// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file is an internal atomic implementation, use base/atomicops.h instead.
// TODO(rmcilroy): Investigate whether we can use __sync__ intrinsics instead of
// the hand coded assembly without introducing perf regressions.
// TODO(rmcilroy): Investigate whether we can use acquire / release versions of
// exclusive load / store assembly instructions and do away with
// the barriers.
#ifndef BASE_ATOMICOPS_INTERNALS_ARM64_GCC_H_
#define BASE_ATOMICOPS_INTERNALS_ARM64_GCC_H_
#if defined(OS_QNX)
#include <sys/cpuinline.h>
#endif
namespace base {
namespace subtle {
inline void MemoryBarrier() {
__asm__ __volatile__ ("dmb ish" ::: "memory"); // NOLINT
}
// NoBarrier versions of the operation include "memory" in the clobber list.
// This is not required for direct usage of the NoBarrier versions of the
// operations. However this is required for correctness when they are used as
// part of the Acquire or Release versions, to ensure that nothing from outside
// the call is reordered between the operation and the memory barrier. This does
// not change the code generated, so has no or minimal impact on the
// NoBarrier operations.
inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
Atomic32 prev;
int32_t temp;
__asm__ __volatile__ ( // NOLINT
"0: \n\t"
"ldxr %w[prev], %[ptr] \n\t" // Load the previous value.
"cmp %w[prev], %w[old_value] \n\t"
"bne 1f \n\t"
"stxr %w[temp], %w[new_value], %[ptr] \n\t" // Try to store the new value.
"cbnz %w[temp], 0b \n\t" // Retry if it did not work.
"1: \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"IJr" (old_value),
[new_value]"r" (new_value)
: "cc", "memory"
); // NOLINT
return prev;
}
inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
Atomic32 new_value) {
Atomic32 result;
int32_t temp;
__asm__ __volatile__ ( // NOLINT
"0: \n\t"
"ldxr %w[result], %[ptr] \n\t" // Load the previous value.
"stxr %w[temp], %w[new_value], %[ptr] \n\t" // Try to store the new value.
"cbnz %w[temp], 0b \n\t" // Retry if it did not work.
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [new_value]"r" (new_value)
: "memory"
); // NOLINT
return result;
}
inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
Atomic32 increment) {
Atomic32 result;
int32_t temp;
__asm__ __volatile__ ( // NOLINT
"0: \n\t"
"ldxr %w[result], %[ptr] \n\t" // Load the previous value.
"add %w[result], %w[result], %w[increment]\n\t"
"stxr %w[temp], %w[result], %[ptr] \n\t" // Try to store the result.
"cbnz %w[temp], 0b \n\t" // Retry on failure.
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [increment]"IJr" (increment)
: "memory"
); // NOLINT
return result;
}
inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
Atomic32 increment) {
MemoryBarrier();
Atomic32 result = NoBarrier_AtomicIncrement(ptr, increment);
MemoryBarrier();
return result;
}
inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
Atomic32 prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
MemoryBarrier();
return prev;
}
inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
MemoryBarrier();
Atomic32 prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
return prev;
}
inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
*ptr = value;
}
inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
*ptr = value;
MemoryBarrier();
}
inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
__asm__ __volatile__ ( // NOLINT
"stlr %w[value], %[ptr] \n\t"
: [ptr]"=Q" (*ptr)
: [value]"r" (value)
: "memory"
); // NOLINT
}
inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
return *ptr;
}
inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
Atomic32 value;
__asm__ __volatile__ ( // NOLINT
"ldar %w[value], %[ptr] \n\t"
: [value]"=r" (value)
: [ptr]"Q" (*ptr)
: "memory"
); // NOLINT
return value;
}
inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
MemoryBarrier();
return *ptr;
}
// 64-bit versions of the operations.
// See the 32-bit versions for comments.
inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
Atomic64 old_value,
Atomic64 new_value) {
Atomic64 prev;
int32_t temp;
__asm__ __volatile__ ( // NOLINT
"0: \n\t"
"ldxr %[prev], %[ptr] \n\t"
"cmp %[prev], %[old_value] \n\t"
"bne 1f \n\t"
"stxr %w[temp], %[new_value], %[ptr] \n\t"
"cbnz %w[temp], 0b \n\t"
"1: \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"IJr" (old_value),
[new_value]"r" (new_value)
: "cc", "memory"
); // NOLINT
return prev;
}
inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
Atomic64 new_value) {
Atomic64 result;
int32_t temp;
__asm__ __volatile__ ( // NOLINT
"0: \n\t"
"ldxr %[result], %[ptr] \n\t"
"stxr %w[temp], %[new_value], %[ptr] \n\t"
"cbnz %w[temp], 0b \n\t"
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [new_value]"r" (new_value)
: "memory"
); // NOLINT
return result;
}
inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
Atomic64 increment) {
Atomic64 result;
int32_t temp;
__asm__ __volatile__ ( // NOLINT
"0: \n\t"
"ldxr %[result], %[ptr] \n\t"
"add %[result], %[result], %[increment] \n\t"
"stxr %w[temp], %[result], %[ptr] \n\t"
"cbnz %w[temp], 0b \n\t"
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [increment]"IJr" (increment)
: "memory"
); // NOLINT
return result;
}
inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
Atomic64 increment) {
MemoryBarrier();
Atomic64 result = NoBarrier_AtomicIncrement(ptr, increment);
MemoryBarrier();
return result;
}
inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
Atomic64 old_value,
Atomic64 new_value) {
Atomic64 prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
MemoryBarrier();
return prev;
}
inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
Atomic64 old_value,
Atomic64 new_value) {
MemoryBarrier();
Atomic64 prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
return prev;
}
inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
*ptr = value;
}
inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
*ptr = value;
MemoryBarrier();
}
inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
__asm__ __volatile__ ( // NOLINT
"stlr %x[value], %[ptr] \n\t"
: [ptr]"=Q" (*ptr)
: [value]"r" (value)
: "memory"
); // NOLINT
}
inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
return *ptr;
}
inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
Atomic64 value;
__asm__ __volatile__ ( // NOLINT
"ldar %x[value], %[ptr] \n\t"
: [value]"=r" (value)
: [ptr]"Q" (*ptr)
: "memory"
); // NOLINT
return value;
}
inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
MemoryBarrier();
return *ptr;
}
} // namespace base::subtle
} // namespace base
#endif // BASE_ATOMICOPS_INTERNALS_ARM64_GCC_H_