tree-vrp.c (extract_range_from_unary_expr): Derive ranges for type conversions of a VR_VARYING source to a wider type.

	* tree-vrp.c (extract_range_from_unary_expr): Derive ranges for
	type conversions of a VR_VARYING source to a wider type.

	* gcc.dg/tree-ssa/vrp28.c: New test.

From-SVN: r112256

4 files changed, 81 insertions, 17 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 176ce656..0a8feca 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2006-03-21  Jeff Law  <law@redhat.com>
+
+	* tree-vrp.c (extract_range_from_unary_expr): Derive ranges for
+	type conversions of a VR_VARYING source to a wider type.
+
 2006-03-21  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	* config.gcc (i[34567]86-*-solaris2*): Add config/sol2-10.h to
@@ -106,7 +111,6 @@
 	* tree-ssa-structalias.c (intra_create_variable_infos): Fortran
 	alias semantics is specified by flag_argument_noalias > 2.
 
-2006-03-20  Jeff Law  <law@redhat.com>
 
 	* tree-pass.h (pass_phi_only_copy_prop): Delete.
 	(pass_phi_only_cprop): Declare.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 372ab8c..4726020 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2006-03-21  Jeff Law  <law@redhat.com>
+
+	* gcc.dg/tree-ssa/vrp28.c: New test.
+
 2006-03-21  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	* gcc.dg/builtins-config.h (Solaris case): Define HAVE_C99_RUNTIME
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp28.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp28.c
new file mode 100644
index 0000000..6b2a1fd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp28.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp1" } */
+
+int f(_Bool a)
+{
+  int t = a;
+  if (t != 2)
+   return 0;
+  return 1;
+}
+
+int f1(unsigned char a)
+{
+  int t = a;
+  if (t != 256)
+   return 0;
+  return 1;
+}
+
+int f3 (unsigned char c)
+{
+  int i = c;
+  if (i < 0 || i > 255)
+    return -1;
+  else
+    return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "if " 0 "vrp1" } } * /
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
+
+
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 278347d..d3d57ed 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -1641,14 +1641,12 @@ extract_range_from_unary_expr (value_range_t *vr, tree expr)
       return;
     }
 
-  /* Refuse to operate on varying and symbolic ranges.  Also, if the
-     operand is neither a pointer nor an integral type, set the
-     resulting range to VARYING.  TODO, in some cases we may be able
-     to derive anti-ranges (like nonzero values).  */
-  if (vr0.type == VR_VARYING
-      || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
-	  && !POINTER_TYPE_P (TREE_TYPE (op0)))
-      || symbolic_range_p (&vr0))
+  /* Refuse to operate on symbolic ranges, or if neither operand is
+     a pointer or integral type.  */
+  if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
+       && !POINTER_TYPE_P (TREE_TYPE (op0)))
+      || (vr0.type != VR_VARYING
+	  && symbolic_range_p (&vr0)))
     {
       set_value_range_to_varying (vr);
       return;
@@ -1681,20 +1679,36 @@ extract_range_from_unary_expr (value_range_t *vr, tree expr)
 	 or equal to the new max, then we can safely use the newly
 	 computed range for EXPR.  This allows us to compute
 	 accurate ranges through many casts.  */
-      if (vr0.type == VR_RANGE)
+      if (vr0.type == VR_RANGE
+	  || (vr0.type == VR_VARYING
+	      && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
 	{
-	  tree new_min, new_max;
+	  tree new_min, new_max, orig_min, orig_max;
 
-	  /* Convert VR0's min/max to OUTER_TYPE.  */
-	  new_min = fold_convert (outer_type, vr0.min);
-	  new_max = fold_convert (outer_type, vr0.max);
+	  /* Convert the input operand min/max to OUTER_TYPE.   If
+	     the input has no range information, then use the min/max
+	     for the input's type.  */
+	  if (vr0.type == VR_RANGE)
+	    {
+	      orig_min = vr0.min;
+	      orig_max = vr0.max;
+	    }
+	  else
+	    {
+	      orig_min = TYPE_MIN_VALUE (inner_type);
+	      orig_max = TYPE_MAX_VALUE (inner_type);
+	    }
+
+	  new_min = fold_convert (outer_type, orig_min);
+	  new_max = fold_convert (outer_type, orig_max);
 
 	  /* Verify the new min/max values are gimple values and
-	     that they compare equal to VR0's min/max values.  */
+	     that they compare equal to the orignal input's
+	     min/max values.  */
 	  if (is_gimple_val (new_min)
 	      && is_gimple_val (new_max)
-	      && tree_int_cst_equal (new_min, vr0.min)
-	      && tree_int_cst_equal (new_max, vr0.max)
+	      && tree_int_cst_equal (new_min, orig_min)
+	      && tree_int_cst_equal (new_max, orig_max)
 	      && compare_values (new_min, new_max) <= 0
 	      && compare_values (new_min, new_max) >= -1)
 	    {
@@ -1717,6 +1731,16 @@ extract_range_from_unary_expr (value_range_t *vr, tree expr)
 	}
     }
 
+  /* Conversion of a VR_VARYING value to a wider type can result
+     in a usable range.  So wait until after we've handled conversions
+     before dropping the result to VR_VARYING if we had a source
+     operand that is VR_VARYING.  */
+  if (vr0.type == VR_VARYING)
+    {
+      set_value_range_to_varying (vr);
+      return;
+    }
+
   /* Apply the operation to each end of the range and see what we end
      up with.  */
   if (code == NEGATE_EXPR