--- /dev/null
+/*
+ * 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 */
+#if defined(LARGE_CONFIG) || !defined(SMALL_CONFIG)
+# define LOG_BOTTOM_SZ 10
+#else
+# define LOG_BOTTOM_SZ 11
+ /* Keep top index size reasonable with smaller blocks. */
+#endif
+#define BOTTOM_SZ (1 << LOG_BOTTOM_SZ)
+
+#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 COUNT_HDR_CACHE_HITS */
+
+#ifdef COUNT_HDR_CACHE_HITS
+ extern word GC_hdr_cache_hits; /* used for debugging/profiling */
+ 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
+ GC_INNER 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
+ GC_INNER 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), TRUE)) { \
+ 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;
+
+/* 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 NULL? */
+#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 */
projects / hs-boehmgc.git / blobdiff