259 lines
13 KiB
C
259 lines
13 KiB
C
/*
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* Simple interface for atomic operations.
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*
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* Copyright (C) 2013 Red Hat, Inc.
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*
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* Author: Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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* See docs/atomics.txt for discussion about the guarantees each
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* atomic primitive is meant to provide.
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*/
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#ifndef QEMU_ATOMIC_H
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#define QEMU_ATOMIC_H
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#include "qemu/compiler.h"
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// we do not really support multiple CPUs, so we dont care
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#define smp_mb()
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#define smp_wmb()
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#define smp_rmb()
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#define barrier()
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/* The variable that receives the old value of an atomically-accessed
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* variable must be non-qualified, because atomic builtins return values
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* through a pointer-type argument as in __atomic_load(&var, &old, MODEL).
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*
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* This macro has to handle types smaller than int manually, because of
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* implicit promotion. int and larger types, as well as pointers, can be
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* converted to a non-qualified type just by applying a binary operator.
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*/
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#define typeof_strip_qual(expr) \
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typeof( \
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__builtin_choose_expr( \
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__builtin_types_compatible_p(typeof(expr), bool) || \
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__builtin_types_compatible_p(typeof(expr), const bool) || \
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__builtin_types_compatible_p(typeof(expr), volatile bool) || \
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__builtin_types_compatible_p(typeof(expr), const volatile bool), \
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(bool)1, \
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__builtin_choose_expr( \
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__builtin_types_compatible_p(typeof(expr), signed char) || \
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__builtin_types_compatible_p(typeof(expr), const signed char) || \
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__builtin_types_compatible_p(typeof(expr), volatile signed char) || \
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__builtin_types_compatible_p(typeof(expr), const volatile signed char), \
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(signed char)1, \
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__builtin_choose_expr( \
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__builtin_types_compatible_p(typeof(expr), unsigned char) || \
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__builtin_types_compatible_p(typeof(expr), const unsigned char) || \
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__builtin_types_compatible_p(typeof(expr), volatile unsigned char) || \
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__builtin_types_compatible_p(typeof(expr), const volatile unsigned char), \
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(unsigned char)1, \
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__builtin_choose_expr( \
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__builtin_types_compatible_p(typeof(expr), signed short) || \
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__builtin_types_compatible_p(typeof(expr), const signed short) || \
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__builtin_types_compatible_p(typeof(expr), volatile signed short) || \
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__builtin_types_compatible_p(typeof(expr), const volatile signed short), \
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(signed short)1, \
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__builtin_choose_expr( \
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__builtin_types_compatible_p(typeof(expr), unsigned short) || \
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__builtin_types_compatible_p(typeof(expr), const unsigned short) || \
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__builtin_types_compatible_p(typeof(expr), volatile unsigned short) || \
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__builtin_types_compatible_p(typeof(expr), const volatile unsigned short), \
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(unsigned short)1, \
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(expr)+0))))))
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#ifdef __ATOMIC_RELAXED
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/* For C11 atomic ops */
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/* Sanity check that the size of an atomic operation isn't "overly large".
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* Despite the fact that e.g. i686 has 64-bit atomic operations, we do not
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* want to use them because we ought not need them, and this lets us do a
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* bit of sanity checking that other 32-bit hosts might build.
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*
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* That said, we have a problem on 64-bit ILP32 hosts in that in order to
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* sync with TCG_OVERSIZED_GUEST, this must match TCG_TARGET_REG_BITS.
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* We'd prefer not want to pull in everything else TCG related, so handle
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* those few cases by hand.
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*
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* Note that x32 is fully detected with __x86_64__ + _ILP32, and that for
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* Sparc we always force the use of sparcv9 in configure. MIPS n32 (ILP32) &
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* n64 (LP64) ABIs are both detected using __mips64.
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*/
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#if defined(__x86_64__) || defined(__sparc__) || defined(__mips64)
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# define ATOMIC_REG_SIZE 8
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#else
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# define ATOMIC_REG_SIZE sizeof(void *)
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#endif
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/* Weak atomic operations prevent the compiler moving other
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* loads/stores past the atomic operation load/store. However there is
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* no explicit memory barrier for the processor.
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*
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* The C11 memory model says that variables that are accessed from
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* different threads should at least be done with __ATOMIC_RELAXED
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* primitives or the result is undefined. Generally this has little to
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* no effect on the generated code but not using the atomic primitives
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* will get flagged by sanitizers as a violation.
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*/
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#define atomic_read__nocheck(ptr) \
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__atomic_load_n(ptr, __ATOMIC_RELAXED)
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#define atomic_read(ptr) \
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({ \
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QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
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atomic_read__nocheck(ptr); \
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})
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#define atomic_set__nocheck(ptr, i) \
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__atomic_store_n(ptr, i, __ATOMIC_RELAXED)
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#define atomic_set(ptr, i) do { \
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QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
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atomic_set__nocheck(ptr, i); \
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} while(0)
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/* All the remaining operations are fully sequentially consistent */
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#define atomic_xchg__nocheck(ptr, i) ({ \
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__atomic_exchange_n(ptr, (i), __ATOMIC_SEQ_CST); \
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})
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#define atomic_xchg(ptr, i) ({ \
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QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
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atomic_xchg__nocheck(ptr, i); \
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})
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/* Returns the eventual value, failed or not */
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#define atomic_cmpxchg__nocheck(ptr, old, new) ({ \
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typeof_strip_qual(*ptr) _old = (old); \
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(void)__atomic_compare_exchange_n(ptr, &_old, new, false, \
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__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \
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_old; \
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})
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#define atomic_cmpxchg(ptr, old, new) ({ \
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QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \
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atomic_cmpxchg__nocheck(ptr, old, new); \
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})
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/* Provide shorter names for GCC atomic builtins, return old value */
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#define atomic_fetch_inc(ptr) __atomic_fetch_add(ptr, 1, __ATOMIC_SEQ_CST)
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#define atomic_fetch_dec(ptr) __atomic_fetch_sub(ptr, 1, __ATOMIC_SEQ_CST)
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#define atomic_fetch_add(ptr, n) __atomic_fetch_add(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_fetch_sub(ptr, n) __atomic_fetch_sub(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_fetch_and(ptr, n) __atomic_fetch_and(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_fetch_or(ptr, n) __atomic_fetch_or(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_fetch_xor(ptr, n) __atomic_fetch_xor(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_inc_fetch(ptr) __atomic_add_fetch(ptr, 1, __ATOMIC_SEQ_CST)
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#define atomic_dec_fetch(ptr) __atomic_sub_fetch(ptr, 1, __ATOMIC_SEQ_CST)
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#define atomic_add_fetch(ptr, n) __atomic_add_fetch(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_sub_fetch(ptr, n) __atomic_sub_fetch(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_and_fetch(ptr, n) __atomic_and_fetch(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_or_fetch(ptr, n) __atomic_or_fetch(ptr, n, __ATOMIC_SEQ_CST)
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#define atomic_xor_fetch(ptr, n) __atomic_xor_fetch(ptr, n, __ATOMIC_SEQ_CST)
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/* And even shorter names that return void. */
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#define atomic_inc(ptr) ((void) __atomic_fetch_add(ptr, 1, __ATOMIC_SEQ_CST))
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#define atomic_dec(ptr) ((void) __atomic_fetch_sub(ptr, 1, __ATOMIC_SEQ_CST))
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#define atomic_add(ptr, n) ((void) __atomic_fetch_add(ptr, n, __ATOMIC_SEQ_CST))
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#define atomic_sub(ptr, n) ((void) __atomic_fetch_sub(ptr, n, __ATOMIC_SEQ_CST))
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#define atomic_and(ptr, n) ((void) __atomic_fetch_and(ptr, n, __ATOMIC_SEQ_CST))
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#define atomic_or(ptr, n) ((void) __atomic_fetch_or(ptr, n, __ATOMIC_SEQ_CST))
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#define atomic_xor(ptr, n) ((void) __atomic_fetch_xor(ptr, n, __ATOMIC_SEQ_CST))
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#else /* __ATOMIC_RELAXED */
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#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__)
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/*
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* __sync_lock_test_and_set() is documented to be an acquire barrier only,
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* but it is a full barrier at the hardware level. Add a compiler barrier
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* to make it a full barrier also at the compiler level.
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*/
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#ifndef _MSC_VER
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#if defined(__clang__)
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#define atomic_xchg(ptr, i) __sync_swap(ptr, i)
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#else
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#define atomic_xchg(ptr, i) (__sync_lock_test_and_set(ptr, i))
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#endif
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#endif
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#endif
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/* These will only be atomic if the processor does the fetch or store
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* in a single issue memory operation
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*/
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#define atomic_read__nocheck(p) (*(__typeof__(*(p)) volatile*) (p))
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#define atomic_set__nocheck(p, i) ((*(__typeof__(*(p)) volatile*) (p)) = (i))
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#define atomic_read(ptr) atomic_read__nocheck(ptr)
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#define atomic_set(ptr, i) atomic_set__nocheck(ptr,i)
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#define atomic_xchg__nocheck atomic_xchg
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/* Provide shorter names for GCC atomic builtins. */
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#ifdef _MSC_VER
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// these return the new value (so we make it return the previous value)
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#define atomic_fetch_inc(ptr) ((InterlockedIncrement(ptr))-1)
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#define atomic_fetch_dec(ptr) ((InterlockedDecrement(ptr))+1)
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#define atomic_fetch_add(ptr, n) ((InterlockedAdd(ptr, n))-n)
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#define atomic_fetch_sub(ptr, n) ((InterlockedAdd(ptr, -n))+n)
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#define atomic_fetch_and(ptr, n) ((InterlockedAnd(ptr, n)))
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#define atomic_fetch_or(ptr, n) ((InterlockedOr(ptr, n)))
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#define atomic_fetch_xor(ptr, n) ((InterlockedXor(ptr, n)))
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#define atomic_inc_fetch(ptr) (InterlockedIncrement((long*)(ptr)))
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#define atomic_dec_fetch(ptr) (InterlockedDecrement((long*)(ptr)))
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#define atomic_add_fetch(ptr, n) (InterlockedExchangeAdd((long*)ptr, n) + n)
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#define atomic_sub_fetch(ptr, n) (InterlockedExchangeAdd((long*)ptr, n) - n)
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#define atomic_and_fetch(ptr, n) (InterlockedAnd((long*)ptr, n) & n)
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#define atomic_or_fetch(ptr, n) (InterlockedOr((long*)ptr, n) | n)
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#define atomic_xor_fetch(ptr, n) (InterlockedXor((long*)ptr, n) ^ n)
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#define atomic_cmpxchg(ptr, old, new) ((InterlockedCompareExchange(ptr, old, new)))
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#define atomic_cmpxchg__nocheck(ptr, old, new) atomic_cmpxchg(ptr, old, new)
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#define atomic_inc(ptr) ((void) InterlockedIncrement(ptr))
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#define atomic_dec(ptr) ((void) InterlockedDecrement(ptr))
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#define atomic_add(ptr, n) ((void) InterlockedAdd(ptr, n))
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#define atomic_sub(ptr, n) ((void) InterlockedAdd(ptr, -n))
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#define atomic_and(ptr, n) ((void) InterlockedAnd(ptr, n))
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#define atomic_or(ptr, n) ((void) InterlockedOr(ptr, n))
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#define atomic_xor(ptr, n) ((void) InterlockedXor(ptr, n))
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#else // GCC/clang
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// these return the previous value
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#define atomic_fetch_inc(ptr) __sync_fetch_and_add(ptr, 1)
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#define atomic_fetch_dec(ptr) __sync_fetch_and_add(ptr, -1)
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#define atomic_fetch_add(ptr, n) __sync_fetch_and_add(ptr, n)
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#define atomic_fetch_sub(ptr, n) __sync_fetch_and_sub(ptr, n)
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#define atomic_fetch_and(ptr, n) __sync_fetch_and_and(ptr, n)
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#define atomic_fetch_or(ptr, n) __sync_fetch_and_or(ptr, n)
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#define atomic_fetch_xor(ptr, n) __sync_fetch_and_xor(ptr, n)
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#define atomic_inc_fetch(ptr) __sync_add_and_fetch(ptr, 1)
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#define atomic_dec_fetch(ptr) __sync_add_and_fetch(ptr, -1)
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#define atomic_add_fetch(ptr, n) __sync_add_and_fetch(ptr, n)
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#define atomic_sub_fetch(ptr, n) __sync_sub_and_fetch(ptr, n)
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#define atomic_and_fetch(ptr, n) __sync_and_and_fetch(ptr, n)
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#define atomic_or_fetch(ptr, n) __sync_or_and_fetch(ptr, n)
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#define atomic_xor_fetch(ptr, n) __sync_xor_and_fetch(ptr, n)
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#define atomic_cmpxchg(ptr, old, new) __sync_val_compare_and_swap(ptr, old, new)
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#define atomic_cmpxchg__nocheck(ptr, old, new) atomic_cmpxchg(ptr, old, new)
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#define atomic_inc(ptr) ((void) __sync_fetch_and_add(ptr, 1))
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#define atomic_dec(ptr) ((void) __sync_fetch_and_add(ptr, -1))
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#define atomic_add(ptr, n) ((void) __sync_fetch_and_add(ptr, n))
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#define atomic_sub(ptr, n) ((void) __sync_fetch_and_sub(ptr, n))
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#define atomic_and(ptr, n) ((void) __sync_fetch_and_and(ptr, n))
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#define atomic_or(ptr, n) ((void) __sync_fetch_and_or(ptr, n))
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#define atomic_xor(ptr, n) ((void) __sync_fetch_and_xor(ptr, n))
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#endif
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#endif /* __ATOMIC_RELAXED */
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#endif /* QEMU_ATOMIC_H */
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