X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=rts%2Fsm%2FMarkWeak.c;h=f9275ecb62c44003ea01b0ee1ce5f46d2aa9e403;hp=7b7187c94d58e10392ec52c71fd18e41386b4691;hb=6cec61d14a324285dbb8ce73d4c7215f1f8d6766;hpb=852154bd9501f491b5499013e90922686850c833 diff --git a/rts/sm/MarkWeak.c b/rts/sm/MarkWeak.c index 7b7187c..f9275ec 100644 --- a/rts/sm/MarkWeak.c +++ b/rts/sm/MarkWeak.c @@ -17,11 +17,13 @@ #include "MarkWeak.h" #include "GC.h" #include "GCThread.h" +#include "GCTDecl.h" #include "Evac.h" #include "Trace.h" #include "Schedule.h" #include "Weak.h" #include "Storage.h" +#include "Threads.h" /* ----------------------------------------------------------------------------- Weak Pointers @@ -80,9 +82,6 @@ StgWeak *old_weak_ptr_list; // also pending finaliser list // List of threads found to be unreachable StgTSO *resurrected_threads; -// List of blocked threads found to have pending throwTos -StgTSO *exception_threads; - static void resurrectUnreachableThreads (generation *gen); static rtsBool tidyThreadList (generation *gen); @@ -93,7 +92,6 @@ initWeakForGC(void) weak_ptr_list = NULL; weak_stage = WeakPtrs; resurrected_threads = END_TSO_QUEUE; - exception_threads = END_TSO_QUEUE; } rtsBool @@ -113,7 +111,7 @@ traverseWeakPtrList(void) /* doesn't matter where we evacuate values/finalizers to, since * these pointers are treated as roots (iff the keys are alive). */ - gct->evac_gen = 0; + gct->evac_gen_no = 0; last_w = &old_weak_ptr_list; for (w = old_weak_ptr_list; w != NULL; w = next_w) { @@ -213,21 +211,6 @@ traverseWeakPtrList(void) } } - /* Finally, we can update the blackhole_queue. This queue - * simply strings together TSOs blocked on black holes, it is - * not intended to keep anything alive. Hence, we do not follow - * pointers on the blackhole_queue until now, when we have - * determined which TSOs are otherwise reachable. We know at - * this point that all TSOs have been evacuated, however. - */ - { - StgTSO **pt; - for (pt = &blackhole_queue; *pt != END_TSO_QUEUE; pt = &((*pt)->_link)) { - *pt = (StgTSO *)isAlive((StgClosure *)*pt); - ASSERT(*pt != NULL); - } - } - weak_stage = WeakDone; // *now* we're done, return rtsTrue; // but one more round of scavenging, please } @@ -278,43 +261,16 @@ static rtsBool tidyThreadList (generation *gen) } ASSERT(get_itbl(t)->type == TSO); - if (t->what_next == ThreadRelocated) { - next = t->_link; - *prev = next; - continue; - } - next = t->global_link; - // This is a good place to check for blocked - // exceptions. It might be the case that a thread is - // blocked on delivering an exception to a thread that - // is also blocked - we try to ensure that this - // doesn't happen in throwTo(), but it's too hard (or - // impossible) to close all the race holes, so we - // accept that some might get through and deal with - // them here. A GC will always happen at some point, - // even if the system is otherwise deadlocked. - // - // If an unreachable thread has blocked - // exceptions, we really want to perform the - // blocked exceptions rather than throwing - // BlockedIndefinitely exceptions. This is the - // only place we can discover such threads. - // The target thread might even be - // ThreadFinished or ThreadKilled. Bugs here - // will only be seen when running on a - // multiprocessor. - if (t->blocked_exceptions != END_TSO_QUEUE) { - if (tmp == NULL) { - evacuate((StgClosure **)&t); - flag = rtsTrue; - } - t->global_link = exception_threads; - exception_threads = t; - *prev = next; - continue; - } + // if the thread is not masking exceptions but there are + // pending exceptions on its queue, then something has gone + // wrong. However, pending exceptions are OK if there is an + // FFI call. + ASSERT(t->blocked_exceptions == END_BLOCKED_EXCEPTIONS_QUEUE + || t->why_blocked == BlockedOnCCall + || t->why_blocked == BlockedOnCCall_Interruptible + || (t->flags & TSO_BLOCKEX)); if (tmp == NULL) { // not alive (yet): leave this thread on the @@ -337,49 +293,6 @@ static rtsBool tidyThreadList (generation *gen) } /* ----------------------------------------------------------------------------- - The blackhole queue - - Threads on this list behave like weak pointers during the normal - phase of garbage collection: if the blackhole is reachable, then - the thread is reachable too. - -------------------------------------------------------------------------- */ -rtsBool -traverseBlackholeQueue (void) -{ - StgTSO *prev, *t, *tmp; - rtsBool flag; - nat type; - - flag = rtsFalse; - prev = NULL; - - for (t = blackhole_queue; t != END_TSO_QUEUE; prev=t, t = t->_link) { - // if the thread is not yet alive... - if (! (tmp = (StgTSO *)isAlive((StgClosure*)t))) { - // if the closure it is blocked on is either (a) a - // reachable BLAKCHOLE or (b) not a BLACKHOLE, then we - // make the thread alive. - if (!isAlive(t->block_info.closure)) { - type = get_itbl(t->block_info.closure)->type; - if (type == BLACKHOLE || type == CAF_BLACKHOLE) { - continue; - } - } - evacuate((StgClosure **)&t); - if (prev) { - prev->_link = t; - } else { - blackhole_queue = t; - } - // no write barrier when on the blackhole queue, - // because we traverse the whole queue on every GC. - flag = rtsTrue; - } - } - return flag; -} - -/* ----------------------------------------------------------------------------- Evacuate every weak pointer object on the weak_ptr_list, and update the link fields. @@ -395,9 +308,18 @@ markWeakPtrList ( void ) last_w = &weak_ptr_list; for (w = weak_ptr_list; w; w = w->link) { // w might be WEAK, EVACUATED, or DEAD_WEAK (actually CON_STATIC) here - ASSERT(IS_FORWARDING_PTR(w->header.info) - || w->header.info == &stg_DEAD_WEAK_info - || get_itbl(w)->type == WEAK); + +#ifdef DEBUG + { // careful to do this assertion only reading the info ptr + // once, because during parallel GC it might change under our feet. + const StgInfoTable *info; + info = w->header.info; + ASSERT(IS_FORWARDING_PTR(info) + || info == &stg_DEAD_WEAK_info + || INFO_PTR_TO_STRUCT(info)->type == WEAK); + } +#endif + evacuate((StgClosure **)last_w); w = *last_w; if (w->header.info == &stg_DEAD_WEAK_info) {