Date: Thu, 2 Oct 2014 17:42:21 +0000 (UTC) From: Xin LI <delphij@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r272427 - stable/8/sys/cddl/boot/zfs Message-ID: <201410021742.s92HgLNb006416@svn.freebsd.org>
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Author: delphij Date: Thu Oct 2 17:42:21 2014 New Revision: 272427 URL: https://svnweb.freebsd.org/changeset/base/272427 Log: MFC r272389: Diff reduction with kernel code: instruct the compiler that the data of these types may be unaligned to their "normal" alignment and exercise caution when accessing them. PR: 194071 Modified: stable/8/sys/cddl/boot/zfs/lz4.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/cddl/ (props changed) Modified: stable/8/sys/cddl/boot/zfs/lz4.c ============================================================================== --- stable/8/sys/cddl/boot/zfs/lz4.c Thu Oct 2 17:42:02 2014 (r272426) +++ stable/8/sys/cddl/boot/zfs/lz4.c Thu Oct 2 17:42:21 2014 (r272427) @@ -83,6 +83,17 @@ lz4_decompress(void *s_start, void *d_st #endif /* + * Unaligned memory access is automatically enabled for "common" CPU, + * such as x86. For others CPU, the compiler will be more cautious, and + * insert extra code to ensure aligned access is respected. If you know + * your target CPU supports unaligned memory access, you may want to + * force this option manually to improve performance + */ +#if defined(__ARM_FEATURE_UNALIGNED) +#define LZ4_FORCE_UNALIGNED_ACCESS 1 +#endif + +/* * Compiler Options */ #if __STDC_VERSION__ >= 199901L /* C99 */ @@ -113,6 +124,10 @@ lz4_decompress(void *s_start, void *d_st #define S32 int32_t #define U64 uint64_t +#ifndef LZ4_FORCE_UNALIGNED_ACCESS +#pragma pack(1) +#endif + typedef struct _U16_S { U16 v; } U16_S; @@ -123,6 +138,10 @@ typedef struct _U64_S { U64 v; } U64_S; +#ifndef LZ4_FORCE_UNALIGNED_ACCESS +#pragma pack() +#endif + #define A64(x) (((U64_S *)(x))->v) #define A32(x) (((U32_S *)(x))->v) #define A16(x) (((U16_S *)(x))->v)
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