linux-kernel - [PATCH 3/6] lib/lzo: 64-bit CTZ on Arm aarch64

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Date:   Wed, 21 Nov 2018 11:59:33 +0000
From:   Dave Rodgman <dave.rodgman@....com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     nd <nd@....com>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Matt Sealey <Matt.Sealey@....com>,
        "nitingupta910@...il.com" <nitingupta910@...il.com>,
        "rpurdie@...nedhand.com" <rpurdie@...nedhand.com>,
        "markus@...rhumer.com" <markus@...rhumer.com>,
        "minchan@...nel.org" <minchan@...nel.org>,
        "sergey.senozhatsky.work@...il.com" 
        <sergey.senozhatsky.work@...il.com>
Subject: [PATCH 3/6] lib/lzo: 64-bit CTZ on Arm aarch64

From: Matt Sealey <matt.sealey@....com>

LZO leaves some performance on the table by not realising that AArch64 can
optimize count-trailing-zeros bit operations.

Add __aarch64__ to the checked definitions alongside __x86_64__ to enable
the use of rbit/clz instructions on full 64-bit quantities.

Signed-off-by: Matt Sealey <matt.sealey@....com>
Signed-off-by: Dave Rodgman <dave.rodgman@....com>
---
 lib/lzo/lzodefs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/lzo/lzodefs.h b/lib/lzo/lzodefs.h
index a9927bbce21f..d167f8fc6795 100644
--- a/lib/lzo/lzodefs.h
+++ b/lib/lzo/lzodefs.h
@@ -28,7 +28,7 @@
 
 #if defined(__BIG_ENDIAN) && defined(__LITTLE_ENDIAN)
 #error "conflicting endian definitions"
-#elif defined(__x86_64__)
+#elif defined(__x86_64__) || defined(__aarch64__)
 #define LZO_USE_CTZ64	1
 #define LZO_USE_CTZ32	1
 #elif defined(__i386__) || defined(__powerpc__)
-- 
2.16.4