Move the capture analysis from MemoryDependencyAnalysis to a more general place
so that it can be reused in MemCpyOptimizer. This analysis is needed to remove
an unnecessary memcpy when returning a struct into a local variable.
rdar://11341081
PR12686
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156776 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index a87cce3..4341577 100644
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -662,7 +662,11 @@
// the use analysis, we also need to know that it does not sneakily
// access dest. We rely on AA to figure this out for us.
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- if (AA.getModRefInfo(C, cpyDest, srcSize) != AliasAnalysis::NoModRef)
+ AliasAnalysis::ModRefResult MR = AA.getModRefInfo(C, cpyDest, srcSize);
+ // If necessary, perform additional analysis.
+ if (MR != AliasAnalysis::NoModRef)
+ MR = AA.callCapturesBefore(C, cpyDest, srcSize, &DT);
+ if (MR != AliasAnalysis::NoModRef)
return false;
// All the checks have passed, so do the transformation.