From: Richard Guenther <rguenther@suse.de>
Date: Tue, 4 May 2010 09:53:28 +0000 (+0000)
Subject: re PR tree-optimization/43949 (bogus warning: array subscript is above array bounds)
X-Git-Tag: releases/gcc-4.6.0~7512
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=622d360ecdb6c4dcbe01414f534fa89c61cac451;p=thirdparty%2Fgcc.git

re PR tree-optimization/43949 (bogus warning: array subscript is above array bounds)

2010-05-04  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/43949
	* tree-vrp.c (extract_range_from_binary_expr): Only handle
	TRUNC_MOD_EXPR.

From-SVN: r159020
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 30f3ea13fd9d..4195d9dd6669 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-05-04  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43949
+	* tree-vrp.c (extract_range_from_binary_expr): Only handle
+	TRUNC_MOD_EXPR.
+
 2010-04-26  Jason Merrill  <jason@redhat.com>
 
 	* c.opt (-fstrict-enums): New.
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 83ff665c61d8..8cac4dfc45a0 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -2084,9 +2084,6 @@ extract_range_from_binary_expr (value_range_t *vr,
       && code != EXACT_DIV_EXPR
       && code != ROUND_DIV_EXPR
       && code != TRUNC_MOD_EXPR
-      && code != FLOOR_MOD_EXPR
-      && code != CEIL_MOD_EXPR
-      && code != ROUND_MOD_EXPR
       && code != RSHIFT_EXPR
       && code != MIN_EXPR
       && code != MAX_EXPR
@@ -2156,9 +2153,6 @@ extract_range_from_binary_expr (value_range_t *vr,
       && code != EXACT_DIV_EXPR
       && code != ROUND_DIV_EXPR
       && code != TRUNC_MOD_EXPR
-      && code != FLOOR_MOD_EXPR
-      && code != CEIL_MOD_EXPR
-      && code != ROUND_MOD_EXPR
       && (vr0.type == VR_VARYING
 	  || vr1.type == VR_VARYING
 	  || vr0.type != vr1.type
@@ -2509,27 +2503,30 @@ extract_range_from_binary_expr (value_range_t *vr,
 	    }
 	}
     }
-  else if (code == TRUNC_MOD_EXPR
-	   || code == FLOOR_MOD_EXPR
-	   || code == CEIL_MOD_EXPR
-	   || code == ROUND_MOD_EXPR)
+  else if (code == TRUNC_MOD_EXPR)
     {
       bool sop = false;
-      if (vr0.type == VR_ANTI_RANGE
-	  || vr1.type != VR_RANGE
+      if (vr1.type != VR_RANGE
 	  || symbolic_range_p (&vr1)
-	  || range_includes_zero_p (&vr1))
+	  || range_includes_zero_p (&vr1)
+	  || vrp_val_is_min (vr1.min))
 	{
 	  set_value_range_to_varying (vr);
 	  return;
 	}
       type = VR_RANGE;
-      max = int_const_binop (MINUS_EXPR, vr1.max, integer_one_node, 0);
-      if (vrp_expr_computes_nonnegative (op0, &sop)
-	  && vrp_expr_computes_nonnegative (op1, &sop) && !sop)
-	min = build_int_cst (TREE_TYPE (vr1.max), 0);
+      /* Compute MAX <|vr1.min|, |vr1.max|> - 1.  */
+      max = fold_unary_to_constant (ABS_EXPR, TREE_TYPE (vr1.min), vr1.min);
+      if (tree_int_cst_lt (max, vr1.max))
+	max = vr1.max;
+      max = int_const_binop (MINUS_EXPR, max, integer_one_node, 0);
+      /* If the dividend is non-negative the modulus will be
+	 non-negative as well.  */
+      if (TYPE_UNSIGNED (TREE_TYPE (max))
+	  || (vrp_expr_computes_nonnegative (op0, &sop) && !sop))
+	min = build_int_cst (TREE_TYPE (max), 0);
       else
-	min = fold_unary (NEGATE_EXPR, TREE_TYPE (max), max);
+	min = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (max), max);
     }
   else if (code == MINUS_EXPR)
     {