[backport gcc-4.8/trunk r195007, depends on vrp-uint128_t-range-checking patch <mikpe@it.uu.se>]

Date: Mon, 7 Jan 2013 22:02:23 +0100
From: Jakub Jelinek <jakub at redhat dot com>
Subject: [PATCH] Minor VRP simplify_float_conversion_using_ranges tweaks (PR tree-optimization/54120)
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>

Hi!

As mentioned in the PR, the actual important bug has been fixed in
range_fits_type_p by Richard Sandiford recently, so here are just two minor
nits.  An extension of a signed src_type to unsigned wider type is fine only
if the vr doesn't have negative min or max, so always assuming we can extend
is wrong (but not a very big deal, as we always pass unsigned_p = false
when calling the function right now).
The other change mattered in 4.7 where CODE_FOR_nothing is a big number, in
4.8 it is just a consistency issue when all the other can_float_p calls
are compared with CODE_FOR_nothing (== 0).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

What about 4.7 (together with backport of Richard's
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194800 fix) after a while?

gcc/

2013-01-08  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/54120
	* tree-vrp.c (range_fits_type_p): Don't allow
	src_precision < precision from signed vr to unsigned_p
	if vr->min or vr->max is negative.
	(simplify_float_conversion_using_ranges): Test can_float_p
	against CODE_FOR_nothing.

--- gcc-4.7.2/gcc/tree-vrp.c.~1~	2013-02-02 15:03:54.079100877 +0100
+++ gcc-4.7.2/gcc/tree-vrp.c	2013-02-02 15:11:11.617846147 +0100
@@ -7365,9 +7365,11 @@ range_fits_type_p (value_range_t *vr, un
       && !POINTER_TYPE_P (src_type))
     return false;
 
-  /* An extension is always fine, so is an identity transform.  */
+  /* An extension is fine unless VR is signed and unsigned_p,
+     and so is an identity transform.  */
   src_precision = TYPE_PRECISION (TREE_TYPE (vr->min));
-  if (src_precision < precision
+  if ((src_precision < precision
+       && !(unsigned_p && !TYPE_UNSIGNED (src_type)))
       || (src_precision == precision
 	  && TYPE_UNSIGNED (src_type) == unsigned_p))
     return true;
@@ -7425,7 +7427,7 @@ simplify_float_conversion_using_ranges (
     mode = TYPE_MODE (TREE_TYPE (rhs1));
   /* If we can do the conversion in the current input mode do nothing.  */
   else if (can_float_p (fltmode, TYPE_MODE (TREE_TYPE (rhs1)),
-			TYPE_UNSIGNED (TREE_TYPE (rhs1))))
+			TYPE_UNSIGNED (TREE_TYPE (rhs1))) != CODE_FOR_nothing)
     return false;
   /* Otherwise search for a mode we can use, starting from the narrowest
      integer mode available.  */