5206d59712
The various atomic operations are declared as inline in the header files
to cut the function call overhead. However, the plain inline keyword is
just a suggestion to the compiler which makes its own decision on whether
to inline them or not. Worst, if they are not inlined, the
-fvisibility-inlines-hidden compiler flag will render them as hidden
symbols in the object file. If they are picked up by the linker over the
ones supplied in libcutils.so the following warning will be reported:
warning: hidden symbol 'android_atomic_inc' in foo.o is referenced by
DSO bar.so
One way is to add __attribute__((visibility("default"))) to those inline
functions to suppress the linker warnings. A better way is to force
inlining as with this patch.
Change-Id: Ie4fcfdfaaf06f42d351619a0d89671a9df15ca2f
153 lines
4.1 KiB
C
153 lines
4.1 KiB
C
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_CUTILS_ATOMIC_X86_H
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#define ANDROID_CUTILS_ATOMIC_X86_H
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#include <stdint.h>
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#ifndef ANDROID_ATOMIC_INLINE
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#define ANDROID_ATOMIC_INLINE inline __attribute__((always_inline))
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#endif
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extern ANDROID_ATOMIC_INLINE void android_compiler_barrier(void)
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{
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__asm__ __volatile__ ("" : : : "memory");
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}
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#if ANDROID_SMP == 0
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extern ANDROID_ATOMIC_INLINE void android_memory_barrier(void)
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{
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android_compiler_barrier();
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}
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extern ANDROID_ATOMIC_INLINE void android_memory_store_barrier(void)
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{
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android_compiler_barrier();
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}
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#else
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extern ANDROID_ATOMIC_INLINE void android_memory_barrier(void)
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{
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__asm__ __volatile__ ("mfence" : : : "memory");
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}
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extern ANDROID_ATOMIC_INLINE void android_memory_store_barrier(void)
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{
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android_compiler_barrier();
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}
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#endif
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_acquire_load(volatile const int32_t *ptr)
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{
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int32_t value = *ptr;
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android_compiler_barrier();
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return value;
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}
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_release_load(volatile const int32_t *ptr)
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{
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android_memory_barrier();
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return *ptr;
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}
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extern ANDROID_ATOMIC_INLINE void
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android_atomic_acquire_store(int32_t value, volatile int32_t *ptr)
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{
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*ptr = value;
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android_memory_barrier();
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}
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extern ANDROID_ATOMIC_INLINE void
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android_atomic_release_store(int32_t value, volatile int32_t *ptr)
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{
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android_compiler_barrier();
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*ptr = value;
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}
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extern ANDROID_ATOMIC_INLINE int
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android_atomic_cas(int32_t old_value, int32_t new_value, volatile int32_t *ptr)
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{
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int32_t prev;
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__asm__ __volatile__ ("lock; cmpxchgl %1, %2"
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: "=a" (prev)
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: "q" (new_value), "m" (*ptr), "0" (old_value)
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: "memory");
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return prev != old_value;
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}
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extern ANDROID_ATOMIC_INLINE int
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android_atomic_acquire_cas(int32_t old_value,
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int32_t new_value,
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volatile int32_t *ptr)
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{
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/* Loads are not reordered with other loads. */
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return android_atomic_cas(old_value, new_value, ptr);
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}
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extern ANDROID_ATOMIC_INLINE int
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android_atomic_release_cas(int32_t old_value,
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int32_t new_value,
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volatile int32_t *ptr)
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{
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/* Stores are not reordered with other stores. */
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return android_atomic_cas(old_value, new_value, ptr);
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}
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_add(int32_t increment, volatile int32_t *ptr)
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{
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__asm__ __volatile__ ("lock; xaddl %0, %1"
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: "+r" (increment), "+m" (*ptr)
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: : "memory");
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/* increment now holds the old value of *ptr */
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return increment;
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}
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_inc(volatile int32_t *addr)
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{
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return android_atomic_add(1, addr);
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}
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_dec(volatile int32_t *addr)
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{
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return android_atomic_add(-1, addr);
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}
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_and(int32_t value, volatile int32_t *ptr)
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{
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int32_t prev, status;
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do {
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prev = *ptr;
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status = android_atomic_cas(prev, prev & value, ptr);
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} while (__builtin_expect(status != 0, 0));
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return prev;
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}
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extern ANDROID_ATOMIC_INLINE int32_t
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android_atomic_or(int32_t value, volatile int32_t *ptr)
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{
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int32_t prev, status;
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do {
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prev = *ptr;
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status = android_atomic_cas(prev, prev | value, ptr);
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} while (__builtin_expect(status != 0, 0));
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return prev;
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}
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#endif /* ANDROID_CUTILS_ATOMIC_X86_H */
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