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Teach FunctionAttrs about AccessesArgumentsReadonly.

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llvm-svn: 118617
This commit is contained in:
Dan Gohman 2010-11-09 19:56:27 +00:00
parent 0f262ff853
commit 4cba066d9f
1 changed files with 19 additions and 0 deletions
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19
lib/Transforms/IPO/FunctionAttrs.cpp
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@ -152,6 +152,25 @@ bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
}
// Only reads and writes local memory.
continue;
case AliasAnalysis::AccessesArgumentsReadonly:
// Check whether all pointer arguments point to local memory, and
// ignore calls that only access local memory.
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI) {
Value *Arg = *CI;
if (Arg->getType()->isPointerTy()) {
AliasAnalysis::Location Loc(Arg,
AliasAnalysis::UnknownSize,
I->getMetadata(LLVMContext::MD_tbaa));
if (!AA->pointsToConstantMemory(Loc, /*OrLocal=*/true)) {
// Reads non-local memory.
ReadsMemory = true;
break;
}
}
}
// Only reads memory.
continue;
default:
// Otherwise, be conservative.
break;