tree-vrp.c (compare_values_warnv): Check TREE_NO_WARNING on a PLUS_EXPR or…

tree-vrp.c (compare_values_warnv): Check TREE_NO_WARNING on a PLUS_EXPR or MINUS_EXPR node before setting...

./:	* tree-vrp.c (compare_values_warnv): Check TREE_NO_WARNING on a
	PLUS_EXPR or MINUS_EXPR node before setting *strict_overflow_p.
	(extract_range_from_assert): Set TREE_NO_WARNING when creating an
	expression.
	(test_for_singularity): Likewise.
testsuite/:
	* gcc.dg/Wstrict-overflow-19.c: New test.

From-SVN: r125334

gcc/ChangeLog

+2007-06-05  Ian Lance Taylor  <iant@google.com>
+
+	* tree-vrp.c (compare_values_warnv): Check TREE_NO_WARNING on a
+	PLUS_EXPR or MINUS_EXPR node before setting *strict_overflow_p.
+	(extract_range_from_assert): Set TREE_NO_WARNING when creating an
+	expression.
+	(test_for_singularity): Likewise.
+
 2007-06-05  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/constraints.md ("Y2"): Replaced by ...

gcc/testsuite/ChangeLog

+2007-06-05  Ian Lance Taylor  <iant@google.com>
+
+	* gcc.dg/Wstrict-overflow-19.c: New test.
+
 2007-06-05  Razya Ladelsky  <razya@il.ibm.com>
 
 	* gcc.dg/matrix/matrix-6.c: Remove conversion.

gcc/testsuite/gcc.dg/Wstrict-overflow-19.c

+/* { dg-do compile } */
+/* { dg-options "-fstrict-overflow -O2 -Wstrict-overflow" } */
+
+/* Don't warn about an overflow when threading jumps.  We used to get
+   a warning from comparing bounds generated by VRP.  */
+
+int
+bar(int a, int b, int n)
+{
+  if (b > a)
+    n = a - b;
+  if (a >= b)
+    n = 1;
+  return n;
+}

gcc/tree-vrp.c

@@ -837,7 +837,9 @@ compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
       if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
 	return -2;
 
-      if (strict_overflow_p != NULL)
+      if (strict_overflow_p != NULL
+	  && (code1 == SSA_NAME || !TREE_NO_WARNING (val1))
+	  && (code2 == SSA_NAME || !TREE_NO_WARNING (val2)))
 	*strict_overflow_p = true;
 
       if (code1 == SSA_NAME)
@@ -1252,6 +1254,8 @@ extract_range_from_assert (value_range_t *vr_p, tree expr)
 	    {
 	      tree one = build_int_cst (type, 1);
 	      max = fold_build2 (MINUS_EXPR, type, max, one);
+	      if (EXPR_P (max))
+		TREE_NO_WARNING (max) = 1;
 	    }
 
 	  set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
@@ -1285,6 +1289,8 @@ extract_range_from_assert (value_range_t *vr_p, tree expr)
 	    {
 	      tree one = build_int_cst (type, 1);
 	      min = fold_build2 (PLUS_EXPR, type, min, one);
+	      if (EXPR_P (min))
+		TREE_NO_WARNING (min) = 1;
 	    }
 
 	  set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
@@ -5646,6 +5652,8 @@ test_for_singularity (enum tree_code cond_code, tree op0,
 	{
 	  tree one = build_int_cst (TREE_TYPE (op0), 1);
 	  max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
+	  if (EXPR_P (max))
+	    TREE_NO_WARNING (max) = 1;
 	}
     }
   else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
@@ -5659,6 +5667,8 @@ test_for_singularity (enum tree_code cond_code, tree op0,
 	{
 	  tree one = build_int_cst (TREE_TYPE (op0), 1);
 	  min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
+	  if (EXPR_P (min))
+	    TREE_NO_WARNING (min) = 1;
 	}
     }