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Commit d21acd91 authored by alexandre.rames@arm.com's avatar alexandre.rames@arm.com
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ARM64: Fix and improve atomic operations. 

* The 'compare and swap' operations should enforce memory ordering even when
  the exchange does not occur.

* The exclusive monitor does not need to be cleared by CLREX if a LDRX was
  not followed by a matching STREX.

* Use LDAR and STLR where possible.

* Use the 'I' and 'J' constraints to hint for constants valid for immediate
  values.

R=jfb@chromium.org, rmcilroy@chromium.org, ulan@chromium.org

Review URL: https://codereview.chromium.org/220793002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20446 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
parent 0f52462e
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Showing with 56 additions and 97 deletions
src/atomicops_internals_arm64_gcc.h
View file @ d21acd91
......@@ -34,12 +34,16 @@ namespace v8 {
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,
......@@ -55,13 +59,12 @@ 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;
......@@ -101,7 +104,7 @@ inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [increment]"r" (increment)
: [increment]"IJr" (increment)
: "memory"
); // NOLINT
......@@ -110,8 +113,10 @@ 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;
......@@ -121,27 +126,9 @@ 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;
}
......@@ -150,27 +137,9 @@ 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;
}
......@@ -185,8 +154,12 @@ 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) {
......@@ -194,8 +167,15 @@ 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;
}
......@@ -221,13 +201,12 @@ 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;
......@@ -267,7 +246,7 @@ inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
: [result]"=&r" (result),
[temp]"=&r" (temp),
[ptr]"+Q" (*ptr)
: [increment]"r" (increment)
: [increment]"IJr" (increment)
: "memory"
); // NOLINT
......@@ -276,8 +255,10 @@ 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;
......@@ -287,25 +268,9 @@ 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;
}
......@@ -314,26 +279,9 @@ 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;
}
......@@ -348,8 +296,12 @@ 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) {
......@@ -357,8 +309,15 @@ 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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