When looking for dependencies on the src pointer, scan the src pointer. Scanning
on the memcpy call will pull up other unrelated stuff. Fixes PR11142.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142150 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index eeb8931..298d692 100644
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -806,21 +806,26 @@
// a) memcpy-memcpy xform which exposes redundance for DSE.
// b) call-memcpy xform for return slot optimization.
MemDepResult DepInfo = MD->getDependency(M);
- if (!DepInfo.isClobber())
- return false;
-
- if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(DepInfo.getInst()))
- return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue());
-
- if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
- if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
- CopySize->getZExtValue(), C)) {
- MD->removeInstruction(M);
- M->eraseFromParent();
- return true;
+ if (DepInfo.isClobber()) {
+ if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
+ if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
+ CopySize->getZExtValue(), C)) {
+ MD->removeInstruction(M);
+ M->eraseFromParent();
+ return true;
+ }
}
}
+ AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+ AliasAnalysis::Location SrcLoc = AA.getLocationForSource(M);
+ MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(SrcLoc, true,
+ M, M->getParent());
+ if (SrcDepInfo.isClobber()) {
+ if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(SrcDepInfo.getInst()))
+ return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue());
+ }
+
return false;
}