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:
>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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