GVN: Preserve invariant.load metadata

If both instructions to be replaced are marked invariant the resulting
instruction is invariant.

rdar://13358910

Fix by Erik Eckstein!

llvm-svn: 211801

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 56781d44aaa..106eba099ca 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1798,6 +1798,10 @@ static void patchReplacementInstruction(Instruction *I, Value *Repl) {
       case LLVMContext::MD_fpmath:
         ReplInst->setMetadata(Kind, MDNode::getMostGenericFPMath(IMD, ReplMD));
         break;
+      case LLVMContext::MD_invariant_load:
+        // Only set the !invariant.load if it is present in both instructions.
+        ReplInst->setMetadata(Kind, IMD);
+        break;
       }
     }
   }