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8319883: Zero: Use atomic built-ins for 64-bit accesses

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Reviewed-by: dholmes, kbarrett, stuefe
This commit is contained in:
Aleksey Shipilev 2023-11-14 12:52:49 +00:00
parent 9c98270737
commit 25f9af99be
2 changed files with 15 additions and 63 deletions
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28
src/hotspot/os_cpu/bsd_zero/atomic_bsd_zero.hpp
View File

@ -286,31 +286,19 @@ inline T Atomic::PlatformCmpxchg<8>::operator()(T volatile* dest,
}
// Atomically copy 64 bits of data
static void atomic_copy64(const volatile void *src, volatile void *dst) {
#if defined(PPC32)
double tmp;
asm volatile ("lfd %0, 0(%1)\n"
"stfd %0, 0(%2)\n"
: "=f"(tmp)
: "b"(src), "b"(dst));
#elif defined(S390) && !defined(_LP64)
double tmp;
asm volatile ("ld %0, 0(%1)\n"
"std %0, 0(%2)\n"
: "=r"(tmp)
: "a"(src), "a"(dst));
#else
*(jlong *) dst = *(const jlong *) src;
#endif
inline void atomic_copy64(const volatile void *src, volatile void *dst) {
int64_t tmp;
__atomic_load(reinterpret_cast<const volatile int64_t*>(src), &tmp, __ATOMIC_RELAXED);
__atomic_store(reinterpret_cast<volatile int64_t*>(dst), &tmp, __ATOMIC_RELAXED);
}
template<>
template<typename T>
inline T Atomic::PlatformLoad<8>::operator()(T const volatile* src) const {
STATIC_ASSERT(8 == sizeof(T));
volatile int64_t dest;
atomic_copy64(reinterpret_cast<const volatile int64_t*>(src), reinterpret_cast<volatile int64_t*>(&dest));
return PrimitiveConversions::cast<T>(dest);
T dest;
__atomic_load(const_cast<T*>(src), &dest, __ATOMIC_RELAXED);
return dest;
}
template<>
@ -318,7 +306,7 @@ template<typename T>
inline void Atomic::PlatformStore<8>::operator()(T volatile* dest,
T store_value) const {
STATIC_ASSERT(8 == sizeof(T));
atomic_copy64(reinterpret_cast<const volatile int64_t*>(&store_value), reinterpret_cast<volatile int64_t*>(dest));
__atomic_store(dest, &store_value, __ATOMIC_RELAXED);
}
#endif // OS_CPU_BSD_ZERO_ATOMIC_BSD_ZERO_HPP

50
src/hotspot/os_cpu/linux_zero/atomic_linux_zero.hpp
View File

@ -134,54 +134,18 @@ inline T Atomic::PlatformCmpxchg<8>::operator()(T volatile* dest,
// Atomically copy 64 bits of data
inline void atomic_copy64(const volatile void *src, volatile void *dst) {
#if defined(PPC32) && !defined(__SPE__)
double tmp;
asm volatile ("lfd %0, %2\n"
"stfd %0, %1\n"
: "=&f"(tmp), "=Q"(*(volatile double*)dst)
: "Q"(*(volatile double*)src));
#elif defined(PPC32) && defined(__SPE__)
long tmp;
asm volatile ("evldd %0, %2\n"
"evstdd %0, %1\n"
: "=&r"(tmp), "=Q"(*(volatile long*)dst)
: "Q"(*(volatile long*)src));
#elif defined(S390) && !defined(_LP64)
double tmp;
asm volatile ("ld %0, %2\n"
"std %0, %1\n"
: "=&f"(tmp), "=Q"(*(volatile double*)dst)
: "Q"(*(volatile double*)src));
#elif defined(__ARM_ARCH_7A__)
// The only way to perform the atomic 64-bit load/store
// is to use ldrexd/strexd for both reads and writes.
// For store, we need to have the matching (fake) load first.
// Put clrex between exclusive ops on src and dst for clarity.
uint64_t tmp_r, tmp_w;
uint32_t flag_w;
asm volatile ("ldrexd %[tmp_r], [%[src]]\n"
"clrex\n"
"1:\n"
"ldrexd %[tmp_w], [%[dst]]\n"
"strexd %[flag_w], %[tmp_r], [%[dst]]\n"
"cmp %[flag_w], 0\n"
"bne 1b\n"
: [tmp_r] "=&r" (tmp_r), [tmp_w] "=&r" (tmp_w),
[flag_w] "=&r" (flag_w)
: [src] "r" (src), [dst] "r" (dst)
: "cc", "memory");
#else
*(jlong *) dst = *(const jlong *) src;
#endif
int64_t tmp;
__atomic_load(reinterpret_cast<const volatile int64_t*>(src), &tmp, __ATOMIC_RELAXED);
__atomic_store(reinterpret_cast<volatile int64_t*>(dst), &tmp, __ATOMIC_RELAXED);
}
template<>
template<typename T>
inline T Atomic::PlatformLoad<8>::operator()(T const volatile* src) const {
STATIC_ASSERT(8 == sizeof(T));
volatile int64_t dest;
atomic_copy64(reinterpret_cast<const volatile int64_t*>(src), reinterpret_cast<volatile int64_t*>(&dest));
return PrimitiveConversions::cast<T>(dest);
T dest;
__atomic_load(const_cast<T*>(src), &dest, __ATOMIC_RELAXED);
return dest;
}
template<>
@ -189,7 +153,7 @@ template<typename T>
inline void Atomic::PlatformStore<8>::operator()(T volatile* dest,
T store_value) const {
STATIC_ASSERT(8 == sizeof(T));
atomic_copy64(reinterpret_cast<const volatile int64_t*>(&store_value), reinterpret_cast<volatile int64_t*>(dest));
__atomic_store(dest, &store_value, __ATOMIC_RELAXED);
}
#endif // OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP