2011-07-26 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/49840
	* tree-vrp.c (range_fits_type_p): Properly handle full
	double-int precision.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@176790 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 30 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7825a25882f..74f58cdde69 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2011-07-26  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/49840
+	* tree-vrp.c (range_fits_type_p): Properly handle full
+	double-int precision.
+
 2011-07-26  Martin Jambor  <mjambor@suse.cz>
 
 	PR bootstrap/49786
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index c6a4c4476ff..1756dd25bd3 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -7423,18 +7423,40 @@ simplify_conversion_using_ranges (gimple stmt)
 static bool
 range_fits_type_p (value_range_t *vr, unsigned precision, bool unsigned_p)
 {
+  tree src_type;
+  unsigned src_precision;
   double_int tem;
 
-  /* We can only handle constant ranges.  */
+  /* We can only handle integral and pointer types.  */
+  src_type = TREE_TYPE (vr->min);
+  if (!INTEGRAL_TYPE_P (src_type)
+      && !POINTER_TYPE_P (src_type))
+    return false;
+
+  /* An extension is always fine, so is an identity transform.  */
+  src_precision = TYPE_PRECISION (TREE_TYPE (vr->min));
+  if (src_precision < precision
+      || (src_precision == precision
+	  && TYPE_UNSIGNED (src_type) == unsigned_p))
+    return true;
+
+  /* Now we can only handle ranges with constant bounds.  */
   if (vr->type != VR_RANGE
       || TREE_CODE (vr->min) != INTEGER_CST
       || TREE_CODE (vr->max) != INTEGER_CST)
     return false;
 
+  /* For precision-preserving sign-changes the MSB of the double-int
+     has to be clear.  */
+  if (src_precision == precision
+      && (TREE_INT_CST_HIGH (vr->min) | TREE_INT_CST_HIGH (vr->max)) < 0)
+    return false;
+
+  /* Then we can perform the conversion on both ends and compare
+     the result for equality.  */
   tem = double_int_ext (tree_to_double_int (vr->min), precision, unsigned_p);
   if (!double_int_equal_p (tree_to_double_int (vr->min), tem))
     return false;
-
   tem = double_int_ext (tree_to_double_int (vr->max), precision, unsigned_p);
   if (!double_int_equal_p (tree_to_double_int (vr->max), tem))
     return false;