1 /* -----------------------------------------------------------------------------
2 * $Id: Updates.hc,v 1.20 1999/11/02 15:06:05 simonmar Exp $
4 * (c) The GHC Team, 1998-1999
6 * Code to perform updates.
8 * ---------------------------------------------------------------------------*/
13 #include "HeapStackCheck.h"
18 The update frame return address must be *polymorphic*, that means
19 we have to cope with both vectored and non-vectored returns. This
20 is done by putting the return vector right before the info table, and
21 having a standard direct return address after the info table (pointed
22 to by the return address itself, as usual).
24 Each entry in the vector table points to a specialised entry code fragment
25 that knows how to return after doing the update. It would be possible to
26 use a single generic piece of code that simply entered the return value
27 to return, but it's quicker this way. The direct return code of course
28 just does another direct return when it's finished.
30 Why is there necessarily an activation underneath us on the stack?
31 Because if we're returning, that means we've got a constructor in
32 our hands. If there were any arguments to be applied to it, that
33 would be a type error. We don't ever return a PAP to an update frame,
34 the update is handled manually by stg_update_PAP.
37 /* on entry to the update code
38 (1) R1 points to the closure being returned
39 (2) R2 contains the tag (if we returned directly, non-vectored)
40 (3) Sp points to the update frame
43 /* Why updatee is placed in a temporary variable here: this helps
44 gcc's aliasing by indicating that the location of the updatee
45 doesn't change across assignments. Saves one instruction in the
50 #define UPD_FRAME_ENTRY_TEMPLATE(label,ret) \
56 Su = (StgUpdateFrame *)((StgUpdateFrame *)Sp)->updatee; \
58 /* Tick - it must be a con, all the paps are handled \
59 * in stg_upd_PAP and PAP_entry below \
61 TICK_UPD_CON_IN_NEW(sizeW_fromITBL(get_itbl(Su))); \
63 /* update the updatee with an indirection to the return value */\
66 /* reset Su to the next update frame */ \
67 Su = ((StgUpdateFrame *)Sp)->link; \
69 /* remove the update frame from the stack */ \
70 Sp += sizeofW(StgUpdateFrame); \
77 #define UPD_FRAME_ENTRY_TEMPLATE(label,ret) \
81 StgClosure *updatee; \
84 updatee = ((StgUpdateFrame *)Sp)->updatee; \
86 /* Tick - it must be a con, all the paps are handled \
87 * in stg_upd_PAP and PAP_entry below \
89 TICK_UPD_CON_IN_NEW(sizeW_fromITBL(get_itbl(updatee))); \
91 /* update the updatee with an indirection to the return value */\
92 UPD_IND(updatee,R1.p); \
94 /* reset Su to the next update frame */ \
95 Su = ((StgUpdateFrame *)Sp)->link; \
97 /* remove the update frame from the stack */ \
98 Sp += sizeofW(StgUpdateFrame); \
105 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_entry,ENTRY_CODE(Sp[0]));
106 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_0_entry,RET_VEC(Sp[0],0));
107 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_1_entry,RET_VEC(Sp[0],1));
108 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_2_entry,RET_VEC(Sp[0],2));
109 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_3_entry,RET_VEC(Sp[0],3));
110 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_4_entry,RET_VEC(Sp[0],4));
111 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_5_entry,RET_VEC(Sp[0],5));
112 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_6_entry,RET_VEC(Sp[0],6));
113 UPD_FRAME_ENTRY_TEMPLATE(Upd_frame_7_entry,RET_VEC(Sp[0],7));
116 Make sure this table is big enough to handle the maximum vectored
121 #define UPD_FRAME_BITMAP 3
123 #define UPD_FRAME_BITMAP 1
126 /* this bitmap indicates that the first word of an update frame is a
127 * non-pointer - this is the update frame link. (for profiling,
128 * there's a cost-centre-stack in there too).
131 VEC_POLY_INFO_TABLE(Upd_frame,UPD_FRAME_BITMAP, NULL/*srt*/, 0/*srt_off*/, 0/*srt_len*/, UPDATE_FRAME,, EF_);
133 /* -----------------------------------------------------------------------------
134 Entry Code for a PAP.
136 The idea is to copy the chunk of stack from the PAP object and then
137 re-enter the function closure that failed it's args check in the
140 In fact, we do a little optimisation too, by performing the updates
141 for any update frames sitting on top of the stack. (ToDo: is this
142 really an optimisation? --SDM)
143 -------------------------------------------------------------------------- */
145 INFO_TABLE(PAP_info,PAP_entry,/*special layout*/0,0,PAP,,EF_,0,0);
155 pap = (StgPAP *) R1.p;
158 * remove any update frames on the top of the stack, by just
159 * performing the update here.
161 while ((W_)Su - (W_)Sp == 0) {
163 switch (get_itbl(Su)->type) {
166 /* We're sitting on top of an update frame, so let's do the business */
167 UPD_IND(Su->updatee, pap);
169 #if defined(PROFILING)
171 * Restore the Cost Centre too (if required); again see Sansom
172 * thesis p 183. Take the CC out of the update frame if a
176 CCCS = Su->header.prof.ccs;
177 #endif /* PROFILING */
180 Sp += sizeofW(StgUpdateFrame);
184 /* Just pop the seq frame and return to the activation record
185 * underneath us - R1 already contains the address of the PAP.
187 Su = ((StgSeqFrame *)Su)->link;
188 Sp += sizeofW(StgSeqFrame);
189 JMP_(ENTRY_CODE(*Sp));
192 /* can't happen, see stg_update_PAP */
193 barf("PAP_entry: CATCH_FRAME");
196 barf("PAP_entry: strange activation record");
204 * Check for stack overflow.
206 STK_CHK_NP(Words,1,);
211 /* Enter PAP cost centre -- lexical scoping only */
212 ENTER_CCS_PAP_CL(pap);
215 p = (P_)(pap->payload);
217 /* Reload the stack */
218 for (i=0; i<Words; i++) Sp[i] = (W_) *p++;
222 JMP_(GET_ENTRY(R1.cl));
226 /* -----------------------------------------------------------------------------
227 stg_update_PAP: Update the current closure with a partial application.
229 This function is called whenever an argument satisfaction check fails.
230 -------------------------------------------------------------------------- */
232 EXTFUN(stg_update_PAP)
236 CostCentreStack *CCS_pap;
239 StgClosure *Fun, *Updatee;
245 /* Save the pointer to the function closure that just failed the
246 * argument satisfaction check
250 #if defined(GRAN_COUNT)
255 /* Just copy the whole block of stack between the stack pointer
256 * and the update frame pointer.
258 Words = (P_)Su - (P_)Sp;
259 ASSERT((int)Words >= 0);
261 #if defined(PROFILING)
262 /* pretend we just entered the function closure */
270 * No arguments, only Node. Skip building the PAP and
271 * just plan to update with an indirection.
274 PapClosure = (StgPAP *)Fun;
279 PapSize = Words + sizeofW(StgPAP);
282 * First we need to do a heap check, which involves saving
283 * everything on the stack. We only have one live pointer:
284 * Fun, the function closure that was passed to us. If the
285 * heap check fails, we push the function closure on the stack
286 * and instruct the scheduler to try entering it again when
287 * the garbage collector has run.
289 * It's done this way because there's a possibility that the
290 * garbage collector might have messed around with the stack,
291 * such as removing the update frame.
293 if ((Hp += PapSize) > HpLim) {
296 JMP_(stg_gc_entertop);
299 TICK_ALLOC_UPD_PAP(1/*fun*/ + Words, 0);
301 CCS_ALLOC(CCS_pap, PapSize);
304 PapClosure = (StgPAP *)(Hp + 1 - PapSize); /* The new PapClosure */
306 SET_HDR(PapClosure,&PAP_info,CCS_pap);
307 PapClosure->n_args = Words;
308 PapClosure->fun = Fun;
310 /* Now fill in the closure fields */
313 for (i = Words-1; i >= 0; i--) {
319 * Finished constructing PAP closure; now update the updatee.
322 /* ToDo: we'd like to just jump to the code for PAP_entry here,
323 * which deals with a stack of update frames in one go. What to
324 * do about the special ticky and profiling stuff here?
327 switch (get_itbl(Su)->type) {
330 /* Set Sp to just above the SEQ frame (should be an activation rec.)*/
331 Sp = (P_)Su + sizeofW(StgSeqFrame);
334 Su = ((StgSeqFrame *)Su)->link;
336 /* return to the activation record, with the address of the PAP in R1 */
337 R1.p = (P_)PapClosure;
338 JMP_(ENTRY_CODE(*Sp));
341 /* Set Sp to just above the CATCH frame (should be an activation rec.)*/
342 Sp = (P_)Su + sizeofW(StgCatchFrame);
345 Su = ((StgCatchFrame *)Su)->link;
347 /* restart by entering the PAP */
348 R1.p = (P_)PapClosure;
349 JMP_(GET_ENTRY(R1.cl));
353 * Now we have a standard update frame, so we update the updatee with
354 * either the new PAP or Node.
357 Updatee = Su->updatee;
359 #if defined(PROFILING)
361 UPD_IND(Updatee,PapClosure);
362 TICK_UPD_PAP_IN_NEW(Words+1);
364 /* Lexical scoping requires a *permanent* indirection, and we
365 * also have to set the cost centre for the indirection.
367 UPD_PERM_IND(Updatee,PapClosure);
368 TICK_UPD_PAP_IN_PLACE();
369 Updatee->header.prof.ccs = CCS_pap;
372 UPD_IND(Updatee,PapClosure);
374 TICK_UPD_PAP_IN_NEW(Words+1);
376 TICK_UPD_PAP_IN_PLACE();
380 #if defined(PROFILING)
381 CCCS = Su->header.prof.ccs;
382 ENTER_CCS_PAP(CCS_pap);
383 #endif /* PROFILING */
389 * Squeeze out update frame from stack.
391 for (i = Words-1; i >= 0; i--) {
392 Sp[i+(sizeofW(StgUpdateFrame))] = Sp[i];
394 Sp += sizeofW(StgUpdateFrame);
398 barf("stg_update_PAP: strange activation record");
402 * All done! Restart by re-entering Node
403 * Don't count this entry for ticky-ticky profiling.
405 JMP_(GET_ENTRY(R1.cl));
410 /* -----------------------------------------------------------------------------
411 Entry Code for an AP_UPD.
413 The idea is to copy the chunk of stack from the AP object and then
414 enter the function closure.
416 (This code is a simplified copy of the PAP code - with all the
417 update frame code stripped out.)
418 -------------------------------------------------------------------------- */
421 INFO_TABLE(AP_UPD_info,AP_UPD_entry,/*special layout*/0,0,AP_UPD,,EF_,0,0);
431 ap = (StgAP_UPD *) R1.p;
436 * Check for stack overflow.
438 STK_CHK(Words+sizeofW(StgUpdateFrame),AP_UPD_entry,R2.p,1,);
440 PUSH_UPD_FRAME(R1.p, 0);
441 Sp -= sizeofW(StgUpdateFrame) + Words;
445 /* Enter PAP cost centre -- lexical scoping only */
446 ENTER_CCS_PAP_CL(ap); /* ToDo: ENTER_CC_AP_UPD_CL */
449 p = (P_)(ap->payload);
451 /* Reload the stack */
452 for (i=0; i<Words; i++) Sp[i] = (W_) *p++;
456 JMP_(GET_ENTRY(R1.cl));
461 /*-----------------------------------------------------------------------------
464 We don't have a primitive seq# operator: it is just a 'case'
465 expression whose scrutinee has either a polymorphic or function type
466 (constructor types can be handled by normal 'case' expressions).
468 To handle a polymorphic/function typed seq, we push a SEQ_FRAME on
469 the stack. This is a polymorphic activation record that just pops
470 itself and returns when entered. The purpose of the SEQ_FRAME is to
471 act as a barrier in case the scrutinee is a partial application - in
472 this way it is just like an update frame, except that it doesn't
474 -------------------------------------------------------------------------- */
476 #define SEQ_FRAME_ENTRY_TEMPLATE(label,ret) \
480 Su = ((StgSeqFrame *)Sp)->link; \
481 Sp += sizeofW(StgSeqFrame); \
486 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_entry, ENTRY_CODE(Sp[0]));
487 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_0_entry,ENTRY_CODE(Sp[0]));
488 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_1_entry,ENTRY_CODE(Sp[0]));
489 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_2_entry,ENTRY_CODE(Sp[0]));
490 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_3_entry,ENTRY_CODE(Sp[0]));
491 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_4_entry,ENTRY_CODE(Sp[0]));
492 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_5_entry,ENTRY_CODE(Sp[0]));
493 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_6_entry,ENTRY_CODE(Sp[0]));
494 SEQ_FRAME_ENTRY_TEMPLATE(seq_frame_7_entry,ENTRY_CODE(Sp[0]));
496 VEC_POLY_INFO_TABLE(seq_frame, UPD_FRAME_BITMAP, NULL/*srt*/, 0/*srt_off*/, 0/*srt_len*/, SEQ_FRAME,, EF_);
498 /* -----------------------------------------------------------------------------
501 * This closure takes one argument, which it evaluates and returns the
502 * result with a direct return (never a vectored return!) in R1. It
503 * does this by pushing a SEQ_FRAME on the stack and
504 * entering its argument.
506 * It is used in deleteThread when reverting blackholes.
507 * -------------------------------------------------------------------------- */
509 INFO_TABLE(seq_info,seq_entry,1,0,FUN,,EF_,0,0);
513 STK_CHK_GEN(sizeofW(StgSeqFrame), NO_PTRS, seq_entry, );
514 Sp -= sizeofW(StgSeqFrame);
516 R1.cl = R1.cl->payload[0];
517 JMP_(ENTRY_CODE(*R1.p));
522 /* -----------------------------------------------------------------------------
524 -------------------------------------------------------------------------- */
529 #define CATCH_FRAME_ENTRY_TEMPLATE(label,ret) \
534 Su = ((StgCatchFrame *)Sp)->link; \
535 Sp += sizeofW(StgCatchFrame); \
540 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_entry,ENTRY_CODE(Sp[0]));
541 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_0_entry,RET_VEC(Sp[0],0));
542 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_1_entry,RET_VEC(Sp[0],1));
543 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_2_entry,RET_VEC(Sp[0],2));
544 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_3_entry,RET_VEC(Sp[0],3));
545 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_4_entry,RET_VEC(Sp[0],4));
546 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_5_entry,RET_VEC(Sp[0],5));
547 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_6_entry,RET_VEC(Sp[0],6));
548 CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_7_entry,RET_VEC(Sp[0],7));
551 #define CATCH_FRAME_BITMAP 3
553 #define CATCH_FRAME_BITMAP 1
556 /* Catch frames are very similar to update frames, but when entering
557 * one we just pop the frame off the stack and perform the correct
558 * kind of return to the activation record underneath us on the stack.
561 VEC_POLY_INFO_TABLE(catch_frame, CATCH_FRAME_BITMAP, NULL/*srt*/, 0/*srt_off*/, 0/*srt_len*/, CATCH_FRAME,, EF_);
563 /* -----------------------------------------------------------------------------
564 * The catch infotable
566 * This should be exactly the same as would be generated by this STG code
568 * catch = {x,h} \n {} -> catch#{x,h}
570 * It is used in deleteThread when reverting blackholes.
571 * -------------------------------------------------------------------------- */
573 INFO_TABLE(catch_info,catch_entry,2,0,FUN,,EF_,0,0);
577 R2.cl = payloadCPtr(R1.cl,1); /* h */
578 R1.cl = payloadCPtr(R1.cl,0); /* x */
588 /* args: R1 = m, R2 = k */
589 STK_CHK_GEN(sizeofW(StgCatchFrame), R1_PTR | R2_PTR, catchzh_fast, );
590 Sp -= sizeofW(StgCatchFrame);
591 fp = (StgCatchFrame *)Sp;
592 SET_HDR(fp,(StgInfoTable *)&catch_frame_info,CCCS);
593 fp -> handler = R2.cl;
595 Su = (StgUpdateFrame *)fp;
596 TICK_CATCHF_PUSHED();
598 JMP_(ENTRY_CODE(*R1.p));
603 /* -----------------------------------------------------------------------------
604 * The raise infotable
606 * This should be exactly the same as would be generated by this STG code
608 * raise = {err} \n {} -> raise#{err}
610 * It is used in raisezh_fast to update thunks on the update list
611 * -------------------------------------------------------------------------- */
613 INFO_TABLE(raise_info,raise_entry,1,0,FUN,,EF_,0,0);
617 R1.cl = R1.cl->payload[0];
626 StgClosure *raise_closure;
628 /* args : R1 = error */
632 /* This closure represents the expression 'raise# E' where E
633 * is the exception raise. It is used to overwrite all the
634 * thunks which are currently under evaluataion.
636 raise_closure = (StgClosure *)RET_STGCALL1(P_,allocate,
637 sizeofW(StgClosure)+1);
638 raise_closure->header.info = &raise_info;
639 raise_closure->payload[0] = R1.cl;
643 switch (get_itbl(p)->type) {
646 UPD_IND(p->updatee,raise_closure);
651 p = ((StgSeqFrame *)p)->link;
659 barf("raisezh_fast: STOP_FRAME");
662 barf("raisezh_fast: weird activation record");
669 /* Ok, p points to the enclosing CATCH_FRAME. Pop everything down to
670 * and including this frame, update Su, push R1, and enter the handler.
672 Su = ((StgCatchFrame *)p)->link;
673 handler = ((StgCatchFrame *)p)->handler;
675 Sp = (P_)p + sizeofW(StgCatchFrame) - 1;
680 JMP_(ENTRY_CODE(handler->header.info));