simplify this function a bit, allow DS-AA to build on/improve the mod/ref
results returned by AA, not just use one or the other.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20662 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/DataStructure/DataStructureAA.cpp b/lib/Analysis/DataStructure/DataStructureAA.cpp
index 74fdb1f..2d62162 100644
--- a/lib/Analysis/DataStructure/DataStructureAA.cpp
+++ b/lib/Analysis/DataStructure/DataStructureAA.cpp
@@ -173,9 +173,11 @@
///
AliasAnalysis::ModRefResult
DSAA::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
+ AliasAnalysis::ModRefResult Result =AliasAnalysis::getModRefInfo(CS, P, Size);
Function *F = CS.getCalledFunction();
- if (!F || F->isExternal())
- return AliasAnalysis::getModRefInfo(CS, P, Size);
+
+ if (!F || F->isExternal() || Result == NoModRef)
+ return Result;
// Clone the function TD graph, clearing off Mod/Ref flags
const Function *csParent = CS.getInstruction()->getParent()->getParent();
@@ -189,12 +191,13 @@
// Report the flags that have been added
const DSNodeHandle &DSH = TDGraph.getNodeForValue(P);
- if (const DSNode *N = DSH.getNode())
- if (N->isModified())
- return N->isRead() ? ModRef : Mod;
- else
- return N->isRead() ? Ref : NoModRef;
- return NoModRef;
+ if (const DSNode *N = DSH.getNode()) {
+ if (!N->isModified()) // We proved it was not modified.
+ Result = ModRefResult(Result & ~Mod);
+ if (!N->isRead()) // We proved it was not read.
+ Result = ModRefResult(Result & ~Ref);
+ }
+ return Result;
}