[gcc r13-2810] frange: drop endpoints to min/max representable numbers for -ffinite-math-only.

[gcc r13-2810] frange: drop endpoints to min/max representable numbers for -ffinite-math-only.

[Aldy Hernandez]

https://gcc.gnu.org/g:b7fd7fb5011106c062df9275ca8fddcbce4ebdeb

commit r13-2810-gb7fd7fb5011106c062df9275ca8fddcbce4ebdeb
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Thu Sep 22 18:20:39 2022 +0200

    frange: drop endpoints to min/max representable numbers for -ffinite-math-only.
    
    Similarly to how we drop NANs to UNDEFINED when -ffinite-math-only, I
    think we can drop the numbers outside of the min/max representable
    numbers to the representable number.
    
    This means the endpoings to VR_VARYING for -ffinite-math-only can now
    be the min/max representable, instead of -INF and +INF.
    
    Saturating in the setter means that the upcoming implementation for
    binary operators no longer have to worry about doing the right
    thing for -ffinite-math-only.  If the range goes outside the limits,
    it'll get chopped down.
    
    Tested on x86-64 Linux.
    
    gcc/ChangeLog:
    
            * range-op-float.cc (build_le): Use vrp_val_*.
            (build_lt): Same.
            (build_ge): Same.
            (build_gt): Same.
            * value-range.cc (frange::set): Chop ranges outside of the
            representable numbers for -ffinite-math-only.
            (frange::normalize_kind): Use vrp_val*.
            (frange::verify_range): Same.
            (frange::set_nonnegative): Same.
            (range_tests_floats): Remove tests that depend on -INF and +INF.
            * value-range.h (real_max_representable): Add prototype.
            (real_min_representable): Same.
            (vrp_val_max): Set max representable number for
            -ffinite-math-only.
            (vrp_val_min): Same but for min.
            (frange::set_varying): Use vrp_val*.

Diff:
---
 gcc/range-op-float.cc | 18 +++++++------
 gcc/value-range.cc    | 46 +++++++++++++++----------------
 gcc/value-range.h     | 75 ++++++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 94 insertions(+), 45 deletions(-)

diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index aa5b7ed073d..6e9d51d3b4b 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -200,8 +200,7 @@ frelop_early_resolve (irange &r, tree type,
 static inline void
 frange_drop_inf (frange &r, tree type)
 {
-  REAL_VALUE_TYPE max;
-  real_max_representable (&max, type);
+  REAL_VALUE_TYPE max = real_max_representable (type);
   frange tmp (type, r.lower_bound (), max);
   r.intersect (tmp);
 }
@@ -212,8 +211,7 @@ frange_drop_inf (frange &r, tree type)
 static inline void
 frange_drop_ninf (frange &r, tree type)
 {
-  REAL_VALUE_TYPE min;
-  real_min_representable (&min, type);
+  REAL_VALUE_TYPE min = real_min_representable (type);
   frange tmp (type, min, r.upper_bound ());
   r.intersect (tmp);
 }
@@ -242,7 +240,8 @@ build_le (frange &r, tree type, const frange &val)
 {
   gcc_checking_assert (!val.known_isnan ());
 
-  r.set (type, dconstninf, val.upper_bound ());
+  REAL_VALUE_TYPE ninf = frange_val_min (type);
+  r.set (type, ninf, val.upper_bound ());
 
   // Add both zeros if there's the possibility of zero equality.
   frange_add_zeros (r, type);
@@ -267,7 +266,8 @@ build_lt (frange &r, tree type, const frange &val)
       return false;
     }
   // We only support closed intervals.
-  r.set (type, dconstninf, val.upper_bound ());
+  REAL_VALUE_TYPE ninf = frange_val_min (type);
+  r.set (type, ninf, val.upper_bound ());
   return true;
 }
 
@@ -278,7 +278,8 @@ build_ge (frange &r, tree type, const frange &val)
 {
   gcc_checking_assert (!val.known_isnan ());
 
-  r.set (type, val.lower_bound (), dconstinf);
+  REAL_VALUE_TYPE inf = frange_val_max (type);
+  r.set (type, val.lower_bound (), inf);
 
   // Add both zeros if there's the possibility of zero equality.
   frange_add_zeros (r, type);
@@ -304,7 +305,8 @@ build_gt (frange &r, tree type, const frange &val)
     }
 
   // We only support closed intervals.
-  r.set (type, val.lower_bound (), dconstinf);
+  REAL_VALUE_TYPE inf = frange_val_max (type);
+  r.set (type, val.lower_bound (), inf);
   return true;
 }
 
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 7e8028eced2..43905ba4901 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -338,6 +338,18 @@ frange::set (tree min, tree max, value_range_kind kind)
       m_neg_nan = false;
     }
 
+  // For -ffinite-math-only we can drop ranges outside the
+  // representable numbers to min/max for the type.
+  if (flag_finite_math_only)
+    {
+      REAL_VALUE_TYPE min_repr = frange_val_min (m_type);
+      REAL_VALUE_TYPE max_repr = frange_val_max (m_type);
+      if (real_less (&m_min, &min_repr))
+	m_min = min_repr;
+      if (real_less (&max_repr, &m_max))
+	m_max = max_repr;
+    }
+
   // Check for swapped ranges.
   gcc_checking_assert (tree_compare (LE_EXPR, min, max));
 
@@ -371,8 +383,8 @@ bool
 frange::normalize_kind ()
 {
   if (m_kind == VR_RANGE
-      && real_isinf (&m_min, 1)
-      && real_isinf (&m_max, 0))
+      && frange_val_is_min (m_min, m_type)
+      && frange_val_is_max (m_max, m_type))
     {
       if (m_pos_nan && m_neg_nan)
 	{
@@ -385,8 +397,8 @@ frange::normalize_kind ()
       if (!m_pos_nan || !m_neg_nan)
 	{
 	  m_kind = VR_RANGE;
-	  m_min = dconstninf;
-	  m_max = dconstinf;
+	  m_min = frange_val_min (m_type);
+	  m_max = frange_val_max (m_type);
 	  return true;
 	}
     }
@@ -706,8 +718,8 @@ frange::verify_range ()
     case VR_VARYING:
       gcc_checking_assert (m_type);
       gcc_checking_assert (m_pos_nan && m_neg_nan);
-      gcc_checking_assert (real_isinf (&m_min, 1));
-      gcc_checking_assert (real_isinf (&m_max, 0));
+      gcc_checking_assert (frange_val_is_min (m_min, m_type));
+      gcc_checking_assert (frange_val_is_max (m_max, m_type));
       return;
     case VR_RANGE:
       gcc_checking_assert (m_type);
@@ -732,7 +744,8 @@ frange::verify_range ()
   // If all the properties are clear, we better not span the entire
   // domain, because that would make us varying.
   if (m_pos_nan && m_neg_nan)
-    gcc_checking_assert (!real_isinf (&m_min, 1) || !real_isinf (&m_max, 0));
+    gcc_checking_assert (!frange_val_is_min (m_min, m_type)
+			 || !frange_val_is_max (m_max, m_type));
 }
 
 // We can't do much with nonzeros yet.
@@ -779,7 +792,7 @@ frange::zero_p () const
 void
 frange::set_nonnegative (tree type)
 {
-  set (type, dconst0, dconstinf);
+  set (type, dconst0, frange_val_max (type));
 
   // Set +NAN as the only possibility.
   if (HONOR_NANS (type))
@@ -3886,23 +3899,6 @@ range_tests_floats ()
   r0.clear_nan ();
   ASSERT_FALSE (r0.varying_p ());
 
-  // The endpoints of a VARYING are +-INF.
-  r0.set_varying (float_type_node);
-  ASSERT_TRUE (real_identical (&r0.lower_bound (), &dconstninf));
-  ASSERT_TRUE (real_identical (&r0.upper_bound (), &dconstinf));
-
-  // The maximum representable range for a type is still a subset of VARYING.
-  REAL_VALUE_TYPE q, r;
-  real_min_representable (&q, float_type_node);
-  real_max_representable (&r, float_type_node);
-  r0 = frange (float_type_node, q, r);
-  // r0 is not a varying, because it does not include -INF/+INF.
-  ASSERT_FALSE (r0.varying_p ());
-  // The upper bound of r0 must be less than +INF.
-  ASSERT_TRUE (real_less (&r0.upper_bound (), &dconstinf));
-  // The lower bound of r0 must be greater than -INF.
-  ASSERT_TRUE (real_less (&dconstninf, &r0.lower_bound ()));
-
   // For most architectures, where float and double are different
   // sizes, having the same endpoints does not necessarily mean the
   // ranges are equal.
diff --git a/gcc/value-range.h b/gcc/value-range.h
index 3668b331187..413e54bda6f 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -593,6 +593,8 @@ extern void dump_value_range (FILE *, const vrange *);
 extern bool vrp_val_is_min (const_tree);
 extern bool vrp_val_is_max (const_tree);
 extern bool vrp_operand_equal_p (const_tree, const_tree);
+inline REAL_VALUE_TYPE frange_val_min (const_tree type);
+inline REAL_VALUE_TYPE frange_val_max (const_tree type);
 
 inline value_range_kind
 vrange::kind () const
@@ -1009,7 +1011,10 @@ vrp_val_max (const_tree type)
       return wide_int_to_tree (const_cast<tree> (type), max);
     }
   if (frange::supports_p (type))
-    return build_real (const_cast <tree> (type), dconstinf);
+    {
+      REAL_VALUE_TYPE r = frange_val_max (type);
+      return build_real (const_cast <tree> (type), r);
+    }
   return NULL_TREE;
 }
 
@@ -1023,7 +1028,10 @@ vrp_val_min (const_tree type)
   if (POINTER_TYPE_P (type))
     return build_zero_cst (const_cast<tree> (type));
   if (frange::supports_p (type))
-    return build_real (const_cast <tree> (type), dconstninf);
+    {
+      REAL_VALUE_TYPE r = frange_val_min (type);
+      return build_real (const_cast <tree> (type), r);
+    }
   return NULL_TREE;
 }
 
@@ -1073,8 +1081,8 @@ frange::set_varying (tree type)
 {
   m_kind = VR_VARYING;
   m_type = type;
-  m_min = dconstninf;
-  m_max = dconstinf;
+  m_min = frange_val_min (type);
+  m_max = frange_val_max (type);
   m_pos_nan = true;
   m_neg_nan = true;
 }
@@ -1132,23 +1140,66 @@ frange::clear_nan ()
 
 // Set R to maximum representable value for TYPE.
 
-inline void
-real_max_representable (REAL_VALUE_TYPE *r, tree type)
+inline REAL_VALUE_TYPE
+real_max_representable (const_tree type)
 {
+  REAL_VALUE_TYPE r;
   char buf[128];
   get_max_float (REAL_MODE_FORMAT (TYPE_MODE (type)),
 		 buf, sizeof (buf), false);
-  int res = real_from_string (r, buf);
+  int res = real_from_string (&r, buf);
   gcc_checking_assert (!res);
+  return r;
 }
 
-// Set R to minimum representable value for TYPE.
+// Return the minimum representable value for TYPE.
 
-inline void
-real_min_representable (REAL_VALUE_TYPE *r, tree type)
+inline REAL_VALUE_TYPE
+real_min_representable (const_tree type)
+{
+  REAL_VALUE_TYPE r = real_max_representable (type);
+  r = real_value_negate (&r);
+  return r;
+}
+
+// Return the minimum value for TYPE.
+
+inline REAL_VALUE_TYPE
+frange_val_min (const_tree type)
+{
+  if (flag_finite_math_only)
+    return real_min_representable (type);
+  else
+    return dconstninf;
+}
+
+// Return the maximum value for TYPE.
+
+inline REAL_VALUE_TYPE
+frange_val_max (const_tree type)
+{
+  if (flag_finite_math_only)
+    return real_max_representable (type);
+  else
+    return dconstinf;
+}
+
+// Return TRUE if R is the minimum value for TYPE.
+
+inline bool
+frange_val_is_min (const REAL_VALUE_TYPE &r, const_tree type)
+{
+  REAL_VALUE_TYPE min = frange_val_min (type);
+  return real_identical (&min, &r);
+}
+
+// Return TRUE if R is the max value for TYPE.
+
+inline bool
+frange_val_is_max (const REAL_VALUE_TYPE &r, const_tree type)
 {
-  real_max_representable (r, type);
-  *r = real_value_negate (r);
+  REAL_VALUE_TYPE max = frange_val_max (type);
+  return real_identical (&max, &r);
 }
 
 // Build a signless NAN of type TYPE.