On Tue, Mar 14, 2017 at 1:04 AM, Bill Schmidt
<wschm...@linux.vnet.ibm.com> wrote:
> Hi,
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79908 shows a case where
> pass_stdarg ICEs attempting to gimplify a COMPLEX_EXPR with side
> effects as an lvalue. The expression is not addressable, so the
> gimplification fails. This patch says, hey, don't do that!
>
> The resulting GIMPLE looks fine afterward. Bootstrapped and tested
> on powerpc64le-unknown-linux-gnu with no regressions. Is this ok
> for trunk?
>
> Thanks,
> Bill
>
>
> [gcc]
>
> 2017-03-13 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>
> PR tree-optimization/79908
> * tree-stdarg.c (expand_ifn_va_arg_1): Don't force something to be
> an lvalue that isn't addressable.
>
> [gcc/testsuite]
>
> 2017-03-13 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>
> PR tree-optimization/79908
> * gcc.dg/torture/pr79908.c: New file.
>
>
> Index: gcc/testsuite/gcc.dg/torture/pr79908.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/torture/pr79908.c (nonexistent)
> +++ gcc/testsuite/gcc.dg/torture/pr79908.c (working copy)
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +
> +/* Used to fail in the stdarg pass before fix for PR79908. */
> +
> +typedef __builtin_va_list __gnuc_va_list;
> +typedef __gnuc_va_list va_list;
> +
> +void testva (int n, ...)
> +{
> + va_list ap;
> + _Complex int i = __builtin_va_arg (ap, _Complex int);
> +}
> Index: gcc/tree-stdarg.c
> ===================================================================
> --- gcc/tree-stdarg.c (revision 246109)
> +++ gcc/tree-stdarg.c (working copy)
> @@ -1057,7 +1057,7 @@ expand_ifn_va_arg_1 (function *fun)
> types. */
> gimplify_assign (lhs, expr, &pre);
> }
> - else
> + else if (is_gimple_addressable (expr))
> gimplify_expr (&expr, &pre, &post, is_gimple_lvalue, fb_lvalue);
This is wrong - we lose side-effects this way and the only reason we gimplify
is to _not_ lose them.
Better is sth like
Index: gcc/tree-stdarg.c
===================================================================
--- gcc/tree-stdarg.c (revision 246082)
+++ gcc/tree-stdarg.c (working copy)
@@ -1058,7 +1058,7 @@ expand_ifn_va_arg_1 (function *fun)
gimplify_assign (lhs, expr, &pre);
}
else
- gimplify_expr (&expr, &pre, &post, is_gimple_lvalue, fb_lvalue);
+ gimplify_expr (&expr, &pre, &post, is_gimple_val, fb_either);
input_location = saved_location;
pop_gimplify_context (NULL);
>
> input_location = saved_location;
>
