>
> Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote on 2010/01/14
> 09:57:11:
> >
> >
> > > Seen it now as it is in Linus tree:
> > >
> > > 1) IMHO it would have been nicer to use #ifdef __KERNEL__
> > > instead of CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> > > as then arches that don't define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> > > at all will never use the new optimization or was that what you
> > > intended?
> >
> > No, that was on purpose. If an arch doesn't have efficient unaligned
> > accesses, then they should not use the optimization since it will result
> > in a lot of unaligned accesses :-) In which case they are better off
> > falling back to the old byte-by-byte method.
> >
> > The advantage also of doing it this way is that x86 will benefit from
> > the optimisation at boot time since it does include autoconf.h in its
> > boot wrapper (and deals with unaligned accesses just fine at any time)
> > though something tells me that it won't make much of a difference in
> > performances on any recent x86 (it might on some of the newer low power
> > embedded ones, I don't know for sure).
> >
> > > 2) You really should add an comment in the Makefile about not using
> > > autoconf.h/-D__KERNEL__
> >
> > That's true :-)
>
> So I fixed the new inflate to be endian independent and now
> all arches can use the optimized version. Here goes:
No comments so far, I guess that is a good thing :)
Ben, Andrew could either of you carry this patch for me?
Jocke
>
>
> From 4e769486e2520e34f532a2d4bf13ab13f05e3e76 Mon Sep 17 00:00:00 2001
> From: Joakim Tjernlund <joakim.tjernl...@transmode.se>
> Date: Sun, 24 Jan 2010 11:12:56 +0100
> Subject: [PATCH] zlib: Make new optimized inflate endian independent
>
> Commit 6846ee5ca68d81e6baccf0d56221d7a00c1be18b made the
> new optimized inflate only available on arch's that
> define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS. This
> fixes it by defining our own endian independent versions
> of unaligned access.
>
> Signed-off-by: Joakim Tjernlund <joakim.tjernl...@transmode.se>
> ---
> lib/zlib_inflate/inffast.c | 70
> +++++++++++++++++++-------------------------
> 1 files changed, 30 insertions(+), 40 deletions(-)
>
> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
> index 215447c..5de16f4 100644
> --- a/lib/zlib_inflate/inffast.c
> +++ b/lib/zlib_inflate/inffast.c
> @@ -8,21 +8,6 @@
> #include "inflate.h"
> #include "inffast.h"
>
> -/* Only do the unaligned "Faster" variant when
> - * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is set
> - *
> - * On powerpc, it won't be as we don't include autoconf.h
> - * automatically for the boot wrapper, which is intended as
> - * we run in an environment where we may not be able to deal
> - * with (even rare) alignment faults. In addition, we do not
> - * define __KERNEL__ for arch/powerpc/boot unlike x86
> - */
> -
> -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> -#include <asm/unaligned.h>
> -#include <asm/byteorder.h>
> -#endif
> -
> #ifndef ASMINF
>
> /* Allow machine dependent optimization for post-increment or pre-increment.
> @@ -36,14 +21,31 @@
> - Pentium III (Anderson)
> - M68060 (Nikl)
> */
> +union uu {
> + unsigned short us;
> + unsigned char b[2];
> +};
> +
> +/* Endian independed version */
> +static inline unsigned short
> +get_unaligned16(const unsigned short *p)
> +{
> + union uu mm;
> + unsigned char *b = (unsigned char *)p;
> +
> + mm.b[0] = b[0];
> + mm.b[1] = b[1];
> + return mm.us;
> +}
> +
> #ifdef POSTINC
> # define OFF 0
> # define PUP(a) *(a)++
> -# define UP_UNALIGNED(a) get_unaligned((a)++)
> +# define UP_UNALIGNED(a) get_unaligned16((a)++)
> #else
> # define OFF 1
> # define PUP(a) *++(a)
> -# define UP_UNALIGNED(a) get_unaligned(++(a))
> +# define UP_UNALIGNED(a) get_unaligned16(++(a))
> #endif
>
> /*
> @@ -256,7 +258,6 @@ void inflate_fast(z_streamp strm, unsigned start)
> }
> }
> else {
> -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> unsigned short *sout;
> unsigned long loops;
>
> @@ -274,7 +275,11 @@ void inflate_fast(z_streamp strm, unsigned start)
> sfrom = (unsigned short *)(from - OFF);
> loops = len >> 1;
> do
> +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> + PUP(sout) = PUP(sfrom);
> +#else
> PUP(sout) = UP_UNALIGNED(sfrom);
> +#endif
> while (--loops);
> out = (unsigned char *)sout + OFF;
> from = (unsigned char *)sfrom + OFF;
> @@ -282,14 +287,13 @@ void inflate_fast(z_streamp strm, unsigned start)
> unsigned short pat16;
>
> pat16 = *(sout-2+2*OFF);
> - if (dist == 1)
> -#if defined(__BIG_ENDIAN)
> - pat16 = (pat16 & 0xff) | ((pat16 & 0xff) << 8);
> -#elif defined(__LITTLE_ENDIAN)
> - pat16 = (pat16 & 0xff00) | ((pat16 & 0xff00) >> 8);
> -#else
> -#error __BIG_ENDIAN nor __LITTLE_ENDIAN is defined
> -#endif
> + if (dist == 1) {
> + union uu mm;
> + /* copy one char pattern to both bytes */
> + mm.us = pat16;
> + mm.b[0] = mm.b[1];
> + pat16 = mm.us;
> + }
> loops = len >> 1;
> do
> PUP(sout) = pat16;
> @@ -298,20 +302,6 @@ void inflate_fast(z_streamp strm, unsigned start)
> }
> if (len & 1)
> PUP(out) = PUP(from);
> -#else /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
> - from = out - dist; /* copy direct from output */
> - do { /* minimum length is three */
> - PUP(out) = PUP(from);
> - PUP(out) = PUP(from);
> - PUP(out) = PUP(from);
> - len -= 3;
> - } while (len > 2);
> - if (len) {
> - PUP(out) = PUP(from);
> - if (len > 1)
> - PUP(out) = PUP(from);
> - }
> -#endif /* !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
> }
> }
> else if ((op & 64) == 0) { /* 2nd level distance code */
> --
> 1.6.4.4
>
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