Marek Polacek <pola...@redhat.com> wrote:
>On Tue, Jan 22, 2013 at 06:44:40PM +0100, Zdenek Dvorak wrote:
>> > I was however worried that we might end up with an edge
>> > coming out of BB
>> > from different loop heading into the header. In this case setting
>up
>> > loop's latch as the source of the latch edge would be wrong.
>>
>> Actually, the comment suggesting that possibility does not make much
>sense.
>> A latch (a predecessor of the header H that is dominated by H)
>belongs to
>> the loop headed by H by definition, so I am not quite sure what the
>test was supposed to do.
>>
>> The latch block may of course belong to a subloop of the loop, but
>that is not
>> forbidden (and it is taken care of further in fix_loop_structure
>through force_single_succ_latches
>> in the situations where we want to avoid this possibility),
>
>Well, okay then, thanks. So below is the new version of the patch.
>Regtested/bootstrapped on x86_64-linux again, ok for trunk?
>
>Richi, are you with this one?
Yes. I cannot quite remember why I added this extra test. Maybe it's in the
place I mostly copied this code from as well.
Thanks,
Richard.
>2013-01-22 Marek Polacek <pola...@redhat.com>
>
> * cfgloopmanip.c (fix_loop_structure): Remove redundant condition.
>
> * testsuite/gcc.dg/pr56035.c: New test.
>
>--- gcc/cfgloopmanip.c.mp 2013-01-22 14:11:25.241233824 +0100
>+++ gcc/cfgloopmanip.c 2013-01-22 19:00:39.850689745 +0100
>@@ -1823,10 +1823,8 @@ fix_loop_structure (bitmap changed_bbs)
> /* If there was no latch, schedule the loop for removal. */
> if (!first_latch)
> loop->header = NULL;
>- /* If there was a single latch and it belongs to the loop of the
>- header, record it. */
>- else if (latch
>- && latch->src->loop_father == loop)
>+ /* If there was a single latch, record it. */
>+ else if (latch)
> loop->latch = latch->src;
> /* Otherwise there are multiple latches which are eventually
> disambiguated below. */
>--- gcc/testsuite/gcc.dg/pr56035.c.mp 2013-01-22 14:27:21.104614758
>+0100
>+++ gcc/testsuite/gcc.dg/pr56035.c 2013-01-22 14:31:01.642266091 +0100
>@@ -0,0 +1,35 @@
>+/* PR tree-optimization/56035 */
>+/* { dg-do compile } */
>+/* { dg-options "-O1 -ftree-vectorize -fcse-follow-jumps
>-fstrict-overflow" } */
>+
>+short a, c, *p;
>+
>+void
>+f (void)
>+{
>+ int b;
>+
>+ if (c)
>+ lbl1:
>+ for (a = 0; a < 1; a++)
>+ {
>+ for (c = 0; c < 1; c++)
>+ {
>+ goto lbl1;
>+ while (*p++)
>+ lbl2:
>+ ;
>+ }
>+ }
>+
>+ for (;; b++)
>+ {
>+ if (c)
>+ goto lbl2;
>+ lbl3:
>+ for (c = 0; c < 9; c++)
>+ for (c = -17; c < 2; c++)
>+ if (*p)
>+ goto lbl3;
>+ }
>+}
>
> Marek
