[PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Jakub Jelinek]

Hi!

alpha (ev67), ia64 and powerpc (power5 and later) implement popcount
in hardware.  For alpha I have used inline assembly, because
__builtin_popcount would only expand to ctpop if the selected gcc
arch is ev67, which isn't sure.  Calling libgcc function there is not a good
idea.  On ia64 we can use it unconditionally, for ppc only for power5 and
later, but inline asm would be larger there, so I use the builtin guarded
with predefined macro for power5 and later.
glibc build supports only GCC 3.4 and later, so __builtin_popcountl
is supported.

2007-07-17  Jakub Jelinek  <jakub@redhat.com>

	* sysdeps/alpha/alphaev67/sched_cpucount.c: New file.
	* sysdeps/ia64/sched_cpucount.c: New file.
	* sysdeps/powerpc/sched_cpucount.c: New file.

--- libc/sysdeps/alpha/alphaev67/sched_cpucount.c.jj	2007-07-17 22:21:33.000000000 +0200
+++ libc/sysdeps/alpha/alphaev67/sched_cpucount.c	2007-07-17 22:22:37.000000000 +0200
@@ -0,0 +1,24 @@
+/* Copyright (C) 2007 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#define POPCNT(l) \
+  ({ __cpu_mask r;							      \
+     asm ("ctpop %1, %0" : "=r" (r) : "0" (l));				      \
+     r; })
+
+#include <posix/sched_cpucount.c>
--- libc/sysdeps/ia64/sched_cpucount.c.jj	2007-07-17 22:21:33.000000000 +0200
+++ libc/sysdeps/ia64/sched_cpucount.c	2007-07-17 22:25:50.000000000 +0200
@@ -0,0 +1,21 @@
+/* Copyright (C) 2007 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#define POPCNT(l) __builtin_popcountl (l)
+
+#include <posix/sched_cpucount.c>
--- libc/sysdeps/powerpc/sched_cpucount.c.jj	2007-07-17 22:21:33.000000000 +0200
+++ libc/sysdeps/powerpc/sched_cpucount.c	2007-07-17 22:34:26.000000000 +0200
@@ -0,0 +1,23 @@
+/* Copyright (C) 2007 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifdef _ARCH_PWR5
+# define POPCNT(l) __builtin_popcountl (l)
+#endif
+
+#include <posix/sched_cpucount.c>

	Jakub

Re: [PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Roland McGrath]

Seems like this might come up somewhere else.  I'd be inclined to add a
sysdeps header file for POPCNT alone (or rename it).


Thanks,
Roland

Re: [PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Jakub Jelinek]

On Tue, Jul 17, 2007 at 01:53:04PM -0700, Roland McGrath wrote:
> Seems like this might come up somewhere else.  I'd be inclined to add a
> sysdeps header file for POPCNT alone (or rename it).

Maybe, though I'm not sure if we need one sysdep header for each such a
macro, that might be an overkill.

	Jakub

Re: [PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Roland McGrath]

> Maybe, though I'm not sure if we need one sysdep header for each such a
> macro, that might be an overkill.

No, one header for all macros of the ilk that come along would be fine.  
At a stretch, sysdeps/CPU/sysdep.h might even do.  

I almost suggested just adding it to bits/atomic.h, but it is probably
preferable to segregate miscellanea from atomic/lock stuff in particular.


Thanks,
Roland

Re: [PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Ulrich Drepper]

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Roland McGrath wrote:
> Seems like this might come up somewhere else.  I'd be inclined to add a
> sysdeps header file for POPCNT alone (or rename it).

Seems like a lot of work with questionable benefit.  In all the years we
have found one single place in glibc for this operation.  I'm happy with
the current patch.  We cann always change it later if the assumption
that it is not widely needed turns out wrong.

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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Re: [PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Richard Henderson]

On Tue, Jul 17, 2007 at 10:47:19PM +0200, Jakub Jelinek wrote:
> in hardware.  For alpha I have used inline assembly, because
> __builtin_popcount would only expand to ctpop if the selected gcc
> arch is ev67, which isn't sure.

#ifdef __alpha_cix__
# define POPCNT(l) __builtin_popcountl (l)
#endif


r~

Re: [PATCH] Optimized __sched_cpucount for alphaev67, power5 and above and ia64

[Ulrich Drepper]

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I left out the Alpha version since after rth's comment I don't know
where in the alpha hierarchy the file should be placed.  Richard, please
check in an appropriate file.

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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