re PR tree-optimization/81373 (Graphite ICE in ssa_default_def at gcc/tree-dfa.c:305)

2017-09-20  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/81373
	* graphite-scop-detection.c (build_cross_bb_scalars_def):
	Force SESE live-out defs to be handled even if they are
	scev_analyzable_p.

	* gcc.dg/graphite/pr81373.c: New testcase.

From-SVN: r253000

gcc/ChangeLog

+2017-09-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/81373
+	* graphite-scop-detection.c (build_cross_bb_scalars_def):
+	Force SESE live-out defs to be handled even if they are
+	scev_analyzable_p.
+
 2017-09-19  Jeff Law  <law@redhat.com>
 
 	* combine-stack-adj.c (combine_stack_adjustments_for_block): Do

gcc/graphite-scop-detection.c

@@ -1717,17 +1717,20 @@ build_cross_bb_scalars_def (scop_p scop, tree def, basic_block def_bb,
   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: ";

gcc/testsuite/ChangeLog

+2017-09-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/81373
+	* gcc.dg/graphite/pr81373.c: New testcase.
+
 2017-09-19  Jeff Law  <law@redhat.com>
 
 	* gcc.target/i386/stack-check-11.c: New test.

gcc/testsuite/gcc.dg/graphite/pr81373.c

+/* { dg-options "-fno-tree-scev-cprop -fgraphite-identity -O -fdump-tree-graphite-all" } */
+
+void bar (void);
+
+int toto()
+{
+  int i, j, k;
+  int a[101][100];
+  int b[100];
+
+  for (i = 1; i < 100; i++)
+    {
+      for (j = 1; j < 100; j++)
+	for (k = 1; k < 100; k++)
+	  a[j][k] = a[j+1][i-1] + 2;
+
+      b[i] = b[i-1] + 2;
+
+      bar ();
+
+      for (j = 1; j < 100; j++)
+	a[j][i] = a[j+1][i-1] + 2;
+
+      b[i] = b[i-1] + 2;
+
+      bar ();
+
+      for (j = 1; j < 100; j++)
+	a[j][i] = a[j+1][i-1] + 2;
+
+      b[i] = a[i-1][i] + 2;
+
+      for (j = 1; j < 100; j++)
+	a[j][i] = a[j+1][i-1] + 2;
+    }
+
+  return a[3][5] + b[1];
+}
+
+/* { dg-final { scan-tree-dump-times "number of SCoPs: 2" 1 "graphite"} } */