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Re: [PATCH v3] Enable inlining issignalingf within glibc (was "v2")
- From: Paul Clarke <pc at us dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Cc: joseph at codesourcery dot com
- Date: Wed, 16 Oct 2019 11:50:27 -0500
- Subject: Re: [PATCH v3] Enable inlining issignalingf within glibc (was "v2")
- References: <1569851517-5682-1-git-send-email-pc@us.ibm.com> <71995c1e-b84c-3980-2a7a-b586e32d01c8@us.ibm.com>
ping.
On 9/30/19 10:19 AM, Paul Clarke wrote:
> Sorry, this should've been noted as "v3". ugh
>
> On 9/30/19 8:51 AM, Paul A. Clarke wrote:
>> From: "Paul A. Clarke" <pc@us.ibm.com>
>>
>> issignalingf is a very small function used in some areas where
>> better performance (and smaller code) might be helpful.
>>
>> Create inline implementation for issignalingf.
>>
>> 2019-09-30 Paul A. Clarke <pc@us.ibm.com>
>>
>> * sysdeps/generic/math_private.h (GET_FLOAT_WORD, SET_FLOAT_WORD):
>> Moved...
>> * include/math.h (GET_FLOAT_WORD, SET_FLOAT_WORD): to here.
>> (__issignalingf): New, copied from
>> sysdeps/iee754/flt-32/s_issignalingf.c.
>> ---
>> v2:
>> - New approach as suggested by Joseph Myers: no implementations in
>> math_private.h, instead in include/math.h.
>> - Moved GET_FLOAT_WORD from math_private.h to include/math.h in support.
>> - Brought along matching SET_FLOAT_WORD for consistency.
>>
>> include/math.h | 53 ++++++++++++++++++++++++++++++++++++++++++
>> sysdeps/generic/math_private.h | 29 -----------------------
>> 2 files changed, 53 insertions(+), 29 deletions(-)
>>
>> diff --git a/include/math.h b/include/math.h
>> index 79ebbae..a274f2b 100644
>> --- a/include/math.h
>> +++ b/include/math.h
>> @@ -54,6 +54,59 @@ libm_hidden_proto (__expf128)
>> libm_hidden_proto (__expm1f128)
>> # endif
>>
>> +#include <stdint.h>
>> +#include <nan-high-order-bit.h>
>> +
>> +/* A union which permits us to convert between a float and a 32 bit
>> + int. */
>> +
>> +typedef union
>> +{
>> + float value;
>> + uint32_t word;
>> +} ieee_float_shape_type;
>> +
>> +/* Get a 32 bit int from a float. */
>> +#ifndef GET_FLOAT_WORD
>> +# define GET_FLOAT_WORD(i,d) \
>> +do { \
>> + ieee_float_shape_type gf_u; \
>> + gf_u.value = (d); \
>> + (i) = gf_u.word; \
>> +} while (0)
>> +#endif
>> +
>> +/* Set a float from a 32 bit int. */
>> +#ifndef SET_FLOAT_WORD
>> +# define SET_FLOAT_WORD(d,i) \
>> +do { \
>> + ieee_float_shape_type sf_u; \
>> + sf_u.word = (i); \
>> + (d) = sf_u.value; \
>> +} while (0)
>> +#endif
>> +
>> +extern inline int
>> +__issignalingf (float x)
>> +{
>> + uint32_t xi;
>> + GET_FLOAT_WORD (xi, x);
>> +#if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
>> + /* We only have to care about the high-order bit of x's significand, because
>> + having it set (sNaN) already makes the significand different from that
>> + used to designate infinity. */
>> + return (xi & 0x7fc00000) == 0x7fc00000;
>> +#else
>> + /* To keep the following comparison simple, toggle the quiet/signaling bit,
>> + so that it is set for sNaNs. This is inverse to IEEE 754-2008 (as well as
>> + common practice for IEEE 754-1985). */
>> + xi ^= 0x00400000;
>> + /* We have to compare for greater (instead of greater or equal), because x's
>> + significand being all-zero designates infinity not NaN. */
>> + return (xi & 0x7fffffff) > 0x7fc00000;
>> +#endif
>> +}
>> +
>> # if __HAVE_DISTINCT_FLOAT128
>>
>> /* __builtin_isinf_sign is broken in GCC < 7 for float128. */
>> diff --git a/sysdeps/generic/math_private.h b/sysdeps/generic/math_private.h
>> index d91b929..9296324 100644
>> --- a/sysdeps/generic/math_private.h
>> +++ b/sysdeps/generic/math_private.h
>> @@ -153,35 +153,6 @@ do { \
>> } while (0)
>> #endif
>>
>> -/* A union which permits us to convert between a float and a 32 bit
>> - int. */
>> -
>> -typedef union
>> -{
>> - float value;
>> - uint32_t word;
>> -} ieee_float_shape_type;
>> -
>> -/* Get a 32 bit int from a float. */
>> -#ifndef GET_FLOAT_WORD
>> -# define GET_FLOAT_WORD(i,d) \
>> -do { \
>> - ieee_float_shape_type gf_u; \
>> - gf_u.value = (d); \
>> - (i) = gf_u.word; \
>> -} while (0)
>> -#endif
>> -
>> -/* Set a float from a 32 bit int. */
>> -#ifndef SET_FLOAT_WORD
>> -# define SET_FLOAT_WORD(d,i) \
>> -do { \
>> - ieee_float_shape_type sf_u; \
>> - sf_u.word = (i); \
>> - (d) = sf_u.value; \
>> -} while (0)
>> -#endif
>> -
>> /* We need to guarantee an expansion of name when building
>> ldbl-128 files as another type (e.g _Float128). */
>> #define mathx_hidden_def(name) hidden_def(name)
>>
> PC
>