re PR tree-optimization/31605 (VRP eliminates a useful test due with conversion from unsigned int to int)

./:	PR tree-optimization/31605
	* tree-vrp.c (set_value_range): Check that min and max are not
	both overflow infinities.
	(set_value_range_to_value): New static function.
	(extract_range_from_binary_expr): Call set_value_range_to_value.
	(extract_range_from_cond_expr): Likewise.
	(extract_range_from_expr): Likewise.
	(extract_range_from_unary_expr): Likewise.  Don't create a range
	which overflows on both sides.
	(vrp_meet): Check for a useless range.
	(vrp_visit_phi_node): If we see a constant which looks like an
	overflow infinity, turn off the TREE_OVERFLOW flag.
testsuite/:
	PR tree-optimizatoin/31605
	* gcc.c-torture/execute/pr31605.c: New test.

From-SVN: r124128

1 files changed, 56 insertions, 7 deletions

diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index e35a6e9..78675e7 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -272,6 +272,10 @@ set_value_range (value_range_t *vr, enum value_range_type t, tree min,
 
       cmp = compare_values (min, max);
       gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
+
+      if (needs_overflow_infinity (TREE_TYPE (min)))
+	gcc_assert (!is_overflow_infinity (min)
+		    || !is_overflow_infinity (max));
     }
 
   if (t == VR_UNDEFINED || t == VR_VARYING)
@@ -320,6 +324,23 @@ set_value_range_to_varying (value_range_t *vr)
     bitmap_clear (vr->equiv);
 }
 
+/* Set value range VR to a single value.  This function is only called
+   with values we get from statements, and exists to clear the
+   TREE_OVERFLOW flag so that we don't think we have an overflow
+   infinity when we shouldn't.  */
+
+static inline void
+set_value_range_to_value (value_range_t *vr, tree val)
+{
+  gcc_assert (is_gimple_min_invariant (val));
+  if (is_overflow_infinity (val))
+    {
+      val = copy_node (val);
+      TREE_OVERFLOW (val) = 0;
+    }
+  set_value_range (vr, VR_RANGE, val, val, NULL);
+}
+
 /* Set value range VR to a non-negative range of type TYPE.
    OVERFLOW_INFINITY indicates whether to use a overflow infinity
    rather than TYPE_MAX_VALUE; this should be true if we determine
@@ -1646,7 +1667,7 @@ extract_range_from_binary_expr (value_range_t *vr, tree expr)
   if (TREE_CODE (op0) == SSA_NAME)
     vr0 = *(get_value_range (op0));
   else if (is_gimple_min_invariant (op0))
-    set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
+    set_value_range_to_value (&vr0, op0);
   else
     set_value_range_to_varying (&vr0);
 
@@ -1654,7 +1675,7 @@ extract_range_from_binary_expr (value_range_t *vr, tree expr)
   if (TREE_CODE (op1) == SSA_NAME)
     vr1 = *(get_value_range (op1));
   else if (is_gimple_min_invariant (op1))
-    set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
+    set_value_range_to_value (&vr1, op1);
   else
     set_value_range_to_varying (&vr1);
 
@@ -2053,7 +2074,7 @@ extract_range_from_unary_expr (value_range_t *vr, tree expr)
   if (TREE_CODE (op0) == SSA_NAME)
     vr0 = *(get_value_range (op0));
   else if (is_gimple_min_invariant (op0))
-    set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
+    set_value_range_to_value (&vr0, op0);
   else
     set_value_range_to_varying (&vr0);
 
@@ -2185,7 +2206,9 @@ extract_range_from_unary_expr (value_range_t *vr, tree expr)
 	min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
       else if (needs_overflow_infinity (TREE_TYPE (expr)))
 	{
-	  if (supports_overflow_infinity (TREE_TYPE (expr)))
+	  if (supports_overflow_infinity (TREE_TYPE (expr))
+	      && !is_overflow_infinity (vr0.min)
+	      && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
 	    min = positive_overflow_infinity (TREE_TYPE (expr));
 	  else
 	    {
@@ -2361,6 +2384,18 @@ extract_range_from_unary_expr (value_range_t *vr, tree expr)
       if (needs_overflow_infinity (TREE_TYPE (expr)))
 	{
 	  gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
+
+	  /* If both sides have overflowed, we don't know
+	     anything.  */
+	  if ((is_overflow_infinity (vr0.min)
+	       || TREE_OVERFLOW (min))
+	      && (is_overflow_infinity (vr0.max)
+		  || TREE_OVERFLOW (max)))
+	    {
+	      set_value_range_to_varying (vr);
+	      return;
+	    }
+
 	  if (is_overflow_infinity (vr0.min))
 	    min = vr0.min;
 	  else if (TREE_OVERFLOW (min))
@@ -2422,7 +2457,7 @@ extract_range_from_cond_expr (value_range_t *vr, tree expr)
   if (TREE_CODE (op0) == SSA_NAME)
     vr0 = *(get_value_range (op0));
   else if (is_gimple_min_invariant (op0))
-    set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
+    set_value_range_to_value (&vr0, op0);
   else
     set_value_range_to_varying (&vr0);
 
@@ -2430,7 +2465,7 @@ extract_range_from_cond_expr (value_range_t *vr, tree expr)
   if (TREE_CODE (op1) == SSA_NAME)
     vr1 = *(get_value_range (op1));
   else if (is_gimple_min_invariant (op1))
-    set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
+    set_value_range_to_value (&vr1, op1);
   else
     set_value_range_to_varying (&vr1);
 
@@ -2494,7 +2529,7 @@ extract_range_from_expr (value_range_t *vr, tree expr)
   else if (TREE_CODE_CLASS (code) == tcc_comparison)
     extract_range_from_comparison (vr, expr);
   else if (is_gimple_min_invariant (expr))
-    set_value_range (vr, VR_RANGE, expr, expr, NULL);
+    set_value_range_to_value (vr, expr);
   else
     set_value_range_to_varying (vr);
 
@@ -5106,6 +5141,14 @@ vrp_meet (value_range_t *vr0, value_range_t *vr1)
       else
 	goto give_up;
 
+      /* Check for useless ranges.  */
+      if (INTEGRAL_TYPE_P (TREE_TYPE (min))
+	  && ((min == TYPE_MIN_VALUE (TREE_TYPE (min))
+	       || is_overflow_infinity (min))
+	      && (max == TYPE_MAX_VALUE (TREE_TYPE (max))
+		  || is_overflow_infinity (max))))
+	goto give_up;
+
       /* The resulting set of equivalences is the intersection of
 	 the two sets.  */
       if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
@@ -5235,6 +5278,12 @@ vrp_visit_phi_node (tree phi)
 	    }
 	  else
 	    {
+	      if (is_overflow_infinity (arg))
+		{
+		  arg = copy_node (arg);
+		  TREE_OVERFLOW (arg) = 0;
+		}
+
 	      vr_arg.type = VR_RANGE;
 	      vr_arg.min = arg;
 	      vr_arg.max = arg;