Fix a memcpy lowering bug. Even though the memcpy alignment is smaller than the desired alignment, the frame destination alignment may still be larger than the desired alignment. Don't change its alignment to something smaller.

llvm-svn: 51970

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index a9b7381a096..8d0d344d62b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2633,8 +2633,9 @@ bool MeetsMaxMemopRequirement(std::vector<MVT::ValueType> &MemOps,
           if (AllowUnalign)
             VT = MVT::iAny;
         } else {
-          // Give the stack frame object a larger alignment.
-          MFI->setObjectAlignment(FI, NewAlign);
+          // Give the stack frame object a larger alignment if needed.
+          if (MFI->getObjectAlignment(FI) < NewAlign)
+            MFI->setObjectAlignment(FI, NewAlign);
           Align = NewAlign;
         }
       }