234 lines
7.2 KiB
C
234 lines
7.2 KiB
C
/*
|
|
* 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 */
|