commit a5efa7386ad9920e969ba4f155de3b40f8118cae
author John McCall <rjmccall@apple.com> Thu Aug 25 23:04:34 2011 +0000
committer John McCall <rjmccall@apple.com> Thu Aug 25 23:04:34 2011 +0000
tree cfa90d732233b92aab897950fdd571c28cf9dbaa
parent 5cc730cdef97d98df0b33a21a6b9568b9cddccb1

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.

llvm-svn: 138599

clang/lib/CodeGen/CGClass.cpp

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 8e46fcd..8bdfbf1 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -401,7 +401,8 @@
   AggValueSlot AggSlot =
     AggValueSlot::forAddr(V, Qualifiers(),
                           AggValueSlot::IsDestructed,
-                          AggValueSlot::DoesNotNeedGCBarriers);
+                          AggValueSlot::DoesNotNeedGCBarriers,
+                          AggValueSlot::IsNotAliased);
 
   CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
   
@@ -441,7 +442,8 @@
       AggValueSlot Slot =
         AggValueSlot::forAddr(Dest, LHS.getQuals(),
                               AggValueSlot::IsDestructed,
-                              AggValueSlot::DoesNotNeedGCBarriers);
+                              AggValueSlot::DoesNotNeedGCBarriers,
+                              AggValueSlot::IsNotAliased);
       
       CGF.EmitAggExpr(MemberInit->getInit(), Slot);
     }
@@ -1330,7 +1332,8 @@
   AggValueSlot AggSlot =
     AggValueSlot::forAddr(ThisPtr, Qualifiers(),
                           AggValueSlot::IsDestructed,
-                          AggValueSlot::DoesNotNeedGCBarriers);
+                          AggValueSlot::DoesNotNeedGCBarriers,
+                          AggValueSlot::IsNotAliased);
 
   EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);