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Provide normalized and denormal format version of real_isdenormal.

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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.
This commit is contained in:
Aldy Hernandez 2022-11-07 14:18:57 +01:00
parent 7899582a05
commit 3e0ab430c0
3 changed files with 23 additions and 17 deletions
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28
gcc/real.cc
View file

@ -111,6 +111,16 @@ static const REAL_VALUE_TYPE * real_digit (int);
static void times_pten (REAL_VALUE_TYPE *, int);
static void round_for_format (const struct real_format *, REAL_VALUE_TYPE *);
/* Determine whether a floating-point value X is a denormal. R is
expected to be in denormal form, so this function is only
meaningful after a call to round_for_format. */
static inline bool
real_isdenormal (const REAL_VALUE_TYPE *r)
{
return r->cl == rvc_normal && (r->sig[SIGSZ-1] & SIG_MSB) == 0;
}
/* Initialize R with a positive zero. */
@ -2962,7 +2972,6 @@ encode_ieee_single (const struct real_format *fmt, long *buf,
{
unsigned long image, sig, exp;
unsigned long sign = r->sign;
bool denormal = real_isdenormal (r);
image = sign << 31;
sig = (r->sig[SIGSZ-1] >> (HOST_BITS_PER_LONG - 24)) & 0x7fffff;
@ -3002,7 +3011,7 @@ encode_ieee_single (const struct real_format *fmt, long *buf,
/* Recall that IEEE numbers are interpreted as 1.F x 2**exp,
whereas the intermediate representation is 0.F x 2**exp.
Which means we're off by one. */
if (denormal)
if (real_isdenormal (r))
exp = 0;
else
exp = REAL_EXP (r) + 127 - 1;
@ -3183,7 +3192,6 @@ encode_ieee_double (const struct real_format *fmt, long *buf,
{
unsigned long image_lo, image_hi, sig_lo, sig_hi, exp;
unsigned long sign = r->sign;
bool denormal = real_isdenormal (r);
image_hi = sign << 31;
image_lo = 0;
@ -3255,7 +3263,7 @@ encode_ieee_double (const struct real_format *fmt, long *buf,
/* Recall that IEEE numbers are interpreted as 1.F x 2**exp,
whereas the intermediate representation is 0.F x 2**exp.
Which means we're off by one. */
if (denormal)
if (real_isdenormal (r))
exp = 0;
else
exp = REAL_EXP (r) + 1023 - 1;
@ -3441,7 +3449,6 @@ encode_ieee_extended (const struct real_format *fmt, long *buf,
const REAL_VALUE_TYPE *r)
{
unsigned long image_hi, sig_hi, sig_lo;
bool denormal = real_isdenormal (r);
image_hi = r->sign << 15;
sig_hi = sig_lo = 0;
@ -3523,7 +3530,7 @@ encode_ieee_extended (const struct real_format *fmt, long *buf,
this discrepancy has been taken care of by the difference
in fmt->emin in round_for_format. */
if (denormal)
if (real_isdenormal (r))
exp = 0;
else
{
@ -3972,7 +3979,6 @@ encode_ieee_quad (const struct real_format *fmt, long *buf,
{
unsigned long image3, image2, image1, image0, exp;
unsigned long sign = r->sign;
bool denormal = real_isdenormal (r);
REAL_VALUE_TYPE u;
image3 = sign << 31;
@ -4048,7 +4054,7 @@ encode_ieee_quad (const struct real_format *fmt, long *buf,
/* Recall that IEEE numbers are interpreted as 1.F x 2**exp,
whereas the intermediate representation is 0.F x 2**exp.
Which means we're off by one. */
if (denormal)
if (real_isdenormal (r))
exp = 0;
else
exp = REAL_EXP (r) + 16383 - 1;
@ -4729,7 +4735,6 @@ encode_ieee_half (const struct real_format *fmt, long *buf,
{
unsigned long image, sig, exp;
unsigned long sign = r->sign;
bool denormal = real_isdenormal (r);
image = sign << 15;
sig = (r->sig[SIGSZ-1] >> (HOST_BITS_PER_LONG - 11)) & 0x3ff;
@ -4769,7 +4774,7 @@ encode_ieee_half (const struct real_format *fmt, long *buf,
/* Recall that IEEE numbers are interpreted as 1.F x 2**exp,
whereas the intermediate representation is 0.F x 2**exp.
Which means we're off by one. */
if (denormal)
if (real_isdenormal (r))
exp = 0;
else
exp = REAL_EXP (r) + 15 - 1;
@ -4843,7 +4848,6 @@ encode_arm_bfloat_half (const struct real_format *fmt, long *buf,
{
unsigned long image, sig, exp;
unsigned long sign = r->sign;
bool denormal = real_isdenormal (r);
image = sign << 15;
sig = (r->sig[SIGSZ-1] >> (HOST_BITS_PER_LONG - 8)) & 0x7f;
@ -4880,7 +4884,7 @@ encode_arm_bfloat_half (const struct real_format *fmt, long *buf,
break;
case rvc_normal:
if (denormal)
if (real_isdenormal (r))
exp = 0;
else
exp = REAL_EXP (r) + 127 - 1;

7
gcc/real.h
View file

@ -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. */

5
gcc/value-range.cc
View file

@ -266,15 +266,16 @@ frange::flush_denormals_to_zero ()
if (undefined_p () || known_isnan ())
return;
machine_mode mode = TYPE_MODE (type ());
// Flush [x, -DENORMAL] to [x, -0.0].
if (real_isdenormal (&m_max) && real_isneg (&m_max))
if (real_isdenormal (&m_max, mode) && real_isneg (&m_max))
{
m_max = dconst0;
if (HONOR_SIGNED_ZEROS (m_type))
m_max.sign = 1;
}
// Flush [+DENORMAL, x] to [+0.0, x].
if (real_isdenormal (&m_min) && !real_isneg (&m_min))
if (real_isdenormal (&m_min, mode) && !real_isneg (&m_min))
m_min = dconst0;
}