/vendor/gc/headers.c
http://github.com/feyeleanor/RubyGoLightly · C · 398 lines · 301 code · 37 blank · 60 comment · 80 complexity · fc6df30d777bee1a34293529d8c02666 MD5 · raw file
- /*
- * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
- * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
- * Copyright (c) 1996 by Silicon Graphics. All rights reserved.
- *
- * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
- * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
- *
- * Permission is hereby granted to use or copy this program
- * for any purpose, provided the above notices are retained on all copies.
- * Permission to modify the code and to distribute modified code is granted,
- * provided the above notices are retained, and a notice that the code was
- * modified is included with the above copyright notice.
- */
-
- /*
- * This implements:
- * 1. allocation of heap block headers
- * 2. A map from addresses to heap block addresses to heap block headers
- *
- * Access speed is crucial. We implement an index structure based on a 2
- * level tree.
- */
-
- # include "private/gc_priv.h"
- bottom_index * GC_all_bottom_indices = 0;
- /* Pointer to first (lowest addr) */
- /* bottom_index. */
- bottom_index * GC_all_bottom_indices_end = 0;
- /* Pointer to last (highest addr) */
- /* bottom_index. */
-
- /* Non-macro version of header location routine */
- hdr * GC_find_header(ptr_t h)
- {
- # ifdef HASH_TL
- hdr * result;
- GET_HDR(h, result);
- return(result);
- # else
- return(HDR_INNER(h));
- # endif
- }
- /* Handle a header cache miss. Returns a pointer to the */
- /* header corresponding to p, if p can possibly be a valid */
- /* object pointer, and 0 otherwise. */
- /* GUARANTEED to return 0 for a pointer past the first page */
- /* of an object unless both GC_all_interior_pointers is set */
- /* and p is in fact a valid object pointer. */
- #ifdef PRINT_BLACK_LIST
- hdr * GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce, ptr_t source)
- #else
- hdr * GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce)
- #endif
- {
- hdr *hhdr;
- HC_MISS();
- GET_HDR(p, hhdr);
- if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
- if (GC_all_interior_pointers) {
- if (hhdr != 0) {
- ptr_t current = p;
-
- current = (ptr_t)HBLKPTR(current);
- do {
- current = current - HBLKSIZE*(word)hhdr;
- hhdr = HDR(current);
- } while(IS_FORWARDING_ADDR_OR_NIL(hhdr));
- /* current points to near the start of the large object */
- if (hhdr -> hb_flags & IGNORE_OFF_PAGE
- || HBLK_IS_FREE(hhdr))
- return 0;
- if (p - current >= (ptrdiff_t)(hhdr->hb_sz)) {
- GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
- /* Pointer past the end of the block */
- return 0;
- }
- } else {
- GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
- }
- return hhdr;
- /* Pointers past the first page are probably too rare */
- /* to add them to the cache. We don't. */
- /* And correctness relies on the fact that we don't. */
- } else {
- if (hhdr == 0) {
- GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
- }
- return 0;
- }
- } else {
- if (HBLK_IS_FREE(hhdr)) {
- GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
- return 0;
- } else {
- hce -> block_addr = (word)(p) >> LOG_HBLKSIZE;
- hce -> hce_hdr = hhdr;
- return hhdr;
- }
- }
- }
-
- /* Routines to dynamically allocate collector data structures that will */
- /* never be freed. */
-
- static ptr_t scratch_free_ptr = 0;
-
- /* GC_scratch_last_end_ptr is end point of last obtained scratch area. */
- /* GC_scratch_end_ptr is end point of current scratch area. */
-
- ptr_t GC_scratch_alloc(size_t bytes)
- {
- register ptr_t result = scratch_free_ptr;
- bytes += GRANULE_BYTES-1;
- bytes &= ~(GRANULE_BYTES-1);
- scratch_free_ptr += bytes;
- if (scratch_free_ptr <= GC_scratch_end_ptr) {
- return(result);
- }
- {
- word bytes_to_get = MINHINCR * HBLKSIZE;
-
- if (bytes_to_get <= bytes) {
- /* Undo the damage, and get memory directly */
- bytes_to_get = bytes;
- # ifdef USE_MMAP
- bytes_to_get += GC_page_size - 1;
- bytes_to_get &= ~(GC_page_size - 1);
- # endif
- result = (ptr_t)GET_MEM(bytes_to_get);
- GC_add_to_our_memory(result, bytes_to_get);
- scratch_free_ptr -= bytes;
- GC_scratch_last_end_ptr = result + bytes;
- return(result);
- }
- result = (ptr_t)GET_MEM(bytes_to_get);
- GC_add_to_our_memory(result, bytes_to_get);
- if (result == 0) {
- if (GC_print_stats)
- GC_printf("Out of memory - trying to allocate less\n");
- scratch_free_ptr -= bytes;
- bytes_to_get = bytes;
- # ifdef USE_MMAP
- bytes_to_get += GC_page_size - 1;
- bytes_to_get &= ~(GC_page_size - 1);
- # endif
- result = (ptr_t)GET_MEM(bytes_to_get);
- GC_add_to_our_memory(result, bytes_to_get);
- return result;
- }
- scratch_free_ptr = result;
- GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
- GC_scratch_last_end_ptr = GC_scratch_end_ptr;
- return(GC_scratch_alloc(bytes));
- }
- }
- static hdr * hdr_free_list = 0;
- /* Return an uninitialized header */
- static hdr * alloc_hdr(void)
- {
- register hdr * result;
-
- if (hdr_free_list == 0) {
- result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
- } else {
- result = hdr_free_list;
- hdr_free_list = (hdr *) (result -> hb_next);
- }
- return(result);
- }
- static void free_hdr(hdr * hhdr)
- {
- hhdr -> hb_next = (struct hblk *) hdr_free_list;
- hdr_free_list = hhdr;
- }
- #ifdef USE_HDR_CACHE
- word GC_hdr_cache_hits = 0;
- word GC_hdr_cache_misses = 0;
- #endif
-
- void GC_init_headers(void)
- {
- register unsigned i;
-
- GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
- BZERO(GC_all_nils, sizeof(bottom_index));
- for (i = 0; i < TOP_SZ; i++) {
- GC_top_index[i] = GC_all_nils;
- }
- }
- /* Make sure that there is a bottom level index block for address addr */
- /* Return FALSE on failure. */
- static GC_bool get_index(word addr)
- {
- word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
- bottom_index * r;
- bottom_index * p;
- bottom_index ** prev;
- bottom_index *pi;
-
- # ifdef HASH_TL
- word i = TL_HASH(hi);
- bottom_index * old;
-
- old = p = GC_top_index[i];
- while(p != GC_all_nils) {
- if (p -> key == hi) return(TRUE);
- p = p -> hash_link;
- }
- r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
- if (r == 0) return(FALSE);
- BZERO(r, sizeof (bottom_index));
- r -> hash_link = old;
- GC_top_index[i] = r;
- # else
- if (GC_top_index[hi] != GC_all_nils) return(TRUE);
- r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
- if (r == 0) return(FALSE);
- GC_top_index[hi] = r;
- BZERO(r, sizeof (bottom_index));
- # endif
- r -> key = hi;
- /* Add it to the list of bottom indices */
- prev = &GC_all_bottom_indices; /* pointer to p */
- pi = 0; /* bottom_index preceding p */
- while ((p = *prev) != 0 && p -> key < hi) {
- pi = p;
- prev = &(p -> asc_link);
- }
- r -> desc_link = pi;
- if (0 == p) {
- GC_all_bottom_indices_end = r;
- } else {
- p -> desc_link = r;
- }
- r -> asc_link = p;
- *prev = r;
- return(TRUE);
- }
- /* Install a header for block h. */
- /* The header is uninitialized. */
- /* Returns the header or 0 on failure. */
- struct hblkhdr * GC_install_header(struct hblk *h)
- {
- hdr * result;
-
- if (!get_index((word) h)) return(0);
- result = alloc_hdr();
- SET_HDR(h, result);
- # ifdef USE_MUNMAP
- result -> hb_last_reclaimed = (unsigned short)GC_gc_no;
- # endif
- return(result);
- }
- /* Set up forwarding counts for block h of size sz */
- GC_bool GC_install_counts(struct hblk *h, size_t sz/* bytes */)
- {
- struct hblk * hbp;
- word i;
-
- for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
- if (!get_index((word) hbp)) return(FALSE);
- }
- if (!get_index((word)h + sz - 1)) return(FALSE);
- for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
- i = HBLK_PTR_DIFF(hbp, h);
- SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
- }
- return(TRUE);
- }
- /* Remove the header for block h */
- void GC_remove_header(struct hblk *h)
- {
- hdr ** ha;
-
- GET_HDR_ADDR(h, ha);
- free_hdr(*ha);
- *ha = 0;
- }
- /* Remove forwarding counts for h */
- void GC_remove_counts(struct hblk *h, size_t sz/* bytes */)
- {
- register struct hblk * hbp;
-
- for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
- SET_HDR(hbp, 0);
- }
- }
- /* Apply fn to all allocated blocks */
- /*VARARGS1*/
- void GC_apply_to_all_blocks(void (*fn)(struct hblk *h, word client_data),
- word client_data)
- {
- signed_word j;
- bottom_index * index_p;
-
- for (index_p = GC_all_bottom_indices; index_p != 0;
- index_p = index_p -> asc_link) {
- for (j = BOTTOM_SZ-1; j >= 0;) {
- if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
- if (!HBLK_IS_FREE(index_p->index[j])) {
- (*fn)(((struct hblk *)
- (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
- << LOG_HBLKSIZE)),
- client_data);
- }
- j--;
- } else if (index_p->index[j] == 0) {
- j--;
- } else {
- j -= (signed_word)(index_p->index[j]);
- }
- }
- }
- }
- /* Get the next valid block whose address is at least h */
- /* Return 0 if there is none. */
- struct hblk * GC_next_used_block(struct hblk *h)
- {
- register bottom_index * bi;
- register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
-
- GET_BI(h, bi);
- if (bi == GC_all_nils) {
- register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
- bi = GC_all_bottom_indices;
- while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
- j = 0;
- }
- while(bi != 0) {
- while (j < BOTTOM_SZ) {
- hdr * hhdr = bi -> index[j];
- if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
- j++;
- } else {
- if (!HBLK_IS_FREE(hhdr)) {
- return((struct hblk *)
- (((bi -> key << LOG_BOTTOM_SZ) + j)
- << LOG_HBLKSIZE));
- } else {
- j += divHBLKSZ(hhdr -> hb_sz);
- }
- }
- }
- j = 0;
- bi = bi -> asc_link;
- }
- return(0);
- }
- /* Get the last (highest address) block whose address is */
- /* at most h. Return 0 if there is none. */
- /* Unlike the above, this may return a free block. */
- struct hblk * GC_prev_block(struct hblk *h)
- {
- register bottom_index * bi;
- register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
-
- GET_BI(h, bi);
- if (bi == GC_all_nils) {
- register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
- bi = GC_all_bottom_indices_end;
- while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
- j = BOTTOM_SZ - 1;
- }
- while(bi != 0) {
- while (j >= 0) {
- hdr * hhdr = bi -> index[j];
- if (0 == hhdr) {
- --j;
- } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
- j -= (signed_word)hhdr;
- } else {
- return((struct hblk *)
- (((bi -> key << LOG_BOTTOM_SZ) + j)
- << LOG_HBLKSIZE));
- }
- }
- j = BOTTOM_SZ - 1;
- bi = bi -> desc_link;
- }
- return(0);
- }