gcc/alloc-pool.h

   1 /* Functions to support a pool of allocatable objects
   2    Copyright (C) 1997-2018 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_elt_size (0),
 244   m_size (size), m_initialized (false),
 245   m_location (ALLOC_POOL_ORIGIN, false PASS_MEM_STAT) {}
 246
 247 /* Initialize a pool allocator.  */
 248
 249 template <typename TBlockAllocator>
 250 inline void
 251 base_pool_allocator <TBlockAllocator>::initialize ()
 252 {
 253   gcc_checking_assert (!m_initialized);
 254   m_initialized = true;
 255
 256   size_t size = m_size;
 257
 258   gcc_checking_assert (m_name);
 259
 260   /* Make size large enough to store the list header.  */
 261   if (size < sizeof (allocation_pool_list*))
 262     size = sizeof (allocation_pool_list*);
 263
 264   /* Now align the size to a multiple of 8.  */
 265   size = align_eight (size);
 266
 267   /* Add the aligned size of ID.  */
 268   size += offsetof (allocation_object, u.data);
 269
 270   m_elt_size = size;
 271
 272   if (GATHER_STATISTICS)
 273     {
 274       pool_usage *u = pool_allocator_usage.register_descriptor
 275         (this, new mem_location (m_location));
 276
 277       u->m_element_size = m_elt_size;
 278       u->m_pool_name = m_name;
 279     }
 280
 281   /* List header size should be a multiple of 8.  */
 282   size_t header_size = align_eight (sizeof (allocation_pool_list));
 283
 284   m_elts_per_block = (TBlockAllocator::block_size - header_size) / size;
 285   gcc_checking_assert (m_elts_per_block != 0);
 286
 287   /* Increase the last used ID and use it for this pool.
 288      ID == 0 is used for free elements of pool so skip it.  */
 289   last_id++;
 290   if (last_id == 0)
 291     last_id++;
 292
 293   m_id = last_id;
 294 }
 295
 296 /* Free all memory allocated for the given memory pool.  */
 297 template <typename TBlockAllocator>
 298 inline void
 299 base_pool_allocator <TBlockAllocator>::release ()
 300 {
 301   if (!m_initialized)
 302     return;
 303
 304   allocation_pool_list *block, *next_block;
 305
 306   /* Free each block allocated to the pool.  */
 307   for (block = m_block_list; block != NULL; block = next_block)
 308     {
 309       next_block = block->next;
 310       TBlockAllocator::release (block);
 311     }
 312
 313   if (GATHER_STATISTICS && !after_memory_report)
 314     {
 315       pool_allocator_usage.release_instance_overhead
 316         (this, (m_elts_allocated - m_elts_free) * m_elt_size);
 317     }
 318
 319   m_returned_free_list = NULL;
 320   m_virgin_free_list = NULL;
 321   m_virgin_elts_remaining = 0;
 322   m_elts_allocated = 0;
 323   m_elts_free = 0;
 324   m_blocks_allocated = 0;
 325   m_block_list = NULL;
 326 }
 327
 328 template <typename TBlockAllocator>
 329 inline void
 330 base_pool_allocator <TBlockAllocator>::release_if_empty ()
 331 {
 332   if (m_elts_free == m_elts_allocated)
 333     release ();
 334 }
 335
 336 template <typename TBlockAllocator>
 337 inline base_pool_allocator <TBlockAllocator>::~base_pool_allocator ()
 338 {
 339   release ();
 340 }
 341
 342 /* Allocates one element from the pool specified.  */
 343 template <typename TBlockAllocator>
 344 inline void*
 345 base_pool_allocator <TBlockAllocator>::allocate ()
 346 {
 347   if (!m_initialized)
 348     initialize ();
 349
 350   allocation_pool_list *header;
 351 #ifdef ENABLE_VALGRIND_ANNOTATIONS
 352   int size;
 353 #endif
 354
 355   if (GATHER_STATISTICS)
 356     {
 357       pool_allocator_usage.register_instance_overhead (m_elt_size, this);
 358     }
 359
 360 #ifdef ENABLE_VALGRIND_ANNOTATIONS
 361   size = m_elt_size - offsetof (allocation_object, u.data);
 362 #endif
 363
 364   /* If there are no more free elements, make some more!.  */
 365   if (!m_returned_free_list)
 366     {
 367       char *block;
 368       if (!m_virgin_elts_remaining)
 369         {
 370           allocation_pool_list *block_header;
 371
 372           /* Make the block.  */
 373           block = reinterpret_cast<char *> (TBlockAllocator::allocate ());
 374           block_header = new (block) allocation_pool_list;
 375           block += align_eight (sizeof (allocation_pool_list));
 376
 377           /* Throw it on the block list.  */
 378           block_header->next = m_block_list;
 379           m_block_list = block_header;
 380
 381           /* Make the block available for allocation.  */
 382           m_virgin_free_list = block;
 383           m_virgin_elts_remaining = m_elts_per_block;
 384
 385           /* Also update the number of elements we have free/allocated, and
 386              increment the allocated block count.  */
 387           m_elts_allocated += m_elts_per_block;
 388           m_elts_free += m_elts_per_block;
 389           m_blocks_allocated += 1;
 390         }
 391
 392       /* We now know that we can take the first elt off the virgin list and
 393          put it on the returned list.  */
 394       block = m_virgin_free_list;
 395       header = (allocation_pool_list*) allocation_object::get_data (block);
 396       header->next = NULL;
 397
 398       /* Mark the element to be free.  */
 399 #if CHECKING_P
 400       ((allocation_object*) block)->id = 0;
 401 #endif
 402       VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (header,size));
 403       m_returned_free_list = header;
 404       m_virgin_free_list += m_elt_size;
 405       m_virgin_elts_remaining--;
 406
 407     }
 408
 409   /* Pull the first free element from the free list, and return it.  */
 410   header = m_returned_free_list;
 411   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_DEFINED (header, sizeof (*header)));
 412   m_returned_free_list = header->next;
 413   m_elts_free--;
 414
 415   /* Set the ID for element.  */
 416 #if CHECKING_P
 417   allocation_object::get_instance (header)->id = m_id;
 418 #endif
 419   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (header, size));
 420
 421   return (void *)(header);
 422 }
 423
 424 /* Puts PTR back on POOL's free list.  */
 425 template <typename TBlockAllocator>
 426 inline void
 427 base_pool_allocator <TBlockAllocator>::remove (void *object)
 428 {
 429   int size = m_elt_size - offsetof (allocation_object, u.data);
 430
 431   if (flag_checking)
 432     {
 433       gcc_assert (m_initialized);
 434       gcc_assert (object
 435                   /* Check if we free more than we allocated.  */
 436                   && m_elts_free < m_elts_allocated);
 437 #if CHECKING_P
 438       /* Check whether the PTR was allocated from POOL.  */
 439       gcc_assert (m_id == allocation_object::get_instance (object)->id);
 440 #endif
 441
 442       memset (object, 0xaf, size);
 443     }
 444
 445 #if CHECKING_P
 446   /* Mark the element to be free.  */
 447   allocation_object::get_instance (object)->id = 0;
 448 #endif
 449
 450   allocation_pool_list *header = new (object) allocation_pool_list;
 451   header->next = m_returned_free_list;
 452   m_returned_free_list = header;
 453   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object, size));
 454   m_elts_free++;
 455
 456   if (GATHER_STATISTICS)
 457     {
 458       pool_allocator_usage.release_instance_overhead (this, m_elt_size);
 459     }
 460 }
 461
 462 /* Number of elements currently active (not returned to pool).  Used for cheap
 463    consistency checks.  */
 464 template <typename TBlockAllocator>
 465 inline size_t
 466 base_pool_allocator <TBlockAllocator>::num_elts_current ()
 467 {
 468   return m_elts_allocated - m_elts_free;
 469 }
 470
 471 /* Specialization of base_pool_allocator which should be used in most cases.
 472    Another specialization may be needed, if object size is greater than
 473    memory_block_pool::block_size (64 KB).  */
 474 typedef base_pool_allocator <memory_block_pool> pool_allocator;
 475
 476 /* Type based memory pool allocator.  */
 477 template <typename T>
 478 class object_allocator
 479 {
 480 public:
 481   /* Default constructor for pool allocator called NAME.  */
 482   object_allocator (const char *name CXX_MEM_STAT_INFO):
 483     m_allocator (name, sizeof (T) PASS_MEM_STAT) {}
 484
 485   inline void
 486   release ()
 487   {
 488     m_allocator.release ();
 489   }
 490
 491   inline void release_if_empty ()
 492   {
 493     m_allocator.release_if_empty ();
 494   }
 495
 496
 497   /* Allocate memory for instance of type T and call a default constructor.  */
 498
 499   inline T *
 500   allocate () ATTRIBUTE_MALLOC
 501   {
 502     return ::new (m_allocator.allocate ()) T;
 503   }
 504
 505   /* Allocate memory for instance of type T and return void * that
 506      could be used in situations where a default constructor is not provided
 507      by the class T.  */
 508
 509   inline void *
 510   allocate_raw () ATTRIBUTE_MALLOC
 511   {
 512     return m_allocator.allocate ();
 513   }
 514
 515   inline void
 516   remove (T *object)
 517   {
 518     /* Call destructor.  */
 519     object->~T ();
 520
 521     m_allocator.remove (object);
 522   }
 523
 524   inline size_t
 525   num_elts_current ()
 526   {
 527     return m_allocator.num_elts_current ();
 528   }
 529
 530 private:
 531   pool_allocator m_allocator;
 532 };
 533
 534 /* Store information about each particular alloc_pool.  Note that this
 535    will underestimate the amount the amount of storage used by a small amount:
 536    1) The overhead in a pool is not accounted for.
 537    2) The unallocated elements in a block are not accounted for.  Note
 538    that this can at worst case be one element smaller that the block
 539    size for that pool.  */
 540 struct alloc_pool_descriptor
 541 {
 542   /* Number of pools allocated.  */
 543   unsigned long created;
 544   /* Gross allocated storage.  */
 545   unsigned long allocated;
 546   /* Amount of currently active storage.  */
 547   unsigned long current;
 548   /* Peak amount of storage used.  */
 549   unsigned long peak;
 550   /* Size of element in the pool.  */
 551   int elt_size;
 552 };
 553
 554 /* Helper for classes that do not provide default ctor.  */
 555
 556 template <typename T>
 557 inline void *
 558 operator new (size_t, object_allocator<T> &a)
 559 {
 560   return a.allocate_raw ();
 561 }
 562
 563 /* Hashtable mapping alloc_pool names to descriptors.  */
 564 extern hash_map<const char *, alloc_pool_descriptor> *alloc_pool_hash;
 565
 566
 567 #endif