
Result = 1; break;
|
|
case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE:
|
|
Result = 0; break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
switch (pred) {
|
|
case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE:
|
|
Result = 1; break;
|
|
case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE:
|
|
Result = 0; break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
switch (pred) {
|
|
case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE:
|
|
Result = 1; break;
|
|
case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE:
|
|
Result = 0; break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_ULE:
|
|
if (pred == ICmpInst::ICMP_UGT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_SLE:
|
|
if (pred == ICmpInst::ICMP_SGT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_UGE:
|
|
if (pred == ICmpInst::ICMP_ULT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_SGE:
|
|
if (pred == ICmpInst::ICMP_SLT) Result = 0;
|
|
if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1;
|
|
break;
|
|
case ICmpInst::ICMP_NE:
|
|
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)
|
|
return ConstantInt::get(ResultTy, Result);
|
|
|
|
// If the right hand side is a bitcast, try using its inverse to simplify
|
|
// it by moving it to the left hand side. We can't do this if it would turn
|
|
// a vector compare into a scalar compare or visa versa, or if it would turn
|
|
// the operands into FP values.
|
|
if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) {
|
|
Constant *CE2Op0 = CE2->getOperand(0);
|
|
if (CE2->getOpcode() == Instruction::BitCast &&
|
|
CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy() &&
|
|
!CE2Op0->getType()->isFPOrFPVectorTy()) {
|
|
Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType());
|
|
return ConstantExpr::getICmp(pred, Inverse, CE2Op0);
|
|
}
|
|
}
|
|
|
|
// If the left hand side is an extension, try eliminating it.
|
|
if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
|
|
if ((CE1->getOpcode() == Instruction::SExt &&
|
|
ICmpInst::isSigned((ICmpInst::Predicate)pred)) ||
|
|
(CE1->getOpcode() == Instruction::ZExt &&
|
|
!ICmpInst::isSigned((ICmpInst::Predicate)pred))){
|
|
Constant *CE1Op0 = CE1->getOperand(0);
|
|
Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType());
|
|
if (CE1Inverse == CE1Op0) {
|
|
// Check whether we can safely truncate the right hand side.
|
|
Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType());
|
|
if (ConstantExpr::getCast(CE1->getOpcode(), C2Inverse,
|
|
C2->getType()) == C2)
|
|
return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse);
|
|
}
|
|
}
|
|
}
|
|
|
|
if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) ||
|
|
(C1->isNullValue() && !C2->isNullValue())) {
|
|
// If C2 is a constant expr and C1 isn't, flip them around and fold the
|
|
// other way if possible.
|
|
// Also, if C1 is null and C2 isn't, flip them around.
|
|
pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
|
|
return ConstantExpr::getICmp(pred, C2, C1);
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
/// Test whether the given sequence of *normalized* indices is "inbounds".
|
|
template<typename IndexTy>
|
|
static bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) {
|
|
// No indices means nothing that could be out of bounds.
|
|
if (Idxs.empty()) return true;
|
|
|
|
// If the first index is zero, it's in bounds.
|
|
if (cast<Constant>(Idxs[0])->isNullValue()) return true;
|
|
|
|
// If the first index is one and all the rest are zero, it's in bounds,
|
|
// by the one-past-the-end rule.
|
|
if (auto *CI = dyn_cast<ConstantInt>(Idxs[0])) {
|
|
if (!CI->isOne())
|
|
return false;
|
|
} else {
|
|
auto *CV = cast<ConstantDataVector>(Idxs[0]);
|
|
CI = dyn_cast_or_null<ConstantInt>(CV->getSplatValue());
|
|
if (!CI || !CI->isOne())
|
|
return false;
|
|
}
|
|
|
|
for (unsigned i = 1, e = Idxs.size(); i != e; ++i)
|
|
if (!cast<Constant>(Idxs[i])->isNullValue())
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/// Test whether a given ConstantInt is in-range for a SequentialType.
|
|
static bool isIndexInRangeOfArrayType(uint64_t NumElements,
|
|
const ConstantInt *CI) {
|
|
// We cannot bounds check the index if it doesn't fit in an int64_t.
|
|
if (CI->getValue().getMinSignedBits() > 64)
|
|
return false;
|
|
|
|
// A negative index or an index past the end of our sequential type is
|
|
// considered out-of-range.
|
|
int64_t IndexVal = CI->getSExtValue();
|
|
if (IndexVal < 0 || (NumElements > 0 && (uint64_t)IndexVal >= NumElements))
|
|
return false;
|
|
|
|
// Otherwise, it is in-range.
|
|
return true;
|
|
}
|
|
|
|
Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C,
|
|
bool InBounds,
|
|
Optional<unsigned> InRangeIndex,
|
|
ArrayRef<Value *> Idxs) {
|
|
if (Idxs.empty()) return C;
|
|
|
|
Type *GEPTy = GetElementPtrInst::getGEPReturnType(
|
|
PointeeTy, C, makeArrayRef((Value *const *)Idxs.data(), Idxs.size()));
|
|
|
|
if (isa<PoisonValue>(C))
|
|
return PoisonValue::get(GEPTy);
|
|
|
|
if (isa<UndefValue>(C))
|
|
// If inbounds, we can choose an out-of-bounds pointer as a base pointer.
|
|
return InBounds ? PoisonValue::get(GEPTy) : UndefValue::get(GEPTy);
|
|
|
|
Constant *Idx0 = cast<Constant>(Idxs[0]);
|
|
if (Idxs.size() == 1 && (Idx0->isNullValue() || isa<UndefValue>(Idx0)))
|
|
return GEPTy->isVectorTy() && !C->getType()->isVectorTy()
|
|
? ConstantVector::getSplat(
|
|
cast<VectorType>(GEPTy)->getElementCount(), C)
|
|
: C;
|
|
|
|
if (C->isNullValue()) {
|
|
bool isNull = true;
|
|
for (unsigned i = 0, e = Idxs.size(); i != e; ++i)
|
|
if (!isa<UndefValue>(Idxs[i]) &&
|
|
!cast<Constant>(Idxs[i])->isNullValue()) {
|
|
isNull = false;
|
|
break;
|
|
}
|
|
if (isNull) {
|
|
PointerType *PtrTy = cast<PointerType>(C->getType()->getScalarType());
|
|
Type *Ty = GetElementPtrInst::getIndexedType(PointeeTy, Idxs);
|
|
|
|
assert(Ty && "Invalid indices for GEP!");
|
|
Type *OrigGEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
|
|
Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
|
|
if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
|
|
GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount());
|
|
|
|
// The GEP returns a vector of pointers when one of more of
|
|
// its arguments is a vector.
|
|
for (unsigned i = 0, e = Idxs.size(); i != e; ++i) {
|
|
if (auto *VT = dyn_cast<VectorType>(Idxs[i]->getType())) {
|
|
assert((!isa<VectorType>(GEPTy) || isa<ScalableVectorType>(GEPTy) ==
|
|
isa<ScalableVectorType>(VT)) &&
|
|
"Mismatched GEPTy vector types");
|
|
GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount());
|
|
break;
|
|
}
|
|
}
|
|
|
|
return Constant::getNullValue(GEPTy);
|
|
}
|
|
}
|
|
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(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) {
|
|
gep_type_iterator LastI = gep_type_end(CE);
|
|
for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
|
|
I != E; ++I)
|
|
LastI = I;
|
|
|
|
// We cannot combine indices if doing so would take us outside of an
|
|
// array or vector. Doing otherwise could trick us if we evaluated such a
|
|
// GEP as part of a load.
|
|
//
|
|
// e.g. Consider if the original GEP was:
|
|
// i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c,
|
|
// i32 0, i32 0, i64 0)
|
|
//
|
|
// If we then tried to offset it by '8' to get to the third element,
|
|
// an i8, we should *not* get:
|
|
// i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c,
|
|
// i32 0, i32 0, i64 8)
|
|
//
|
|
// This GEP tries to index array element '8 which runs out-of-bounds.
|
|
// Subsequent evaluation would get confused and produce erroneous results.
|
|
//
|
|
// The following prohibits such a GEP from being formed by checking to see
|
|
// if the index is in-range with respect to an array.
|
|
// TODO: This code may be extended to handle vectors as well.
|
|
bool PerformFold = false;
|
|
if (Idx0->isNullValue())
|
|
PerformFold = true;
|
|
else if (LastI.isSequential())
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx0))
|
|
PerformFold = (!LastI.isBoundedSequential() ||
|
|
isIndexInRangeOfArrayType(
|
|
LastI.getSequentialNumElements(), CI)) &&
|
|
!CE->getOperand(CE->getNumOperands() - 1)
|
|
->getType()
|
|
->isVectorTy();
|
|
|
|
if (PerformFold) {
|
|
SmallVector<Value*, 16> NewIndices;
|
|
NewIndices.reserve(Idxs.size() + CE->getNumOperands());
|
|
NewIndices.append(CE->op_begin() + 1, CE->op_end() - 1);
|
|
|
|
// 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()) {
|
|
Type *IdxTy = Combined->getType();
|
|
if (IdxTy != Idx0->getType()) {
|
|
unsigned CommonExtendedWidth =
|
|
std::max(IdxTy->getIntegerBitWidth(),
|
|
Idx0->getType()->getIntegerBitWidth());
|
|
CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);
|
|
|
|
Type *CommonTy =
|
|
Type::getIntNTy(IdxTy->getContext(), CommonExtendedWidth);
|
|
Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, CommonTy);
|
|
Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, CommonTy);
|
|
Combined = ConstantExpr::get(Instruction::Add, C1, C2);
|
|
} else {
|
|
Combined =
|
|
ConstantExpr::get(Instruction::Add, Idx0, Combined);
|
|
}
|
|
}
|
|
|
|
NewIndices.push_back(Combined);
|
|
NewIndices.append(Idxs.begin() + 1, Idxs.end());
|
|
|
|
// The combined GEP normally inherits its index inrange attribute from
|
|
// the inner GEP, but if the inner GEP's last index was adjusted by the
|
|
// outer GEP, any inbounds attribute on that index is invalidated.
|
|
Optional<unsigned> IRIndex = cast<GEPOperator>(CE)->getInRangeIndex();
|
|
if (IRIndex && *IRIndex == CE->getNumOperands() - 2 && !Idx0->isNullValue())
|
|
IRIndex = None;
|
|
|
|
return ConstantExpr::getGetElementPtr(
|
|
cast<GEPOperator>(CE)->getSourceElementType(), CE->getOperand(0),
|
|
NewIndices, InBounds && cast<GEPOperator>(CE)->isInBounds(),
|
|
IRIndex);
|
|
}
|
|
}
|
|
|
|
// Attempt to fold casts to the same type away. For example, folding:
|
|
//
|
|
// i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*),
|
|
// i64 0, i64 0)
|
|
// into:
|
|
//
|
|
// i32* getelementptr ([3 x i32]* %X, i64 0, i64 0)
|
|
//
|
|
// Don't fold if the cast is changing address spaces.
|
|
if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) {
|
|
PointerType *SrcPtrTy =
|
|
dyn_cast<PointerType>(CE->getOperand(0)->getType());
|
|
PointerType *DstPtrTy = dyn_cast<PointerType>(CE->getType());
|
|
if (SrcPtrTy && DstPtrTy) {
|
|
ArrayType *SrcArrayTy =
|
|
dyn_cast<ArrayType>(SrcPtrTy->getElementType());
|
|
ArrayType *DstArrayTy =
|
|
dyn_cast<ArrayType>(DstPtrTy->getElementType());
|
|
if (SrcArrayTy && DstArrayTy
|
|
&& SrcArrayTy->getElementType() == DstArrayTy->getElementType()
|
|
&& SrcPtrTy->getAddressSpace() == DstPtrTy->getAddressSpace())
|
|
return ConstantExpr::getGetElementPtr(SrcArrayTy,
|
|
(Constant *)CE->getOperand(0),
|
|
Idxs, InBounds, InRangeIndex);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check to see if any array indices are not within the corresponding
|
|
// notional array or vector bounds. If so, try to determine if they can be
|
|
// factored out into preceding dimensions.
|
|
SmallVector<Constant *, 8> NewIdxs;
|
|
Type *Ty = PointeeTy;
|
|
Type *Prev = C->getType();
|
|
auto GEPIter = gep_type_begin(PointeeTy, Idxs);
|
|
bool Unknown =
|
|
!isa<ConstantInt>(Idxs[0]) && !isa<ConstantDataVector>(Idxs[0]);
|
|
for (unsigned i = 1, e = Idxs.size(); i != e;
|
|
Prev = Ty, Ty = (++GEPIter).getIndexedType(), ++i) {
|
|
if (!isa<ConstantInt>(Idxs[i]) && !isa<ConstantDataVector>(Idxs[i])) {
|
|
// We don't know if it's in range or not.
|
|
Unknown = true;
|
|
continue;
|
|
}
|
|
if (!isa<ConstantInt>(Idxs[i - 1]) && !isa<ConstantDataVector>(Idxs[i - 1]))
|
|
// Skip if the type of the previous index is not supported.
|
|
continue;
|
|
if (InRangeIndex && i == *InRangeIndex + 1) {
|
|
// If an index is marked inrange, we cannot apply this canonicalization to
|
|
// the following index, as that will cause the inrange index to point to
|
|
// the wrong element.
|
|
continue;
|
|
}
|
|
if (isa<StructType>(Ty)) {
|
|
// The verify makes sure that GEPs into a struct are in range.
|
|
continue;
|
|
}
|
|
if (isa<VectorType>(Ty)) {
|
|
// There can be awkward padding in after a non-power of two vector.
|
|
Unknown = true;
|
|
continue;
|
|
}
|
|
auto *STy = cast<ArrayType>(Ty);
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) {
|
|
if (isIndexInRangeOfArrayType(STy->getNumElements(), CI))
|
|
// It's in range, skip to the next index.
|
|
continue;
|
|
if (CI->getSExtValue() < 0) {
|
|
// It's out of range and negative, don't try to factor it.
|
|
Unknown = true;
|
|
continue;
|
|
}
|
|
} else {
|
|
auto *CV = cast<ConstantDataVector>(Idxs[i]);
|
|
bool InRange = true;
|
|
for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) {
|
|
auto *CI = cast<ConstantInt>(CV->getElementAsConstant(I));
|
|
InRange &= isIndexInRangeOfArrayType(STy->getNumElements(), CI);
|
|
if (CI->getSExtValue() < 0) {
|
|
Unknown = true;
|
|
break;
|
|
}
|
|
}
|
|
if (InRange || Unknown)
|
|
// It's in range, skip to the next index.
|
|
// It's out of range and negative, don't try to factor it.
|
|
continue;
|
|
}
|
|
if (isa<StructType>(Prev)) {
|
|
// It's out of range, but the prior dimension is a struct
|
|
// so we can't do anything about it.
|
|
Unknown = true;
|
|
continue;
|
|
}
|
|
// It's out of range, but we can factor it into the prior
|
|
// dimension.
|
|
NewIdxs.resize(Idxs.size());
|
|
// Determine the number of elements in our sequential type.
|
|
uint64_t NumElements = STy->getArrayNumElements();
|
|
|
|
// Expand the current index or the previous index to a vector from a scalar
|
|
// if necessary.
|
|
Constant *CurrIdx = cast<Constant>(Idxs[i]);
|
|
auto *PrevIdx =
|
|
NewIdxs[i - 1] ? NewIdxs[i - 1] : cast<Constant>(Idxs[i - 1]);
|
|
bool IsCurrIdxVector = CurrIdx->getType()->isVectorTy();
|
|
bool IsPrevIdxVector = PrevIdx->getType()->isVectorTy();
|
|
bool UseVector = IsCurrIdxVector || IsPrevIdxVector;
|
|
|
|
if (!IsCurrIdxVector && IsPrevIdxVector)
|
|
CurrIdx = ConstantDataVector::getSplat(
|
|
cast<FixedVectorType>(PrevIdx->getType())->getNumElements(), CurrIdx);
|
|
|
|
if (!IsPrevIdxVector && IsCurrIdxVector)
|
|
PrevIdx = ConstantDataVector::getSplat(
|
|
cast<FixedVectorType>(CurrIdx->getType())->getNumElements(), PrevIdx);
|
|
|
|
Constant *Factor =
|
|
ConstantInt::get(CurrIdx->getType()->getScalarType(), NumElements);
|
|
if (UseVector)
|
|
Factor = ConstantDataVector::getSplat(
|
|
IsPrevIdxVector
|
|
? cast<FixedVectorType>(PrevIdx->getType())->getNumElements()
|
|
: cast<FixedVectorType>(CurrIdx->getType())->getNumElements(),
|
|
Factor);
|
|
|
|
NewIdxs[i] = ConstantExpr::getSRem(CurrIdx, Factor);
|
|
|
|
Constant *Div = ConstantExpr::getSDiv(CurrIdx, Factor);
|
|
|
|
unsigned CommonExtendedWidth =
|
|
std::max(PrevIdx->getType()->getScalarSizeInBits(),
|
|
Div->getType()->getScalarSizeInBits());
|
|
CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);
|
|
|
|
// Before adding, extend both operands to i64 to avoid
|
|
// overflow trouble.
|
|
Type *ExtendedTy = Type::getIntNTy(Div->getContext(), CommonExtendedWidth);
|
|
if (UseVector)
|
|
ExtendedTy = FixedVectorType::get(
|
|
ExtendedTy,
|
|
IsPrevIdxVector
|
|
? cast<FixedVectorType>(PrevIdx->getType())->getNumElements()
|
|
: cast<FixedVectorType>(CurrIdx->getType())->getNumElements());
|
|
|
|
if (!PrevIdx->getType()->isIntOrIntVectorTy(CommonExtendedWidth))
|
|
PrevIdx = ConstantExpr::getSExt(PrevIdx, ExtendedTy);
|
|
|
|
if (!Div->getType()->isIntOrIntVectorTy(CommonExtendedWidth))
|
|
Div = ConstantExpr::getSExt(Div, ExtendedTy);
|
|
|
|
NewIdxs[i - 1] = ConstantExpr::getAdd(PrevIdx, Div);
|
|
}
|
|
|
|
// If we did any factoring, start over with the adjusted indices.
|
|
if (!NewIdxs.empty()) {
|
|
for (unsigned i = 0, e = Idxs.size(); i != e; ++i)
|
|
if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]);
|
|
return ConstantExpr::getGetElementPtr(PointeeTy, C, NewIdxs, InBounds,
|
|
InRangeIndex);
|
|
}
|
|
|
|
// If all indices are known integers and normalized, we can do a simple
|
|
// check for the "inbounds" property.
|
|
if (!Unknown && !InBounds)
|
|
if (auto *GV = dyn_cast<GlobalVariable>(C))
|
|
if (!GV->hasExternalWeakLinkage() && isInBoundsIndices(Idxs))
|
|
return ConstantExpr::getGetElementPtr(PointeeTy, C, Idxs,
|
|
/*InBounds=*/true, InRangeIndex);
|
|
|
|
return nullptr;
|
|
}
|