mono/metadata/sgen-descriptor.c

   1 /*
   2  * Copyright 2001-2003 Ximian, Inc
   3  * Copyright 2003-2010 Novell, Inc.
   4  * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining
   7  * a copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sublicense, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be
  15  * included in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  21  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  22  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  23  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25 #include "config.h"
  26 #ifdef HAVE_SGEN_GC
  27
  28 #ifdef HAVE_UNISTD_H
  29 #include <unistd.h>
  30 #endif
  31 #ifdef HAVE_PTHREAD_H
  32 #include <pthread.h>
  33 #endif
  34 #ifdef HAVE_SEMAPHORE_H
  35 #include <semaphore.h>
  36 #endif
  37 #include <stdio.h>
  38 #include <string.h>
  39 #include <signal.h>
  40 #include <errno.h>
  41 #include <assert.h>
  42 #ifdef __MACH__
  43 #undef _XOPEN_SOURCE
  44 #endif
  45 #ifdef __MACH__
  46 #define _XOPEN_SOURCE
  47 #endif
  48
  49 #include "metadata/sgen-gc.h"
  50
  51 #define MAX_USER_DESCRIPTORS 16
  52
  53 #define MAKE_ROOT_DESC(type,val) ((type) | ((val) << ROOT_DESC_TYPE_SHIFT))
  54 #define ALIGN_TO(val,align) ((((guint64)val) + ((align) - 1)) & ~((align) - 1))
  55
  56
  57 static gsize* complex_descriptors = NULL;
  58 static int complex_descriptors_size = 0;
  59 static int complex_descriptors_next = 0;
  60 static MonoGCRootMarkFunc user_descriptors [MAX_USER_DESCRIPTORS];
  61 static int user_descriptors_next = 0;
  62 static void *all_ref_root_descrs [32];
  63
  64
  65 static int
  66 alloc_complex_descriptor (gsize *bitmap, int numbits)
  67 {
  68         int nwords, res, i;
  69
  70         numbits = ALIGN_TO (numbits, GC_BITS_PER_WORD);
  71         nwords = numbits / GC_BITS_PER_WORD + 1;
  72
  73         mono_sgen_gc_lock ();
  74         res = complex_descriptors_next;
  75         /* linear search, so we don't have duplicates with domain load/unload
  76          * this should not be performance critical or we'd have bigger issues
  77          * (the number and size of complex descriptors should be small).
  78          */
  79         for (i = 0; i < complex_descriptors_next; ) {
  80                 if (complex_descriptors [i] == nwords) {
  81                         int j, found = TRUE;
  82                         for (j = 0; j < nwords - 1; ++j) {
  83                                 if (complex_descriptors [i + 1 + j] != bitmap [j]) {
  84                                         found = FALSE;
  85                                         break;
  86                                 }
  87                         }
  88                         if (found) {
  89                                 mono_sgen_gc_unlock ();
  90                                 return i;
  91                         }
  92                 }
  93                 i += complex_descriptors [i];
  94         }
  95         if (complex_descriptors_next + nwords > complex_descriptors_size) {
  96                 int new_size = complex_descriptors_size * 2 + nwords;
  97                 complex_descriptors = g_realloc (complex_descriptors, new_size * sizeof (gsize));
  98                 complex_descriptors_size = new_size;
  99         }
 100         DEBUG (6, fprintf (gc_debug_file, "Complex descriptor %d, size: %d (total desc memory: %d)\n", res, nwords, complex_descriptors_size));
 101         complex_descriptors_next += nwords;
 102         complex_descriptors [res] = nwords;
 103         for (i = 0; i < nwords - 1; ++i) {
 104                 complex_descriptors [res + 1 + i] = bitmap [i];
 105                 DEBUG (6, fprintf (gc_debug_file, "\tvalue: %p\n", (void*)complex_descriptors [res + 1 + i]));
 106         }
 107         mono_sgen_gc_unlock ();
 108         return res;
 109 }
 110
 111 gsize*
 112 mono_sgen_get_complex_descriptor (mword desc)
 113 {
 114         return complex_descriptors + (desc >> LOW_TYPE_BITS);
 115 }
 116
 117 /*
 118  * Descriptor builders.
 119  */
 120 void*
 121 mono_gc_make_descr_for_string (gsize *bitmap, int numbits)
 122 {
 123         return (void*) DESC_TYPE_RUN_LENGTH;
 124 }
 125
 126 void*
 127 mono_gc_make_descr_for_object (gsize *bitmap, int numbits, size_t obj_size)
 128 {
 129         int first_set = -1, num_set = 0, last_set = -1, i;
 130         mword desc = 0;
 131         size_t stored_size = obj_size;
 132
 133         stored_size += SGEN_ALLOC_ALIGN - 1;
 134         stored_size &= ~(SGEN_ALLOC_ALIGN - 1);
 135
 136         for (i = 0; i < numbits; ++i) {
 137                 if (bitmap [i / GC_BITS_PER_WORD] & ((gsize)1 << (i % GC_BITS_PER_WORD))) {
 138                         if (first_set < 0)
 139                                 first_set = i;
 140                         last_set = i;
 141                         num_set++;
 142                 }
 143         }
 144
 145         if (first_set < 0) {
 146                 DEBUG (6, fprintf (gc_debug_file, "Ptrfree descriptor %p, size: %zd\n", (void*)desc, stored_size));
 147                 if (stored_size <= MAX_RUNLEN_OBJECT_SIZE)
 148                         return (void*)(DESC_TYPE_RUN_LENGTH | stored_size);
 149                 return (void*)DESC_TYPE_COMPLEX_PTRFREE;
 150         }
 151
 152         g_assert (!(stored_size & 0x7));
 153
 154         if (stored_size <= MAX_RUNLEN_OBJECT_SIZE) {
 155                 /* check run-length encoding first: one byte offset, one byte number of pointers
 156                  * on 64 bit archs, we can have 3 runs, just one on 32.
 157                  * It may be better to use nibbles.
 158                  */
 159                 if (first_set < 256 && num_set < 256 && (first_set + num_set == last_set + 1)) {
 160                         desc = DESC_TYPE_RUN_LENGTH | stored_size | (first_set << 16) | (num_set << 24);
 161                         DEBUG (6, fprintf (gc_debug_file, "Runlen descriptor %p, size: %zd, first set: %d, num set: %d\n", (void*)desc, stored_size, first_set, num_set));
 162                         return (void*) desc;
 163                 }
 164         }
 165
 166         /* we know the 2-word header is ptr-free */
 167         if (last_set < SMALL_BITMAP_SIZE + OBJECT_HEADER_WORDS) {
 168                 desc = DESC_TYPE_SMALL_BITMAP | stored_size | ((*bitmap >> OBJECT_HEADER_WORDS) << SMALL_BITMAP_SHIFT);
 169                 DEBUG (6, fprintf (gc_debug_file, "Smallbitmap descriptor %p, size: %zd, last set: %d\n", (void*)desc, stored_size, last_set));
 170                 return (void*) desc;
 171         }
 172
 173         /* we know the 2-word header is ptr-free */
 174         if (last_set < LARGE_BITMAP_SIZE + OBJECT_HEADER_WORDS) {
 175                 desc = DESC_TYPE_LARGE_BITMAP | ((*bitmap >> OBJECT_HEADER_WORDS) << LOW_TYPE_BITS);
 176                 DEBUG (6, fprintf (gc_debug_file, "Largebitmap descriptor %p, size: %zd, last set: %d\n", (void*)desc, stored_size, last_set));
 177                 return (void*) desc;
 178         }
 179         /* it's a complex object ... */
 180         desc = DESC_TYPE_COMPLEX | (alloc_complex_descriptor (bitmap, last_set + 1) << LOW_TYPE_BITS);
 181         return (void*) desc;
 182 }
 183
 184 /* If the array holds references, numbits == 1 and the first bit is set in elem_bitmap */
 185 void*
 186 mono_gc_make_descr_for_array (int vector, gsize *elem_bitmap, int numbits, size_t elem_size)
 187 {
 188         int first_set = -1, num_set = 0, last_set = -1, i;
 189         mword desc = DESC_TYPE_VECTOR | (vector ? VECTOR_KIND_SZARRAY : VECTOR_KIND_ARRAY);
 190         for (i = 0; i < numbits; ++i) {
 191                 if (elem_bitmap [i / GC_BITS_PER_WORD] & ((gsize)1 << (i % GC_BITS_PER_WORD))) {
 192                         if (first_set < 0)
 193                                 first_set = i;
 194                         last_set = i;
 195                         num_set++;
 196                 }
 197         }
 198
 199         if (first_set < 0) {
 200                 if (elem_size <= MAX_ELEMENT_SIZE)
 201                         return (void*)(desc | VECTOR_SUBTYPE_PTRFREE | (elem_size << VECTOR_ELSIZE_SHIFT));
 202                 return (void*)DESC_TYPE_COMPLEX_PTRFREE;
 203         }
 204
 205         if (elem_size <= MAX_ELEMENT_SIZE) {
 206                 desc |= elem_size << VECTOR_ELSIZE_SHIFT;
 207                 if (!num_set) {
 208                         return (void*)(desc | VECTOR_SUBTYPE_PTRFREE);
 209                 }
 210                 /* Note: we also handle structs with just ref fields */
 211                 if (num_set * sizeof (gpointer) == elem_size) {
 212                         return (void*)(desc | VECTOR_SUBTYPE_REFS | ((gssize)(-1) << 16));
 213                 }
 214                 /* FIXME: try run-len first */
 215                 /* Note: we can't skip the object header here, because it's not present */
 216                 if (last_set <= SMALL_BITMAP_SIZE) {
 217                         return (void*)(desc | VECTOR_SUBTYPE_BITMAP | (*elem_bitmap << 16));
 218                 }
 219         }
 220         /* it's am array of complex structs ... */
 221         desc = DESC_TYPE_COMPLEX_ARR;
 222         desc |= alloc_complex_descriptor (elem_bitmap, last_set + 1) << LOW_TYPE_BITS;
 223         return (void*) desc;
 224 }
 225
 226 /* Return the bitmap encoded by a descriptor */
 227 gsize*
 228 mono_gc_get_bitmap_for_descr (void *descr, int *numbits)
 229 {
 230         mword d = (mword)descr;
 231         gsize *bitmap;
 232
 233         switch (d & 0x7) {
 234         case DESC_TYPE_RUN_LENGTH: {
 235                 int first_set = (d >> 16) & 0xff;
 236                 int num_set = (d >> 24) & 0xff;
 237                 int i;
 238
 239                 bitmap = g_new0 (gsize, (first_set + num_set + 7) / 8);
 240
 241                 for (i = first_set; i < first_set + num_set; ++i)
 242                         bitmap [i / GC_BITS_PER_WORD] |= ((gsize)1 << (i % GC_BITS_PER_WORD));
 243
 244                 *numbits = first_set + num_set;
 245
 246                 return bitmap;
 247         }
 248
 249         case DESC_TYPE_SMALL_BITMAP:
 250                 bitmap = g_new0 (gsize, 1);
 251
 252                 bitmap [0] = (d >> SMALL_BITMAP_SHIFT) << OBJECT_HEADER_WORDS;
 253
 254                 *numbits = GC_BITS_PER_WORD;
 255                 return bitmap;
 256
 257         case DESC_TYPE_LARGE_BITMAP: {
 258                 gsize bmap = (d >> LOW_TYPE_BITS) << OBJECT_HEADER_WORDS;
 259
 260                 bitmap = g_new0 (gsize, 1);
 261                 bitmap [0] = bmap;
 262                 *numbits = 0;
 263                 while (bmap) {
 264                         (*numbits) ++;
 265                         bmap >>= 1;
 266                 }
 267                 return bitmap;
 268         }
 269         default:
 270                 g_assert_not_reached ();
 271         }
 272 }
 273
 274 void*
 275 mono_gc_make_descr_from_bitmap (gsize *bitmap, int numbits)
 276 {
 277         if (numbits == 0) {
 278                 return (void*)MAKE_ROOT_DESC (ROOT_DESC_BITMAP, 0);
 279         } else if (numbits < ((sizeof (*bitmap) * 8) - ROOT_DESC_TYPE_SHIFT)) {
 280                 return (void*)MAKE_ROOT_DESC (ROOT_DESC_BITMAP, bitmap [0]);
 281         } else {
 282                 mword complex = alloc_complex_descriptor (bitmap, numbits);
 283                 return (void*)MAKE_ROOT_DESC (ROOT_DESC_COMPLEX, complex);
 284         }
 285 }
 286
 287 void*
 288 mono_gc_make_root_descr_all_refs (int numbits)
 289 {
 290         gsize *gc_bitmap;
 291         void *descr;
 292         int num_bytes = numbits / 8;
 293
 294         if (numbits < 32 && all_ref_root_descrs [numbits])
 295                 return all_ref_root_descrs [numbits];
 296
 297         gc_bitmap = g_malloc0 (ALIGN_TO (ALIGN_TO (numbits, 8) + 1, sizeof (gsize)));
 298         memset (gc_bitmap, 0xff, num_bytes);
 299         if (numbits < ((sizeof (*gc_bitmap) * 8) - ROOT_DESC_TYPE_SHIFT))
 300                 gc_bitmap[0] = GUINT64_TO_LE(gc_bitmap[0]);
 301         else if (numbits && num_bytes % (sizeof (*gc_bitmap)))
 302                 gc_bitmap[num_bytes / 8] = GUINT64_TO_LE(gc_bitmap [num_bytes / 8]);
 303         if (numbits % 8)
 304                 gc_bitmap [numbits / 8] = (1 << (numbits % 8)) - 1;
 305         descr = mono_gc_make_descr_from_bitmap (gc_bitmap, numbits);
 306         g_free (gc_bitmap);
 307
 308         if (numbits < 32)
 309                 all_ref_root_descrs [numbits] = descr;
 310
 311         return descr;
 312 }
 313
 314 void*
 315 mono_gc_make_root_descr_user (MonoGCRootMarkFunc marker)
 316 {
 317         void *descr;
 318
 319         g_assert (user_descriptors_next < MAX_USER_DESCRIPTORS);
 320         descr = (void*)MAKE_ROOT_DESC (ROOT_DESC_USER, (mword)user_descriptors_next);
 321         user_descriptors [user_descriptors_next ++] = marker;
 322
 323         return descr;
 324 }
 325
 326 void*
 327 mono_sgen_get_complex_descriptor_bitmap (mword desc)
 328 {
 329         return complex_descriptors + (desc >> ROOT_DESC_TYPE_SHIFT);
 330 }
 331
 332 MonoGCRootMarkFunc
 333 mono_sgen_get_user_descriptor_func (mword desc)
 334 {
 335         return user_descriptors [desc >> ROOT_DESC_TYPE_SHIFT];
 336 }
 337
 338 #endif