/vendor/gc/headers.c

  1/* 
  2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
  3 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  4 * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
  5 *
  6 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
  7 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
  8 *
  9 * Permission is hereby granted to use or copy this program
 10 * for any purpose,  provided the above notices are retained on all copies.
 11 * Permission to modify the code and to distribute modified code is granted,
 12 * provided the above notices are retained, and a notice that the code was
 13 * modified is included with the above copyright notice.
 14 */
 15 
 16/*
 17 * This implements:
 18 * 1. allocation of heap block headers
 19 * 2. A map from addresses to heap block addresses to heap block headers
 20 *
 21 * Access speed is crucial.  We implement an index structure based on a 2
 22 * level tree.
 23 */
 24 
 25# include "private/gc_priv.h"
 26
 27bottom_index * GC_all_bottom_indices = 0;
 28				/* Pointer to first (lowest addr) */
 29				/* bottom_index.		  */
 30
 31bottom_index * GC_all_bottom_indices_end = 0;
 32				/* Pointer to last (highest addr) */
 33				/* bottom_index.		  */
 34 
 35/* Non-macro version of header location routine */
 36hdr * GC_find_header(ptr_t h)
 37{
 38#   ifdef HASH_TL
 39	hdr * result;
 40	GET_HDR(h, result);
 41	return(result);
 42#   else
 43	return(HDR_INNER(h));
 44#   endif
 45}
 46
 47/* Handle a header cache miss.  Returns a pointer to the	*/
 48/* header corresponding to p, if p can possibly be a valid	*/
 49/* object pointer, and 0 otherwise.				*/
 50/* GUARANTEED to return 0 for a pointer past the first page	*/
 51/* of an object unless both GC_all_interior_pointers is set	*/
 52/* and p is in fact a valid object pointer.			*/
 53#ifdef PRINT_BLACK_LIST
 54  hdr * GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce, ptr_t source)
 55#else
 56  hdr * GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce)
 57#endif
 58{
 59  hdr *hhdr;
 60  HC_MISS();
 61  GET_HDR(p, hhdr);
 62  if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
 63    if (GC_all_interior_pointers) {
 64      if (hhdr != 0) {
 65	ptr_t current = p;
 66	    
 67	current = (ptr_t)HBLKPTR(current);
 68	do {
 69	    current = current - HBLKSIZE*(word)hhdr;
 70	    hhdr = HDR(current);
 71	} while(IS_FORWARDING_ADDR_OR_NIL(hhdr));
 72	/* current points to near the start of the large object */
 73	if (hhdr -> hb_flags & IGNORE_OFF_PAGE
 74	    || HBLK_IS_FREE(hhdr))
 75	    return 0;
 76	if (p - current >= (ptrdiff_t)(hhdr->hb_sz)) {
 77	    GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
 78	    /* Pointer past the end of the block */
 79	    return 0;
 80	}
 81      } else {
 82	GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
 83      }
 84      return hhdr;
 85      /* Pointers past the first page are probably too rare	*/
 86      /* to add them to the cache.  We don't.			*/
 87      /* And correctness relies on the fact that we don't.	*/
 88    } else {
 89      if (hhdr == 0) {
 90	GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
 91      }
 92      return 0;
 93    }
 94  } else {
 95    if (HBLK_IS_FREE(hhdr)) {
 96      GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
 97      return 0;
 98    } else {
 99      hce -> block_addr = (word)(p) >> LOG_HBLKSIZE;
100      hce -> hce_hdr = hhdr; 
101      return hhdr;
102    }
103  } 
104}
105 
106/* Routines to dynamically allocate collector data structures that will */
107/* never be freed.							 */
108 
109static ptr_t scratch_free_ptr = 0;
110 
111/* GC_scratch_last_end_ptr is end point of last obtained scratch area.  */
112/* GC_scratch_end_ptr is end point of current scratch area.		*/
113 
114ptr_t GC_scratch_alloc(size_t bytes)
115{
116    register ptr_t result = scratch_free_ptr;
117
118    bytes += GRANULE_BYTES-1;
119    bytes &= ~(GRANULE_BYTES-1);
120    scratch_free_ptr += bytes;
121    if (scratch_free_ptr <= GC_scratch_end_ptr) {
122        return(result);
123    }
124    {
125        word bytes_to_get = MINHINCR * HBLKSIZE;
126         
127        if (bytes_to_get <= bytes) {
128          /* Undo the damage, and get memory directly */
129	    bytes_to_get = bytes;
130#	    ifdef USE_MMAP
131		bytes_to_get += GC_page_size - 1;
132		bytes_to_get &= ~(GC_page_size - 1);
133#	    endif
134   	    result = (ptr_t)GET_MEM(bytes_to_get);
135	    GC_add_to_our_memory(result, bytes_to_get);
136            scratch_free_ptr -= bytes;
137	    GC_scratch_last_end_ptr = result + bytes;
138            return(result);
139        }
140        result = (ptr_t)GET_MEM(bytes_to_get);
141        GC_add_to_our_memory(result, bytes_to_get);
142        if (result == 0) {
143	    if (GC_print_stats)
144                GC_printf("Out of memory - trying to allocate less\n");
145            scratch_free_ptr -= bytes;
146	    bytes_to_get = bytes;
147#	    ifdef USE_MMAP
148		bytes_to_get += GC_page_size - 1;
149		bytes_to_get &= ~(GC_page_size - 1);
150#	    endif
151            result = (ptr_t)GET_MEM(bytes_to_get);
152            GC_add_to_our_memory(result, bytes_to_get);
153	    return result;
154        }
155        scratch_free_ptr = result;
156        GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
157        GC_scratch_last_end_ptr = GC_scratch_end_ptr;
158        return(GC_scratch_alloc(bytes));
159    }
160}
161
162static hdr * hdr_free_list = 0;
163
164/* Return an uninitialized header */
165static hdr * alloc_hdr(void)
166{
167    register hdr * result;
168    
169    if (hdr_free_list == 0) {
170        result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
171    } else {
172        result = hdr_free_list;
173        hdr_free_list = (hdr *) (result -> hb_next);
174    }
175    return(result);
176}
177
178static void free_hdr(hdr * hhdr)
179{
180    hhdr -> hb_next = (struct hblk *) hdr_free_list;
181    hdr_free_list = hhdr;
182}
183
184#ifdef USE_HDR_CACHE
185  word GC_hdr_cache_hits = 0;
186  word GC_hdr_cache_misses = 0;
187#endif
188 
189void GC_init_headers(void)
190{
191    register unsigned i;
192    
193    GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
194    BZERO(GC_all_nils, sizeof(bottom_index));
195    for (i = 0; i < TOP_SZ; i++) {
196        GC_top_index[i] = GC_all_nils;
197    }
198}
199
200/* Make sure that there is a bottom level index block for address addr  */
201/* Return FALSE on failure.						*/
202static GC_bool get_index(word addr)
203{
204    word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
205    bottom_index * r;
206    bottom_index * p;
207    bottom_index ** prev;
208    bottom_index *pi;
209    
210#   ifdef HASH_TL
211      word i = TL_HASH(hi);
212      bottom_index * old;
213      
214      old = p = GC_top_index[i];
215      while(p != GC_all_nils) {
216          if (p -> key == hi) return(TRUE);
217          p = p -> hash_link;
218      }
219      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
220      if (r == 0) return(FALSE);
221      BZERO(r, sizeof (bottom_index));
222      r -> hash_link = old;
223      GC_top_index[i] = r;
224#   else
225      if (GC_top_index[hi] != GC_all_nils) return(TRUE);
226      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
227      if (r == 0) return(FALSE);
228      GC_top_index[hi] = r;
229      BZERO(r, sizeof (bottom_index));
230#   endif
231    r -> key = hi;
232    /* Add it to the list of bottom indices */
233      prev = &GC_all_bottom_indices;  	/* pointer to p */
234      pi = 0;				/* bottom_index preceding p */
235      while ((p = *prev) != 0 && p -> key < hi) {
236	pi = p;
237	prev = &(p -> asc_link);
238      }
239      r -> desc_link = pi;
240      if (0 == p) {
241	GC_all_bottom_indices_end = r;
242      } else {
243	p -> desc_link = r;
244      }
245      r -> asc_link = p;
246      *prev = r;
247    return(TRUE);
248}
249
250/* Install a header for block h.	*/
251/* The header is uninitialized.	  	*/
252/* Returns the header or 0 on failure.	*/
253struct hblkhdr * GC_install_header(struct hblk *h)
254{
255    hdr * result;
256    
257    if (!get_index((word) h)) return(0);
258    result = alloc_hdr();
259    SET_HDR(h, result);
260#   ifdef USE_MUNMAP
261	result -> hb_last_reclaimed = (unsigned short)GC_gc_no;
262#   endif
263    return(result);
264}
265
266/* Set up forwarding counts for block h of size sz */
267GC_bool GC_install_counts(struct hblk *h, size_t sz/* bytes */)
268{
269    struct hblk * hbp;
270    word i;
271    
272    for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
273        if (!get_index((word) hbp)) return(FALSE);
274    }
275    if (!get_index((word)h + sz - 1)) return(FALSE);
276    for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
277        i = HBLK_PTR_DIFF(hbp, h);
278        SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
279    }
280    return(TRUE);
281}
282
283/* Remove the header for block h */
284void GC_remove_header(struct hblk *h)
285{
286    hdr ** ha;
287    
288    GET_HDR_ADDR(h, ha);
289    free_hdr(*ha);
290    *ha = 0;
291}
292
293/* Remove forwarding counts for h */
294void GC_remove_counts(struct hblk *h, size_t sz/* bytes */)
295{
296    register struct hblk * hbp;
297    
298    for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
299        SET_HDR(hbp, 0);
300    }
301}
302
303/* Apply fn to all allocated blocks */
304/*VARARGS1*/
305void GC_apply_to_all_blocks(void (*fn)(struct hblk *h, word client_data),
306			    word client_data)
307{
308    signed_word j;
309    bottom_index * index_p;
310    
311    for (index_p = GC_all_bottom_indices; index_p != 0;
312         index_p = index_p -> asc_link) {
313        for (j = BOTTOM_SZ-1; j >= 0;) {
314            if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
315                if (!HBLK_IS_FREE(index_p->index[j])) {
316                    (*fn)(((struct hblk *)
317                  	      (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
318                  	       << LOG_HBLKSIZE)),
319                          client_data);
320                }
321                j--;
322             } else if (index_p->index[j] == 0) {
323                j--;
324             } else {
325                j -= (signed_word)(index_p->index[j]);
326             }
327         }
328     }
329}
330
331/* Get the next valid block whose address is at least h	*/
332/* Return 0 if there is none.				*/
333struct hblk * GC_next_used_block(struct hblk *h)
334{
335    register bottom_index * bi;
336    register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
337    
338    GET_BI(h, bi);
339    if (bi == GC_all_nils) {
340        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
341        bi = GC_all_bottom_indices;
342        while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
343        j = 0;
344    }
345    while(bi != 0) {
346        while (j < BOTTOM_SZ) {
347	    hdr * hhdr = bi -> index[j];
348            if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
349                j++;
350            } else {
351                if (!HBLK_IS_FREE(hhdr)) {
352                    return((struct hblk *)
353                  	      (((bi -> key << LOG_BOTTOM_SZ) + j)
354                  	       << LOG_HBLKSIZE));
355                } else {
356                    j += divHBLKSZ(hhdr -> hb_sz);
357                }
358            }
359        }
360        j = 0;
361        bi = bi -> asc_link;
362    }
363    return(0);
364}
365
366/* Get the last (highest address) block whose address is 	*/
367/* at most h.  Return 0 if there is none.			*/
368/* Unlike the above, this may return a free block.		*/
369struct hblk * GC_prev_block(struct hblk *h)
370{
371    register bottom_index * bi;
372    register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
373    
374    GET_BI(h, bi);
375    if (bi == GC_all_nils) {
376        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
377        bi = GC_all_bottom_indices_end;
378        while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
379        j = BOTTOM_SZ - 1;
380    }
381    while(bi != 0) {
382        while (j >= 0) {
383	    hdr * hhdr = bi -> index[j];
384	    if (0 == hhdr) {
385		--j;
386            } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
387                j -= (signed_word)hhdr;
388            } else {
389                return((struct hblk *)
390                          (((bi -> key << LOG_BOTTOM_SZ) + j)
391                  	       << LOG_HBLKSIZE));
392            }
393        }
394        j = BOTTOM_SZ - 1;
395        bi = bi -> desc_link;
396    }
397    return(0);
398}