1 /* -----------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2004
7 * ---------------------------------------------------------------------------*/
16 /* -----------------------------------------------------------------------------
19 We have two layers of update macros. The top layer, UPD_IND() and
20 friends perform all the work of an update. In detail:
22 - if the closure being updated is a blocking queue, then all the
23 threads waiting on the blocking queue are updated.
25 - then the lower level updateWithIndirection() macro is invoked
26 to actually replace the closure with an indirection (see below).
28 -------------------------------------------------------------------------- */
31 # define UPD_IND(updclosure, heapptr) \
32 UPD_REAL_IND(updclosure,INFO_PTR(stg_IND_info),heapptr,SEMI)
33 # define UPD_SPEC_IND(updclosure, ind_info, heapptr, and_then) \
34 UPD_REAL_IND(updclosure,ind_info,heapptr,and_then)
36 /* These macros have to work in both C and C--, so here's the
42 #define INFO_PTR(info) info
46 #define INFO_PTR(info) &info
47 #define StgBlockingQueue_blocking_queue(closure) \
48 (((StgBlockingQueue *)closure)->blocking_queue)
51 /* krc: there used to be an UPD_REAL_IND and an
52 UPD_PERM_IND, the latter of which was used for
53 ticky and cost-centre profiling.
54 for now, we just have UPD_REAL_IND. */
55 #define UPD_REAL_IND(updclosure, ind_info, heapptr, and_then) \
57 updateWithIndirection(ind_info, \
63 /* -----------------------------------------------------------------------------
64 Awaken any threads waiting on a blocking queue (BLACKHOLE_BQ).
65 -------------------------------------------------------------------------- */
67 /* -----------------------------------------------------------------------------
68 Updates: lower-level macros which update a closure with an
69 indirection to another closure.
71 There are several variants of this code.
74 -------------------------------------------------------------------------- */
77 * We call LDV_recordDead_FILL_SLOP_DYNAMIC(p1) regardless of the generation in
81 * After all, we do *NOT* need to call LDV_RECORD_CREATE() for both IND and
82 * IND_OLDGEN closures because they are inherently used. But, it corrupts
83 * the invariants that every closure keeps its creation time in the profiling
84 * field. So, we call LDV_RECORD_CREATE().
87 /* In the DEBUG case, we also zero out the slop of the old closure,
88 * so that the sanity checker can tell where the next closure is.
90 * Two important invariants: we should never try to update a closure
91 * to point to itself, and the closure being updated should not
92 * already have been updated (the mutable list will get messed up
95 * NB. We do *not* do this in THREADED_RTS mode, because when we have the
96 * possibility of multiple threads entering the same closure, zeroing
97 * the slop in one of the threads would have a disastrous effect on
98 * the other (seen in the wild!).
102 #define FILL_SLOP(p) \
106 inf = %GET_STD_INFO(p); \
107 if (%INFO_TYPE(inf) != HALF_W_(BLACKHOLE) \
108 && %INFO_TYPE(inf) != HALF_W_(CAF_BLACKHOLE)) { \
109 if (%INFO_TYPE(inf) == HALF_W_(THUNK_SELECTOR)) { \
110 sz = BYTES_TO_WDS(SIZEOF_StgSelector_NoThunkHdr); \
112 if (%INFO_TYPE(inf) == HALF_W_(AP_STACK)) { \
113 sz = StgAP_STACK_size(p) + BYTES_TO_WDS(SIZEOF_StgAP_STACK_NoThunkHdr); \
115 if (%INFO_TYPE(inf) == HALF_W_(AP)) { \
116 sz = TO_W_(StgAP_n_args(p)) + BYTES_TO_WDS(SIZEOF_StgAP_NoThunkHdr); \
118 sz = TO_W_(%INFO_PTRS(inf)) + TO_W_(%INFO_NPTRS(inf)); \
125 StgThunk_payload(p,i) = 0; \
131 #else /* !CMINUSMINUS */
134 FILL_SLOP(StgClosure *p)
136 StgInfoTable *inf = get_itbl(p);
143 // we already filled in the slop when we overwrote the thunk
144 // with BLACKHOLE, and also an evacuated BLACKHOLE is only the
147 sz = sizeofW(StgSelector) - sizeofW(StgThunkHeader);
150 sz = ((StgAP *)p)->n_args + sizeofW(StgAP) - sizeofW(StgThunkHeader);
153 sz = ((StgAP_STACK *)p)->size + sizeofW(StgAP_STACK) - sizeofW(StgThunkHeader);
156 sz = inf->layout.payload.ptrs + inf->layout.payload.nptrs;
159 for (i = 0; i < sz; i++) {
160 ((StgThunk *)p)->payload[i] = 0;
166 #endif /* CMINUSMINUS */
168 #if !defined(DEBUG) || defined(THREADED_RTS)
169 #define DEBUG_FILL_SLOP(p) /* do nothing */
171 #define DEBUG_FILL_SLOP(p) FILL_SLOP(p)
174 /* We have two versions of this macro (sadly), one for use in C-- code,
175 * and the other for C.
177 * The and_then argument is a performance hack so that we can paste in
178 * the continuation code directly. It helps shave a couple of
179 * instructions off the common case in the update code, which is
180 * worthwhile (the update code is often part of the inner loop).
181 * (except that gcc now appears to common up this code again and
182 * invert the optimisation. Grrrr --SDM).
185 #define generation(n) (W_[generations] + n*SIZEOF_generation)
186 #define updateWithIndirection(ind_info, p1, p2, and_then) \
189 DEBUG_FILL_SLOP(p1); \
190 LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1); \
191 StgInd_indirectee(p1) = p2; \
192 prim %write_barrier() []; \
194 if (bdescr_gen_no(bd) != 0 :: CInt) { \
195 recordMutableCap(p1, TO_W_(bdescr_gen_no(bd)), R1); \
196 SET_INFO(p1, stg_IND_OLDGEN_info); \
197 LDV_RECORD_CREATE(p1); \
198 TICK_UPD_OLD_IND(); \
201 SET_INFO(p1, ind_info); \
202 LDV_RECORD_CREATE(p1); \
203 TICK_UPD_NEW_IND(); \
207 #define updateWithIndirection(ind_info, p1, p2, and_then) \
211 ASSERT( (P_)p1 != (P_)p2 ); \
212 /* not necessarily true: ASSERT( !closure_IND(p1) ); */ \
213 /* occurs in RaiseAsync.c:raiseAsync() */ \
214 DEBUG_FILL_SLOP(p1); \
215 LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1); \
216 ((StgInd *)p1)->indirectee = p2; \
218 bd = Bdescr((P_)p1); \
219 if (bd->gen_no != 0) { \
220 recordMutableGenLock(p1, bd->gen_no); \
221 SET_INFO(p1, &stg_IND_OLDGEN_info); \
222 TICK_UPD_OLD_IND(); \
225 SET_INFO(p1, ind_info); \
226 LDV_RECORD_CREATE(p1); \
227 TICK_UPD_NEW_IND(); \
231 #endif /* CMINUSMINUS */
237 #endif /* UPDATES_H */