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1/*2 * Copyright (c) Yann Collet, Facebook, Inc.3 * All rights reserved.4 *5 * This source code is licensed under both the BSD-style license (found in the6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found7 * in the COPYING file in the root directory of this source tree).8 * You may select, at your option, one of the above-listed licenses.9 */10 11#ifndef ZSTD_COMPILER_H12#define ZSTD_COMPILER_H13 14#include "portability_macros.h"15 16/*-*******************************************************17* Compiler specifics18*********************************************************/19/* force inlining */20 21#if !defined(ZSTD_NO_INLINE)22#if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */23# define INLINE_KEYWORD inline24#else25# define INLINE_KEYWORD26#endif27 28#define FORCE_INLINE_ATTR __attribute__((always_inline))29 30#else31 32#define INLINE_KEYWORD33#define FORCE_INLINE_ATTR34 35#endif36 37/*38 On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).39 This explicitly marks such functions as __cdecl so that the code will still compile40 if a CC other than __cdecl has been made the default.41*/42#define WIN_CDECL43 44/*45 * FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant46 * parameters. They must be inlined for the compiler to eliminate the constant47 * branches.48 */49#define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR50/*51 * HINT_INLINE is used to help the compiler generate better code. It is *not*52 * used for "templates", so it can be tweaked based on the compilers53 * performance.54 *55 * gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the56 * always_inline attribute.57 *58 * clang up to 5.0.0 (trunk) benefit tremendously from the always_inline59 * attribute.60 */61#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 562# define HINT_INLINE static INLINE_KEYWORD63#else64# define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR65#endif66 67/* UNUSED_ATTR tells the compiler it is okay if the function is unused. */68#define UNUSED_ATTR __attribute__((unused))69 70/* force no inlining */71#define FORCE_NOINLINE static __attribute__((__noinline__))72 73 74/* target attribute */75#define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))76 77/* Target attribute for BMI2 dynamic dispatch.78 * Enable lzcnt, bmi, and bmi2.79 * We test for bmi1 & bmi2. lzcnt is included in bmi1.80 */81#define BMI2_TARGET_ATTRIBUTE TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")82 83/* prefetch84 * can be disabled, by declaring NO_PREFETCH build macro */85#if ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )86# define PREFETCH_L1(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 3 /* locality */)87# define PREFETCH_L2(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)88#elif defined(__aarch64__)89# define PREFETCH_L1(ptr) __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr)))90# define PREFETCH_L2(ptr) __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr)))91#else92# define PREFETCH_L1(ptr) (void)(ptr) /* disabled */93# define PREFETCH_L2(ptr) (void)(ptr) /* disabled */94#endif /* NO_PREFETCH */95 96#define CACHELINE_SIZE 6497 98#define PREFETCH_AREA(p, s) { \99 const char* const _ptr = (const char*)(p); \100 size_t const _size = (size_t)(s); \101 size_t _pos; \102 for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) { \103 PREFETCH_L2(_ptr + _pos); \104 } \105}106 107/* vectorization108 * older GCC (pre gcc-4.3 picked as the cutoff) uses a different syntax,109 * and some compilers, like Intel ICC and MCST LCC, do not support it at all. */110#if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__) && !defined(__LCC__)111# if (__GNUC__ == 4 && __GNUC_MINOR__ > 3) || (__GNUC__ >= 5)112# define DONT_VECTORIZE __attribute__((optimize("no-tree-vectorize")))113# else114# define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")115# endif116#else117# define DONT_VECTORIZE118#endif119 120/* Tell the compiler that a branch is likely or unlikely.121 * Only use these macros if it causes the compiler to generate better code.122 * If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc123 * and clang, please do.124 */125#define LIKELY(x) (__builtin_expect((x), 1))126#define UNLIKELY(x) (__builtin_expect((x), 0))127 128#if __has_builtin(__builtin_unreachable) || (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))129# define ZSTD_UNREACHABLE { assert(0), __builtin_unreachable(); }130#else131# define ZSTD_UNREACHABLE { assert(0); }132#endif133 134/* disable warnings */135 136/*Like DYNAMIC_BMI2 but for compile time determination of BMI2 support*/137 138 139/* compile time determination of SIMD support */140 141/* C-language Attributes are added in C23. */142#if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)143# define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)144#else145# define ZSTD_HAS_C_ATTRIBUTE(x) 0146#endif147 148/* Only use C++ attributes in C++. Some compilers report support for C++149 * attributes when compiling with C.150 */151#define ZSTD_HAS_CPP_ATTRIBUTE(x) 0152 153/* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.154 * - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough155 * - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough156 * - Else: __attribute__((__fallthrough__))157 */158#define ZSTD_FALLTHROUGH fallthrough159 160/*-**************************************************************161* Alignment check162*****************************************************************/163 164/* this test was initially positioned in mem.h,165 * but this file is removed (or replaced) for linux kernel166 * so it's now hosted in compiler.h,167 * which remains valid for both user & kernel spaces.168 */169 170#ifndef ZSTD_ALIGNOF171/* covers gcc, clang & MSVC */172/* note : this section must come first, before C11,173 * due to a limitation in the kernel source generator */174# define ZSTD_ALIGNOF(T) __alignof(T)175 176#endif /* ZSTD_ALIGNOF */177 178/*-**************************************************************179* Sanitizer180*****************************************************************/181 182 183 184#endif /* ZSTD_COMPILER_H */185