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This commit is contained in:
Akinori Ito
351
gc/headers.c
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351
gc/headers.c
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/*
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* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
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* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
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* Copyright (c) 1996 by Silicon Graphics. All rights reserved.
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*
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* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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*
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* Permission is hereby granted to use or copy this program
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* for any purpose, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is granted,
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* provided the above notices are retained, and a notice that the code was
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* modified is included with the above copyright notice.
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*/
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/*
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* This implements:
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* 1. allocation of heap block headers
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* 2. A map from addresses to heap block addresses to heap block headers
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*
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* Access speed is crucial. We implement an index structure based on a 2
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* level tree.
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*/
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# include "gc_priv.h"
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bottom_index * GC_all_bottom_indices = 0;
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/* Pointer to first (lowest addr) */
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/* bottom_index. */
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bottom_index * GC_all_bottom_indices_end = 0;
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/* Pointer to last (highest addr) */
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/* bottom_index. */
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/* Non-macro version of header location routine */
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hdr * GC_find_header(h)
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ptr_t h;
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{
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# ifdef HASH_TL
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register hdr * result;
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GET_HDR(h, result);
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return(result);
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# else
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return(HDR_INNER(h));
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# endif
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}
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/* Routines to dynamically allocate collector data structures that will */
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/* never be freed. */
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static ptr_t scratch_free_ptr = 0;
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ptr_t GC_scratch_end_ptr = 0;
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ptr_t GC_scratch_last_end_ptr = 0;
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/* End point of last obtained scratch area */
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ptr_t GC_scratch_alloc(bytes)
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register word bytes;
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{
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register ptr_t result = scratch_free_ptr;
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# ifdef ALIGN_DOUBLE
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# define GRANULARITY (2 * sizeof(word))
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# else
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# define GRANULARITY sizeof(word)
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# endif
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bytes += GRANULARITY-1;
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bytes &= ~(GRANULARITY-1);
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scratch_free_ptr += bytes;
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if (scratch_free_ptr <= GC_scratch_end_ptr) {
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return(result);
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}
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{
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word bytes_to_get = MINHINCR * HBLKSIZE;
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if (bytes_to_get <= bytes) {
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/* Undo the damage, and get memory directly */
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bytes_to_get = bytes;
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# ifdef USE_MMAP
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bytes_to_get += GC_page_size - 1;
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bytes_to_get &= ~(GC_page_size - 1);
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# endif
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result = (ptr_t)GET_MEM(bytes_to_get);
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scratch_free_ptr -= bytes;
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GC_scratch_last_end_ptr = result + bytes;
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return(result);
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}
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result = (ptr_t)GET_MEM(bytes_to_get);
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if (result == 0) {
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# ifdef PRINTSTATS
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GC_printf0("Out of memory - trying to allocate less\n");
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# endif
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scratch_free_ptr -= bytes;
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bytes_to_get = bytes;
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# ifdef USE_MMAP
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bytes_to_get += GC_page_size - 1;
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bytes_to_get &= ~(GC_page_size - 1);
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# endif
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return((ptr_t)GET_MEM(bytes_to_get));
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}
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scratch_free_ptr = result;
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GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
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GC_scratch_last_end_ptr = GC_scratch_end_ptr;
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return(GC_scratch_alloc(bytes));
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}
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}
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static hdr * hdr_free_list = 0;
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/* Return an uninitialized header */
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static hdr * alloc_hdr()
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{
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register hdr * result;
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if (hdr_free_list == 0) {
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result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
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} else {
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result = hdr_free_list;
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hdr_free_list = (hdr *) (result -> hb_next);
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}
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return(result);
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}
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static void free_hdr(hhdr)
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hdr * hhdr;
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{
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hhdr -> hb_next = (struct hblk *) hdr_free_list;
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hdr_free_list = hhdr;
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}
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void GC_init_headers()
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{
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register unsigned i;
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GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
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BZERO(GC_all_nils, sizeof(bottom_index));
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for (i = 0; i < TOP_SZ; i++) {
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GC_top_index[i] = GC_all_nils;
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}
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}
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/* Make sure that there is a bottom level index block for address addr */
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/* Return FALSE on failure. */
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static GC_bool get_index(addr)
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word addr;
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{
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word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
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bottom_index * r;
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bottom_index * p;
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bottom_index ** prev;
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bottom_index *pi;
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# ifdef HASH_TL
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unsigned i = TL_HASH(hi);
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bottom_index * old;
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old = p = GC_top_index[i];
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while(p != GC_all_nils) {
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if (p -> key == hi) return(TRUE);
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p = p -> hash_link;
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}
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r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
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if (r == 0) return(FALSE);
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BZERO(r, sizeof (bottom_index));
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r -> hash_link = old;
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GC_top_index[i] = r;
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# else
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if (GC_top_index[hi] != GC_all_nils) return(TRUE);
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r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
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if (r == 0) return(FALSE);
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GC_top_index[hi] = r;
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BZERO(r, sizeof (bottom_index));
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# endif
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r -> key = hi;
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/* Add it to the list of bottom indices */
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prev = &GC_all_bottom_indices; /* pointer to p */
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pi = 0; /* bottom_index preceding p */
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while ((p = *prev) != 0 && p -> key < hi) {
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pi = p;
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prev = &(p -> asc_link);
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}
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r -> desc_link = pi;
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if (0 == p) {
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GC_all_bottom_indices_end = r;
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} else {
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p -> desc_link = r;
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}
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r -> asc_link = p;
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*prev = r;
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return(TRUE);
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}
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/* Install a header for block h. */
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/* The header is uninitialized. */
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/* Returns FALSE on failure. */
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GC_bool GC_install_header(h)
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register struct hblk * h;
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{
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hdr * result;
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if (!get_index((word) h)) return(FALSE);
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result = alloc_hdr();
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SET_HDR(h, result);
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# ifdef USE_MUNMAP
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result -> hb_last_reclaimed = GC_gc_no;
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# endif
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return(result != 0);
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}
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/* Set up forwarding counts for block h of size sz */
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GC_bool GC_install_counts(h, sz)
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register struct hblk * h;
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register word sz; /* bytes */
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{
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register struct hblk * hbp;
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register int i;
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for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
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if (!get_index((word) hbp)) return(FALSE);
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}
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if (!get_index((word)h + sz - 1)) return(FALSE);
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for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
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i = HBLK_PTR_DIFF(hbp, h);
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SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
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}
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return(TRUE);
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}
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/* Remove the header for block h */
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void GC_remove_header(h)
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register struct hblk * h;
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{
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hdr ** ha;
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GET_HDR_ADDR(h, ha);
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free_hdr(*ha);
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*ha = 0;
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}
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/* Remove forwarding counts for h */
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void GC_remove_counts(h, sz)
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register struct hblk * h;
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register word sz; /* bytes */
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{
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register struct hblk * hbp;
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for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
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SET_HDR(hbp, 0);
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}
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}
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/* Apply fn to all allocated blocks */
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/*VARARGS1*/
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void GC_apply_to_all_blocks(fn, client_data)
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void (*fn)(/* struct hblk *h, word client_data */);
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word client_data;
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{
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register int j;
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register bottom_index * index_p;
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for (index_p = GC_all_bottom_indices; index_p != 0;
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index_p = index_p -> asc_link) {
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for (j = BOTTOM_SZ-1; j >= 0;) {
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if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
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if (index_p->index[j]->hb_map != GC_invalid_map) {
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(*fn)(((struct hblk *)
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(((index_p->key << LOG_BOTTOM_SZ) + (word)j)
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<< LOG_HBLKSIZE)),
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client_data);
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}
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j--;
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} else if (index_p->index[j] == 0) {
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j--;
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} else {
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j -= (word)(index_p->index[j]);
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}
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}
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}
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}
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/* Get the next valid block whose address is at least h */
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/* Return 0 if there is none. */
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struct hblk * GC_next_used_block(h)
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struct hblk * h;
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{
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register bottom_index * bi;
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register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
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GET_BI(h, bi);
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if (bi == GC_all_nils) {
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register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
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bi = GC_all_bottom_indices;
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while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
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j = 0;
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}
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while(bi != 0) {
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while (j < BOTTOM_SZ) {
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hdr * hhdr = bi -> index[j];
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if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
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j++;
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} else {
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if (hhdr->hb_map != GC_invalid_map) {
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return((struct hblk *)
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(((bi -> key << LOG_BOTTOM_SZ) + j)
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<< LOG_HBLKSIZE));
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} else {
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j += divHBLKSZ(hhdr -> hb_sz);
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}
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}
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}
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j = 0;
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bi = bi -> asc_link;
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}
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return(0);
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}
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/* Get the last (highest address) block whose address is */
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/* at most h. Return 0 if there is none. */
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/* Unlike the above, this may return a free block. */
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struct hblk * GC_prev_block(h)
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struct hblk * h;
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{
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register bottom_index * bi;
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register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
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GET_BI(h, bi);
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if (bi == GC_all_nils) {
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register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
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bi = GC_all_bottom_indices_end;
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while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
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j = BOTTOM_SZ - 1;
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}
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while(bi != 0) {
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while (j >= 0) {
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hdr * hhdr = bi -> index[j];
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if (0 == hhdr) {
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--j;
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} else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
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j -= (signed_word)hhdr;
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} else {
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return((struct hblk *)
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(((bi -> key << LOG_BOTTOM_SZ) + j)
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<< LOG_HBLKSIZE));
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}
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}
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j = BOTTOM_SZ - 1;
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bi = bi -> desc_link;
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}
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return(0);
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}
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