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linux/lib/zstd/common/compiler.h
Nick Terrell 2aa14b1ab2 zstd: import usptream v1.5.2 
Updates the kernel's zstd library to v1.5.2, the latest zstd release.
The upstream tag it is updated to is `v1.5.2-kernel`, which contains
several cherry-picked commits on top of the v1.5.2 release which are
required for the kernel update. I will create this tag once the PR is
ready to merge, until then reference the temporary upstream branch
`v1.5.2-kernel-cherrypicks`.

I plan to submit this patch as part of the v6.2 merge window.

I've done basic build testing & testing on x86-64, i386, and aarch64.
I'm merging these patches into my `zstd-next` branch, which is pulled
into `linux-next` for further testing.

I've benchmarked BtrFS with zstd compression on a x86-64 machine, and
saw these results. Decompression speed is a small win across the board.
The lower compression levels 1-4 see both compression speed and
compression ratio wins. The higher compression levels see a small
compression speed loss and about neutral ratio. I expect the lower
compression levels to be used much more heavily than the high
compression levels, so this should be a net win.

Level	CTime	DTime	Ratio
1	-2.95%	-1.1%	-0.7%
3	-3.5%	-1.2%	-0.5%
5	+3.7%	-1.0%	+0.0%
7	+3.2%	-0.9%	+0.0%
9	-4.3%	-0.8%	+0.1%

Signed-off-by: Nick Terrell <terrelln@fb.com>
2022-10-24 12:12:32 -07:00

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/*
* Copyright (c) Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
* You may select, at your option, one of the above-listed licenses.
*/
#ifndef ZSTD_COMPILER_H
#define ZSTD_COMPILER_H
#include "portability_macros.h"
/*-*******************************************************
* Compiler specifics
*********************************************************/
/* force inlining */
#if !defined(ZSTD_NO_INLINE)
#if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */
# define INLINE_KEYWORD inline
#else
# define INLINE_KEYWORD
#endif
#define FORCE_INLINE_ATTR __attribute__((always_inline))
#else
#define INLINE_KEYWORD
#define FORCE_INLINE_ATTR
#endif
/*
On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).
This explicitly marks such functions as __cdecl so that the code will still compile
if a CC other than __cdecl has been made the default.
*/
#define WIN_CDECL
/*
* FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
* parameters. They must be inlined for the compiler to eliminate the constant
* branches.
*/
#define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
/*
* HINT_INLINE is used to help the compiler generate better code. It is *not*
* used for "templates", so it can be tweaked based on the compilers
* performance.
*
* gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
* always_inline attribute.
*
* clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
* attribute.
*/
#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 5
# define HINT_INLINE static INLINE_KEYWORD
#else
# define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR
#endif
/* UNUSED_ATTR tells the compiler it is okay if the function is unused. */
#define UNUSED_ATTR __attribute__((unused))
/* force no inlining */
#define FORCE_NOINLINE static __attribute__((__noinline__))
/* target attribute */
#define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
/* Target attribute for BMI2 dynamic dispatch.
* Enable lzcnt, bmi, and bmi2.
* We test for bmi1 & bmi2. lzcnt is included in bmi1.
*/
#define BMI2_TARGET_ATTRIBUTE TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")
/* prefetch
* can be disabled, by declaring NO_PREFETCH build macro */
#if ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )
# define PREFETCH_L1(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 3 /* locality */)
# define PREFETCH_L2(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)
#elif defined(__aarch64__)
# define PREFETCH_L1(ptr) __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr)))
# define PREFETCH_L2(ptr) __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr)))
#else
# define PREFETCH_L1(ptr) (void)(ptr) /* disabled */
# define PREFETCH_L2(ptr) (void)(ptr) /* disabled */
#endif /* NO_PREFETCH */
#define CACHELINE_SIZE 64
#define PREFETCH_AREA(p, s) { \
const char* const _ptr = (const char*)(p); \
size_t const _size = (size_t)(s); \
size_t _pos; \
for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) { \
PREFETCH_L2(_ptr + _pos); \
} \
}
/* vectorization
* older GCC (pre gcc-4.3 picked as the cutoff) uses a different syntax,
* and some compilers, like Intel ICC and MCST LCC, do not support it at all. */
#if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__) && !defined(__LCC__)
# if (__GNUC__ == 4 && __GNUC_MINOR__ > 3) || (__GNUC__ >= 5)
# define DONT_VECTORIZE __attribute__((optimize("no-tree-vectorize")))
# else
# define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")
# endif
#else
# define DONT_VECTORIZE
#endif
/* Tell the compiler that a branch is likely or unlikely.
* Only use these macros if it causes the compiler to generate better code.
* If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc
* and clang, please do.
*/
#define LIKELY(x) (__builtin_expect((x), 1))
#define UNLIKELY(x) (__builtin_expect((x), 0))
#if __has_builtin(__builtin_unreachable) || (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))
# define ZSTD_UNREACHABLE { assert(0), __builtin_unreachable(); }
#else
# define ZSTD_UNREACHABLE { assert(0); }
#endif
/* disable warnings */
/*Like DYNAMIC_BMI2 but for compile time determination of BMI2 support*/
/* compile time determination of SIMD support */
/* C-language Attributes are added in C23. */
#if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
# define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
#else
# define ZSTD_HAS_C_ATTRIBUTE(x) 0
#endif
/* Only use C++ attributes in C++. Some compilers report support for C++
* attributes when compiling with C.
*/
#define ZSTD_HAS_CPP_ATTRIBUTE(x) 0
/* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
* - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
* - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
* - Else: __attribute__((__fallthrough__))
*/
#define ZSTD_FALLTHROUGH fallthrough
/*-**************************************************************
* Alignment check
*****************************************************************/
/* this test was initially positioned in mem.h,
* but this file is removed (or replaced) for linux kernel
* so it's now hosted in compiler.h,
* which remains valid for both user & kernel spaces.
*/
#ifndef ZSTD_ALIGNOF
/* covers gcc, clang & MSVC */
/* note : this section must come first, before C11,
* due to a limitation in the kernel source generator */
# define ZSTD_ALIGNOF(T) __alignof(T)
#endif /* ZSTD_ALIGNOF */
/*-**************************************************************
* Sanitizer
*****************************************************************/
#endif /* ZSTD_COMPILER_H */
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