Track whether an AggValueSlot is potentially aliased, and do not

emit call results into potentially aliased slots.  This allows us
to properly mark indirect return slots as noalias, at the cost
of requiring an extra memcpy when assigning an aggregate call
result into a l-value.  It also brings us into compliance with
the x86-64 ABI.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@138599 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index b7b127fc50..461a173f53 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -786,7 +786,8 @@ void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
   } else {
     EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue, Qualifiers(),
                                           AggValueSlot::IsDestructed,
-                                          AggValueSlot::DoesNotNeedGCBarriers));
+                                          AggValueSlot::DoesNotNeedGCBarriers,
+                                          AggValueSlot::IsNotAliased));
   }
 
   EmitBranchThroughCleanup(ReturnBlock);