Expression statements undergo lvalue-to-rvalue conversion in C,
but not in C++, so don't emit aggregate loads of volatile references
in null context in C++. Happens to have been caught by an assertion.
We do not get the scalar case right. Volatiles are really broken.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112019 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprAgg.cpp b/lib/CodeGen/CGExprAgg.cpp
index 1b6254f..89fea39 100644
--- a/lib/CodeGen/CGExprAgg.cpp
+++ b/lib/CodeGen/CGExprAgg.cpp
@@ -192,10 +192,18 @@
void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
assert(Src.isAggregate() && "value must be aggregate value!");
- // If the result is ignored, don't copy from the value.
+ // If DestPtr is null, then we're evaluating an aggregate expression
+ // in a context (like an expression statement) that doesn't care
+ // about the result. C says that an lvalue-to-rvalue conversion is
+ // performed in these cases; C++ says that it is not. In either
+ // case, we don't actually need to do anything unless the value is
+ // volatile.
if (DestPtr == 0) {
- if (!Src.isVolatileQualified() || (IgnoreResult && Ignore))
+ if (!Src.isVolatileQualified() ||
+ CGF.CGM.getLangOptions().CPlusPlus ||
+ (IgnoreResult && Ignore))
return;
+
// If the source is volatile, we must read from it; to do that, we need
// some place to put it.
DestPtr = CGF.CreateMemTemp(E->getType(), "agg.tmp");