[SimplifyCFG] Preserve !llvm.mem.parallel_loop_access when merging

When SimplifyCFG merges identical instructions from both sides of a diamond, it
can preserve !llvm.mem.parallel_loop_access (as it does with most of the other
metadata). There's no real data or control dependency change in this case.

llvm-svn: 267515

2 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 75eda97d0a3..82961a678be 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1539,6 +1539,7 @@ void llvm::combineMetadata(Instruction *K, const Instruction *J,
         K->setMetadata(Kind, MDNode::getMostGenericAliasScope(JMD, KMD));
         break;
       case LLVMContext::MD_noalias:
+      case LLVMContext::MD_mem_parallel_loop_access:
         K->setMetadata(Kind, MDNode::intersect(JMD, KMD));
         break;
       case LLVMContext::MD_range:
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 23199b37b29..4239764ebc7 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1143,7 +1143,8 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
         LLVMContext::MD_fpmath,  LLVMContext::MD_invariant_load,
         LLVMContext::MD_nonnull, LLVMContext::MD_invariant_group,
         LLVMContext::MD_align,   LLVMContext::MD_dereferenceable,
-        LLVMContext::MD_dereferenceable_or_null};
+        LLVMContext::MD_dereferenceable_or_null,
+        LLVMContext::MD_mem_parallel_loop_access};
     combineMetadata(I1, I2, KnownIDs);
     I2->eraseFromParent();
     Changed = true;