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//===- TransformInternals.cpp - Implement shared functions for transforms -===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines shared functions used by the different components of the
// Transforms library.
//
//===----------------------------------------------------------------------===//
#include "TransformInternals.h"
#include "llvm/Type.h"
#include "llvm/Analysis/Expressions.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
using namespace llvm;
static const Type *getStructOffsetStep(const StructType *STy, uint64_t &Offset,
std::vector<Value*> &Indices,
const TargetData &TD) {
assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!");
const StructLayout *SL = TD.getStructLayout(STy);
// This loop terminates always on a 0 <= i < MemberOffsets.size()
unsigned i;
for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
break;
assert(Offset >= SL->MemberOffsets[i] &&
(i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
// Make sure to save the current index...
Indices.push_back(ConstantUInt::get(Type::UIntTy, i));
Offset = SL->MemberOffsets[i];
return STy->getContainedType(i);
}
// getStructOffsetType - Return a vector of offsets that are to be used to index
// into the specified struct type to get as close as possible to index as we
// can. Note that it is possible that we cannot get exactly to Offset, in which
// case we update offset to be the offset we actually obtained. The resultant
// leaf type is returned.
//
// If StopEarly is set to true (the default), the first object with the
// specified type is returned, even if it is a struct type itself. In this
// case, this routine will not drill down to the leaf type. Set StopEarly to
// false if you want a leaf
//
const Type *llvm::getStructOffsetType(const Type *Ty, unsigned &Offset,
std::vector<Value*> &Indices,
const TargetData &TD, bool StopEarly) {
if (Offset == 0 && StopEarly && !Indices.empty())
return Ty; // Return the leaf type
uint64_t ThisOffset;
const Type *NextType;
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
if (STy->getNumElements()) {
Offset = 0;
return STy;
}
ThisOffset = Offset;
NextType = getStructOffsetStep(STy, ThisOffset, Indices, TD);
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
assert(Offset == 0 || Offset < TD.getTypeSize(ATy) &&
"Offset not in composite!");
NextType = ATy->getElementType();
unsigned ChildSize = TD.getTypeSize(NextType);
if (ConstantSInt::isValueValidForType(Type::IntTy, Offset/ChildSize))
Indices.push_back(ConstantSInt::get(Type::IntTy, Offset/ChildSize));
else
Indices.push_back(ConstantSInt::get(Type::LongTy, Offset/ChildSize));
ThisOffset = (Offset/ChildSize)*ChildSize;
} else {
Offset = 0; // Return the offset that we were able to achieve
return Ty; // Return the leaf type
}
unsigned SubOffs = Offset - ThisOffset;
const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
Indices, TD, StopEarly);
Offset = ThisOffset + SubOffs;
return LeafTy;
}
// ConvertibleToGEP - This function returns true if the specified value V is
// a valid index into a pointer of type Ty. If it is valid, Idx is filled in
// with the values that would be appropriate to make this a getelementptr
// instruction. The type returned is the root type that the GEP would point to
//
const Type *llvm::ConvertibleToGEP(const Type *Ty, Value *OffsetVal,
std::vector<Value*> &Indices,
const TargetData &TD,
BasicBlock::iterator *BI) {
return 0;
}
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