[PATCH] Call estimate_numbers_of_iterations after insert_range_assertions (PR tree-optimization/49419)

[Jakub Jelinek]

Hi!

The following testcase is miscompiled e.g. on powerpc (not on x86_64/i686
due to different ivopts choices), because estimate_numbers_of_iterations
was called before assert_exprs are added to the IL and gets info cached
until adjust_range_with_scev, where using the original SSA_NAMEs leads
to problems where VR changes might not be propagated properly.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk/4.6?  I'll work on followup improvements for the trunk
afterwards.

2011-06-15  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/49419
	* tree-vrp.c (execute_vrp): Call init_range_assertions
	before estimate_numbers_of_iterations, call
	free_number_of_iterations_estimates before calling
	remove_range_assertions.

	* gcc.c-torture/execute/pr49419.c: New test.

--- gcc/tree-vrp.c.jj	2011-05-31 08:03:10.000000000 +0200
+++ gcc/tree-vrp.c	2011-06-15 17:25:32.000000000 +0200
@@ -7730,14 +7730,14 @@ execute_vrp (void)
   rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
   scev_initialize ();
 
+  insert_range_assertions ();
+
   /* Estimate number of iterations - but do not use undefined behavior
      for this.  We can't do this lazily as other functions may compute
      this using undefined behavior.  */
   free_numbers_of_iterations_estimates ();
   estimate_numbers_of_iterations (false);
 
-  insert_range_assertions ();
-
   to_remove_edges = VEC_alloc (edge, heap, 10);
   to_update_switch_stmts = VEC_alloc (switch_update, heap, 5);
   threadedge_initialize_values ();
@@ -7746,6 +7746,8 @@ execute_vrp (void)
   ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
   vrp_finalize ();
 
+  free_numbers_of_iterations_estimates ();
+
   /* ASSERT_EXPRs must be removed before finalizing jump threads
      as finalizing jump threads calls the CFG cleanup code which
      does not properly handle ASSERT_EXPRs.  */
--- gcc/testsuite/gcc.c-torture/execute/pr49419.c.jj	2011-06-15 18:06:43.000000000 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr49419.c	2011-06-15 18:05:18.000000000 +0200
@@ -0,0 +1,38 @@
+/* PR tree-optimization/49419 */
+
+extern void abort (void);
+
+struct S { int w, x, y; } *t;
+
+int
+foo (int n, int f, int *s, int m)
+{
+  int x, i, a;
+  if (n == -1)
+    return 0;
+  for (x = n, i = 0; t[x].w == f && i < m; i++)
+    x = t[x].x;
+  if (i == m)
+    abort ();
+  a = i + 1;
+  for (x = n; i > 0; i--)
+    {
+      s[i] = t[x].y;
+      x = t[x].x;
+    }
+  s[0] = x;
+  return a;
+}
+
+int
+main (void)
+{
+  int s[3], i;
+  struct S buf[3] = { { 1, 1, 2 }, { 0, 0, 0 }, { 0, 0, 0 } };
+  t = buf;
+  if (foo (0, 1, s, 3) != 2)
+    abort ();
+  if (s[0] != 1 || s[1] != 2)
+    abort ();
+  return 0;
+}

	Jakub