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Improve the safety of my globalopt enhancement by ensuring that the bitcast

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of the stored value to the new store type is always.  Also, add a testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123563 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
2011-01-16 04:33:33 +00:00
parent 156eb0a569
commit 66f708f7e5
2 changed files with 81 additions and 12 deletions
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34
lib/Transforms/IPO/GlobalOpt.cpp
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@ -2358,21 +2358,31 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal,
const Type *NewTy=cast<PointerType>(Ptr->getType())->getElementType();
// A bitcast'd pointer implicitly points to the first field of a
// struct. Insert implicity "gep @x, 0, 0, ..." until we get down
// to the first concrete member.
// FIXME: This could be extended to work for arrays as well.
while (const StructType *STy = dyn_cast<StructType>(NewTy)) {
NewTy = STy->getTypeAtIndex(0U);
// In order to push the bitcast onto the stored value, a bitcast
// from NewTy to Val's type must be legal. If it's not, we can try
// introspecting NewTy to find a legal conversion.
while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) {
// If NewTy is a struct, we can convert the pointer to the struct
// into a pointer to its first member.
// FIXME: This could be extended to support arrays as well.
if (const StructType *STy = dyn_cast<StructType>(NewTy)) {
NewTy = STy->getTypeAtIndex(0U);
const IntegerType *IdxTy =IntegerType::get(NewTy->getContext(), 32);
Constant *IdxZero = ConstantInt::get(IdxTy, 0, false);
Constant * const IdxList[] = {IdxZero, IdxZero};
Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList, 2);
const IntegerType *IdxTy =IntegerType::get(NewTy->getContext(), 32);
Constant *IdxZero = ConstantInt::get(IdxTy, 0, false);
Constant * const IdxList[] = {IdxZero, IdxZero};
Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList, 2);
// If we can't improve the situation by introspecting NewTy,
// we have to give up.
} else {
return 0;
}
}
if (!isa<PointerType>(NewTy)) return false;
// If we found compatible types, go ahead and push the bitcast
// onto the stored value.
Val = ConstantExpr::getBitCast(Val, NewTy);
}