If we're changing the source of a memcpy we need to use the alignment
of the source, not the original alignment since it may no longer
be valid.
Fixes rdar://8400094
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114781 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 24fae42..f94c9e2 100644
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -697,14 +697,16 @@
M->getParent()->getParent()->getParent(),
M->getIntrinsicID(), ArgTys, 3);
+ // Make sure to use the alignment of the source since we're changing the
+ // location we're reading from.
+ // TODO: Is this worth it if we're creating a less aligned memcpy? For
+ // example we could be moving from movaps -> movq on x86.
Value *Args[5] = {
M->getRawDest(), MDep->getRawSource(), M->getLength(),
- M->getAlignmentCst(), M->getVolatileCst()
+ MDep->getAlignmentCst(), M->getVolatileCst()
};
-
CallInst *C = CallInst::Create(MemCpyFun, Args, Args+5, "", M);
-
// If C and M don't interfere, then this is a valid transformation. If they
// did, this would mean that the two sources overlap, which would be bad.
if (MD.getDependency(C) == dep) {