* [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint
@ 2022-04-11 1:09 Noah Goldstein
2022-04-11 1:09 ` [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64 Noah Goldstein
2022-04-14 22:21 ` [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint Joseph Myers
0 siblings, 2 replies; 7+ messages in thread
From: Noah Goldstein @ 2022-04-11 1:09 UTC (permalink / raw)
To: libc-alpha
The goal is to make it easier to provide system specific defs for the
sizes of {u}int_fast{8|16|32|64}.
Note this commit does not change any of the previous values.
Full xcheck passes on x86_64.
---
stdlib/stdint.h | 70 +-----------------------
sysdeps/generic/int-fast.h | 107 +++++++++++++++++++++++++++++++++++++
2 files changed, 108 insertions(+), 69 deletions(-)
create mode 100644 sysdeps/generic/int-fast.h
diff --git a/stdlib/stdint.h b/stdlib/stdint.h
index 2d666f79fd..00f41e9ffb 100644
--- a/stdlib/stdint.h
+++ b/stdlib/stdint.h
@@ -52,35 +52,6 @@ typedef __uint_least32_t uint_least32_t;
typedef __uint_least64_t uint_least64_t;
-/* Fast types. */
-
-/* Signed. */
-typedef signed char int_fast8_t;
-#if __WORDSIZE == 64
-typedef long int int_fast16_t;
-typedef long int int_fast32_t;
-typedef long int int_fast64_t;
-#else
-typedef int int_fast16_t;
-typedef int int_fast32_t;
-__extension__
-typedef long long int int_fast64_t;
-#endif
-
-/* Unsigned. */
-typedef unsigned char uint_fast8_t;
-#if __WORDSIZE == 64
-typedef unsigned long int uint_fast16_t;
-typedef unsigned long int uint_fast32_t;
-typedef unsigned long int uint_fast64_t;
-#else
-typedef unsigned int uint_fast16_t;
-typedef unsigned int uint_fast32_t;
-__extension__
-typedef unsigned long long int uint_fast64_t;
-#endif
-
-
/* Types for `void *' pointers. */
#if __WORDSIZE == 64
# ifndef __intptr_t_defined
@@ -148,37 +119,7 @@ typedef __uintmax_t uintmax_t;
# define UINT_LEAST64_MAX (__UINT64_C(18446744073709551615))
-/* Minimum of fast signed integral types having a minimum size. */
-# define INT_FAST8_MIN (-128)
-# if __WORDSIZE == 64
-# define INT_FAST16_MIN (-9223372036854775807L-1)
-# define INT_FAST32_MIN (-9223372036854775807L-1)
-# else
-# define INT_FAST16_MIN (-2147483647-1)
-# define INT_FAST32_MIN (-2147483647-1)
-# endif
-# define INT_FAST64_MIN (-__INT64_C(9223372036854775807)-1)
-/* Maximum of fast signed integral types having a minimum size. */
-# define INT_FAST8_MAX (127)
-# if __WORDSIZE == 64
-# define INT_FAST16_MAX (9223372036854775807L)
-# define INT_FAST32_MAX (9223372036854775807L)
-# else
-# define INT_FAST16_MAX (2147483647)
-# define INT_FAST32_MAX (2147483647)
-# endif
-# define INT_FAST64_MAX (__INT64_C(9223372036854775807))
-
-/* Maximum of fast unsigned integral types having a minimum size. */
-# define UINT_FAST8_MAX (255)
-# if __WORDSIZE == 64
-# define UINT_FAST16_MAX (18446744073709551615UL)
-# define UINT_FAST32_MAX (18446744073709551615UL)
-# else
-# define UINT_FAST16_MAX (4294967295U)
-# define UINT_FAST32_MAX (4294967295U)
-# endif
-# define UINT_FAST64_MAX (__UINT64_C(18446744073709551615))
+#include <int-fast.h>
/* Values to test for integral types holding `void *' pointer. */
@@ -293,15 +234,6 @@ typedef __uintmax_t uintmax_t;
# define INT_LEAST64_WIDTH 64
# define UINT_LEAST64_WIDTH 64
-# define INT_FAST8_WIDTH 8
-# define UINT_FAST8_WIDTH 8
-# define INT_FAST16_WIDTH __WORDSIZE
-# define UINT_FAST16_WIDTH __WORDSIZE
-# define INT_FAST32_WIDTH __WORDSIZE
-# define UINT_FAST32_WIDTH __WORDSIZE
-# define INT_FAST64_WIDTH 64
-# define UINT_FAST64_WIDTH 64
-
# define INTPTR_WIDTH __WORDSIZE
# define UINTPTR_WIDTH __WORDSIZE
diff --git a/sysdeps/generic/int-fast.h b/sysdeps/generic/int-fast.h
new file mode 100644
index 0000000000..554593d393
--- /dev/null
+++ b/sysdeps/generic/int-fast.h
@@ -0,0 +1,107 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#ifndef _INT_FAST_H
+#define _INT_FAST_H 1
+
+#define __PRIMITIVE_INT_FAST_CAT(X, Y) X##Y
+#define __INT_FAST_CAT(X, Y) __PRIMITIVE_INT_FAST_CAT (X, Y)
+
+#ifndef __HAS_INT_FAST_DEFS
+
+
+/* Fast types. */
+
+/* Signed. */
+typedef signed char int_fast8_t;
+#if __WORDSIZE == 64
+typedef long int int_fast16_t;
+typedef long int int_fast32_t;
+typedef long int int_fast64_t;
+#else
+typedef int int_fast16_t;
+typedef int int_fast32_t;
+__extension__
+typedef long long int int_fast64_t;
+#endif
+
+/* Unsigned. */
+typedef unsigned char uint_fast8_t;
+#if __WORDSIZE == 64
+typedef unsigned long int uint_fast16_t;
+typedef unsigned long int uint_fast32_t;
+typedef unsigned long int uint_fast64_t;
+#else
+typedef unsigned int uint_fast16_t;
+typedef unsigned int uint_fast32_t;
+__extension__
+typedef unsigned long long int uint_fast64_t;
+#endif
+
+/* Base types for INT_FAST{SIZE}. */
+# define __INT_FAST8_BASE INT8
+# if __WORDSIZE == 64
+# define __INT_FAST16_BASE INT64
+# define __INT_FAST32_BASE INT64
+# else
+# define __INT_FAST16_BASE INT32
+# define __INT_FAST32_BASE INT32
+# endif
+# define __INT_FAST64_BASE INT64
+
+# define __UINT_FAST8_BASE UINT8
+# if __WORDSIZE == 64
+# define __UINT_FAST16_BASE UINT64
+# define __UINT_FAST32_BASE UINT64
+# else
+# define __UINT_FAST16_BASE UINT32
+# define __UINT_FAST32_BASE UINT32
+# endif
+# define __UINT_FAST64_BASE UINT64
+
+#endif
+
+/* Minimum of fast signed integral types having a minimum size. */
+#define INT_FAST8_MIN __INT_FAST_CAT (__INT_FAST8_BASE, _MIN)
+#define INT_FAST16_MIN __INT_FAST_CAT (__INT_FAST16_BASE, _MIN)
+#define INT_FAST32_MIN __INT_FAST_CAT (__INT_FAST32_BASE, _MIN)
+#define INT_FAST64_MIN __INT_FAST_CAT (__INT_FAST64_BASE, _MIN)
+
+/* Maximum of fast signed integral types having a minimum size. */
+#define INT_FAST8_MAX __INT_FAST_CAT (__INT_FAST8_BASE, _MAX)
+#define INT_FAST16_MAX __INT_FAST_CAT (__INT_FAST16_BASE, _MAX)
+#define INT_FAST32_MAX __INT_FAST_CAT (__INT_FAST32_BASE, _MAX)
+#define INT_FAST64_MAX __INT_FAST_CAT (__INT_FAST64_BASE, _MAX)
+
+/* Maximum of fast unsigned integral types having a minimum size. */
+#define UINT_FAST8_MAX __INT_FAST_CAT (__UINT_FAST8_BASE, _MAX)
+#define UINT_FAST16_MAX __INT_FAST_CAT (__UINT_FAST16_BASE, _MAX)
+#define UINT_FAST32_MAX __INT_FAST_CAT (__UINT_FAST32_BASE, _MAX)
+#define UINT_FAST64_MAX __INT_FAST_CAT (__UINT_FAST64_BASE, _MAX)
+
+
+#define INT_FAST8_WIDTH __INT_FAST_CAT (__INT_FAST8_BASE, _WIDTH)
+#define INT_FAST16_WIDTH __INT_FAST_CAT (__INT_FAST16_BASE, _WIDTH)
+#define INT_FAST32_WIDTH __INT_FAST_CAT (__INT_FAST32_BASE, _WIDTH)
+#define INT_FAST64_WIDTH __INT_FAST_CAT (__INT_FAST64_BASE, _WIDTH)
+
+#define UINT_FAST8_WIDTH __INT_FAST_CAT (__UINT_FAST8_BASE, _WIDTH)
+#define UINT_FAST16_WIDTH __INT_FAST_CAT (__UINT_FAST16_BASE, _WIDTH)
+#define UINT_FAST32_WIDTH __INT_FAST_CAT (__UINT_FAST32_BASE, _WIDTH)
+#define UINT_FAST64_WIDTH __INT_FAST_CAT (__UINT_FAST64_BASE, _WIDTH)
+
+#endif
--
2.25.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64
2022-04-11 1:09 [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint Noah Goldstein
@ 2022-04-11 1:09 ` Noah Goldstein
2022-04-11 2:15 ` Adam Sampson
2022-04-14 22:24 ` Joseph Myers
2022-04-14 22:21 ` [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint Joseph Myers
1 sibling, 2 replies; 7+ messages in thread
From: Noah Goldstein @ 2022-04-11 1:09 UTC (permalink / raw)
To: libc-alpha
{u}int_fast{16|32} should never use 64-bit types. 64-bit instructions
often use more code size (REX prefix) and a variety of instructions are
slower on many implementations (div, bswap, etc...).
Full xcheck passes on x86_64.
---
sysdeps/x86_64/int-fast.h | 50 +++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
create mode 100644 sysdeps/x86_64/int-fast.h
diff --git a/sysdeps/x86_64/int-fast.h b/sysdeps/x86_64/int-fast.h
new file mode 100644
index 0000000000..8f341de646
--- /dev/null
+++ b/sysdeps/x86_64/int-fast.h
@@ -0,0 +1,50 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#ifndef _INT_FAST_X86_64_H
+#define _INT_FAST_X86_64_H 1
+
+#define __HAS_INT_FAST_DEFS 1
+
+/* Signed. */
+typedef signed char int_fast8_t;
+/* On x86_64 32-bit instructions are almost always fastest. */
+typedef int int_fast16_t;
+typedef int int_fast32_t;
+typedef long int int_fast64_t;
+
+/* Unsigned. */
+typedef unsigned char uint_fast8_t;
+/* On x86_64 32-bit instructions are almost always fastest. */
+typedef unsigned int uint_fast16_t;
+typedef unsigned int uint_fast32_t;
+typedef unsigned long int uint_fast64_t;
+
+
+# define __INT_FAST8_BASE INT8
+# define __INT_FAST16_BASE INT32
+# define __INT_FAST32_BASE INT32
+# define __INT_FAST64_BASE INT64
+
+# define __UINT_FAST8_BASE UINT8
+# define __UINT_FAST16_BASE UINT32
+# define __UINT_FAST32_BASE UINT32
+# define __UINT_FAST64_BASE UINT64
+
+# include <sysdeps/generic/int-fast.h>
+
+#endif
--
2.25.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64
2022-04-11 1:09 ` [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64 Noah Goldstein
@ 2022-04-11 2:15 ` Adam Sampson
2022-04-11 6:34 ` Florian Weimer
2022-04-14 22:24 ` Joseph Myers
1 sibling, 1 reply; 7+ messages in thread
From: Adam Sampson @ 2022-04-11 2:15 UTC (permalink / raw)
To: Noah Goldstein via Libc-alpha
Noah Goldstein via Libc-alpha <libc-alpha@sourceware.org> writes:
> {u}int_fast{16|32} should never use 64-bit types. 64-bit instructions
> often use more code size (REX prefix) and a variety of instructions
> are slower on many implementations (div, bswap, etc...).
Isn't that going to cause ABI breakage in other libraries, though?
For example, the jasper JPEG2000 decoder library uses stdint.h's
uint_fast32_t in its public API, and the HDF5 scientific data library
includes constants for the sizes of various types including *int*fast*.
Thanks,
--
Adam Sampson <ats@offog.org> <http://offog.org/>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64
2022-04-11 2:15 ` Adam Sampson
@ 2022-04-11 6:34 ` Florian Weimer
0 siblings, 0 replies; 7+ messages in thread
From: Florian Weimer @ 2022-04-11 6:34 UTC (permalink / raw)
To: Adam Sampson via Libc-alpha
* Adam Sampson via Libc-alpha:
> Noah Goldstein via Libc-alpha <libc-alpha@sourceware.org> writes:
>
>> {u}int_fast{16|32} should never use 64-bit types. 64-bit instructions
>> often use more code size (REX prefix) and a variety of instructions
>> are slower on many implementations (div, bswap, etc...).
>
> Isn't that going to cause ABI breakage in other libraries, though?
> For example, the jasper JPEG2000 decoder library uses stdint.h's
> uint_fast32_t in its public API, and the HDF5 scientific data library
> includes constants for the sizes of various types including *int*fast*.
Agreed, it's too late for such changes.
Thanks,
Florian
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint
2022-04-11 1:09 [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint Noah Goldstein
2022-04-11 1:09 ` [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64 Noah Goldstein
@ 2022-04-14 22:21 ` Joseph Myers
1 sibling, 0 replies; 7+ messages in thread
From: Joseph Myers @ 2022-04-14 22:21 UTC (permalink / raw)
To: Noah Goldstein; +Cc: libc-alpha
On Sun, 10 Apr 2022, Noah Goldstein via Libc-alpha wrote:
> The goal is to make it easier to provide system specific defs for the
> sizes of {u}int_fast{8|16|32|64}.
>
> Note this commit does not change any of the previous values.
>
> Full xcheck passes on x86_64.
> ---
> stdlib/stdint.h | 70 +-----------------------
> sysdeps/generic/int-fast.h | 107 +++++++++++++++++++++++++++++++++++++
stdint.h is an installed header, so any headers it includes must also be
installed headers (i.e. listed in headers in Makefile). Any installed
header whose name is not a public API should be in bits/, and this header
would clearly fall in that category - no user should ever #include
<int-fast.h> themselves.
--
Joseph S. Myers
joseph@codesourcery.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64
2022-04-11 1:09 ` [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64 Noah Goldstein
2022-04-11 2:15 ` Adam Sampson
@ 2022-04-14 22:24 ` Joseph Myers
2022-04-14 22:44 ` Noah Goldstein
1 sibling, 1 reply; 7+ messages in thread
From: Joseph Myers @ 2022-04-14 22:24 UTC (permalink / raw)
To: Noah Goldstein; +Cc: libc-alpha
On Sun, 10 Apr 2022, Noah Goldstein via Libc-alpha wrote:
> {u}int_fast{16|32} should never use 64-bit types. 64-bit instructions
> often use more code size (REX prefix) and a variety of instructions are
> slower on many implementations (div, bswap, etc...).
Apart from the other issues discussed with this patch, installed headers
should not be specific to either x86_64 or 32-bit x86; such headers, where
architecture-specific, should go in an x86/ sysdeps directory and contain
appropriate conditionals within the header, so a single set of installed
headers works with a multilibbed compiler.
> +# include <sysdeps/generic/int-fast.h>
And an installed header can't do that sort of thing, because only a single
version of any such header gets installed. If you want to include a
generic file it has to have a different name, with both being installed
(cf. bits/mman-*.h, for example).
--
Joseph S. Myers
joseph@codesourcery.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64
2022-04-14 22:24 ` Joseph Myers
@ 2022-04-14 22:44 ` Noah Goldstein
0 siblings, 0 replies; 7+ messages in thread
From: Noah Goldstein @ 2022-04-14 22:44 UTC (permalink / raw)
To: Joseph Myers; +Cc: GNU C Library
On Thu, Apr 14, 2022 at 5:24 PM Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Sun, 10 Apr 2022, Noah Goldstein via Libc-alpha wrote:
>
> > {u}int_fast{16|32} should never use 64-bit types. 64-bit instructions
> > often use more code size (REX prefix) and a variety of instructions are
> > slower on many implementations (div, bswap, etc...).
>
> Apart from the other issues discussed with this patch, installed headers
> should not be specific to either x86_64 or 32-bit x86; such headers, where
> architecture-specific, should go in an x86/ sysdeps directory and contain
> appropriate conditionals within the header, so a single set of installed
> headers works with a multilibbed compiler.
>
> > +# include <sysdeps/generic/int-fast.h>
>
> And an installed header can't do that sort of thing, because only a single
> version of any such header gets installed. If you want to include a
> generic file it has to have a different name, with both being installed
> (cf. bits/mman-*.h, for example).
Good info to have but the patches have been drop for the ABI concerns.
>
> --
> Joseph S. Myers
> joseph@codesourcery.com
^ permalink raw reply [flat|nested] 7+ messages in thread
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2022-04-11 2:15 ` Adam Sampson
2022-04-11 6:34 ` Florian Weimer
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2022-04-14 22:21 ` [PATCH v1 1/2] stdlib: Refactor {u}int_fast defs in stdint Joseph Myers
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