[PATCH] Fix PR58955

[Richard Biener]

This fixes the wrong direction of dependence edges in loop
distribution (this happens when you think that if you choose
the wrong direction a testcase will trip and thus you don't
think hard enough ...).

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2013-11-05  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/58955
        * tree-loop-distribution.c (pg_add_dependence_edges): Fix
        edge direction.
        * gcc.dg/torture/pr58955-1.c: New testcase.
        * gcc.dg/torture/pr58955-2.c: Likewise.

Index: gcc/tree-loop-distribution.c
===================================================================
*** gcc/tree-loop-distribution.c        (revision 204388)
--- gcc/tree-loop-distribution.c        (working copy)
*************** pg_add_dependence_edges (struct graph *r
*** 1324,1330 ****
    for (int ii = 0; drs1.iterate (ii, &dr1); ++ii)
      for (int jj = 0; drs2.iterate (jj, &dr2); ++jj)
        {
!       int this_dir = 1;
        ddr_p ddr;
        /* Re-shuffle data-refs to be in dominator order.  */
        if (rdg_vertex_for_stmt (rdg, DR_STMT (dr1))
--- 1324,1330 ----
    for (int ii = 0; drs1.iterate (ii, &dr1); ++ii)
      for (int jj = 0; drs2.iterate (jj, &dr2); ++jj)
        {
!       int this_dir = -1;
        ddr_p ddr;
        /* Re-shuffle data-refs to be in dominator order.  */
        if (rdg_vertex_for_stmt (rdg, DR_STMT (dr1))
Index: gcc/testsuite/gcc.dg/torture/pr58955-1.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr58955-1.c    (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr58955-1.c    (working copy)
***************
*** 0 ****
--- 1,20 ----
+ /* { dg-do run } */
+ 
+ extern void abort (void);
+ 
+ int a, b, c, d[4] = { 0, 0, 0, 1 };
+ 
+ int
+ main ()
+ {
+   for (; a < 4; a++)
+     {
+       int e = d[a];
+       for (c = 1; c < 1; c++);
+       b = e;
+       d[a] = 0;
+     }
+   if (b != 1)
+     abort ();
+   return 0;
+ }
Index: gcc/testsuite/gcc.dg/torture/pr58955-2.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr58955-2.c    (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr58955-2.c    (working copy)
***************
*** 0 ****
--- 1,18 ----
+ /* { dg-do run } */
+ 
+ extern void abort (void);
+ 
+ int a, b[10];
+ 
+ int
+ main ()
+ {
+   for (; a < 2; a++)
+     {
+       b[a] = 1;
+       b[a + 1] = 0;
+     }
+   if (b[1] != 1)
+     abort ();
+   return 0;
+ }