From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: Fangrui Song <maskray@google.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH] x86: Remove .tfloat usage
Date: Mon, 3 Oct 2022 10:39:00 -0300 [thread overview]
Message-ID: <366379ec-34f4-e915-cdb0-0abc59ded57a@linaro.org> (raw)
In-Reply-To: <20220927081800.cneqysrxh7mt23sk@google.com>
On 27/09/22 05:18, Fangrui Song wrote:
> On 2022-09-26, Adhemerval Zanella via Libc-alpha wrote:
>> Some compiler does not support it (such as clang integrated assembly)
>> neither gcc emits it.
>
> assembler
Ack.
>
>> ---
>> sysdeps/i386/fpu/e_atanh.S | 3 ++-
>> sysdeps/i386/fpu/e_atanhf.S | 3 ++-
>> sysdeps/i386/fpu/e_atanhl.S | 3 ++-
>> sysdeps/i386/fpu/s_asinhl.S | 3 ++-
>> sysdeps/i386/fpu/s_cbrtl.S | 44 +++++++++++++++++++++--------------
>> sysdeps/i386/fpu/s_expm1.S | 3 ++-
>> sysdeps/i386/fpu/s_expm1f.S | 3 ++-
>> sysdeps/i386/fpu/s_log1pl.S | 3 ++-
>> sysdeps/x86_64/fpu/s_log1pl.S | 3 ++-
>> 9 files changed, 42 insertions(+), 26 deletions(-)
>>
>> diff --git a/sysdeps/i386/fpu/e_atanh.S b/sysdeps/i386/fpu/e_atanh.S
>> index 6e4fef06b2..a7fd9a60fa 100644
>> --- a/sysdeps/i386/fpu/e_atanh.S
>> +++ b/sysdeps/i386/fpu/e_atanh.S
>> @@ -33,7 +33,8 @@ one: .double 1.0
>> limit: .double 0.29
>> ASM_SIZE_DIRECTIVE(limit)
>> .type ln2_2,@object
>> -ln2_2: .tfloat 0.3465735902799726547086160
>> +ln2_2: .quad 0xb17217f7d1cf79ac /* 0.3465735902799726547086160L */
>> + .short 0x3ffd
>> ASM_SIZE_DIRECTIVE(ln2_2)
>
> There is one space before /* while the following uses two.
Ack.
>
> .tfloat output is 10 bytes without padding. .quad output is 8 bytes.
> Does this change semantics?
>
>> DEFINE_DBL_MIN
>> diff --git a/sysdeps/i386/fpu/e_atanhf.S b/sysdeps/i386/fpu/e_atanhf.S
>> index 146196eced..4ab1fa31fb 100644
>> --- a/sysdeps/i386/fpu/e_atanhf.S
>> +++ b/sysdeps/i386/fpu/e_atanhf.S
>> @@ -34,7 +34,8 @@ limit: .double 0.29
>> ASM_SIZE_DIRECTIVE(limit)
>> .align ALIGNARG(4)
>> .type ln2_2,@object
>> -ln2_2: .tfloat 0.3465735902799726547086160
>> +ln2_2: .quad 0xb17217f7d1cf79ac /* 0.3465735902799726547086160L */
>> + .short 0x3ffd
>> ASM_SIZE_DIRECTIVE(ln2_2)
>>
>> DEFINE_FLT_MIN
>> diff --git a/sysdeps/i386/fpu/e_atanhl.S b/sysdeps/i386/fpu/e_atanhl.S
>> index 1f6eb7ce48..df3f1b8f84 100644
>> --- a/sysdeps/i386/fpu/e_atanhl.S
>> +++ b/sysdeps/i386/fpu/e_atanhl.S
>> @@ -39,7 +39,8 @@ limit: .double 0.29
>> ASM_SIZE_DIRECTIVE(limit)
>> .align ALIGNARG(4)
>> .type ln2_2,@object
>> -ln2_2: .tfloat 0.3465735902799726547086160
>> +ln2_2: .quad 0xb17217f7d1cf79ac /* 0.3465735902799726547086160 */
>> + .short 0x3ffd
>> ASM_SIZE_DIRECTIVE(ln2_2)
>>
>> #ifdef PIC
>> diff --git a/sysdeps/i386/fpu/s_asinhl.S b/sysdeps/i386/fpu/s_asinhl.S
>> index bd442c6a09..f4f420d060 100644
>> --- a/sysdeps/i386/fpu/s_asinhl.S
>> +++ b/sysdeps/i386/fpu/s_asinhl.S
>> @@ -23,7 +23,8 @@
>>
>> .align ALIGNARG(4)
>> .type huge,@object
>> -huge: .tfloat 1e+4930
>> +huge: .quad 0x89b634e7456ffa1d /* 1e+4930 */
>> + .short 0x7ff8
>> ASM_SIZE_DIRECTIVE(huge)
>> .align ALIGNARG(4)
>> /* Please note that we use double value for 1.0. This number
>> diff --git a/sysdeps/i386/fpu/s_cbrtl.S b/sysdeps/i386/fpu/s_cbrtl.S
>> index 8802164706..935ac20530 100644
>> --- a/sysdeps/i386/fpu/s_cbrtl.S
>> +++ b/sysdeps/i386/fpu/s_cbrtl.S
>> @@ -23,55 +23,63 @@
>>
>> .align ALIGNARG(4)
>> .type f8,@object
>> -f8: .tfloat 0.161617097923756032
>> +f8: .quad 0xa57ef3d83a542839 /* 0.161617097923756032 */
>> + .short 0x3ffc
>> ASM_SIZE_DIRECTIVE(f8)
>> .align ALIGNARG(4)
>> .type f7,@object
>> -f7: .tfloat -0.988553671195413709
>> +f7: .quad 0xfd11da7820029014 /* -0.988553671195413709 */
>> + .short 0xbffe
>> ASM_SIZE_DIRECTIVE(f7)
>> .align ALIGNARG(4)
>> .type f6,@object
>> -f6: .tfloat 2.65298938441952296
>> +f6: .quad 0xa9ca93fcade3b4ad /* 2.65298938441952296 */
>> + .short 0x4000
>> ASM_SIZE_DIRECTIVE(f6)
>> .align ALIGNARG(4)
>> .type f5,@object
>> -f5: .tfloat -4.11151425200350531
>> +f5: .quad 0x839186562c931c34 /* -4.11151425200350531 */
>> + .short 0xc001
>> ASM_SIZE_DIRECTIVE(f5)
>> .align ALIGNARG(4)
>> .type f4,@object
>> -f4: .tfloat 4.09559907378707839
>> +f4: .quad 0x830f25c9ee304594 /* 4.09559907378707839 */
>> + .short 0x4001
>> ASM_SIZE_DIRECTIVE(f4)
>> .align ALIGNARG(4)
>> .type f3,@object
>> -f3: .tfloat -2.82414939754975962
>> +f3: .quad 0xb4bedd1d5fa2f0c6 /* -2.82414939754975962 */
>> + .short 0xc000
>> ASM_SIZE_DIRECTIVE(f3)
>> .align ALIGNARG(4)
>> .type f2,@object
>> -f2: .tfloat 1.67595307700780102
>> +f2: .quad 0xd685a163b08586e3 /* 1.67595307700780102 */
>> + .short 0x3fff
>> ASM_SIZE_DIRECTIVE(f2)
>> .align ALIGNARG(4)
>> .type f1,@object
>> -f1: .tfloat 0.338058687610520237
>> +f1: .quad 0xad16073ed4ec3b45 /* 0.338058687610520237 */
>> + .short 0x3ffd
>> ASM_SIZE_DIRECTIVE(f1)
>>
>> -#define CBRT2 1.2599210498948731648
>> -#define ONE_CBRT2 0.793700525984099737355196796584
>> -#define SQR_CBRT2 1.5874010519681994748
>> -#define ONE_SQR_CBRT2 0.629960524947436582364439673883
>> -
>> /* We make the entries in the following table all 16 bytes
>> wide to avoid having to implement a multiplication by 10. */
>> .type factor,@object
>> .align ALIGNARG(4)
>> -factor: .tfloat ONE_SQR_CBRT2
>> +factor: .quad 0xa14517cc6b945711 /* 0.629960524947436582364439673883L */
>> + .short 0x3ffe
>
> Perhaps keep the macro name in the comment for readability.
I am not sure if this make sense, since it will require to define the
macros using hexadecimal. I will add a comment instead with what the
values represent.
>
>> .byte 0, 0, 0, 0, 0, 0
>> - .tfloat ONE_CBRT2
>> + .quad 0xcb2ff529eb71e415 /* 1.5874010519681994748L */
>> + .short 0x3ffe
>> .byte 0, 0, 0, 0, 0, 0
>> - .tfloat 1.0
>> + .quad 0x8000000000000000 /* 1.0L */
>> + .short 0x3fff
>> .byte 0, 0, 0, 0, 0, 0
>> - .tfloat CBRT2
>> + .quad 0xa14517cc6b945711 /* 1.2599210498948731648L */
>> + .short 0x3fff
>> .byte 0, 0, 0, 0, 0, 0
>> - .tfloat SQR_CBRT2
>> + .quad 0xcb2ff529eb71e416 /* 1.5874010519681994748L */
>> + .short 0x3fff
>> ASM_SIZE_DIRECTIVE(factor)
>>
>> .type two64,@object
>> diff --git a/sysdeps/i386/fpu/s_expm1.S b/sysdeps/i386/fpu/s_expm1.S
>> index 7199d681ba..038ff72feb 100644
>> --- a/sysdeps/i386/fpu/s_expm1.S
>> +++ b/sysdeps/i386/fpu/s_expm1.S
>> @@ -33,7 +33,8 @@ minus1: .double -1.0
>> one: .double 1.0
>> ASM_SIZE_DIRECTIVE(one)
>> .type l2e,@object
>> -l2e: .tfloat 1.442695040888963407359924681002
>> +l2e: .quad 0xb8aa3b295c17f0bc /* 1.442695040888963407359924681002 */
>> + .short 0x3fff
>> ASM_SIZE_DIRECTIVE(l2e)
>>
>> DEFINE_DBL_MIN
>> diff --git a/sysdeps/i386/fpu/s_expm1f.S b/sysdeps/i386/fpu/s_expm1f.S
>> index 04c37bda1b..b0406a45aa 100644
>> --- a/sysdeps/i386/fpu/s_expm1f.S
>> +++ b/sysdeps/i386/fpu/s_expm1f.S
>> @@ -33,7 +33,8 @@ minus1: .double -1.0
>> one: .double 1.0
>> ASM_SIZE_DIRECTIVE(one)
>> .type l2e,@object
>> -l2e: .tfloat 1.442695040888963407359924681002
>> +l2e: .quad 0xb8aa3b295c17f0bc /* 1.442695040888963407359924681002 */
>> + .short 0x3fff
>> ASM_SIZE_DIRECTIVE(l2e)
>>
>> DEFINE_FLT_MIN
>> diff --git a/sysdeps/i386/fpu/s_log1pl.S b/sysdeps/i386/fpu/s_log1pl.S
>> index f28349f7d2..202995d3d6 100644
>> --- a/sysdeps/i386/fpu/s_log1pl.S
>> +++ b/sysdeps/i386/fpu/s_log1pl.S
>> @@ -14,7 +14,8 @@ RCSID("$NetBSD: s_log1p.S,v 1.7 1995/05/09 00:10:58 jtc Exp $")
>> -1 + sqrt(2) / 2 <= x <= 1 - sqrt(2) / 2
>> 0.29 is a safe value.
>> */
>> -limit: .tfloat 0.29
>> +limit: .quad 0x947ae147ae147ae1 /* 0.29 */
>> + .short 0x3ffd
>
> Inconsistent use of L suffixes.
>
>> /* Please note: we use a double value here. Since 1.0 has
>> an exact representation this does not effect the accuracy
>> but it helps to optimize the code. */
>> diff --git a/sysdeps/x86_64/fpu/s_log1pl.S b/sysdeps/x86_64/fpu/s_log1pl.S
>> index 8219f6fbcc..b053579dc5 100644
>> --- a/sysdeps/x86_64/fpu/s_log1pl.S
>> +++ b/sysdeps/x86_64/fpu/s_log1pl.S
>> @@ -14,7 +14,8 @@ RCSID("$NetBSD: s_log1p.S,v 1.7 1995/05/09 00:10:58 jtc Exp $")
>> -1 + sqrt(2) / 2 <= x <= 1 - sqrt(2) / 2
>> 0.29 is a safe value.
>> */
>> -limit: .tfloat 0.29
>> +limit: .quad 0x947ae147ae147ae1 /* 0.29L */
>> + .short 0x3ffd
>> /* Please note: we use a double value here. Since 1.0 has
>> an exact representation this does not effect the accuracy
>> but it helps to optimize the code. */
>> --
>> 2.34.1
>>
prev parent reply other threads:[~2022-10-03 13:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-26 16:53 Adhemerval Zanella
2022-09-26 19:00 ` Noah Goldstein
2022-09-27 19:46 ` H.J. Lu
2022-09-27 8:18 ` Fangrui Song
2022-09-27 8:19 ` Fangrui Song
2022-09-27 19:44 ` H.J. Lu
2022-10-03 13:39 ` Adhemerval Zanella Netto [this message]
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