[PATCH] Fix PR79977

[Richard Biener]

This patch fixes SESE merging which can sometimes form a region
that is not SE.

Bootstrap/regtest running on x86_64-unknown-linux-gnu.

Richard.

2017-03-09  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/79977
        * graphite-scop-detection.c (scop_detection::merge_sese):
        Handle the case of extra exits to blocks dominating the entry.

        * gcc.dg/graphite/pr79977.c: New testcase.

Index: gcc/graphite-scop-detection.c
===================================================================
*** gcc/graphite-scop-detection.c       (revision 246002)
--- gcc/graphite-scop-detection.c       (working copy)
*************** scop_detection::merge_sese (sese_l first
*** 817,822 ****
--- 817,841 ----
         != loop_depth (exit->dest->loop_father))
      return invalid_sese;
  
+   /* For now we just bail out when there is a loop exit in the region
+      that is not also the exit of the region.  We could enlarge the
+      region to cover the loop that region exits to.  See PR79977.  */
+   if (loop_outer (entry->src->loop_father))
+     {
+       vec<edge> exits = get_loop_exit_edges (entry->src->loop_father);
+       for (unsigned i = 0; i < exits.length (); ++i)
+       {
+         if (exits[i] != exit
+             && bb_in_region (exits[i]->src, entry->dest, exit->src))
+           {
+             DEBUG_PRINT (dp << "[scop-detection-fail] cannot merge seses.\n");
+             exits.release ();
+             return invalid_sese;
+           }
+       }
+       exits.release ();
+     }
+ 
    /* For now we just want to bail out when exit does not post-dominate entry.
       TODO: We might just add a basic_block at the exit to make exit
       post-dominate entry (the entire region).  */
Index: gcc/testsuite/gcc.dg/graphite/pr79977.c
===================================================================
*** gcc/testsuite/gcc.dg/graphite/pr79977.c     (nonexistent)
--- gcc/testsuite/gcc.dg/graphite/pr79977.c     (working copy)
***************
*** 0 ****
--- 1,27 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -floop-nest-optimize" } */
+ 
+ int uo[3];
+ int di;
+ 
+ void
+ i7 (int mp)
+ {
+   int l4;
+ 
+ wh:
+   while (l4 > 1)
+     {
+       for (di = 0; di < 2; ++di)
+       uo[di] = 0;
+ 
+       for (di = 0; di < 3; ++di)
+       {
+         uo[di] = 0;
+         if (mp != 0)
+           goto wh;
+       }
+ 
+       --l4;
+     }
+ }