| /* |
| * 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 GC_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(GC_PTHREADS) && !defined(GC_SOLARIS_THREADS) \ |
| && !defined(GC_IRIX_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 /* GC_PTHREADS with linux_threads.c implementation */ |
| # if defined(GC_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 /* GC_IRIX_THREADS */ |
| # ifdef GC_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 */ |
