compiler.h

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/*
 * Copyright (c) 2016-2020, Yann Collet, 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_COMPILER_H
#define ZSTD_COMPILER_H
 
/*-*******************************************************
*  Compiler specifics
*********************************************************/
/* force inlining */
 
#if !defined(ZSTD_NO_INLINE)
#if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   /* C99 */
#  define INLINE_KEYWORD inline
#else
#  define INLINE_KEYWORD
#endif
 
#if defined(__GNUC__) || defined(__ICCARM__)
#  define FORCE_INLINE_ATTR __attribute__((always_inline))
#elif defined(_MSC_VER)
#  define FORCE_INLINE_ATTR __forceinline
#else
#  define FORCE_INLINE_ATTR
#endif
 
#else
 
#define INLINE_KEYWORD
#define FORCE_INLINE_ATTR
 
#endif
 
#define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 5
#  define HINT_INLINE static INLINE_KEYWORD
#else
#  define HINT_INLINE static INLINE_KEYWORD FORCE_INLINE_ATTR
#endif
 
/* UNUSED_ATTR tells the compiler it is okay if the function is unused. */
#if defined(__GNUC__)
#  define UNUSED_ATTR __attribute__((unused))
#else
#  define UNUSED_ATTR
#endif
 
/* force no inlining */
#ifdef _MSC_VER
#  define FORCE_NOINLINE static __declspec(noinline)
#else
#  if defined(__GNUC__) || defined(__ICCARM__)
#    define FORCE_NOINLINE static __attribute__((__noinline__))
#  else
#    define FORCE_NOINLINE static
#  endif
#endif
 
/* target attribute */
#ifndef __has_attribute
  #define __has_attribute(x) 0  /* Compatibility with non-clang compilers. */
#endif
#if defined(__GNUC__) || defined(__ICCARM__)
#  define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
#else
#  define TARGET_ATTRIBUTE(target)
#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_X86)) \
      && !defined(__BMI2__)
  #  define DYNAMIC_BMI2 1
  #else
  #  define DYNAMIC_BMI2 0
  #endif
#endif
 
/* prefetch
 * can be disabled, by declaring NO_PREFETCH build macro */
#if defined(NO_PREFETCH)
#  define PREFETCH_L1(ptr)  (void)(ptr)  /* disabled */
#  define PREFETCH_L2(ptr)  (void)(ptr)  /* disabled */
#else
#  if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_I86))  /* _mm_prefetch() is not defined outside of x86/x64 */
#    include <mmintrin.h>   /* https://learn.microsoft.com/fr-fr/previous-versions/visualstudio/visual-studio-2008/84szxsww(v=vs.90) */
#    define PREFETCH_L1(ptr)  _mm_prefetch((const char*)(ptr), _MM_HINT_T0)
#    define PREFETCH_L2(ptr)  _mm_prefetch((const char*)(ptr), _MM_HINT_T1)
#  elif defined(_MSC_VER) && defined(_M_ARM64)
#    include <intrin.h>
#    define PREFETCH_L1(ptr)  __prefetch((const void*)(ptr))
#    define PREFETCH_L2(ptr)  __prefetch2((const void*)(ptr), 2 /* pldl2keep */)
#    elif defined(__aarch64__)
#     define PREFETCH_L1(ptr)  __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr)))
#     define PREFETCH_L2(ptr)  __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr)))
#  elif defined(__GNUC__) && ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )
#    define PREFETCH_L1(ptr)  __builtin_prefetch((ptr), 0 /* rw==read */, 3 /* locality */)
#    define PREFETCH_L2(ptr)  __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)
#  else
#    define PREFETCH_L1(ptr) (void)(ptr)  /* disabled */
#    define PREFETCH_L2(ptr) (void)(ptr)  /* disabled */
#  endif
#endif  /* NO_PREFETCH */
 
#define CACHELINE_SIZE 64
 
#define PREFETCH_AREA(p, s)  {            \
    const char* const _ptr = (const char*)(p);  \
    size_t const _size = (size_t)(s);     \
    size_t _pos;                          \
    for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) {  \
        PREFETCH_L2(_ptr + _pos);         \
    }                                     \
}
 
/* vectorization
 * older GCC (pre gcc-4.3 picked as the cutoff) uses a different syntax */
#if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__)
#  if (__GNUC__ == 4 && __GNUC_MINOR__ > 3) || (__GNUC__ >= 5)
#    define DONT_VECTORIZE __attribute__((optimize("no-tree-vectorize")))
#  else
#    define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")
#  endif
#else
#  define DONT_VECTORIZE
#endif
 
/* Tell the compiler that a branch is likely or unlikely.
 * Only use these macros if it causes the compiler to generate better code.
 * If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc
 * and clang, please do.
 */
#if defined(__GNUC__)
#define LIKELY(x) (__builtin_expect((x), 1))
#define UNLIKELY(x) (__builtin_expect((x), 0))
#else
#define LIKELY(x) (x)
#define UNLIKELY(x) (x)
#endif
 
/* disable warnings */
#ifdef _MSC_VER    /* Visual Studio */
#  include <intrin.h>                    /* For Visual 2005 */
#  pragma warning(disable : 4100)        /* disable: C4100: unreferenced formal parameter */
#  pragma warning(disable : 4127)        /* disable: C4127: conditional expression is constant */
#  pragma warning(disable : 4204)        /* disable: C4204: non-constant aggregate initializer */
#  pragma warning(disable : 4214)        /* disable: C4214: non-int bitfields */
#  pragma warning(disable : 4324)        /* disable: C4324: padded structure */
#endif
 
#endif /* ZSTD_COMPILER_H */