On Fri, 9 Jan 2015, Jakub Jelinek wrote:
> On Fri, Jan 09, 2015 at 11:59:44AM +0100, Richard Biener wrote:
> > > If you want, I can try instead of disabling it for tablejumps
> > > just move the label.
> >
> > Yeah, I'd prefer that - it can't be too difficult, no?
>
> So like this (tested just on the testcase, fully bootstrap/regtest
> will follow)?
Yeah.
> > > Still, I think we should be able to optimize it somewhere else too
> > > (we can remove the tablejumps not just if all jump_table_data
> > > entries point to next_bb, but even when they point to some
> > > completely different bb, as long as it is a single_succ_p). And
> > > ideally also optimize it at GIMPLE, but guess that is GCC 6
> > > material.
> >
> > cfgcleanup material, similar for GIMPLE I guess.
>
> You mean that cfgcleanup changes are GCC 6 material too?
Well, you have until the end of next week ;) For GIMPLE this is
a switch with all cases going to the same basic-block, right?
I think we optimize that in cleanup_control_expr_graph via the
single_succ_p case?
Thanks,
Richard.
> 2015-01-09 Jakub Jelinek <ja...@redhat.com>
>
> PR rtl-optimization/64536
> * cfgrtl.c (rtl_tidy_fallthru_edge): Handle removal of degenerate
> tablejumps.
>
> * gcc.dg/pr64536.c: New test.
>
> --- gcc/cfgrtl.c.jj 2015-01-08 18:10:23.616598916 +0100
> +++ gcc/cfgrtl.c 2015-01-09 14:47:26.637855477 +0100
> @@ -1791,6 +1791,24 @@ rtl_tidy_fallthru_edge (edge e)
> && (any_uncondjump_p (q)
> || single_succ_p (b)))
> {
> + rtx label;
> + rtx_jump_table_data *table;
> +
> + if (tablejump_p (q, &label, &table))
> + {
> + /* The label is likely mentioned in some instruction before
> + the tablejump and might not be DCEd, so turn it into
> + a note instead and move before the tablejump that is going to
> + be deleted. */
> + const char *name = LABEL_NAME (label);
> + PUT_CODE (label, NOTE);
> + NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
> + NOTE_DELETED_LABEL_NAME (label) = name;
> + rtx_insn *lab = safe_as_a <rtx_insn *> (label);
> + reorder_insns (lab, lab, PREV_INSN (q));
> + delete_insn (table);
> + }
> +
> #ifdef HAVE_cc0
> /* If this was a conditional jump, we need to also delete
> the insn that set cc0. */
> --- gcc/testsuite/gcc.dg/pr64536.c.jj 2015-01-09 13:55:53.035267213 +0100
> +++ gcc/testsuite/gcc.dg/pr64536.c 2015-01-09 13:55:53.035267213 +0100
> @@ -0,0 +1,67 @@
> +/* PR rtl-optimization/64536 */
> +/* { dg-do link } */
> +/* { dg-options "-O2" } */
> +/* { dg-additional-options "-fPIC" { target fpic } } */
> +
> +struct S { long q; } *h;
> +long a, b, g, j, k, *c, *d, *e, *f, *i;
> +long *baz (void)
> +{
> + asm volatile ("" : : : "memory");
> + return e;
> +}
> +
> +void
> +bar (int x)
> +{
> + int y;
> + for (y = 0; y < x; y++)
> + {
> + switch (b)
> + {
> + case 0:
> + case 2:
> + a++;
> + break;
> + case 3:
> + a++;
> + break;
> + case 1:
> + a++;
> + }
> + if (d)
> + {
> + f = baz ();
> + g = k++;
> + if (&h->q)
> + {
> + j = *f;
> + h->q = *f;
> + }
> + else
> + i = (long *) (h->q = *f);
> + *c++ = (long) f;
> + e += 6;
> + }
> + else
> + {
> + f = baz ();
> + g = k++;
> + if (&h->q)
> + {
> + j = *f;
> + h->q = *f;
> + }
> + else
> + i = (long *) (h->q = *f);
> + *c++ = (long) f;
> + e += 6;
> + }
> + }
> +}
> +
> +int
> +main ()
> +{
> + return 0;
> +}
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Jennifer Guild,
Dilip Upmanyu, Graham Norton HRB 21284 (AG Nuernberg)
