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Commit 3aa5ea95 authored by xiaofeng@google.com's avatar xiaofeng@google.com
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Fix and improve arm64 atomic operations in protobuf stubs (patch from rmcilroy@). 

https://codereview.appspot.com/86030044/
parent 2ca19bd8
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Showing with 56 additions and 97 deletions
src/google/protobuf/stubs/atomicops_internals_arm64_gcc.h
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......@@ -38,12 +38,16 @@ namespace protobuf {
namespace internal {
inline void MemoryBarrier() {
__asm__ __volatile__ ( // NOLINT
"dmb ish \n\t" // Data memory barrier.
::: "memory"
); // NOLINT
__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,
......@@ -59,13 +63,12 @@ inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
"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"
"clrex \n\t" // In case we didn't swap.
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"r" (old_value),
: [old_value]"IJr" (old_value),
[new_value]"r" (new_value)
: "memory", "cc"
: "cc", "memory"
); // NOLINT
return prev;
......@@ -105,7 +108,7 @@ inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [increment]"r" (increment)
: [increment]"IJr" (increment)
: "memory"
); // NOLINT
......@@ -114,8 +117,10 @@ inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
Atomic32 increment) {
Atomic32 result;
MemoryBarrier();
Atomic32 result = NoBarrier_AtomicIncrement(ptr, increment);
result = NoBarrier_AtomicIncrement(ptr, increment);
MemoryBarrier();
return result;
......@@ -125,27 +130,9 @@ inline Atomic32 Acquire_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.
"dmb ish \n\t" // Data memory barrier.
"1: \n\t"
// If the compare failed the 'dmb' is unnecessary, but we still need a
// 'clrex'.
"clrex \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"r" (old_value),
[new_value]"r" (new_value)
: "memory", "cc"
); // NOLINT
prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
MemoryBarrier();
return prev;
}
......@@ -154,27 +141,9 @@ inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value,
Atomic32 new_value) {
Atomic32 prev;
int32_t temp;
MemoryBarrier();
__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"
// If the compare failed the we still need a 'clrex'.
"clrex \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"r" (old_value),
[new_value]"r" (new_value)
: "memory", "cc"
); // NOLINT
prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
return prev;
}
......@@ -189,8 +158,12 @@ inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
}
inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
MemoryBarrier();
*ptr = 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) {
......@@ -198,8 +171,15 @@ inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
}
inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
Atomic32 value = *ptr;
MemoryBarrier();
Atomic32 value;
__asm__ __volatile__ ( // NOLINT
"ldar %w[value], %[ptr] \n\t"
: [value]"=r" (value)
: [ptr]"Q" (*ptr)
: "memory"
); // NOLINT
return value;
}
......@@ -225,13 +205,12 @@ inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
"stxr %w[temp], %[new_value], %[ptr] \n\t"
"cbnz %w[temp], 0b \n\t"
"1: \n\t"
"clrex \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"r" (old_value),
: [old_value]"IJr" (old_value),
[new_value]"r" (new_value)
: "memory", "cc"
: "cc", "memory"
); // NOLINT
return prev;
......@@ -271,7 +250,7 @@ inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [increment]"r" (increment)
: [increment]"IJr" (increment)
: "memory"
); // NOLINT
......@@ -280,8 +259,10 @@ inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
Atomic64 increment) {
Atomic64 result;
MemoryBarrier();
Atomic64 result = NoBarrier_AtomicIncrement(ptr, increment);
result = NoBarrier_AtomicIncrement(ptr, increment);
MemoryBarrier();
return result;
......@@ -291,25 +272,9 @@ inline Atomic64 Acquire_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"
"dmb ish \n\t"
"1: \n\t"
"clrex \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"r" (old_value),
[new_value]"r" (new_value)
: "memory", "cc"
); // NOLINT
prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
MemoryBarrier();
return prev;
}
......@@ -318,26 +283,9 @@ inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
Atomic64 old_value,
Atomic64 new_value) {
Atomic64 prev;
int32_t temp;
MemoryBarrier();
__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"
"clrex \n\t"
: [prev]"=&r" (prev),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [old_value]"r" (old_value),
[new_value]"r" (new_value)
: "memory", "cc"
); // NOLINT
prev = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
return prev;
}
......@@ -352,8 +300,12 @@ inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
}
inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
MemoryBarrier();
*ptr = 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) {
......@@ -361,8 +313,15 @@ inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
}
inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
Atomic64 value = *ptr;
MemoryBarrier();
Atomic32 value;
__asm__ __volatile__ ( // NOLINT
"ldar %x[value], %[ptr] \n\t"
: [value]"=r" (value)
: [ptr]"Q" (*ptr)
: "memory"
); // NOLINT
return value;
}
......
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