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//===-- Operator.cpp - Implement the LLVM operators -----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the non-inline methods for the LLVM Operator classes.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/Operator.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Type.h"
#include "ConstantsContext.h"
namespace llvm {
Type *GEPOperator::getSourceElementType() const {
if (auto *I = dyn_cast<GetElementPtrInst>(this))
return I->getSourceElementType();
return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
}
Type *GEPOperator::getResultElementType() const {
if (auto *I = dyn_cast<GetElementPtrInst>(this))
return I->getResultElementType();
return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
}
Align GEPOperator::getMaxPreservedAlignment(const DataLayout &DL) const {
/// compute the worse possible offset for every level of the GEP et accumulate
/// the minimum alignment into Result.
Align Result = Align(llvm::Value::MaximumAlignment);
for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
GTI != GTE; ++GTI) {
int64_t Offset = 1;
ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
if (StructType *STy = GTI.getStructTypeOrNull()) {
const StructLayout *SL = DL.getStructLayout(STy);
Offset = SL->getElementOffset(OpC->getZExtValue());
} else {
assert(GTI.isSequential() && "should be sequencial");
/// If the index isn't know we take 1 because it is the index that will
/// give the worse alignment of the offset.
int64_t ElemCount = 1;
if (OpC)
ElemCount = OpC->getZExtValue();
Offset = DL.getTypeAllocSize(GTI.getIndexedType()) * ElemCount;
}
Result = Align(MinAlign(Offset, Result.value()));
}
return Result;
}
bool GEPOperator::accumulateConstantOffset(
const DataLayout &DL, APInt &Offset,
function_ref<bool(Value &, APInt &)> ExternalAnalysis) const {
assert(Offset.getBitWidth() ==
DL.getIndexSizeInBits(getPointerAddressSpace()) &&
"The offset bit width does not match DL specification.");
SmallVector<const Value *> Index(value_op_begin() + 1, value_op_end());
return GEPOperator::accumulateConstantOffset(getSourceElementType(), Index,
DL, Offset, ExternalAnalysis);
}
bool GEPOperator::accumulateConstantOffset(
Type *SourceType, ArrayRef<const Value *> Index, const DataLayout &DL,
APInt &Offset, function_ref<bool(Value &, APInt &)> ExternalAnalysis) {
bool UsedExternalAnalysis = false;
auto AccumulateOffset = [&](APInt Index, uint64_t Size) -> bool {
Index = Index.sextOrTrunc(Offset.getBitWidth());
APInt IndexedSize = APInt(Offset.getBitWidth(), Size);
// For array or vector indices, scale the index by the size of the type.
if (!UsedExternalAnalysis) {
Offset += Index * IndexedSize;
} else {
// External Analysis can return a result higher/lower than the value
// represents. We need to detect overflow/underflow.
bool Overflow = false;
APInt OffsetPlus = Index.smul_ov(IndexedSize, Overflow);
if (Overflow)
return false;
Offset = Offset.sadd_ov(OffsetPlus, Overflow);
if (Overflow)
return false;
}
return true;
};
auto begin = generic_gep_type_iterator<decltype(Index.begin())>::begin(
SourceType, Index.begin());
auto end = generic_gep_type_iterator<decltype(Index.end())>::end(Index.end());
for (auto GTI = begin, GTE = end; GTI != GTE; ++GTI) {
// Scalable vectors are multiplied by a runtime constant.
bool ScalableType = false;
if (isa<ScalableVectorType>(GTI.getIndexedType()))
ScalableType = true;
Value *V = GTI.getOperand();
StructType *STy = GTI.getStructTypeOrNull();
// Handle ConstantInt if possible.
if (auto ConstOffset = dyn_cast<ConstantInt>(V)) {
if (ConstOffset->isZero())
continue;
// if the type is scalable and the constant is not zero (vscale * n * 0 =
// 0) bailout.
if (ScalableType)
return false;
// Handle a struct index, which adds its field offset to the pointer.
if (STy) {
unsigned ElementIdx = ConstOffset->getZExtValue();
const StructLayout *SL = DL.getStructLayout(STy);
// Element offset is in bytes.
if (!AccumulateOffset(
APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx)),
1))
return false;
continue;
}
if (!AccumulateOffset(ConstOffset->getValue(),
DL.getTypeAllocSize(GTI.getIndexedType())))
return false;
continue;
}
// The operand is not constant, check if an external analysis was provided.
// External analsis is not applicable to a struct type.
if (!ExternalAnalysis || STy || ScalableType)
return false;
APInt AnalysisIndex;
if (!ExternalAnalysis(*V, AnalysisIndex))
return false;
UsedExternalAnalysis = true;
if (!AccumulateOffset(AnalysisIndex,
DL.getTypeAllocSize(GTI.getIndexedType())))
return false;
}
return true;
}
bool GEPOperator::collectOffset(
const DataLayout &DL, unsigned BitWidth,
MapVector<Value *, APInt> &VariableOffsets,
APInt &ConstantOffset) const {
assert(BitWidth == DL.getIndexSizeInBits(getPointerAddressSpace()) &&
"The offset bit width does not match DL specification.");
auto CollectConstantOffset = [&](APInt Index, uint64_t Size) {
Index = Index.sextOrTrunc(BitWidth);
APInt IndexedSize = APInt(BitWidth, Size);
ConstantOffset += Index * IndexedSize;
};
for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
GTI != GTE; ++GTI) {
// Scalable vectors are multiplied by a runtime constant.
bool ScalableType = isa<ScalableVectorType>(GTI.getIndexedType());
Value *V = GTI.getOperand();
StructType *STy = GTI.getStructTypeOrNull();
// Handle ConstantInt if possible.
if (auto ConstOffset = dyn_cast<ConstantInt>(V)) {
if (ConstOffset->isZero())
continue;
// If the type is scalable and the constant is not zero (vscale * n * 0 =
// 0) bailout.
// TODO: If the runtime value is accessible at any point before DWARF
// emission, then we could potentially keep a forward reference to it
// in the debug value to be filled in later.
if (ScalableType)
return false;
// Handle a struct index, which adds its field offset to the pointer.
if (STy) {
unsigned ElementIdx = ConstOffset->getZExtValue();
const StructLayout *SL = DL.getStructLayout(STy);
// Element offset is in bytes.
CollectConstantOffset(APInt(BitWidth, SL->getElementOffset(ElementIdx)),
1);
continue;
}
CollectConstantOffset(ConstOffset->getValue(),
DL.getTypeAllocSize(GTI.getIndexedType()));
continue;
}
if (STy || ScalableType)
return false;
// Insert an initial offset of 0 for V iff none exists already, then
// increment the offset by IndexedSize.
VariableOffsets.insert({V, APInt(BitWidth, 0)});
APInt IndexedSize =
APInt(BitWidth, DL.getTypeAllocSize(GTI.getIndexedType()));
VariableOffsets[V] += IndexedSize;
}
return true;
}
} // namespace llvm
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