rts-heap.c
1 //! @file rts-heap.c
2 //! @author J. Marcel van der Veer
3
4 //! @section Copyright
5 //!
6 //! This file is part of Algol68G - an Algol 68 compiler-interpreter.
7 //! Copyright 2001-2024 J. Marcel van der Veer [algol68g@xs4all.nl].
8
9 //! @section License
10 //!
11 //! This program is free software; you can redistribute it and/or modify it
12 //! under the terms of the GNU General Public License as published by the
13 //! Free Software Foundation; either version 3 of the License, or
14 //! (at your option) any later version.
15 //!
16 //! This program is distributed in the hope that it will be useful, but
17 //! WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
18 //! or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
19 //! more details. You should have received a copy of the GNU General Public
20 //! License along with this program. If not, see [http://www.gnu.org/licenses/].
21
22 //! @section Synopsis
23 //!
24 //! Generator and garbage collector routines.
25
26 // The generator allocates space in stack or heap and initialises dynamically sized objects.
27 //
28 // A mark-and-gc garbage collector defragments the heap. When called, it walks
29 // the stack frames and marks the heap space that is still active. This marking
30 // process is called "colouring" here since we "pour paint" into the heap.
31 // The active blocks are then joined, the non-active blocks are forgotten.
32 //
33 // When colouring the heap, "cookies" are placed in objects as to find circular
34 // references.
35 //
36 // Algol68G introduces several anonymous tags in the symbol tables that save
37 // temporary REF or ROW results, so that they do not get prematurely swept.
38 //
39 // The genie is not smart enough to handle every heap clog, e.g. when copying
40 // STOWED objects. This seems not very elegant, but garbage collectors in general
41 // cannot solve all core management problems. To avoid many of the "unforeseen"
42 // heap clogs, we try to keep heap occupation low by garbage collecting
43 // occasionally, before it fills up completely. If this automatic mechanism does
44 // not help, one can always invoke the garbage collector by calling "gc heap"
45 // from Algol 68 source text.
46 //
47 // Mark-and-collect is simple but since it walks recursive structures, it could
48 // exhaust the C-stack (segment violation). A rough check is in place.
49 //
50 // For dynamically sized objects, first bounds are evaluated (right first, then down).
51 // The object is generated keeping track of the bound-count.
52 //
53 // ...
54 // [#1]
55 // STRUCT
56 // (
57 // [#2]
58 // STRUCT
59 // (
60 // [#3] A a, b, ...
61 // )
62 // , Advance bound-count here, max is #3
63 // [#4] B a, b, ...
64 // )
65 // , Advance bound-count here, max is #4
66 // [#5] C a, b, ...
67 // ...
68 //
69 // Bound-count is maximised when generator_stowed is entered recursively.
70 // Bound-count is advanced when completing a STRUCTURED_FIELD.
71 // Note that A68G will not extend stack frames. Thus only 'static' LOC generators
72 // are in the stack, and 'dynamic' LOC generators go into the heap. These local
73 // REFs in the heap get local scope however, and A68G's approach differs from the
74 // CDC ALGOL 68 approach that put all generators in the heap.
75 // Note that part of memory is called 'COMMON'. This is meant for future extension
76 // where a68g would need to point to external objects. The adressing scheme is that
77 // of a HEAP pointer - handle pointer + offset.
78
79 #include "a68g.h"
80 #include "a68g-genie.h"
81 #include "a68g-frames.h"
82 #include "a68g-prelude.h"
83 #include "a68g-parser.h"
84
85 #define DEF_NODE(p) (NEXT_NEXT (NODE (TAX (p))))
86
87 //! @brief PROC VOID gc heap
88
89 void genie_gc_heap (NODE_T * p)
90 {
91 gc_heap (p, A68_FP);
92 }
93
94 //! @brief PROC VOID preemptive gc heap
95
96 void genie_preemptive_gc_heap (NODE_T * p)
97 {
98 if (A68_GC (preemptive)) {
99 gc_heap (p, A68_FP);
100 }
101 }
102
103 //! @brief INT blocks
104
105 void genie_block (NODE_T * p)
106 {
107 PUSH_VALUE (p, 0, A68_INT);
108 }
109
110 //! @brief INT garbage collections
111
112 void genie_garbage_collections (NODE_T * p)
113 {
114 PUSH_VALUE (p, A68_GC (sweeps), A68_INT);
115 }
116
117 //! @brief INT garbage refused
118
119 void genie_garbage_refused (NODE_T * p)
120 {
121 PUSH_VALUE (p, A68_GC (refused), A68_INT);
122 }
123
124 //! @brief LONG INT garbage freed
125
126 void genie_garbage_freed (NODE_T * p)
127 {
128 PUSH_VALUE (p, A68_GC (total), A68_INT);
129 }
130
131 //! @brief REAL garbage seconds
132
133 void genie_garbage_seconds (NODE_T * p)
134 {
135 // Note that this timing is a rough cut.
136 PUSH_VALUE (p, A68_GC (seconds), A68_REAL);
137 }
138
139 //! @brief Size available for an object in the heap.
140
141 unt heap_available (void)
142 {
143 return A68 (heap_size) - A68_HP;
144 }
145
146 //! @brief Initialise heap management.
147
148 void genie_init_heap (NODE_T * p)
149 {
150 (void) p;
151 if (A68_HEAP == NO_BYTE) {
152 diagnostic (A68_RUNTIME_ERROR, TOP_NODE (&A68_JOB), ERROR_OUT_OF_CORE);
153 exit_genie (TOP_NODE (&A68_JOB), A68_RUNTIME_ERROR);
154 }
155 if (A68_HANDLES == NO_BYTE) {
156 diagnostic (A68_RUNTIME_ERROR, TOP_NODE (&A68_JOB), ERROR_OUT_OF_CORE);
157 exit_genie (TOP_NODE (&A68_JOB), A68_RUNTIME_ERROR);
158 }
159 A68_GC (seconds) = 0;
160 A68_GC (total) = 0;
161 A68_GC (sweeps) = 0;
162 A68_GC (refused) = 0;
163 A68_GC (preemptive) = A68_FALSE;
164 ABEND (A68 (fixed_heap_pointer) >= (A68 (heap_size) - MIN_MEM_SIZE), ERROR_OUT_OF_CORE, __func__);
165 A68_HP = A68 (fixed_heap_pointer);
166 A68 (heap_is_fluid) = A68_FALSE;
167 // Assign handle space.
168 A68_HANDLE *z = (A68_HANDLE *) A68_HANDLES;
169 A68_GC (available_handles) = z;
170 A68_GC (busy_handles) = NO_HANDLE;
171 int N = (unt) A68 (handle_pool_size) / SIZE_ALIGNED (A68_HANDLE);
172 A68_GC (free_handles) = N;
173 A68_GC (max_handles) = N;
174 for (int k = 0; k < N; k++) {
175 STATUS (&(z[k])) = NULL_MASK;
176 POINTER (&(z[k])) = NO_BYTE;
177 SIZE (&(z[k])) = 0;
178 NEXT (&z[k]) = (k == N - 1 ? NO_HANDLE : &z[k + 1]);
179 PREVIOUS (&z[k]) = (k == 0 ? NO_HANDLE : &z[k - 1]);
180 }
181 }
182
183 //! @brief Whether mode must be coloured.
184
185 BOOL_T moid_needs_colouring (MOID_T * m)
186 {
187 if (IS_REF (m)) {
188 return A68_TRUE;
189 } else if (IS (m, PROC_SYMBOL)) {
190 return A68_TRUE;
191 } else if (IS_FLEX (m) || IS_ROW (m)) {
192 return A68_TRUE;
193 } else if (IS_STRUCT (m) || IS_UNION (m)) {
194 for (PACK_T *p = PACK (m); p != NO_PACK; FORWARD (p)) {
195 if (moid_needs_colouring (MOID (p))) {
196 return A68_TRUE;
197 }
198 }
199 return A68_FALSE;
200 } else {
201 return A68_FALSE;
202 }
203 }
204
205 //! @brief Colour all elements of a row.
206
207 void colour_row_elements (A68_REF * z, MOID_T * m)
208 {
209 A68_ARRAY *arr; A68_TUPLE *tup;
210 GET_DESCRIPTOR (arr, tup, z);
211 if (get_row_size (tup, DIM (arr)) == 0) {
212 // Empty rows have a ghost elements.
213 BYTE_T *elem = ADDRESS (&ARRAY (arr));
214 colour_object (&elem[0], SUB (m));
215 } else {
216 // The multi-dimensional garbage collector.
217 BYTE_T *elem = ADDRESS (&ARRAY (arr));
218 BOOL_T done = A68_FALSE;
219 initialise_internal_index (tup, DIM (arr));
220 while (!done) {
221 ADDR_T index = calculate_internal_index (tup, DIM (arr));
222 ADDR_T addr = ROW_ELEMENT (arr, index);
223 colour_object (&elem[addr], SUB (m));
224 done = increment_internal_index (tup, DIM (arr));
225 }
226 }
227 }
228
229 //! @brief Colour an (active) object.
230
231 void colour_object (BYTE_T * item, MOID_T * m)
232 {
233 if (item == NO_BYTE || m == NO_MOID) {
234 return;
235 }
236 if (!moid_needs_colouring (m)) {
237 return;
238 }
239 // Deeply recursive objects might exhaust the stack.
240 LOW_STACK_ALERT (NO_NODE);
241 if (IS_REF (m)) {
242 // REF AMODE colour pointer and object to which it refers.
243 A68_REF *z = (A68_REF *) item;
244 if (INITIALISED (z) && IS_IN_HEAP (z)) {
245 if (STATUS_TEST (REF_HANDLE (z), COOKIE_MASK)) {
246 return;
247 }
248 STATUS_SET (REF_HANDLE (z), (COOKIE_MASK | COLOUR_MASK));
249 if (!IS_NIL (*z)) {
250 colour_object (ADDRESS (z), SUB (m));
251 }
252 // STATUS_CLEAR (REF_HANDLE (z), COOKIE_MASK);.
253 }
254 } else if (IS_FLEXETY_ROW (m)) {
255 // Claim the descriptor and the row itself.
256 A68_REF *z = (A68_REF *) item;
257 if (INITIALISED (z) && IS_IN_HEAP (z)) {
258 if (STATUS_TEST (REF_HANDLE (z), COOKIE_MASK)) {
259 return;
260 }
261 // An array is ALWAYS in the heap.
262 STATUS_SET (REF_HANDLE (z), (COOKIE_MASK | COLOUR_MASK));
263 A68_ARRAY *arr; A68_TUPLE *tup;
264 GET_DESCRIPTOR (arr, tup, z);
265 if (REF_HANDLE (&(ARRAY (arr))) != NO_HANDLE) {
266 // Assume its initialisation.
267 MOID_T *n = DEFLEX (m);
268 STATUS_SET (REF_HANDLE (&(ARRAY (arr))), COLOUR_MASK);
269 if (moid_needs_colouring (SUB (n))) {
270 colour_row_elements (z, n);
271 }
272 }
273 // STATUS_CLEAR (REF_HANDLE (z), COOKIE_MASK);.
274 (void) tup;
275 }
276 } else if (IS_STRUCT (m)) {
277 // STRUCTures - colour fields.
278 for (PACK_T *p = PACK (m); p != NO_PACK; FORWARD (p)) {
279 colour_object (&item[OFFSET (p)], MOID (p));
280 }
281 } else if (IS_UNION (m)) {
282 // UNIONs - a united object may contain a value that needs colouring.
283 A68_UNION *z = (A68_UNION *) item;
284 if (INITIALISED (z)) {
285 MOID_T *united_moid = (MOID_T *) VALUE (z);
286 colour_object (&item[A68_UNION_SIZE], united_moid);
287 }
288 } else if (IS (m, PROC_SYMBOL)) {
289 // PROCs - save a locale and the objects it points to.
290 A68_PROCEDURE *z = (A68_PROCEDURE *) item;
291 if (INITIALISED (z) && LOCALE (z) != NO_HANDLE && !(STATUS_TEST (LOCALE (z), COOKIE_MASK))) {
292 BYTE_T *u = POINTER (LOCALE (z));
293 STATUS_SET (LOCALE (z), (COOKIE_MASK | COLOUR_MASK));
294 for (PACK_T *s = PACK (MOID (z)); s != NO_PACK; FORWARD (s)) {
295 if (VALUE ((A68_BOOL *) & u[0]) == A68_TRUE) {
296 colour_object (&u[SIZE (M_BOOL)], MOID (s));
297 }
298 u = &(u[SIZE (M_BOOL) + SIZE (MOID (s))]);
299 }
300 // STATUS_CLEAR (LOCALE (z), COOKIE_MASK);.
301 }
302 } else if (m == M_SOUND) {
303 // Claim the data of a SOUND object, that is in the heap.
304 A68_SOUND *w = (A68_SOUND *) item;
305 if (INITIALISED (w)) {
306 STATUS_SET (REF_HANDLE (&(DATA (w))), (COOKIE_MASK | COLOUR_MASK));
307 }
308 }
309 }
310
311 //! @brief Colour active objects in the heap.
312
313 void colour_heap (ADDR_T fp)
314 {
315 while (fp != 0) {
316 NODE_T *p = FRAME_TREE (fp);
317 TABLE_T *q = TABLE (p);
318 if (q != NO_TABLE) {
319 for (TAG_T *i = IDENTIFIERS (q); i != NO_TAG; FORWARD (i)) {
320 colour_object (FRAME_LOCAL (fp, OFFSET (i)), MOID (i));
321 }
322 for (TAG_T *i = ANONYMOUS (q); i != NO_TAG; FORWARD (i)) {
323 if (PRIO (i) == GENERATOR) {
324 colour_object (FRAME_LOCAL (fp, OFFSET (i)), MOID (i));
325 }
326 }
327 }
328 fp = FRAME_DYNAMIC_LINK (fp);
329 }
330 }
331
332 //! @brief Join all active blocks in the heap.
333
334 void defragment_heap (void)
335 {
336 A68_HANDLE *z;
337 // Free handles.
338 z = A68_GC (busy_handles);
339 while (z != NO_HANDLE) {
340 if (!(STATUS_TEST (z, COLOUR_MASK)) && !(STATUS_TEST (z, BLOCK_GC_MASK))) {
341 A68_HANDLE *y = NEXT (z);
342 if (PREVIOUS (z) == NO_HANDLE) {
343 A68_GC (busy_handles) = NEXT (z);
344 } else {
345 NEXT (PREVIOUS (z)) = NEXT (z);
346 }
347 if (NEXT (z) != NO_HANDLE) {
348 PREVIOUS (NEXT (z)) = PREVIOUS (z);
349 }
350 NEXT (z) = A68_GC (available_handles);
351 PREVIOUS (z) = NO_HANDLE;
352 if (NEXT (z) != NO_HANDLE) {
353 PREVIOUS (NEXT (z)) = z;
354 }
355 A68_GC (available_handles) = z;
356 STATUS_CLEAR (z, ALLOCATED_MASK);
357 A68_GC (freed) += SIZE (z);
358 A68_GC (free_handles)++;
359 z = y;
360 } else {
361 FORWARD (z);
362 }
363 }
364 // There can be no uncoloured allocated handle.
365 for (z = A68_GC (busy_handles); z != NO_HANDLE; FORWARD (z)) {
366 ABEND (!(STATUS_TEST (z, COLOUR_MASK)) && !(STATUS_TEST (z, BLOCK_GC_MASK)), ERROR_INTERNAL_CONSISTENCY, __func__);
367 }
368 // Defragment the heap.
369 A68_HP = A68 (fixed_heap_pointer);
370 for (z = A68_GC (busy_handles); z != NO_HANDLE && NEXT (z) != NO_HANDLE; FORWARD (z)) {
371 ;
372 }
373 for (; z != NO_HANDLE; BACKWARD (z)) {
374 BYTE_T *dst = HEAP_ADDRESS (A68_HP);
375 if (dst != POINTER (z)) {
376 MOVE (dst, POINTER (z), (unt) SIZE (z));
377 }
378 STATUS_CLEAR (z, (COLOUR_MASK | COOKIE_MASK));
379 POINTER (z) = dst;
380 A68_HP += (SIZE (z));
381 ABEND (A68_HP % A68_ALIGNMENT != 0, ERROR_ALIGNMENT, __func__);
382 }
383 }
384
385 //! @brief Clean up garbage and defragment the heap.
386
387 void gc_heap (NODE_T * p, ADDR_T fp)
388 {
389 // Must start with fp = current frame_pointer.
390 A68_HANDLE *z;
391 REAL_T t0, t1;
392 #if defined (BUILD_PARALLEL_CLAUSE)
393 if (OTHER_THREAD (FRAME_THREAD_ID (A68_FP), A68_PAR (main_thread_id))) {
394 A68_GC (refused)++;
395 return;
396 }
397 #endif
398 if (STATUS_TEST (p, BLOCK_GC_MASK) || A68_GC (sema) > 0) {
399 A68_GC (refused)++;
400 return;
401 }
402 // Take no risk when intermediate results are on the stack.
403 if (A68_SP != A68 (stack_start)) {
404 A68_GC (refused)++;
405 return;
406 }
407 // Give it a whirl then.
408 t0 = seconds ();
409 // Unfree handles are subject to inspection.
410 // Release them all before colouring.
411 for (z = A68_GC (busy_handles); z != NO_HANDLE; FORWARD (z)) {
412 STATUS_CLEAR (z, (COLOUR_MASK | COOKIE_MASK));
413 }
414 // Pour paint into the heap to reveal active objects.
415 colour_heap (fp);
416 // Start freeing and compacting.
417 A68_GC (freed) = 0;
418 defragment_heap ();
419 // Stats and logging.
420 A68_GC (total) += A68_GC (freed);
421 A68_GC (sweeps)++;
422 A68_GC (preemptive) = A68_FALSE;
423 t1 = seconds ();
424 // C optimiser can make last digit differ, so next condition is
425 // needed to determine a positive time difference
426 if ((t1 - t0) > ((REAL_T) A68 (clock_res) / 2.0)) {
427 A68_GC (seconds) += (t1 - t0);
428 } else {
429 A68_GC (seconds) += ((REAL_T) A68 (clock_res) / 2.0);
430 }
431 // Call the event handler.
432 genie_call_event_routine (p, M_PROC_VOID, &A68 (on_gc_event), A68_SP, A68_FP);
433 }
434
435 //! @brief Yield a handle that will point to a block in the heap.
436
437 A68_HANDLE *give_handle (NODE_T * p, MOID_T * a68m)
438 {
439 if (A68_GC (available_handles) != NO_HANDLE) {
440 A68_HANDLE *x = A68_GC (available_handles);
441 A68_GC (available_handles) = NEXT (x);
442 if (A68_GC (available_handles) != NO_HANDLE) {
443 PREVIOUS (A68_GC (available_handles)) = NO_HANDLE;
444 }
445 STATUS (x) = ALLOCATED_MASK;
446 POINTER (x) = NO_BYTE;
447 SIZE (x) = 0;
448 MOID (x) = a68m;
449 NEXT (x) = A68_GC (busy_handles);
450 PREVIOUS (x) = NO_HANDLE;
451 if (NEXT (x) != NO_HANDLE) {
452 PREVIOUS (NEXT (x)) = x;
453 }
454 A68_GC (busy_handles) = x;
455 A68_GC (free_handles)--;
456 return x;
457 } else {
458 // Do not auto-GC!.
459 diagnostic (A68_RUNTIME_ERROR, p, ERROR_OUT_OF_CORE);
460 exit_genie (p, A68_RUNTIME_ERROR);
461 }
462 return NO_HANDLE;
463 }
464
465 //! @brief Give a block of heap for an object of indicated mode.
466
467 A68_REF heap_generator (NODE_T * p, MOID_T * mode, int size)
468 {
469 ABEND (size < 0, ERROR_INVALID_SIZE, __func__);
470 size = A68_ALIGN (size);
471 if (heap_available () >= size) {
472 A68_REF z;
473 STATUS (&z) = (STATUS_MASK_T) (INIT_MASK | IN_HEAP_MASK);
474 OFFSET (&z) = 0;
475 A68_HANDLE *x = give_handle (p, mode);
476 SIZE (x) = size;
477 POINTER (x) = HEAP_ADDRESS (A68_HP);
478 FILL (POINTER (x), 0, size);
479 REF_SCOPE (&z) = PRIMAL_SCOPE;
480 REF_HANDLE (&z) = x;
481 ABEND (((long) ADDRESS (&z)) % A68_ALIGNMENT != 0, ERROR_ALIGNMENT, __func__);
482 A68_HP += size;
483 REAL_T _f_ = (REAL_T) A68_HP / (REAL_T) A68 (heap_size);
484 REAL_T _g_ = (REAL_T) (A68_GC (max_handles) - A68_GC (free_handles)) / (REAL_T) A68_GC (max_handles);
485 if (_f_ > DEFAULT_PREEMPTIVE || _g_ > DEFAULT_PREEMPTIVE) {
486 A68_GC (preemptive) = A68_TRUE;
487 }
488 return z;
489 } else {
490 // Do not auto-GC!.
491 diagnostic (A68_RUNTIME_ERROR, p, ERROR_OUT_OF_CORE);
492 exit_genie (p, A68_RUNTIME_ERROR);
493 return nil_ref;
494 }
495 }
496
497 //! @brief Give a block of heap for an object of indicated mode.
498
499 A68_REF heap_generator_2 (NODE_T * p, MOID_T * mode, int len, int size)
500 {
501 if (len == 0 || size == 0) {
502 return heap_generator (p, mode, 0);
503 } else if (ABS (size) < (2 * GIGABYTE) / ABS (len)) {
504 return heap_generator (p, mode, len * size);
505 } else {
506 diagnostic (A68_RUNTIME_ERROR, p, ERROR_OUT_OF_CORE);
507 exit_genie (p, A68_RUNTIME_ERROR);
508 }
509 return nil_ref;
510 }
511
512 //! @brief Give a block of heap for an object of indicated mode.
513
514 A68_REF heap_generator_3 (NODE_T * p, MOID_T * mode, int len1, int len2, int size)
515 {
516 if (len1 == 0 || len2 == 0) {
517 return heap_generator (p, mode, 0);
518 } else if (ABS (len2) < (2 * GIGABYTE) / ABS (len1)) {
519 return heap_generator_2 (p, mode, len1 * len2, size);
520 } else {
521 diagnostic (A68_RUNTIME_ERROR, p, ERROR_OUT_OF_CORE);
522 exit_genie (p, A68_RUNTIME_ERROR);
523 }
524 return nil_ref;
525 }
526
527 // Following implements the generator.
528
529 //! @brief Whether a moid needs work in allocation.
530
531 BOOL_T mode_needs_allocation (MOID_T * m)
532 {
533 if (IS_UNION (m)) {
534 return A68_FALSE;
535 } else {
536 return HAS_ROWS (m);
537 }
538 }
539
540 //! @brief Prepare bounds.
541
542 void genie_compute_bounds (NODE_T * p)
543 {
544 for (; p != NO_NODE; FORWARD (p)) {
545 if (IS (p, BOUNDS_LIST)) {
546 genie_compute_bounds (SUB (p));
547 } else if (IS (p, BOUND)) {
548 genie_compute_bounds (SUB (p));
549 } else if (IS (p, UNIT)) {
550 if (NEXT (p) != NO_NODE && (is_one_of (NEXT (p), COLON_SYMBOL, DOTDOT_SYMBOL, STOP))) {
551 GENIE_UNIT (p);
552 p = NEXT_NEXT (p);
553 } else {
554 // Default lower bound.
555 PUSH_VALUE (p, 1, A68_INT);
556 }
557 GENIE_UNIT (p);
558 }
559 }
560 }
561
562 //! @brief Prepare bounds for a row.
563
564 void genie_generator_bounds (NODE_T * p)
565 {
566 LOW_STACK_ALERT (p);
567 for (; p != NO_NODE; FORWARD (p)) {
568 if (IS (p, BOUNDS)) {
569 genie_compute_bounds (SUB (p));
570 } else if (IS (p, INDICANT) && IS_LITERALLY (p, "STRING")) {
571 return;
572 } else if (IS (p, INDICANT)) {
573 if (TAX (p) != NO_TAG && HAS_ROWS (MOID (TAX (p)))) {
574 // Continue from definition at MODE A = ....
575 genie_generator_bounds (DEF_NODE (p));
576 }
577 } else if (IS (p, DECLARER) && !mode_needs_allocation (MOID (p))) {
578 return;
579 } else {
580 genie_generator_bounds (SUB (p));
581 }
582 }
583 }
584
585 //! @brief Allocate a structure.
586
587 void genie_generator_field (NODE_T * p, BYTE_T ** faddr, NODE_T ** decl, ADDR_T * cur_sp, ADDR_T * top_sp)
588 {
589 for (; p != NO_NODE; FORWARD (p)) {
590 if (IS (p, STRUCTURED_FIELD)) {
591 genie_generator_field (SUB (p), faddr, decl, cur_sp, top_sp);
592 }
593 if (IS (p, DECLARER)) {
594 (*decl) = SUB (p);
595 FORWARD (p);
596 }
597 if (IS (p, FIELD_IDENTIFIER)) {
598 MOID_T *fmoid = MOID (*decl);
599 if (HAS_ROWS (fmoid) && ISNT (fmoid, UNION_SYMBOL)) {
600 ADDR_T pop_sp = *cur_sp;
601 genie_generator_stowed (*decl, *faddr, NO_VAR, cur_sp);
602 *top_sp = *cur_sp;
603 *cur_sp = pop_sp;
604 }
605 (*faddr) += SIZE (fmoid);
606 }
607 }
608 }
609
610 //! @brief Allocate a structure.
611
612 void genie_generator_struct (NODE_T * p, BYTE_T ** faddr, ADDR_T * cur_sp)
613 {
614 for (; p != NO_NODE; FORWARD (p)) {
615 if (IS (p, STRUCTURED_FIELD_LIST)) {
616 genie_generator_struct (SUB (p), faddr, cur_sp);
617 } else if (IS (p, STRUCTURED_FIELD)) {
618 NODE_T *decl = NO_NODE;
619 ADDR_T top_sp = *cur_sp;
620 genie_generator_field (SUB (p), faddr, &decl, cur_sp, &top_sp);
621 *cur_sp = top_sp;
622 }
623 }
624 }
625
626 //! @brief Allocate a stowed object.
627
628 void genie_generator_stowed (NODE_T * p, BYTE_T * addr, NODE_T ** decl, ADDR_T * cur_sp)
629 {
630 if (p == NO_NODE) {
631 return;
632 } else if (IS (p, INDICANT) && IS_LITERALLY (p, "STRING")) {
633 // The standard prelude definition is hard coded here.
634 *((A68_REF *) addr) = empty_string (p);
635 return;
636 } else if (IS (p, INDICANT) && TAX (p) != NO_TAG) {
637 // Continue from definition at MODE A = ..
638 genie_generator_stowed (DEF_NODE (p), addr, decl, cur_sp);
639 return;
640 } else if (IS (p, DECLARER) && mode_needs_allocation (MOID (p))) {
641 genie_generator_stowed (SUB (p), addr, decl, cur_sp);
642 return;
643 } else if (IS_STRUCT (p)) {
644 BYTE_T *faddr = addr;
645 genie_generator_struct (SUB_NEXT (p), &faddr, cur_sp);
646 return;
647 } else if (IS_FLEX (p)) {
648 genie_generator_stowed (NEXT (p), addr, decl, cur_sp);
649 return;
650 } else if (IS (p, BOUNDS)) {
651 A68_REF desc;
652 MOID_T *rmod = MOID (p), *smod = MOID (NEXT (p));
653 BYTE_T *bounds = STACK_ADDRESS (*cur_sp);
654 int dim = DIM (DEFLEX (rmod)), esiz = SIZE (smod), rsiz = 1;
655 BOOL_T alloc_sub = A68_FALSE, alloc_str = A68_FALSE;
656 NODE_T *in = SUB_NEXT (p);
657 if (IS (in, INDICANT) && IS_LITERALLY (in, "STRING")) {
658 alloc_str = A68_TRUE;
659 alloc_sub = A68_FALSE;
660 } else {
661 alloc_sub = mode_needs_allocation (smod);
662 alloc_str = A68_FALSE;
663 }
664 desc = heap_generator (p, rmod, DESCRIPTOR_SIZE (dim));
665 A68_ARRAY *arr; A68_TUPLE *tup;
666 GET_DESCRIPTOR (arr, tup, &desc);
667 for (int k = 0; k < dim; k++) {
668 CHECK_INIT (p, INITIALISED ((A68_INT *) bounds), M_INT);
669 LWB (&tup[k]) = VALUE ((A68_INT *) bounds);
670 bounds += SIZE (M_INT);
671 CHECK_INIT (p, INITIALISED ((A68_INT *) bounds), M_INT);
672 UPB (&tup[k]) = VALUE ((A68_INT *) bounds);
673 bounds += SIZE (M_INT);
674 SPAN (&tup[k]) = rsiz;
675 SHIFT (&tup[k]) = LWB (&tup[k]) * SPAN (&tup[k]);
676 rsiz *= ROW_SIZE (&tup[k]);
677 }
678 DIM (arr) = dim;
679 MOID (arr) = smod;
680 ELEM_SIZE (arr) = esiz;
681 SLICE_OFFSET (arr) = 0;
682 FIELD_OFFSET (arr) = 0;
683 (*cur_sp) += (dim * 2 * SIZE (M_INT));
684 // Generate a new row. Note that STRING is handled explicitly since
685 // it has implicit bounds
686 if (rsiz == 0) {
687 // Generate a ghost element.
688 ADDR_T top_sp = *cur_sp;
689 ARRAY (arr) = heap_generator (p, rmod, esiz);
690 BYTE_T *elem = ADDRESS (&(ARRAY (arr)));
691 if (alloc_sub) {
692 genie_generator_stowed (NEXT (p), &(elem[0]), NO_VAR, cur_sp);
693 top_sp = *cur_sp;
694 } else if (alloc_str) {
695 *(A68_REF *) elem = empty_string (p);
696 }
697 (*cur_sp) = top_sp;
698 } else {
699 ADDR_T pop_sp = *cur_sp, top_sp = *cur_sp;
700 ARRAY (arr) = heap_generator_2 (p, rmod, rsiz, esiz);
701 BYTE_T *elem = ADDRESS (&(ARRAY (arr)));
702 for (int k = 0; k < rsiz; k++) {
703 if (alloc_sub) {
704 (*cur_sp) = pop_sp;
705 genie_generator_stowed (NEXT (p), &(elem[k * esiz]), NO_VAR, cur_sp);
706 top_sp = *cur_sp;
707 } else if (alloc_str) {
708 *(A68_REF *) (&(elem[k * esiz])) = empty_string (p);
709 }
710 }
711 (*cur_sp) = top_sp;
712 }
713 *(A68_REF *) addr = desc;
714 return;
715 }
716 }
717
718 //! @brief Generate space and push a REF.
719
720 void genie_generator_internal (NODE_T * p, MOID_T * ref_mode, TAG_T * tag, LEAP_T leap, ADDR_T sp)
721 {
722 // Set up a REF MODE object, either in the stack or in the heap.
723 MOID_T *mode = SUB (ref_mode);
724 A68_REF name = nil_ref;
725 if (leap == LOC_SYMBOL) {
726 STATUS (&name) = (STATUS_MASK_T) (INIT_MASK | IN_FRAME_MASK);
727 REF_HANDLE (&name) = (A68_HANDLE *) & nil_handle;
728 OFFSET (&name) = A68_FP + FRAME_INFO_SIZE + OFFSET (tag);
729 REF_SCOPE (&name) = A68_FP;
730 } else if (leap == -LOC_SYMBOL && NON_LOCAL (p) != NO_TABLE) {
731 name = heap_generator (p, mode, SIZE (mode));
732 ADDR_T lev;
733 FOLLOW_SL (lev, LEVEL (NON_LOCAL (p)));
734 REF_SCOPE (&name) = lev;
735 } else if (leap == -LOC_SYMBOL) {
736 name = heap_generator (p, mode, SIZE (mode));
737 REF_SCOPE (&name) = A68_FP;
738 } else if (leap == HEAP_SYMBOL || leap == -HEAP_SYMBOL) {
739 name = heap_generator (p, mode, SIZE (mode));
740 REF_SCOPE (&name) = PRIMAL_SCOPE;
741 } else if (leap == NEW_SYMBOL || leap == -NEW_SYMBOL) {
742 name = heap_generator (p, mode, SIZE (mode));
743 REF_SCOPE (&name) = PRIMAL_SCOPE;
744 } else {
745 ABEND (A68_TRUE, ERROR_INTERNAL_CONSISTENCY, __func__);
746 }
747 if (HAS_ROWS (mode)) {
748 ADDR_T cur_sp = sp;
749 genie_generator_stowed (p, ADDRESS (&name), NO_VAR, &cur_sp);
750 }
751 PUSH_REF (p, name);
752 }
753
754 //! @brief Push a name refering to allocated space.
755
756 PROP_T genie_generator (NODE_T * p)
757 {
758 ADDR_T pop_sp = A68_SP;
759 if (NEXT_SUB (p) != NO_NODE) {
760 genie_generator_bounds (NEXT_SUB (p));
761 }
762 genie_generator_internal (NEXT_SUB (p), MOID (p), TAX (p), -ATTRIBUTE (SUB (p)), pop_sp);
763 A68_REF z;
764 POP_REF (p, &z);
765 A68_SP = pop_sp;
766 PUSH_REF (p, z);
767 PROP_T self;
768 UNIT (&self) = genie_generator;
769 SOURCE (&self) = p;
770 return self;
771 }
772
773 // Control of C heap
774
775 //! @brief Discard_heap.
776
777 void discard_heap (void)
778 {
779 a68_free (A68_HEAP);
780 A68 (fixed_heap_pointer) = 0;
781 A68 (temp_heap_pointer) = 0;
782 }
