xref: /linux/lib/zstd/common/portability_macros.h (revision e61f33273ca755b3e2ebee4520a76097199dc7a8)
1 /* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
2 /*
3  * Copyright (c) Meta Platforms, Inc. and affiliates.
4  * All rights reserved.
5  *
6  * This source code is licensed under both the BSD-style license (found in the
7  * LICENSE file in the root directory of this source tree) and the GPLv2 (found
8  * in the COPYING file in the root directory of this source tree).
9  * You may select, at your option, one of the above-listed licenses.
10  */
11 
12 #ifndef ZSTD_PORTABILITY_MACROS_H
13 #define ZSTD_PORTABILITY_MACROS_H
14 
15 /*
16  * This header file contains macro definitions to support portability.
17  * This header is shared between C and ASM code, so it MUST only
18  * contain macro definitions. It MUST not contain any C code.
19  *
20  * This header ONLY defines macros to detect platforms/feature support.
21  *
22  */
23 
24 
25 /* compat. with non-clang compilers */
26 #ifndef __has_attribute
27   #define __has_attribute(x) 0
28 #endif
29 
30 /* compat. with non-clang compilers */
31 #ifndef __has_builtin
32 #  define __has_builtin(x) 0
33 #endif
34 
35 /* compat. with non-clang compilers */
36 #ifndef __has_feature
37 #  define __has_feature(x) 0
38 #endif
39 
40 /* detects whether we are being compiled under msan */
41 
42 /* detects whether we are being compiled under asan */
43 
44 /* detects whether we are being compiled under dfsan */
45 
46 /* Mark the internal assembly functions as hidden  */
47 #ifdef __ELF__
48 # define ZSTD_HIDE_ASM_FUNCTION(func) .hidden func
49 #elif defined(__APPLE__)
50 # define ZSTD_HIDE_ASM_FUNCTION(func) .private_extern func
51 #else
52 # define ZSTD_HIDE_ASM_FUNCTION(func)
53 #endif
54 
55 /* Compile time determination of BMI2 support */
56 
57 
58 /* Enable runtime BMI2 dispatch based on the CPU.
59  * Enabled for clang & gcc >=4.8 on x86 when BMI2 isn't enabled by default.
60  */
61 #ifndef DYNAMIC_BMI2
62 #  if ((defined(__clang__) && __has_attribute(__target__)) \
63       || (defined(__GNUC__) \
64           && (__GNUC__ >= 11))) \
65       && (defined(__i386__) || defined(__x86_64__) || defined(_M_IX86) || defined(_M_X64)) \
66       && !defined(__BMI2__)
67 #    define DYNAMIC_BMI2 1
68 #  else
69 #    define DYNAMIC_BMI2 0
70 #  endif
71 #endif
72 
73 /*
74  * Only enable assembly for GNU C compatible compilers,
75  * because other platforms may not support GAS assembly syntax.
76  *
77  * Only enable assembly for Linux / MacOS / Win32, other platforms may
78  * work, but they haven't been tested. This could likely be
79  * extended to BSD systems.
80  *
81  * Disable assembly when MSAN is enabled, because MSAN requires
82  * 100% of code to be instrumented to work.
83  */
84 #define ZSTD_ASM_SUPPORTED 1
85 
86 /*
87  * Determines whether we should enable assembly for x86-64
88  * with BMI2.
89  *
90  * Enable if all of the following conditions hold:
91  * - ASM hasn't been explicitly disabled by defining ZSTD_DISABLE_ASM
92  * - Assembly is supported
93  * - We are compiling for x86-64 and either:
94  *   - DYNAMIC_BMI2 is enabled
95  *   - BMI2 is supported at compile time
96  */
97 #define ZSTD_ENABLE_ASM_X86_64_BMI2 0
98 
99 /*
100  * For x86 ELF targets, add .note.gnu.property section for Intel CET in
101  * assembly sources when CET is enabled.
102  *
103  * Additionally, any function that may be called indirectly must begin
104  * with ZSTD_CET_ENDBRANCH.
105  */
106 #if defined(__ELF__) && (defined(__x86_64__) || defined(__i386__)) \
107     && defined(__has_include)
108 # if __has_include(<cet.h>)
109 #  include <cet.h>
110 #  define ZSTD_CET_ENDBRANCH _CET_ENDBR
111 # endif
112 #endif
113 
114 #ifndef ZSTD_CET_ENDBRANCH
115 # define ZSTD_CET_ENDBRANCH
116 #endif
117 
118 #endif /* ZSTD_PORTABILITY_MACROS_H */
119