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 2001-2026 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 Check overflow at size multiplication.
88
89 BOOL_T size_mul_overflow (size_t u, size_t v)
90 {
91 if (u == 0 || v == 0) {
92 return (A68G_FALSE);
93 } else {
94 return v > (MAX_MEM_SIZE / u);
95 }
96 }
97
98 //! @brief PROC VOID gc heap
99
100 void genie_gc_heap (NODE_T * p)
101 {
102 gc_heap (p, A68G_FP);
103 }
104
105 //! @brief PROC VOID preemptive gc heap
106
107 void genie_preemptive_gc_heap (NODE_T * p)
108 {
109 if (A68G_GC (preemptive)) {
110 gc_heap (p, A68G_FP);
111 A68G_GC (preemptive) = A68G_FALSE;
112 }
113 }
114
115 //! @brief INT blocks
116
117 void genie_block (NODE_T * p)
118 {
119 PUSH_VALUE (p, 0, A68G_INT);
120 }
121
122 //! @brief INT garbage collections
123
124 void genie_garbage_collections (NODE_T * p)
125 {
126 PUSH_VALUE (p, A68G_GC (sweeps), A68G_INT);
127 }
128
129 //! @brief INT garbage refused
130
131 void genie_garbage_refused (NODE_T * p)
132 {
133 PUSH_VALUE (p, A68G_GC (refused), A68G_INT);
134 }
135
136 //! @brief LONG INT garbage freed
137
138 void genie_garbage_freed (NODE_T * p)
139 {
140 PUSH_VALUE (p, A68G_GC (total), A68G_INT);
141 }
142
143 //! @brief REAL garbage seconds
144
145 void genie_garbage_seconds (NODE_T * p)
146 {
147 // Note that this timing is a rough cut.
148 PUSH_VALUE (p, A68G_GC (seconds), A68G_REAL);
149 }
150
151 //! @brief Size available for an object in the heap.
152
153 size_t heap_available (void)
154 {
155 if (A68G (temp_heap_pointer) > A68G_HP) {
156 return A68G (temp_heap_pointer) - A68G_HP;
157 } else {
158 return 0;
159 }
160 }
161
162 //! @brief Initialise heap management.
163
164 void genie_init_heap (NODE_T * p)
165 {
166 (void) p;
167 if (A68G_HEAP == NO_BYTE) {
168 diagnostic (A68G_RUNTIME_ERROR, TOP_NODE (&A68G_JOB), ERROR_MEMORY_FULL);
169 exit_genie (TOP_NODE (&A68G_JOB), A68G_RUNTIME_ERROR);
170 }
171 if (A68G_HANDLES == NO_BYTE) {
172 diagnostic (A68G_RUNTIME_ERROR, TOP_NODE (&A68G_JOB), ERROR_MEMORY_FULL);
173 exit_genie (TOP_NODE (&A68G_JOB), A68G_RUNTIME_ERROR);
174 }
175 A68G_GC (seconds) = 0;
176 A68G_GC (total) = 0;
177 A68G_GC (sweeps) = 0;
178 A68G_GC (refused) = 0;
179 A68G_GC (preemptive) = A68G_FALSE;
180 // Make sure we have some space for an A68 heap.
181 ABEND ((A68G (fixed_heap_pointer) + 2 * A68G (storage_overhead)) >= A68G (temp_heap_pointer), ERROR_MEMORY_FULL, NO_TEXT);
182 A68G_HP = A68G (fixed_heap_pointer);
183 A68G (heap_is_fluid) = A68G_FALSE;
184 // Assign handle space.
185 A68G_HANDLE *z = (A68G_HANDLE *) A68G_HANDLES;
186 A68G_GC (available_handles) = z;
187 A68G_GC (busy_handles) = NO_HANDLE;
188 size_t N = A68G (handle_pool_size) / SIZE_ALIGNED (A68G_HANDLE);
189 A68G_GC (free_handles) = N;
190 A68G_GC (max_handles) = N;
191 for (int k = 0; k < N; k++) {
192 STATUS (&(z[k])) = NULL_MASK;
193 POINTER (&(z[k])) = NO_BYTE;
194 SIZE (&(z[k])) = 0;
195 NEXT (&z[k]) = (k == N - 1 ? NO_HANDLE : &z[k + 1]);
196 PREVIOUS (&z[k]) = (k == 0 ? NO_HANDLE : &z[k - 1]);
197 }
198 }
199
200 //! @brief Whether mode must be coloured.
201
202 BOOL_T moid_needs_colouring (MOID_T * m)
203 {
204 if (IS_REF (m)) {
205 return A68G_TRUE;
206 } else if (IS (m, PROC_SYMBOL)) {
207 return A68G_TRUE;
208 } else if (IS_FLEX (m) || IS_ROW (m)) {
209 return A68G_TRUE;
210 } else if (IS_STRUCT (m) || IS_UNION (m)) {
211 for (PACK_T *p = PACK (m); p != NO_PACK; FORWARD (p)) {
212 if (moid_needs_colouring (MOID (p))) {
213 return A68G_TRUE;
214 }
215 }
216 return A68G_FALSE;
217 } else if (m == M_SIMPLIN || m == M_SIMPLOUT) {
218 return A68G_TRUE;
219 } else if (m == M_SOUND) {
220 return A68G_TRUE;
221 } else {
222 return A68G_FALSE;
223 }
224 }
225
226 //! @brief Colour all elements of a row.
227
228 void colour_row_elements (A68G_REF * z)
229 {
230 A68G_ARRAY *arr; A68G_TUPLE *tup;
231 GET_DESCRIPTOR (arr, tup, z);
232 int dim = DIM (arr);
233 MOID_T *df = DEFLEX (SLICE (arr));
234 BYTE_T *elem = ADDRESS (&ARRAY (arr));
235 if (get_row_size (tup, dim) == 0) {
236 // Empty rows have a ghost elements.
237 colour_object (&elem[0], df);
238 } else {
239 // Colour all elements.
240 initialise_internal_index (tup, dim);
241 BOOL_T done = A68G_FALSE;
242 while (!done) {
243 ADDR_T index = calculate_internal_index (tup, dim);
244 colour_object (&elem[ROW_ELEMENT (arr, index)], df);
245 done = increment_internal_index (tup, dim);
246 }
247 }
248 }
249
250 //! @brief Colour an (active) object.
251
252 void colour_object (BYTE_T * item, MOID_T * m)
253 {
254 if (item == NO_BYTE || m == NO_MOID) {
255 return;
256 }
257 if (!moid_needs_colouring (m)) {
258 return;
259 }
260 // Deeply recursive objects might exhaust the stack.
261 LOW_STACK_ALERT (NO_NODE);
262 if (IS_REF (m)) {
263 // REF AMODE colour pointer and object to which it refers.
264 A68G_REF *z = (A68G_REF *) item;
265 if (INITIALISED (z) && IS_IN_HEAP (z)) {
266 if (STATUS_TEST (REF_HANDLE (z), COOKIE_MASK)) {
267 return;
268 }
269 STATUS_SET (REF_HANDLE (z), (COOKIE_MASK | COLOUR_MASK));
270 if (!IS_NIL (*z)) {
271 colour_object (ADDRESS (z), SUB (m));
272 }
273 // STATUS_CLEAR (REF_HANDLE (z), COOKIE_MASK);.
274 }
275 } else if (IS_FLEXETY_ROW (m)) {
276 // Claim the descriptor and the row itself.
277 A68G_REF *z = (A68G_REF *) item;
278 if (INITIALISED (z) && IS_IN_HEAP (z)) {
279 if (STATUS_TEST (REF_HANDLE (z), COOKIE_MASK)) {
280 return;
281 }
282 // An array is ALWAYS in the heap.
283 STATUS_SET (REF_HANDLE (z), (COOKIE_MASK | COLOUR_MASK));
284 A68G_ARRAY *arr; A68G_TUPLE *tup;
285 GET_DESCRIPTOR (arr, tup, z);
286 if (REF_HANDLE (&(ARRAY (arr))) != NO_HANDLE) {
287 // Assume row initialisation.
288 MOID_T *n = DEFLEX (m);
289 STATUS_SET (REF_HANDLE (&(ARRAY (arr))), COLOUR_MASK);
290 if (moid_needs_colouring (SUB (n))) {
291 colour_row_elements (z);
292 }
293 }
294 // STATUS_CLEAR (REF_HANDLE (z), COOKIE_MASK);.
295 (void) tup;
296 }
297 } else if (IS_STRUCT (m)) {
298 // STRUCTures - colour fields.
299 for (PACK_T *p = PACK (m); p != NO_PACK; FORWARD (p)) {
300 colour_object (&item[OFFSET (p)], MOID (p));
301 }
302 } else if (IS_UNION (m) || m == M_SIMPLIN || m == M_SIMPLOUT) {
303 // UNIONs - a united object may contain a value that needs colouring.
304 // SIMPLIN and SIMPLOUT are UNIONs.
305 A68G_UNION *z = (A68G_UNION *) item;
306 if (INITIALISED (z)) {
307 MOID_T *united_moid = (MOID_T *) VALUE (z);
308 colour_object (&item[A68G_UNION_SIZE], united_moid);
309 }
310 } else if (IS (m, PROC_SYMBOL)) {
311 // PROCs - save a locale and the objects it points to.
312 A68G_PROCEDURE *z = (A68G_PROCEDURE *) item;
313 if (INITIALISED (z) && LOCALE (z) != NO_HANDLE && !(STATUS_TEST (LOCALE (z), COOKIE_MASK))) {
314 BYTE_T *u = POINTER (LOCALE (z));
315 STATUS_SET (LOCALE (z), (COOKIE_MASK | COLOUR_MASK));
316 for (PACK_T *s = PACK (MOID (z)); s != NO_PACK; FORWARD (s)) {
317 if (VALUE ((A68G_BOOL *) & u[0]) == A68G_TRUE) {
318 colour_object (&u[SIZE (M_BOOL)], MOID (s));
319 }
320 u = &(u[SIZE (M_BOOL) + SIZE (MOID (s))]);
321 }
322 // STATUS_CLEAR (LOCALE (z), COOKIE_MASK);.
323 }
324 } else if (m == M_SOUND) {
325 // Claim the data of a SOUND object, that is in the heap.
326 A68G_SOUND *w = (A68G_SOUND *) item;
327 if (INITIALISED (w)) {
328 STATUS_SET (REF_HANDLE (&(DATA (w))), (COOKIE_MASK | COLOUR_MASK));
329 }
330 } else {
331 ABEND (A68G_TRUE, ERROR_INTERNAL_CONSISTENCY, moid_to_string (m, 80, NO_NODE));
332 }
333 }
334
335 //! @brief Colour active objects in the heap.
336
337 void colour_heap (ADDR_T fp)
338 {
339 while (fp != 0) {
340 NODE_T *p = FRAME_TREE (fp);
341 TABLE_T *t = TABLE (p);
342 if (t != NO_TABLE) {
343 for (TAG_T *q = IDENTIFIERS (t); q != NO_TAG; FORWARD (q)) {
344 colour_object (FRAME_LOCAL (fp, OFFSET (q)), MOID (q));
345 }
346 for (TAG_T *q = ANONYMOUS (t); q != NO_TAG; FORWARD (q)) {
347 colour_object (FRAME_LOCAL (fp, OFFSET (q)), MOID (q));
348 }
349 }
350 fp = FRAME_DYNAMIC_LINK (fp);
351 }
352 }
353
354 //! @brief Join all active blocks in the heap.
355
356 void defragment_heap (void)
357 {
358 // Free handles.
359 A68G_HANDLE *z = A68G_GC (busy_handles);
360 while (z != NO_HANDLE) {
361 if (!(STATUS_TEST (z, COLOUR_MASK)) && !(STATUS_TEST (z, BLOCK_GC_MASK))) {
362 A68G_HANDLE *y = NEXT (z);
363 if (PREVIOUS (z) == NO_HANDLE) {
364 A68G_GC (busy_handles) = NEXT (z);
365 } else {
366 NEXT (PREVIOUS (z)) = NEXT (z);
367 }
368 if (NEXT (z) != NO_HANDLE) {
369 PREVIOUS (NEXT (z)) = PREVIOUS (z);
370 }
371 NEXT (z) = A68G_GC (available_handles);
372 PREVIOUS (z) = NO_HANDLE;
373 if (NEXT (z) != NO_HANDLE) {
374 PREVIOUS (NEXT (z)) = z;
375 }
376 A68G_GC (available_handles) = z;
377 STATUS_CLEAR (z, ALLOCATED_MASK);
378 A68G_GC (freed) += SIZE (z);
379 A68G_GC (free_handles)++;
380 z = y;
381 } else {
382 FORWARD (z);
383 }
384 }
385 // There can be no uncoloured allocated handle.
386 for (z = A68G_GC (busy_handles); z != NO_HANDLE; FORWARD (z)) {
387 ABEND (!(STATUS_TEST (z, COLOUR_MASK)) && !(STATUS_TEST (z, BLOCK_GC_MASK)), ERROR_INTERNAL_CONSISTENCY, NO_TEXT);
388 }
389 // Defragment the heap.
390 A68G_HP = A68G (fixed_heap_pointer);
391 for (z = A68G_GC (busy_handles); z != NO_HANDLE && NEXT (z) != NO_HANDLE; FORWARD (z)) {
392 ;
393 }
394 for (; z != NO_HANDLE; BACKWARD (z)) {
395 BYTE_T *dst = HEAP_ADDRESS (A68G_HP);
396 if (dst != POINTER (z)) {
397 MOVE (dst, POINTER (z), SIZE (z));
398 }
399 STATUS_CLEAR (z, (COLOUR_MASK | COOKIE_MASK));
400 POINTER (z) = dst;
401 A68G_HP += (SIZE (z));
402 ABEND (A68G_HP % A68G_ALIGNMENT != 0, ERROR_ALIGNMENT, NO_TEXT);
403 }
404 }
405
406 //! @brief Clean up garbage and defragment the heap.
407
408 void gc_heap (NODE_T * p, ADDR_T fp)
409 {
410 // Must start with fp = current frame_pointer.
411 A68G_HANDLE *z;
412 REAL_T t0, t1;
413 #if defined (BUILD_PARALLEL_CLAUSE)
414 if (OTHER_THREAD (FRAME_THREAD_ID (A68G_FP), A68G_PAR (main_thread_id))) {
415 A68G_GC (refused)++;
416 return;
417 }
418 #endif
419 if (STATUS_TEST (p, BLOCK_GC_MASK)) {
420 A68G_GC (refused)++;
421 return;
422 }
423 if (OPTION_CONSERVATIVE_GC (&A68G_JOB) == A68G_GC_HALT) {
424 A68G_GC (refused)++;
425 return;
426 }
427 if (OPTION_CONSERVATIVE_GC (&A68G_JOB) == A68G_GC_SAFE && (A68G_GC (sema) > 0)) {
428 A68G_GC (refused)++;
429 return;
430 }
431 // Take no risk when intermediate results are on the stack.
432 if (OPTION_CONSERVATIVE_GC (&A68G_JOB) && (A68G_SP != A68G (stack_start))) {
433 A68G_GC (refused)++;
434 return;
435 }
436 // Give it a whirl then.
437 t0 = seconds ();
438 // Unfree handles are subject to inspection.
439 // Release them all before colouring.
440 for (z = A68G_GC (busy_handles); z != NO_HANDLE; FORWARD (z)) {
441 STATUS_CLEAR (z, (COLOUR_MASK | COOKIE_MASK));
442 }
443 // Pour paint into the heap to reveal active objects.
444 colour_heap (fp);
445 // Start freeing and compacting.
446 A68G_GC (freed) = 0;
447 defragment_heap ();
448 // Stats and logging.
449 A68G_GC (total) += A68G_GC (freed);
450 A68G_GC (sweeps)++;
451 A68G_GC (preemptive) = A68G_FALSE;
452 t1 = seconds ();
453 // C optimiser can make last digit differ, so next condition is
454 // needed to determine a positive time difference
455 if ((t1 - t0) > ((REAL_T) A68G (clock_res) / 2.0)) {
456 A68G_GC (seconds) += (t1 - t0);
457 } else {
458 A68G_GC (seconds) += ((REAL_T) A68G (clock_res) / 2.0);
459 }
460 // Call the event handler.
461 genie_call_event_routine (p, M_PROC_VOID, &A68G (on_gc_event), A68G_SP, A68G_FP);
462 }
463
464 //! @brief Yield a handle that will point to a block in the heap.
465
466 A68G_HANDLE *give_handle (NODE_T * p, MOID_T * a68m)
467 {
468 if (A68G_GC (available_handles) != NO_HANDLE) {
469 A68G_HANDLE *x = A68G_GC (available_handles);
470 A68G_GC (available_handles) = NEXT (x);
471 if (A68G_GC (available_handles) != NO_HANDLE) {
472 PREVIOUS (A68G_GC (available_handles)) = NO_HANDLE;
473 }
474 STATUS (x) = ALLOCATED_MASK;
475 POINTER (x) = NO_BYTE;
476 SIZE (x) = 0;
477 MOID (x) = a68m;
478 NEXT (x) = A68G_GC (busy_handles);
479 PREVIOUS (x) = NO_HANDLE;
480 if (NEXT (x) != NO_HANDLE) {
481 PREVIOUS (NEXT (x)) = x;
482 }
483 A68G_GC (busy_handles) = x;
484 A68G_GC (free_handles)--;
485 return x;
486 } else {
487 // Do not auto-GC! Really, don't.
488 diagnostic (A68G_RUNTIME_ERROR, p, ERROR_MEMORY_FULL);
489 exit_genie (p, A68G_RUNTIME_ERROR);
490 }
491 return NO_HANDLE;
492 }
493
494 //! @brief Allocate heap for an object of indicated mode.
495
496 A68G_REF heap_generator (NODE_T * p, MOID_T * mode, size_t size)
497 {
498 if (size == 0) {
499 // Empty arrays for instance can have zero length. If we allow zero length,
500 // two REFs to not-equivalent objects could point to a same heap area.
501 // That is harmless in A68G, but it feels conceptually wrong ;-).
502 size = 1;
503 }
504 size = A68G_ALIGN (size);
505 if (heap_available () >= size) {
506 A68G_REF z;
507 STATUS (&z) = (STATUS_MASK_T) (INIT_MASK | IN_HEAP_MASK);
508 OFFSET (&z) = 0;
509 A68G_HANDLE *x = give_handle (p, mode);
510 SIZE (x) = size;
511 POINTER (x) = HEAP_ADDRESS (A68G_HP);
512 FILL (POINTER (x), 0, size);
513 REF_SCOPE (&z) = PRIMAL_SCOPE;
514 REF_HANDLE (&z) = x;
515 ABEND (((size_t) ADDRESS (&z)) % A68G_ALIGNMENT != 0, ERROR_ALIGNMENT, NO_TEXT);
516 A68G_HP += size;
517 // Raise a flag for a preemptive sweep at a convenient moment.
518 if (heap_available () < (A68G (storage_overhead) + size) || A68G_GC (free_handles) < 100) {
519 // Emergency break.
520 A68G_GC (preemptive) = A68G_TRUE;
521 } else {
522 // General case.
523 REAL_T _f_ = (REAL_T) A68G_HP / (REAL_T) heap_available ();
524 REAL_T _g_ = (REAL_T) (A68G_GC (max_handles) - A68G_GC (free_handles)) / (REAL_T) A68G_GC (max_handles);
525 if (_f_ > PREEMPTIVE_FRACTION || _g_ > PREEMPTIVE_FRACTION) {
526 A68G_GC (preemptive) = A68G_TRUE;
527 }
528 }
529 return z;
530 } else {
531 // Do not auto-GC! Really, don't.
532 diagnostic (A68G_RUNTIME_ERROR, p, ERROR_MEMORY_FULL);
533 exit_genie (p, A68G_RUNTIME_ERROR);
534 return nil_ref;
535 }
536 }
537
538 //! @brief Allocate heap for an object of indicated mode.
539
540 A68G_REF heap_generator_2 (NODE_T * p, MOID_T * mode, size_t len, size_t size)
541 {
542 if (len == 0 || size == 0) {
543 return heap_generator (p, mode, 0);
544 } else if (size_mul_overflow (len, size)) {
545 diagnostic (A68G_RUNTIME_ERROR, p, ERROR_OBJECT_TOO_LARGE, mode);
546 exit_genie (p, A68G_RUNTIME_ERROR);
547 } else {
548 return heap_generator (p, mode, len * size);
549 }
550 return nil_ref;
551 }
552
553 //! @brief Allocate heap for an object of indicated mode.
554
555 A68G_REF heap_generator_3 (NODE_T * p, MOID_T * mode, size_t len1, size_t len2, size_t size)
556 {
557 if (len1 == 0 || len2 == 0) {
558 return heap_generator (p, mode, 0);
559 } else if (size_mul_overflow (len1, len2)) {
560 diagnostic (A68G_RUNTIME_ERROR, p, ERROR_OBJECT_TOO_LARGE, mode);
561 exit_genie (p, A68G_RUNTIME_ERROR);
562 } else {
563 return heap_generator_2 (p, mode, len1 * len2, size);
564 }
565 return nil_ref;
566 }
567
568 // Following implements the generator.
569
570 //! @brief Whether a moid needs work in allocation.
571
572 BOOL_T mode_needs_allocation (MOID_T * m)
573 {
574 if (IS_UNION (m)) {
575 return A68G_FALSE;
576 } else {
577 return HAS_ROWS (m);
578 }
579 }
580
581 //! @brief Prepare bounds for a row.
582
583 void genie_compute_bounds (NODE_T * p)
584 {
585 for (; p != NO_NODE; FORWARD (p)) {
586 if (IS (p, BOUNDS_LIST)) {
587 genie_compute_bounds (SUB (p));
588 } else if (IS (p, BOUND)) {
589 genie_compute_bounds (SUB (p));
590 } else if (IS (p, UNIT)) {
591 if (NEXT (p) != NO_NODE && (is_one_of (NEXT (p), COLON_SYMBOL, DOTDOT_SYMBOL, STOP))) {
592 GENIE_UNIT (p);
593 p = NEXT_NEXT (p);
594 } else {
595 // Default lower bound.
596 PUSH_VALUE (p, 1, A68G_INT);
597 }
598 GENIE_UNIT (p);
599 }
600 }
601 }
602
603 //! @brief Prepare bounds for a row.
604
605 void genie_generator_bounds (NODE_T * p)
606 {
607 LOW_STACK_ALERT (p);
608 for (; p != NO_NODE; FORWARD (p)) {
609 if (IS (p, BOUNDS)) {
610 genie_compute_bounds (SUB (p));
611 } else if (IS (p, INDICANT) && IS_LITERALLY (p, "STRING")) {
612 return;
613 } else if (IS (p, INDICANT)) {
614 if (TAX (p) != NO_TAG && HAS_ROWS (MOID (TAX (p)))) {
615 // Continue from definition at MODE A = ... in the tree.
616 genie_generator_bounds (DEF_NODE (p));
617 }
618 } else if (IS (p, DECLARER) && !mode_needs_allocation (MOID (p))) {
619 return;
620 } else {
621 genie_generator_bounds (SUB (p));
622 }
623 }
624 }
625
626 //! @brief Allocate a structure.
627
628 void genie_generator_field (NODE_T * p, BYTE_T ** faddr, NODE_T ** decl, ADDR_T * cur_sp, ADDR_T * top_sp)
629 {
630 for (; p != NO_NODE; FORWARD (p)) {
631 if (IS (p, STRUCTURED_FIELD)) {
632 genie_generator_field (SUB (p), faddr, decl, cur_sp, top_sp);
633 }
634 if (IS (p, DECLARER)) {
635 (*decl) = SUB (p);
636 FORWARD (p);
637 }
638 if (IS (p, FIELD_IDENTIFIER)) {
639 MOID_T *fmoid = MOID (*decl);
640 if (HAS_ROWS (fmoid) && ISNT (fmoid, UNION_SYMBOL)) {
641 ADDR_T pop_sp = *cur_sp;
642 genie_generator_stowed (*decl, *faddr, NO_REF, cur_sp);
643 *top_sp = *cur_sp;
644 *cur_sp = pop_sp;
645 }
646 (*faddr) += SIZE (fmoid);
647 }
648 }
649 }
650
651 //! @brief Allocate a structure.
652
653 void genie_generator_struct (NODE_T * p, BYTE_T ** faddr, ADDR_T * cur_sp)
654 {
655 for (; p != NO_NODE; FORWARD (p)) {
656 if (IS (p, STRUCTURED_FIELD_LIST)) {
657 genie_generator_struct (SUB (p), faddr, cur_sp);
658 } else if (IS (p, STRUCTURED_FIELD)) {
659 NODE_T *decl = NO_NODE;
660 ADDR_T top_sp = *cur_sp;
661 genie_generator_field (SUB (p), faddr, &decl, cur_sp, &top_sp);
662 *cur_sp = top_sp;
663 }
664 }
665 }
666
667 //! @brief Allocate a stowed object.
668
669 void genie_generator_stowed (NODE_T * p, BYTE_T * addr, NODE_T ** decl, ADDR_T * cur_sp)
670 {
671 if (p == NO_NODE) {
672 return;
673 } else if (IS (p, INDICANT) && IS_LITERALLY (p, "STRING")) {
674 // The standard prelude definition is hard coded here.
675 *((A68G_REF *) addr) = empty_string (p);
676 return;
677 } else if (IS (p, INDICANT) && TAX (p) != NO_TAG) {
678 // Continue from definition at MODE A = ... in the tree.
679 genie_generator_stowed (DEF_NODE (p), addr, decl, cur_sp);
680 return;
681 } else if (IS (p, DECLARER) && mode_needs_allocation (MOID (p))) {
682 genie_generator_stowed (SUB (p), addr, decl, cur_sp);
683 return;
684 } else if (IS_STRUCT (p)) {
685 BYTE_T *faddr = addr;
686 genie_generator_struct (SUB_NEXT (p), &faddr, cur_sp);
687 return;
688 } else if (IS_FLEX (p)) {
689 genie_generator_stowed (NEXT (p), addr, decl, cur_sp);
690 return;
691 } else if (IS (p, BOUNDS)) {
692 A68G_REF desc;
693 MOID_T *rmod = MOID (p), *smod = MOID (NEXT (p));
694 BYTE_T *bounds = STACK_ADDRESS (*cur_sp);
695 int dim = DIM (DEFLEX (rmod)), esiz = SIZE (smod), rsiz = 1;
696 BOOL_T alloc_sub = A68G_FALSE, alloc_str = A68G_FALSE;
697 NODE_T *in = SUB_NEXT (p);
698 if (IS (in, INDICANT) && IS_LITERALLY (in, "STRING")) {
699 alloc_str = A68G_TRUE;
700 alloc_sub = A68G_FALSE;
701 } else {
702 alloc_sub = mode_needs_allocation (smod);
703 alloc_str = A68G_FALSE;
704 }
705 desc = heap_generator (p, rmod, DESCRIPTOR_SIZE (dim));
706 A68G_ARRAY *arr; A68G_TUPLE *tup;
707 GET_DESCRIPTOR (arr, tup, &desc);
708 for (int k = 0; k < dim; k++) {
709 CHECK_INIT (p, INITIALISED ((A68G_INT *) bounds), M_INT);
710 LWB (&tup[k]) = VALUE ((A68G_INT *) bounds);
711 bounds += SIZE (M_INT);
712 CHECK_INIT (p, INITIALISED ((A68G_INT *) bounds), M_INT);
713 UPB (&tup[k]) = VALUE ((A68G_INT *) bounds);
714 bounds += SIZE (M_INT);
715 SPAN (&tup[k]) = rsiz;
716 SHIFT (&tup[k]) = LWB (&tup[k]) * SPAN (&tup[k]);
717 rsiz *= ROW_SIZE (&tup[k]);
718 }
719 DIM (arr) = dim;
720 SLICE (arr) = smod;
721 SLICE_SIZE (arr) = esiz;
722 SLICE_OFFSET (arr) = 0;
723 FIELD_OFFSET (arr) = 0;
724 (*cur_sp) += (dim * 2 * SIZE (M_INT));
725 // Generate a new row. STRING is handled explicitly.
726 if (rsiz == 0) {
727 // Generate a ghost element.
728 ADDR_T top_sp = *cur_sp;
729 ARRAY (arr) = heap_generator (p, rmod, esiz);
730 BYTE_T *elem = ADDRESS (&(ARRAY (arr)));
731 if (alloc_sub) {
732 genie_generator_stowed (NEXT (p), &(elem[0]), NO_REF, cur_sp);
733 top_sp = *cur_sp;
734 } else if (alloc_str) {
735 *(A68G_REF *) elem = empty_string (p);
736 }
737 (*cur_sp) = top_sp;
738 } else {
739 ADDR_T pop_sp = *cur_sp, top_sp = *cur_sp;
740 ARRAY (arr) = heap_generator_2 (p, rmod, rsiz, esiz);
741 BYTE_T *elem = ADDRESS (&(ARRAY (arr)));
742 for (int k = 0; k < rsiz; k++) {
743 if (alloc_sub) {
744 (*cur_sp) = pop_sp;
745 genie_generator_stowed (NEXT (p), &(elem[k * esiz]), NO_REF, cur_sp);
746 top_sp = *cur_sp;
747 } else if (alloc_str) {
748 *(A68G_REF *) (&(elem[k * esiz])) = empty_string (p);
749 }
750 }
751 (*cur_sp) = top_sp;
752 }
753 *(A68G_REF *) addr = desc;
754 return;
755 }
756 }
757
758 //! @brief Generate space and push a REF.
759
760 void genie_generator_internal (NODE_T * p, MOID_T * ref_mode, TAG_T * tag, LEAP_T leap, ADDR_T sp)
761 {
762 // Set up a REF MODE object, either in the stack or in the heap.
763 MOID_T *mode = SUB (ref_mode);
764 A68G_REF name = nil_ref;
765 if (leap == LOC_SYMBOL) {
766 STATUS (&name) = (STATUS_MASK_T) (INIT_MASK | IN_FRAME_MASK);
767 REF_HANDLE (&name) = (A68G_HANDLE *) & nil_handle;
768 OFFSET (&name) = A68G_FP + FRAME_INFO_SIZE + OFFSET (tag);
769 REF_SCOPE (&name) = A68G_FP;
770 } else if (leap == -LOC_SYMBOL && NON_LOCAL (p) != NO_TABLE) {
771 name = heap_generator (p, mode, SIZE (mode));
772 ADDR_T lev;
773 FOLLOW_SL (lev, LEVEL (NON_LOCAL (p)));
774 REF_SCOPE (&name) = lev;
775 } else if (leap == -LOC_SYMBOL) {
776 name = heap_generator (p, mode, SIZE (mode));
777 REF_SCOPE (&name) = A68G_FP;
778 } else if (leap == HEAP_SYMBOL || leap == -HEAP_SYMBOL) {
779 name = heap_generator (p, mode, SIZE (mode));
780 REF_SCOPE (&name) = PRIMAL_SCOPE;
781 } else if (leap == NEW_SYMBOL || leap == -NEW_SYMBOL) {
782 name = heap_generator (p, mode, SIZE (mode));
783 REF_SCOPE (&name) = PRIMAL_SCOPE;
784 } else {
785 ABEND (A68G_TRUE, ERROR_INTERNAL_CONSISTENCY, NO_TEXT);
786 }
787 if (HAS_ROWS (mode)) {
788 ADDR_T cur_sp = sp;
789 genie_generator_stowed (p, ADDRESS (&name), NO_REF, &cur_sp);
790 }
791 PUSH_REF (p, name);
792 }
793
794 //! @brief Push a name refering to allocated space.
795
796 PROP_T genie_generator (NODE_T * p)
797 {
798 ADDR_T pop_sp = A68G_SP;
799 if (NEXT_SUB (p) != NO_NODE) {
800 genie_generator_bounds (NEXT_SUB (p));
801 }
802 genie_generator_internal (NEXT_SUB (p), MOID (p), TAX (p), -ATTRIBUTE (SUB (p)), pop_sp);
803 A68G_REF z;
804 POP_REF (p, &z);
805 A68G_SP = pop_sp;
806 PUSH_REF (p, z);
807 PROP_T self;
808 UNIT (&self) = genie_generator;
809 SOURCE (&self) = p;
810 return self;
811 }
812
813 // Control of C heap
814
815 //! @brief Discard_heap.
816
817 void discard_heap (void)
818 {
819 a68g_free (A68G_HEAP);
820 A68G (fixed_heap_pointer) = 0;
821 A68G (temp_heap_pointer) = 0;
822 }
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© 2002-2026 J.M. van der Veer (jmvdveer@xs4all.nl)
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