New macro (GC_ALWAYS_MULTITHREADED) to set multi-threaded mode implicitly

* darwin_stop_world.c (GC_use_threads_discovery): Skip assertion on
GC_need_to_lock if GC_ALWAYS_MULTITHREADED.
* misc.c (GC_init): Likewise.
* doc/README.macros (GC_ALWAYS_MULTITHREADED): Document.
* include/gc.h (GC_allow_register_threads): Update comment (regarding
GC_ALWAYS_MULTITHREADED).
* include/private/gc_locks.h (I_HOLD_LOCK): Reformat code.
* include/private/gc_locks.h (GC_need_to_lock): Define as macro
(to TRUE) if GC_ALWAYS_MULTITHREADED defined.
* include/private/gc_locks.h (LOCK, UNLOCK): Define to UNCOND_[UN]LOCK
if GC_ALWAYS_MULTITHREADED.
* misc.c (GC_init): Call GC_init_parallel() if GC_ALWAYS_MULTITHREADED
but not GC_NO_THREADS_DISCOVERY (only for Win32, needed since
GC_allow_register_threads does nothing if GC_ALWAYS_MULTITHREADED).
* misc.c (IF_NEED_TO_LOCK): Ignore GC_parallel if
GC_ALWAYS_MULTITHREADED (since GC_need_to_lock is always true).
* pthread_support.c (GC_need_to_lock): Do not define varaible if
GC_ALWAYS_MULTITHREADED (since defined as a macro).
* win32_threads.c (GC_need_to_lock): Likewise.
* pthread_support.c (GC_allow_register_threads, pthread_create): Do
not alter value of GC_need_to_lock if GC_ALWAYS_MULTITHREADED.
* win32_threads.c (GC_allow_register_threads, GC_CreateThread,
GC_beginthreadex, GC_pthread_create, GC_init_parallel): Likewise.
* win32_threads.c (GC_allow_register_threads): Do not alter
"parallel_initialized" value if GC_ALWAYS_MULTITHREADED (so that
GC_allow_register_threads is a no-op if the macro defined).

1 files changed, 7 insertions, 3 deletions

diff --git a/misc.c b/misc.c
index c0ba6f4d..3ca8ad94 100644
--- a/misc.c
+++ b/misc.c
@@ -853,7 +853,9 @@ GC_API void GC_CALL GC_init(void)
     /* then.  Thus we really don't hold any locks, and can */
     /* in fact safely initialize them here.                */
 #   ifdef THREADS
-      GC_ASSERT(!GC_need_to_lock);
+#     ifndef GC_ALWAYS_MULTITHREADED
+        GC_ASSERT(!GC_need_to_lock);
+#     endif
 #     ifdef SN_TARGET_PS3
         {
           pthread_mutexattr_t mattr;
@@ -1214,7 +1216,9 @@ GC_API void GC_CALL GC_init(void)
 
     /* The rest of this again assumes we don't really hold      */
     /* the allocation lock.                                     */
-#   if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
+#   if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC) \
+       || (defined(GC_ALWAYS_MULTITHREADED) && defined(GC_WIN32_THREADS) \
+           && !defined(GC_NO_THREADS_DISCOVERY))
         /* Make sure marker threads are started and thread local */
         /* allocation is initialized, in case we didn't get      */
         /* called from GC_init_parallel.                         */
@@ -1293,7 +1297,7 @@ GC_API void GC_CALL GC_enable_incremental(void)
   }
 
 # ifdef THREADS
-#   ifdef PARALLEL_MARK
+#   if defined(PARALLEL_MARK) && !defined(GC_ALWAYS_MULTITHREADED)
 #     define IF_NEED_TO_LOCK(x) if (GC_parallel || GC_need_to_lock) x
 #   else
 #     define IF_NEED_TO_LOCK(x) if (GC_need_to_lock) x