103 lines
2.8 KiB
C++
103 lines
2.8 KiB
C++
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/*
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* (C) Copyright 2013 Tim Blechmann
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* (C) Copyright 2013, 2020-2025 Andrey Semashev
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*/
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#ifndef BOOST_ATOMIC_THREAD_PAUSE_HPP_INCLUDED_
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#define BOOST_ATOMIC_THREAD_PAUSE_HPP_INCLUDED_
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#include <boost/atomic/detail/config.hpp>
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#if defined(_MSC_VER)
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#include <boost/atomic/detail/ops_msvc_common.hpp>
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#endif
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#include <boost/atomic/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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#if defined(_MSC_VER)
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// (sigh, shake head) _M_ARM64EC and _M_AMD64 may be defined both
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// https://learn.microsoft.com/en-us/windows/arm/arm64ec-abi
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#if defined(_M_ARM64) || defined(_M_ARM64EC)
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extern "C" void __isb(unsigned int);
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#if defined(BOOST_MSVC)
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#pragma intrinsic(__isb)
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#endif
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#elif defined(_M_ARM)
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extern "C" void __yield(void);
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#if defined(BOOST_MSVC)
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#pragma intrinsic(__yield)
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#endif
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#elif defined(_M_AMD64) || defined(_M_IX86)
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extern "C" void _mm_pause(void);
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#if defined(BOOST_MSVC)
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#pragma intrinsic(_mm_pause)
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#endif
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#endif
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#endif
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#if defined(sun) || defined(__sun)
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// Avoid including synch.h
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extern "C" void smt_pause(void);
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#endif
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namespace boost {
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namespace atomics {
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//! The function pauses for a number of CPU cycles, potentially freeing CPU resources, allowing sibling threads to progress. May be a no-op.
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BOOST_FORCEINLINE void thread_pause() noexcept
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{
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#if defined(_MSC_VER)
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BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
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#if defined(_M_ARM64) || defined(_M_ARM64EC)
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__isb(0xF); // ISB SY
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#elif defined(_M_ARM)
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__yield();
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#elif defined(_M_AMD64) || defined(_M_IX86)
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_mm_pause();
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#endif
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BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
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#elif defined(__GNUC__)
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#if defined(__i386__) || defined(__x86_64__)
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__asm__ __volatile__("pause" : : : "memory");
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#elif defined(__aarch64__)
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// https://github.com/rust-lang/rust/commit/c064b6560b7ce0adeb9bbf5d7dcf12b1acb0c807
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// https://web.archive.org/web/20231004132033/https://bugs.java.com/bugdatabase/view_bug.do?bug_id=8258604
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__asm__ __volatile__("isb" : : : "memory");
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#elif (defined(__ARM_ARCH) && __ARM_ARCH >= 8) || defined(__ARM_ARCH_8A__)
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__asm__ __volatile__("yield" : : : "memory");
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#elif (defined(__POWERPC__) || defined(__PPC__))
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__asm__ __volatile__("or 27,27,27" : : : "memory"); // yield pseudo-instruction
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#elif defined(__riscv) && (__riscv_xlen == 64)
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#if defined(__riscv_zihintpause)
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__asm__ __volatile__("pause" : : : "memory");
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#else
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// Encoding of the pause instruction
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__asm__ __volatile__ (".4byte 0x100000F" : : : "memory");
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#endif
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#elif defined(sun) || defined(__sun)
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smt_pause();
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#endif
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#elif defined(sun) || defined(__sun)
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smt_pause();
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#endif
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}
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} // namespace atomics
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} // namespace boost
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#include <boost/atomic/detail/footer.hpp>
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#endif // BOOST_ATOMIC_THREAD_PAUSE_HPP_INCLUDED_
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