2 * Copyright (c) Yann Collet, Facebook, Inc.
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.
11 #ifndef ZSTD_COMPILER_H
12 #define ZSTD_COMPILER_H
14 /*-*******************************************************
16 *********************************************************/
19 #if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */
20 # define INLINE_KEYWORD inline
22 # define INLINE_KEYWORD
25 #define FORCE_INLINE_ATTR __attribute__((always_inline))
29 On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).
30 This explictly marks such functions as __cdecl so that the code will still compile
31 if a CC other than __cdecl has been made the default.
36 * FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
37 * parameters. They must be inlined for the compiler to eliminate the constant
40 #define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
42 * HINT_INLINE is used to help the compiler generate better code. It is *not*
43 * used for "templates", so it can be tweaked based on the compilers
46 * gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
47 * always_inline attribute.
49 * clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
52 #if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 5
53 # define HINT_INLINE static INLINE_KEYWORD
55 # define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR
58 /* UNUSED_ATTR tells the compiler it is okay if the function is unused. */
59 #define UNUSED_ATTR __attribute__((unused))
61 /* force no inlining */
62 #define FORCE_NOINLINE static __attribute__((__noinline__))
65 /* target attribute */
66 #ifndef __has_attribute
67 #define __has_attribute(x) 0 /* Compatibility with non-clang compilers. */
69 #define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
71 /* Enable runtime BMI2 dispatch based on the CPU.
72 * Enabled for clang & gcc >=4.8 on x86 when BMI2 isn't enabled by default.
75 #if ((defined(__clang__) && __has_attribute(__target__)) \
76 || (defined(__GNUC__) \
77 && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))) \
78 && (defined(__x86_64__) || defined(_M_X86)) \
80 # define DYNAMIC_BMI2 1
82 # define DYNAMIC_BMI2 0
87 * can be disabled, by declaring NO_PREFETCH build macro */
88 #if ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )
89 # define PREFETCH_L1(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 3 /* locality */)
90 # define PREFETCH_L2(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)
91 #elif defined(__aarch64__)
92 # define PREFETCH_L1(ptr) __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr)))
93 # define PREFETCH_L2(ptr) __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr)))
95 # define PREFETCH_L1(ptr) (void)(ptr) /* disabled */
96 # define PREFETCH_L2(ptr) (void)(ptr) /* disabled */
97 #endif /* NO_PREFETCH */
99 #define CACHELINE_SIZE 64
101 #define PREFETCH_AREA(p, s) { \
102 const char* const _ptr = (const char*)(p); \
103 size_t const _size = (size_t)(s); \
105 for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) { \
106 PREFETCH_L2(_ptr + _pos); \
111 * older GCC (pre gcc-4.3 picked as the cutoff) uses a different syntax */
112 #if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__)
113 # if (__GNUC__ == 4 && __GNUC_MINOR__ > 3) || (__GNUC__ >= 5)
114 # define DONT_VECTORIZE __attribute__((optimize("no-tree-vectorize")))
116 # define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")
119 # define DONT_VECTORIZE
122 /* Tell the compiler that a branch is likely or unlikely.
123 * Only use these macros if it causes the compiler to generate better code.
124 * If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc
125 * and clang, please do.
127 #define LIKELY(x) (__builtin_expect((x), 1))
128 #define UNLIKELY(x) (__builtin_expect((x), 0))
130 /* disable warnings */
132 /*Like DYNAMIC_BMI2 but for compile time determination of BMI2 support*/
135 /* compat. with non-clang compilers */
136 #ifndef __has_builtin
137 # define __has_builtin(x) 0
140 /* compat. with non-clang compilers */
141 #ifndef __has_feature
142 # define __has_feature(x) 0
145 /* C-language Attributes are added in C23. */
146 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
147 # define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
149 # define ZSTD_HAS_C_ATTRIBUTE(x) 0
152 /* Only use C++ attributes in C++. Some compilers report support for C++
153 * attributes when compiling with C.
155 #define ZSTD_HAS_CPP_ATTRIBUTE(x) 0
157 /* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
158 * - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
159 * - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
160 * - Else: __attribute__((__fallthrough__))
162 #define ZSTD_FALLTHROUGH fallthrough
164 /* detects whether we are being compiled under msan */
167 /* detects whether we are being compiled under asan */
170 #endif /* ZSTD_COMPILER_H */