Declare dconstm0 to go along with dconst0 and friends.

Negating dconst0 is getting pretty old, and we will keep adding copies
of the same idiom.  Fixed by adding a dconstm0 constant to go along
with dconst1, dconstm1, etc.

gcc/ChangeLog:

	* emit-rtl.cc (init_emit_once): Initialize dconstm0.
	* gimple-range-op.cc (class cfn_signbit): Remove dconstm0
	declaration.
	* range-op-float.cc (zero_range): Use dconstm0.
	(zero_to_inf_range): Same.
	* real.h (dconstm0): New.
	* value-range.cc (frange::flush_denormals_to_zero): Use dconstm0.
	(frange::set_zero): Do not declare dconstm0.

1 files changed, 3 insertions, 4 deletions

diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 8b5d0cb..3b3102b 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -322,9 +322,10 @@ frange::flush_denormals_to_zero ()
   // Flush [x, -DENORMAL] to [x, -0.0].
   if (real_isdenormal (&m_max, mode) && real_isneg (&m_max))
     {
-      m_max = dconst0;
       if (HONOR_SIGNED_ZEROS (m_type))
-	m_max.sign = 1;
+	m_max = dconstm0;
+      else
+	m_max = dconst0;
     }
   // Flush [+DENORMAL, x] to [+0.0, x].
   if (real_isdenormal (&m_min, mode) && !real_isneg (&m_min))
@@ -837,8 +838,6 @@ frange::set_zero (tree type)
 {
   if (HONOR_SIGNED_ZEROS (type))
     {
-      REAL_VALUE_TYPE dconstm0 = dconst0;
-      dconstm0.sign = 1;
       set (type, dconstm0, dconst0);
       clear_nan ();
     }