| /* |
| * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers |
| * Copyright (c) 1991-1994 by Xerox Corporation. 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. |
| */ |
| /* Boehm, July 11, 1995 11:54 am PDT */ |
| # ifndef GC_HEADERS_H |
| # define GC_HEADERS_H |
| typedef struct hblkhdr hdr; |
| |
| # if CPP_WORDSZ != 32 && CPP_WORDSZ < 36 |
| --> Get a real machine. |
| # endif |
| |
| /* |
| * The 2 level tree data structure that is used to find block headers. |
| * If there are more than 32 bits in a pointer, the top level is a hash |
| * table. |
| * |
| * This defines HDR, GET_HDR, and SET_HDR, the main macros used to |
| * retrieve and set object headers. |
| * |
| * Since 5.0 alpha 5, we can also take advantage of a header lookup |
| * cache. This is a locally declared direct mapped cache, used inside |
| * the marker. The HC_GET_HDR macro uses and maintains this |
| * cache. Assuming we get reasonable hit rates, this shaves a few |
| * memory references from each pointer validation. |
| */ |
| |
| # if CPP_WORDSZ > 32 |
| # define HASH_TL |
| # endif |
| |
| /* Define appropriate out-degrees for each of the two tree levels */ |
| # ifdef SMALL_CONFIG |
| # define LOG_BOTTOM_SZ 11 |
| /* Keep top index size reasonable with smaller blocks. */ |
| # else |
| # define LOG_BOTTOM_SZ 10 |
| # endif |
| # ifndef HASH_TL |
| # define LOG_TOP_SZ (WORDSZ - LOG_BOTTOM_SZ - LOG_HBLKSIZE) |
| # else |
| # define LOG_TOP_SZ 11 |
| # endif |
| # define TOP_SZ (1 << LOG_TOP_SZ) |
| # define BOTTOM_SZ (1 << LOG_BOTTOM_SZ) |
| |
| #ifndef SMALL_CONFIG |
| # define USE_HDR_CACHE |
| #endif |
| |
| /* #define COUNT_HDR_CACHE_HITS */ |
| |
| extern hdr * GC_invalid_header; /* header for an imaginary block */ |
| /* containing no objects. */ |
| |
| |
| /* Check whether p and corresponding hhdr point to long or invalid */ |
| /* object. If so, advance hhdr to */ |
| /* beginning of block, or set hhdr to GC_invalid_header. */ |
| #define ADVANCE(p, hhdr, source) \ |
| { \ |
| hdr * new_hdr = GC_invalid_header; \ |
| p = GC_find_start(p, hhdr, &new_hdr); \ |
| hhdr = new_hdr; \ |
| } |
| |
| #ifdef USE_HDR_CACHE |
| |
| # ifdef COUNT_HDR_CACHE_HITS |
| extern word GC_hdr_cache_hits; |
| extern word GC_hdr_cache_misses; |
| # define HC_HIT() ++GC_hdr_cache_hits |
| # define HC_MISS() ++GC_hdr_cache_misses |
| # else |
| # define HC_HIT() |
| # define HC_MISS() |
| # endif |
| |
| typedef struct hce { |
| word block_addr; /* right shifted by LOG_HBLKSIZE */ |
| hdr * hce_hdr; |
| } hdr_cache_entry; |
| |
| # define HDR_CACHE_SIZE 8 /* power of 2 */ |
| |
| # define DECLARE_HDR_CACHE \ |
| hdr_cache_entry hdr_cache[HDR_CACHE_SIZE] |
| |
| # define INIT_HDR_CACHE BZERO(hdr_cache, sizeof(hdr_cache)); |
| |
| # define HCE(h) hdr_cache + (((word)(h) >> LOG_HBLKSIZE) & (HDR_CACHE_SIZE-1)) |
| |
| # define HCE_VALID_FOR(hce,h) ((hce) -> block_addr == \ |
| ((word)(h) >> LOG_HBLKSIZE)) |
| |
| # define HCE_HDR(h) ((hce) -> hce_hdr) |
| |
| |
| /* Analogous to GET_HDR, except that in the case of large objects, it */ |
| /* Returns the header for the object beginning, and updates p. */ |
| /* Returns GC_invalid_header instead of 0. All of this saves a branch */ |
| /* in the fast path. */ |
| # define HC_GET_HDR(p, hhdr, source) \ |
| { \ |
| hdr_cache_entry * hce = HCE(p); \ |
| if (HCE_VALID_FOR(hce, p)) { \ |
| HC_HIT(); \ |
| hhdr = hce -> hce_hdr; \ |
| } else { \ |
| HC_MISS(); \ |
| GET_HDR(p, hhdr); \ |
| if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \ |
| ADVANCE(p, hhdr, source); \ |
| } else { \ |
| hce -> block_addr = (word)(p) >> LOG_HBLKSIZE; \ |
| hce -> hce_hdr = hhdr; \ |
| } \ |
| } \ |
| } |
| |
| #else /* !USE_HDR_CACHE */ |
| |
| # define DECLARE_HDR_CACHE |
| |
| # define INIT_HDR_CACHE |
| |
| # define HC_GET_HDR(p, hhdr, source) \ |
| { \ |
| GET_HDR(p, hhdr); \ |
| if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \ |
| ADVANCE(p, hhdr, source); \ |
| } \ |
| } |
| #endif |
| |
| typedef struct bi { |
| hdr * index[BOTTOM_SZ]; |
| /* |
| * The bottom level index contains one of three kinds of values: |
| * 0 means we're not responsible for this block, |
| * or this is a block other than the first one in a free block. |
| * 1 < (long)X <= MAX_JUMP means the block starts at least |
| * X * HBLKSIZE bytes before the current address. |
| * A valid pointer points to a hdr structure. (The above can't be |
| * valid pointers due to the GET_MEM return convention.) |
| */ |
| struct bi * asc_link; /* All indices are linked in */ |
| /* ascending order... */ |
| struct bi * desc_link; /* ... and in descending order. */ |
| word key; /* high order address bits. */ |
| # ifdef HASH_TL |
| struct bi * hash_link; /* Hash chain link. */ |
| # endif |
| } bottom_index; |
| |
| /* extern bottom_index GC_all_nils; - really part of GC_arrays */ |
| |
| /* extern bottom_index * GC_top_index []; - really part of GC_arrays */ |
| /* Each entry points to a bottom_index. */ |
| /* On a 32 bit machine, it points to */ |
| /* the index for a set of high order */ |
| /* bits equal to the index. For longer */ |
| /* addresses, we hash the high order */ |
| /* bits to compute the index in */ |
| /* GC_top_index, and each entry points */ |
| /* to a hash chain. */ |
| /* The last entry in each chain is */ |
| /* GC_all_nils. */ |
| |
| |
| # define MAX_JUMP (HBLKSIZE - 1) |
| |
| # define HDR_FROM_BI(bi, p) \ |
| ((bi)->index[((word)(p) >> LOG_HBLKSIZE) & (BOTTOM_SZ - 1)]) |
| # ifndef HASH_TL |
| # define BI(p) (GC_top_index \ |
| [(word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE)]) |
| # define HDR_INNER(p) HDR_FROM_BI(BI(p),p) |
| # ifdef SMALL_CONFIG |
| # define HDR(p) GC_find_header((ptr_t)(p)) |
| # else |
| # define HDR(p) HDR_INNER(p) |
| # endif |
| # define GET_BI(p, bottom_indx) (bottom_indx) = BI(p) |
| # define GET_HDR(p, hhdr) (hhdr) = HDR(p) |
| # define SET_HDR(p, hhdr) HDR_INNER(p) = (hhdr) |
| # define GET_HDR_ADDR(p, ha) (ha) = &(HDR_INNER(p)) |
| # else /* hash */ |
| /* Hash function for tree top level */ |
| # define TL_HASH(hi) ((hi) & (TOP_SZ - 1)) |
| /* Set bottom_indx to point to the bottom index for address p */ |
| # define GET_BI(p, bottom_indx) \ |
| { \ |
| register word hi = \ |
| (word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \ |
| register bottom_index * _bi = GC_top_index[TL_HASH(hi)]; \ |
| \ |
| while (_bi -> key != hi && _bi != GC_all_nils) \ |
| _bi = _bi -> hash_link; \ |
| (bottom_indx) = _bi; \ |
| } |
| # define GET_HDR_ADDR(p, ha) \ |
| { \ |
| register bottom_index * bi; \ |
| \ |
| GET_BI(p, bi); \ |
| (ha) = &(HDR_FROM_BI(bi, p)); \ |
| } |
| # define GET_HDR(p, hhdr) { register hdr ** _ha; GET_HDR_ADDR(p, _ha); \ |
| (hhdr) = *_ha; } |
| # define SET_HDR(p, hhdr) { register hdr ** _ha; GET_HDR_ADDR(p, _ha); \ |
| *_ha = (hhdr); } |
| # define HDR(p) GC_find_header((ptr_t)(p)) |
| # endif |
| |
| /* Is the result a forwarding address to someplace closer to the */ |
| /* beginning of the block or NIL? */ |
| # define IS_FORWARDING_ADDR_OR_NIL(hhdr) ((unsigned long) (hhdr) <= MAX_JUMP) |
| |
| /* Get an HBLKSIZE aligned address closer to the beginning of the block */ |
| /* h. Assumes hhdr == HDR(h) and IS_FORWARDING_ADDR(hhdr). */ |
| # define FORWARDED_ADDR(h, hhdr) ((struct hblk *)(h) - (unsigned long)(hhdr)) |
| # endif /* GC_HEADERS_H */ |