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If a function only reads memory, then we know that...

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it only reads memory!  The other change has no
functional effect, it just seems more logical to
go in order of decreasing knowledge.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64463 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2009-02-13 17:32:26 +00:00
parent 02b6a6a75f
commit ddd8c450ec
1 changed files with 11 additions and 7 deletions
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18
lib/Analysis/AliasAnalysis.cpp
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@ -120,9 +120,13 @@ AliasAnalysis::getModRefBehavior(CallSite CS,
AliasAnalysis::ModRefBehavior
AliasAnalysis::getModRefBehavior(Function *F,
std::vector<PointerAccessInfo> *Info) {
if (F && F->doesNotAccessMemory())
// Can't do better than this.
return DoesNotAccessMemory;
if (F) {
if (F->doesNotAccessMemory())
// Can't do better than this.
return DoesNotAccessMemory;
else if (F->onlyReadsMemory())
return OnlyReadsMemory;
}
return UnknownModRefBehavior;
}
@ -130,10 +134,10 @@ AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
ModRefResult Mask = ModRef;
ModRefBehavior MRB = getModRefBehavior(CS);
if (MRB == OnlyReadsMemory)
Mask = Ref;
else if (MRB == DoesNotAccessMemory)
if (MRB == DoesNotAccessMemory)
return NoModRef;
else if (MRB == OnlyReadsMemory)
Mask = Ref;
else if (MRB == AliasAnalysis::AccessesArguments) {
bool doesAlias = false;
for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
@ -142,7 +146,7 @@ AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
doesAlias = true;
break;
}
if (!doesAlias)
return NoModRef;
}