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Don't commit stores with addresses that have indices that are not 

compile-time constant integers or that are out of bounds for their
corresponding static array types. These can cause aliasing that
GlobalOpt assumes won't happen.

llvm-svn: 81165
This commit is contained in:
Dan Gohman 2009-09-07 22:44:55 +00:00
parent 82e747580f
commit 161429fe7e
1 changed files with 21 additions and 0 deletions
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21
llvm/lib/Transforms/IPO/GlobalOpt.cpp
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@ -2044,6 +2044,27 @@ static bool isSimpleEnoughPointerToCommit(Constant *C, LLVMContext &Context) {
// external globals.
if (!GV->hasDefinitiveInitializer())
return false;
gep_type_iterator GEPI = gep_type_begin(CE), E = gep_type_end(CE);
User::op_iterator OI = next(CE->op_begin());
// The first index must be zero.
ConstantInt *CI = dyn_cast<ConstantInt>(*OI);
if (!CI || !CI->isZero()) return false;
++GEPI;
++OI;
// The remaining indices must be compile-time known integers within the
// bounds of the corresponding static array types.
for (; GEPI != E; ++GEPI, ++OI) {
CI = dyn_cast<ConstantInt>(*OI);
if (!CI) return false;
if (const ArrayType *ATy = dyn_cast<ArrayType>(*GEPI))
if (CI->getValue().getActiveBits() > 64 ||
CI->getZExtValue() >= ATy->getNumElements())
return false;
}
return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE,
Context);
}