gcc/alloc-pool.h

   1 /* Functions to support a pool of allocatable objects
   2    Copyright (C) 1997-2019 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 " PRsa(5) PRsa(9) ":%5.1f%%"
  67              PRsa(9) PRsa(9) ":%5.1f%%%12" PRIu64 "\n",
  68              m_pool_name, location_string,
  69              SIZE_AMOUNT (m_instances),
  70              SIZE_AMOUNT (m_allocated),
  71              get_percent (m_allocated, total.m_allocated),
  72              SIZE_AMOUNT (m_peak),
  73              SIZE_AMOUNT (m_times),
  74              get_percent (m_times, total.m_times),
  75              (uint64_t)m_element_size);
  76
  77     free (location_string);
  78   }
  79
  80   /* Dump header with NAME.  */
  81   static inline void
  82   dump_header (const char *name)
  83   {
  84     fprintf (stderr, "%-32s%-48s %6s%11s%16s%17s%12s\n", "Pool name", name,
  85              "Pools", "Leak", "Peak", "Times", "Elt size");
  86   }
  87
  88   /* Dump footer.  */
  89   inline void
  90   dump_footer ()
  91   {
  92     fprintf (stderr, "%s" PRsa(82) PRsa(10) "\n", "Total",
  93              SIZE_AMOUNT (m_instances), SIZE_AMOUNT (m_allocated));
  94   }
  95
  96   /* Element size.  */
  97   size_t m_element_size;
  98   /* Pool name.  */
  99   const char *m_pool_name;
 100 };
 101
 102 extern mem_alloc_description<pool_usage> pool_allocator_usage;
 103
 104 #if 0
 105 /* If a pool with custom block size is needed, one might use the following
 106    template.  An instance of this template can be used as a parameter for
 107    instantiating base_pool_allocator template:
 108
 109         typedef custom_block_allocator <128*1024> huge_block_allocator;
 110         ...
 111         static base_pool_allocator <huge_block_allocator>
 112                                                 value_pool ("value", 16384);
 113
 114    Right now it's not used anywhere in the code, and is given here as an
 115    example).  */
 116
 117 template <size_t BlockSize>
 118 class custom_block_allocator
 119 {
 120 public:
 121   static const size_t block_size = BlockSize;
 122
 123   static inline void *
 124   allocate () ATTRIBUTE_MALLOC
 125   {
 126     return XNEWVEC (char, BlockSize);
 127   }
 128
 129   static inline void
 130   release (void *block)
 131   {
 132     XDELETEVEC (block);
 133   }
 134 };
 135 #endif
 136
 137 /* Generic pool allocator.  */
 138
 139 template <typename TBlockAllocator>
 140 class base_pool_allocator
 141 {
 142 public:
 143   /* Default constructor for pool allocator called NAME.  */
 144   base_pool_allocator (const char *name, size_t size CXX_MEM_STAT_INFO);
 145   ~base_pool_allocator ();
 146   void release ();
 147   void release_if_empty ();
 148   void *allocate () ATTRIBUTE_MALLOC;
 149   void remove (void *object);
 150   size_t num_elts_current ();
 151
 152 private:
 153   struct allocation_pool_list
 154   {
 155     allocation_pool_list *next;
 156   };
 157
 158   /* Initialize a pool allocator.  */
 159   void initialize ();
 160
 161   struct allocation_object
 162   {
 163 #if CHECKING_P
 164     /* The ID of alloc pool which the object was allocated from.  */
 165     ALLOC_POOL_ID_TYPE id;
 166 #endif
 167
 168     union
 169       {
 170         /* The data of the object.  */
 171         char data[1];
 172
 173         /* Because we want any type of data to be well aligned after the ID,
 174            the following elements are here.  They are never accessed so
 175            the allocated object may be even smaller than this structure.
 176            We do not care about alignment for floating-point types.  */
 177         char *align_p;
 178         int64_t align_i;
 179       } u;
 180
 181 #if CHECKING_P
 182     static inline allocation_object*
 183     get_instance (void *data_ptr)
 184     {
 185       return (allocation_object *)(((char *)(data_ptr))
 186                                       - offsetof (allocation_object,
 187                                                   u.data));
 188     }
 189 #endif
 190
 191     static inline void*
 192     get_data (void *instance_ptr)
 193     {
 194       return (void*)(((allocation_object *) instance_ptr)->u.data);
 195     }
 196   };
 197
 198   /* Align X to 8.  */
 199   static inline size_t
 200   align_eight (size_t x)
 201   {
 202     return (((x+7) >> 3) << 3);
 203   }
 204
 205   const char *m_name;
 206   ALLOC_POOL_ID_TYPE m_id;
 207   size_t m_elts_per_block;
 208
 209   /* These are the elements that have been allocated at least once
 210      and freed.  */
 211   allocation_pool_list *m_returned_free_list;
 212
 213   /* These are the elements that have not yet been allocated out of
 214      the last block obtained from XNEWVEC.  */
 215   char* m_virgin_free_list;
 216
 217   /* The number of elements in the virgin_free_list that can be
 218      allocated before needing another block.  */
 219   size_t m_virgin_elts_remaining;
 220   /* The number of elements that are allocated.  */
 221   size_t m_elts_allocated;
 222   /* The number of elements that are released.  */
 223   size_t m_elts_free;
 224   /* The number of allocated blocks.  */
 225   size_t m_blocks_allocated;
 226   /* List of blocks that are used to allocate new objects.  */
 227   allocation_pool_list *m_block_list;
 228   /* Size of a pool elements in bytes.  */
 229   size_t m_elt_size;
 230   /* Size in bytes that should be allocated for each element.  */
 231   size_t m_size;
 232   /* Flag if a pool allocator is initialized.  */
 233   bool m_initialized;
 234   /* Memory allocation location.  */
 235   mem_location m_location;
 236 };
 237
 238 template <typename TBlockAllocator>
 239 inline
 240 base_pool_allocator <TBlockAllocator>::base_pool_allocator (
 241                                 const char *name, size_t size MEM_STAT_DECL):
 242   m_name (name), m_id (0), m_elts_per_block (0), m_returned_free_list (NULL),
 243   m_virgin_free_list (NULL), m_virgin_elts_remaining (0), m_elts_allocated (0),
 244   m_elts_free (0), m_blocks_allocated (0), m_block_list (NULL), m_elt_size (0),
 245   m_size (size), m_initialized (false),
 246   m_location (ALLOC_POOL_ORIGIN, false PASS_MEM_STAT) {}
 247
 248 /* Initialize a pool allocator.  */
 249
 250 template <typename TBlockAllocator>
 251 inline void
 252 base_pool_allocator <TBlockAllocator>::initialize ()
 253 {
 254   gcc_checking_assert (!m_initialized);
 255   m_initialized = true;
 256
 257   size_t size = m_size;
 258
 259   gcc_checking_assert (m_name);
 260   gcc_checking_assert (m_size);
 261
 262   /* Make size large enough to store the list header.  */
 263   if (size < sizeof (allocation_pool_list*))
 264     size = sizeof (allocation_pool_list*);
 265
 266   /* Now align the size to a multiple of 8.  */
 267   size = align_eight (size);
 268
 269   /* Add the aligned size of ID.  */
 270   size += offsetof (allocation_object, u.data);
 271
 272   m_elt_size = size;
 273
 274   if (GATHER_STATISTICS)
 275     {
 276       pool_usage *u = pool_allocator_usage.register_descriptor
 277         (this, new mem_location (m_location));
 278
 279       u->m_element_size = m_elt_size;
 280       u->m_pool_name = m_name;
 281     }
 282
 283   /* List header size should be a multiple of 8.  */
 284   size_t header_size = align_eight (sizeof (allocation_pool_list));
 285
 286   m_elts_per_block = (TBlockAllocator::block_size - header_size) / size;
 287   gcc_checking_assert (m_elts_per_block != 0);
 288
 289   /* Increase the last used ID and use it for this pool.
 290      ID == 0 is used for free elements of pool so skip it.  */
 291   last_id++;
 292   if (last_id == 0)
 293     last_id++;
 294
 295   m_id = last_id;
 296 }
 297
 298 /* Free all memory allocated for the given memory pool.  */
 299 template <typename TBlockAllocator>
 300 inline void
 301 base_pool_allocator <TBlockAllocator>::release ()
 302 {
 303   if (!m_initialized)
 304     return;
 305
 306   allocation_pool_list *block, *next_block;
 307
 308   /* Free each block allocated to the pool.  */
 309   for (block = m_block_list; block != NULL; block = next_block)
 310     {
 311       next_block = block->next;
 312       TBlockAllocator::release (block);
 313     }
 314
 315   if (GATHER_STATISTICS && !after_memory_report)
 316     {
 317       pool_allocator_usage.release_instance_overhead
 318         (this, (m_elts_allocated - m_elts_free) * m_elt_size);
 319     }
 320
 321   m_returned_free_list = NULL;
 322   m_virgin_free_list = NULL;
 323   m_virgin_elts_remaining = 0;
 324   m_elts_allocated = 0;
 325   m_elts_free = 0;
 326   m_blocks_allocated = 0;
 327   m_block_list = NULL;
 328 }
 329
 330 template <typename TBlockAllocator>
 331 inline void
 332 base_pool_allocator <TBlockAllocator>::release_if_empty ()
 333 {
 334   if (m_elts_free == m_elts_allocated)
 335     release ();
 336 }
 337
 338 template <typename TBlockAllocator>
 339 inline base_pool_allocator <TBlockAllocator>::~base_pool_allocator ()
 340 {
 341   release ();
 342 }
 343
 344 /* Allocates one element from the pool specified.  */
 345 template <typename TBlockAllocator>
 346 inline void*
 347 base_pool_allocator <TBlockAllocator>::allocate ()
 348 {
 349   if (!m_initialized)
 350     initialize ();
 351
 352   allocation_pool_list *header;
 353 #ifdef ENABLE_VALGRIND_ANNOTATIONS
 354   int size;
 355 #endif
 356
 357   if (GATHER_STATISTICS)
 358     {
 359       pool_allocator_usage.register_instance_overhead (m_elt_size, this);
 360     }
 361
 362 #ifdef ENABLE_VALGRIND_ANNOTATIONS
 363   size = m_elt_size - offsetof (allocation_object, u.data);
 364 #endif
 365
 366   /* If there are no more free elements, make some more!.  */
 367   if (!m_returned_free_list)
 368     {
 369       char *block;
 370       if (!m_virgin_elts_remaining)
 371         {
 372           allocation_pool_list *block_header;
 373
 374           /* Make the block.  */
 375           block = reinterpret_cast<char *> (TBlockAllocator::allocate ());
 376           block_header = new (block) allocation_pool_list;
 377           block += align_eight (sizeof (allocation_pool_list));
 378
 379           /* Throw it on the block list.  */
 380           block_header->next = m_block_list;
 381           m_block_list = block_header;
 382
 383           /* Make the block available for allocation.  */
 384           m_virgin_free_list = block;
 385           m_virgin_elts_remaining = m_elts_per_block;
 386
 387           /* Also update the number of elements we have free/allocated, and
 388              increment the allocated block count.  */
 389           m_elts_allocated += m_elts_per_block;
 390           m_elts_free += m_elts_per_block;
 391           m_blocks_allocated += 1;
 392         }
 393
 394       /* We now know that we can take the first elt off the virgin list and
 395          put it on the returned list.  */
 396       block = m_virgin_free_list;
 397       header = (allocation_pool_list*) allocation_object::get_data (block);
 398       header->next = NULL;
 399
 400       /* Mark the element to be free.  */
 401 #if CHECKING_P
 402       ((allocation_object*) block)->id = 0;
 403 #endif
 404       VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (header,size));
 405       m_returned_free_list = header;
 406       m_virgin_free_list += m_elt_size;
 407       m_virgin_elts_remaining--;
 408
 409     }
 410
 411   /* Pull the first free element from the free list, and return it.  */
 412   header = m_returned_free_list;
 413   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_DEFINED (header, sizeof (*header)));
 414   m_returned_free_list = header->next;
 415   m_elts_free--;
 416
 417   /* Set the ID for element.  */
 418 #if CHECKING_P
 419   allocation_object::get_instance (header)->id = m_id;
 420 #endif
 421   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (header, size));
 422
 423   return (void *)(header);
 424 }
 425
 426 /* Puts PTR back on POOL's free list.  */
 427 template <typename TBlockAllocator>
 428 inline void
 429 base_pool_allocator <TBlockAllocator>::remove (void *object)
 430 {
 431   int size = m_elt_size - offsetof (allocation_object, u.data);
 432
 433   if (flag_checking)
 434     {
 435       gcc_assert (m_initialized);
 436       gcc_assert (object
 437                   /* Check if we free more than we allocated.  */
 438                   && m_elts_free < m_elts_allocated);
 439 #if CHECKING_P
 440       /* Check whether the PTR was allocated from POOL.  */
 441       gcc_assert (m_id == allocation_object::get_instance (object)->id);
 442 #endif
 443
 444       memset (object, 0xaf, size);
 445     }
 446
 447 #if CHECKING_P
 448   /* Mark the element to be free.  */
 449   allocation_object::get_instance (object)->id = 0;
 450 #endif
 451
 452   allocation_pool_list *header = new (object) allocation_pool_list;
 453   header->next = m_returned_free_list;
 454   m_returned_free_list = header;
 455   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object, size));
 456   m_elts_free++;
 457
 458   if (GATHER_STATISTICS)
 459     {
 460       pool_allocator_usage.release_instance_overhead (this, m_elt_size);
 461     }
 462 }
 463
 464 /* Number of elements currently active (not returned to pool).  Used for cheap
 465    consistency checks.  */
 466 template <typename TBlockAllocator>
 467 inline size_t
 468 base_pool_allocator <TBlockAllocator>::num_elts_current ()
 469 {
 470   return m_elts_allocated - m_elts_free;
 471 }
 472
 473 /* Specialization of base_pool_allocator which should be used in most cases.
 474    Another specialization may be needed, if object size is greater than
 475    memory_block_pool::block_size (64 KB).  */
 476 typedef base_pool_allocator <memory_block_pool> pool_allocator;
 477
 478 /* Type based memory pool allocator.  */
 479 template <typename T>
 480 class object_allocator
 481 {
 482 public:
 483   /* Default constructor for pool allocator called NAME.  */
 484   object_allocator (const char *name CXX_MEM_STAT_INFO):
 485     m_allocator (name, sizeof (T) PASS_MEM_STAT) {}
 486
 487   inline void
 488   release ()
 489   {
 490     m_allocator.release ();
 491   }
 492
 493   inline void release_if_empty ()
 494   {
 495     m_allocator.release_if_empty ();
 496   }
 497
 498
 499   /* Allocate memory for instance of type T and call a default constructor.  */
 500
 501   inline T *
 502   allocate () ATTRIBUTE_MALLOC
 503   {
 504     return ::new (m_allocator.allocate ()) T;
 505   }
 506
 507   /* Allocate memory for instance of type T and return void * that
 508      could be used in situations where a default constructor is not provided
 509      by the class T.  */
 510
 511   inline void *
 512   allocate_raw () ATTRIBUTE_MALLOC
 513   {
 514     return m_allocator.allocate ();
 515   }
 516
 517   inline void
 518   remove (T *object)
 519   {
 520     /* Call destructor.  */
 521     object->~T ();
 522
 523     m_allocator.remove (object);
 524   }
 525
 526   inline size_t
 527   num_elts_current ()
 528   {
 529     return m_allocator.num_elts_current ();
 530   }
 531
 532 private:
 533   pool_allocator m_allocator;
 534 };
 535
 536 /* Store information about each particular alloc_pool.  Note that this
 537    will underestimate the amount the amount of storage used by a small amount:
 538    1) The overhead in a pool is not accounted for.
 539    2) The unallocated elements in a block are not accounted for.  Note
 540    that this can at worst case be one element smaller that the block
 541    size for that pool.  */
 542 struct alloc_pool_descriptor
 543 {
 544   /* Number of pools allocated.  */
 545   unsigned long created;
 546   /* Gross allocated storage.  */
 547   unsigned long allocated;
 548   /* Amount of currently active storage.  */
 549   unsigned long current;
 550   /* Peak amount of storage used.  */
 551   unsigned long peak;
 552   /* Size of element in the pool.  */
 553   int elt_size;
 554 };
 555
 556 /* Helper for classes that do not provide default ctor.  */
 557
 558 template <typename T>
 559 inline void *
 560 operator new (size_t, object_allocator<T> &a)
 561 {
 562   return a.allocate_raw ();
 563 }
 564
 565 /* Hashtable mapping alloc_pool names to descriptors.  */
 566 extern hash_map<const char *, alloc_pool_descriptor> *alloc_pool_hash;
 567
 568
 569 #endif