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Handle one offset with growth case seen in povray. Namely, if we have an offset, 

and the offset lands at a field boundary in the old type, construct a new type,
copying the fields masked by the offset from the old type, and unify with that.

llvm-svn: 26775
This commit is contained in:
Andrew Lenharth 2006-03-15 04:04:21 +00:00
parent c254e5b180
commit 3196422df0
1 changed files with 42 additions and 13 deletions
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55
llvm/lib/Analysis/DataStructure/DataStructure.cpp
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@ -492,13 +492,51 @@ bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset,
return true;
}
if (Offset) { // We could handle this case, but we don't for now...
std::cerr << "UNIMP: Trying to merge a growth type into "
<< "offset != 0: Collapsing!\n";
if (FoldIfIncompatible) foldNodeCompletely();
// If this node would have to have an unreasonable number of fields, just
// collapse it. This can occur for fortran common blocks, which have stupid
// things like { [100000000 x double], [1000000 x double] }.
unsigned NumFields = (NewTySize+Offset+DS::PointerSize-1) >> DS::PointerShift;
if (NumFields > 256) {
foldNodeCompletely();
return true;
}
if (Offset) {
//handle some common cases:
// Ty: struct { t1, t2, t3, t4, ..., tn}
// NewTy: struct { offset, stuff...}
// try merge with NewTy: struct {t1, t2, stuff...} if offset lands exactly on a field in Ty
if (isa<StructType>(NewTy) && isa<StructType>(Ty)) {
DEBUG(std::cerr << "Ty: " << *Ty << "\nNewTy: " << *NewTy << "@" << Offset << "\n");
unsigned O = 0;
const StructType *STy = cast<StructType>(Ty);
const StructLayout &SL = *TD.getStructLayout(STy);
unsigned i = SL.getElementContainingOffset(Offset);
//Either we hit it exactly or give up
if (SL.MemberOffsets[i] != Offset) {
if (FoldIfIncompatible) foldNodeCompletely();
return true;
}
std::vector<const Type*> nt;
for (unsigned x = 0; x < i; ++x)
nt.push_back(STy->getElementType(x));
STy = cast<StructType>(NewTy);
nt.insert(nt.end(), STy->element_begin(), STy->element_end());
//and merge
STy = StructType::get(nt);
DEBUG(std::cerr << "Trying with: " << *STy << "\n");
return mergeTypeInfo(STy, 0);
}
std::cerr << "UNIMP: Trying to merge a growth type into "
<< "offset != 0: Collapsing!\n";
abort();
if (FoldIfIncompatible) foldNodeCompletely();
return true;
}
// Okay, the situation is nice and simple, we are trying to merge a type in
// at offset 0 that is bigger than our current type. Implement this by
// switching to the new type and then merge in the smaller one, which should
@ -506,15 +544,6 @@ bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset,
// ok, it will collapse the node as appropriate.
//
// If this node would have to have an unreasonable number of fields, just
// collapse it. This can occur for fortran common blocks, which have stupid
// things like { [100000000 x double], [1000000 x double] }.
unsigned NumFields = (NewTySize+DS::PointerSize-1) >> DS::PointerShift;
if (NumFields > 256) {
foldNodeCompletely();
return true;
}
const Type *OldTy = Ty;
Ty = NewTy;
NodeType &= ~Array;