Add handling of !invariant.load to PropagateMetadata.

Summary:
This will let e.g. the load/store vectorizer propagate this metadata
appropriately.

Reviewers: arsenm

Subscribers: tra, jholewinski, hfinkel, mzolotukhin

Differential Revision: https://reviews.llvm.org/D23479

llvm-svn: 281153
diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index 53e7153..5a51fd8 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -454,9 +454,10 @@
   SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
   I0->getAllMetadataOtherThanDebugLoc(Metadata);
 
-  for (auto Kind : { LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
-                     LLVMContext::MD_noalias, LLVMContext::MD_fpmath,
-                     LLVMContext::MD_nontemporal }) {
+  for (auto Kind :
+       {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
+        LLVMContext::MD_noalias, LLVMContext::MD_fpmath,
+        LLVMContext::MD_nontemporal, LLVMContext::MD_invariant_load}) {
     MDNode *MD = I0->getMetadata(Kind);
 
     for (int J = 1, E = VL.size(); MD && J != E; ++J) {
@@ -469,13 +470,12 @@
       case LLVMContext::MD_alias_scope:
         MD = MDNode::getMostGenericAliasScope(MD, IMD);
         break;
-      case LLVMContext::MD_noalias:
-        MD = MDNode::intersect(MD, IMD);
-        break;
       case LLVMContext::MD_fpmath:
         MD = MDNode::getMostGenericFPMath(MD, IMD);
         break;
+      case LLVMContext::MD_noalias:
       case LLVMContext::MD_nontemporal:
+      case LLVMContext::MD_invariant_load:
         MD = MDNode::intersect(MD, IMD);
         break;
       default: