[PATCH] Fix vectorizer ICE (PR tree-optimization/55831)

[Jakub Jelinek]

Hi!

The following testcase ICEs because get_initial_def_for_induction inserts
stmts before gsi_start_bb, which is wrong for basic blocks that start with
labels, as then the labels are in the middle of a basic block.

Ok for trunk?

2012-12-31  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/55831
        * tree-vect-loop.c (get_initial_def_for_induction): Use
        gsi_after_labels instead of gsi_start_bb.

        * gcc.dg/pr55831.c: New test.

--- gcc/tree-vect-loop.c.jj     2012-11-27 14:33:14.000000000 +0100
+++ gcc/tree-vect-loop.c        2012-12-31 15:10:02.211716876 +0100
@@ -3406,7 +3406,7 @@ get_initial_def_for_induction (gimple iv
          build1 (VIEW_CONVERT_EXPR, resvectype, induc_def), NULL_TREE);
       induc_def = make_ssa_name (gimple_assign_lhs (new_stmt), new_stmt);
       gimple_assign_set_lhs (new_stmt, induc_def);
-      si = gsi_start_bb (bb);
+      si = gsi_after_labels (bb);
       gsi_insert_before (&si, new_stmt, GSI_SAME_STMT);
       set_vinfo_for_stmt (new_stmt,
                          new_stmt_vec_info (new_stmt, loop_vinfo, NULL));
--- gcc/testsuite/gcc.dg/pr55831.c.jj   2012-12-31 15:25:11.484514159 +0100
+++ gcc/testsuite/gcc.dg/pr55831.c      2012-12-31 15:13:35.000000000 +0100
@@ -0,0 +1,22 @@
+/* PR tree-optimization/55831 */
+/* { dg-do compile } */
+/* { dg-options "-O -fstrict-overflow -ftree-vectorize -Wno-unused-label" } */
+
+int g;
+short p, q;
+
+void
+f (void)
+{
+  short a = p, b = q, i;
+
+  if (a)
+    {
+    label:
+      for (i = 0; i < 8; i++)
+       b ^= a++;
+
+      if (!b)
+       g = 0;
+    }
+}

        Jakub