diff options
Diffstat (limited to 'lib/zstd/common/compiler.h')
| -rw-r--r-- | lib/zstd/common/compiler.h | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/lib/zstd/common/compiler.h b/lib/zstd/common/compiler.h new file mode 100644 index 000000000000..dc9bd15e174e --- /dev/null +++ b/lib/zstd/common/compiler.h @@ -0,0 +1,289 @@ +/* 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_STATIC +ZSTD_ALLOW_POINTER_OVERFLOW_ATTR +ptrdiff_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_STATIC +ZSTD_ALLOW_POINTER_OVERFLOW_ATTR +unsigned 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_STATIC +ZSTD_ALLOW_POINTER_OVERFLOW_ATTR +unsigned 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_STATIC +unsigned 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 */ |