b21e328286
For getelementptr i8 (aka ptradd) we can skip the whole logic and directly use the offset. As we're now canonicalizing to this form, it's pretty common and worth having a fast-path for.
267 lines
9.4 KiB
C++
267 lines
9.4 KiB
C++
//===-- Operator.cpp - Implement the LLVM operators -----------------------===//
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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 the non-inline methods for the LLVM Operator classes.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/IR/Operator.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/GetElementPtrTypeIterator.h"
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#include "llvm/IR/Instructions.h"
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#include "ConstantsContext.h"
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namespace llvm {
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bool Operator::hasPoisonGeneratingFlags() const {
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switch (getOpcode()) {
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case Instruction::Add:
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case Instruction::Sub:
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case Instruction::Mul:
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case Instruction::Shl: {
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auto *OBO = cast<OverflowingBinaryOperator>(this);
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return OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap();
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}
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case Instruction::UDiv:
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case Instruction::SDiv:
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case Instruction::AShr:
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case Instruction::LShr:
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return cast<PossiblyExactOperator>(this)->isExact();
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case Instruction::Or:
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return cast<PossiblyDisjointInst>(this)->isDisjoint();
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case Instruction::GetElementPtr: {
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auto *GEP = cast<GEPOperator>(this);
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// Note: inrange exists on constexpr only
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return GEP->isInBounds() || GEP->getInRangeIndex() != std::nullopt;
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}
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case Instruction::ZExt:
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if (auto *NNI = dyn_cast<PossiblyNonNegInst>(this))
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return NNI->hasNonNeg();
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return false;
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default:
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if (const auto *FP = dyn_cast<FPMathOperator>(this))
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return FP->hasNoNaNs() || FP->hasNoInfs();
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return false;
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}
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}
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bool Operator::hasPoisonGeneratingFlagsOrMetadata() const {
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if (hasPoisonGeneratingFlags())
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return true;
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auto *I = dyn_cast<Instruction>(this);
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return I && I->hasPoisonGeneratingMetadata();
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}
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Type *GEPOperator::getSourceElementType() const {
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if (auto *I = dyn_cast<GetElementPtrInst>(this))
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return I->getSourceElementType();
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return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
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}
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Type *GEPOperator::getResultElementType() const {
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if (auto *I = dyn_cast<GetElementPtrInst>(this))
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return I->getResultElementType();
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return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
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}
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Align GEPOperator::getMaxPreservedAlignment(const DataLayout &DL) const {
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/// compute the worse possible offset for every level of the GEP et accumulate
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/// the minimum alignment into Result.
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Align Result = Align(llvm::Value::MaximumAlignment);
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for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
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GTI != GTE; ++GTI) {
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uint64_t Offset;
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ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
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if (StructType *STy = GTI.getStructTypeOrNull()) {
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const StructLayout *SL = DL.getStructLayout(STy);
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Offset = SL->getElementOffset(OpC->getZExtValue());
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} else {
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assert(GTI.isSequential() && "should be sequencial");
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/// If the index isn't known, we take 1 because it is the index that will
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/// give the worse alignment of the offset.
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const uint64_t ElemCount = OpC ? OpC->getZExtValue() : 1;
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Offset = GTI.getSequentialElementStride(DL) * ElemCount;
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}
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Result = Align(MinAlign(Offset, Result.value()));
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}
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return Result;
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}
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bool GEPOperator::accumulateConstantOffset(
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const DataLayout &DL, APInt &Offset,
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function_ref<bool(Value &, APInt &)> ExternalAnalysis) const {
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assert(Offset.getBitWidth() ==
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DL.getIndexSizeInBits(getPointerAddressSpace()) &&
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"The offset bit width does not match DL specification.");
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SmallVector<const Value *> Index(llvm::drop_begin(operand_values()));
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return GEPOperator::accumulateConstantOffset(getSourceElementType(), Index,
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DL, Offset, ExternalAnalysis);
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}
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bool GEPOperator::accumulateConstantOffset(
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Type *SourceType, ArrayRef<const Value *> Index, const DataLayout &DL,
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APInt &Offset, function_ref<bool(Value &, APInt &)> ExternalAnalysis) {
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// Fast path for canonical getelementptr i8 form.
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if (SourceType->isIntegerTy(8) && !ExternalAnalysis) {
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if (auto *CI = dyn_cast<ConstantInt>(Index.front())) {
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Offset += CI->getValue().sextOrTrunc(Offset.getBitWidth());
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return true;
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}
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return false;
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}
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bool UsedExternalAnalysis = false;
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auto AccumulateOffset = [&](APInt Index, uint64_t Size) -> bool {
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Index = Index.sextOrTrunc(Offset.getBitWidth());
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APInt IndexedSize = APInt(Offset.getBitWidth(), Size);
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// For array or vector indices, scale the index by the size of the type.
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if (!UsedExternalAnalysis) {
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Offset += Index * IndexedSize;
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} else {
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// External Analysis can return a result higher/lower than the value
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// represents. We need to detect overflow/underflow.
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bool Overflow = false;
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APInt OffsetPlus = Index.smul_ov(IndexedSize, Overflow);
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if (Overflow)
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return false;
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Offset = Offset.sadd_ov(OffsetPlus, Overflow);
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if (Overflow)
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return false;
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}
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return true;
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};
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auto begin = generic_gep_type_iterator<decltype(Index.begin())>::begin(
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SourceType, Index.begin());
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auto end = generic_gep_type_iterator<decltype(Index.end())>::end(Index.end());
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for (auto GTI = begin, GTE = end; GTI != GTE; ++GTI) {
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// Scalable vectors are multiplied by a runtime constant.
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bool ScalableType = GTI.getIndexedType()->isScalableTy();
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Value *V = GTI.getOperand();
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StructType *STy = GTI.getStructTypeOrNull();
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// Handle ConstantInt if possible.
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if (auto ConstOffset = dyn_cast<ConstantInt>(V)) {
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if (ConstOffset->isZero())
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continue;
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// if the type is scalable and the constant is not zero (vscale * n * 0 =
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// 0) bailout.
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if (ScalableType)
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return false;
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// Handle a struct index, which adds its field offset to the pointer.
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if (STy) {
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unsigned ElementIdx = ConstOffset->getZExtValue();
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const StructLayout *SL = DL.getStructLayout(STy);
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// Element offset is in bytes.
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if (!AccumulateOffset(
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APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx)),
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1))
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return false;
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continue;
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}
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if (!AccumulateOffset(ConstOffset->getValue(),
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GTI.getSequentialElementStride(DL)))
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return false;
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continue;
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}
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// The operand is not constant, check if an external analysis was provided.
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// External analsis is not applicable to a struct type.
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if (!ExternalAnalysis || STy || ScalableType)
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return false;
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APInt AnalysisIndex;
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if (!ExternalAnalysis(*V, AnalysisIndex))
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return false;
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UsedExternalAnalysis = true;
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if (!AccumulateOffset(AnalysisIndex, GTI.getSequentialElementStride(DL)))
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return false;
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}
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return true;
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}
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bool GEPOperator::collectOffset(
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const DataLayout &DL, unsigned BitWidth,
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MapVector<Value *, APInt> &VariableOffsets,
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APInt &ConstantOffset) const {
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assert(BitWidth == DL.getIndexSizeInBits(getPointerAddressSpace()) &&
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"The offset bit width does not match DL specification.");
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auto CollectConstantOffset = [&](APInt Index, uint64_t Size) {
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Index = Index.sextOrTrunc(BitWidth);
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APInt IndexedSize = APInt(BitWidth, Size);
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ConstantOffset += Index * IndexedSize;
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};
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for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
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GTI != GTE; ++GTI) {
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// Scalable vectors are multiplied by a runtime constant.
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bool ScalableType = GTI.getIndexedType()->isScalableTy();
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Value *V = GTI.getOperand();
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StructType *STy = GTI.getStructTypeOrNull();
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// Handle ConstantInt if possible.
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if (auto ConstOffset = dyn_cast<ConstantInt>(V)) {
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if (ConstOffset->isZero())
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continue;
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// If the type is scalable and the constant is not zero (vscale * n * 0 =
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// 0) bailout.
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// TODO: If the runtime value is accessible at any point before DWARF
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// emission, then we could potentially keep a forward reference to it
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// in the debug value to be filled in later.
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if (ScalableType)
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return false;
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// Handle a struct index, which adds its field offset to the pointer.
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if (STy) {
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unsigned ElementIdx = ConstOffset->getZExtValue();
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const StructLayout *SL = DL.getStructLayout(STy);
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// Element offset is in bytes.
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CollectConstantOffset(APInt(BitWidth, SL->getElementOffset(ElementIdx)),
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1);
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continue;
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}
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CollectConstantOffset(ConstOffset->getValue(),
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GTI.getSequentialElementStride(DL));
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continue;
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}
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if (STy || ScalableType)
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return false;
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APInt IndexedSize = APInt(BitWidth, GTI.getSequentialElementStride(DL));
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// Insert an initial offset of 0 for V iff none exists already, then
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// increment the offset by IndexedSize.
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if (!IndexedSize.isZero()) {
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auto *It = VariableOffsets.insert({V, APInt(BitWidth, 0)}).first;
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It->second += IndexedSize;
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}
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}
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return true;
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}
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void FastMathFlags::print(raw_ostream &O) const {
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if (all())
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O << " fast";
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else {
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if (allowReassoc())
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O << " reassoc";
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if (noNaNs())
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O << " nnan";
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if (noInfs())
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O << " ninf";
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if (noSignedZeros())
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O << " nsz";
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if (allowReciprocal())
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O << " arcp";
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if (allowContract())
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O << " contract";
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if (approxFunc())
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O << " afn";
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}
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}
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} // namespace llvm
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