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-rw-r--r--boehm_gc/headers.c394
1 files changed, 394 insertions, 0 deletions
diff --git a/boehm_gc/headers.c b/boehm_gc/headers.c
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+/*
+ * 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);
+ scratch_free_ptr -= bytes;
+ GC_scratch_last_end_ptr = result + bytes;
+ return(result);
+ }
+ result = (ptr_t)GET_MEM(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
+ return((ptr_t)GET_MEM(bytes_to_get));
+ }
+ 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);
+}
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