Pointer Tagging
[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 = UNTAG_CLOSURE((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 obj = UNTAG_CLOSURE(obj);
248 INTERP_TICK(it_total_evals);
249
250 IF_DEBUG(interpreter,
251 debugBelch(
252 "\n---------------------------------------------------------------\n");
253 debugBelch("Evaluating: "); printObj(obj);
254 debugBelch("Sp = %p\n", Sp);
255 debugBelch("\n" );
256
257 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
258 debugBelch("\n\n");
259 );
260
261 IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size));
262
263 switch ( get_itbl(obj)->type ) {
264
265 case IND:
266 case IND_OLDGEN:
267 case IND_PERM:
268 case IND_OLDGEN_PERM:
269 case IND_STATIC:
270 {
271 obj = ((StgInd*)obj)->indirectee;
272 goto eval_obj;
273 }
274
275 case CONSTR:
276 case CONSTR_1_0:
277 case CONSTR_0_1:
278 case CONSTR_2_0:
279 case CONSTR_1_1:
280 case CONSTR_0_2:
281 case CONSTR_STATIC:
282 case CONSTR_NOCAF_STATIC:
283 case FUN:
284 case FUN_1_0:
285 case FUN_0_1:
286 case FUN_2_0:
287 case FUN_1_1:
288 case FUN_0_2:
289 case FUN_STATIC:
290 case PAP:
291 // already in WHNF
292 break;
293
294 case BCO:
295 {
296 ASSERT(((StgBCO *)obj)->arity > 0);
297 break;
298 }
299
300 case AP: /* Copied from stg_AP_entry. */
301 {
302 nat i, words;
303 StgAP *ap;
304
305 ap = (StgAP*)obj;
306 words = ap->n_args;
307
308 // Stack check
309 if (Sp - (words+sizeofW(StgUpdateFrame)) < SpLim) {
310 Sp -= 2;
311 Sp[1] = (W_)obj;
312 Sp[0] = (W_)&stg_enter_info;
313 RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow);
314 }
315
316 /* Ok; we're safe. Party on. Push an update frame. */
317 Sp -= sizeofW(StgUpdateFrame);
318 {
319 StgUpdateFrame *__frame;
320 __frame = (StgUpdateFrame *)Sp;
321 SET_INFO(__frame, (StgInfoTable *)&stg_upd_frame_info);
322 __frame->updatee = (StgClosure *)(ap);
323 }
324
325 /* Reload the stack */
326 Sp -= words;
327 for (i=0; i < words; i++) {
328 Sp[i] = (W_)ap->payload[i];
329 }
330
331 obj = UNTAG_CLOSURE((StgClosure*)ap->fun);
332 ASSERT(get_itbl(obj)->type == BCO);
333 goto run_BCO_fun;
334 }
335
336 default:
337 #ifdef INTERP_STATS
338 {
339 int j;
340
341 j = get_itbl(obj)->type;
342 ASSERT(j >= 0 && j < N_CLOSURE_TYPES);
343 it_unknown_entries[j]++;
344 it_total_unknown_entries++;
345 }
346 #endif
347 {
348 // Can't handle this object; yield to scheduler
349 IF_DEBUG(interpreter,
350 debugBelch("evaluating unknown closure -- yielding to sched\n");
351 printObj(obj);
352 );
353 Sp -= 2;
354 Sp[1] = (W_)obj;
355 Sp[0] = (W_)&stg_enter_info;
356 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
357 }
358 }
359
360 // ------------------------------------------------------------------------
361 // We now have an evaluated object (obj). The next thing to
362 // do is return it to the stack frame on top of the stack.
363 do_return:
364 ASSERT(closure_HNF(obj));
365
366 IF_DEBUG(interpreter,
367 debugBelch(
368 "\n---------------------------------------------------------------\n");
369 debugBelch("Returning: "); printObj(obj);
370 debugBelch("Sp = %p\n", Sp);
371 debugBelch("\n" );
372 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
373 debugBelch("\n\n");
374 );
375
376 IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size));
377
378 switch (get_itbl((StgClosure *)Sp)->type) {
379
380 case RET_SMALL: {
381 const StgInfoTable *info;
382
383 // NOTE: not using get_itbl().
384 info = ((StgClosure *)Sp)->header.info;
385 if (info == (StgInfoTable *)&stg_ap_v_info) {
386 n = 1; m = 0; goto do_apply;
387 }
388 if (info == (StgInfoTable *)&stg_ap_f_info) {
389 n = 1; m = 1; goto do_apply;
390 }
391 if (info == (StgInfoTable *)&stg_ap_d_info) {
392 n = 1; m = sizeofW(StgDouble); goto do_apply;
393 }
394 if (info == (StgInfoTable *)&stg_ap_l_info) {
395 n = 1; m = sizeofW(StgInt64); goto do_apply;
396 }
397 if (info == (StgInfoTable *)&stg_ap_n_info) {
398 n = 1; m = 1; goto do_apply;
399 }
400 if (info == (StgInfoTable *)&stg_ap_p_info) {
401 n = 1; m = 1; goto do_apply;
402 }
403 if (info == (StgInfoTable *)&stg_ap_pp_info) {
404 n = 2; m = 2; goto do_apply;
405 }
406 if (info == (StgInfoTable *)&stg_ap_ppp_info) {
407 n = 3; m = 3; goto do_apply;
408 }
409 if (info == (StgInfoTable *)&stg_ap_pppp_info) {
410 n = 4; m = 4; goto do_apply;
411 }
412 if (info == (StgInfoTable *)&stg_ap_ppppp_info) {
413 n = 5; m = 5; goto do_apply;
414 }
415 if (info == (StgInfoTable *)&stg_ap_pppppp_info) {
416 n = 6; m = 6; goto do_apply;
417 }
418 goto do_return_unrecognised;
419 }
420
421 case UPDATE_FRAME:
422 // Returning to an update frame: do the update, pop the update
423 // frame, and continue with the next stack frame.
424 INTERP_TICK(it_retto_UPDATE);
425 UPD_IND(((StgUpdateFrame *)Sp)->updatee, obj);
426 Sp += sizeofW(StgUpdateFrame);
427 goto do_return;
428
429 case RET_BCO:
430 // Returning to an interpreted continuation: put the object on
431 // the stack, and start executing the BCO.
432 INTERP_TICK(it_retto_BCO);
433 Sp--;
434 Sp[0] = (W_)obj;
435 obj = (StgClosure*)Sp[2];
436 ASSERT(get_itbl(obj)->type == BCO);
437 goto run_BCO_return;
438
439 default:
440 do_return_unrecognised:
441 {
442 // Can't handle this return address; yield to scheduler
443 INTERP_TICK(it_retto_other);
444 IF_DEBUG(interpreter,
445 debugBelch("returning to unknown frame -- yielding to sched\n");
446 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
447 );
448 Sp -= 2;
449 Sp[1] = (W_)obj;
450 Sp[0] = (W_)&stg_enter_info;
451 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
452 }
453 }
454
455 // -------------------------------------------------------------------------
456 // Returning an unboxed value. The stack looks like this:
457 //
458 // | .... |
459 // +---------------+
460 // | fv2 |
461 // +---------------+
462 // | fv1 |
463 // +---------------+
464 // | BCO |
465 // +---------------+
466 // | stg_ctoi_ret_ |
467 // +---------------+
468 // | retval |
469 // +---------------+
470 // | XXXX_info |
471 // +---------------+
472 //
473 // where XXXX_info is one of the stg_gc_unbx_r1_info family.
474 //
475 // We're only interested in the case when the real return address
476 // is a BCO; otherwise we'll return to the scheduler.
477
478 do_return_unboxed:
479 {
480 int offset;
481
482 ASSERT( Sp[0] == (W_)&stg_gc_unbx_r1_info
483 || Sp[0] == (W_)&stg_gc_unpt_r1_info
484 || Sp[0] == (W_)&stg_gc_f1_info
485 || Sp[0] == (W_)&stg_gc_d1_info
486 || Sp[0] == (W_)&stg_gc_l1_info
487 || Sp[0] == (W_)&stg_gc_void_info // VoidRep
488 );
489
490 // get the offset of the stg_ctoi_ret_XXX itbl
491 offset = stack_frame_sizeW((StgClosure *)Sp);
492
493 switch (get_itbl((StgClosure *)Sp+offset)->type) {
494
495 case RET_BCO:
496 // Returning to an interpreted continuation: put the object on
497 // the stack, and start executing the BCO.
498 INTERP_TICK(it_retto_BCO);
499 obj = (StgClosure*)Sp[offset+1];
500 ASSERT(get_itbl(obj)->type == BCO);
501 goto run_BCO_return_unboxed;
502
503 default:
504 {
505 // Can't handle this return address; yield to scheduler
506 INTERP_TICK(it_retto_other);
507 IF_DEBUG(interpreter,
508 debugBelch("returning to unknown frame -- yielding to sched\n");
509 printStackChunk(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size);
510 );
511 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
512 }
513 }
514 }
515 // not reached.
516
517
518 // -------------------------------------------------------------------------
519 // Application...
520
521 do_apply:
522 // we have a function to apply (obj), and n arguments taking up m
523 // words on the stack. The info table (stg_ap_pp_info or whatever)
524 // is on top of the arguments on the stack.
525 {
526 switch (get_itbl(obj)->type) {
527
528 case PAP: {
529 StgPAP *pap;
530 nat i, arity;
531
532 pap = (StgPAP *)obj;
533
534 // we only cope with PAPs whose function is a BCO
535 if (get_itbl(UNTAG_CLOSURE(pap->fun))->type != BCO) {
536 goto defer_apply_to_sched;
537 }
538
539 Sp++;
540 arity = pap->arity;
541 ASSERT(arity > 0);
542 if (arity < n) {
543 // n must be greater than 1, and the only kinds of
544 // application we support with more than one argument
545 // are all pointers...
546 //
547 // Shuffle the args for this function down, and put
548 // the appropriate info table in the gap.
549 for (i = 0; i < arity; i++) {
550 Sp[(int)i-1] = Sp[i];
551 // ^^^^^ careful, i-1 might be negative, but i in unsigned
552 }
553 Sp[arity-1] = app_ptrs_itbl[n-arity-1];
554 Sp--;
555 // unpack the PAP's arguments onto the stack
556 Sp -= pap->n_args;
557 for (i = 0; i < pap->n_args; i++) {
558 Sp[i] = (W_)pap->payload[i];
559 }
560 obj = UNTAG_CLOSURE(pap->fun);
561 goto run_BCO_fun;
562 }
563 else if (arity == n) {
564 Sp -= pap->n_args;
565 for (i = 0; i < pap->n_args; i++) {
566 Sp[i] = (W_)pap->payload[i];
567 }
568 obj = UNTAG_CLOSURE(pap->fun);
569 goto run_BCO_fun;
570 }
571 else /* arity > n */ {
572 // build a new PAP and return it.
573 StgPAP *new_pap;
574 new_pap = (StgPAP *)allocate(PAP_sizeW(pap->n_args + m));
575 SET_HDR(new_pap,&stg_PAP_info,CCCS);
576 new_pap->arity = pap->arity - n;
577 new_pap->n_args = pap->n_args + m;
578 new_pap->fun = pap->fun;
579 for (i = 0; i < pap->n_args; i++) {
580 new_pap->payload[i] = pap->payload[i];
581 }
582 for (i = 0; i < m; i++) {
583 new_pap->payload[pap->n_args + i] = (StgClosure *)Sp[i];
584 }
585 obj = (StgClosure *)new_pap;
586 Sp += m;
587 goto do_return;
588 }
589 }
590
591 case BCO: {
592 nat arity, i;
593
594 Sp++;
595 arity = ((StgBCO *)obj)->arity;
596 ASSERT(arity > 0);
597 if (arity < n) {
598 // n must be greater than 1, and the only kinds of
599 // application we support with more than one argument
600 // are all pointers...
601 //
602 // Shuffle the args for this function down, and put
603 // the appropriate info table in the gap.
604 for (i = 0; i < arity; i++) {
605 Sp[(int)i-1] = Sp[i];
606 // ^^^^^ careful, i-1 might be negative, but i in unsigned
607 }
608 Sp[arity-1] = app_ptrs_itbl[n-arity-1];
609 Sp--;
610 goto run_BCO_fun;
611 }
612 else if (arity == n) {
613 goto run_BCO_fun;
614 }
615 else /* arity > n */ {
616 // build a PAP and return it.
617 StgPAP *pap;
618 nat i;
619 pap = (StgPAP *)allocate(PAP_sizeW(m));
620 SET_HDR(pap, &stg_PAP_info,CCCS);
621 pap->arity = arity - n;
622 pap->fun = obj;
623 pap->n_args = m;
624 for (i = 0; i < m; i++) {
625 pap->payload[i] = (StgClosure *)Sp[i];
626 }
627 obj = (StgClosure *)pap;
628 Sp += m;
629 goto do_return;
630 }
631 }
632
633 // No point in us applying machine-code functions
634 default:
635 defer_apply_to_sched:
636 Sp -= 2;
637 Sp[1] = (W_)obj;
638 Sp[0] = (W_)&stg_enter_info;
639 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
640 }
641
642 // ------------------------------------------------------------------------
643 // Ok, we now have a bco (obj), and its arguments are all on the
644 // stack. We can start executing the byte codes.
645 //
646 // The stack is in one of two states. First, if this BCO is a
647 // function:
648 //
649 // | .... |
650 // +---------------+
651 // | arg2 |
652 // +---------------+
653 // | arg1 |
654 // +---------------+
655 //
656 // Second, if this BCO is a continuation:
657 //
658 // | .... |
659 // +---------------+
660 // | fv2 |
661 // +---------------+
662 // | fv1 |
663 // +---------------+
664 // | BCO |
665 // +---------------+
666 // | stg_ctoi_ret_ |
667 // +---------------+
668 // | retval |
669 // +---------------+
670 //
671 // where retval is the value being returned to this continuation.
672 // In the event of a stack check, heap check, or context switch,
673 // we need to leave the stack in a sane state so the garbage
674 // collector can find all the pointers.
675 //
676 // (1) BCO is a function: the BCO's bitmap describes the
677 // pointerhood of the arguments.
678 //
679 // (2) BCO is a continuation: BCO's bitmap describes the
680 // pointerhood of the free variables.
681 //
682 // Sadly we have three different kinds of stack/heap/cswitch check
683 // to do:
684
685
686 run_BCO_return:
687 // Heap check
688 if (doYouWantToGC()) {
689 Sp--; Sp[0] = (W_)&stg_enter_info;
690 RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow);
691 }
692 // Stack checks aren't necessary at return points, the stack use
693 // is aggregated into the enclosing function entry point.
694
695 goto run_BCO;
696
697 run_BCO_return_unboxed:
698 // Heap check
699 if (doYouWantToGC()) {
700 RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow);
701 }
702 // Stack checks aren't necessary at return points, the stack use
703 // is aggregated into the enclosing function entry point.
704
705 goto run_BCO;
706
707 run_BCO_fun:
708 IF_DEBUG(sanity,
709 Sp -= 2;
710 Sp[1] = (W_)obj;
711 Sp[0] = (W_)&stg_apply_interp_info;
712 checkStackChunk(Sp,SpLim);
713 Sp += 2;
714 );
715
716 // Heap check
717 if (doYouWantToGC()) {
718 Sp -= 2;
719 Sp[1] = (W_)obj;
720 Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really
721 RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow);
722 }
723
724 // Stack check
725 if (Sp - INTERP_STACK_CHECK_THRESH < SpLim) {
726 Sp -= 2;
727 Sp[1] = (W_)obj;
728 Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really
729 RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow);
730 }
731
732 goto run_BCO;
733
734 // Now, actually interpret the BCO... (no returning to the
735 // scheduler again until the stack is in an orderly state).
736 run_BCO:
737 INTERP_TICK(it_BCO_entries);
738 {
739 register int bciPtr = 1; /* instruction pointer */
740 register StgWord16 bci;
741 register StgBCO* bco = (StgBCO*)obj;
742 register StgWord16* instrs = (StgWord16*)(bco->instrs->payload);
743 register StgWord* literals = (StgWord*)(&bco->literals->payload[0]);
744 register StgPtr* ptrs = (StgPtr*)(&bco->ptrs->payload[0]);
745
746 #ifdef INTERP_STATS
747 it_lastopc = 0; /* no opcode */
748 #endif
749
750 nextInsn:
751 ASSERT(bciPtr <= instrs[0]);
752 IF_DEBUG(interpreter,
753 //if (do_print_stack) {
754 //debugBelch("\n-- BEGIN stack\n");
755 //printStack(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size,iSu);
756 //debugBelch("-- END stack\n\n");
757 //}
758 debugBelch("Sp = %p pc = %d ", Sp, bciPtr);
759 disInstr(bco,bciPtr);
760 if (0) { int i;
761 debugBelch("\n");
762 for (i = 8; i >= 0; i--) {
763 debugBelch("%d %p\n", i, (StgPtr)(*(Sp+i)));
764 }
765 debugBelch("\n");
766 }
767 //if (do_print_stack) checkStack(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size,iSu);
768 );
769
770
771 INTERP_TICK(it_insns);
772
773 #ifdef INTERP_STATS
774 ASSERT( (int)instrs[bciPtr] >= 0 && (int)instrs[bciPtr] < 27 );
775 it_ofreq[ (int)instrs[bciPtr] ] ++;
776 it_oofreq[ it_lastopc ][ (int)instrs[bciPtr] ] ++;
777 it_lastopc = (int)instrs[bciPtr];
778 #endif
779
780 bci = BCO_NEXT;
781 /* We use the high 8 bits for flags, only the highest of which is
782 * currently allocated */
783 ASSERT((bci & 0xFF00) == (bci & 0x8000));
784
785 switch (bci & 0xFF) {
786
787 /* check for a breakpoint on the beginning of a let binding */
788 case bci_BRK_FUN:
789 {
790 int arg1_brk_array, arg2_array_index, arg3_freeVars;
791 StgArrWords *breakPoints;
792 int returning_from_break; // are we resuming execution from a breakpoint?
793 // if yes, then don't break this time around
794 StgClosure *ioAction; // the io action to run at a breakpoint
795
796 StgAP_STACK *new_aps; // a closure to save the top stack frame on the heap
797 int i;
798 int size_words;
799
800 arg1_brk_array = BCO_NEXT; // 1st arg of break instruction
801 arg2_array_index = BCO_NEXT; // 2nd arg of break instruction
802 arg3_freeVars = BCO_NEXT; // 3rd arg of break instruction
803
804 // check if we are returning from a breakpoint - this info
805 // is stored in the flags field of the current TSO
806 returning_from_break = cap->r.rCurrentTSO->flags & TSO_STOPPED_ON_BREAKPOINT;
807
808 // if we are returning from a break then skip this section
809 // and continue executing
810 if (!returning_from_break)
811 {
812 breakPoints = (StgArrWords *) BCO_PTR(arg1_brk_array);
813
814 // stop the current thread if either the
815 // "rts_stop_next_breakpoint" flag is true OR if the
816 // breakpoint flag for this particular expression is
817 // true
818 if (rts_stop_next_breakpoint == rtsTrue ||
819 breakPoints->payload[arg2_array_index] == rtsTrue)
820 {
821 // make sure we don't automatically stop at the
822 // next breakpoint
823 rts_stop_next_breakpoint = rtsFalse;
824
825 // allocate memory for a new AP_STACK, enough to
826 // store the top stack frame plus an
827 // stg_apply_interp_info pointer and a pointer to
828 // the BCO
829 size_words = BCO_BITMAP_SIZE(obj) + 2;
830 new_aps = (StgAP_STACK *) allocate (AP_STACK_sizeW(size_words));
831 SET_HDR(new_aps,&stg_AP_STACK_info,CCS_SYSTEM);
832 new_aps->size = size_words;
833 new_aps->fun = &stg_dummy_ret_closure;
834
835 // fill in the payload of the AP_STACK
836 new_aps->payload[0] = (StgClosure *)&stg_apply_interp_info;
837 new_aps->payload[1] = (StgClosure *)obj;
838
839 // copy the contents of the top stack frame into the AP_STACK
840 for (i = 2; i < size_words; i++)
841 {
842 new_aps->payload[i] = (StgClosure *)Sp[i-2];
843 }
844
845 // prepare the stack so that we can call the
846 // rts_breakpoint_io_action and ensure that the stack is
847 // in a reasonable state for the GC and so that
848 // execution of this BCO can continue when we resume
849 ioAction = (StgClosure *) deRefStablePtr (rts_breakpoint_io_action);
850 Sp -= 8;
851 Sp[7] = (W_)obj;
852 Sp[6] = (W_)&stg_apply_interp_info;
853 Sp[5] = (W_)new_aps; // the AP_STACK
854 Sp[4] = (W_)BCO_PTR(arg3_freeVars); // the info about local vars of the breakpoint
855 Sp[3] = (W_)False_closure; // True <=> a breakpoint
856 Sp[2] = (W_)&stg_ap_pppv_info;
857 Sp[1] = (W_)ioAction; // apply the IO action to its two arguments above
858 Sp[0] = (W_)&stg_enter_info; // get ready to run the IO action
859
860 // set the flag in the TSO to say that we are now
861 // stopping at a breakpoint so that when we resume
862 // we don't stop on the same breakpoint that we
863 // already stopped at just now
864 cap->r.rCurrentTSO->flags |= TSO_STOPPED_ON_BREAKPOINT;
865
866 // stop this thread and return to the scheduler -
867 // eventually we will come back and the IO action on
868 // the top of the stack will be executed
869 RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding);
870 }
871 }
872 // record that this thread is not stopped at a breakpoint anymore
873 cap->r.rCurrentTSO->flags &= ~TSO_STOPPED_ON_BREAKPOINT;
874
875 // continue normal execution of the byte code instructions
876 goto nextInsn;
877 }
878
879 case bci_STKCHECK: {
880 // Explicit stack check at the beginning of a function
881 // *only* (stack checks in case alternatives are
882 // propagated to the enclosing function).
883 StgWord stk_words_reqd = BCO_GET_LARGE_ARG + 1;
884 if (Sp - stk_words_reqd < SpLim) {
885 Sp -= 2;
886 Sp[1] = (W_)obj;
887 Sp[0] = (W_)&stg_apply_interp_info;
888 RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow);
889 } else {
890 goto nextInsn;
891 }
892 }
893
894 case bci_PUSH_L: {
895 int o1 = BCO_NEXT;
896 Sp[-1] = Sp[o1];
897 Sp--;
898 goto nextInsn;
899 }
900
901 case bci_PUSH_LL: {
902 int o1 = BCO_NEXT;
903 int o2 = BCO_NEXT;
904 Sp[-1] = Sp[o1];
905 Sp[-2] = Sp[o2];
906 Sp -= 2;
907 goto nextInsn;
908 }
909
910 case bci_PUSH_LLL: {
911 int o1 = BCO_NEXT;
912 int o2 = BCO_NEXT;
913 int o3 = BCO_NEXT;
914 Sp[-1] = Sp[o1];
915 Sp[-2] = Sp[o2];
916 Sp[-3] = Sp[o3];
917 Sp -= 3;
918 goto nextInsn;
919 }
920
921 case bci_PUSH_G: {
922 int o1 = BCO_NEXT;
923 Sp[-1] = BCO_PTR(o1);
924 Sp -= 1;
925 goto nextInsn;
926 }
927
928 case bci_PUSH_ALTS: {
929 int o_bco = BCO_NEXT;
930 Sp[-2] = (W_)&stg_ctoi_R1p_info;
931 Sp[-1] = BCO_PTR(o_bco);
932 Sp -= 2;
933 goto nextInsn;
934 }
935
936 case bci_PUSH_ALTS_P: {
937 int o_bco = BCO_NEXT;
938 Sp[-2] = (W_)&stg_ctoi_R1unpt_info;
939 Sp[-1] = BCO_PTR(o_bco);
940 Sp -= 2;
941 goto nextInsn;
942 }
943
944 case bci_PUSH_ALTS_N: {
945 int o_bco = BCO_NEXT;
946 Sp[-2] = (W_)&stg_ctoi_R1n_info;
947 Sp[-1] = BCO_PTR(o_bco);
948 Sp -= 2;
949 goto nextInsn;
950 }
951
952 case bci_PUSH_ALTS_F: {
953 int o_bco = BCO_NEXT;
954 Sp[-2] = (W_)&stg_ctoi_F1_info;
955 Sp[-1] = BCO_PTR(o_bco);
956 Sp -= 2;
957 goto nextInsn;
958 }
959
960 case bci_PUSH_ALTS_D: {
961 int o_bco = BCO_NEXT;
962 Sp[-2] = (W_)&stg_ctoi_D1_info;
963 Sp[-1] = BCO_PTR(o_bco);
964 Sp -= 2;
965 goto nextInsn;
966 }
967
968 case bci_PUSH_ALTS_L: {
969 int o_bco = BCO_NEXT;
970 Sp[-2] = (W_)&stg_ctoi_L1_info;
971 Sp[-1] = BCO_PTR(o_bco);
972 Sp -= 2;
973 goto nextInsn;
974 }
975
976 case bci_PUSH_ALTS_V: {
977 int o_bco = BCO_NEXT;
978 Sp[-2] = (W_)&stg_ctoi_V_info;
979 Sp[-1] = BCO_PTR(o_bco);
980 Sp -= 2;
981 goto nextInsn;
982 }
983
984 case bci_PUSH_APPLY_N:
985 Sp--; Sp[0] = (W_)&stg_ap_n_info;
986 goto nextInsn;
987 case bci_PUSH_APPLY_V:
988 Sp--; Sp[0] = (W_)&stg_ap_v_info;
989 goto nextInsn;
990 case bci_PUSH_APPLY_F:
991 Sp--; Sp[0] = (W_)&stg_ap_f_info;
992 goto nextInsn;
993 case bci_PUSH_APPLY_D:
994 Sp--; Sp[0] = (W_)&stg_ap_d_info;
995 goto nextInsn;
996 case bci_PUSH_APPLY_L:
997 Sp--; Sp[0] = (W_)&stg_ap_l_info;
998 goto nextInsn;
999 case bci_PUSH_APPLY_P:
1000 Sp--; Sp[0] = (W_)&stg_ap_p_info;
1001 goto nextInsn;
1002 case bci_PUSH_APPLY_PP:
1003 Sp--; Sp[0] = (W_)&stg_ap_pp_info;
1004 goto nextInsn;
1005 case bci_PUSH_APPLY_PPP:
1006 Sp--; Sp[0] = (W_)&stg_ap_ppp_info;
1007 goto nextInsn;
1008 case bci_PUSH_APPLY_PPPP:
1009 Sp--; Sp[0] = (W_)&stg_ap_pppp_info;
1010 goto nextInsn;
1011 case bci_PUSH_APPLY_PPPPP:
1012 Sp--; Sp[0] = (W_)&stg_ap_ppppp_info;
1013 goto nextInsn;
1014 case bci_PUSH_APPLY_PPPPPP:
1015 Sp--; Sp[0] = (W_)&stg_ap_pppppp_info;
1016 goto nextInsn;
1017
1018 case bci_PUSH_UBX: {
1019 int i;
1020 int o_lits = BCO_NEXT;
1021 int n_words = BCO_NEXT;
1022 Sp -= n_words;
1023 for (i = 0; i < n_words; i++) {
1024 Sp[i] = (W_)BCO_LIT(o_lits+i);
1025 }
1026 goto nextInsn;
1027 }
1028
1029 case bci_SLIDE: {
1030 int n = BCO_NEXT;
1031 int by = BCO_NEXT;
1032 /* a_1, .. a_n, b_1, .. b_by, s => a_1, .. a_n, s */
1033 while(--n >= 0) {
1034 Sp[n+by] = Sp[n];
1035 }
1036 Sp += by;
1037 INTERP_TICK(it_slides);
1038 goto nextInsn;
1039 }
1040
1041 case bci_ALLOC_AP: {
1042 StgAP* ap;
1043 int n_payload = BCO_NEXT;
1044 ap = (StgAP*)allocate(AP_sizeW(n_payload));
1045 Sp[-1] = (W_)ap;
1046 ap->n_args = n_payload;
1047 SET_HDR(ap, &stg_AP_info, CCS_SYSTEM/*ToDo*/)
1048 Sp --;
1049 goto nextInsn;
1050 }
1051
1052 case bci_ALLOC_PAP: {
1053 StgPAP* pap;
1054 int arity = BCO_NEXT;
1055 int n_payload = BCO_NEXT;
1056 pap = (StgPAP*)allocate(PAP_sizeW(n_payload));
1057 Sp[-1] = (W_)pap;
1058 pap->n_args = n_payload;
1059 pap->arity = arity;
1060 SET_HDR(pap, &stg_PAP_info, CCS_SYSTEM/*ToDo*/)
1061 Sp --;
1062 goto nextInsn;
1063 }
1064
1065 case bci_MKAP: {
1066 int i;
1067 int stkoff = BCO_NEXT;
1068 int n_payload = BCO_NEXT;
1069 StgAP* ap = (StgAP*)Sp[stkoff];
1070 ASSERT((int)ap->n_args == n_payload);
1071 ap->fun = (StgClosure*)Sp[0];
1072
1073 // The function should be a BCO, and its bitmap should
1074 // cover the payload of the AP correctly.
1075 ASSERT(get_itbl(ap->fun)->type == BCO
1076 && BCO_BITMAP_SIZE(ap->fun) == ap->n_args);
1077
1078 for (i = 0; i < n_payload; i++)
1079 ap->payload[i] = (StgClosure*)Sp[i+1];
1080 Sp += n_payload+1;
1081 IF_DEBUG(interpreter,
1082 debugBelch("\tBuilt ");
1083 printObj((StgClosure*)ap);
1084 );
1085 goto nextInsn;
1086 }
1087
1088 case bci_MKPAP: {
1089 int i;
1090 int stkoff = BCO_NEXT;
1091 int n_payload = BCO_NEXT;
1092 StgPAP* pap = (StgPAP*)Sp[stkoff];
1093 ASSERT((int)pap->n_args == n_payload);
1094 pap->fun = (StgClosure*)Sp[0];
1095
1096 // The function should be a BCO
1097 ASSERT(get_itbl(pap->fun)->type == BCO);
1098
1099 for (i = 0; i < n_payload; i++)
1100 pap->payload[i] = (StgClosure*)Sp[i+1];
1101 Sp += n_payload+1;
1102 IF_DEBUG(interpreter,
1103 debugBelch("\tBuilt ");
1104 printObj((StgClosure*)pap);
1105 );
1106 goto nextInsn;
1107 }
1108
1109 case bci_UNPACK: {
1110 /* Unpack N ptr words from t.o.s constructor */
1111 int i;
1112 int n_words = BCO_NEXT;
1113 StgClosure* con = (StgClosure*)Sp[0];
1114 Sp -= n_words;
1115 for (i = 0; i < n_words; i++) {
1116 Sp[i] = (W_)con->payload[i];
1117 }
1118 goto nextInsn;
1119 }
1120
1121 case bci_PACK: {
1122 int i;
1123 int o_itbl = BCO_NEXT;
1124 int n_words = BCO_NEXT;
1125 StgInfoTable* itbl = INFO_PTR_TO_STRUCT(BCO_LIT(o_itbl));
1126 int request = CONSTR_sizeW( itbl->layout.payload.ptrs,
1127 itbl->layout.payload.nptrs );
1128 StgClosure* con = (StgClosure*)allocate_NONUPD(request);
1129 ASSERT( itbl->layout.payload.ptrs + itbl->layout.payload.nptrs > 0);
1130 SET_HDR(con, (StgInfoTable*)BCO_LIT(o_itbl), CCS_SYSTEM/*ToDo*/);
1131 for (i = 0; i < n_words; i++) {
1132 con->payload[i] = (StgClosure*)Sp[i];
1133 }
1134 Sp += n_words;
1135 Sp --;
1136 Sp[0] = (W_)con;
1137 IF_DEBUG(interpreter,
1138 debugBelch("\tBuilt ");
1139 printObj((StgClosure*)con);
1140 );
1141 goto nextInsn;
1142 }
1143
1144 case bci_TESTLT_P: {
1145 unsigned int discr = BCO_NEXT;
1146 int failto = BCO_NEXT;
1147 StgClosure* con = (StgClosure*)Sp[0];
1148 if (GET_TAG(con) >= discr) {
1149 bciPtr = failto;
1150 }
1151 goto nextInsn;
1152 }
1153
1154 case bci_TESTEQ_P: {
1155 unsigned int discr = BCO_NEXT;
1156 int failto = BCO_NEXT;
1157 StgClosure* con = (StgClosure*)Sp[0];
1158 if (GET_TAG(con) != discr) {
1159 bciPtr = failto;
1160 }
1161 goto nextInsn;
1162 }
1163
1164 case bci_TESTLT_I: {
1165 // There should be an Int at Sp[1], and an info table at Sp[0].
1166 int discr = BCO_NEXT;
1167 int failto = BCO_NEXT;
1168 I_ stackInt = (I_)Sp[1];
1169 if (stackInt >= (I_)BCO_LIT(discr))
1170 bciPtr = failto;
1171 goto nextInsn;
1172 }
1173
1174 case bci_TESTEQ_I: {
1175 // There should be an Int at Sp[1], and an info table at Sp[0].
1176 int discr = BCO_NEXT;
1177 int failto = BCO_NEXT;
1178 I_ stackInt = (I_)Sp[1];
1179 if (stackInt != (I_)BCO_LIT(discr)) {
1180 bciPtr = failto;
1181 }
1182 goto nextInsn;
1183 }
1184
1185 case bci_TESTLT_D: {
1186 // There should be a Double at Sp[1], and an info table at Sp[0].
1187 int discr = BCO_NEXT;
1188 int failto = BCO_NEXT;
1189 StgDouble stackDbl, discrDbl;
1190 stackDbl = PK_DBL( & Sp[1] );
1191 discrDbl = PK_DBL( & BCO_LIT(discr) );
1192 if (stackDbl >= discrDbl) {
1193 bciPtr = failto;
1194 }
1195 goto nextInsn;
1196 }
1197
1198 case bci_TESTEQ_D: {
1199 // There should be a Double at Sp[1], and an info table at Sp[0].
1200 int discr = BCO_NEXT;
1201 int failto = BCO_NEXT;
1202 StgDouble stackDbl, discrDbl;
1203 stackDbl = PK_DBL( & Sp[1] );
1204 discrDbl = PK_DBL( & BCO_LIT(discr) );
1205 if (stackDbl != discrDbl) {
1206 bciPtr = failto;
1207 }
1208 goto nextInsn;
1209 }
1210
1211 case bci_TESTLT_F: {
1212 // There should be a Float at Sp[1], and an info table at Sp[0].
1213 int discr = BCO_NEXT;
1214 int failto = BCO_NEXT;
1215 StgFloat stackFlt, discrFlt;
1216 stackFlt = PK_FLT( & Sp[1] );
1217 discrFlt = PK_FLT( & BCO_LIT(discr) );
1218 if (stackFlt >= discrFlt) {
1219 bciPtr = failto;
1220 }
1221 goto nextInsn;
1222 }
1223
1224 case bci_TESTEQ_F: {
1225 // There should be a Float at Sp[1], and an info table at Sp[0].
1226 int discr = BCO_NEXT;
1227 int failto = BCO_NEXT;
1228 StgFloat stackFlt, discrFlt;
1229 stackFlt = PK_FLT( & Sp[1] );
1230 discrFlt = PK_FLT( & BCO_LIT(discr) );
1231 if (stackFlt != discrFlt) {
1232 bciPtr = failto;
1233 }
1234 goto nextInsn;
1235 }
1236
1237 // Control-flow ish things
1238 case bci_ENTER:
1239 // Context-switch check. We put it here to ensure that
1240 // the interpreter has done at least *some* work before
1241 // context switching: sometimes the scheduler can invoke
1242 // the interpreter with context_switch == 1, particularly
1243 // if the -C0 flag has been given on the cmd line.
1244 if (context_switch) {
1245 Sp--; Sp[0] = (W_)&stg_enter_info;
1246 RETURN_TO_SCHEDULER(ThreadInterpret, ThreadYielding);
1247 }
1248 goto eval;
1249
1250 case bci_RETURN:
1251 obj = (StgClosure *)Sp[0];
1252 Sp++;
1253 goto do_return;
1254
1255 case bci_RETURN_P:
1256 Sp--;
1257 Sp[0] = (W_)&stg_gc_unpt_r1_info;
1258 goto do_return_unboxed;
1259 case bci_RETURN_N:
1260 Sp--;
1261 Sp[0] = (W_)&stg_gc_unbx_r1_info;
1262 goto do_return_unboxed;
1263 case bci_RETURN_F:
1264 Sp--;
1265 Sp[0] = (W_)&stg_gc_f1_info;
1266 goto do_return_unboxed;
1267 case bci_RETURN_D:
1268 Sp--;
1269 Sp[0] = (W_)&stg_gc_d1_info;
1270 goto do_return_unboxed;
1271 case bci_RETURN_L:
1272 Sp--;
1273 Sp[0] = (W_)&stg_gc_l1_info;
1274 goto do_return_unboxed;
1275 case bci_RETURN_V:
1276 Sp--;
1277 Sp[0] = (W_)&stg_gc_void_info;
1278 goto do_return_unboxed;
1279
1280 case bci_SWIZZLE: {
1281 int stkoff = BCO_NEXT;
1282 signed short n = (signed short)(BCO_NEXT);
1283 Sp[stkoff] += (W_)n;
1284 goto nextInsn;
1285 }
1286
1287 case bci_CCALL: {
1288 void *tok;
1289 int stk_offset = BCO_NEXT;
1290 int o_itbl = BCO_NEXT;
1291 void(*marshall_fn)(void*) = (void (*)(void*))BCO_LIT(o_itbl);
1292 int ret_dyn_size =
1293 RET_DYN_BITMAP_SIZE + RET_DYN_NONPTR_REGS_SIZE
1294 + sizeofW(StgRetDyn);
1295
1296 #ifdef THREADED_RTS
1297 // Threaded RTS:
1298 // Arguments on the TSO stack are not good, because garbage
1299 // collection might move the TSO as soon as we call
1300 // suspendThread below.
1301
1302 W_ arguments[stk_offset];
1303
1304 memcpy(arguments, Sp, sizeof(W_) * stk_offset);
1305 #endif
1306
1307 // Restore the Haskell thread's current value of errno
1308 errno = cap->r.rCurrentTSO->saved_errno;
1309
1310 // There are a bunch of non-ptr words on the stack (the
1311 // ccall args, the ccall fun address and space for the
1312 // result), which we need to cover with an info table
1313 // since we might GC during this call.
1314 //
1315 // We know how many (non-ptr) words there are before the
1316 // next valid stack frame: it is the stk_offset arg to the
1317 // CCALL instruction. So we build a RET_DYN stack frame
1318 // on the stack frame to describe this chunk of stack.
1319 //
1320 Sp -= ret_dyn_size;
1321 ((StgRetDyn *)Sp)->liveness = NO_PTRS | N_NONPTRS(stk_offset);
1322 ((StgRetDyn *)Sp)->info = (StgInfoTable *)&stg_gc_gen_info;
1323
1324 SAVE_STACK_POINTERS;
1325 tok = suspendThread(&cap->r);
1326
1327 #ifndef THREADED_RTS
1328 // Careful:
1329 // suspendThread might have shifted the stack
1330 // around (stack squeezing), so we have to grab the real
1331 // Sp out of the TSO to find the ccall args again.
1332
1333 marshall_fn ( (void*)(cap->r.rCurrentTSO->sp + ret_dyn_size) );
1334 #else
1335 // Threaded RTS:
1336 // We already made a copy of the arguments above.
1337
1338 marshall_fn ( arguments );
1339 #endif
1340
1341 // And restart the thread again, popping the RET_DYN frame.
1342 cap = (Capability *)((void *)((unsigned char*)resumeThread(tok) - sizeof(StgFunTable)));
1343 LOAD_STACK_POINTERS;
1344 Sp += ret_dyn_size;
1345
1346 // Save the Haskell thread's current value of errno
1347 cap->r.rCurrentTSO->saved_errno = errno;
1348
1349 #ifdef THREADED_RTS
1350 // Threaded RTS:
1351 // Copy the "arguments", which might include a return value,
1352 // back to the TSO stack. It would of course be enough to
1353 // just copy the return value, but we don't know the offset.
1354 memcpy(Sp, arguments, sizeof(W_) * stk_offset);
1355 #endif
1356
1357 goto nextInsn;
1358 }
1359
1360 case bci_JMP: {
1361 /* BCO_NEXT modifies bciPtr, so be conservative. */
1362 int nextpc = BCO_NEXT;
1363 bciPtr = nextpc;
1364 goto nextInsn;
1365 }
1366
1367 case bci_CASEFAIL:
1368 barf("interpretBCO: hit a CASEFAIL");
1369
1370 // Errors
1371 default:
1372 barf("interpretBCO: unknown or unimplemented opcode %d",
1373 (int)BCO_NEXT);
1374
1375 } /* switch on opcode */
1376 }
1377 }
1378
1379 barf("interpretBCO: fell off end of the interpreter");
1380 }