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#ifndef OS_CPU_AIX_PPC_ATOMIC_AIX_PPC_HPP
#define OS_CPU_AIX_PPC_ATOMIC_AIX_PPC_HPP
#ifndef PPC64
#error "Atomic currently only implemented for PPC64"
#endif
#include "orderAccess_aix_ppc.hpp"
#include "utilities/debug.hpp"
// Implementation of class atomic
//
// machine barrier instructions:
//
// - sync two-way memory barrier, aka fence
// - lwsync orders Store|Store,
// Load|Store,
// Load|Load,
// but not Store|Load
// - eieio orders memory accesses for device memory (only)
// - isync invalidates speculatively executed instructions
// From the POWER ISA 2.06 documentation:
// "[...] an isync instruction prevents the execution of
// instructions following the isync until instructions
// preceding the isync have completed, [...]"
// From IBM's AIX assembler reference:
// "The isync [...] instructions causes the processor to
// refetch any instructions that might have been fetched
// prior to the isync instruction. The instruction isync
// causes the processor to wait for all previous instructions
// to complete. Then any instructions already fetched are
// discarded and instruction processing continues in the
// environment established by the previous instructions."
//
// semantic barrier instructions:
// (as defined in orderAccess.hpp)
//
// - release orders Store|Store, (maps to lwsync)
// Load|Store
// - acquire orders Load|Store, (maps to lwsync)
// Load|Load
// - fence orders Store|Store, (maps to sync)
// Load|Store,
// Load|Load,
// Store|Load
//
inline void pre_membar(atomic_memory_order order) {
switch (order) {
case memory_order_relaxed:
case memory_order_acquire: break;
case memory_order_release:
case memory_order_acq_rel: __asm__ __volatile__ ("lwsync" : : : "memory"); break;
default /*conservative*/ : __asm__ __volatile__ ("sync" : : : "memory"); break;
}
}
inline void post_membar(atomic_memory_order order) {
switch (order) {
case memory_order_relaxed:
case memory_order_release: break;
case memory_order_acquire:
case memory_order_acq_rel: __asm__ __volatile__ ("isync" : : : "memory"); break;
default /*conservative*/ : __asm__ __volatile__ ("sync" : : : "memory"); break;
}
}
template<size_t byte_size>
struct Atomic::PlatformAdd
: Atomic::AddAndFetch<Atomic::PlatformAdd<byte_size> >
{
template<typename D, typename I>
D add_and_fetch(D volatile* dest, I add_value, atomic_memory_order order) const;
};
template<>
template<typename D, typename I>
inline D Atomic::PlatformAdd<4>::add_and_fetch(D volatile* dest, I add_value,
atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(I));
STATIC_ASSERT(4 == sizeof(D));
D result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %0, 0, %2 \n"
" add %0, %0, %1 \n"
" stwcx. %0, 0, %2 \n"
" bne- 1b \n"
: /*%0*/"=&r" (result)
: /*%1*/"r" (add_value), /*%2*/"r" (dest)
: "cc", "memory" );
post_membar(order);
return result;
}
template<>
template<typename D, typename I>
inline D Atomic::PlatformAdd<8>::add_and_fetch(D volatile* dest, I add_value,
atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(I));
STATIC_ASSERT(8 == sizeof(D));
D result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %0, 0, %2 \n"
" add %0, %0, %1 \n"
" stdcx. %0, 0, %2 \n"
" bne- 1b \n"
: /*%0*/"=&r" (result)
: /*%1*/"r" (add_value), /*%2*/"r" (dest)
: "cc", "memory" );
post_membar(order);
return result;
}
template<>
template<typename T>
inline T Atomic::PlatformXchg<4>::operator()(T volatile* dest,
T exchange_value,
atomic_memory_order order) const {
// Note that xchg doesn't necessarily do an acquire
// (see synchronizer.cpp).
T old_value;
const uint64_t zero = 0;
pre_membar(order);
__asm__ __volatile__ (
/* atomic loop */
"1: \n"
" lwarx %[old_value], %[dest], %[zero] \n"
" stwcx. %[exchange_value], %[dest], %[zero] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value),
"=m" (*dest)
/* in */
: [dest] "b" (dest),
[zero] "r" (zero),
[exchange_value] "r" (exchange_value),
"m" (*dest)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<>
template<typename T>
inline T Atomic::PlatformXchg<8>::operator()(T volatile* dest,
T exchange_value,
atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
// Note that xchg doesn't necessarily do an acquire
// (see synchronizer.cpp).
T old_value;
const uint64_t zero = 0;
pre_membar(order);
__asm__ __volatile__ (
/* atomic loop */
"1: \n"
" ldarx %[old_value], %[dest], %[zero] \n"
" stdcx. %[exchange_value], %[dest], %[zero] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value),
"=m" (*dest)
/* in */
: [dest] "b" (dest),
[zero] "r" (zero),
[exchange_value] "r" (exchange_value),
"m" (*dest)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<>
template<typename T>
inline T Atomic::PlatformCmpxchg<1>::operator()(T exchange_value,
T volatile* dest,
T compare_value,
atomic_memory_order order) const {
STATIC_ASSERT(1 == sizeof(T));
// Note that cmpxchg guarantees a two-way memory barrier across
// the cmpxchg, so it's really a a 'fence_cmpxchg_fence' if not
// specified otherwise (see atomic.hpp).
// Using 32 bit internally.
volatile int *dest_base = (volatile int*)((uintptr_t)dest & ~3);
#ifdef VM_LITTLE_ENDIAN
const unsigned int shift_amount = ((uintptr_t)dest & 3) * 8;
#else
const unsigned int shift_amount = ((~(uintptr_t)dest) & 3) * 8;
#endif
const unsigned int masked_compare_val = ((unsigned int)(unsigned char)compare_value),
masked_exchange_val = ((unsigned int)(unsigned char)exchange_value),
xor_value = (masked_compare_val ^ masked_exchange_val) << shift_amount;
unsigned int old_value, value32;
pre_membar(order);
__asm__ __volatile__ (
/* simple guard */
" lbz %[old_value], 0(%[dest]) \n"
" cmpw %[masked_compare_val], %[old_value] \n"
" bne- 2f \n"
/* atomic loop */
"1: \n"
" lwarx %[value32], 0, %[dest_base] \n"
/* extract byte and compare */
" srd %[old_value], %[value32], %[shift_amount] \n"
" clrldi %[old_value], %[old_value], 56 \n"
" cmpw %[masked_compare_val], %[old_value] \n"
" bne- 2f \n"
/* replace byte and try to store */
" xor %[value32], %[xor_value], %[value32] \n"
" stwcx. %[value32], 0, %[dest_base] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value),
[value32] "=&r" (value32),
"=m" (*dest),
"=m" (*dest_base)
/* in */
: [dest] "b" (dest),
[dest_base] "b" (dest_base),
[shift_amount] "r" (shift_amount),
[masked_compare_val] "r" (masked_compare_val),
[xor_value] "r" (xor_value),
"m" (*dest),
"m" (*dest_base)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return PrimitiveConversions::cast<T>((unsigned char)old_value);
}
template<>
template<typename T>
inline T Atomic::PlatformCmpxchg<4>::operator()(T exchange_value,
T volatile* dest,
T compare_value,
atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
// Note that cmpxchg guarantees a two-way memory barrier across
// the cmpxchg, so it's really a a 'fence_cmpxchg_fence' if not
// specified otherwise (see atomic.hpp).
T old_value;
const uint64_t zero = 0;
pre_membar(order);
__asm__ __volatile__ (
/* simple guard */
" lwz %[old_value], 0(%[dest]) \n"
" cmpw %[compare_value], %[old_value] \n"
" bne- 2f \n"
/* atomic loop */
"1: \n"
" lwarx %[old_value], %[dest], %[zero] \n"
" cmpw %[compare_value], %[old_value] \n"
" bne- 2f \n"
" stwcx. %[exchange_value], %[dest], %[zero] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value),
"=m" (*dest)
/* in */
: [dest] "b" (dest),
[zero] "r" (zero),
[compare_value] "r" (compare_value),
[exchange_value] "r" (exchange_value),
"m" (*dest)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<>
template<typename T>
inline T Atomic::PlatformCmpxchg<8>::operator()(T exchange_value,
T volatile* dest,
T compare_value,
atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
// Note that cmpxchg guarantees a two-way memory barrier across
// the cmpxchg, so it's really a a 'fence_cmpxchg_fence' if not
// specified otherwise (see atomic.hpp).
T old_value;
const uint64_t zero = 0;
pre_membar(order);
__asm__ __volatile__ (
/* simple guard */
" ld %[old_value], 0(%[dest]) \n"
" cmpd %[compare_value], %[old_value] \n"
" bne- 2f \n"
/* atomic loop */
"1: \n"
" ldarx %[old_value], %[dest], %[zero] \n"
" cmpd %[compare_value], %[old_value] \n"
" bne- 2f \n"
" stdcx. %[exchange_value], %[dest], %[zero] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value),
"=m" (*dest)
/* in */
: [dest] "b" (dest),
[zero] "r" (zero),
[compare_value] "r" (compare_value),
[exchange_value] "r" (exchange_value),
"m" (*dest)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<size_t byte_size>
struct Atomic::PlatformOrderedLoad<byte_size, X_ACQUIRE> {
template <typename T>
T operator()(const volatile T* p) const {
T t = Atomic::load(p);
// Use twi-isync for load_acquire (faster than lwsync).
__asm__ __volatile__ ("twi 0,%0,0\n isync\n" : : "r" (t) : "memory");
return t;
}
};
#endif // OS_CPU_AIX_PPC_ATOMIC_AIX_PPC_HPP