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Commit 0a16d839 authored by Carl Shapiro's avatar Carl Shapiro
Browse files

Remove unconditional swap from the android atomic operations suite. 

Bug: 3381237
Change-Id: I7bdc7c8eb4c1cc6303d96e40ca2f196a007c4dd2
parent 88af5ff4

include/cutils/atomic-arm.h

+0 −32
Original line number Diff line number Diff line
@@ -145,38 +145,6 @@ extern inline int android_atomic_release_cas(int32_t old_value, 
}





#if defined(__thumb__)

extern int32_t android_atomic_swap(int32_t new_value,

                                   volatile int32_t *ptr);

#elif defined(__ARM_HAVE_LDREX_STREX)

extern inline int32_t android_atomic_swap(int32_t new_value,

                                          volatile int32_t *ptr)

{

    int32_t prev, status;

    do {

        __asm__ __volatile__ ("ldrex %0, [%3]\n"

                              "strex %1, %4, [%3]"

                              : "=&r" (prev), "=&r" (status), "+m" (*ptr)

                              : "r" (ptr), "r" (new_value)

                              : "cc");

    } while (__builtin_expect(status != 0, 0));

    android_memory_barrier();

    return prev;

}

#else

extern inline int32_t android_atomic_swap(int32_t new_value,

                                          volatile int32_t *ptr)

{

    int32_t prev;

    __asm__ __volatile__ ("swp %0, %2, [%3]"

                          : "=&r" (prev), "+m" (*ptr)

                          : "r" (new_value), "r" (ptr)

                          : "cc");

    android_memory_barrier();

    return prev;

}

#endif



#if defined(__thumb__)

extern int32_t android_atomic_add(int32_t increment,

                                  volatile int32_t *ptr);

include/cutils/atomic-x86.h

+0 −11
Original line number Diff line number Diff line
@@ -98,17 +98,6 @@ extern inline int android_atomic_release_cas(int32_t old_value, 
    return android_atomic_cas(old_value, new_value, ptr);

}



extern inline int32_t android_atomic_swap(int32_t new_value,

                                          volatile int32_t *ptr)

{

    __asm__ __volatile__ ("xchgl %1, %0"

                          : "=r" (new_value)

                          : "m" (*ptr), "0" (new_value)

                          : "memory");

    /* new_value now holds the old value of *ptr */

    return new_value;

}



extern inline int32_t android_atomic_add(int32_t increment,

                                         volatile int32_t *ptr)

{

include/cutils/atomic.h

+0 −7
Original line number Diff line number Diff line
@@ -89,13 +89,6 @@ int32_t android_atomic_release_load(volatile const int32_t* addr); 
void android_atomic_acquire_store(int32_t value, volatile int32_t* addr);

void android_atomic_release_store(int32_t value, volatile int32_t* addr);



/*

 * Unconditional swap operation with release ordering.

 *

 * Stores the new value at *addr, and returns the previous value.

 */

int32_t android_atomic_swap(int32_t value, volatile int32_t* addr);



/*

 * Compare-and-set operation with "acquire" or "release" ordering.

 *

libcutils/atomic-android-sh.c

+0 −12
Original line number Diff line number Diff line
@@ -113,18 +113,6 @@ int32_t android_atomic_or(int32_t value, volatile int32_t* addr) { 
    return oldValue;

}



int32_t android_atomic_acquire_swap(int32_t value, volatile int32_t* addr) {

    return android_atomic_release_swap(value, addr);

}



int32_t android_atomic_release_swap(int32_t value, volatile int32_t* addr) {

    int32_t oldValue;

    do {

        oldValue = *addr;

    } while (android_atomic_cmpxchg(oldValue, value, addr));

    return oldValue;

}



int android_atomic_acquire_cmpxchg(int32_t oldvalue, int32_t newvalue,

                           volatile int32_t* addr) {

    return android_atomic_release_cmpxchg(oldValue, newValue, addr);