1 /*

     2  * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 # include "incls/_precompiled.incl"

    26 # include "incls/_heap.cpp.incl"

    27 

    28 

    29 size_t CodeHeap::header_size() {

    30   return sizeof(HeapBlock);

    31 }

    32 

    33 

    34 // Implementation of Heap

    35 

    36 CodeHeap::CodeHeap() {

    37   _number_of_committed_segments = 0;

    38   _number_of_reserved_segments  = 0;

    39   _segment_size                 = 0;

    40   _log2_segment_size            = 0;

    41   _next_segment                 = 0;

    42   _freelist                     = NULL;

    43   _free_segments                = 0;

    44 }

    45 

    46 

    47 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {

    48   assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");

    49   assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");

    50   // setup _segmap pointers for faster indexing

    51   address p = (address)_segmap.low() + beg;

    52   address q = (address)_segmap.low() + end;

    53   // initialize interval

    54   while (p < q) *p++ = 0xFF;

    55 }

    56 

    57 

    58 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {

    59   assert(0   <= beg && beg <  _number_of_committed_segments, "interval begin out of bounds");

    60   assert(beg <  end && end <= _number_of_committed_segments, "interval end   out of bounds");

    61   // setup _segmap pointers for faster indexing

    62   address p = (address)_segmap.low() + beg;

    63   address q = (address)_segmap.low() + end;

    64   // initialize interval

    65   int i = 0;

    66   while (p < q) {

    67     *p++ = i++;

    68     if (i == 0xFF) i = 1;

    69   }

    70 }

    71 

    72 

    73 static size_t align_to_page_size(size_t size) {

    74   const size_t alignment = (size_t)os::vm_page_size();

    75   assert(is_power_of_2(alignment), "no kidding ???");

    76   return (size + alignment - 1) & ~(alignment - 1);

    77 }

    78 

    79 

    80 static size_t align_to_allocation_size(size_t size) {

    81   const size_t alignment = (size_t)os::vm_allocation_granularity();

    82   assert(is_power_of_2(alignment), "no kidding ???");

    83   return (size + alignment - 1) & ~(alignment - 1);

    84 }

    85 

    86 

    87 void CodeHeap::on_code_mapping(char* base, size_t size) {

    88 #ifdef LINUX

    89   extern void linux_wrap_code(char* base, size_t size);

    90   linux_wrap_code(base, size);

    91 #endif

    92 }

    93 

    94 

    95 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,

    96                        size_t segment_size) {

    97   assert(reserved_size >= committed_size, "reserved < committed");

    98   assert(segment_size >= sizeof(FreeBlock), "segment size is too small");

    99   assert(is_power_of_2(segment_size), "segment_size must be a power of 2");

   100 

   101   _segment_size      = segment_size;

   102   _log2_segment_size = exact_log2(segment_size);

   103 

   104   // Reserve and initialize space for _memory.

   105   const size_t page_size = os::page_size_for_region(committed_size,

   106                                                     reserved_size, 8);

   107   const size_t granularity = os::vm_allocation_granularity();

   108   const size_t r_align = MAX2(page_size, granularity);

   109   const size_t r_size = align_size_up(reserved_size, r_align);

   110   const size_t c_size = align_size_up(committed_size, page_size);

   111 

   112   const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :

   113     MAX2(page_size, granularity);

   114   ReservedSpace rs(r_size, rs_align, false);

   115   os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,

   116                        rs.base(), rs.size());

   117   if (!_memory.initialize(rs, c_size)) {

   118     return false;

   119   }

   120 

   121   on_code_mapping(_memory.low(), _memory.committed_size());

   122   _number_of_committed_segments = number_of_segments(_memory.committed_size());

   123   _number_of_reserved_segments  = number_of_segments(_memory.reserved_size());

   124   assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");

   125 

   126   // reserve space for _segmap

   127   if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) {

   128     return false;

   129   }

   130   assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit  enough space for segment map");

   131   assert(_segmap.reserved_size()  >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");

   132   assert(_segmap.reserved_size()  >= _segmap.committed_size()     , "just checking");

   133 

   134   // initialize remaining instance variables

   135   clear();

   136   return true;

   137 }

   138 

   139 

   140 void CodeHeap::release() {

   141   Unimplemented();

   142 }

   143 

   144 

   145 bool CodeHeap::expand_by(size_t size) {

   146   // expand _memory space

   147   size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();

   148   if (dm > 0) {

   149     char* base = _memory.low() + _memory.committed_size();

   150     if (!_memory.expand_by(dm)) return false;

   151     on_code_mapping(base, dm);

   152     size_t i = _number_of_committed_segments;

   153     _number_of_committed_segments = number_of_segments(_memory.committed_size());

   154     assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");

   155     assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");

   156     // expand _segmap space

   157     size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();

   158     if (ds > 0) {

   159       if (!_segmap.expand_by(ds)) return false;

   160     }

   161     assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");

   162     // initialize additional segmap entries

   163     mark_segmap_as_free(i, _number_of_committed_segments);

   164   }

   165   return true;

   166 }

   167 

   168 

   169 void CodeHeap::shrink_by(size_t size) {

   170   Unimplemented();

   171 }

   172 

   173 

   174 void CodeHeap::clear() {

   175   _next_segment = 0;

   176   mark_segmap_as_free(0, _number_of_committed_segments);

   177 }

   178 

   179 

   180 void* CodeHeap::allocate(size_t size) {

   181   size_t length = number_of_segments(size + sizeof(HeapBlock));

   182   assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");

   183 

   184   // First check if we can satify request from freelist

   185   debug_only(verify());

   186   HeapBlock* block = search_freelist(length);

   187   debug_only(if (VerifyCodeCacheOften) verify());

   188   if (block != NULL) {

   189     assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check");

   190     assert(!block->free(), "must be marked free");

   191 #ifdef ASSERT

   192     memset((void *)block->allocated_space(), badCodeHeapNewVal, size);

   193 #endif

   194     return block->allocated_space();

   195   }

   196 

   197   if (length < CodeCacheMinBlockLength) {

   198     length = CodeCacheMinBlockLength;

   199   }

   200   if (_next_segment + length <= _number_of_committed_segments) {

   201     mark_segmap_as_used(_next_segment, _next_segment + length);

   202     HeapBlock* b =  block_at(_next_segment);

   203     b->initialize(length);

   204     _next_segment += length;

   205 #ifdef ASSERT

   206     memset((void *)b->allocated_space(), badCodeHeapNewVal, size);

   207 #endif

   208     return b->allocated_space();

   209   } else {

   210     return NULL;

   211   }

   212 }

   213 

   214 

   215 void CodeHeap::deallocate(void* p) {

   216   assert(p == find_start(p), "illegal deallocation");

   217   // Find start of HeapBlock

   218   HeapBlock* b = (((HeapBlock *)p) - 1);

   219   assert(b->allocated_space() == p, "sanity check");

   220 #ifdef ASSERT

   221   memset((void *)b->allocated_space(),

   222          badCodeHeapFreeVal,

   223          size(b->length()) - sizeof(HeapBlock));

   224 #endif

   225   add_to_freelist(b);

   226 

   227   debug_only(if (VerifyCodeCacheOften) verify());

   228 }

   229 

   230 

   231 void* CodeHeap::find_start(void* p) const {

   232   if (!contains(p)) {

   233     return NULL;

   234   }

   235   size_t i = segment_for(p);

   236   address b = (address)_segmap.low();

   237   if (b[i] == 0xFF) {

   238     return NULL;

   239   }

   240   while (b[i] > 0) i -= (int)b[i];

   241   HeapBlock* h = block_at(i);

   242   if (h->free()) {

   243     return NULL;

   244   }

   245   return h->allocated_space();

   246 }

   247 

   248 

   249 size_t CodeHeap::alignment_unit() const {

   250   // this will be a power of two

   251   return _segment_size;

   252 }

   253 

   254 

   255 size_t CodeHeap::alignment_offset() const {

   256   // The lowest address in any allocated block will be

   257   // equal to alignment_offset (mod alignment_unit).

   258   return sizeof(HeapBlock) & (_segment_size - 1);

   259 }

   260 

   261 // Finds the next free heapblock. If the current one is free, that it returned

   262 void* CodeHeap::next_free(HeapBlock *b) const {

   263   // Since free blocks are merged, there is max. on free block

   264   // between two used ones

   265   if (b != NULL && b->free()) b = next_block(b);

   266   assert(b == NULL || !b->free(), "must be in use or at end of heap");

   267   return (b == NULL) ? NULL : b->allocated_space();

   268 }

   269 

   270 // Returns the first used HeapBlock

   271 HeapBlock* CodeHeap::first_block() const {

   272   if (_next_segment > 0)

   273     return block_at(0);

   274   return NULL;

   275 }

   276 

   277 HeapBlock *CodeHeap::block_start(void *q) const {

   278   HeapBlock* b = (HeapBlock*)find_start(q);

   279   if (b == NULL) return NULL;

   280   return b - 1;

   281 }

   282 

   283 // Returns the next Heap block an offset into one

   284 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {

   285   if (b == NULL) return NULL;

   286   size_t i = segment_for(b) + b->length();

   287   if (i < _next_segment)

   288     return block_at(i);

   289   return NULL;

   290 }

   291 

   292 

   293 // Returns current capacity

   294 size_t CodeHeap::capacity() const {

   295   return _memory.committed_size();

   296 }

   297 

   298 size_t CodeHeap::max_capacity() const {

   299   return _memory.reserved_size();

   300 }

   301 

   302 size_t CodeHeap::allocated_capacity() const {

   303   // Start with the committed size in _memory;

   304   size_t l = _memory.committed_size();

   305 

   306   // Subtract the committed, but unused, segments

   307   l -= size(_number_of_committed_segments - _next_segment);

   308 

   309   // Subtract the size of the freelist

   310   l -= size(_free_segments);

   311 

   312   return l;

   313 }

   314 

   315 // Free list management

   316 

   317 FreeBlock *CodeHeap::following_block(FreeBlock *b) {

   318   return (FreeBlock*)(((address)b) + _segment_size * b->length());

   319 }

   320 

   321 // Inserts block b after a

   322 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {

   323   assert(a != NULL && b != NULL, "must be real pointers");

   324 

   325   // Link b into the list after a

   326   b->set_link(a->link());

   327   a->set_link(b);

   328 

   329   // See if we can merge blocks

   330   merge_right(b); // Try to make b bigger

   331   merge_right(a); // Try to make a include b

   332 }

   333 

   334 // Try to merge this block with the following block

   335 void CodeHeap::merge_right(FreeBlock *a) {

   336   assert(a->free(), "must be a free block");

   337   if (following_block(a) == a->link()) {

   338     assert(a->link() != NULL && a->link()->free(), "must be free too");

   339     // Update block a to include the following block

   340     a->set_length(a->length() + a->link()->length());

   341     a->set_link(a->link()->link());

   342     // Update find_start map

   343     size_t beg = segment_for(a);

   344     mark_segmap_as_used(beg, beg + a->length());

   345   }

   346 }

   347 

   348 void CodeHeap::add_to_freelist(HeapBlock *a) {

   349   FreeBlock* b = (FreeBlock*)a;

   350   assert(b != _freelist, "cannot be removed twice");

   351 

   352   // Mark as free and update free space count

   353   _free_segments += b->length();

   354   b->set_free();

   355 

   356   // First element in list?

   357   if (_freelist == NULL) {

   358     _freelist = b;

   359     b->set_link(NULL);

   360     return;

   361   }

   362 

   363   // Scan for right place to put into list. List

   364   // is sorted by increasing addresseses

   365   FreeBlock* prev = NULL;

   366   FreeBlock* cur  = _freelist;

   367   while(cur != NULL && cur < b) {

   368     assert(prev == NULL || prev < cur, "must be ordered");

   369     prev = cur;

   370     cur  = cur->link();

   371   }

   372 

   373   assert( (prev == NULL && b < _freelist) ||

   374           (prev < b && (cur == NULL || b < cur)), "list must be ordered");

   375 

   376   if (prev == NULL) {

   377     // Insert first in list

   378     b->set_link(_freelist);

   379     _freelist = b;

   380     merge_right(_freelist);

   381   } else {

   382     insert_after(prev, b);

   383   }

   384 }

   385 

   386 // Search freelist for an entry on the list with the best fit

   387 // Return NULL if no one was found

   388 FreeBlock* CodeHeap::search_freelist(size_t length) {

   389   FreeBlock *best_block = NULL;

   390   FreeBlock *best_prev  = NULL;

   391   size_t best_length = 0;

   392 

   393   // Search for smallest block which is bigger than length

   394   FreeBlock *prev = NULL;

   395   FreeBlock *cur = _freelist;

   396   while(cur != NULL) {

   397     size_t l = cur->length();

   398     if (l >= length && (best_block == NULL || best_length > l)) {

   399       // Remember best block, its previous element, and its length

   400       best_block = cur;

   401       best_prev  = prev;

   402       best_length = best_block->length();

   403     }

   404 

   405     // Next element in list

   406     prev = cur;

   407     cur  = cur->link();

   408   }

   409 

   410   if (best_block == NULL) {

   411     // None found

   412     return NULL;

   413   }

   414 

   415   assert((best_prev == NULL && _freelist == best_block ) ||

   416          (best_prev != NULL && best_prev->link() == best_block), "sanity check");

   417 

   418   // Exact (or at least good enough) fit. Remove from list.

   419   // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.

   420   if (best_length < length + CodeCacheMinBlockLength) {

   421     length = best_length;

   422     if (best_prev == NULL) {

   423       assert(_freelist == best_block, "sanity check");

   424       _freelist = _freelist->link();

   425     } else {

   426       // Unmap element

   427       best_prev->set_link(best_block->link());

   428     }

   429   } else {

   430     // Truncate block and return a pointer to the following block

   431     best_block->set_length(best_length - length);

   432     best_block = following_block(best_block);

   433     // Set used bit and length on new block

   434     size_t beg = segment_for(best_block);

   435     mark_segmap_as_used(beg, beg + length);

   436     best_block->set_length(length);

   437   }

   438 

   439   best_block->set_used();

   440   _free_segments -= length;

   441   return best_block;

   442 }

   443 

   444 //----------------------------------------------------------------------------

   445 // Non-product code

   446 

   447 #ifndef PRODUCT

   448 

   449 void CodeHeap::print() {

   450   tty->print_cr("The Heap");

   451 }

   452 

   453 #endif

   454 

   455 void CodeHeap::verify() {

   456   // Count the number of blocks on the freelist, and the amount of space

   457   // represented.

   458   int count = 0;

   459   size_t len = 0;

   460   for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {

   461     len += b->length();

   462     count++;

   463   }

   464 

   465   // Verify that freelist contains the right amount of free space

   466   guarantee(len == _free_segments, "wrong freelist");

   467 

   468   // Verify that the number of free blocks is not out of hand.

   469   static int free_block_threshold = 10000;

   470   if (count > free_block_threshold) {

   471     warning("CodeHeap: # of free blocks > %d", free_block_threshold);

   472     // Double the warning limit

   473     free_block_threshold *= 2;

   474   }

   475 

   476   // Verify that the freelist contains the same number of free blocks that is

   477   // found on the full list.

   478   for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {

   479     if (h->free()) count--;

   480   }

   481   guarantee(count == 0, "missing free blocks");

   482 }