re PR tree-optimization/81354 (Segmentation fault in SSA Strength Reduction using -O3)

[gcc]

2017-08-08  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/81354
	* gimple-ssa-strength-reduction.c (create_add_on_incoming_edge):
	Insert on edges rather than explicitly creating landing pads.
	(analyze_candidates_and_replace): Commit edge inserts.


[gcc/testsuite]

2017-08-08  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/81354
	* g++.dg/torture/pr81354.C: New file.

From-SVN: r250955

gcc/ChangeLog

+2017-08-08  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+	PR tree-optimization/81354
+	* g++.dg/torture/pr81354.C: New file.
+
 2017-08-08  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/81719

gcc/gimple-ssa-strength-reduction.c

@@ -2224,8 +2224,6 @@ create_add_on_incoming_edge (slsr_cand_t c, tree basis_name,
 			     widest_int increment, edge e, location_t loc,
 			     bool known_stride)
 {
-  basic_block insert_bb;
-  gimple_stmt_iterator gsi;
   tree lhs, basis_type;
   gassign *new_stmt, *cast_stmt = NULL;
 
@@ -2294,39 +2292,25 @@ create_add_on_incoming_edge (slsr_cand_t c, tree basis_name,
       }
     }
 
-  insert_bb = single_succ_p (e->src) ? e->src : split_edge (e);
-  gsi = gsi_last_bb (insert_bb);
-
-  if (!gsi_end_p (gsi) && stmt_ends_bb_p (gsi_stmt (gsi)))
+  if (cast_stmt)
     {
-      gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
-      if (cast_stmt)
-	{
-	  gsi_insert_before (&gsi, cast_stmt, GSI_SAME_STMT);
-	  gimple_set_location (cast_stmt, loc);
-	}
-    }
-  else
-    {
-      if (cast_stmt)
-	{
-	  gsi_insert_after (&gsi, cast_stmt, GSI_NEW_STMT);
-	  gimple_set_location (cast_stmt, loc);
-	}
-      gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+      gimple_set_location (cast_stmt, loc);
+      gsi_insert_on_edge (e, cast_stmt);
     }
 
   gimple_set_location (new_stmt, loc);
+  gsi_insert_on_edge (e, new_stmt);
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
       if (cast_stmt)
 	{
-	  fprintf (dump_file, "Inserting cast in block %d: ",
-		   insert_bb->index);
+	  fprintf (dump_file, "Inserting cast on edge %d->%d: ",
+		   e->src->index, e->dest->index);
 	  print_gimple_stmt (dump_file, cast_stmt, 0);
 	}
-      fprintf (dump_file, "Inserting in block %d: ", insert_bb->index);
+      fprintf (dump_file, "Inserting on edge %d->%d: ", e->src->index,
+	       e->dest->index);
       print_gimple_stmt (dump_file, new_stmt, 0);
     }
 
@@ -3770,6 +3754,10 @@ analyze_candidates_and_replace (void)
 	  free (incr_vec);
 	}
     }
+
+  /* For conditional candidates, we may have uncommitted insertions
+     on edges to clean up.  */
+  gsi_commit_edge_inserts ();
 }
 
 namespace {

gcc/testsuite/ChangeLog

+2017-08-08  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+	PR tree-optimization/81354
+	* g++.dg/torture/pr81354.C: New file.
+
 2017-08-08  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/81719

gcc/testsuite/g++.dg/torture/pr81354.C

+// PR81354 reported this test as crashing in a limited range of revisions.
+// { dg-do compile }
+
+struct T { double a; double b; };
+
+void foo(T Ad[], int As[2])
+{
+  int j;
+  int i;
+  int Bs[2] = {0,0};
+  T Bd[16];
+
+  for (j = 0; j < 4; j++) {
+    for (i = 0; i + 1 <= j + 1; i++) {
+      Ad[i + As[0] * j] = Bd[i + Bs[0] * j];
+    }
+
+    i = j + 1;  // <- comment out this line and it does not crash
+    for (; i + 1 < 5; i++) {
+      Ad[i + As[0] * j].a = 0.0;
+      Ad[i + As[0] * j].b = 0.0;
+    }
+  }
+}