diff options
Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/config/vxlib.c')
-rw-r--r-- | gcc-4.2.1-5666.3/gcc/config/vxlib.c | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/config/vxlib.c b/gcc-4.2.1-5666.3/gcc/config/vxlib.c new file mode 100644 index 000000000..8625981a3 --- /dev/null +++ b/gcc-4.2.1-5666.3/gcc/config/vxlib.c @@ -0,0 +1,386 @@ +/* Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. + Contributed by Zack Weinberg <zack@codesourcery.com> + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 2, or (at your option) any later +version. + +GCC 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 +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING. If not, write to the Free +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +/* As a special exception, if you link this library with other files, + some of which are compiled with GCC, to produce an executable, + this library does not by itself cause the resulting executable + to be covered by the GNU General Public License. + This exception does not however invalidate any other reasons why + the executable file might be covered by the GNU General Public License. */ + +/* Threads compatibility routines for libgcc2 for VxWorks. + These are out-of-line routines called from gthr-vxworks.h. */ + +#include "tconfig.h" +#include "tsystem.h" +#include "gthr.h" + +#if defined(__GTHREADS) +#include <vxWorks.h> +#ifndef __RTP__ +#include <vxLib.h> +#endif +#include <taskLib.h> +#ifndef __RTP__ +#include <taskHookLib.h> +#else +# include <errno.h> +#endif + +/* Init-once operation. + + This would be a clone of the implementation from gthr-solaris.h, + except that we have a bootstrap problem - the whole point of this + exercise is to prevent double initialization, but if two threads + are racing with each other, once->mutex is liable to be initialized + by both. Then each thread will lock its own mutex, and proceed to + call the initialization routine. + + So instead we use a bare atomic primitive (vxTas()) to handle + mutual exclusion. Threads losing the race then busy-wait, calling + taskDelay() to yield the processor, until the initialization is + completed. Inefficient, but reliable. */ + +int +__gthread_once (__gthread_once_t *guard, void (*func)(void)) +{ + if (guard->done) + return 0; + +#ifdef __RTP__ + __gthread_lock_library (); +#else + while (!vxTas ((void *)&guard->busy)) + taskDelay (1); +#endif + + /* Only one thread at a time gets here. Check ->done again, then + go ahead and call func() if no one has done it yet. */ + if (!guard->done) + { + func (); + guard->done = 1; + } + +#ifdef __RTP__ + __gthread_unlock_library (); +#else + guard->busy = 0; +#endif + return 0; +} + +/* Thread-local storage. + + We reserve a field in the TCB to point to a dynamically allocated + array which is used to store TLS values. A TLS key is simply an + offset in this array. The exact location of the TCB field is not + known to this code nor to vxlib.c -- all access to it indirects + through the routines __gthread_get_tls_data and + __gthread_set_tls_data, which are provided by the VxWorks kernel. + + There is also a global array which records which keys are valid and + which have destructors. + + A task delete hook is installed to execute key destructors. The + routines __gthread_enter_tls_dtor_context and + __gthread_leave_tls_dtor_context, which are also provided by the + kernel, ensure that it is safe to call free() on memory allocated + by the task being deleted. (This is a no-op on VxWorks 5, but + a major undertaking on AE.) + + The task delete hook is only installed when at least one thread + has TLS data. This is a necessary precaution, to allow this module + to be unloaded - a module with a hook can not be removed. + + Since this interface is used to allocate only a small number of + keys, the table size is small and static, which simplifies the + code quite a bit. Revisit this if and when it becomes necessary. */ + +#define MAX_KEYS 4 + +/* This is the structure pointed to by the pointer returned + by __gthread_get_tls_data. */ +struct tls_data +{ + int *owner; + void *values[MAX_KEYS]; + unsigned int generation[MAX_KEYS]; +}; + +/* To make sure we only delete TLS data associated with this object, + include a pointer to a local variable in the TLS data object. */ +static int self_owner; + +/* The number of threads for this module which have active TLS data. + This is protected by tls_lock. */ +static int active_tls_threads; + +/* kernel provided routines */ +extern void *__gthread_get_tls_data (void); +extern void __gthread_set_tls_data (void *data); + +extern void __gthread_enter_tls_dtor_context (void); +extern void __gthread_leave_tls_dtor_context (void); + + +/* This is a global structure which records all of the active keys. + + A key is potentially valid (i.e. has been handed out by + __gthread_key_create) iff its generation count in this structure is + even. In that case, the matching entry in the dtors array is a + routine to be called when a thread terminates with a valid, + non-NULL specific value for that key. + + A key is actually valid in a thread T iff the generation count + stored in this structure is equal to the generation count stored in + T's specific-value structure. */ + +typedef void (*tls_dtor) (void *); + +struct tls_keys +{ + tls_dtor dtor[MAX_KEYS]; + unsigned int generation[MAX_KEYS]; +}; + +#define KEY_VALID_P(key) !(tls_keys.generation[key] & 1) + +/* Note: if MAX_KEYS is increased, this initializer must be updated + to match. All the generation counts begin at 1, which means no + key is valid. */ +static struct tls_keys tls_keys = +{ + { 0, 0, 0, 0 }, + { 1, 1, 1, 1 } +}; + +/* This lock protects the tls_keys structure. */ +static __gthread_mutex_t tls_lock; + +static __gthread_once_t tls_init_guard = __GTHREAD_ONCE_INIT; + +/* Internal routines. */ + +/* The task TCB has just been deleted. Call the destructor + function for each TLS key that has both a destructor and + a non-NULL specific value in this thread. + + This routine does not need to take tls_lock; the generation + count protects us from calling a stale destructor. It does + need to read tls_keys.dtor[key] atomically. */ + +static void +tls_delete_hook (void *tcb ATTRIBUTE_UNUSED) +{ + struct tls_data *data = __gthread_get_tls_data (); + __gthread_key_t key; + + if (data && data->owner == &self_owner) + { + __gthread_enter_tls_dtor_context (); + for (key = 0; key < MAX_KEYS; key++) + { + if (data->generation[key] == tls_keys.generation[key]) + { + tls_dtor dtor = tls_keys.dtor[key]; + + if (dtor) + dtor (data->values[key]); + } + } + free (data); + + /* We can't handle an error here, so just leave the thread + marked as loaded if one occurs. */ + if (__gthread_mutex_lock (&tls_lock) != ERROR) + { + active_tls_threads--; + if (active_tls_threads == 0) + taskDeleteHookDelete ((FUNCPTR)tls_delete_hook); + __gthread_mutex_unlock (&tls_lock); + } + + __gthread_set_tls_data (0); + __gthread_leave_tls_dtor_context (); + } +} + +/* Initialize global data used by the TLS system. */ +static void +tls_init (void) +{ + __GTHREAD_MUTEX_INIT_FUNCTION (&tls_lock); +} + +static void tls_destructor (void) __attribute__ ((destructor)); +static void +tls_destructor (void) +{ +#ifdef __RTP__ + /* All threads but this one should have exited by now. */ + tls_delete_hook (NULL); +#else + /* Unregister the hook forcibly. The counter of active threads may + be incorrect, because constructors (like the C++ library's) and + destructors (like this one) run in the context of the shell rather + than in a task spawned from this module. */ + taskDeleteHookDelete ((FUNCPTR)tls_delete_hook); +#endif + + if (tls_init_guard.done && __gthread_mutex_lock (&tls_lock) != ERROR) + semDelete (tls_lock); +} + +/* External interface */ + +/* Store in KEYP a value which can be passed to __gthread_setspecific/ + __gthread_getspecific to store and retrieve a value which is + specific to each calling thread. If DTOR is not NULL, it will be + called when a thread terminates with a non-NULL specific value for + this key, with the value as its sole argument. */ + +int +__gthread_key_create (__gthread_key_t *keyp, tls_dtor dtor) +{ + __gthread_key_t key; + + __gthread_once (&tls_init_guard, tls_init); + + if (__gthread_mutex_lock (&tls_lock) == ERROR) + return errno; + + for (key = 0; key < MAX_KEYS; key++) + if (!KEY_VALID_P (key)) + goto found_slot; + + /* no room */ + __gthread_mutex_unlock (&tls_lock); + return EAGAIN; + + found_slot: + tls_keys.generation[key]++; /* making it even */ + tls_keys.dtor[key] = dtor; + *keyp = key; + __gthread_mutex_unlock (&tls_lock); + return 0; +} + +/* Invalidate KEY; it can no longer be used as an argument to + setspecific/getspecific. Note that this does NOT call destructor + functions for any live values for this key. */ +int +__gthread_key_delete (__gthread_key_t key) +{ + if (key >= MAX_KEYS) + return EINVAL; + + __gthread_once (&tls_init_guard, tls_init); + + if (__gthread_mutex_lock (&tls_lock) == ERROR) + return errno; + + if (!KEY_VALID_P (key)) + { + __gthread_mutex_unlock (&tls_lock); + return EINVAL; + } + + tls_keys.generation[key]++; /* making it odd */ + tls_keys.dtor[key] = 0; + + __gthread_mutex_unlock (&tls_lock); + return 0; +} + +/* Retrieve the thread-specific value for KEY. If it has never been + set in this thread, or KEY is invalid, returns NULL. + + It does not matter if this function races with key_create or + key_delete; the worst that can happen is you get a value other than + the one that a serialized implementation would have provided. */ + +void * +__gthread_getspecific (__gthread_key_t key) +{ + struct tls_data *data; + + if (key >= MAX_KEYS) + return 0; + + data = __gthread_get_tls_data (); + + if (!data) + return 0; + + if (data->generation[key] != tls_keys.generation[key]) + return 0; + + return data->values[key]; +} + +/* Set the thread-specific value for KEY. If KEY is invalid, or + memory allocation fails, returns -1, otherwise 0. + + The generation count protects this function against races with + key_create/key_delete; the worst thing that can happen is that a + value is successfully stored into a dead generation (and then + immediately becomes invalid). However, we do have to make sure + to read tls_keys.generation[key] atomically. */ + +int +__gthread_setspecific (__gthread_key_t key, void *value) +{ + struct tls_data *data; + unsigned int generation; + + if (key >= MAX_KEYS) + return EINVAL; + + data = __gthread_get_tls_data (); + if (!data) + { + if (__gthread_mutex_lock (&tls_lock) == ERROR) + return ENOMEM; + if (active_tls_threads == 0) + taskDeleteHookAdd ((FUNCPTR)tls_delete_hook); + active_tls_threads++; + __gthread_mutex_unlock (&tls_lock); + + data = malloc (sizeof (struct tls_data)); + if (!data) + return ENOMEM; + + memset (data, 0, sizeof (struct tls_data)); + data->owner = &self_owner; + __gthread_set_tls_data (data); + } + + generation = tls_keys.generation[key]; + + if (generation & 1) + return EINVAL; + + data->generation[key] = generation; + data->values[key] = value; + + return 0; +} +#endif /* __GTHREADS */ |