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 the
  6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
  7 * 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_H
 12#define ZSTD_COMPILER_H
 13
 14#include "portability_macros.h"
 15
 16/*-*******************************************************
 17*  Compiler specifics
 18*********************************************************/
 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 inline
 24#else
 25#  define INLINE_KEYWORD
 26#endif
 27
 28#define FORCE_INLINE_ATTR __attribute__((always_inline))
 29
 30#else
 31
 32#define INLINE_KEYWORD
 33#define FORCE_INLINE_ATTR
 34
 35#endif
 36
 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 compile
 40  if a CC other than __cdecl has been made the default.
 41*/
 42#define WIN_CDECL
 43
 44/*
 45 * FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
 46 * parameters. They must be inlined for the compiler to eliminate the constant
 47 * branches.
 48 */
 49#define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
 50/*
 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 compilers
 53 * performance.
 54 *
 55 * gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
 56 * always_inline attribute.
 57 *
 58 * clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
 59 * attribute.
 60 */
 61#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 5
 62#  define HINT_INLINE static INLINE_KEYWORD
 63#else
 64#  define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR
 65#endif
 66
 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/* prefetch
 84 * 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#else
 92#  define PREFETCH_L1(ptr) (void)(ptr)  /* disabled */
 93#  define PREFETCH_L2(ptr) (void)(ptr)  /* disabled */
 94#endif  /* NO_PREFETCH */
 95
 96#define CACHELINE_SIZE 64
 97
 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/* vectorization
108 * 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#  else
114#    define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")
115#  endif
116#else
117#  define DONT_VECTORIZE
118#endif
119
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 gcc
123 * 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#else
131#  define ZSTD_UNREACHABLE { assert(0); }
132#endif
133
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#else
145# define ZSTD_HAS_C_ATTRIBUTE(x) 0
146#endif
147
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) 0
152
153/* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
154 * - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
155 * - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
156 * - Else: __attribute__((__fallthrough__))
157 */
158#define ZSTD_FALLTHROUGH fallthrough
159
160/*-**************************************************************
161*  Alignment check
162*****************************************************************/
163
164/* this test was initially positioned in mem.h,
165 * but this file is removed (or replaced) for linux kernel
166 * so it's now hosted in compiler.h,
167 * which remains valid for both user & kernel spaces.
168 */
169
170#ifndef ZSTD_ALIGNOF
171/* 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*  Sanitizer
180*****************************************************************/
181
182
183
184#endif /* ZSTD_COMPILER_H */