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Diff reduction with kernel code: instruct the compiler that the data of

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these types may be unaligned to their "normal" alignment and exercise
caution when accessing them.

PR:		194071
MFC after:	3 days
This commit is contained in:
Xin LI 2014-10-02 00:13:08 +00:00
parent 1a6804c649
commit 43ac3722ac
1 changed files with 19 additions and 0 deletions
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19
sys/cddl/boot/zfs/lz4.c
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@ -82,6 +82,17 @@ lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int dum
*/
#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
*/
@ -113,6 +124,10 @@ lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int dum
#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)