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jdk/src/hotspot/cpu/ppc/atomicAccess_ppc.hpp
David Briemann c9cbd31f85 8307495: Specialize atomic bitset functions for aix-ppc 
Reviewed-by: mdoerr, rrich
2025-10-15 18:29:23 +00:00

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/*
* Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2025 SAP SE. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef CPU_PPC_ATOMICACCESS_PPC_HPP
#define CPU_PPC_ATOMICACCESS_PPC_HPP
#ifndef PPC64
#error "Atomic currently only implemented for PPC64"
#endif
#include "orderAccess_ppc.hpp"
#include "utilities/debug.hpp"
// Implementation of class AtomicAccess
//
// 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 AtomicAccess::PlatformAdd {
template<typename D, typename I>
D add_then_fetch(D volatile* dest, I add_value, atomic_memory_order order) const;
template<typename D, typename I>
D fetch_then_add(D volatile* dest, I add_value, atomic_memory_order order) const {
return add_then_fetch(dest, add_value, order) - add_value;
}
};
template<>
template<typename D, typename I>
inline D AtomicAccess::PlatformAdd<4>::add_then_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 %[result], 0, %[dest] \n"
" add %[result], %[result], %[add_value] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [add_value] "r" (add_value),
[dest] "b" (dest)
: "cc", "memory" );
post_membar(order);
return result;
}
template<>
template<typename D, typename I>
inline D AtomicAccess::PlatformAdd<8>::add_then_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 %[result], 0, %[dest] \n"
" add %[result], %[result], %[add_value] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [add_value] "r" (add_value),
[dest] "b" (dest)
: "cc", "memory" );
post_membar(order);
return result;
}
template<>
template<typename T>
inline T AtomicAccess::PlatformXchg<4>::operator()(T volatile* dest,
T exchange_value,
atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
// Note that xchg doesn't necessarily do an acquire
// (see synchronizer.cpp).
T old_value;
pre_membar(order);
__asm__ __volatile__ (
/* atomic loop */
"1: \n"
" lwarx %[old_value], 0, %[dest] \n"
" stwcx. %[exchange_value], 0, %[dest] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value)
/* in */
: [dest] "b" (dest),
[exchange_value] "r" (exchange_value)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<>
template<typename T>
inline T AtomicAccess::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;
pre_membar(order);
__asm__ __volatile__ (
/* atomic loop */
"1: \n"
" ldarx %[old_value], 0, %[dest] \n"
" stdcx. %[exchange_value], 0, %[dest] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value)
/* in */
: [dest] "b" (dest),
[exchange_value] "r" (exchange_value)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<>
template<typename T>
inline T AtomicAccess::PlatformCmpxchg<1>::operator()(T volatile* dest,
T compare_value,
T exchange_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 'fence_cmpxchg_fence' if not
// specified otherwise (see atomicAccess.hpp).
const unsigned int masked_compare_val = (unsigned int)(unsigned char)compare_value;
unsigned int old_value;
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"
" lbarx %[old_value], 0, %[dest] \n"
" cmpw %[masked_compare_val], %[old_value] \n"
" bne- 2f \n"
" stbcx. %[exchange_value], 0, %[dest] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value)
/* in */
: [dest] "b" (dest),
[masked_compare_val] "r" (masked_compare_val),
[exchange_value] "r" (exchange_value)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return PrimitiveConversions::cast<T>((unsigned char)old_value);
}
template<>
template<typename T>
inline T AtomicAccess::PlatformCmpxchg<4>::operator()(T volatile* dest,
T compare_value,
T exchange_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 'fence_cmpxchg_fence' if not
// specified otherwise (see atomicAccess.hpp).
T old_value;
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], 0, %[dest] \n"
" cmpw %[compare_value], %[old_value] \n"
" bne- 2f \n"
" stwcx. %[exchange_value], 0, %[dest] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value)
/* in */
: [dest] "b" (dest),
[compare_value] "r" (compare_value),
[exchange_value] "r" (exchange_value)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<>
template<typename T>
inline T AtomicAccess::PlatformCmpxchg<8>::operator()(T volatile* dest,
T compare_value,
T exchange_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 'fence_cmpxchg_fence' if not
// specified otherwise (see atomicAccess.hpp).
T old_value;
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], 0, %[dest] \n"
" cmpd %[compare_value], %[old_value] \n"
" bne- 2f \n"
" stdcx. %[exchange_value], 0, %[dest] \n"
" bne- 1b \n"
/* exit */
"2: \n"
/* out */
: [old_value] "=&r" (old_value)
/* in */
: [dest] "b" (dest),
[compare_value] "r" (compare_value),
[exchange_value] "r" (exchange_value)
/* clobber */
: "cc",
"memory"
);
post_membar(order);
return old_value;
}
template<size_t byte_size>
struct AtomicAccess::PlatformOrderedLoad<byte_size, X_ACQUIRE>
{
template <typename T>
T operator()(const volatile T* p) const {
T t = AtomicAccess::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;
}
};
template<>
class AtomicAccess::PlatformBitops<4, true> {
public:
template<typename T>
T fetch_then_and(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
T old_value, result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %[old_value], 0, %[dest] \n"
" and %[result], %[old_value], %[bits] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [old_value] "=&r" (old_value),
[result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return old_value;
}
template<typename T>
T fetch_then_or(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
T old_value, result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %[old_value], 0, %[dest] \n"
" or %[result], %[old_value], %[bits] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [old_value] "=&r" (old_value),
[result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return old_value;
}
template<typename T>
T fetch_then_xor(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
T old_value, result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %[old_value], 0, %[dest] \n"
" xor %[result], %[old_value], %[bits] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [old_value] "=&r" (old_value),
[result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return old_value;
}
template<typename T>
T and_then_fetch(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
T result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %[result], 0, %[dest] \n"
" and %[result], %[result], %[bits] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return result;
}
template<typename T>
T or_then_fetch(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
T result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %[result], 0, %[dest] \n"
" or %[result], %[result], %[bits] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return result;
}
template<typename T>
T xor_then_fetch(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(4 == sizeof(T));
T result;
pre_membar(order);
__asm__ __volatile__ (
"1: lwarx %[result], 0, %[dest] \n"
" xor %[result], %[result], %[bits] \n"
" stwcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return result;
}
};
template<>
class AtomicAccess::PlatformBitops<8, true> {
public:
template<typename T>
T fetch_then_and(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
T old_value, result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %[old_value], 0, %[dest] \n"
" and %[result], %[old_value], %[bits] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [old_value] "=&r" (old_value),
[result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return old_value;
}
template<typename T>
T fetch_then_or(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
T old_value, result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %[old_value], 0, %[dest] \n"
" or %[result], %[old_value], %[bits] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [old_value] "=&r" (old_value),
[result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return old_value;
}
template<typename T>
T fetch_then_xor(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
T old_value, result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %[old_value], 0, %[dest] \n"
" xor %[result], %[old_value], %[bits] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [old_value] "=&r" (old_value),
[result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return old_value;
}
template<typename T>
T and_then_fetch(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
T result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %[result], 0, %[dest] \n"
" and %[result], %[result], %[bits] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return result;
}
template<typename T>
T or_then_fetch(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
T result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %[result], 0, %[dest] \n"
" or %[result], %[result], %[bits] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return result;
}
template<typename T>
T xor_then_fetch(T volatile* dest, T bits, atomic_memory_order order) const {
STATIC_ASSERT(8 == sizeof(T));
T result;
pre_membar(order);
__asm__ __volatile__ (
"1: ldarx %[result], 0, %[dest] \n"
" xor %[result], %[result], %[bits] \n"
" stdcx. %[result], 0, %[dest] \n"
" bne- 1b \n"
: [result] "=&r" (result)
: [dest] "b" (dest),
[bits] "r" (bits)
: "cc", "memory" );
post_membar(order);
return result;
}
};
#endif // CPU_PPC_ATOMICACCESS_PPC_HPP
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