2008-05-31 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/34244
	* fold-const.c (tree_expr_nonnegative_warnv_p): Do not ask VRP.
	(tree_expr_nonzero_warnv_p): Likewise.
	* tree-vrp.c (vrp_expr_computes_nonnegative): Call
	ssa_name_nonnegative_p.
	(vrp_expr_computes_nonzero): Call ssa_name_nonzero_p.
	(extract_range_from_unary_expr): Use vrp_expr_computes_nonzero,
	not tree_expr_nonzero_warnv_p.

	PR tree-optimization/36262
	Revert
	2007-11-29  Zdenek Dvorak  <ook@ucw.cz>

        PR tree-optimization/34244
        * tree-vrp.c (adjust_range_with_scev): Clear scev cache.
        (record_numbers_of_iterations): New function.
        (execute_vrp): Cache the numbers of iterations of loops.
        * tree-scalar-evolution.c (scev_reset_except_niters):
        New function.
        (scev_reset): Use scev_reset_except_niters.
        * tree-scalar-evolution.h (scev_reset_except_niters): Declare.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@136237 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 6 insertions, 34 deletions

diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 15e7ee57dd6..fe39a24f096 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -772,7 +772,9 @@ usable_range_p (value_range_t *vr, bool *strict_overflow_p)
 static bool
 vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
 {
-  return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p);
+  return (tree_expr_nonnegative_warnv_p (expr, strict_overflow_p)
+	  || (TREE_CODE (expr) == SSA_NAME
+	      && ssa_name_nonnegative_p (expr)));
 }
 
 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
@@ -781,7 +783,9 @@ vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
 static bool
 vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p)
 {
-  if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p))
+  if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p)
+      || (TREE_CODE (expr) == SSA_NAME
+	  && ssa_name_nonzero_p (expr)))
     return true;
 
   /* If we have an expression of the form &X->a, then the expression
@@ -2799,13 +2803,6 @@ adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
   if (vr->type == VR_ANTI_RANGE)
     return;
 
-  /* Ensure that there are not values in the scev cache based on assumptions
-     on ranges of ssa names that were changed
-     (in set_value_range/set_value_range_to_varying).  Preserve cached numbers
-     of iterations, that were computed before the start of VRP (we do not
-     recompute these each time to save the compile time).  */
-  scev_reset_except_niters ();
-
   chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
 
   /* Like in PR19590, scev can return a constant function.  */
@@ -6636,20 +6633,6 @@ vrp_finalize (void)
   vr_phi_edge_counts = NULL;
 }
 
-/* Calculates number of iterations for all loops, to ensure that they are
-   cached.  */
-
-static void
-record_numbers_of_iterations (void)
-{
-  loop_iterator li;
-  struct loop *loop;
-
-  FOR_EACH_LOOP (li, loop, 0)
-    {
-      number_of_latch_executions (loop);
-    }
-}
 
 /* Main entry point to VRP (Value Range Propagation).  This pass is
    loosely based on J. R. C. Patterson, ``Accurate Static Branch
@@ -6708,17 +6691,6 @@ execute_vrp (void)
 
   insert_range_assertions ();
 
-  /* Compute the # of iterations for each loop before we start the VRP
-     analysis.  The value ranges determined by VRP are used in expression
-     simplification, that is also used by the # of iterations analysis.
-     However, in the middle of the VRP analysis, the value ranges do not take
-     all the possible paths in CFG into account, so they do not have to be
-     correct, and the # of iterations analysis can obtain wrong results.
-     This is a problem, since the results of the # of iterations analysis
-     are cached, so these mistakes would not be corrected when the value
-     ranges are corrected.  */
-  record_numbers_of_iterations ();
-
   to_remove_edges = VEC_alloc (edge, heap, 10);
   to_update_switch_stmts = VEC_alloc (switch_update, heap, 5);