/vendor/gc/include/private/gc_hdrs.h
http://github.com/feyeleanor/RubyGoLightly · C++ Header · 206 lines · 117 code · 24 blank · 65 comment · 14 complexity · b0ccc90c8c3d54389a86dd85b80a0223 MD5 · raw file
- /*
- * 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.
- *
- * We 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 */
- # 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)
- #ifdef PRINT_BLACK_LIST
- hdr * GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce, ptr_t source);
- # define HEADER_CACHE_MISS(p, hce, source) \
- GC_header_cache_miss(p, hce, source)
- #else
- hdr * GC_header_cache_miss(ptr_t p, hdr_cache_entry *hce);
- # define HEADER_CACHE_MISS(p, hce, source) GC_header_cache_miss(p, hce)
- #endif
- /* Set hhdr to the header for p. Analogous to GET_HDR below, */
- /* except that in the case of large objects, it */
- /* gets the header for the object beginning, if GC_all_interior_ptrs */
- /* is set. */
- /* Returns zero if p points to somewhere other than the first page */
- /* of an object, and it is not a valid pointer to the object. */
- # define HC_GET_HDR(p, hhdr, source, exit_label) \
- { \
- hdr_cache_entry * hce = HCE(p); \
- if (EXPECT(HCE_VALID_FOR(hce, p), 1)) { \
- HC_HIT(); \
- hhdr = hce -> hce_hdr; \
- } else { \
- hhdr = HEADER_CACHE_MISS(p, hce, source); \
- if (0 == hhdr) goto exit_label; \
- } \
- }
- 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) ((size_t) (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) - (size_t)(hhdr))
- # endif /* GC_HEADERS_H */