[Bug tree-optimization/52340] New: autopar (at least) corrupts dominance info

[Bug tree-optimization/52340] New: autopar (at least) corrupts dominance info

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52340

             Bug #: 52340
           Summary: autopar (at least) corrupts dominance info
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: rguenth@gcc.gnu.org


Adding sanity-checking to calculate_dominance_info trips over autopar at least:

Index: gcc/dominance.c
===================================================================
--- gcc/dominance.c     (revision 184460)
+++ gcc/dominance.c     (working copy)
@@ -639,7 +639,12 @@ calculate_dominance_info (enum cdi_direc
   bool reverse = (dir == CDI_POST_DOMINATORS) ? true : false;

   if (dom_computed[dir_index] == DOM_OK)
-    return;
+    {
+#ifdef ENABLE_CHECKING
+      verify_dominators (dir);
+#endif
+      return;
+    }

   timevar_push (TV_DOMINANCE);
   if (!dom_info_available_p (dir))
@@ -667,6 +672,10 @@ calculate_dominance_info (enum cdi_direc
       free_dom_info (&di);
       dom_computed[dir_index] = DOM_NO_FAST_QUERY;
     }
+#ifdef ENABLE_CHECKING
+  else
+    verify_dominators (dir);
+#endif

   compute_dom_fast_query (dir);


We notice this in the update_ssa call that computes dominance info
(which is already there, so the verification happens and fails).
A workaround (or fix) for pieces is

Index: gcc/tree-parloops.c
===================================================================
--- gcc/tree-parloops.c (revision 184460)
+++ gcc/tree-parloops.c (working copy)
@@ -1740,6 +1740,10 @@ create_parallel_loop (struct loop *loop,
   gimple_set_location (stmt, loc);
   gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);

+  /* After the above dom info is hosed.  Re-compute it.  */
+  free_dominance_info (CDI_DOMINATORS);
+  calculate_dominance_info (CDI_DOMINATORS);
+
   return paral_bb;
 }

[Bug tree-optimization/52340] autopar (at least) corrupts dominance info

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52340

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org

--- Comment #1 from vries at gcc dot gnu.org ---
https://gcc.gnu.org/ml/gcc-cvs/2012-03/msg00260.html :

Author: rguenth
Date: Mon Mar  5 14:36:18 2012
New Revision: 184933

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=184933
Log:
2012-03-05  Richard Guenther  <rguenther@suse.de>

    * cfgexpand.c (gimple_expand_cfg): Free dominator info.
    * tree-if-conv.c (combine_blocks): Free post-dominator info
    after breaking it.
    * tree-parloops.c (create_parallel_loop): Free and re-compute
    dominator info after breaking it.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgexpand.c
    trunk/gcc/tree-if-conv.c
    trunk/gcc/tree-parloops.c

[Bug tree-optimization/52340] autopar (at least) corrupts dominance info

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52340

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #2 from vries at gcc dot gnu.org ---
patch committed long ago, marking resolved-fixed