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Fix bugs that Chris noticed in my last patch.

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llvm-svn: 47252
This commit is contained in:
Owen Anderson 2008-02-18 02:31:23 +00:00
parent 0b6ec4a6b2
commit 0ef73a5d06
1 changed files with 17 additions and 9 deletions
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26
lib/Analysis/BasicAliasAnalysis.cpp
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@ -250,22 +250,30 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
const Value *Object = getUnderlyingObject(P);
// Allocations and byval arguments are "new" objects.
if (Object &&
(isa<AllocationInst>(Object) ||
(isa<Argument>(Object) &&
(cast<Argument>(Object)->hasByValAttr() ||
cast<Argument>(Object)->hasNoAliasAttr())))) {
(isa<AllocationInst>(Object) || isa<Argument>(Object))) {
// Okay, the pointer is to a stack allocated (or effectively so, for
// for noalias parameters) object. If we can prove that
// the pointer never "escapes", then we know the call cannot clobber it,
// because it simply can't get its address.
if (!AddressMightEscape(Object))
return NoModRef;
if (isa<AllocationInst>(Object) ||
cast<Argument>(Object)->hasByValAttr() ||
cast<Argument>(Object)->hasNoAliasAttr())
if (!AddressMightEscape(Object)) {
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI)
if (getUnderlyingObject(CI->get()) == P)
return AliasAnalysis::getModRefInfo(CS, P, Size);
return NoModRef;
}
// If this is a tail call and P points to a stack location, we know that
// the tail call cannot access or modify the local stack.
if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
if (CI->isTailCall() && !isa<MallocInst>(Object))
return NoModRef;
if (isa<AllocationInst>(Object) ||
cast<Argument>(Object)->hasByValAttr())
if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
if (CI->isTailCall() && !isa<MallocInst>(Object))
return NoModRef;
}
}