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-/*
- * 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 also define some variants to
- * retrieve 2 unrelated headers in interleaved fashion. This
- * slightly improves scheduling.
- *
- * 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 and HC_GET_HDR2 macros use and maintain 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 them to */
-/* beginning of block, or set hhdr to GC_invalid_header. */
-#define ADVANCE(p, hhdr, source) \
- if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \
- p = GC_FIND_START(p, hhdr, (word)source); \
- if (p == 0) { \
- hhdr = GC_invalid_header; \
- } else { \
- hhdr = GC_find_header(p); \
- } \
- }
-
-#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_bad_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); \
- ADVANCE(p, hhdr, source); \
- hce -> block_addr = (word)(p) >> LOG_HBLKSIZE; \
- hce -> hce_hdr = hhdr; \
- } \
- }
-
-# define HC_GET_HDR2(p1, hhdr1, source1, p2, hhdr2, source2) \
- { \
- hdr_cache_entry * hce1 = HCE(p1); \
- hdr_cache_entry * hce2 = HCE(p2); \
- if (HCE_VALID_FOR(hce1, p1)) { \
- HC_HIT(); \
- hhdr1 = hce1 -> hce_hdr; \
- } else { \
- HC_MISS(); \
- GET_HDR(p1, hhdr1); \
- ADVANCE(p1, hhdr1, source1); \
- hce1 -> block_addr = (word)(p1) >> LOG_HBLKSIZE; \
- hce1 -> hce_hdr = hhdr1; \
- } \
- if (HCE_VALID_FOR(hce2, p2)) { \
- HC_HIT(); \
- hhdr2 = hce2 -> hce_hdr; \
- } else { \
- HC_MISS(); \
- GET_HDR(p2, hhdr2); \
- ADVANCE(p2, hhdr2, source2); \
- hce2 -> block_addr = (word)(p2) >> LOG_HBLKSIZE; \
- hce2 -> hce_hdr = hhdr2; \
- } \
- }
-
-#else /* !USE_HDR_CACHE */
-
-# define DECLARE_HDR_CACHE
-
-# define INIT_HDR_CACHE
-
-# define HC_GET_HDR(p, hhdr, source) \
- { \
- GET_HDR(p, hhdr); \
- ADVANCE(p, hhdr, source); \
- }
-
-# define HC_GET_HDR2(p1, hhdr1, source1, p2, hhdr2, source2) \
- { \
- GET_HDR2(p1, hhdr1, p2, hhdr2); \
- ADVANCE(p1, hhdr1, source1); \
- ADVANCE(p2, hhdr2, source2); \
- }
-
-#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))
-# define GET_HDR2(p1, hhdr1, p2, hhdr2) \
- { GET_HDR(p1, hhdr1); GET_HDR(p2, hhdr2); }
-# 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))
- /* And some interleaved versions for two pointers at once. */
- /* This hopefully helps scheduling on processors like IA64. */
-# define GET_BI2(p1, bottom_indx1, p2, bottom_indx2) \
- { \
- register word hi1 = \
- (word)(p1) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \
- register word hi2 = \
- (word)(p2) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \
- register bottom_index * _bi1 = GC_top_index[TL_HASH(hi1)]; \
- register bottom_index * _bi2 = GC_top_index[TL_HASH(hi2)]; \
- \
- while (_bi1 -> key != hi1 && _bi1 != GC_all_nils) \
- _bi1 = _bi1 -> hash_link; \
- while (_bi2 -> key != hi2 && _bi2 != GC_all_nils) \
- _bi2 = _bi2 -> hash_link; \
- (bottom_indx1) = _bi1; \
- (bottom_indx2) = _bi2; \
- }
-# define GET_HDR_ADDR2(p1, ha1, p2, ha2) \
- { \
- register bottom_index * bi1; \
- register bottom_index * bi2; \
- \
- GET_BI2(p1, bi1, p2, bi2); \
- (ha1) = &(HDR_FROM_BI(bi1, p1)); \
- (ha2) = &(HDR_FROM_BI(bi2, p2)); \
- }
-# define GET_HDR2(p1, hhdr1, p2, hhdr2) \
- { register hdr ** _ha1; \
- register hdr ** _ha2; \
- GET_HDR_ADDR2(p1, _ha1, p2, _ha2); \
- (hhdr1) = *_ha1; \
- (hhdr2) = *_ha2; \
- }
-# 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 */