Provide normalized and denormal format version of real_isdenormal.

Implement a variant of real_isdenormal() to be used within real.cc
where the argument is known to be in denormal format.  Rewrite
real_isdenormal() for use outside of real.cc where the argument is
known to be normalized.

gcc/ChangeLog:

	* real.cc (real_isdenormal): New.
	(encode_ieee_single): Call real_isdenormal.
	(encode_ieee_double): Same.
	(encode_ieee_extended): Same.
	(encode_ieee_quad): Same.
	(encode_ieee_half): Same.
	(encode_arm_bfloat_half): Same.
	* real.h (real_isdenormal): Add mode argument.  Rewrite for
	normalized values.
	* value-range.cc (frange::flush_denormals_to_zero): Pass mode to
	real_isdenormal.

1 files changed, 4 insertions, 3 deletions

diff --git a/gcc/real.h b/gcc/real.h
index 306e959..b14bcdd 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -286,11 +286,12 @@ extern bool real_isnan (const REAL_VALUE_TYPE *);
 /* Determine whether a floating-point value X is a signaling NaN.  */
 extern bool real_issignaling_nan (const REAL_VALUE_TYPE *);
 
-/* Determine whether a floating-point value X is a denormal.  */
+/* Determine whether floating-point value R is a denormal.  This
+   function is only valid for normalized values.  */
 inline bool
-real_isdenormal (const REAL_VALUE_TYPE *r)
+real_isdenormal (const REAL_VALUE_TYPE *r, machine_mode mode)
 {
-  return r->cl == rvc_normal && (r->sig[SIGSZ-1] & SIG_MSB) == 0;
+  return r->cl == rvc_normal && REAL_EXP (r) < REAL_MODE_FORMAT (mode)->emin;
 }
 
 /* Determine whether a floating-point value X is finite.  */