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| -rw-r--r-- | gc/include/private/gc_locks.h | 481 |
1 files changed, 481 insertions, 0 deletions
diff --git a/gc/include/private/gc_locks.h b/gc/include/private/gc_locks.h new file mode 100644 index 0000000..eed9f10 --- /dev/null +++ b/gc/include/private/gc_locks.h @@ -0,0 +1,481 @@ +/* + * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers + * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved. + * Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved. + * Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved. + * + * + * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED + * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. + * + * Permission is hereby granted to use or copy this program + * for any purpose, provided the above notices are retained on all copies. + * Permission to modify the code and to distribute modified code is granted, + * provided the above notices are retained, and a notice that the code was + * modified is included with the above copyright notice. + */ + +#ifndef GC_LOCKS_H +#define GC_LOCKS_H + +/* + * Mutual exclusion between allocator/collector routines. + * Needed if there is more than one allocator thread. + * FASTLOCK() is assumed to try to acquire the lock in a cheap and + * dirty way that is acceptable for a few instructions, e.g. by + * inhibiting preemption. This is assumed to have succeeded only + * if a subsequent call to FASTLOCK_SUCCEEDED() returns TRUE. + * FASTUNLOCK() is called whether or not FASTLOCK_SUCCEEDED(). + * If signals cannot be tolerated with the FASTLOCK held, then + * FASTLOCK should disable signals. The code executed under + * FASTLOCK is otherwise immune to interruption, provided it is + * not restarted. + * DCL_LOCK_STATE declares any local variables needed by LOCK and UNLOCK + * and/or DISABLE_SIGNALS and ENABLE_SIGNALS and/or FASTLOCK. + * (There is currently no equivalent for FASTLOCK.) + * + * In the PARALLEL_MARK case, we also need to define a number of + * other inline finctions here: + * GC_bool GC_compare_and_exchange( volatile GC_word *addr, + * GC_word old, GC_word new ) + * GC_word GC_atomic_add( volatile GC_word *addr, GC_word how_much ) + * void GC_memory_barrier( ) + * + */ +# ifdef THREADS + void GC_noop1 GC_PROTO((word)); +# ifdef PCR_OBSOLETE /* Faster, but broken with multiple lwp's */ +# include "th/PCR_Th.h" +# include "th/PCR_ThCrSec.h" + extern struct PCR_Th_MLRep GC_allocate_ml; +# define DCL_LOCK_STATE PCR_sigset_t GC_old_sig_mask +# define LOCK() PCR_Th_ML_Acquire(&GC_allocate_ml) +# define UNLOCK() PCR_Th_ML_Release(&GC_allocate_ml) +# define UNLOCK() PCR_Th_ML_Release(&GC_allocate_ml) +# define FASTLOCK() PCR_ThCrSec_EnterSys() + /* Here we cheat (a lot): */ +# define FASTLOCK_SUCCEEDED() (*(int *)(&GC_allocate_ml) == 0) + /* TRUE if nobody currently holds the lock */ +# define FASTUNLOCK() PCR_ThCrSec_ExitSys() +# endif +# ifdef PCR +# include <base/PCR_Base.h> +# include <th/PCR_Th.h> + extern PCR_Th_ML GC_allocate_ml; +# define DCL_LOCK_STATE \ + PCR_ERes GC_fastLockRes; PCR_sigset_t GC_old_sig_mask +# define LOCK() PCR_Th_ML_Acquire(&GC_allocate_ml) +# define UNLOCK() PCR_Th_ML_Release(&GC_allocate_ml) +# define FASTLOCK() (GC_fastLockRes = PCR_Th_ML_Try(&GC_allocate_ml)) +# define FASTLOCK_SUCCEEDED() (GC_fastLockRes == PCR_ERes_okay) +# define FASTUNLOCK() {\ + if( FASTLOCK_SUCCEEDED() ) PCR_Th_ML_Release(&GC_allocate_ml); } +# endif +# ifdef SRC_M3 + extern GC_word RT0u__inCritical; +# define LOCK() RT0u__inCritical++ +# define UNLOCK() RT0u__inCritical-- +# endif +# ifdef SOLARIS_THREADS +# include <thread.h> +# include <signal.h> + extern mutex_t GC_allocate_ml; +# define LOCK() mutex_lock(&GC_allocate_ml); +# define UNLOCK() mutex_unlock(&GC_allocate_ml); +# endif + +/* Try to define GC_TEST_AND_SET and a matching GC_CLEAR for spin lock */ +/* acquisition and release. We need this for correct operation of the */ +/* incremental GC. */ +# ifdef __GNUC__ +# if defined(I386) + inline static int GC_test_and_set(volatile unsigned int *addr) { + int oldval; + /* Note: the "xchg" instruction does not need a "lock" prefix */ + __asm__ __volatile__("xchgl %0, %1" + : "=r"(oldval), "=m"(*(addr)) + : "0"(1), "m"(*(addr)) : "memory"); + return oldval; + } +# define GC_TEST_AND_SET_DEFINED +# endif +# if defined(IA64) + inline static int GC_test_and_set(volatile unsigned int *addr) { + long oldval, n = 1; + __asm__ __volatile__("xchg4 %0=%1,%2" + : "=r"(oldval), "=m"(*addr) + : "r"(n), "1"(*addr) : "memory"); + return oldval; + } +# define GC_TEST_AND_SET_DEFINED + /* Should this handle post-increment addressing?? */ + inline static void GC_clear(volatile unsigned int *addr) { + __asm__ __volatile__("st4.rel %0=r0" : "=m" (*addr) : : "memory"); + } +# define GC_CLEAR_DEFINED +# endif +# ifdef SPARC + inline static int GC_test_and_set(volatile unsigned int *addr) { + int oldval; + + __asm__ __volatile__("ldstub %1,%0" + : "=r"(oldval), "=m"(*addr) + : "m"(*addr) : "memory"); + return oldval; + } +# define GC_TEST_AND_SET_DEFINED +# endif +# ifdef M68K + /* Contributed by Tony Mantler. I'm not sure how well it was */ + /* tested. */ + inline static int GC_test_and_set(volatile unsigned int *addr) { + char oldval; /* this must be no longer than 8 bits */ + + /* The return value is semi-phony. */ + /* 'tas' sets bit 7 while the return */ + /* value pretends bit 0 was set */ + __asm__ __volatile__( + "tas %1@; sne %0; negb %0" + : "=d" (oldval) + : "a" (addr) : "memory"); + return oldval; + } +# define GC_TEST_AND_SET_DEFINED +# endif +# if defined(POWERPC) + inline static int GC_test_and_set(volatile unsigned int *addr) { + int oldval; + int temp = 1; // locked value + + __asm__ __volatile__( + "1:\tlwarx %0,0,%3\n" // load and reserve + "\tcmpwi %0, 0\n" // if load is + "\tbne 2f\n" // non-zero, return already set + "\tstwcx. %2,0,%1\n" // else store conditional + "\tbne- 1b\n" // retry if lost reservation + "2:\t\n" // oldval is zero if we set + : "=&r"(oldval), "=p"(addr) + : "r"(temp), "1"(addr) + : "memory"); + return (int)oldval; + } +# define GC_TEST_AND_SET_DEFINED + inline static void GC_clear(volatile unsigned int *addr) { + __asm__ __volatile__("eieio" ::: "memory"); + *(addr) = 0; + } +# define GC_CLEAR_DEFINED +# endif +# if defined(ALPHA) + inline static int GC_test_and_set(volatile unsigned int * addr) + { + unsigned long oldvalue; + unsigned long temp; + + __asm__ __volatile__( + "1: ldl_l %0,%1\n" + " and %0,%3,%2\n" + " bne %2,2f\n" + " xor %0,%3,%0\n" + " stl_c %0,%1\n" + " beq %0,3f\n" + " mb\n" + "2:\n" + ".section .text2,\"ax\"\n" + "3: br 1b\n" + ".previous" + :"=&r" (temp), "=m" (*addr), "=&r" (oldvalue) + :"Ir" (1), "m" (*addr) + :"memory"); + + return oldvalue; + } +# define GC_TEST_AND_SET_DEFINED + /* Should probably also define GC_clear, since it needs */ + /* a memory barrier ?? */ +# endif /* ALPHA */ +# ifdef ARM32 + inline static int GC_test_and_set(volatile unsigned int *addr) { + int oldval; + /* SWP on ARM is very similar to XCHG on x86. Doesn't lock the + * bus because there are no SMP ARM machines. If/when there are, + * this code will likely need to be updated. */ + /* See linuxthreads/sysdeps/arm/pt-machine.h in glibc-2.1 */ + __asm__ __volatile__("swp %0, %1, [%2]" + : "=r"(oldval) + : "r"(1), "r"(addr) + : "memory"); + return oldval; + } +# define GC_TEST_AND_SET_DEFINED +# endif /* ARM32 */ +# endif /* __GNUC__ */ +# if (defined(ALPHA) && !defined(__GNUC__)) +# define GC_test_and_set(addr) __cxx_test_and_set_atomic(addr, 1) +# define GC_TEST_AND_SET_DEFINED +# endif +# if defined(MSWIN32) +# define GC_test_and_set(addr) InterlockedExchange((LPLONG)addr,1) +# define GC_TEST_AND_SET_DEFINED +# endif +# ifdef MIPS +# if __mips < 3 || !(defined (_ABIN32) || defined(_ABI64)) \ + || !defined(_COMPILER_VERSION) || _COMPILER_VERSION < 700 +# define GC_test_and_set(addr, v) test_and_set(addr,v) +# else +# define GC_test_and_set(addr, v) __test_and_set(addr,v) +# define GC_clear(addr) __lock_release(addr); +# define GC_CLEAR_DEFINED +# endif +# define GC_TEST_AND_SET_DEFINED +# endif /* MIPS */ +# if 0 /* defined(HP_PA) */ + /* The official recommendation seems to be to not use ldcw from */ + /* user mode. Since multithreaded incremental collection doesn't */ + /* work anyway on HP_PA, this shouldn't be a major loss. */ + + /* "set" means 0 and "clear" means 1 here. */ +# define GC_test_and_set(addr) !GC_test_and_clear(addr); +# define GC_TEST_AND_SET_DEFINED +# define GC_clear(addr) GC_noop1((word)(addr)); *(volatile unsigned int *)addr = 1; + /* The above needs a memory barrier! */ +# define GC_CLEAR_DEFINED +# endif +# if defined(GC_TEST_AND_SET_DEFINED) && !defined(GC_CLEAR_DEFINED) +# ifdef __GNUC__ + inline static void GC_clear(volatile unsigned int *addr) { + /* Try to discourage gcc from moving anything past this. */ + __asm__ __volatile__(" " : : : "memory"); + *(addr) = 0; + } +# else + /* The function call in the following should prevent the */ + /* compiler from moving assignments to below the UNLOCK. */ +# define GC_clear(addr) GC_noop1((word)(addr)); \ + *((volatile unsigned int *)(addr)) = 0; +# endif +# define GC_CLEAR_DEFINED +# endif /* !GC_CLEAR_DEFINED */ + +# if !defined(GC_TEST_AND_SET_DEFINED) +# define USE_PTHREAD_LOCKS +# endif + +# if defined(LINUX_THREADS) || defined(OSF1_THREADS) \ + || defined(HPUX_THREADS) +# define NO_THREAD (pthread_t)(-1) +# include <pthread.h> +# if defined(PARALLEL_MARK) + /* We need compare-and-swap to update mark bits, where it's */ + /* performance critical. If USE_MARK_BYTES is defined, it is */ + /* no longer needed for this purpose. However we use it in */ + /* either case to implement atomic fetch-and-add, though that's */ + /* less performance critical, and could perhaps be done with */ + /* a lock. */ +# if defined(GENERIC_COMPARE_AND_SWAP) + /* Probably not useful, except for debugging. */ + /* We do use GENERIC_COMPARE_AND_SWAP on PA_RISC, but we */ + /* minimize its use. */ + extern pthread_mutex_t GC_compare_and_swap_lock; + + /* Note that if GC_word updates are not atomic, a concurrent */ + /* reader should acquire GC_compare_and_swap_lock. On */ + /* currently supported platforms, such updates are atomic. */ + extern GC_bool GC_compare_and_exchange(volatile GC_word *addr, + GC_word old, GC_word new_val); +# endif /* GENERIC_COMPARE_AND_SWAP */ +# if defined(I386) +# if !defined(GENERIC_COMPARE_AND_SWAP) + /* Returns TRUE if the comparison succeeded. */ + inline static GC_bool GC_compare_and_exchange(volatile GC_word *addr, + GC_word old, + GC_word new_val) + { + char result; + __asm__ __volatile__("lock; cmpxchgl %2, %0; setz %1" + : "=m"(*(addr)), "=r"(result) + : "r" (new_val), "0"(*(addr)), "a"(old) : "memory"); + return (GC_bool) result; + } +# endif /* !GENERIC_COMPARE_AND_SWAP */ + inline static void GC_memory_write_barrier() + { + /* We believe the processor ensures at least processor */ + /* consistent ordering. Thus a compiler barrier */ + /* should suffice. */ + __asm__ __volatile__("" : : : "memory"); + } +# endif /* I386 */ +# if defined(IA64) +# if !defined(GENERIC_COMPARE_AND_SWAP) + inline static GC_bool GC_compare_and_exchange(volatile GC_word *addr, + GC_word old, GC_word new_val) + { + unsigned long oldval; + __asm__ __volatile__("mov ar.ccv=%4 ;; cmpxchg8.rel %0=%1,%2,ar.ccv" + : "=r"(oldval), "=m"(*addr) + : "r"(new_val), "1"(*addr), "r"(old) : "memory"); + return (oldval == old); + } +# endif /* !GENERIC_COMPARE_AND_SWAP */ +# if 0 + /* Shouldn't be needed; we use volatile stores instead. */ + inline static void GC_memory_write_barrier() + { + __asm__ __volatile__("mf" : : : "memory"); + } +# endif /* 0 */ +# endif /* IA64 */ +# if !defined(GENERIC_COMPARE_AND_SWAP) + /* Returns the original value of *addr. */ + inline static GC_word GC_atomic_add(volatile GC_word *addr, + GC_word how_much) + { + GC_word old; + do { + old = *addr; + } while (!GC_compare_and_exchange(addr, old, old+how_much)); + return old; + } +# else /* GENERIC_COMPARE_AND_SWAP */ + /* So long as a GC_word can be atomically updated, it should */ + /* be OK to read *addr without a lock. */ + extern GC_word GC_atomic_add(volatile GC_word *addr, GC_word how_much); +# endif /* GENERIC_COMPARE_AND_SWAP */ + +# endif /* PARALLEL_MARK */ + +# if !defined(THREAD_LOCAL_ALLOC) && !defined(USE_PTHREAD_LOCKS) + /* In the THREAD_LOCAL_ALLOC case, the allocation lock tends to */ + /* be held for long periods, if it is held at all. Thus spinning */ + /* and sleeping for fixed periods are likely to result in */ + /* significant wasted time. We thus rely mostly on queued locks. */ +# define USE_SPIN_LOCK + extern volatile unsigned int GC_allocate_lock; + extern void GC_lock(void); + /* Allocation lock holder. Only set if acquired by client through */ + /* GC_call_with_alloc_lock. */ +# ifdef GC_ASSERTIONS +# define LOCK() \ + { if (GC_test_and_set(&GC_allocate_lock)) GC_lock(); \ + SET_LOCK_HOLDER(); } +# define UNLOCK() \ + { GC_ASSERT(I_HOLD_LOCK()); UNSET_LOCK_HOLDER(); \ + GC_clear(&GC_allocate_lock); } +# else +# define LOCK() \ + { if (GC_test_and_set(&GC_allocate_lock)) GC_lock(); } +# define UNLOCK() \ + GC_clear(&GC_allocate_lock) +# endif /* !GC_ASSERTIONS */ +# if 0 + /* Another alternative for OSF1 might be: */ +# include <sys/mman.h> + extern msemaphore GC_allocate_semaphore; +# define LOCK() { if (msem_lock(&GC_allocate_semaphore, MSEM_IF_NOWAIT) \ + != 0) GC_lock(); else GC_allocate_lock = 1; } + /* The following is INCORRECT, since the memory model is too weak. */ + /* Is this true? Presumably msem_unlock has the right semantics? */ + /* - HB */ +# define UNLOCK() { GC_allocate_lock = 0; \ + msem_unlock(&GC_allocate_semaphore, 0); } +# endif /* 0 */ +# else /* THREAD_LOCAL_ALLOC || USE_PTHREAD_LOCKS */ +# ifndef USE_PTHREAD_LOCKS +# define USE_PTHREAD_LOCKS +# endif +# endif /* THREAD_LOCAL_ALLOC */ +# ifdef USE_PTHREAD_LOCKS +# include <pthread.h> + extern pthread_mutex_t GC_allocate_ml; +# ifdef GC_ASSERTIONS +# define LOCK() \ + { GC_lock(); \ + SET_LOCK_HOLDER(); } +# define UNLOCK() \ + { GC_ASSERT(I_HOLD_LOCK()); UNSET_LOCK_HOLDER(); \ + pthread_mutex_unlock(&GC_allocate_ml); } +# else /* !GC_ASSERTIONS */ +# define LOCK() \ + { if (0 != pthread_mutex_trylock(&GC_allocate_ml)) GC_lock(); } +# define UNLOCK() pthread_mutex_unlock(&GC_allocate_ml) +# endif /* !GC_ASSERTIONS */ +# endif /* USE_PTHREAD_LOCKS */ +# define SET_LOCK_HOLDER() GC_lock_holder = pthread_self() +# define UNSET_LOCK_HOLDER() GC_lock_holder = NO_THREAD +# define I_HOLD_LOCK() (pthread_equal(GC_lock_holder, pthread_self())) + extern VOLATILE GC_bool GC_collecting; +# define ENTER_GC() GC_collecting = 1; +# define EXIT_GC() GC_collecting = 0; + extern void GC_lock(void); + extern pthread_t GC_lock_holder; +# ifdef GC_ASSERTIONS + extern pthread_t GC_mark_lock_holder; +# endif +# endif /* LINUX_THREADS || OSF1_THREADS || HPUX_THREADS */ +# if defined(IRIX_THREADS) +# include <pthread.h> + /* This probably should never be included, but I can't test */ + /* on Irix anymore. */ +# include <mutex.h> + + extern unsigned long GC_allocate_lock; + /* This is not a mutex because mutexes that obey the (optional) */ + /* POSIX scheduling rules are subject to convoys in high contention */ + /* applications. This is basically a spin lock. */ + extern pthread_t GC_lock_holder; + extern void GC_lock(void); + /* Allocation lock holder. Only set if acquired by client through */ + /* GC_call_with_alloc_lock. */ +# define SET_LOCK_HOLDER() GC_lock_holder = pthread_self() +# define NO_THREAD (pthread_t)(-1) +# define UNSET_LOCK_HOLDER() GC_lock_holder = NO_THREAD +# define I_HOLD_LOCK() (pthread_equal(GC_lock_holder, pthread_self())) +# define LOCK() { if (GC_test_and_set(&GC_allocate_lock, 1)) GC_lock(); } +# define UNLOCK() GC_clear(&GC_allocate_lock); + extern VOLATILE GC_bool GC_collecting; +# define ENTER_GC() \ + { \ + GC_collecting = 1; \ + } +# define EXIT_GC() GC_collecting = 0; +# endif /* IRIX_THREADS */ +# ifdef WIN32_THREADS +# include <windows.h> + GC_API CRITICAL_SECTION GC_allocate_ml; +# define LOCK() EnterCriticalSection(&GC_allocate_ml); +# define UNLOCK() LeaveCriticalSection(&GC_allocate_ml); +# endif +# ifndef SET_LOCK_HOLDER +# define SET_LOCK_HOLDER() +# define UNSET_LOCK_HOLDER() +# define I_HOLD_LOCK() FALSE + /* Used on platforms were locks can be reacquired, */ + /* so it doesn't matter if we lie. */ +# endif +# else /* !THREADS */ +# define LOCK() +# define UNLOCK() +# endif /* !THREADS */ +# ifndef SET_LOCK_HOLDER +# define SET_LOCK_HOLDER() +# define UNSET_LOCK_HOLDER() +# define I_HOLD_LOCK() FALSE + /* Used on platforms were locks can be reacquired, */ + /* so it doesn't matter if we lie. */ +# endif +# ifndef ENTER_GC +# define ENTER_GC() +# define EXIT_GC() +# endif + +# ifndef DCL_LOCK_STATE +# define DCL_LOCK_STATE +# endif +# ifndef FASTLOCK +# define FASTLOCK() LOCK() +# define FASTLOCK_SUCCEEDED() TRUE +# define FASTUNLOCK() UNLOCK() +# endif + +#endif /* GC_LOCKS_H */ |