FreeBSD/Linux Kernel Cross Reference
sys/contrib/zstd/lib/common/portability_macros.h

     /*
      * Copyright (c) Facebook, Inc.
      * All rights reserved.
      *
      * This source code is licensed under both the BSD-style license (found in the
      * LICENSE file in the root directory of this source tree) and the GPLv2 (found
      * in the COPYING file in the root directory of this source tree).
      * You may select, at your option, one of the above-listed licenses.
      */
    
    #ifndef ZSTD_PORTABILITY_MACROS_H
    #define ZSTD_PORTABILITY_MACROS_H
    
    /**
     * This header file contains macro defintions to support portability.
     * This header is shared between C and ASM code, so it MUST only
     * contain macro definitions. It MUST not contain any C code.
     *
     * This header ONLY defines macros to detect platforms/feature support.
     *
     */
    
    
    /* compat. with non-clang compilers */
    #ifndef __has_attribute
      #define __has_attribute(x) 0
    #endif
    
    /* compat. with non-clang compilers */
    #ifndef __has_builtin
    #  define __has_builtin(x) 0
    #endif
    
    /* compat. with non-clang compilers */
    #ifndef __has_feature
    #  define __has_feature(x) 0
    #endif
    
    /* detects whether we are being compiled under msan */
    #ifndef ZSTD_MEMORY_SANITIZER
    #  if __has_feature(memory_sanitizer)
    #    define ZSTD_MEMORY_SANITIZER 1
    #  else
    #    define ZSTD_MEMORY_SANITIZER 0
    #  endif
    #endif
    
    /* detects whether we are being compiled under asan */
    #ifndef ZSTD_ADDRESS_SANITIZER
    #  if __has_feature(address_sanitizer)
    #    define ZSTD_ADDRESS_SANITIZER 1
    #  elif defined(__SANITIZE_ADDRESS__)
    #    define ZSTD_ADDRESS_SANITIZER 1
    #  else
    #    define ZSTD_ADDRESS_SANITIZER 0
    #  endif
    #endif
    
    /* detects whether we are being compiled under dfsan */
    #ifndef ZSTD_DATAFLOW_SANITIZER
    # if __has_feature(dataflow_sanitizer)
    #  define ZSTD_DATAFLOW_SANITIZER 1
    # else
    #  define ZSTD_DATAFLOW_SANITIZER 0
    # endif
    #endif
    
    /* Mark the internal assembly functions as hidden  */
    #ifdef __ELF__
    # define ZSTD_HIDE_ASM_FUNCTION(func) .hidden func
    #else
    # define ZSTD_HIDE_ASM_FUNCTION(func)
    #endif
    
    /* Enable runtime BMI2 dispatch based on the CPU.
     * Enabled for clang & gcc >=4.8 on x86 when BMI2 isn't enabled by default.
     */
    #ifndef DYNAMIC_BMI2
      #if ((defined(__clang__) && __has_attribute(__target__)) \
          || (defined(__GNUC__) \
              && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))) \
          && (defined(__x86_64__) || defined(_M_X64)) \
          && !defined(__BMI2__)
      #  define DYNAMIC_BMI2 1
      #else
      #  define DYNAMIC_BMI2 0
      #endif
    #endif
    
    /**
     * Only enable assembly for GNUC comptabile compilers,
     * because other platforms may not support GAS assembly syntax.
     *
     * Only enable assembly for Linux / MacOS, other platforms may
     * work, but they haven't been tested. This could likely be
     * extended to BSD systems.
     *
     * Disable assembly when MSAN is enabled, because MSAN requires
     * 100% of code to be instrumented to work.
    */
   #if defined(__GNUC__)
   #  if defined(__linux__) || defined(__linux) || defined(__APPLE__)
   #    if ZSTD_MEMORY_SANITIZER
   #      define ZSTD_ASM_SUPPORTED 0
   #    elif ZSTD_DATAFLOW_SANITIZER
   #      define ZSTD_ASM_SUPPORTED 0
   #    else
   #      define ZSTD_ASM_SUPPORTED 1
   #    endif
   #  else
   #    define ZSTD_ASM_SUPPORTED 0
   #  endif
   #else
   #  define ZSTD_ASM_SUPPORTED 0
   #endif
   
   /**
    * Determines whether we should enable assembly for x86-64
    * with BMI2.
    *
    * Enable if all of the following conditions hold:
    * - ASM hasn't been explicitly disabled by defining ZSTD_DISABLE_ASM
    * - Assembly is supported
    * - We are compiling for x86-64 and either:
    *   - DYNAMIC_BMI2 is enabled
    *   - BMI2 is supported at compile time
    */
   #if !defined(ZSTD_DISABLE_ASM) &&                                 \
       ZSTD_ASM_SUPPORTED &&                                         \
       defined(__x86_64__) &&                                        \
       (DYNAMIC_BMI2 || defined(__BMI2__))
   # define ZSTD_ENABLE_ASM_X86_64_BMI2 1
   #else
   # define ZSTD_ENABLE_ASM_X86_64_BMI2 0
   #endif
   
   #endif /* ZSTD_PORTABILITY_MACROS_H */

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