patch for PR9027 and // rdar://11861085
Title: [PR9027] volatile struct bug: member is not loaded at -O;
This is caused by last flag passed to @llvm.memcpy being false,
not honoring that aggregate has at least one 'volatile' data member
(even though aggregate itself has not been qualified as 'volatile'.
As a result, optimization optimizes away the memcpy altogether.
Patch review by John MaCall (I still need to fix up a test though).
llvm-svn: 173535
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a35ef0c..8c64e8a6 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -792,6 +792,11 @@
AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
needsGC(E->getLHS()->getType()),
AggValueSlot::IsAliased);
+ // A non-volatile aggregate destination might have volatile member.
+ if (!LHSSlot.isVolatile() &&
+ CGF.hasVolatileMember(E->getLHS()->getType()))
+ LHSSlot.setVolatile(true);
+
CGF.EmitAggExpr(E->getRHS(), LHSSlot);
// Copy into the destination if the assignment isn't ignored.