Provide cleaner set_nan(), clear_nan(), and update_nan() methods.

set_* has a very specific meaning for irange's and friends.  Methods
prefixed with set_* are setters clobbering the existing range.  As
such, the current set_nan() method is confusing in that it's not
actually setting a range to a NAN, but twiddling the NAN flags for an
existing frange.

This patch replaces set_nan() with an update_nan() to set the flag,
and clear_nan() to clear it.  This makes the code clearer, and though
the confusing tristate is still there, it will be removed in upcoming
patches.

Also, there is now an actual set_nan() method to set the range to a
NAN.  This replaces two out of class functions doing the same thing.
In future patches I will also add the ability to create a NAN with a
specific sign, but doing so now would be confusing because we're not
tracking NAN signs.

We should also submit set_signbit to the same fate, but it's about to
get removed.

No functional changes.

Regstrapped on x86-64 Linux, plus I ran selftests for
-ffinite-math-only.

gcc/ChangeLog:

	* range-op-float.cc (frange_set_nan): Remove.
	(build_lt): Use set_nan, update_nan, clear_nan.
	(build_gt): Same.
	(foperator_equal::op1_range): Same.
	(foperator_not_equal::op1_range): Same.
	(foperator_lt::op1_range): Same.
	(foperator_lt::op2_range): Same.
	(foperator_le::op1_range): Same.
	(foperator_le::op2_range): Same.
	(foperator_gt::op1_range): Same.
	(foperator_gt::op2_range): Same.
	(foperator_ge::op1_range): Same.
	(foperator_ge::op2_range): Same.
	(foperator_unordered::op1_range): Same.
	(foperator_ordered::op1_range): Same.
	* value-query.cc (range_query::get_tree_range): Same.
	* value-range.cc (frange::set_nan): Same.
	(frange::update_nan): Same.
	(frange::union_): Same.
	(frange::intersect): Same.
	(range_tests_nan): Same.
	(range_tests_signed_zeros): Same.
	(range_tests_signbit): Same.
	(range_tests_floats): Same.
	* value-range.h (class frange): Add update_nan and clear_nan.
	(frange::set_nan): New.

1 files changed, 6 insertions, 5 deletions

diff --git a/gcc/value-range.h b/gcc/value-range.h
index 0ba0193..6e896eb 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -348,6 +348,7 @@ public:
   virtual void set (tree, tree, value_range_kind = VR_RANGE) override;
   void set (tree type, const REAL_VALUE_TYPE &, const REAL_VALUE_TYPE &,
 	    value_range_kind = VR_RANGE);
+  void set_nan (tree type);
   virtual void set_varying (tree type) override;
   virtual void set_undefined () override;
   virtual bool union_ (const vrange &) override;
@@ -376,7 +377,8 @@ public:
   bool known_signbit (bool &signbit) const;
 
   // Accessors for FP properties.
-  void set_nan (fp_prop::kind f);
+  void update_nan (fp_prop::kind f);
+  void clear_nan () { update_nan (fp_prop::NO); }
   void set_signbit (fp_prop::kind);
 private:
   fp_prop get_nan () const { return m_props.get_nan (); }
@@ -1186,13 +1188,12 @@ real_min_representable (REAL_VALUE_TYPE *r, tree type)
 
 // Build a NAN of type TYPE.
 
-inline frange
-frange_nan (tree type)
+inline void
+frange::set_nan (tree type)
 {
   REAL_VALUE_TYPE r;
-
   gcc_assert (real_nan (&r, "", 1, TYPE_MODE (type)));
-  return frange (type, r, r);
+  set (type, r, r);
 }
 
 // Return TRUE if range is known to be finite.