When emitting a compound literal of POD type, continue to emit a
separate aggregate temporary and then memcpy it over to the
destination. This fixes a regression I introduced with r133235, where
the compound literal on the RHS of an assignment makes use of the
structure on the LHS of the assignment.
I'm deeply suspicious of AggExprEmitter::VisitBinAssign()'s
optimization where it emits the RHS of an aggregate assignment
directly into the LHS lvalue without checking whether there is any
aliasing between the LHS/RHS. However, I'm not in a position to
revisit this now.
Big thanks to Eli for finding the regression!
llvm-svn: 133261
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 6943169..b1ac731 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -247,6 +247,16 @@
void
AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
+ if (E->getType().isPODType(CGF.getContext())) {
+ // For a POD type, just emit a load of the lvalue + a copy, because our
+ // compound literal might alias the destination.
+ // FIXME: This is a band-aid; the real problem appears to be in our handling
+ // of assignments, where we store directly into the LHS without checking
+ // whether anything in the RHS aliases.
+ EmitAggLoadOfLValue(E);
+ return;
+ }
+
AggValueSlot Slot = EnsureSlot(E->getType());
CGF.EmitAggExpr(E->getInitializer(), Slot);
}