mirror of https://github.com/torvalds/linux.git
290 lines
9.5 KiB
C
290 lines
9.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
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/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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#ifndef ZSTD_COMPILER_H
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#define ZSTD_COMPILER_H
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#include <linux/types.h>
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#include "portability_macros.h"
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/*-*******************************************************
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* Compiler specifics
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*********************************************************/
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/* force inlining */
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#if !defined(ZSTD_NO_INLINE)
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#if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */
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# define INLINE_KEYWORD inline
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#else
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# define INLINE_KEYWORD
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#endif
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#define FORCE_INLINE_ATTR __attribute__((always_inline))
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#else
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#define INLINE_KEYWORD
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#define FORCE_INLINE_ATTR
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#endif
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/*
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On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC).
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This explicitly marks such functions as __cdecl so that the code will still compile
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if a CC other than __cdecl has been made the default.
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*/
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#define WIN_CDECL
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/* UNUSED_ATTR tells the compiler it is okay if the function is unused. */
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#define UNUSED_ATTR __attribute__((unused))
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/*
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* FORCE_INLINE_TEMPLATE is used to define C "templates", which take constant
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* parameters. They must be inlined for the compiler to eliminate the constant
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* branches.
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*/
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#define FORCE_INLINE_TEMPLATE static INLINE_KEYWORD FORCE_INLINE_ATTR UNUSED_ATTR
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/*
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* HINT_INLINE is used to help the compiler generate better code. It is *not*
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* used for "templates", so it can be tweaked based on the compilers
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* performance.
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*
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* gcc-4.8 and gcc-4.9 have been shown to benefit from leaving off the
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* always_inline attribute.
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*
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* clang up to 5.0.0 (trunk) benefit tremendously from the always_inline
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* attribute.
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*/
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#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8 && __GNUC__ < 5
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# define HINT_INLINE static INLINE_KEYWORD
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#else
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# define HINT_INLINE FORCE_INLINE_TEMPLATE
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#endif
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/* "soft" inline :
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* The compiler is free to select if it's a good idea to inline or not.
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* The main objective is to silence compiler warnings
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* when a defined function in included but not used.
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*
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* Note : this macro is prefixed `MEM_` because it used to be provided by `mem.h` unit.
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* Updating the prefix is probably preferable, but requires a fairly large codemod,
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* since this name is used everywhere.
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*/
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#ifndef MEM_STATIC /* already defined in Linux Kernel mem.h */
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#define MEM_STATIC static __inline UNUSED_ATTR
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#endif
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/* force no inlining */
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#define FORCE_NOINLINE static __attribute__((__noinline__))
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/* target attribute */
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#define TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
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/* Target attribute for BMI2 dynamic dispatch.
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* Enable lzcnt, bmi, and bmi2.
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* We test for bmi1 & bmi2. lzcnt is included in bmi1.
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*/
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#define BMI2_TARGET_ATTRIBUTE TARGET_ATTRIBUTE("lzcnt,bmi,bmi2")
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/* prefetch
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* can be disabled, by declaring NO_PREFETCH build macro */
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#if ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )
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# define PREFETCH_L1(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 3 /* locality */)
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# define PREFETCH_L2(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)
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#elif defined(__aarch64__)
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# define PREFETCH_L1(ptr) do { __asm__ __volatile__("prfm pldl1keep, %0" ::"Q"(*(ptr))); } while (0)
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# define PREFETCH_L2(ptr) do { __asm__ __volatile__("prfm pldl2keep, %0" ::"Q"(*(ptr))); } while (0)
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#else
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# define PREFETCH_L1(ptr) do { (void)(ptr); } while (0) /* disabled */
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# define PREFETCH_L2(ptr) do { (void)(ptr); } while (0) /* disabled */
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#endif /* NO_PREFETCH */
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#define CACHELINE_SIZE 64
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#define PREFETCH_AREA(p, s) \
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do { \
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const char* const _ptr = (const char*)(p); \
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size_t const _size = (size_t)(s); \
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size_t _pos; \
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for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) { \
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PREFETCH_L2(_ptr + _pos); \
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} \
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} while (0)
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/* vectorization
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* older GCC (pre gcc-4.3 picked as the cutoff) uses a different syntax,
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* and some compilers, like Intel ICC and MCST LCC, do not support it at all. */
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#if !defined(__INTEL_COMPILER) && !defined(__clang__) && defined(__GNUC__) && !defined(__LCC__)
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# if (__GNUC__ == 4 && __GNUC_MINOR__ > 3) || (__GNUC__ >= 5)
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# define DONT_VECTORIZE __attribute__((optimize("no-tree-vectorize")))
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# else
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# define DONT_VECTORIZE _Pragma("GCC optimize(\"no-tree-vectorize\")")
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# endif
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#else
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# define DONT_VECTORIZE
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#endif
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/* Tell the compiler that a branch is likely or unlikely.
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* Only use these macros if it causes the compiler to generate better code.
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* If you can remove a LIKELY/UNLIKELY annotation without speed changes in gcc
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* and clang, please do.
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*/
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#define LIKELY(x) (__builtin_expect((x), 1))
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#define UNLIKELY(x) (__builtin_expect((x), 0))
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#if __has_builtin(__builtin_unreachable) || (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))
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# define ZSTD_UNREACHABLE do { assert(0), __builtin_unreachable(); } while (0)
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#else
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# define ZSTD_UNREACHABLE do { assert(0); } while (0)
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#endif
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/* disable warnings */
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/* compile time determination of SIMD support */
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/* C-language Attributes are added in C23. */
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#if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
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# define ZSTD_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
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#else
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# define ZSTD_HAS_C_ATTRIBUTE(x) 0
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#endif
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/* Only use C++ attributes in C++. Some compilers report support for C++
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* attributes when compiling with C.
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*/
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#define ZSTD_HAS_CPP_ATTRIBUTE(x) 0
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/* Define ZSTD_FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute.
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* - C23: https://en.cppreference.com/w/c/language/attributes/fallthrough
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* - CPP17: https://en.cppreference.com/w/cpp/language/attributes/fallthrough
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* - Else: __attribute__((__fallthrough__))
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*/
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#define ZSTD_FALLTHROUGH fallthrough
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/*-**************************************************************
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* Alignment
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*****************************************************************/
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/* @return 1 if @u is a 2^n value, 0 otherwise
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* useful to check a value is valid for alignment restrictions */
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MEM_STATIC int ZSTD_isPower2(size_t u) {
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return (u & (u-1)) == 0;
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}
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/* this test was initially positioned in mem.h,
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* but this file is removed (or replaced) for linux kernel
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* so it's now hosted in compiler.h,
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* which remains valid for both user & kernel spaces.
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*/
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#ifndef ZSTD_ALIGNOF
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/* covers gcc, clang & MSVC */
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/* note : this section must come first, before C11,
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* due to a limitation in the kernel source generator */
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# define ZSTD_ALIGNOF(T) __alignof(T)
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#endif /* ZSTD_ALIGNOF */
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#ifndef ZSTD_ALIGNED
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/* C90-compatible alignment macro (GCC/Clang). Adjust for other compilers if needed. */
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#define ZSTD_ALIGNED(a) __attribute__((aligned(a)))
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#endif /* ZSTD_ALIGNED */
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/*-**************************************************************
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* Sanitizer
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*****************************************************************/
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/*
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* Zstd relies on pointer overflow in its decompressor.
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* We add this attribute to functions that rely on pointer overflow.
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*/
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#ifndef ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
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# if __has_attribute(no_sanitize)
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# if !defined(__clang__) && defined(__GNUC__) && __GNUC__ < 8
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/* gcc < 8 only has signed-integer-overlow which triggers on pointer overflow */
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# define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR __attribute__((no_sanitize("signed-integer-overflow")))
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# else
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/* older versions of clang [3.7, 5.0) will warn that pointer-overflow is ignored. */
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# define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR __attribute__((no_sanitize("pointer-overflow")))
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# endif
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# else
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# define ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
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# endif
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#endif
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/*
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* Helper function to perform a wrapped pointer difference without triggering
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* UBSAN.
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*
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* @returns lhs - rhs with wrapping
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*/
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MEM_STATIC
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ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
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ptrdiff_t ZSTD_wrappedPtrDiff(unsigned char const* lhs, unsigned char const* rhs)
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{
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return lhs - rhs;
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}
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/*
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* Helper function to perform a wrapped pointer add without triggering UBSAN.
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*
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* @return ptr + add with wrapping
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*/
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MEM_STATIC
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ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
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unsigned char const* ZSTD_wrappedPtrAdd(unsigned char const* ptr, ptrdiff_t add)
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{
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return ptr + add;
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}
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/*
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* Helper function to perform a wrapped pointer subtraction without triggering
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* UBSAN.
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*
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* @return ptr - sub with wrapping
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*/
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MEM_STATIC
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ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
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unsigned char const* ZSTD_wrappedPtrSub(unsigned char const* ptr, ptrdiff_t sub)
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{
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return ptr - sub;
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}
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/*
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* Helper function to add to a pointer that works around C's undefined behavior
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* of adding 0 to NULL.
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*
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* @returns `ptr + add` except it defines `NULL + 0 == NULL`.
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*/
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MEM_STATIC
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unsigned char* ZSTD_maybeNullPtrAdd(unsigned char* ptr, ptrdiff_t add)
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{
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return add > 0 ? ptr + add : ptr;
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}
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/* Issue #3240 reports an ASAN failure on an llvm-mingw build. Out of an
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* abundance of caution, disable our custom poisoning on mingw. */
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#ifdef __MINGW32__
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#ifndef ZSTD_ASAN_DONT_POISON_WORKSPACE
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#define ZSTD_ASAN_DONT_POISON_WORKSPACE 1
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#endif
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#ifndef ZSTD_MSAN_DONT_POISON_WORKSPACE
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#define ZSTD_MSAN_DONT_POISON_WORKSPACE 1
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#endif
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#endif
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#endif /* ZSTD_COMPILER_H */
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