Mercurial > hg > truffle
view src/share/vm/memory/heap.hpp @ 20304:a22acf6d7598
8048112: G1 Full GC needs to support the case when the very first region is not available
Summary: Refactor preparation for compaction during Full GC so that it lazily initializes the first compaction point. This also avoids problems later when the first region may not be committed. Also reviewed by K. Barrett.
Reviewed-by: brutisso
author | tschatzl |
---|---|
date | Mon, 21 Jul 2014 10:00:31 +0200 |
parents | 55fb97c4c58d |
children | 63a4eb8bcd23 |
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/* * Copyright (c) 1997, 2013, 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. * */ #ifndef SHARE_VM_MEMORY_HEAP_HPP #define SHARE_VM_MEMORY_HEAP_HPP #include "memory/allocation.hpp" #include "runtime/virtualspace.hpp" // Blocks class HeapBlock VALUE_OBJ_CLASS_SPEC { friend class VMStructs; public: struct Header { size_t _length; // the length in segments bool _used; // Used bit }; protected: union { Header _header; int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ]; // pad to 0 mod 8 }; public: // Initialization void initialize(size_t length) { _header._length = length; set_used(); } // Accessors void* allocated_space() const { return (void*)(this + 1); } size_t length() const { return _header._length; } // Used/free void set_used() { _header._used = true; } void set_free() { _header._used = false; } bool free() { return !_header._used; } }; class FreeBlock: public HeapBlock { friend class VMStructs; protected: FreeBlock* _link; public: // Initialization void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; } // Merging void set_length(size_t l) { _header._length = l; } // Accessors FreeBlock* link() const { return _link; } void set_link(FreeBlock* link) { _link = link; } }; class CodeHeap : public CHeapObj<mtCode> { friend class VMStructs; private: VirtualSpace _memory; // the memory holding the blocks VirtualSpace _segmap; // the memory holding the segment map size_t _number_of_committed_segments; size_t _number_of_reserved_segments; size_t _segment_size; int _log2_segment_size; size_t _next_segment; FreeBlock* _freelist; size_t _freelist_segments; // No. of segments in freelist // Helper functions size_t size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; } size_t segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; } size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; } HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); } void mark_segmap_as_free(size_t beg, size_t end); void mark_segmap_as_used(size_t beg, size_t end); // Freelist management helpers FreeBlock* following_block(FreeBlock *b); void insert_after(FreeBlock* a, FreeBlock* b); void merge_right (FreeBlock* a); // Toplevel freelist management void add_to_freelist(HeapBlock *b); FreeBlock* search_freelist(size_t length, bool is_critical); // Iteration helpers void* next_free(HeapBlock* b) const; HeapBlock* first_block() const; HeapBlock* next_block(HeapBlock* b) const; HeapBlock* block_start(void* p) const; // to perform additional actions on creation of executable code void on_code_mapping(char* base, size_t size); public: CodeHeap(); // Heap extents bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size); void release(); // releases all allocated memory bool expand_by(size_t size); // expands commited memory by size void shrink_by(size_t size); // shrinks commited memory by size void clear(); // clears all heap contents // Memory allocation void* allocate (size_t size, bool is_critical); // allocates a block of size or returns NULL void deallocate(void* p); // deallocates a block // Attributes char* low_boundary() const { return _memory.low_boundary (); } char* high() const { return _memory.high(); } char* high_boundary() const { return _memory.high_boundary(); } bool contains(const void* p) const { return low_boundary() <= p && p < high(); } void* find_start(void* p) const; // returns the block containing p or NULL size_t alignment_unit() const; // alignment of any block size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit static size_t header_size(); // returns the header size for each heap block // Iteration // returns the first block or NULL void* first() const { return next_free(first_block()); } // returns the next block given a block p or NULL void* next(void* p) const { return next_free(next_block(block_start(p))); } // Statistics size_t capacity() const; size_t max_capacity() const; size_t allocated_capacity() const; size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); } private: size_t heap_unallocated_capacity() const; public: // Debugging void verify(); void print() PRODUCT_RETURN; }; #endif // SHARE_VM_MEMORY_HEAP_HPP