Commit | Line | Data |
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dcfdbac7 | 1 | /* Block-relocating memory allocator. |
c6c5df7f | 2 | Copyright (C) 1993 Free Software Foundation, Inc. |
dcfdbac7 JB |
3 | |
4 | This file is part of GNU Emacs. | |
5 | ||
6 | GNU Emacs is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 1, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU Emacs is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU Emacs; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | /* NOTES: | |
21 | ||
22 | Only relocate the blocs neccessary for SIZE in r_alloc_sbrk, | |
23 | rather than all of them. This means allowing for a possible | |
24 | hole between the first bloc and the end of malloc storage. */ | |
25 | ||
2c46d29f | 26 | #ifdef emacs |
aef4d570 | 27 | |
dcfdbac7 | 28 | #include "config.h" |
956ace37 | 29 | #include "lisp.h" /* Needed for VALBITS. */ |
2c46d29f | 30 | |
aef4d570 RM |
31 | #undef NULL |
32 | ||
f275fd9a RS |
33 | /* The important properties of this type are that 1) it's a pointer, and |
34 | 2) arithmetic on it should work as if the size of the object pointed | |
35 | to has a size of 1. */ | |
a8c0e5ea | 36 | #if 0 /* Arithmetic on void* is a GCC extension. */ |
f275fd9a RS |
37 | #ifdef __STDC__ |
38 | typedef void *POINTER; | |
39 | #else | |
1df181b6 RM |
40 | |
41 | #ifdef HAVE_CONFIG_H | |
42 | #include "config.h" | |
43 | #endif | |
44 | ||
f275fd9a | 45 | typedef char *POINTER; |
1df181b6 | 46 | |
f275fd9a | 47 | #endif |
a8c0e5ea RS |
48 | #endif /* 0 */ |
49 | ||
50 | /* Unconditionally use char * for this. */ | |
51 | typedef char *POINTER; | |
f275fd9a RS |
52 | |
53 | typedef unsigned long SIZE; | |
54 | ||
2c46d29f RS |
55 | /* Declared in dispnew.c, this version doesn't screw up if regions |
56 | overlap. */ | |
57 | extern void safe_bcopy (); | |
2c46d29f | 58 | |
aef4d570 RM |
59 | #include "getpagesize.h" |
60 | ||
61 | #else /* Not emacs. */ | |
62 | ||
2c46d29f | 63 | #include <stddef.h> |
aef4d570 | 64 | |
2c46d29f RS |
65 | typedef size_t SIZE; |
66 | typedef void *POINTER; | |
aef4d570 | 67 | |
aef4d570 RM |
68 | #include <unistd.h> |
69 | #include <malloc.h> | |
70 | #include <string.h> | |
71 | ||
2c46d29f | 72 | #define safe_bcopy(x, y, z) memmove (y, x, z) |
2c46d29f | 73 | |
aef4d570 | 74 | #endif /* emacs. */ |
dcfdbac7 JB |
75 | |
76 | #define NIL ((POINTER) 0) | |
77 | ||
2c46d29f RS |
78 | /* A flag to indicate whether we have initialized ralloc yet. For |
79 | Emacs's sake, please do not make this local to malloc_init; on some | |
80 | machines, the dumping procedure makes all static variables | |
81 | read-only. On these machines, the word static is #defined to be | |
82 | the empty string, meaning that r_alloc_initialized becomes an | |
83 | automatic variable, and loses its value each time Emacs is started up. */ | |
84 | static int r_alloc_initialized = 0; | |
85 | ||
86 | static void r_alloc_init (); | |
dcfdbac7 | 87 | \f |
956ace37 JB |
88 | /* Declarations for working with the malloc, ralloc, and system breaks. */ |
89 | ||
bbc60227 RM |
90 | /* Function to set the real break value. */ |
91 | static POINTER (*real_morecore) (); | |
dcfdbac7 JB |
92 | |
93 | /* The break value, as seen by malloc (). */ | |
94 | static POINTER virtual_break_value; | |
95 | ||
96 | /* The break value, viewed by the relocatable blocs. */ | |
97 | static POINTER break_value; | |
98 | ||
99 | /* The REAL (i.e., page aligned) break value of the process. */ | |
100 | static POINTER page_break_value; | |
101 | ||
7516b7d5 RS |
102 | /* This is the size of a page. We round memory requests to this boundary. */ |
103 | static int page_size; | |
104 | ||
ad3bb3d2 JB |
105 | /* Whenever we get memory from the system, get this many extra bytes. This |
106 | must be a multiple of page_size. */ | |
7516b7d5 RS |
107 | static int extra_bytes; |
108 | ||
dcfdbac7 JB |
109 | /* Macros for rounding. Note that rounding to any value is possible |
110 | by changing the definition of PAGE. */ | |
111 | #define PAGE (getpagesize ()) | |
7516b7d5 RS |
112 | #define ALIGNED(addr) (((unsigned int) (addr) & (page_size - 1)) == 0) |
113 | #define ROUNDUP(size) (((unsigned int) (size) + page_size - 1) & ~(page_size - 1)) | |
114 | #define ROUND_TO_PAGE(addr) (addr & (~(page_size - 1))) | |
dcfdbac7 | 115 | \f |
956ace37 JB |
116 | /* Functions to get and return memory from the system. */ |
117 | ||
dcfdbac7 JB |
118 | /* Obtain SIZE bytes of space. If enough space is not presently available |
119 | in our process reserve, (i.e., (page_break_value - break_value)), | |
98b7fe02 | 120 | this means getting more page-aligned space from the system. |
dcfdbac7 | 121 | |
98b7fe02 JB |
122 | Return non-zero if all went well, or zero if we couldn't allocate |
123 | the memory. */ | |
124 | static int | |
dcfdbac7 JB |
125 | obtain (size) |
126 | SIZE size; | |
127 | { | |
128 | SIZE already_available = page_break_value - break_value; | |
129 | ||
130 | if (already_available < size) | |
131 | { | |
956ace37 | 132 | SIZE get = ROUNDUP (size - already_available); |
7516b7d5 RS |
133 | /* Get some extra, so we can come here less often. */ |
134 | get += extra_bytes; | |
dcfdbac7 | 135 | |
bbc60227 | 136 | if ((*real_morecore) (get) == 0) |
98b7fe02 | 137 | return 0; |
dcfdbac7 JB |
138 | |
139 | page_break_value += get; | |
140 | } | |
141 | ||
142 | break_value += size; | |
98b7fe02 JB |
143 | |
144 | return 1; | |
dcfdbac7 JB |
145 | } |
146 | ||
98b7fe02 JB |
147 | /* Obtain SIZE bytes of space and return a pointer to the new area. |
148 | If we could not allocate the space, return zero. */ | |
dcfdbac7 JB |
149 | |
150 | static POINTER | |
151 | get_more_space (size) | |
152 | SIZE size; | |
153 | { | |
154 | POINTER ptr = break_value; | |
98b7fe02 JB |
155 | if (obtain (size)) |
156 | return ptr; | |
157 | else | |
158 | return 0; | |
dcfdbac7 JB |
159 | } |
160 | ||
161 | /* Note that SIZE bytes of space have been relinquished by the process. | |
956ace37 | 162 | If SIZE is more than a page, return the space to the system. */ |
dcfdbac7 JB |
163 | |
164 | static void | |
165 | relinquish (size) | |
166 | SIZE size; | |
167 | { | |
956ace37 | 168 | POINTER new_page_break; |
7516b7d5 | 169 | int excess; |
dcfdbac7 | 170 | |
956ace37 JB |
171 | break_value -= size; |
172 | new_page_break = (POINTER) ROUNDUP (break_value); | |
7516b7d5 | 173 | excess = (char *) page_break_value - (char *) new_page_break; |
956ace37 | 174 | |
7516b7d5 | 175 | if (excess > extra_bytes * 2) |
dcfdbac7 | 176 | { |
7516b7d5 RS |
177 | /* Keep extra_bytes worth of empty space. |
178 | And don't free anything unless we can free at least extra_bytes. */ | |
179 | if ((*real_morecore) (extra_bytes - excess) == 0) | |
dcfdbac7 JB |
180 | abort (); |
181 | ||
7516b7d5 | 182 | page_break_value += extra_bytes - excess; |
dcfdbac7 JB |
183 | } |
184 | ||
956ace37 JB |
185 | /* Zero the space from the end of the "official" break to the actual |
186 | break, so that bugs show up faster. */ | |
187 | bzero (break_value, ((char *) page_break_value - (char *) break_value)); | |
dcfdbac7 JB |
188 | } |
189 | \f | |
956ace37 JB |
190 | /* The meat - allocating, freeing, and relocating blocs. */ |
191 | ||
192 | /* These structures are allocated in the malloc arena. | |
193 | The linked list is kept in order of increasing '.data' members. | |
194 | The data blocks abut each other; if b->next is non-nil, then | |
195 | b->data + b->size == b->next->data. */ | |
dcfdbac7 JB |
196 | typedef struct bp |
197 | { | |
198 | struct bp *next; | |
199 | struct bp *prev; | |
200 | POINTER *variable; | |
201 | POINTER data; | |
202 | SIZE size; | |
203 | } *bloc_ptr; | |
204 | ||
205 | #define NIL_BLOC ((bloc_ptr) 0) | |
206 | #define BLOC_PTR_SIZE (sizeof (struct bp)) | |
207 | ||
208 | /* Head and tail of the list of relocatable blocs. */ | |
209 | static bloc_ptr first_bloc, last_bloc; | |
210 | ||
956ace37 | 211 | /* Find the bloc referenced by the address in PTR. Returns a pointer |
dcfdbac7 JB |
212 | to that block. */ |
213 | ||
214 | static bloc_ptr | |
215 | find_bloc (ptr) | |
216 | POINTER *ptr; | |
217 | { | |
218 | register bloc_ptr p = first_bloc; | |
219 | ||
220 | while (p != NIL_BLOC) | |
221 | { | |
222 | if (p->variable == ptr && p->data == *ptr) | |
223 | return p; | |
224 | ||
225 | p = p->next; | |
226 | } | |
227 | ||
228 | return p; | |
229 | } | |
230 | ||
231 | /* Allocate a bloc of SIZE bytes and append it to the chain of blocs. | |
98b7fe02 JB |
232 | Returns a pointer to the new bloc, or zero if we couldn't allocate |
233 | memory for the new block. */ | |
dcfdbac7 JB |
234 | |
235 | static bloc_ptr | |
236 | get_bloc (size) | |
237 | SIZE size; | |
238 | { | |
98b7fe02 JB |
239 | register bloc_ptr new_bloc; |
240 | ||
241 | if (! (new_bloc = (bloc_ptr) malloc (BLOC_PTR_SIZE)) | |
242 | || ! (new_bloc->data = get_more_space (size))) | |
243 | { | |
244 | if (new_bloc) | |
245 | free (new_bloc); | |
246 | ||
247 | return 0; | |
248 | } | |
dcfdbac7 | 249 | |
dcfdbac7 JB |
250 | new_bloc->size = size; |
251 | new_bloc->next = NIL_BLOC; | |
8c7f1e35 | 252 | new_bloc->variable = (POINTER *) NIL; |
dcfdbac7 JB |
253 | |
254 | if (first_bloc) | |
255 | { | |
256 | new_bloc->prev = last_bloc; | |
257 | last_bloc->next = new_bloc; | |
258 | last_bloc = new_bloc; | |
259 | } | |
260 | else | |
261 | { | |
262 | first_bloc = last_bloc = new_bloc; | |
263 | new_bloc->prev = NIL_BLOC; | |
264 | } | |
265 | ||
266 | return new_bloc; | |
267 | } | |
268 | ||
269 | /* Relocate all blocs from BLOC on upward in the list to the zone | |
270 | indicated by ADDRESS. Direction of relocation is determined by | |
271 | the position of ADDRESS relative to BLOC->data. | |
272 | ||
ad3bb3d2 JB |
273 | If BLOC is NIL_BLOC, nothing is done. |
274 | ||
dcfdbac7 JB |
275 | Note that ordering of blocs is not affected by this function. */ |
276 | ||
277 | static void | |
278 | relocate_some_blocs (bloc, address) | |
279 | bloc_ptr bloc; | |
280 | POINTER address; | |
281 | { | |
ad3bb3d2 | 282 | if (bloc != NIL_BLOC) |
dcfdbac7 | 283 | { |
ad3bb3d2 JB |
284 | register SIZE offset = address - bloc->data; |
285 | register SIZE data_size = 0; | |
286 | register bloc_ptr b; | |
287 | ||
288 | for (b = bloc; b != NIL_BLOC; b = b->next) | |
289 | { | |
290 | data_size += b->size; | |
291 | b->data += offset; | |
292 | *b->variable = b->data; | |
293 | } | |
dcfdbac7 | 294 | |
ad3bb3d2 JB |
295 | safe_bcopy (address - offset, address, data_size); |
296 | } | |
dcfdbac7 JB |
297 | } |
298 | ||
ad3bb3d2 | 299 | |
dcfdbac7 JB |
300 | /* Free BLOC from the chain of blocs, relocating any blocs above it |
301 | and returning BLOC->size bytes to the free area. */ | |
302 | ||
303 | static void | |
304 | free_bloc (bloc) | |
305 | bloc_ptr bloc; | |
306 | { | |
307 | if (bloc == first_bloc && bloc == last_bloc) | |
308 | { | |
309 | first_bloc = last_bloc = NIL_BLOC; | |
310 | } | |
311 | else if (bloc == last_bloc) | |
312 | { | |
313 | last_bloc = bloc->prev; | |
314 | last_bloc->next = NIL_BLOC; | |
315 | } | |
316 | else if (bloc == first_bloc) | |
317 | { | |
318 | first_bloc = bloc->next; | |
319 | first_bloc->prev = NIL_BLOC; | |
dcfdbac7 JB |
320 | } |
321 | else | |
322 | { | |
323 | bloc->next->prev = bloc->prev; | |
324 | bloc->prev->next = bloc->next; | |
dcfdbac7 JB |
325 | } |
326 | ||
ad3bb3d2 | 327 | relocate_some_blocs (bloc->next, bloc->data); |
dcfdbac7 JB |
328 | relinquish (bloc->size); |
329 | free (bloc); | |
330 | } | |
331 | \f | |
956ace37 JB |
332 | /* Interface routines. */ |
333 | ||
dcfdbac7 JB |
334 | static int use_relocatable_buffers; |
335 | ||
98b7fe02 | 336 | /* Obtain SIZE bytes of storage from the free pool, or the system, as |
2c46d29f | 337 | necessary. If relocatable blocs are in use, this means relocating |
98b7fe02 JB |
338 | them. This function gets plugged into the GNU malloc's __morecore |
339 | hook. | |
340 | ||
7516b7d5 RS |
341 | We provide hysteresis, never relocating by less than extra_bytes. |
342 | ||
98b7fe02 JB |
343 | If we're out of memory, we should return zero, to imitate the other |
344 | __morecore hook values - in particular, __default_morecore in the | |
345 | GNU malloc package. */ | |
dcfdbac7 JB |
346 | |
347 | POINTER | |
348 | r_alloc_sbrk (size) | |
349 | long size; | |
350 | { | |
7516b7d5 RS |
351 | /* This is the first address not currently available for the heap. */ |
352 | POINTER top; | |
353 | /* Amount of empty space below that. */ | |
89ccd65a RS |
354 | /* It is not correct to use SIZE here, because that is usually unsigned. |
355 | ptrdiff_t would be okay, but is not always available. | |
356 | `long' will work in all cases, in practice. */ | |
357 | long already_available; | |
dcfdbac7 JB |
358 | POINTER ptr; |
359 | ||
360 | if (! use_relocatable_buffers) | |
bbc60227 | 361 | return (*real_morecore) (size); |
dcfdbac7 | 362 | |
7516b7d5 RS |
363 | top = first_bloc ? first_bloc->data : page_break_value; |
364 | already_available = (char *) top - (char *) virtual_break_value; | |
365 | ||
366 | /* Do we not have enough gap already? */ | |
367 | if (size > 0 && already_available < size) | |
dcfdbac7 | 368 | { |
7516b7d5 RS |
369 | /* Get what we need, plus some extra so we can come here less often. */ |
370 | SIZE get = size - already_available + extra_bytes; | |
371 | ||
372 | if (! obtain (get)) | |
98b7fe02 JB |
373 | return 0; |
374 | ||
dcfdbac7 | 375 | if (first_bloc) |
ad3bb3d2 | 376 | relocate_some_blocs (first_bloc, first_bloc->data + get); |
956ace37 | 377 | |
ad3bb3d2 JB |
378 | /* Zero out the space we just allocated, to help catch bugs |
379 | quickly. */ | |
380 | bzero (virtual_break_value, get); | |
dcfdbac7 | 381 | } |
7516b7d5 RS |
382 | /* Can we keep extra_bytes of gap while freeing at least extra_bytes? */ |
383 | else if (size < 0 && already_available - size > 2 * extra_bytes) | |
dcfdbac7 | 384 | { |
7516b7d5 RS |
385 | /* Ok, do so. This is how many to free. */ |
386 | SIZE give_back = already_available - size - extra_bytes; | |
387 | ||
dcfdbac7 | 388 | if (first_bloc) |
7516b7d5 RS |
389 | relocate_some_blocs (first_bloc, first_bloc->data - give_back); |
390 | relinquish (give_back); | |
dcfdbac7 JB |
391 | } |
392 | ||
393 | ptr = virtual_break_value; | |
394 | virtual_break_value += size; | |
7516b7d5 | 395 | |
dcfdbac7 JB |
396 | return ptr; |
397 | } | |
398 | ||
399 | /* Allocate a relocatable bloc of storage of size SIZE. A pointer to | |
400 | the data is returned in *PTR. PTR is thus the address of some variable | |
98b7fe02 JB |
401 | which will use the data area. |
402 | ||
403 | If we can't allocate the necessary memory, set *PTR to zero, and | |
404 | return zero. */ | |
dcfdbac7 JB |
405 | |
406 | POINTER | |
407 | r_alloc (ptr, size) | |
408 | POINTER *ptr; | |
409 | SIZE size; | |
410 | { | |
411 | register bloc_ptr new_bloc; | |
412 | ||
2c46d29f RS |
413 | if (! r_alloc_initialized) |
414 | r_alloc_init (); | |
415 | ||
dcfdbac7 | 416 | new_bloc = get_bloc (size); |
98b7fe02 JB |
417 | if (new_bloc) |
418 | { | |
419 | new_bloc->variable = ptr; | |
420 | *ptr = new_bloc->data; | |
421 | } | |
422 | else | |
423 | *ptr = 0; | |
dcfdbac7 JB |
424 | |
425 | return *ptr; | |
426 | } | |
427 | ||
2c46d29f RS |
428 | /* Free a bloc of relocatable storage whose data is pointed to by PTR. |
429 | Store 0 in *PTR to show there's no block allocated. */ | |
dcfdbac7 JB |
430 | |
431 | void | |
432 | r_alloc_free (ptr) | |
433 | register POINTER *ptr; | |
434 | { | |
435 | register bloc_ptr dead_bloc; | |
436 | ||
dcfdbac7 JB |
437 | dead_bloc = find_bloc (ptr); |
438 | if (dead_bloc == NIL_BLOC) | |
439 | abort (); | |
440 | ||
441 | free_bloc (dead_bloc); | |
2c46d29f | 442 | *ptr = 0; |
dcfdbac7 JB |
443 | } |
444 | ||
16a5c729 | 445 | /* Given a pointer at address PTR to relocatable data, resize it to SIZE. |
98b7fe02 JB |
446 | Do this by shifting all blocks above this one up in memory, unless |
447 | SIZE is less than or equal to the current bloc size, in which case | |
448 | do nothing. | |
dcfdbac7 | 449 | |
98b7fe02 JB |
450 | Change *PTR to reflect the new bloc, and return this value. |
451 | ||
452 | If more memory cannot be allocated, then leave *PTR unchanged, and | |
453 | return zero. */ | |
dcfdbac7 JB |
454 | |
455 | POINTER | |
456 | r_re_alloc (ptr, size) | |
457 | POINTER *ptr; | |
458 | SIZE size; | |
459 | { | |
16a5c729 | 460 | register bloc_ptr bloc; |
dcfdbac7 | 461 | |
16a5c729 JB |
462 | bloc = find_bloc (ptr); |
463 | if (bloc == NIL_BLOC) | |
dcfdbac7 JB |
464 | abort (); |
465 | ||
16a5c729 | 466 | if (size <= bloc->size) |
956ace37 | 467 | /* Wouldn't it be useful to actually resize the bloc here? */ |
dcfdbac7 JB |
468 | return *ptr; |
469 | ||
98b7fe02 JB |
470 | if (! obtain (size - bloc->size)) |
471 | return 0; | |
472 | ||
16a5c729 | 473 | relocate_some_blocs (bloc->next, bloc->data + size); |
dcfdbac7 | 474 | |
16a5c729 JB |
475 | /* Zero out the new space in the bloc, to help catch bugs faster. */ |
476 | bzero (bloc->data + bloc->size, size - bloc->size); | |
0abf54e3 | 477 | |
16a5c729 JB |
478 | /* Indicate that this block has a new size. */ |
479 | bloc->size = size; | |
dcfdbac7 JB |
480 | |
481 | return *ptr; | |
482 | } | |
483 | \f | |
484 | /* The hook `malloc' uses for the function which gets more space | |
485 | from the system. */ | |
486 | extern POINTER (*__morecore) (); | |
487 | ||
488 | /* Intialize various things for memory allocation. */ | |
489 | ||
2c46d29f RS |
490 | static void |
491 | r_alloc_init () | |
dcfdbac7 | 492 | { |
2c46d29f | 493 | if (r_alloc_initialized) |
dcfdbac7 JB |
494 | return; |
495 | ||
2c46d29f | 496 | r_alloc_initialized = 1; |
bbc60227 | 497 | real_morecore = __morecore; |
dcfdbac7 | 498 | __morecore = r_alloc_sbrk; |
8c7f1e35 | 499 | |
bbc60227 | 500 | virtual_break_value = break_value = (*real_morecore) (0); |
aef4d570 | 501 | if (break_value == NIL) |
2c46d29f | 502 | abort (); |
8c7f1e35 | 503 | |
7516b7d5 RS |
504 | page_size = PAGE; |
505 | extra_bytes = ROUNDUP (50000); | |
506 | ||
dcfdbac7 | 507 | page_break_value = (POINTER) ROUNDUP (break_value); |
2c46d29f RS |
508 | /* Clear the rest of the last page; this memory is in our address space |
509 | even though it is after the sbrk value. */ | |
dcfdbac7 JB |
510 | bzero (break_value, (page_break_value - break_value)); |
511 | use_relocatable_buffers = 1; | |
2c46d29f | 512 | } |