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?
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
