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GHCi debugger: new flag -fbreak-on-exception
[ghc.git] / rts / Interpreter.c
1 /* -----------------------------------------------------------------------------
2 * Bytecode interpreter
3 *
4 * Copyright (c) The GHC Team, 1994-2002.
5 * ---------------------------------------------------------------------------*/
6
7 #include "PosixSource.h"
8 #include "Rts.h"
9 #include "RtsAPI.h"
10 #include "RtsUtils.h"
11 #include "Closures.h"
12 #include "TSO.h"
13 #include "Schedule.h"
14 #include "RtsFlags.h"
15 #include "LdvProfile.h"
16 #include "Updates.h"
17 #include "Sanity.h"
18 #include "Liveness.h"
19 #include "Prelude.h"
20
21 #include "Bytecodes.h"
22 #include "Printer.h"
23 #include "Disassembler.h"
24 #include "Interpreter.h"
25
26 #include <string.h> /* for memcpy */
27 #ifdef HAVE_ERRNO_H
28 #include <errno.h>
29 #endif
30
31
32 /* --------------------------------------------------------------------------
33 * The bytecode interpreter
34 * ------------------------------------------------------------------------*/
35
36 /* Gather stats about entry, opcode, opcode-pair frequencies. For
37 tuning the interpreter. */
38
39 /* #define INTERP_STATS */
40
41
42 /* Sp points to the lowest live word on the stack. */
43
44 #define BCO_NEXT instrs[bciPtr++]
45 #define BCO_NEXT_32 (bciPtr += 2, (((StgWord) instrs[bciPtr-2]) << 16) + ((StgWord) instrs[bciPtr-1]))
46 #define BCO_NEXT_64 (bciPtr += 4, (((StgWord) instrs[bciPtr-4]) << 48) + (((StgWord) instrs[bciPtr-3]) << 32) + (((StgWord) instrs[bciPtr-2]) << 16) + ((StgWord) instrs[bciPtr-1]))
47 #if WORD_SIZE_IN_BITS == 32
48 #define BCO_NEXT_WORD BCO_NEXT_32
49 #elif WORD_SIZE_IN_BITS == 64
50 #define BCO_NEXT_WORD BCO_NEXT_64
51 #else
52 #error Cannot cope with WORD_SIZE_IN_BITS being nether 32 nor 64
53 #endif
54 #define BCO_GET_LARGE_ARG ((bci & bci_FLAG_LARGE_ARGS) ? BCO_NEXT_WORD : BCO_NEXT)
55
56 #define BCO_PTR(n) (W_)ptrs[n]
57 #define BCO_LIT(n) literals[n]
58
59 #define LOAD_STACK_POINTERS \
60 Sp = cap->r.rCurrentTSO->sp; \
61 /* We don't change this ... */ \
62 SpLim = cap->r.rCurrentTSO->stack + RESERVED_STACK_WORDS;
63
64 #define SAVE_STACK_POINTERS \
65 cap->r.rCurrentTSO->sp = Sp
66
67 #define RETURN_TO_SCHEDULER(todo,retcode) \
68 SAVE_STACK_POINTERS; \
69 cap->r.rCurrentTSO->what_next = (todo); \
70 threadPaused(cap,cap->r.rCurrentTSO); \
71 cap->r.rRet = (retcode); \
72 return cap;
73
74 #define RETURN_TO_SCHEDULER_NO_PAUSE(todo,retcode) \
75 SAVE_STACK_POINTERS; \
76 cap->r.rCurrentTSO->what_next = (todo); \
77 cap->r.rRet = (retcode); \
78 return cap;
79
80
81 STATIC_INLINE StgPtr
82 allocate_NONUPD (int n_words)
83 {
84 return allocate(stg_max(sizeofW(StgHeader)+MIN_PAYLOAD_SIZE, n_words));
85 }
86
87 int rts_stop_next_breakpoint = 0;
88 int rts_stop_on_exception = 0;
89
90 #ifdef INTERP_STATS
91
92 /* Hacky stats, for tuning the interpreter ... */
93 int it_unknown_entries[N_CLOSURE_TYPES];
94 int it_total_unknown_entries;
95 int it_total_entries;
96
97 int it_retto_BCO;
98 int it_retto_UPDATE;
99 int it_retto_other;
100
101 int it_slides;
102 int it_insns;
103 int it_BCO_entries;
104
105 int it_ofreq[27];
106 int it_oofreq[27][27];
107 int it_lastopc;
108
109
110 #define INTERP_TICK(n) (n)++
111
112 void interp_startup ( void )
113 {
114 int i, j;
115 it_retto_BCO = it_retto_UPDATE = it_retto_other = 0;
116 it_total_entries = it_total_unknown_entries = 0;
117 for (i = 0; i < N_CLOSURE_TYPES; i++)
118 it_unknown_entries[i] = 0;
119 it_slides = it_insns = it_BCO_entries = 0;
120 for (i = 0; i < 27; i++) it_ofreq[i] = 0;
121 for (i = 0; i < 27; i++)
122 for (j = 0; j < 27; j++)
123 it_oofreq[i][j] = 0;
124 it_lastopc = 0;
125 }
126
127 void interp_shutdown ( void )
128 {
129 int i, j, k, o_max, i_max, j_max;
130 debugBelch("%d constrs entered -> (%d BCO, %d UPD, %d ??? )\n",
131 it_retto_BCO + it_retto_UPDATE + it_retto_other,
132 it_retto_BCO, it_retto_UPDATE, it_retto_other );
133 debugBelch("%d total entries, %d unknown entries \n",
134 it_total_entries, it_total_unknown_entries);
135 for (i = 0; i < N_CLOSURE_TYPES; i++) {
136 if (it_unknown_entries[i] == 0) continue;
137 debugBelch(" type %2d: unknown entries (%4.1f%%) == %d\n",
138 i, 100.0 * ((double)it_unknown_entries[i]) /
139 ((double)it_total_unknown_entries),
140 it_unknown_entries[i]);
141 }
142 debugBelch("%d insns, %d slides, %d BCO_entries\n",
143 it_insns, it_slides, it_BCO_entries);
144 for (i = 0; i < 27; i++)
145 debugBelch("opcode %2d got %d\n", i, it_ofreq[i] );
146
147 for (k = 1; k < 20; k++) {
148 o_max = 0;
149 i_max = j_max = 0;
150 for (i = 0; i < 27; i++) {
151 for (j = 0; j < 27; j++) {
152 if (it_oofreq[i][j] > o_max) {
153 o_max = it_oofreq[i][j];
154 i_max = i; j_max = j;
155 }
156 }
157 }
158
159 debugBelch("%d: count (%4.1f%%) %6d is %d then %d\n",
160 k, ((double)o_max) * 100.0 / ((double)it_insns), o_max,
161 i_max, j_max );
162 it_oofreq[i_max][j_max] = 0;
163
164 }
165 }
166
167 #else // !INTERP_STATS
168
169 #define INTERP_TICK(n) /* nothing */
170
171 #endif
172
173 static StgWord app_ptrs_itbl[] = {
174 (W_)&stg_ap_p_info,
175 (W_)&stg_ap_pp_info,
176 (W_)&stg_ap_ppp_info,
177 (W_)&stg_ap_pppp_info,
178 (W_)&stg_ap_ppppp_info,
179 (W_)&stg_ap_pppppp_info,
180 };
181
182 HsStablePtr rts_breakpoint_io_action; // points to the IO action which is executed on a breakpoint
183 // it is set in main/GHC.hs:runStmt
184
185 Capability *
186 interpretBCO (Capability* cap)
187 {
188 // Use of register here is primarily to make it clear to compilers
189 // that these entities are non-aliasable.
190 register StgPtr Sp; // local state -- stack pointer
191 register StgPtr SpLim; // local state -- stack lim pointer
192 register StgClosure* obj;
193 nat n, m;
194
195 LOAD_STACK_POINTERS;
196
197 // ------------------------------------------------------------------------
198 // Case 1:
199 //
200 // We have a closure to evaluate. Stack looks like:
201 //
202 // | XXXX_info |
203 // +---------------+
204 // Sp | -------------------> closure
205 // +---------------+
206 //
207 if (Sp[0] == (W_)&stg_enter_info) {
208 Sp++;
209 goto eval;
210 }
211
212 // ------------------------------------------------------------------------
213 // Case 2:
214 //
215 // We have a BCO application to perform. Stack looks like:
216 //
217 // | .... |
218 // +---------------+
219 // | arg1 |
220 // +---------------+
221 // | BCO |
222 // +---------------+
223 // Sp | RET_BCO |
224 // +---------------+
225 //
226 else if (Sp[0] == (W_)&stg_apply_interp_info) {
227 obj = (StgClosure *)Sp[1];
228 Sp += 2;
229 goto run_BCO_fun;
230 }
231
232 // ------------------------------------------------------------------------
233 // Case 3:
234 //
235 // We have an unboxed value to return. See comment before
236 // do_return_unboxed, below.
237 //
238 else {
239 goto do_return_unboxed;
240 }
241
242 // Evaluate the object on top of the stack.
243 eval:
244 obj = (StgClosure*)Sp[0]; Sp++;
245
246 eval_obj:
247 INTERP_TICK(it_total_evals);
248
249 IF_DEBUG(interpreter,
250 debugBelch(
251 "\n---------------------------------------------------------------\n");
252 debugBelch("Evaluating: "); printObj(obj);
253 debugBelch("Sp = %p\n", Sp);
254 debugBelch("\n" );
255
256 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
257 debugBelch("\n\n");
258 );
259
260 IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size));
261
262 switch ( get_itbl(obj)->type ) {
263
264 case IND:
265 case IND_OLDGEN:
266 case IND_PERM:
267 case IND_OLDGEN_PERM:
268 case IND_STATIC:
269 {
270 obj = ((StgInd*)obj)->indirectee;
271 goto eval_obj;
272 }
273
274 case CONSTR:
275 case CONSTR_1_0:
276 case CONSTR_0_1:
277 case CONSTR_2_0:
278 case CONSTR_1_1:
279 case CONSTR_0_2:
280 case CONSTR_STATIC:
281 case CONSTR_NOCAF_STATIC:
282 case FUN:
283 case FUN_1_0:
284 case FUN_0_1:
285 case FUN_2_0:
286 case FUN_1_1:
287 case FUN_0_2:
288 case FUN_STATIC:
289 case PAP:
290 // already in WHNF
291 break;
292
293 case BCO:
294 {
295 ASSERT(((StgBCO *)obj)->arity > 0);
296 break;
297 }
298
299 case AP: /* Copied from stg_AP_entry. */
300 {
301 nat i, words;
302 StgAP *ap;
303
304 ap = (StgAP*)obj;
305 words = ap->n_args;
306
307 // Stack check
308 if (Sp - (words+sizeofW(StgUpdateFrame)) < SpLim) {
309 Sp -= 2;
310 Sp[1] = (W_)obj;
311 Sp[0] = (W_)&stg_enter_info;
312 RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow);
313 }
314
315 /* Ok; we're safe. Party on. Push an update frame. */
316 Sp -= sizeofW(StgUpdateFrame);
317 {
318 StgUpdateFrame *__frame;
319 __frame = (StgUpdateFrame *)Sp;
320 SET_INFO(__frame, (StgInfoTable *)&stg_upd_frame_info);
321 __frame->updatee = (StgClosure *)(ap);
322 }
323
324 /* Reload the stack */
325 Sp -= words;
326 for (i=0; i < words; i++) {
327 Sp[i] = (W_)ap->payload[i];
328 }
329
330 obj = (StgClosure*)ap->fun;
331 ASSERT(get_itbl(obj)->type == BCO);
332 goto run_BCO_fun;
333 }
334
335 default:
336 #ifdef INTERP_STATS
337 {
338 int j;
339
340 j = get_itbl(obj)->type;
341 ASSERT(j >= 0 && j < N_CLOSURE_TYPES);
342 it_unknown_entries[j]++;
343 it_total_unknown_entries++;
344 }
345 #endif
346 {
347 // Can't handle this object; yield to scheduler
348 IF_DEBUG(interpreter,
349 debugBelch("evaluating unknown closure -- yielding to sched\n");
350 printObj(obj);
351 );
352 Sp -= 2;
353 Sp[1] = (W_)obj;
354 Sp[0] = (W_)&stg_enter_info;
355 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
356 }
357 }
358
359 // ------------------------------------------------------------------------
360 // We now have an evaluated object (obj). The next thing to
361 // do is return it to the stack frame on top of the stack.
362 do_return:
363 ASSERT(closure_HNF(obj));
364
365 IF_DEBUG(interpreter,
366 debugBelch(
367 "\n---------------------------------------------------------------\n");
368 debugBelch("Returning: "); printObj(obj);
369 debugBelch("Sp = %p\n", Sp);
370 debugBelch("\n" );
371 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
372 debugBelch("\n\n");
373 );
374
375 IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size));
376
377 switch (get_itbl((StgClosure *)Sp)->type) {
378
379 case RET_SMALL: {
380 const StgInfoTable *info;
381
382 // NOTE: not using get_itbl().
383 info = ((StgClosure *)Sp)->header.info;
384 if (info == (StgInfoTable *)&stg_ap_v_info) {
385 n = 1; m = 0; goto do_apply;
386 }
387 if (info == (StgInfoTable *)&stg_ap_f_info) {
388 n = 1; m = 1; goto do_apply;
389 }
390 if (info == (StgInfoTable *)&stg_ap_d_info) {
391 n = 1; m = sizeofW(StgDouble); goto do_apply;
392 }
393 if (info == (StgInfoTable *)&stg_ap_l_info) {
394 n = 1; m = sizeofW(StgInt64); goto do_apply;
395 }
396 if (info == (StgInfoTable *)&stg_ap_n_info) {
397 n = 1; m = 1; goto do_apply;
398 }
399 if (info == (StgInfoTable *)&stg_ap_p_info) {
400 n = 1; m = 1; goto do_apply;
401 }
402 if (info == (StgInfoTable *)&stg_ap_pp_info) {
403 n = 2; m = 2; goto do_apply;
404 }
405 if (info == (StgInfoTable *)&stg_ap_ppp_info) {
406 n = 3; m = 3; goto do_apply;
407 }
408 if (info == (StgInfoTable *)&stg_ap_pppp_info) {
409 n = 4; m = 4; goto do_apply;
410 }
411 if (info == (StgInfoTable *)&stg_ap_ppppp_info) {
412 n = 5; m = 5; goto do_apply;
413 }
414 if (info == (StgInfoTable *)&stg_ap_pppppp_info) {
415 n = 6; m = 6; goto do_apply;
416 }
417 goto do_return_unrecognised;
418 }
419
420 case UPDATE_FRAME:
421 // Returning to an update frame: do the update, pop the update
422 // frame, and continue with the next stack frame.
423 INTERP_TICK(it_retto_UPDATE);
424 UPD_IND(((StgUpdateFrame *)Sp)->updatee, obj);
425 Sp += sizeofW(StgUpdateFrame);
426 goto do_return;
427
428 case RET_BCO:
429 // Returning to an interpreted continuation: put the object on
430 // the stack, and start executing the BCO.
431 INTERP_TICK(it_retto_BCO);
432 Sp--;
433 Sp[0] = (W_)obj;
434 obj = (StgClosure*)Sp[2];
435 ASSERT(get_itbl(obj)->type == BCO);
436 goto run_BCO_return;
437
438 default:
439 do_return_unrecognised:
440 {
441 // Can't handle this return address; yield to scheduler
442 INTERP_TICK(it_retto_other);
443 IF_DEBUG(interpreter,
444 debugBelch("returning to unknown frame -- yielding to sched\n");
445 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
446 );
447 Sp -= 2;
448 Sp[1] = (W_)obj;
449 Sp[0] = (W_)&stg_enter_info;
450 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
451 }
452 }
453
454 // -------------------------------------------------------------------------
455 // Returning an unboxed value. The stack looks like this:
456 //
457 // | .... |
458 // +---------------+
459 // | fv2 |
460 // +---------------+
461 // | fv1 |
462 // +---------------+
463 // | BCO |
464 // +---------------+
465 // | stg_ctoi_ret_ |
466 // +---------------+
467 // | retval |
468 // +---------------+
469 // | XXXX_info |
470 // +---------------+
471 //
472 // where XXXX_info is one of the stg_gc_unbx_r1_info family.
473 //
474 // We're only interested in the case when the real return address
475 // is a BCO; otherwise we'll return to the scheduler.
476
477 do_return_unboxed:
478 {
479 int offset;
480
481 ASSERT( Sp[0] == (W_)&stg_gc_unbx_r1_info
482 || Sp[0] == (W_)&stg_gc_unpt_r1_info
483 || Sp[0] == (W_)&stg_gc_f1_info
484 || Sp[0] == (W_)&stg_gc_d1_info
485 || Sp[0] == (W_)&stg_gc_l1_info
486 || Sp[0] == (W_)&stg_gc_void_info // VoidRep
487 );
488
489 // get the offset of the stg_ctoi_ret_XXX itbl
490 offset = stack_frame_sizeW((StgClosure *)Sp);
491
492 switch (get_itbl((StgClosure *)Sp+offset)->type) {
493
494 case RET_BCO:
495 // Returning to an interpreted continuation: put the object on
496 // the stack, and start executing the BCO.
497 INTERP_TICK(it_retto_BCO);
498 obj = (StgClosure*)Sp[offset+1];
499 ASSERT(get_itbl(obj)->type == BCO);
500 goto run_BCO_return_unboxed;
501
502 default:
503 {
504 // Can't handle this return address; yield to scheduler
505 INTERP_TICK(it_retto_other);
506 IF_DEBUG(interpreter,
507 debugBelch("returning to unknown frame -- yielding to sched\n");
508 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
509 );
510 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
511 }
512 }
513 }
514 // not reached.
515
516
517 // -------------------------------------------------------------------------
518 // Application...
519
520 do_apply:
521 // we have a function to apply (obj), and n arguments taking up m
522 // words on the stack. The info table (stg_ap_pp_info or whatever)
523 // is on top of the arguments on the stack.
524 {
525 switch (get_itbl(obj)->type) {
526
527 case PAP: {
528 StgPAP *pap;
529 nat i, arity;
530
531 pap = (StgPAP *)obj;
532
533 // we only cope with PAPs whose function is a BCO
534 if (get_itbl(pap->fun)->type != BCO) {
535 goto defer_apply_to_sched;
536 }
537
538 Sp++;
539 arity = pap->arity;
540 ASSERT(arity > 0);
541 if (arity < n) {
542 // n must be greater than 1, and the only kinds of
543 // application we support with more than one argument
544 // are all pointers...
545 //
546 // Shuffle the args for this function down, and put
547 // the appropriate info table in the gap.
548 for (i = 0; i < arity; i++) {
549 Sp[(int)i-1] = Sp[i];
550 // ^^^^^ careful, i-1 might be negative, but i in unsigned
551 }
552 Sp[arity-1] = app_ptrs_itbl[n-arity-1];
553 Sp--;
554 // unpack the PAP's arguments onto the stack
555 Sp -= pap->n_args;
556 for (i = 0; i < pap->n_args; i++) {
557 Sp[i] = (W_)pap->payload[i];
558 }
559 obj = pap->fun;
560 goto run_BCO_fun;
561 }
562 else if (arity == n) {
563 Sp -= pap->n_args;
564 for (i = 0; i < pap->n_args; i++) {
565 Sp[i] = (W_)pap->payload[i];
566 }
567 obj = pap->fun;
568 goto run_BCO_fun;
569 }
570 else /* arity > n */ {
571 // build a new PAP and return it.
572 StgPAP *new_pap;
573 new_pap = (StgPAP *)allocate(PAP_sizeW(pap->n_args + m));
574 SET_HDR(new_pap,&stg_PAP_info,CCCS);
575 new_pap->arity = pap->arity - n;
576 new_pap->n_args = pap->n_args + m;
577 new_pap->fun = pap->fun;
578 for (i = 0; i < pap->n_args; i++) {
579 new_pap->payload[i] = pap->payload[i];
580 }
581 for (i = 0; i < m; i++) {
582 new_pap->payload[pap->n_args + i] = (StgClosure *)Sp[i];
583 }
584 obj = (StgClosure *)new_pap;
585 Sp += m;
586 goto do_return;
587 }
588 }
589
590 case BCO: {
591 nat arity, i;
592
593 Sp++;
594 arity = ((StgBCO *)obj)->arity;
595 ASSERT(arity > 0);
596 if (arity < n) {
597 // n must be greater than 1, and the only kinds of
598 // application we support with more than one argument
599 // are all pointers...
600 //
601 // Shuffle the args for this function down, and put
602 // the appropriate info table in the gap.
603 for (i = 0; i < arity; i++) {
604 Sp[(int)i-1] = Sp[i];
605 // ^^^^^ careful, i-1 might be negative, but i in unsigned
606 }
607 Sp[arity-1] = app_ptrs_itbl[n-arity-1];
608 Sp--;
609 goto run_BCO_fun;
610 }
611 else if (arity == n) {
612 goto run_BCO_fun;
613 }
614 else /* arity > n */ {
615 // build a PAP and return it.
616 StgPAP *pap;
617 nat i;
618 pap = (StgPAP *)allocate(PAP_sizeW(m));
619 SET_HDR(pap, &stg_PAP_info,CCCS);
620 pap->arity = arity - n;
621 pap->fun = obj;
622 pap->n_args = m;
623 for (i = 0; i < m; i++) {
624 pap->payload[i] = (StgClosure *)Sp[i];
625 }
626 obj = (StgClosure *)pap;
627 Sp += m;
628 goto do_return;
629 }
630 }
631
632 // No point in us applying machine-code functions
633 default:
634 defer_apply_to_sched:
635 Sp -= 2;
636 Sp[1] = (W_)obj;
637 Sp[0] = (W_)&stg_enter_info;
638 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
639 }
640
641 // ------------------------------------------------------------------------
642 // Ok, we now have a bco (obj), and its arguments are all on the
643 // stack. We can start executing the byte codes.
644 //
645 // The stack is in one of two states. First, if this BCO is a
646 // function:
647 //
648 // | .... |
649 // +---------------+
650 // | arg2 |
651 // +---------------+
652 // | arg1 |
653 // +---------------+
654 //
655 // Second, if this BCO is a continuation:
656 //
657 // | .... |
658 // +---------------+
659 // | fv2 |
660 // +---------------+
661 // | fv1 |
662 // +---------------+
663 // | BCO |
664 // +---------------+
665 // | stg_ctoi_ret_ |
666 // +---------------+
667 // | retval |
668 // +---------------+
669 //
670 // where retval is the value being returned to this continuation.
671 // In the event of a stack check, heap check, or context switch,
672 // we need to leave the stack in a sane state so the garbage
673 // collector can find all the pointers.
674 //
675 // (1) BCO is a function: the BCO's bitmap describes the
676 // pointerhood of the arguments.
677 //
678 // (2) BCO is a continuation: BCO's bitmap describes the
679 // pointerhood of the free variables.
680 //
681 // Sadly we have three different kinds of stack/heap/cswitch check
682 // to do:
683
684
685 run_BCO_return:
686 // Heap check
687 if (doYouWantToGC()) {
688 Sp--; Sp[0] = (W_)&stg_enter_info;
689 RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow);
690 }
691 // Stack checks aren't necessary at return points, the stack use
692 // is aggregated into the enclosing function entry point.
693
694 goto run_BCO;
695
696 run_BCO_return_unboxed:
697 // Heap check
698 if (doYouWantToGC()) {
699 RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow);
700 }
701 // Stack checks aren't necessary at return points, the stack use
702 // is aggregated into the enclosing function entry point.
703
704 goto run_BCO;
705
706 run_BCO_fun:
707 IF_DEBUG(sanity,
708 Sp -= 2;
709 Sp[1] = (W_)obj;
710 Sp[0] = (W_)&stg_apply_interp_info;
711 checkStackChunk(Sp,SpLim);
712 Sp += 2;
713 );
714
715 // Heap check
716 if (doYouWantToGC()) {
717 Sp -= 2;
718 Sp[1] = (W_)obj;
719 Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really
720 RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow);
721 }
722
723 // Stack check
724 if (Sp - INTERP_STACK_CHECK_THRESH < SpLim) {
725 Sp -= 2;
726 Sp[1] = (W_)obj;
727 Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really
728 RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow);
729 }
730
731 goto run_BCO;
732
733 // Now, actually interpret the BCO... (no returning to the
734 // scheduler again until the stack is in an orderly state).
735 run_BCO:
736 INTERP_TICK(it_BCO_entries);
737 {
738 register int bciPtr = 1; /* instruction pointer */
739 register StgWord16 bci;
740 register StgBCO* bco = (StgBCO*)obj;
741 register StgWord16* instrs = (StgWord16*)(bco->instrs->payload);
742 register StgWord* literals = (StgWord*)(&bco->literals->payload[0]);
743 register StgPtr* ptrs = (StgPtr*)(&bco->ptrs->payload[0]);
744
745 #ifdef INTERP_STATS
746 it_lastopc = 0; /* no opcode */
747 #endif
748
749 nextInsn:
750 ASSERT(bciPtr <= instrs[0]);
751 IF_DEBUG(interpreter,
752 //if (do_print_stack) {
753 //debugBelch("\n-- BEGIN stack\n");
754 //printStack(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size,iSu);
755 //debugBelch("-- END stack\n\n");
756 //}
757 debugBelch("Sp = %p pc = %d ", Sp, bciPtr);
758 disInstr(bco,bciPtr);
759 if (0) { int i;
760 debugBelch("\n");
761 for (i = 8; i >= 0; i--) {
762 debugBelch("%d %p\n", i, (StgPtr)(*(Sp+i)));
763 }
764 debugBelch("\n");
765 }
766 //if (do_print_stack) checkStack(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size,iSu);
767 );
768
769
770 INTERP_TICK(it_insns);
771
772 #ifdef INTERP_STATS
773 ASSERT( (int)instrs[bciPtr] >= 0 && (int)instrs[bciPtr] < 27 );
774 it_ofreq[ (int)instrs[bciPtr] ] ++;
775 it_oofreq[ it_lastopc ][ (int)instrs[bciPtr] ] ++;
776 it_lastopc = (int)instrs[bciPtr];
777 #endif
778
779 bci = BCO_NEXT;
780 /* We use the high 8 bits for flags, only the highest of which is
781 * currently allocated */
782 ASSERT((bci & 0xFF00) == (bci & 0x8000));
783
784 switch (bci & 0xFF) {
785
786 /* check for a breakpoint on the beginning of a let binding */
787 case bci_BRK_FUN:
788 {
789 int arg1_brk_array, arg2_array_index, arg3_freeVars;
790 StgArrWords *breakPoints;
791 int returning_from_break; // are we resuming execution from a breakpoint?
792 // if yes, then don't break this time around
793 StgClosure *ioAction; // the io action to run at a breakpoint
794
795 StgAP_STACK *new_aps; // a closure to save the top stack frame on the heap
796 int i;
797 int size_words;
798
799 arg1_brk_array = BCO_NEXT; // 1st arg of break instruction
800 arg2_array_index = BCO_NEXT; // 2nd arg of break instruction
801 arg3_freeVars = BCO_NEXT; // 3rd arg of break instruction
802
803 // check if we are returning from a breakpoint - this info
804 // is stored in the flags field of the current TSO
805 returning_from_break = cap->r.rCurrentTSO->flags & TSO_STOPPED_ON_BREAKPOINT;
806
807 // if we are returning from a break then skip this section
808 // and continue executing
809 if (!returning_from_break)
810 {
811 breakPoints = (StgArrWords *) BCO_PTR(arg1_brk_array);
812
813 // stop the current thread if either the
814 // "rts_stop_next_breakpoint" flag is true OR if the
815 // breakpoint flag for this particular expression is
816 // true
817 if (rts_stop_next_breakpoint == rtsTrue ||
818 breakPoints->payload[arg2_array_index] == rtsTrue)
819 {
820 // make sure we don't automatically stop at the
821 // next breakpoint
822 rts_stop_next_breakpoint = rtsFalse;
823
824 // allocate memory for a new AP_STACK, enough to
825 // store the top stack frame plus an
826 // stg_apply_interp_info pointer and a pointer to
827 // the BCO
828 size_words = BCO_BITMAP_SIZE(obj) + 2;
829 new_aps = (StgAP_STACK *) allocate (AP_STACK_sizeW(size_words));
830 SET_HDR(new_aps,&stg_AP_STACK_info,CCS_SYSTEM);
831 new_aps->size = size_words;
832 new_aps->fun = &stg_dummy_ret_closure;
833
834 // fill in the payload of the AP_STACK
835 new_aps->payload[0] = (StgClosure *)&stg_apply_interp_info;
836 new_aps->payload[1] = (StgClosure *)obj;
837
838 // copy the contents of the top stack frame into the AP_STACK
839 for (i = 2; i < size_words; i++)
840 {
841 new_aps->payload[i] = (StgClosure *)Sp[i-2];
842 }
843
844 // prepare the stack so that we can call the
845 // rts_breakpoint_io_action and ensure that the stack is
846 // in a reasonable state for the GC and so that
847 // execution of this BCO can continue when we resume
848 ioAction = (StgClosure *) deRefStablePtr (rts_breakpoint_io_action);
849 Sp -= 8;
850 Sp[7] = (W_)obj;
851 Sp[6] = (W_)&stg_apply_interp_info;
852 Sp[5] = (W_)new_aps; // the AP_STACK
853 Sp[4] = (W_)BCO_PTR(arg3_freeVars); // the info about local vars of the breakpoint
854 Sp[3] = (W_)False_closure; // True <=> a breakpoint
855 Sp[2] = (W_)&stg_ap_pppv_info;
856 Sp[1] = (W_)ioAction; // apply the IO action to its two arguments above
857 Sp[0] = (W_)&stg_enter_info; // get ready to run the IO action
858
859 // set the flag in the TSO to say that we are now
860 // stopping at a breakpoint so that when we resume
861 // we don't stop on the same breakpoint that we
862 // already stopped at just now
863 cap->r.rCurrentTSO->flags |= TSO_STOPPED_ON_BREAKPOINT;
864
865 // stop this thread and return to the scheduler -
866 // eventually we will come back and the IO action on
867 // the top of the stack will be executed
868 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
869 }
870 }
871 // record that this thread is not stopped at a breakpoint anymore
872 cap->r.rCurrentTSO->flags &= ~TSO_STOPPED_ON_BREAKPOINT;
873
874 // continue normal execution of the byte code instructions
875 goto nextInsn;
876 }
877
878 case bci_STKCHECK: {
879 // Explicit stack check at the beginning of a function
880 // *only* (stack checks in case alternatives are
881 // propagated to the enclosing function).
882 StgWord stk_words_reqd = BCO_GET_LARGE_ARG + 1;
883 if (Sp - stk_words_reqd < SpLim) {
884 Sp -= 2;
885 Sp[1] = (W_)obj;
886 Sp[0] = (W_)&stg_apply_interp_info;
887 RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow);
888 } else {
889 goto nextInsn;
890 }
891 }
892
893 case bci_PUSH_L: {
894 int o1 = BCO_NEXT;
895 Sp[-1] = Sp[o1];
896 Sp--;
897 goto nextInsn;
898 }
899
900 case bci_PUSH_LL: {
901 int o1 = BCO_NEXT;
902 int o2 = BCO_NEXT;
903 Sp[-1] = Sp[o1];
904 Sp[-2] = Sp[o2];
905 Sp -= 2;
906 goto nextInsn;
907 }
908
909 case bci_PUSH_LLL: {
910 int o1 = BCO_NEXT;
911 int o2 = BCO_NEXT;
912 int o3 = BCO_NEXT;
913 Sp[-1] = Sp[o1];
914 Sp[-2] = Sp[o2];
915 Sp[-3] = Sp[o3];
916 Sp -= 3;
917 goto nextInsn;
918 }
919
920 case bci_PUSH_G: {
921 int o1 = BCO_NEXT;
922 Sp[-1] = BCO_PTR(o1);
923 Sp -= 1;
924 goto nextInsn;
925 }
926
927 case bci_PUSH_ALTS: {
928 int o_bco = BCO_NEXT;
929 Sp[-2] = (W_)&stg_ctoi_R1p_info;
930 Sp[-1] = BCO_PTR(o_bco);
931 Sp -= 2;
932 goto nextInsn;
933 }
934
935 case bci_PUSH_ALTS_P: {
936 int o_bco = BCO_NEXT;
937 Sp[-2] = (W_)&stg_ctoi_R1unpt_info;
938 Sp[-1] = BCO_PTR(o_bco);
939 Sp -= 2;
940 goto nextInsn;
941 }
942
943 case bci_PUSH_ALTS_N: {
944 int o_bco = BCO_NEXT;
945 Sp[-2] = (W_)&stg_ctoi_R1n_info;
946 Sp[-1] = BCO_PTR(o_bco);
947 Sp -= 2;
948 goto nextInsn;
949 }
950
951 case bci_PUSH_ALTS_F: {
952 int o_bco = BCO_NEXT;
953 Sp[-2] = (W_)&stg_ctoi_F1_info;
954 Sp[-1] = BCO_PTR(o_bco);
955 Sp -= 2;
956 goto nextInsn;
957 }
958
959 case bci_PUSH_ALTS_D: {
960 int o_bco = BCO_NEXT;
961 Sp[-2] = (W_)&stg_ctoi_D1_info;
962 Sp[-1] = BCO_PTR(o_bco);
963 Sp -= 2;
964 goto nextInsn;
965 }
966
967 case bci_PUSH_ALTS_L: {
968 int o_bco = BCO_NEXT;
969 Sp[-2] = (W_)&stg_ctoi_L1_info;
970 Sp[-1] = BCO_PTR(o_bco);
971 Sp -= 2;
972 goto nextInsn;
973 }
974
975 case bci_PUSH_ALTS_V: {
976 int o_bco = BCO_NEXT;
977 Sp[-2] = (W_)&stg_ctoi_V_info;
978 Sp[-1] = BCO_PTR(o_bco);
979 Sp -= 2;
980 goto nextInsn;
981 }
982
983 case bci_PUSH_APPLY_N:
984 Sp--; Sp[0] = (W_)&stg_ap_n_info;
985 goto nextInsn;
986 case bci_PUSH_APPLY_V:
987 Sp--; Sp[0] = (W_)&stg_ap_v_info;
988 goto nextInsn;
989 case bci_PUSH_APPLY_F:
990 Sp--; Sp[0] = (W_)&stg_ap_f_info;
991 goto nextInsn;
992 case bci_PUSH_APPLY_D:
993 Sp--; Sp[0] = (W_)&stg_ap_d_info;
994 goto nextInsn;
995 case bci_PUSH_APPLY_L:
996 Sp--; Sp[0] = (W_)&stg_ap_l_info;
997 goto nextInsn;
998 case bci_PUSH_APPLY_P:
999 Sp--; Sp[0] = (W_)&stg_ap_p_info;
1000 goto nextInsn;
1001 case bci_PUSH_APPLY_PP:
1002 Sp--; Sp[0] = (W_)&stg_ap_pp_info;
1003 goto nextInsn;
1004 case bci_PUSH_APPLY_PPP:
1005 Sp--; Sp[0] = (W_)&stg_ap_ppp_info;
1006 goto nextInsn;
1007 case bci_PUSH_APPLY_PPPP:
1008 Sp--; Sp[0] = (W_)&stg_ap_pppp_info;
1009 goto nextInsn;
1010 case bci_PUSH_APPLY_PPPPP:
1011 Sp--; Sp[0] = (W_)&stg_ap_ppppp_info;
1012 goto nextInsn;
1013 case bci_PUSH_APPLY_PPPPPP:
1014 Sp--; Sp[0] = (W_)&stg_ap_pppppp_info;
1015 goto nextInsn;
1016
1017 case bci_PUSH_UBX: {
1018 int i;
1019 int o_lits = BCO_NEXT;
1020 int n_words = BCO_NEXT;
1021 Sp -= n_words;
1022 for (i = 0; i < n_words; i++) {
1023 Sp[i] = (W_)BCO_LIT(o_lits+i);
1024 }
1025 goto nextInsn;
1026 }
1027
1028 case bci_SLIDE: {
1029 int n = BCO_NEXT;
1030 int by = BCO_NEXT;
1031 /* a_1, .. a_n, b_1, .. b_by, s => a_1, .. a_n, s */
1032 while(--n >= 0) {
1033 Sp[n+by] = Sp[n];
1034 }
1035 Sp += by;
1036 INTERP_TICK(it_slides);
1037 goto nextInsn;
1038 }
1039
1040 case bci_ALLOC_AP: {
1041 StgAP* ap;
1042 int n_payload = BCO_NEXT;
1043 ap = (StgAP*)allocate(AP_sizeW(n_payload));
1044 Sp[-1] = (W_)ap;
1045 ap->n_args = n_payload;
1046 SET_HDR(ap, &stg_AP_info, CCS_SYSTEM/*ToDo*/)
1047 Sp --;
1048 goto nextInsn;
1049 }
1050
1051 case bci_ALLOC_PAP: {
1052 StgPAP* pap;
1053 int arity = BCO_NEXT;
1054 int n_payload = BCO_NEXT;
1055 pap = (StgPAP*)allocate(PAP_sizeW(n_payload));
1056 Sp[-1] = (W_)pap;
1057 pap->n_args = n_payload;
1058 pap->arity = arity;
1059 SET_HDR(pap, &stg_PAP_info, CCS_SYSTEM/*ToDo*/)
1060 Sp --;
1061 goto nextInsn;
1062 }
1063
1064 case bci_MKAP: {
1065 int i;
1066 int stkoff = BCO_NEXT;
1067 int n_payload = BCO_NEXT;
1068 StgAP* ap = (StgAP*)Sp[stkoff];
1069 ASSERT((int)ap->n_args == n_payload);
1070 ap->fun = (StgClosure*)Sp[0];
1071
1072 // The function should be a BCO, and its bitmap should
1073 // cover the payload of the AP correctly.
1074 ASSERT(get_itbl(ap->fun)->type == BCO
1075 && BCO_BITMAP_SIZE(ap->fun) == ap->n_args);
1076
1077 for (i = 0; i < n_payload; i++)
1078 ap->payload[i] = (StgClosure*)Sp[i+1];
1079 Sp += n_payload+1;
1080 IF_DEBUG(interpreter,
1081 debugBelch("\tBuilt ");
1082 printObj((StgClosure*)ap);
1083 );
1084 goto nextInsn;
1085 }
1086
1087 case bci_MKPAP: {
1088 int i;
1089 int stkoff = BCO_NEXT;
1090 int n_payload = BCO_NEXT;
1091 StgPAP* pap = (StgPAP*)Sp[stkoff];
1092 ASSERT((int)pap->n_args == n_payload);
1093 pap->fun = (StgClosure*)Sp[0];
1094
1095 // The function should be a BCO
1096 ASSERT(get_itbl(pap->fun)->type == BCO);
1097
1098 for (i = 0; i < n_payload; i++)
1099 pap->payload[i] = (StgClosure*)Sp[i+1];
1100 Sp += n_payload+1;
1101 IF_DEBUG(interpreter,
1102 debugBelch("\tBuilt ");
1103 printObj((StgClosure*)pap);
1104 );
1105 goto nextInsn;
1106 }
1107
1108 case bci_UNPACK: {
1109 /* Unpack N ptr words from t.o.s constructor */
1110 int i;
1111 int n_words = BCO_NEXT;
1112 StgClosure* con = (StgClosure*)Sp[0];
1113 Sp -= n_words;
1114 for (i = 0; i < n_words; i++) {
1115 Sp[i] = (W_)con->payload[i];
1116 }
1117 goto nextInsn;
1118 }
1119
1120 case bci_PACK: {
1121 int i;
1122 int o_itbl = BCO_NEXT;
1123 int n_words = BCO_NEXT;
1124 StgInfoTable* itbl = INFO_PTR_TO_STRUCT(BCO_LIT(o_itbl));
1125 int request = CONSTR_sizeW( itbl->layout.payload.ptrs,
1126 itbl->layout.payload.nptrs );
1127 StgClosure* con = (StgClosure*)allocate_NONUPD(request);
1128 ASSERT( itbl->layout.payload.ptrs + itbl->layout.payload.nptrs > 0);
1129 SET_HDR(con, (StgInfoTable*)BCO_LIT(o_itbl), CCS_SYSTEM/*ToDo*/);
1130 for (i = 0; i < n_words; i++) {
1131 con->payload[i] = (StgClosure*)Sp[i];
1132 }
1133 Sp += n_words;
1134 Sp --;
1135 Sp[0] = (W_)con;
1136 IF_DEBUG(interpreter,
1137 debugBelch("\tBuilt ");
1138 printObj((StgClosure*)con);
1139 );
1140 goto nextInsn;
1141 }
1142
1143 case bci_TESTLT_P: {
1144 unsigned int discr = BCO_NEXT;
1145 int failto = BCO_NEXT;
1146 StgClosure* con = (StgClosure*)Sp[0];
1147 if (GET_TAG(con) >= discr) {
1148 bciPtr = failto;
1149 }
1150 goto nextInsn;
1151 }
1152
1153 case bci_TESTEQ_P: {
1154 unsigned int discr = BCO_NEXT;
1155 int failto = BCO_NEXT;
1156 StgClosure* con = (StgClosure*)Sp[0];
1157 if (GET_TAG(con) != discr) {
1158 bciPtr = failto;
1159 }
1160 goto nextInsn;
1161 }
1162
1163 case bci_TESTLT_I: {
1164 // There should be an Int at Sp[1], and an info table at Sp[0].
1165 int discr = BCO_NEXT;
1166 int failto = BCO_NEXT;
1167 I_ stackInt = (I_)Sp[1];
1168 if (stackInt >= (I_)BCO_LIT(discr))
1169 bciPtr = failto;
1170 goto nextInsn;
1171 }
1172
1173 case bci_TESTEQ_I: {
1174 // There should be an Int at Sp[1], and an info table at Sp[0].
1175 int discr = BCO_NEXT;
1176 int failto = BCO_NEXT;
1177 I_ stackInt = (I_)Sp[1];
1178 if (stackInt != (I_)BCO_LIT(discr)) {
1179 bciPtr = failto;
1180 }
1181 goto nextInsn;
1182 }
1183
1184 case bci_TESTLT_D: {
1185 // There should be a Double at Sp[1], and an info table at Sp[0].
1186 int discr = BCO_NEXT;
1187 int failto = BCO_NEXT;
1188 StgDouble stackDbl, discrDbl;
1189 stackDbl = PK_DBL( & Sp[1] );
1190 discrDbl = PK_DBL( & BCO_LIT(discr) );
1191 if (stackDbl >= discrDbl) {
1192 bciPtr = failto;
1193 }
1194 goto nextInsn;
1195 }
1196
1197 case bci_TESTEQ_D: {
1198 // There should be a Double at Sp[1], and an info table at Sp[0].
1199 int discr = BCO_NEXT;
1200 int failto = BCO_NEXT;
1201 StgDouble stackDbl, discrDbl;
1202 stackDbl = PK_DBL( & Sp[1] );
1203 discrDbl = PK_DBL( & BCO_LIT(discr) );
1204 if (stackDbl != discrDbl) {
1205 bciPtr = failto;
1206 }
1207 goto nextInsn;
1208 }
1209
1210 case bci_TESTLT_F: {
1211 // There should be a Float at Sp[1], and an info table at Sp[0].
1212 int discr = BCO_NEXT;
1213 int failto = BCO_NEXT;
1214 StgFloat stackFlt, discrFlt;
1215 stackFlt = PK_FLT( & Sp[1] );
1216 discrFlt = PK_FLT( & BCO_LIT(discr) );
1217 if (stackFlt >= discrFlt) {
1218 bciPtr = failto;
1219 }
1220 goto nextInsn;
1221 }
1222
1223 case bci_TESTEQ_F: {
1224 // There should be a Float at Sp[1], and an info table at Sp[0].
1225 int discr = BCO_NEXT;
1226 int failto = BCO_NEXT;
1227 StgFloat stackFlt, discrFlt;
1228 stackFlt = PK_FLT( & Sp[1] );
1229 discrFlt = PK_FLT( & BCO_LIT(discr) );
1230 if (stackFlt != discrFlt) {
1231 bciPtr = failto;
1232 }
1233 goto nextInsn;
1234 }
1235
1236 // Control-flow ish things
1237 case bci_ENTER:
1238 // Context-switch check. We put it here to ensure that
1239 // the interpreter has done at least *some* work before
1240 // context switching: sometimes the scheduler can invoke
1241 // the interpreter with context_switch == 1, particularly
1242 // if the -C0 flag has been given on the cmd line.
1243 if (context_switch) {
1244 Sp--; Sp[0] = (W_)&stg_enter_info;
1245 RETURN_TO_SCHEDULER(ThreadInterpret, ThreadYielding);
1246 }
1247 goto eval;
1248
1249 case bci_RETURN:
1250 obj = (StgClosure *)Sp[0];
1251 Sp++;
1252 goto do_return;
1253
1254 case bci_RETURN_P:
1255 Sp--;
1256 Sp[0] = (W_)&stg_gc_unpt_r1_info;
1257 goto do_return_unboxed;
1258 case bci_RETURN_N:
1259 Sp--;
1260 Sp[0] = (W_)&stg_gc_unbx_r1_info;
1261 goto do_return_unboxed;
1262 case bci_RETURN_F:
1263 Sp--;
1264 Sp[0] = (W_)&stg_gc_f1_info;
1265 goto do_return_unboxed;
1266 case bci_RETURN_D:
1267 Sp--;
1268 Sp[0] = (W_)&stg_gc_d1_info;
1269 goto do_return_unboxed;
1270 case bci_RETURN_L:
1271 Sp--;
1272 Sp[0] = (W_)&stg_gc_l1_info;
1273 goto do_return_unboxed;
1274 case bci_RETURN_V:
1275 Sp--;
1276 Sp[0] = (W_)&stg_gc_void_info;
1277 goto do_return_unboxed;
1278
1279 case bci_SWIZZLE: {
1280 int stkoff = BCO_NEXT;
1281 signed short n = (signed short)(BCO_NEXT);
1282 Sp[stkoff] += (W_)n;
1283 goto nextInsn;
1284 }
1285
1286 case bci_CCALL: {
1287 void *tok;
1288 int stk_offset = BCO_NEXT;
1289 int o_itbl = BCO_NEXT;
1290 void(*marshall_fn)(void*) = (void (*)(void*))BCO_LIT(o_itbl);
1291 int ret_dyn_size =
1292 RET_DYN_BITMAP_SIZE + RET_DYN_NONPTR_REGS_SIZE
1293 + sizeofW(StgRetDyn);
1294
1295 #ifdef THREADED_RTS
1296 // Threaded RTS:
1297 // Arguments on the TSO stack are not good, because garbage
1298 // collection might move the TSO as soon as we call
1299 // suspendThread below.
1300
1301 W_ arguments[stk_offset];
1302
1303 memcpy(arguments, Sp, sizeof(W_) * stk_offset);
1304 #endif
1305
1306 // Restore the Haskell thread's current value of errno
1307 errno = cap->r.rCurrentTSO->saved_errno;
1308
1309 // There are a bunch of non-ptr words on the stack (the
1310 // ccall args, the ccall fun address and space for the
1311 // result), which we need to cover with an info table
1312 // since we might GC during this call.
1313 //
1314 // We know how many (non-ptr) words there are before the
1315 // next valid stack frame: it is the stk_offset arg to the
1316 // CCALL instruction. So we build a RET_DYN stack frame
1317 // on the stack frame to describe this chunk of stack.
1318 //
1319 Sp -= ret_dyn_size;
1320 ((StgRetDyn *)Sp)->liveness = NO_PTRS | N_NONPTRS(stk_offset);
1321 ((StgRetDyn *)Sp)->info = (StgInfoTable *)&stg_gc_gen_info;
1322
1323 SAVE_STACK_POINTERS;
1324 tok = suspendThread(&cap->r);
1325
1326 #ifndef THREADED_RTS
1327 // Careful:
1328 // suspendThread might have shifted the stack
1329 // around (stack squeezing), so we have to grab the real
1330 // Sp out of the TSO to find the ccall args again.
1331
1332 marshall_fn ( (void*)(cap->r.rCurrentTSO->sp + ret_dyn_size) );
1333 #else
1334 // Threaded RTS:
1335 // We already made a copy of the arguments above.
1336
1337 marshall_fn ( arguments );
1338 #endif
1339
1340 // And restart the thread again, popping the RET_DYN frame.
1341 cap = (Capability *)((void *)((unsigned char*)resumeThread(tok) - sizeof(StgFunTable)));
1342 LOAD_STACK_POINTERS;
1343 Sp += ret_dyn_size;
1344
1345 // Save the Haskell thread's current value of errno
1346 cap->r.rCurrentTSO->saved_errno = errno;
1347
1348 #ifdef THREADED_RTS
1349 // Threaded RTS:
1350 // Copy the "arguments", which might include a return value,
1351 // back to the TSO stack. It would of course be enough to
1352 // just copy the return value, but we don't know the offset.
1353 memcpy(Sp, arguments, sizeof(W_) * stk_offset);
1354 #endif
1355
1356 goto nextInsn;
1357 }
1358
1359 case bci_JMP: {
1360 /* BCO_NEXT modifies bciPtr, so be conservative. */
1361 int nextpc = BCO_NEXT;
1362 bciPtr = nextpc;
1363 goto nextInsn;
1364 }
1365
1366 case bci_CASEFAIL:
1367 barf("interpretBCO: hit a CASEFAIL");
1368
1369 // Errors
1370 default:
1371 barf("interpretBCO: unknown or unimplemented opcode %d",
1372 (int)BCO_NEXT);
1373
1374 } /* switch on opcode */
1375 }
1376 }
1377
1378 barf("interpretBCO: fell off end of the interpreter");
1379 }
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