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 /*

  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.

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

  *

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

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

  * published by the Free Software Foundation.

  *

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

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

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

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

  * accompanied this code).

  *

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

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

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

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 #include "precompiled.hpp"

 #include "memory/heap.hpp"

 #include "oops/oop.inline.hpp"

 #include "runtime/os.hpp"

 size_t CodeHeap::header_size() {

   return sizeof(HeapBlock);

 }

 // Implementation of Heap

 CodeHeap::CodeHeap() {

   _number_of_committed_segments = 0;

   _number_of_reserved_segments  = 0;

   _segment_size                 = 0;

   _log2_segment_size            = 0;

   _next_segment                 = 0;

   _freelist                     = NULL;

   _free_segments                = 0;

 }

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

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

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

   // setup _segmap pointers for faster indexing

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

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

   // initialize interval

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

 }

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

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

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

   // setup _segmap pointers for faster indexing

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

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

   // initialize interval

   int i = 0;

   while (p < q) {

     *p++ = i++;

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

   }

 }

 static size_t align_to_page_size(size_t size) {

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

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

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

 }

 static size_t align_to_allocation_size(size_t size) {

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

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

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

 }

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

 #ifdef LINUX

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

   linux_wrap_code(base, size);

 #endif

 }

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

                        size_t segment_size) {

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

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

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

   _segment_size      = segment_size;

   _log2_segment_size = exact_log2(segment_size);

   // Reserve and initialize space for _memory.

   const size_t page_size = os::can_execute_large_page_memory() ?

           os::page_size_for_region(committed_size, reserved_size, 8) :

           os::vm_page_size();

   const size_t granularity = os::vm_allocation_granularity();

   const size_t r_align = MAX2(page_size, granularity);

   const size_t r_size = align_size_up(reserved_size, r_align);

   const size_t c_size = align_size_up(committed_size, page_size);

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

     MAX2(page_size, granularity);

   ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);

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

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

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

     return false;

   }

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

   _number_of_committed_segments = number_of_segments(_memory.committed_size());

   _number_of_reserved_segments  = number_of_segments(_memory.reserved_size());

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

   // reserve space for _segmap

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

     return false;

   }

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

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

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

   // initialize remaining instance variables

   clear();

   return true;

 }

 void CodeHeap::release() {

   Unimplemented();

 }

 bool CodeHeap::expand_by(size_t size) {

   // expand _memory space

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

   if (dm > 0) {

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

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

     on_code_mapping(base, dm);

     size_t i = _number_of_committed_segments;

     _number_of_committed_segments = number_of_segments(_memory.committed_size());

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

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

     // expand _segmap space

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

     if (ds > 0) {

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

     }

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

     // initialize additional segmap entries

     mark_segmap_as_free(i, _number_of_committed_segments);

   }

   return true;

 }

 void CodeHeap::shrink_by(size_t size) {

   Unimplemented();

 }

 void CodeHeap::clear() {

   _next_segment = 0;

   mark_segmap_as_free(0, _number_of_committed_segments);

 }

 void* CodeHeap::allocate(size_t size) {

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

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

   // First check if we can satify request from freelist

   debug_only(verify());

   HeapBlock* block = search_freelist(length);

   debug_only(if (VerifyCodeCacheOften) verify());

   if (block != NULL) {

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

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

 #ifdef ASSERT

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

 #endif

     return block->allocated_space();

   }

   if (length < CodeCacheMinBlockLength) {

     length = CodeCacheMinBlockLength;

   }

   if (_next_segment + length <= _number_of_committed_segments) {

     mark_segmap_as_used(_next_segment, _next_segment + length);

     HeapBlock* b =  block_at(_next_segment);

     b->initialize(length);

     _next_segment += length;

 #ifdef ASSERT

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

 #endif

     return b->allocated_space();

   } else {

     return NULL;

   }

 }

 void CodeHeap::deallocate(void* p) {

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

   // Find start of HeapBlock

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

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

 #ifdef ASSERT

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

          badCodeHeapFreeVal,

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

 #endif

   add_to_freelist(b);

   debug_only(if (VerifyCodeCacheOften) verify());

 }

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

   if (!contains(p)) {

     return NULL;

   }

   size_t i = segment_for(p);

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

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

     return NULL;

   }

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

   HeapBlock* h = block_at(i);

   if (h->free()) {

     return NULL;

   }

   return h->allocated_space();

 }

 size_t CodeHeap::alignment_unit() const {

   // this will be a power of two

   return _segment_size;

 }

 size_t CodeHeap::alignment_offset() const {

   // The lowest address in any allocated block will be

   // equal to alignment_offset (mod alignment_unit).

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

 }

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

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

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

   // between two used ones

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

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

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

 }

 // Returns the first used HeapBlock

 HeapBlock* CodeHeap::first_block() const {

   if (_next_segment > 0)

     return block_at(0);

   return NULL;

 }

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

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

   if (b == NULL) return NULL;

   return b - 1;

 }

 // Returns the next Heap block an offset into one

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

   if (b == NULL) return NULL;

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

   if (i < _next_segment)

     return block_at(i);

   return NULL;

 }

 // Returns current capacity

 size_t CodeHeap::capacity() const {

   return _memory.committed_size();

 }

 size_t CodeHeap::max_capacity() const {

   return _memory.reserved_size();

 }

 size_t CodeHeap::allocated_capacity() const {

   // Start with the committed size in _memory;

   size_t l = _memory.committed_size();

   // Subtract the committed, but unused, segments

   l -= size(_number_of_committed_segments - _next_segment);

   // Subtract the size of the freelist

   l -= size(_free_segments);

   return l;

 }

 size_t CodeHeap::largest_free_block() const {

   // First check unused space excluding free blocks.

   size_t free_sz = size(_free_segments);

   size_t unused  = max_capacity() - allocated_capacity() - free_sz;

   if (unused >= free_sz)

     return unused;

   // Now check largest free block.

   size_t len = 0;

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

     if (b->length() > len)

       len = b->length();

   }

   return MAX2(unused, size(len));

 }

 // Free list management

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

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

 }

 // Inserts block b after a

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

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

   // Link b into the list after a

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

   a->set_link(b);

   // See if we can merge blocks

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

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

 }

 // Try to merge this block with the following block

 void CodeHeap::merge_right(FreeBlock *a) {

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

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

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

     // Update block a to include the following block

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

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

     // Update find_start map

     size_t beg = segment_for(a);

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

   }

 }

 void CodeHeap::add_to_freelist(HeapBlock *a) {

   FreeBlock* b = (FreeBlock*)a;

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

   // Mark as free and update free space count

   _free_segments += b->length();

   b->set_free();

   // First element in list?

   if (_freelist == NULL) {

     _freelist = b;

     b->set_link(NULL);

     return;

   }

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

   // is sorted by increasing addresseses

   FreeBlock* prev = NULL;

   FreeBlock* cur  = _freelist;

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

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

     prev = cur;

     cur  = cur->link();

   }

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

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

   if (prev == NULL) {

     // Insert first in list

     b->set_link(_freelist);

     _freelist = b;

     merge_right(_freelist);

   } else {

     insert_after(prev, b);

   }

 }

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

 // Return NULL if no one was found

 FreeBlock* CodeHeap::search_freelist(size_t length) {

   FreeBlock *best_block = NULL;

   FreeBlock *best_prev  = NULL;

   size_t best_length = 0;

   // Search for smallest block which is bigger than length

   FreeBlock *prev = NULL;

   FreeBlock *cur = _freelist;

   while(cur != NULL) {

     size_t l = cur->length();

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

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

       best_block = cur;

       best_prev  = prev;

       best_length = best_block->length();

     }

     // Next element in list

     prev = cur;

     cur  = cur->link();

   }

   if (best_block == NULL) {

     // None found

     return NULL;

   }

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

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

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

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

   if (best_length < length + CodeCacheMinBlockLength) {

     length = best_length;

     if (best_prev == NULL) {

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

       _freelist = _freelist->link();

     } else {

       // Unmap element

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

     }

   } else {

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

     best_block->set_length(best_length - length);

     best_block = following_block(best_block);

     // Set used bit and length on new block

     size_t beg = segment_for(best_block);

     mark_segmap_as_used(beg, beg + length);

     best_block->set_length(length);

   }

   best_block->set_used();

   _free_segments -= length;

   return best_block;

 }

 //----------------------------------------------------------------------------

 // Non-product code

 #ifndef PRODUCT

 void CodeHeap::print() {

   tty->print_cr("The Heap");

 }

 #endif

 void CodeHeap::verify() {

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

   // represented.

   int count = 0;

   size_t len = 0;

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

     len += b->length();

     count++;

   }

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

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

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

   static int free_block_threshold = 10000;

   if (count > free_block_threshold) {

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

     // Double the warning limit

     free_block_threshold *= 2;

   }

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

   // found on the full list.

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

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

   }

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

 }