3 files changed, 19 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 43ccb995958..7135874003d 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1791,6 +1791,19 @@ static void patchReplacementInstruction(Instruction *I, Value *Repl) {
       case LLVMContext::MD_tbaa:
         ReplInst->setMetadata(Kind, MDNode::getMostGenericTBAA(IMD, ReplMD));
         break;
+      case LLVMContext::MD_alias_scope:
+      case LLVMContext::MD_noalias:
+        // FIXME: If both the original and replacement value are part of the
+        // same control-flow region (meaning that the execution of one
+        // guarentees the executation of the other), then we can combine the
+        // noalias scopes here and do better than the general conservative
+        // answer.
+
+        // In general, GVN unifies expressions over different control-flow
+        // regions, and so we need a conservative combination of the noalias
+        // scopes.
+        ReplInst->setMetadata(Kind, MDNode::intersect(IMD, ReplMD));
+        break;
       case LLVMContext::MD_range:
         ReplInst->setMetadata(Kind, MDNode::getMostGenericRange(IMD, ReplMD));
         break;
diff --git a/llvm/lib/Transforms/Scalar/Scalar.cpp b/llvm/lib/Transforms/Scalar/Scalar.cpp
index de724d419a4..12df676df87 100644
--- a/llvm/lib/Transforms/Scalar/Scalar.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalar.cpp
@@ -203,6 +203,10 @@ void LLVMAddTypeBasedAliasAnalysisPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createTypeBasedAliasAnalysisPass());
 }
 
+void LLVMAddScopedNoAliasAAPass(LLVMPassManagerRef PM) {
+  unwrap(PM)->add(createScopedNoAliasAAPass());
+}
+
 void LLVMAddBasicAliasAnalysisPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createBasicAliasAnalysisPass());
 }
diff --git a/llvm/lib/Transforms/Scalar/Scalarizer.cpp b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
index 7a73f113b1d..813041ab255 100644
--- a/llvm/lib/Transforms/Scalar/Scalarizer.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
@@ -312,6 +312,8 @@ bool Scalarizer::canTransferMetadata(unsigned Tag) {
           || Tag == LLVMContext::MD_fpmath
           || Tag == LLVMContext::MD_tbaa_struct
           || Tag == LLVMContext::MD_invariant_load
+          || Tag == LLVMContext::MD_alias_scope
+          || Tag == LLVMContext::MD_noalias
           || Tag == ParallelLoopAccessMDKind);
 }