/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause *//* * Copyright (c) Meta Platforms, Inc. and affiliates. * 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 <linux/types.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 /* UNUSED_ATTR tells the compiler it is okay if the function is unused. */#define UNUSED_ATTR __attribute__((unused)) /* * 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 UNUSED_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 FORCE_INLINE_TEMPLATE#endif /* "soft" inline : * The compiler is free to select if it's a good idea to inline or not. * The main objective is to silence compiler warnings * when a defined function in included but not used. * * Note : this macro is prefixed `MEM_` because it used to be provided by `mem.h` unit. * Updating the prefix is probably preferable, but requires a fairly large codemod, * since this name is used everywhere. */#ifndef MEM_STATIC  /* already defined in Linux Kernel mem.h */#define MEM_STATIC static __inline UNUSED_ATTR#endif /* 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)  do { __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr))); } while (0)#  define PREFETCH_L2(ptr)  do { __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr))); } while (0)#else#  define PREFETCH_L1(ptr) do { (void)(ptr); } while (0)  /* disabled */#  define PREFETCH_L2(ptr) do { (void)(ptr); } while (0)  /* disabled */#endif  /* NO_PREFETCH */ #define CACHELINE_SIZE 64 #define PREFETCH_AREA(p, s)                              \    do {                                                 \        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);                    \        }                                                \    } while (0) /* 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 do { assert(0), __builtin_unreachable(); } while (0)#else#  define ZSTD_UNREACHABLE do { assert(0); } while (0)#endif /* disable warnings */ /* 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*****************************************************************/ /* @return 1 if @u is a 2^n value, 0 otherwise * useful to check a value is valid for alignment restrictions */MEM_STATIC int ZSTD_isPower2(size_t u) {    return (u & (u-1)) == 0;} /* 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 */ #ifndef ZSTD_ALIGNED/* C90-compatible alignment macro (GCC/Clang). Adjust for other compilers if needed. */#define ZSTD_ALIGNED(a) __attribute__((aligned(a)))#endif /* ZSTD_ALIGNED */  /*-***************************************************************  Sanitizer*****************************************************************/ /* * Zstd relies on pointer overflow in its decompressor. * We add this attribute to functions that rely on pointer overflow. */#ifndef ZSTD_ALLOW_POINTER_OVERFLOW_ATTR#  if __has_attribute(no_sanitize)#    if !defined(__clang__) && defined(__GNUC__) && __GNUC__ < 8       /* gcc < 8 only has signed-integer-overlow which triggers on pointer overflow */#      define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR __attribute__((no_sanitize("signed-integer-overflow")))#    else       /* older versions of clang [3.7, 5.0) will warn that pointer-overflow is ignored. */#      define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR __attribute__((no_sanitize("pointer-overflow")))#    endif#  else#    define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR#  endif#endif /* * Helper function to perform a wrapped pointer difference without triggering * UBSAN. * * @returns lhs - rhs with wrapping */MEM_STATICZSTD_ALLOW_POINTER_OVERFLOW_ATTRptrdiff_t ZSTD_wrappedPtrDiff(unsigned char const* lhs, unsigned char const* rhs){    return lhs - rhs;} /* * Helper function to perform a wrapped pointer add without triggering UBSAN. * * @return ptr + add with wrapping */MEM_STATICZSTD_ALLOW_POINTER_OVERFLOW_ATTRunsigned char const* ZSTD_wrappedPtrAdd(unsigned char const* ptr, ptrdiff_t add){    return ptr + add;} /* * Helper function to perform a wrapped pointer subtraction without triggering * UBSAN. * * @return ptr - sub with wrapping */MEM_STATICZSTD_ALLOW_POINTER_OVERFLOW_ATTRunsigned char const* ZSTD_wrappedPtrSub(unsigned char const* ptr, ptrdiff_t sub){    return ptr - sub;} /* * Helper function to add to a pointer that works around C's undefined behavior * of adding 0 to NULL. * * @returns `ptr + add` except it defines `NULL + 0 == NULL`. */MEM_STATICunsigned char* ZSTD_maybeNullPtrAdd(unsigned char* ptr, ptrdiff_t add){    return add > 0 ? ptr + add : ptr;} /* Issue #3240 reports an ASAN failure on an llvm-mingw build. Out of an * abundance of caution, disable our custom poisoning on mingw. */#ifdef __MINGW32__#ifndef ZSTD_ASAN_DONT_POISON_WORKSPACE#define ZSTD_ASAN_DONT_POISON_WORKSPACE 1#endif#ifndef ZSTD_MSAN_DONT_POISON_WORKSPACE#define ZSTD_MSAN_DONT_POISON_WORKSPACE 1#endif#endif   #endif /* ZSTD_COMPILER_H */