[Bug tree-optimization/81373] [7/8 Regression] Graphite ICE in ssa_default_def at gcc/tree-dfa.c:305

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81373

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
The following patch fixes this.  We fail to handle scev_analyzable_p
loop-closed
PHIs that are live-out to the region.

Index: gcc/graphite-scop-detection.c
===================================================================
--- gcc/graphite-scop-detection.c       (revision 252968)
+++ gcc/graphite-scop-detection.c       (working copy)
@@ -1717,17 +1717,20 @@ build_cross_bb_scalars_def (scop_p scop,
   if (!def || !is_gimple_reg (def))
     return;

-  /* Do not gather scalar variables that can be analyzed by SCEV as they can
be
-     generated out of the induction variables.  */
-  if (scev_analyzable_p (def, scop->scop_info->region))
-    return;
+  bool scev_analyzable = scev_analyzable_p (def, scop->scop_info->region);

   gimple *use_stmt;
   imm_use_iterator imm_iter;
   FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, def)
-    if ((def_bb != gimple_bb (use_stmt) && !is_gimple_debug (use_stmt))
-       /* PHIs have their effect at "BBs" on the edges.  See PR79622.  */
-       || gimple_code (SSA_NAME_DEF_STMT (def)) == GIMPLE_PHI)
+    /* Do not gather scalar variables that can be analyzed by SCEV as they can
+       be generated out of the induction variables.  */
+    if ((! scev_analyzable
+        /* But gather SESE liveouts as we otherwise fail to rewrite their
+           exit PHIs.  */
+        || ! bb_in_sese_p (gimple_bb (use_stmt), scop->scop_info->region))
+       && ((def_bb != gimple_bb (use_stmt) && !is_gimple_debug (use_stmt))
+           /* PHIs have their effect at "BBs" on the edges.  See PR79622.  */
+           || gimple_code (SSA_NAME_DEF_STMT (def)) == GIMPLE_PHI))
       {
        writes->safe_push (def);
        DEBUG_PRINT (dp << "Adding scalar write: ";