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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/sysdep/pa/locks.h | |
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Diffstat (limited to 'libjava/sysdep/pa/locks.h')
-rw-r--r-- | libjava/sysdep/pa/locks.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/libjava/sysdep/pa/locks.h b/libjava/sysdep/pa/locks.h new file mode 100644 index 000000000..4edc2d716 --- /dev/null +++ b/libjava/sysdep/pa/locks.h @@ -0,0 +1,110 @@ +// locks.h - Thread synchronization primitives. PA-RISC implementation. + +/* Copyright (C) 2002, 2005 Free Software Foundation + + This file is part of libgcj. + +This software is copyrighted work licensed under the terms of the +Libgcj License. Please consult the file "LIBGCJ_LICENSE" for +details. */ + +#ifndef __SYSDEP_LOCKS_H__ +#define __SYSDEP_LOCKS_H__ + +// Integer type big enough for object address. +typedef size_t obj_addr_t; + +template<int _Inst> + struct _pa_jv_cas_lock + { + static volatile int _S_pa_jv_cas_lock; + }; + +template<int _Inst> +volatile int +_pa_jv_cas_lock<_Inst>::_S_pa_jv_cas_lock __attribute__ ((aligned (16))) = 1; + +// Because of the lack of weak support when using the hpux som +// linker, we explicitly instantiate the atomicity lock. +template volatile int _pa_jv_cas_lock<0>::_S_pa_jv_cas_lock; + +// Atomically replace *addr by new_val if it was initially equal to old_val. +// Return true if the comparison is successful. +// Assumed to have acquire semantics, i.e. later memory operations +// cannot execute before the compare_and_swap finishes. +// The following implementation is atomic but it can deadlock +// (e.g., if a thread dies holding the lock). +inline static bool +__attribute__ ((__unused__)) +compare_and_swap(volatile obj_addr_t *addr, + obj_addr_t old_val, + obj_addr_t new_val) +{ + bool result; + int tmp; + volatile int& lock = _pa_jv_cas_lock<0>::_S_pa_jv_cas_lock; + + __asm__ __volatile__ ("ldcw 0(%1),%0\n\t" + "cmpib,<>,n 0,%0,.+20\n\t" + "ldw 0(%1),%0\n\t" + "cmpib,= 0,%0,.-4\n\t" + "nop\n\t" + "b,n .-20" + : "=&r" (tmp) + : "r" (&lock) + : "memory"); + + if (*addr != old_val) + result = false; + else + { + *addr = new_val; + result = true; + } + + /* Reset lock with PA 2.0 "ordered" store. */ + __asm__ __volatile__ ("stw,ma %1,0(%0)" + : : "r" (&lock), "r" (tmp) : "memory"); + + return result; +} + +// Set *addr to new_val with release semantics, i.e. making sure +// that prior loads and stores complete before this +// assignment. +inline static void +release_set(volatile obj_addr_t *addr, obj_addr_t new_val) +{ + __asm__ __volatile__(" " : : : "memory"); + *(addr) = new_val; +} + +// Compare_and_swap with release semantics instead of acquire semantics. +// On many architecture, the operation makes both guarantees, so the +// implementation can be the same. +inline static bool +compare_and_swap_release(volatile obj_addr_t *addr, + obj_addr_t old, + obj_addr_t new_val) +{ + return compare_and_swap(addr, old, new_val); +} + +// Ensure that subsequent instructions do not execute on stale +// data that was loaded from memory before the barrier. +inline static void +read_barrier() +{ + __asm__ __volatile__(" " : : : "memory"); +} + +// Ensure that prior stores to memory are completed with respect to other +// processors. +inline static void +write_barrier() +{ + __asm__ __volatile__(" " : : : "memory"); +} + +#endif + |