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 /*-*******************************************************
15 *  Compiler specifics
16 *********************************************************/
17 /* force inlining */
18 
19 #if !defined(ZSTD_NO_INLINE)
20 #if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   /* C99 */
21 #  define INLINE_KEYWORD inline
22 #else
23 #  define INLINE_KEYWORD
24 #endif
25 
26 #define FORCE_INLINE_ATTR __attribute__((always_inline))
27 
28 #else
29 
30 #define INLINE_KEYWORD
31 #define FORCE_INLINE_ATTR
32 
33 #endif
34 
35 /*
36   On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).
37   This explictly marks such functions as __cdecl so that the code will still compile
38   if a CC other than __cdecl has been made the default.
39 */
40 #define WIN_CDECL
41 
42 /*
43  * FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
44  * parameters. They must be inlined for the compiler to eliminate the constant
45  * branches.
46  */
47 #define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
48 /*
49  * HINT_INLINE is used to help the compiler generate better code. It is *not*
50  * used for "templates", so it can be tweaked based on the compilers
51  * performance.
52  *
53  * gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
54  * always_inline attribute.
55  *
56  * clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
57  * attribute.
58  */
59 #if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 5
60 #  define HINT_INLINE static INLINE_KEYWORD
61 #else
62 #  define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR
63 #endif
64 
65 /* UNUSED_ATTR tells the compiler it is okay if the function is unused. */
66 #define UNUSED_ATTR __attribute__((unused))
67 
68 /* force no inlining */
69 #define FORCE_NOINLINE static __attribute__((__noinline__))
70 
71 
72 /* target attribute */
73 #ifndef __has_attribute
74   #define __has_attribute(x) 0  /* Compatibility with non-clang compilers. */
75 #endif
76 #define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
77 
78 /* Enable runtime BMI2 dispatch based on the CPU.
79  * Enabled for clang & gcc >=4.8 on x86 when BMI2 isn't enabled by default.
80  */
81 #ifndef DYNAMIC_BMI2
82   #if ((defined(__clang__) && __has_attribute(__target__)) \
83       || (defined(__GNUC__) \
84           && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))) \
85       && (defined(__x86_64__) || defined(_M_X86)) \
86       && !defined(__BMI2__)
87   #  define DYNAMIC_BMI2 1
88   #else
89   #  define DYNAMIC_BMI2 0
90   #endif
91 #endif
92 
93 /* prefetch
94  * can be disabled, by declaring NO_PREFETCH build macro */
95 #if ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )
96 #  define PREFETCH_L1(ptr)  __builtin_prefetch((ptr), 0 /* rw==read */, 3 /* locality */)
97 #  define PREFETCH_L2(ptr)  __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)
98 #elif defined(__aarch64__)
99 #  define PREFETCH_L1(ptr)  __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr)))
100 #  define PREFETCH_L2(ptr)  __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr)))
101 #else
102 #  define PREFETCH_L1(ptr) (void)(ptr)  /* disabled */
103 #  define PREFETCH_L2(ptr) (void)(ptr)  /* disabled */
104 #endif  /* NO_PREFETCH */
105 
106 #define CACHELINE_SIZE 64
107 
108 #define PREFETCH_AREA(p, s)  {            \
109     const char* const _ptr = (const char*)(p);  \
110     size_t const _size = (size_t)(s);     \
111     size_t _pos;                          \
112     for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) {  \
113         PREFETCH_L2(_ptr + _pos);         \
114     }                                     \
115 }
116 
117 /* vectorization
118  * older GCC (pre gcc-4.3 picked as the cutoff) uses a different syntax */
119 #if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__)
120 #  if (__GNUC__ == 4 && __GNUC_MINOR__ > 3) || (__GNUC__ >= 5)
121 #    define DONT_VECTORIZE __attribute__((optimize("no-tree-vectorize")))
122 #  else
123 #    define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")
124 #  endif
125 #else
126 #  define DONT_VECTORIZE
127 #endif
128 
129 /* Tell the compiler that a branch is likely or unlikely.
130  * Only use these macros if it causes the compiler to generate better code.
131  * If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc
132  * and clang, please do.
133  */
134 #define LIKELY(x) (__builtin_expect((x), 1))
135 #define UNLIKELY(x) (__builtin_expect((x), 0))
136 
137 /* disable warnings */
138 
139 /*Like DYNAMIC_BMI2 but for compile time determination of BMI2 support*/
140 
141 
142 /* compat. with non-clang compilers */
143 #ifndef __has_builtin
144 #  define __has_builtin(x) 0
145 #endif
146 
147 /* compat. with non-clang compilers */
148 #ifndef __has_feature
149 #  define __has_feature(x) 0
150 #endif
151 
152 /* C-language Attributes are added in C23. */
153 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
154 # define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
155 #else
156 # define ZSTD_HAS_C_ATTRIBUTE(x) 0
157 #endif
158 
159 /* Only use C++ attributes in C++. Some compilers report support for C++
160  * attributes when compiling with C.
161  */
162 #define ZSTD_HAS_CPP_ATTRIBUTE(x) 0
163 
164 /* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
165  * - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
166  * - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
167  * - Else: __attribute__((__fallthrough__))
168  */
169 #define ZSTD_FALLTHROUGH fallthrough
170 
171 /* detects whether we are being compiled under msan */
172 
173 
174 /* detects whether we are being compiled under asan */
175 
176 
177 #endif /* ZSTD_COMPILER_H */
178