When we can't prove that the target of an aggregate copy is
a complete object, the memcpy needs to use the data size of
the structure instead of its sizeof() value.  Fixes PR12204.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153613 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 4455f1a..f5d7944 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -1875,7 +1875,8 @@
           if (Align > AI->getAlignment())
             AI->setAlignment(Align);
           Args.push_back(AI);
-          EmitAggregateCopy(AI, Addr, I->Ty, RV.isVolatileQualified());
+          EmitAggregateCopy(AI, Addr, I->Ty, RV.isVolatileQualified(),
+                            /*destIsCompleteObject*/ true);
               
           // Validate argument match.
           checkArgMatches(AI, IRArgNo, IRFuncTy);