re PR tree-optimization/92241 (ice in vect_mark_pattern_st mts, at tree-vect-patterns.c:5175)

2019-10-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92241
	* tree-vect-loop.c (vect_fixup_scalar_cycles_with_patterns): When
	we failed to update the reduction index do not use the pattern
	stmts for the reduction chain.
	(vectorizable_reduction): When the reduction chain is corrupt,
	fail.
	* tree-vect-patterns.c (vect_mark_pattern_stmts): Stop when we
	fail to update the reduction chain.

	* gcc.dg/torture/pr92241.c: New testcase.

From-SVN: r277516

gcc/ChangeLog

 2019-10-28  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/92241
+	* tree-vect-loop.c (vect_fixup_scalar_cycles_with_patterns): When
+	we failed to update the reduction index do not use the pattern
+	stmts for the reduction chain.
+	(vectorizable_reduction): When the reduction chain is corrupt,
+	fail.
+	* tree-vect-patterns.c (vect_mark_pattern_stmts): Stop when we
+	fail to update the reduction chain.
+
+2019-10-28  Richard Biener  <rguenther@suse.de>
+
 	* tree-vect-loop.c (vect_create_epilog_for_reduction): Use
 	STMT_VINFO_REDUC_IDX from the actual stmt.
 	(vect_transform_reduction): Likewise.

gcc/testsuite/ChangeLog

+2019-10-28  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/92241
+	* gcc.dg/torture/pr92241.c: New testcase.
+
 2019-10-28  Uroš Bizjak  <ubizjak@gmail.com>
 
 	PR target/92225

gcc/testsuite/gcc.dg/torture/pr92241.c

+/* { dg-do compile } */
+/* { dg-additional-options "-ftree-vectorize" } */
+
+int a, b;
+char c[2];
+void d() {
+  char e;
+  for (; b; b--) {
+    e = 0;
+    for (; e <= 1; e++)
+      a &= c[b + e] && 1;
+  }
+}

gcc/tree-vect-loop.c

@@ -689,13 +689,16 @@ vect_fixup_scalar_cycles_with_patterns (loop_vec_info loop_vinfo)
 	stmt_vec_info next = REDUC_GROUP_NEXT_ELEMENT (first);
 	while (next)
 	  {
-	    if (! STMT_VINFO_IN_PATTERN_P (next))
+	    if (! STMT_VINFO_IN_PATTERN_P (next)
+		|| STMT_VINFO_REDUC_IDX (STMT_VINFO_RELATED_STMT (next)) == -1)
 	      break;
 	    next = REDUC_GROUP_NEXT_ELEMENT (next);
 	  }
-	/* If not all stmt in the chain are patterns try to handle
-	   the chain without patterns.  */
-	if (! next)
+	/* If not all stmt in the chain are patterns or if we failed
+	   to update STMT_VINFO_REDUC_IDX try to handle the chain
+	   without patterns.  */
+	if (! next
+	    && STMT_VINFO_REDUC_IDX (STMT_VINFO_RELATED_STMT (first)) != -1)
 	  {
 	    vect_fixup_reduc_chain (first);
 	    LOOP_VINFO_REDUCTION_CHAINS (loop_vinfo)[i]
@@ -5730,7 +5733,13 @@ vectorizable_reduction (stmt_vec_info stmt_info, slp_tree slp_node,
     {
       stmt_vec_info def = loop_vinfo->lookup_def (reduc_def);
       def = vect_stmt_to_vectorize (def);
-      gcc_assert (STMT_VINFO_REDUC_IDX (def) != -1);
+      if (STMT_VINFO_REDUC_IDX (def) == -1)
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			     "reduction chain broken by patterns.\n");
+	  return false;
+	}
       if (!REDUC_GROUP_FIRST_ELEMENT (def))
 	only_slp_reduc_chain = false;
       reduc_def = gimple_op (def->stmt, 1 + STMT_VINFO_REDUC_IDX (def));

gcc/tree-vect-patterns.c

@@ -5110,6 +5110,9 @@ vect_mark_pattern_stmts (stmt_vec_info orig_stmt_info, gimple *pattern_stmt,
     for (gimple_stmt_iterator si = gsi_start (def_seq);
 	 !gsi_end_p (si); gsi_next (&si))
       {
+	if (dump_enabled_p ())
+	  dump_printf_loc (MSG_NOTE, vect_location,
+			   "extra pattern stmt: %G", gsi_stmt (si));
 	stmt_vec_info pattern_stmt_info
 	  = vect_init_pattern_stmt (gsi_stmt (si),
 				    orig_stmt_info, pattern_vectype);
@@ -5169,10 +5172,13 @@ vect_mark_pattern_stmts (stmt_vec_info orig_stmt_info, gimple *pattern_stmt,
 		found = true;
 		break;
 	      }
-	  if (found && s == pattern_stmt)
-	    break;
 	  if (s == pattern_stmt)
-	    gcc_unreachable ();
+	    {
+	      if (!found && dump_enabled_p ())
+		dump_printf_loc (MSG_NOTE, vect_location,
+				 "failed to update reduction index.\n");
+	      break;
+	    }
 	  if (gsi_end_p (si))
 	    s = pattern_stmt;
 	  else