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Make ConvertableToGEP handle cases where the user is indexing into the

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first element of a structure type.  Before this would not be handled because
getStructOffset would either stop immediately (because StopEarly was true
and Offset = 0), or blast past the level we wanted.

Now ConvertableToGEP steps down through the type one level at a time, checking
the Offset and Scale conditions at each step


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1931 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2002-03-21 06:27:20 +00:00
parent 8e86542fb6
commit 9e77f7e08b
1 changed files with 29 additions and 23 deletions
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52
lib/Transforms/TransformInternals.cpp
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@ -83,6 +83,27 @@ BasicBlock::iterator InsertInstBeforeInst(Instruction *NewInst,
static const Type *getStructOffsetStep(const StructType *STy, unsigned &Offset,
std::vector<Value*> &Indices) {
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::UByteTy, 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
@ -95,36 +116,22 @@ BasicBlock::iterator InsertInstBeforeInst(Instruction *NewInst,
// false if you want a leaf
//
const Type *getStructOffsetType(const Type *Ty, unsigned &Offset,
std::vector<Value*> &Offsets,
std::vector<Value*> &Indices,
bool StopEarly = true) {
if (Offset == 0 && StopEarly && !Offsets.empty())
if (Offset == 0 && StopEarly && !Indices.empty())
return Ty; // Return the leaf type
unsigned ThisOffset;
const Type *NextType;
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
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...
Offsets.push_back(ConstantUInt::get(Type::UByteTy, i));
ThisOffset = SL->MemberOffsets[i];
NextType = STy->getElementTypes()[i];
ThisOffset = Offset;
NextType = getStructOffsetStep(STy, ThisOffset, Indices);
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
assert(Offset < TD.getTypeSize(ATy) && "Offset not in composite!");
NextType = ATy->getElementType();
unsigned ChildSize = TD.getTypeSize(NextType);
Offsets.push_back(ConstantUInt::get(Type::UIntTy, Offset/ChildSize));
Indices.push_back(ConstantUInt::get(Type::UIntTy, Offset/ChildSize));
ThisOffset = (Offset/ChildSize)*ChildSize;
} else {
Offset = 0; // Return the offset that we were able to acheive
@ -133,7 +140,7 @@ const Type *getStructOffsetType(const Type *Ty, unsigned &Offset,
unsigned SubOffs = Offset - ThisOffset;
const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
Offsets, StopEarly);
Indices, StopEarly);
Offset = ThisOffset + SubOffs;
return LeafTy;
}
@ -183,10 +190,9 @@ const Type *ConvertableToGEP(const Type *Ty, Value *OffsetVal,
CompTy = cast<CompositeType>(NextTy);
if (const StructType *StructTy = dyn_cast<StructType>(CompTy)) {
// Step into the appropriate element of the structure...
unsigned ActualOffset = Offset;
NextTy = getStructOffsetType(StructTy, ActualOffset, Indices);
if (StructTy == NextTy && ActualOffset == 0)
return 0; // No progress. :(
NextTy = getStructOffsetStep(StructTy, ActualOffset, Indices);
Offset -= ActualOffset;
} else {
const Type *ElTy = cast<SequentialType>(CompTy)->getElementType();