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, 3 deletions

diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index e0e91ba..9d18461 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -2263,7 +2263,7 @@ zero_range (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, int signbit_known)
 {
   ub = lb = dconst0;
   if (signbit_known <= 0)
-    lb = real_value_negate (&dconst0);
+    lb = dconstm0;
   if (signbit_known < 0)
     ub = lb;
 }
@@ -2297,7 +2297,7 @@ zero_to_inf_range (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, int signbit_known)
   else if (signbit_known < 0)
     {
       lb = dconstninf;
-      ub = real_value_negate (&dconst0);
+      ub = dconstm0;
     }
   else
     {
@@ -2634,7 +2634,7 @@ private:
 	    if (real_isneg (&lh_lb) == real_isneg (&lh_ub))
 	      cp[1] = dconst0;
 	    else
-	      cp[1] = real_value_negate (&dconst0);
+	      cp[1] = dconstm0;
 	  }
 	else
 	  cp[1] = cp[0];