lib/zstd/common/compiler.h - linux - Git at Google

 /*
  * Copyright (c) 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

 #include "portability_macros.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

 #define FORCE_INLINE_ATTR __attribute__((always_inline))

 #else

 #define INLINE_KEYWORD
 #define FORCE_INLINE_ATTR

 #endif

 /*
   On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).
   This explicitly marks such functions as __cdecl so that the code will still compile
   if a CC other than __cdecl has been made the default.
 */
 #define WIN_CDECL

 /*
  * FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
  * parameters. They must be inlined for the compiler to eliminate the constant
  * branches.
  */
 #define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
 /*
  * HINT_INLINE is used to help the compiler generate better code. It is *not*
  * used for "templates", so it can be tweaked based on the compilers
  * performance.
  *
  * gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
  * always_inline attribute.
  *
  * clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
  * attribute.
  */
 #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. */
 #define UNUSED_ATTR __attribute__((unused))

 /* force no inlining */
 #define FORCE_NOINLINE static __attribute__((__noinline__))


 /* target attribute */
 #define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))

 /* Target attribute for BMI2 dynamic dispatch.
  * Enable lzcnt, bmi, and bmi2.
  * We test for bmi1 & bmi2. lzcnt is included in bmi1.
  */
 #define BMI2_TARGET_ATTRIBUTE TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")

 /* prefetch
  * can be disabled, by declaring NO_PREFETCH build macro */
 #if ( (__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 */)
 #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)))
 #else
 #  define PREFETCH_L1(ptr) (void)(ptr)  /* disabled */
 #  define PREFETCH_L2(ptr) (void)(ptr)  /* disabled */
 #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,
  * and some compilers, like Intel ICC and MCST LCC, do not support it at all. */
 #if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__) && !defined(__LCC__)
 #  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.
  */
 #define LIKELY(x) (__builtin_expect((x), 1))
 #define UNLIKELY(x) (__builtin_expect((x), 0))

 #if __has_builtin(__builtin_unreachable) || (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))
 #  define ZSTD_UNREACHABLE { assert(0), __builtin_unreachable(); }
 #else
 #  define ZSTD_UNREACHABLE { assert(0); }
 #endif

 /* disable warnings */

 /*Like DYNAMIC_BMI2 but for compile time determination of BMI2 support*/


 /* compile time determination of SIMD support */

 /* C-language Attributes are added in C23. */
 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
 # define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
 #else
 # define ZSTD_HAS_C_ATTRIBUTE(x) 0
 #endif

 /* Only use C++ attributes in C++. Some compilers report support for C++
  * attributes when compiling with C.
  */
 #define ZSTD_HAS_CPP_ATTRIBUTE(x) 0

 /* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
  * - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
  * - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
  * - Else: __attribute__((__fallthrough__))
  */
 #define ZSTD_FALLTHROUGH fallthrough

 /*-**************************************************************
 *  Alignment check
 *****************************************************************/

 /* this test was initially positioned in mem.h,
  * but this file is removed (or replaced) for linux kernel
  * so it's now hosted in compiler.h,
  * which remains valid for both user & kernel spaces.
  */

 #ifndef ZSTD_ALIGNOF
 /* covers gcc, clang & MSVC */
 /* note : this section must come first, before C11,
  * due to a limitation in the kernel source generator */
 #  define ZSTD_ALIGNOF(T) __alignof(T)

 #endif /* ZSTD_ALIGNOF */

 /*-**************************************************************
 *  Sanitizer
 *****************************************************************/


 #endif /* ZSTD_COMPILER_H */
	/*
	* Copyright (c) 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

	#include "portability_macros.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

	#define FORCE_INLINE_ATTR __attribute__((always_inline))

	#else

	#define INLINE_KEYWORD
	#define FORCE_INLINE_ATTR

	#endif

	/*
	On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).
	This explicitly marks such functions as __cdecl so that the code will still compile
	if a CC other than __cdecl has been made the default.
	*/
	#define WIN_CDECL

	/*
	* FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
	* parameters. They must be inlined for the compiler to eliminate the constant
	* branches.
	*/
	#define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR
	/*
	* HINT_INLINE is used to help the compiler generate better code. It is not
	* used for "templates", so it can be tweaked based on the compilers
	* performance.
	*
	* gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
	* always_inline attribute.
	*
	* clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
	* attribute.
	*/
	#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. */
	#define UNUSED_ATTR __attribute__((unused))

	/* force no inlining */
	#define FORCE_NOINLINE static __attribute__((__noinline__))


	/* target attribute */
	#define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))

	/* Target attribute for BMI2 dynamic dispatch.
	* Enable lzcnt, bmi, and bmi2.
	* We test for bmi1 & bmi2. lzcnt is included in bmi1.
	*/
	#define BMI2_TARGET_ATTRIBUTE TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")

	/* prefetch
	* can be disabled, by declaring NO_PREFETCH build macro */
	#if ( (__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 */)
	#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)))
	#else
	# define PREFETCH_L1(ptr) (void)(ptr) /* disabled */
	# define PREFETCH_L2(ptr) (void)(ptr) /* disabled */
	#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,
	* and some compilers, like Intel ICC and MCST LCC, do not support it at all. */
	#if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__) && !defined(__LCC__)
	# 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.
	*/
	#define LIKELY(x) (__builtin_expect((x), 1))
	#define UNLIKELY(x) (__builtin_expect((x), 0))

	#if __has_builtin(__builtin_unreachable) \|\| (defined(__GNUC__) && (__GNUC__ > 4 \|\| (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))
	# define ZSTD_UNREACHABLE { assert(0), __builtin_unreachable(); }
	#else
	# define ZSTD_UNREACHABLE { assert(0); }
	#endif

	/* disable warnings */

	/Like DYNAMIC_BMI2 but for compile time determination of BMI2 support/


	/* compile time determination of SIMD support */

	/* C-language Attributes are added in C23. */
	#if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
	# define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
	#else
	# define ZSTD_HAS_C_ATTRIBUTE(x) 0
	#endif

	/* Only use C++ attributes in C++. Some compilers report support for C++
	* attributes when compiling with C.
	*/
	#define ZSTD_HAS_CPP_ATTRIBUTE(x) 0

	/* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
	* - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
	* - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
	* - Else: __attribute__((__fallthrough__))
	*/
	#define ZSTD_FALLTHROUGH fallthrough

	/-*************************************************************
	* Alignment check
	*****************************************************************/

	/* this test was initially positioned in mem.h,
	* but this file is removed (or replaced) for linux kernel
	* so it's now hosted in compiler.h,
	* which remains valid for both user & kernel spaces.
	*/

	#ifndef ZSTD_ALIGNOF
	/* covers gcc, clang & MSVC */
	/* note : this section must come first, before C11,
	* due to a limitation in the kernel source generator */
	# define ZSTD_ALIGNOF(T) __alignof(T)

	#endif /* ZSTD_ALIGNOF */

	/-*************************************************************
	* Sanitizer
	*****************************************************************/



	#endif /* ZSTD_COMPILER_H */