Annotation of OpenXM_contrib/gc/gc_hdrs.h, Revision 1.1.1.3
1.1 maekawa 1: /*
2: * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3: * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
4: *
5: * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
6: * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
7: *
8: * Permission is hereby granted to use or copy this program
9: * for any purpose, provided the above notices are retained on all copies.
10: * Permission to modify the code and to distribute modified code is granted,
11: * provided the above notices are retained, and a notice that the code was
12: * modified is included with the above copyright notice.
13: */
14: /* Boehm, July 11, 1995 11:54 am PDT */
15: # ifndef GC_HEADERS_H
16: # define GC_HEADERS_H
17: typedef struct hblkhdr hdr;
18:
19: # if CPP_WORDSZ != 32 && CPP_WORDSZ < 36
20: --> Get a real machine.
21: # endif
22:
23: /*
24: * The 2 level tree data structure that is used to find block headers.
25: * If there are more than 32 bits in a pointer, the top level is a hash
26: * table.
1.1.1.3 ! maekawa 27: *
! 28: * This defines HDR, GET_HDR, and SET_HDR, the main macros used to
! 29: * retrieve and set object headers. We also define some variants to
! 30: * retrieve 2 unrelated headers in interleaved fashion. This
! 31: * slightly improves scheduling.
! 32: *
! 33: * Since 5.0 alpha 5, we can also take advantage of a header lookup
! 34: * cache. This is a locally declared direct mapped cache, used inside
! 35: * the marker. The HC_GET_HDR and HC_GET_HDR2 macros use and maintain this
! 36: * cache. Assuming we get reasonable hit rates, this shaves a few
! 37: * memory references from each pointer validation.
1.1 maekawa 38: */
39:
40: # if CPP_WORDSZ > 32
41: # define HASH_TL
42: # endif
43:
44: /* Define appropriate out-degrees for each of the two tree levels */
45: # ifdef SMALL_CONFIG
46: # define LOG_BOTTOM_SZ 11
47: /* Keep top index size reasonable with smaller blocks. */
48: # else
49: # define LOG_BOTTOM_SZ 10
50: # endif
51: # ifndef HASH_TL
52: # define LOG_TOP_SZ (WORDSZ - LOG_BOTTOM_SZ - LOG_HBLKSIZE)
53: # else
54: # define LOG_TOP_SZ 11
55: # endif
56: # define TOP_SZ (1 << LOG_TOP_SZ)
57: # define BOTTOM_SZ (1 << LOG_BOTTOM_SZ)
58:
1.1.1.3 ! maekawa 59: #ifndef SMALL_CONFIG
! 60: # define USE_HDR_CACHE
! 61: #endif
! 62:
! 63: /* #define COUNT_HDR_CACHE_HITS */
! 64:
! 65: extern hdr * GC_invalid_header; /* header for an imaginary block */
! 66: /* containing no objects. */
! 67:
! 68:
! 69: /* Check whether p and corresponding hhdr point to long or invalid */
! 70: /* object. If so, advance them to */
! 71: /* beginning of block, or set hhdr to GC_invalid_header. */
! 72: #define ADVANCE(p, hhdr, source) \
! 73: if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \
! 74: p = GC_FIND_START(p, hhdr, (word)source); \
! 75: if (p == 0) { \
! 76: hhdr = GC_invalid_header; \
! 77: } else { \
! 78: hhdr = GC_find_header(p); \
! 79: } \
! 80: }
! 81:
! 82: #ifdef USE_HDR_CACHE
! 83:
! 84: # ifdef COUNT_HDR_CACHE_HITS
! 85: extern word GC_hdr_cache_hits;
! 86: extern word GC_hdr_cache_misses;
! 87: # define HC_HIT() ++GC_hdr_cache_hits
! 88: # define HC_MISS() ++GC_hdr_cache_misses
! 89: # else
! 90: # define HC_HIT()
! 91: # define HC_MISS()
! 92: # endif
! 93:
! 94: typedef struct hce {
! 95: word block_addr; /* right shifted by LOG_HBLKSIZE */
! 96: hdr * hce_hdr;
! 97: } hdr_cache_entry;
! 98:
! 99: # define HDR_CACHE_SIZE 8 /* power of 2 */
! 100:
! 101: # define DECLARE_HDR_CACHE \
! 102: hdr_cache_entry hdr_cache[HDR_CACHE_SIZE]
! 103:
! 104: # define INIT_HDR_CACHE BZERO(hdr_cache, sizeof(hdr_cache));
! 105:
! 106: # define HCE(h) hdr_cache + (((word)(h) >> LOG_HBLKSIZE) & (HDR_CACHE_SIZE-1))
! 107:
! 108: # define HCE_VALID_FOR(hce,h) ((hce) -> block_addr == \
! 109: ((word)(h) >> LOG_HBLKSIZE))
! 110:
! 111: # define HCE_HDR(h) ((hce) -> hce_hdr)
! 112:
! 113:
! 114: /* Analogous to GET_HDR, except that in the case of large objects, it */
! 115: /* Returns the header for the object beginning, and updates p. */
! 116: /* Returns &GC_bad_header instead of 0. All of this saves a branch */
! 117: /* in the fast path. */
! 118: # define HC_GET_HDR(p, hhdr, source) \
! 119: { \
! 120: hdr_cache_entry * hce = HCE(p); \
! 121: if (HCE_VALID_FOR(hce, p)) { \
! 122: HC_HIT(); \
! 123: hhdr = hce -> hce_hdr; \
! 124: } else { \
! 125: HC_MISS(); \
! 126: GET_HDR(p, hhdr); \
! 127: ADVANCE(p, hhdr, source); \
! 128: hce -> block_addr = (word)(p) >> LOG_HBLKSIZE; \
! 129: hce -> hce_hdr = hhdr; \
! 130: } \
! 131: }
! 132:
! 133: # define HC_GET_HDR2(p1, hhdr1, source1, p2, hhdr2, source2) \
! 134: { \
! 135: hdr_cache_entry * hce1 = HCE(p1); \
! 136: hdr_cache_entry * hce2 = HCE(p2); \
! 137: if (HCE_VALID_FOR(hce1, p1)) { \
! 138: HC_HIT(); \
! 139: hhdr1 = hce1 -> hce_hdr; \
! 140: } else { \
! 141: HC_MISS(); \
! 142: GET_HDR(p1, hhdr1); \
! 143: ADVANCE(p1, hhdr1, source1); \
! 144: hce1 -> block_addr = (word)(p1) >> LOG_HBLKSIZE; \
! 145: hce1 -> hce_hdr = hhdr1; \
! 146: } \
! 147: if (HCE_VALID_FOR(hce2, p2)) { \
! 148: HC_HIT(); \
! 149: hhdr2 = hce2 -> hce_hdr; \
! 150: } else { \
! 151: HC_MISS(); \
! 152: GET_HDR(p2, hhdr2); \
! 153: ADVANCE(p2, hhdr2, source2); \
! 154: hce2 -> block_addr = (word)(p2) >> LOG_HBLKSIZE; \
! 155: hce2 -> hce_hdr = hhdr2; \
! 156: } \
! 157: }
! 158:
! 159: #else /* !USE_HDR_CACHE */
! 160:
! 161: # define DECLARE_HDR_CACHE
! 162:
! 163: # define INIT_HDR_CACHE
! 164:
! 165: # define HC_GET_HDR(p, hhdr, source) \
! 166: { \
! 167: GET_HDR(p, hhdr); \
! 168: ADVANCE(p, hhdr, source); \
! 169: }
! 170:
! 171: # define HC_GET_HDR2(p1, hhdr1, source1, p2, hhdr2, source2) \
! 172: { \
! 173: GET_HDR2(p1, hhdr1, p2, hhdr2); \
! 174: ADVANCE(p1, hhdr1, source1); \
! 175: ADVANCE(p2, hhdr2, source2); \
! 176: }
! 177:
! 178: #endif
! 179:
1.1 maekawa 180: typedef struct bi {
181: hdr * index[BOTTOM_SZ];
182: /*
183: * The bottom level index contains one of three kinds of values:
1.1.1.2 maekawa 184: * 0 means we're not responsible for this block,
185: * or this is a block other than the first one in a free block.
1.1 maekawa 186: * 1 < (long)X <= MAX_JUMP means the block starts at least
187: * X * HBLKSIZE bytes before the current address.
188: * A valid pointer points to a hdr structure. (The above can't be
189: * valid pointers due to the GET_MEM return convention.)
190: */
191: struct bi * asc_link; /* All indices are linked in */
1.1.1.2 maekawa 192: /* ascending order... */
193: struct bi * desc_link; /* ... and in descending order. */
1.1 maekawa 194: word key; /* high order address bits. */
195: # ifdef HASH_TL
196: struct bi * hash_link; /* Hash chain link. */
197: # endif
198: } bottom_index;
199:
200: /* extern bottom_index GC_all_nils; - really part of GC_arrays */
201:
202: /* extern bottom_index * GC_top_index []; - really part of GC_arrays */
203: /* Each entry points to a bottom_index. */
204: /* On a 32 bit machine, it points to */
205: /* the index for a set of high order */
206: /* bits equal to the index. For longer */
207: /* addresses, we hash the high order */
208: /* bits to compute the index in */
209: /* GC_top_index, and each entry points */
210: /* to a hash chain. */
211: /* The last entry in each chain is */
212: /* GC_all_nils. */
213:
214:
215: # define MAX_JUMP (HBLKSIZE - 1)
216:
217: # define HDR_FROM_BI(bi, p) \
218: ((bi)->index[((word)(p) >> LOG_HBLKSIZE) & (BOTTOM_SZ - 1)])
219: # ifndef HASH_TL
220: # define BI(p) (GC_top_index \
221: [(word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE)])
222: # define HDR_INNER(p) HDR_FROM_BI(BI(p),p)
223: # ifdef SMALL_CONFIG
224: # define HDR(p) GC_find_header((ptr_t)(p))
225: # else
226: # define HDR(p) HDR_INNER(p)
227: # endif
228: # define GET_BI(p, bottom_indx) (bottom_indx) = BI(p)
229: # define GET_HDR(p, hhdr) (hhdr) = HDR(p)
230: # define SET_HDR(p, hhdr) HDR_INNER(p) = (hhdr)
231: # define GET_HDR_ADDR(p, ha) (ha) = &(HDR_INNER(p))
1.1.1.3 ! maekawa 232: # define GET_HDR2(p1, hhdr1, p2, hhdr2) \
! 233: { GET_HDR(p1, hhdr1); GET_HDR(p2, hhdr2); }
1.1 maekawa 234: # else /* hash */
235: /* Hash function for tree top level */
236: # define TL_HASH(hi) ((hi) & (TOP_SZ - 1))
237: /* Set bottom_indx to point to the bottom index for address p */
238: # define GET_BI(p, bottom_indx) \
239: { \
240: register word hi = \
241: (word)(p) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \
242: register bottom_index * _bi = GC_top_index[TL_HASH(hi)]; \
243: \
244: while (_bi -> key != hi && _bi != GC_all_nils) \
245: _bi = _bi -> hash_link; \
246: (bottom_indx) = _bi; \
247: }
248: # define GET_HDR_ADDR(p, ha) \
249: { \
250: register bottom_index * bi; \
251: \
252: GET_BI(p, bi); \
253: (ha) = &(HDR_FROM_BI(bi, p)); \
254: }
255: # define GET_HDR(p, hhdr) { register hdr ** _ha; GET_HDR_ADDR(p, _ha); \
256: (hhdr) = *_ha; }
257: # define SET_HDR(p, hhdr) { register hdr ** _ha; GET_HDR_ADDR(p, _ha); \
258: *_ha = (hhdr); }
259: # define HDR(p) GC_find_header((ptr_t)(p))
1.1.1.3 ! maekawa 260: /* And some interleaved versions for two pointers at once. */
! 261: /* This hopefully helps scheduling on processors like IA64. */
! 262: # define GET_BI2(p1, bottom_indx1, p2, bottom_indx2) \
! 263: { \
! 264: register word hi1 = \
! 265: (word)(p1) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \
! 266: register word hi2 = \
! 267: (word)(p2) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE); \
! 268: register bottom_index * _bi1 = GC_top_index[TL_HASH(hi1)]; \
! 269: register bottom_index * _bi2 = GC_top_index[TL_HASH(hi2)]; \
! 270: \
! 271: while (_bi1 -> key != hi1 && _bi1 != GC_all_nils) \
! 272: _bi1 = _bi1 -> hash_link; \
! 273: while (_bi2 -> key != hi2 && _bi2 != GC_all_nils) \
! 274: _bi2 = _bi2 -> hash_link; \
! 275: (bottom_indx1) = _bi1; \
! 276: (bottom_indx2) = _bi2; \
! 277: }
! 278: # define GET_HDR_ADDR2(p1, ha1, p2, ha2) \
! 279: { \
! 280: register bottom_index * bi1; \
! 281: register bottom_index * bi2; \
! 282: \
! 283: GET_BI2(p1, bi1, p2, bi2); \
! 284: (ha1) = &(HDR_FROM_BI(bi1, p1)); \
! 285: (ha2) = &(HDR_FROM_BI(bi2, p2)); \
! 286: }
! 287: # define GET_HDR2(p1, hhdr1, p2, hhdr2) \
! 288: { register hdr ** _ha1; \
! 289: register hdr ** _ha2; \
! 290: GET_HDR_ADDR2(p1, _ha1, p2, _ha2); \
! 291: (hhdr1) = *_ha1; \
! 292: (hhdr2) = *_ha2; \
! 293: }
1.1 maekawa 294: # endif
295:
296: /* Is the result a forwarding address to someplace closer to the */
297: /* beginning of the block or NIL? */
298: # define IS_FORWARDING_ADDR_OR_NIL(hhdr) ((unsigned long) (hhdr) <= MAX_JUMP)
299:
300: /* Get an HBLKSIZE aligned address closer to the beginning of the block */
301: /* h. Assumes hhdr == HDR(h) and IS_FORWARDING_ADDR(hhdr). */
302: # define FORWARDED_ADDR(h, hhdr) ((struct hblk *)(h) - (unsigned long)(hhdr))
303: # endif /* GC_HEADERS_H */
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