Commit ebaff0a8 authored by Simon Marlow's avatar Simon Marlow
Browse files

more fixes for THUNK_SELECTORs

parent 797dca87
......@@ -169,6 +169,9 @@ unchain_thunk_selectors(StgSelector *p, StgClosure *val)
#else
ASSERT(p->header.info == &stg_BLACKHOLE_info);
#endif
// val must be in to-space.
ASSERT(Bdescr((P_)val)->gen_no > N || (Bdescr((P_)val)->flags & BF_EVACUATED));
prev = (StgSelector*)((StgClosure *)p)->payload[0];
// Update the THUNK_SELECTOR with an indirection to the
......@@ -177,8 +180,9 @@ unchain_thunk_selectors(StgSelector *p, StgClosure *val)
// EVACUATED closure always points to an object in the
// same or an older generation (required by the short-cut
// test in the EVACUATED case, below).
SET_INFO(p, &stg_IND_info);
((StgInd *)p)->indirectee = val;
write_barrier();
SET_INFO(p, &stg_IND_info);
// For the purposes of LDV profiling, we have created an
// indirection.
......@@ -243,16 +247,26 @@ selector_chain:
// In threaded mode, we'll use WHITEHOLE to lock the selector
// thunk while we evaluate it.
{
info_ptr = xchg((StgPtr)&p->header.info, (W_)&stg_WHITEHOLE_info);
if (info_ptr == (W_)&stg_WHITEHOLE_info) {
do {
info_ptr = xchg((StgPtr)&p->header.info, (W_)&stg_WHITEHOLE_info);
} while (info_ptr == (W_)&stg_WHITEHOLE_info);
goto bale_out;
}
// make sure someone else didn't get here first
do {
info_ptr = xchg((StgPtr)&p->header.info, (W_)&stg_WHITEHOLE_info);
} while (info_ptr == (W_)&stg_WHITEHOLE_info);
// make sure someone else didn't get here first...
if (INFO_PTR_TO_STRUCT(info_ptr)->type != THUNK_SELECTOR) {
goto bale_out;
// v. tricky now. The THUNK_SELECTOR has been evacuated
// by another thread, and is now either EVACUATED or IND.
// We need to extract ourselves from the current situation
// as cleanly as possible.
// - unlock the closure
// - update *q, we may have done *some* evaluation
// - if evac, we need to call evacuate(), because we
// need the write-barrier stuff.
// - undo the chain we've built to point to p.
SET_INFO(p, (const StgInfoTable *)info_ptr);
*q = (StgClosure *)p;
if (evac) evacuate(q);
unchain_thunk_selectors(prev_thunk_selector, (StgClosure *)p);
return;
}
}
#else
......@@ -404,6 +418,9 @@ bale_out:
// We didn't manage to evaluate this thunk; restore the old info
// pointer. But don't forget: we still need to evacuate the thunk itself.
SET_INFO(p, (const StgInfoTable *)info_ptr);
// THREADED_RTS: we just unlocked the thunk, so another thread
// might get in and update it. copy() will lock it again and
// check whether it was updated in the meantime.
*q = (StgClosure *)p;
if (evac) {
copy(q,(StgClosure *)p,THUNK_SELECTOR_sizeW(),bd->step->to);
......
......@@ -34,7 +34,9 @@ copy_tag(StgClosure **p, StgClosure *src, nat size, step *stp, StgWord tag)
info = xchg((StgPtr)&src->header.info, (W_)&stg_WHITEHOLE_info);
// so.. what is it?
} while (info == (W_)&stg_WHITEHOLE_info);
if (info == (W_)&stg_EVACUATED_info) {
if (info == (W_)&stg_EVACUATED_info || info == (W_)&stg_IND_info) {
// NB. a closure might be updated with an IND by
// unchain_selector_thunks(), hence the test above.
src->header.info = (const StgInfoTable *)info;
return evacuate(p); // does the failed_to_evac stuff
}
......
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