portability_macros.h

  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 */