https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56961
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #8)
> (In reply to Richard Biener from comment #7)
> > I suggest
> >
> > Index: gcc/cp/cp-gimplify.c
> > ===================================================================
> > --- gcc/cp/cp-gimplify.c (revision 211262)
> > +++ gcc/cp/cp-gimplify.c (working copy)
> > @@ -630,18 +630,8 @@ cp_gimplify_expr (tree *expr_p, gimple_s
> > Also drop volatile variables on the RHS to avoid infinite
> > recursion from gimplify_expr trying to load the value. */
> > if (!TREE_SIDE_EFFECTS (op1)
> > - || (DECL_P (op1) && TREE_THIS_VOLATILE (op1)))
> > + || TREE_THIS_VOLATILE (op1))
> > *expr_p = op0;
> > - else if (TREE_CODE (op1) == MEM_REF
> > - && TREE_THIS_VOLATILE (op1))
> > - {
> > - /* Similarly for volatile MEM_REFs on the RHS. */
> > - if (!TREE_SIDE_EFFECTS (TREE_OPERAND (op1, 0)))
> > - *expr_p = op0;
> > - else
> > - *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
> > - TREE_OPERAND (op1, 0), op0);
> > - }
> > else
> > *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
> > op0, op1);
>
> This might of course drop arbitrary side-effects of op1 such as
> a volatile load from a.b[foo()] where foo () would be dropped.
>
> So it isn't really correct.
The following should preserve those.
Index: gcc/cp/cp-gimplify.c
===================================================================
--- gcc/cp/cp-gimplify.c (revision 211262)
+++ gcc/cp/cp-gimplify.c (working copy)
@@ -629,18 +629,14 @@ cp_gimplify_expr (tree *expr_p, gimple_s
Also drop volatile variables on the RHS to avoid infinite
recursion from gimplify_expr trying to load the value. */
- if (!TREE_SIDE_EFFECTS (op1)
- || (DECL_P (op1) && TREE_THIS_VOLATILE (op1)))
+ if (!TREE_SIDE_EFFECTS (op1))
*expr_p = op0;
- else if (TREE_CODE (op1) == MEM_REF
- && TREE_THIS_VOLATILE (op1))
+ else if (TREE_THIS_VOLATILE (op1)
+ && (REFERENCE_CLASS_P (op1) || DECL_P (op1)))
{
- /* Similarly for volatile MEM_REFs on the RHS. */
- if (!TREE_SIDE_EFFECTS (TREE_OPERAND (op1, 0)))
- *expr_p = op0;
- else
- *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
- TREE_OPERAND (op1, 0), op0);
+ *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
+ op0, build_fold_addr_expr (op1));
+
}
else
*expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
