gcc/alloc-pool.h

   1 /* Functions to support a pool of allocatable objects
   2    Copyright (C) 1997-2017 Free Software Foundation, Inc.
   3    Contributed by Daniel Berlin <dan@cgsoftware.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20 #ifndef ALLOC_POOL_H
  21 #define ALLOC_POOL_H
  22
  23 #include "memory-block.h"
  24 #include "options.h"        // for flag_checking
  25
  26 extern void dump_alloc_pool_statistics (void);
  27
  28 /* Flag indicates whether memory statistics are gathered any longer.  */
  29 extern bool after_memory_report;
  30
  31 typedef unsigned long ALLOC_POOL_ID_TYPE;
  32
  33 /* Last used ID.  */
  34 extern ALLOC_POOL_ID_TYPE last_id;
  35
  36 /* Pool allocator memory usage.  */
  37 struct pool_usage: public mem_usage
  38 {
  39   /* Default contructor.  */
  40   pool_usage (): m_element_size (0), m_pool_name ("") {}
  41   /* Constructor.  */
  42   pool_usage (size_t allocated, size_t times, size_t peak,
  43               size_t instances, size_t element_size,
  44               const char *pool_name)
  45     : mem_usage (allocated, times, peak, instances),
  46       m_element_size (element_size),
  47       m_pool_name (pool_name) {}
  48
  49   /* Sum the usage with SECOND usage.  */
  50   pool_usage
  51   operator+ (const pool_usage &second)
  52   {
  53     return pool_usage (m_allocated + second.m_allocated,
  54                              m_times + second.m_times,
  55                              m_peak + second.m_peak,
  56                              m_instances + second.m_instances,
  57                              m_element_size, m_pool_name);
  58   }
  59
  60   /* Dump usage coupled to LOC location, where TOTAL is sum of all rows.  */
  61   inline void
  62   dump (mem_location *loc, mem_usage &total) const
  63   {
  64     char *location_string = loc->to_string ();
  65
  66     fprintf (stderr, "%-32s%-48s %6li%10li:%5.1f%%%10li%10li:%5.1f%%%12li\n",
  67              m_pool_name, location_string, (long)m_instances,
  68              (long)m_allocated, get_percent (m_allocated, total.m_allocated),
  69              (long)m_peak, (long)m_times,
  70              get_percent (m_times, total.m_times),
  71              (long)m_element_size);
  72
  73     free (location_string);
  74   }
  75
  76   /* Dump header with NAME.  */
  77   static inline void
  78   dump_header (const char *name)
  79   {
  80     fprintf (stderr, "%-32s%-48s %6s%11s%16s%17s%12s\n", "Pool name", name,
  81              "Pools", "Leak", "Peak", "Times", "Elt size");
  82     print_dash_line ();
  83   }
  84
  85   /* Dump footer.  */
  86   inline void
  87   dump_footer ()
  88   {
  89     print_dash_line ();
  90     fprintf (stderr, "%s%82li%10li\n", "Total", (long)m_instances,
  91              (long)m_allocated);
  92     print_dash_line ();
  93   }
  94
  95   /* Element size.  */
  96   size_t m_element_size;
  97   /* Pool name.  */
  98   const char *m_pool_name;
  99 };
 100
 101 extern mem_alloc_description<pool_usage> pool_allocator_usage;
 102
 103 #if 0
 104 /* If a pool with custom block size is needed, one might use the following
 105    template.  An instance of this template can be used as a parameter for
 106    instantiating base_pool_allocator template:
 107
 108         typedef custom_block_allocator <128*1024> huge_block_allocator;
 109         ...
 110         static base_pool_allocator <huge_block_allocator>
 111                                                 value_pool ("value", 16384);
 112
 113    Right now it's not used anywhere in the code, and is given here as an
 114    example).  */
 115
 116 template <size_t BlockSize>
 117 class custom_block_allocator
 118 {
 119 public:
 120   static const size_t block_size = BlockSize;
 121
 122   static inline void *
 123   allocate () ATTRIBUTE_MALLOC
 124   {
 125     return XNEWVEC (char, BlockSize);
 126   }
 127
 128   static inline void
 129   release (void *block)
 130   {
 131     XDELETEVEC (block);
 132   }
 133 };
 134 #endif
 135
 136 /* Generic pool allocator.  */
 137
 138 template <typename TBlockAllocator>
 139 class base_pool_allocator
 140 {
 141 public:
 142   /* Default constructor for pool allocator called NAME.  */
 143   base_pool_allocator (const char *name, size_t size CXX_MEM_STAT_INFO);
 144   ~base_pool_allocator ();
 145   void release ();
 146   void release_if_empty ();
 147   void *allocate () ATTRIBUTE_MALLOC;
 148   void remove (void *object);
 149   size_t num_elts_current ();
 150
 151 private:
 152   struct allocation_pool_list
 153   {
 154     allocation_pool_list *next;
 155   };
 156
 157   /* Initialize a pool allocator.  */
 158   void initialize ();
 159
 160   struct allocation_object
 161   {
 162 #if CHECKING_P
 163     /* The ID of alloc pool which the object was allocated from.  */
 164     ALLOC_POOL_ID_TYPE id;
 165 #endif
 166
 167     union
 168       {
 169         /* The data of the object.  */
 170         char data[1];
 171
 172         /* Because we want any type of data to be well aligned after the ID,
 173            the following elements are here.  They are never accessed so
 174            the allocated object may be even smaller than this structure.
 175            We do not care about alignment for floating-point types.  */
 176         char *align_p;
 177         int64_t align_i;
 178       } u;
 179
 180 #if CHECKING_P
 181     static inline allocation_object*
 182     get_instance (void *data_ptr)
 183     {
 184       return (allocation_object *)(((char *)(data_ptr))
 185                                       - offsetof (allocation_object,
 186                                                   u.data));
 187     }
 188 #endif
 189
 190     static inline void*
 191     get_data (void *instance_ptr)
 192     {
 193       return (void*)(((allocation_object *) instance_ptr)->u.data);
 194     }
 195   };
 196
 197   /* Align X to 8.  */
 198   static inline size_t
 199   align_eight (size_t x)
 200   {
 201     return (((x+7) >> 3) << 3);
 202   }
 203
 204   const char *m_name;
 205   ALLOC_POOL_ID_TYPE m_id;
 206   size_t m_elts_per_block;
 207
 208   /* These are the elements that have been allocated at least once
 209      and freed.  */
 210   allocation_pool_list *m_returned_free_list;
 211
 212   /* These are the elements that have not yet been allocated out of
 213      the last block obtained from XNEWVEC.  */
 214   char* m_virgin_free_list;
 215
 216   /* The number of elements in the virgin_free_list that can be
 217      allocated before needing another block.  */
 218   size_t m_virgin_elts_remaining;
 219   /* The number of elements that are allocated.  */
 220   size_t m_elts_allocated;
 221   /* The number of elements that are released.  */
 222   size_t m_elts_free;
 223   /* The number of allocated blocks.  */
 224   size_t m_blocks_allocated;
 225   /* List of blocks that are used to allocate new objects.  */
 226   allocation_pool_list *m_block_list;
 227   /* Size of a pool elements in bytes.  */
 228   size_t m_elt_size;
 229   /* Size in bytes that should be allocated for each element.  */
 230   size_t m_size;
 231   /* Flag if a pool allocator is initialized.  */
 232   bool m_initialized;
 233   /* Memory allocation location.  */
 234   mem_location m_location;
 235 };
 236
 237 template <typename TBlockAllocator>
 238 inline
 239 base_pool_allocator <TBlockAllocator>::base_pool_allocator (
 240                                 const char *name, size_t size MEM_STAT_DECL):
 241   m_name (name), m_id (0), m_elts_per_block (0), m_returned_free_list (NULL),
 242   m_virgin_free_list (NULL), m_virgin_elts_remaining (0), m_elts_allocated (0),
 243   m_elts_free (0), m_blocks_allocated (0), m_block_list (NULL), m_size (size),
 244   m_initialized (false), m_location (ALLOC_POOL_ORIGIN, false PASS_MEM_STAT) {}
 245
 246 /* Initialize a pool allocator.  */
 247
 248 template <typename TBlockAllocator>
 249 inline void
 250 base_pool_allocator <TBlockAllocator>::initialize ()
 251 {
 252   gcc_checking_assert (!m_initialized);
 253   m_initialized = true;
 254
 255   size_t size = m_size;
 256
 257   gcc_checking_assert (m_name);
 258
 259   /* Make size large enough to store the list header.  */
 260   if (size < sizeof (allocation_pool_list*))
 261     size = sizeof (allocation_pool_list*);
 262
 263   /* Now align the size to a multiple of 8.  */
 264   size = align_eight (size);
 265
 266   /* Add the aligned size of ID.  */
 267   size += offsetof (allocation_object, u.data);
 268
 269   m_elt_size = size;
 270
 271   if (GATHER_STATISTICS)
 272     {
 273       pool_usage *u = pool_allocator_usage.register_descriptor
 274         (this, new mem_location (m_location));
 275
 276       u->m_element_size = m_elt_size;
 277       u->m_pool_name = m_name;
 278     }
 279
 280   /* List header size should be a multiple of 8.  */
 281   size_t header_size = align_eight (sizeof (allocation_pool_list));
 282
 283   m_elts_per_block = (TBlockAllocator::block_size - header_size) / size;
 284   gcc_checking_assert (m_elts_per_block != 0);
 285
 286   /* Increase the last used ID and use it for this pool.
 287      ID == 0 is used for free elements of pool so skip it.  */
 288   last_id++;
 289   if (last_id == 0)
 290     last_id++;
 291
 292   m_id = last_id;
 293 }
 294
 295 /* Free all memory allocated for the given memory pool.  */
 296 template <typename TBlockAllocator>
 297 inline void
 298 base_pool_allocator <TBlockAllocator>::release ()
 299 {
 300   if (!m_initialized)
 301     return;
 302
 303   allocation_pool_list *block, *next_block;
 304
 305   /* Free each block allocated to the pool.  */
 306   for (block = m_block_list; block != NULL; block = next_block)
 307     {
 308       next_block = block->next;
 309       TBlockAllocator::release (block);
 310     }
 311
 312   if (GATHER_STATISTICS && !after_memory_report)
 313     {
 314       pool_allocator_usage.release_instance_overhead
 315         (this, (m_elts_allocated - m_elts_free) * m_elt_size);
 316     }
 317
 318   m_returned_free_list = NULL;
 319   m_virgin_free_list = NULL;
 320   m_virgin_elts_remaining = 0;
 321   m_elts_allocated = 0;
 322   m_elts_free = 0;
 323   m_blocks_allocated = 0;
 324   m_block_list = NULL;
 325 }
 326
 327 template <typename TBlockAllocator>
 328 inline void
 329 base_pool_allocator <TBlockAllocator>::release_if_empty ()
 330 {
 331   if (m_elts_free == m_elts_allocated)
 332     release ();
 333 }
 334
 335 template <typename TBlockAllocator>
 336 inline base_pool_allocator <TBlockAllocator>::~base_pool_allocator ()
 337 {
 338   release ();
 339 }
 340
 341 /* Allocates one element from the pool specified.  */
 342 template <typename TBlockAllocator>
 343 inline void*
 344 base_pool_allocator <TBlockAllocator>::allocate ()
 345 {
 346   if (!m_initialized)
 347     initialize ();
 348
 349   allocation_pool_list *header;
 350 #ifdef ENABLE_VALGRIND_ANNOTATIONS
 351   int size;
 352 #endif
 353
 354   if (GATHER_STATISTICS)
 355     {
 356       pool_allocator_usage.register_instance_overhead (m_elt_size, this);
 357     }
 358
 359 #ifdef ENABLE_VALGRIND_ANNOTATIONS
 360   size = m_elt_size - offsetof (allocation_object, u.data);
 361 #endif
 362
 363   /* If there are no more free elements, make some more!.  */
 364   if (!m_returned_free_list)
 365     {
 366       char *block;
 367       if (!m_virgin_elts_remaining)
 368         {
 369           allocation_pool_list *block_header;
 370
 371           /* Make the block.  */
 372           block = reinterpret_cast<char *> (TBlockAllocator::allocate ());
 373           block_header = new (block) allocation_pool_list;
 374           block += align_eight (sizeof (allocation_pool_list));
 375
 376           /* Throw it on the block list.  */
 377           block_header->next = m_block_list;
 378           m_block_list = block_header;
 379
 380           /* Make the block available for allocation.  */
 381           m_virgin_free_list = block;
 382           m_virgin_elts_remaining = m_elts_per_block;
 383
 384           /* Also update the number of elements we have free/allocated, and
 385              increment the allocated block count.  */
 386           m_elts_allocated += m_elts_per_block;
 387           m_elts_free += m_elts_per_block;
 388           m_blocks_allocated += 1;
 389         }
 390
 391       /* We now know that we can take the first elt off the virgin list and
 392          put it on the returned list.  */
 393       block = m_virgin_free_list;
 394       header = (allocation_pool_list*) allocation_object::get_data (block);
 395       header->next = NULL;
 396
 397       /* Mark the element to be free.  */
 398 #if CHECKING_P
 399       ((allocation_object*) block)->id = 0;
 400 #endif
 401       VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (header,size));
 402       m_returned_free_list = header;
 403       m_virgin_free_list += m_elt_size;
 404       m_virgin_elts_remaining--;
 405
 406     }
 407
 408   /* Pull the first free element from the free list, and return it.  */
 409   header = m_returned_free_list;
 410   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_DEFINED (header, sizeof (*header)));
 411   m_returned_free_list = header->next;
 412   m_elts_free--;
 413
 414   /* Set the ID for element.  */
 415 #if CHECKING_P
 416   allocation_object::get_instance (header)->id = m_id;
 417 #endif
 418   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (header, size));
 419
 420   return (void *)(header);
 421 }
 422
 423 /* Puts PTR back on POOL's free list.  */
 424 template <typename TBlockAllocator>
 425 inline void
 426 base_pool_allocator <TBlockAllocator>::remove (void *object)
 427 {
 428   int size = m_elt_size - offsetof (allocation_object, u.data);
 429
 430   if (flag_checking)
 431     {
 432       gcc_assert (m_initialized);
 433       gcc_assert (object
 434                   /* Check if we free more than we allocated.  */
 435                   && m_elts_free < m_elts_allocated);
 436 #if CHECKING_P
 437       /* Check whether the PTR was allocated from POOL.  */
 438       gcc_assert (m_id == allocation_object::get_instance (object)->id);
 439 #endif
 440
 441       memset (object, 0xaf, size);
 442     }
 443
 444 #if CHECKING_P
 445   /* Mark the element to be free.  */
 446   allocation_object::get_instance (object)->id = 0;
 447 #endif
 448
 449   allocation_pool_list *header = new (object) allocation_pool_list;
 450   header->next = m_returned_free_list;
 451   m_returned_free_list = header;
 452   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object, size));
 453   m_elts_free++;
 454
 455   if (GATHER_STATISTICS)
 456     {
 457       pool_allocator_usage.release_instance_overhead (this, m_elt_size);
 458     }
 459 }
 460
 461 /* Number of elements currently active (not returned to pool).  Used for cheap
 462    consistency checks.  */
 463 template <typename TBlockAllocator>
 464 inline size_t
 465 base_pool_allocator <TBlockAllocator>::num_elts_current ()
 466 {
 467   return m_elts_allocated - m_elts_free;
 468 }
 469
 470 /* Specialization of base_pool_allocator which should be used in most cases.
 471    Another specialization may be needed, if object size is greater than
 472    memory_block_pool::block_size (64 KB).  */
 473 typedef base_pool_allocator <memory_block_pool> pool_allocator;
 474
 475 /* Type based memory pool allocator.  */
 476 template <typename T>
 477 class object_allocator
 478 {
 479 public:
 480   /* Default constructor for pool allocator called NAME.  */
 481   object_allocator (const char *name CXX_MEM_STAT_INFO):
 482     m_allocator (name, sizeof (T) PASS_MEM_STAT) {}
 483
 484   inline void
 485   release ()
 486   {
 487     m_allocator.release ();
 488   }
 489
 490   inline void release_if_empty ()
 491   {
 492     m_allocator.release_if_empty ();
 493   }
 494
 495
 496   /* Allocate memory for instance of type T and call a default constructor.  */
 497
 498   inline T *
 499   allocate () ATTRIBUTE_MALLOC
 500   {
 501     return ::new (m_allocator.allocate ()) T;
 502   }
 503
 504   /* Allocate memory for instance of type T and return void * that
 505      could be used in situations where a default constructor is not provided
 506      by the class T.  */
 507
 508   inline void *
 509   allocate_raw () ATTRIBUTE_MALLOC
 510   {
 511     return m_allocator.allocate ();
 512   }
 513
 514   inline void
 515   remove (T *object)
 516   {
 517     /* Call destructor.  */
 518     object->~T ();
 519
 520     m_allocator.remove (object);
 521   }
 522
 523   inline size_t
 524   num_elts_current ()
 525   {
 526     return m_allocator.num_elts_current ();
 527   }
 528
 529 private:
 530   pool_allocator m_allocator;
 531 };
 532
 533 /* Store information about each particular alloc_pool.  Note that this
 534    will underestimate the amount the amount of storage used by a small amount:
 535    1) The overhead in a pool is not accounted for.
 536    2) The unallocated elements in a block are not accounted for.  Note
 537    that this can at worst case be one element smaller that the block
 538    size for that pool.  */
 539 struct alloc_pool_descriptor
 540 {
 541   /* Number of pools allocated.  */
 542   unsigned long created;
 543   /* Gross allocated storage.  */
 544   unsigned long allocated;
 545   /* Amount of currently active storage.  */
 546   unsigned long current;
 547   /* Peak amount of storage used.  */
 548   unsigned long peak;
 549   /* Size of element in the pool.  */
 550   int elt_size;
 551 };
 552
 553 /* Helper for classes that do not provide default ctor.  */
 554
 555 template <typename T>
 556 inline void *
 557 operator new (size_t, object_allocator<T> &a)
 558 {
 559   return a.allocate_raw ();
 560 }
 561
 562 /* Hashtable mapping alloc_pool names to descriptors.  */
 563 extern hash_map<const char *, alloc_pool_descriptor> *alloc_pool_hash;
 564
 565
 566 #endif