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111 lines
3.9 KiB
C++
111 lines
3.9 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 "llvm/IR/Type.h"
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#include "ConstantsContext.h"
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namespace llvm {
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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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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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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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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 = false;
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if (isa<ScalableVectorType>(GTI.getIndexedType()))
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ScalableType = true;
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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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DL.getTypeAllocSize(GTI.getIndexedType())))
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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,
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DL.getTypeAllocSize(GTI.getIndexedType())))
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return false;
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}
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return true;
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}
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}
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