Teach alias analysis about readnone/readonly functions.
Based on a patch by Török Edwin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44279 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index cbbc530..c6e34da 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -952,6 +952,12 @@
if (Ptr != OnlyReadsMemoryTable->end() && strcmp(*Ptr, NamePtr) == 0)
return OnlyReadsMemory;
+ const ParamAttrsList *Attrs = F->getFunctionType()->getParamAttrs();
+ if (Attrs && Attrs->paramHasAttr(0, ParamAttr::ReadNone))
+ return DoesNotAccessMemory;
+ if (Attrs && Attrs->paramHasAttr(0, ParamAttr::ReadOnly))
+ return OnlyReadsMemory;
+
return UnknownModRefBehavior;
}