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src/share/vm/interpreter/oopMapCache.hpp@c7ec737733a6 (annotated)

src/share/vm/interpreter/oopMapCache.hpp

Thu, 30 Oct 2008 15:48:59 -0400

author

kamg

date

Thu, 30 Oct 2008 15:48:59 -0400

changeset 848

c7ec737733a6

parent 435

a61af66fc99e

child 1907

c18cbe5936b8

permissions

-rw-r--r--

6756528: Bytecodes::special_length_at reads past end of code buffer
Summary: Add end-of-buffer indicator for paths used by the verifier
Reviewed-by: acorn, coleenp

duke@435	1	/*
duke@435	2	* Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	// A Cache for storing (method, bci) -> oopMap.
duke@435	26	// The memory management system uses the cache when locating object
duke@435	27	// references in an interpreted frame.
duke@435	28	//
duke@435	29	// OopMapCache's are allocated lazily per instanceKlass.
duke@435	30
duke@435	31	// The oopMap (InterpreterOopMap) is stored as a bit mask. If the
duke@435	32	// bit_mask can fit into two words it is stored in
duke@435	33	// the _bit_mask array, otherwise it is allocated on the heap.
duke@435	34	// For OopMapCacheEntry the bit_mask is allocated in the C heap
duke@435	35	// because these entries persist between garbage collections.
duke@435	36	// For InterpreterOopMap the bit_mask is allocated in
duke@435	37	// a resource area for better performance. InterpreterOopMap
duke@435	38	// should only be created and deleted during same garbage collection.
duke@435	39	//
duke@435	40	// If ENABBLE_ZAP_DEAD_LOCALS is defined, two bits are used
duke@435	41	// per entry instead of one. In all cases,
duke@435	42	// the first bit is set to indicate oops as opposed to other
duke@435	43	// values. If the second bit is available,
duke@435	44	// it is set for dead values. We get the following encoding:
duke@435	45	//
duke@435	46	// 00 live value
duke@435	47	// 01 live oop
duke@435	48	// 10 dead value
duke@435	49	// 11 <unused> (we cannot distinguish between dead oops or values with the current oop map generator)
duke@435	50
duke@435	51
duke@435	52	class OffsetClosure {
duke@435	53	public:
duke@435	54	virtual void offset_do(int offset) = 0;
duke@435	55	};
duke@435	56
duke@435	57
duke@435	58	class InterpreterOopMap: ResourceObj {
duke@435	59	friend class OopMapCache;
duke@435	60
duke@435	61	public:
duke@435	62	enum {
duke@435	63	N = 2, // the number of words reserved
duke@435	64	// for inlined mask storage
duke@435	65	small_mask_limit = N * BitsPerWord, // the maximum number of bits
duke@435	66	// available for small masks,
duke@435	67	// small_mask_limit can be set to 0
duke@435	68	// for testing bit_mask allocation
duke@435	69
duke@435	70	#ifdef ENABLE_ZAP_DEAD_LOCALS
duke@435	71	bits_per_entry = 2,
duke@435	72	dead_bit_number = 1,
duke@435	73	#else
duke@435	74	bits_per_entry = 1,
duke@435	75	#endif
duke@435	76	oop_bit_number = 0
duke@435	77	};
duke@435	78
duke@435	79	private:
duke@435	80	methodOop _method; // the method for which the mask is valid
duke@435	81	unsigned short _bci; // the bci for which the mask is valid
duke@435	82	int _mask_size; // the mask size in bits
duke@435	83	int _expression_stack_size; // the size of the expression stack in slots
duke@435	84
duke@435	85	protected:
duke@435	86	intptr_t _bit_mask[N]; // the bit mask if
duke@435	87	// mask_size <= small_mask_limit,
duke@435	88	// ptr to bit mask otherwise
duke@435	89	// "protected" so that sub classes can
duke@435	90	// access it without using trickery in
duke@435	91	// methd bit_mask().
duke@435	92	#ifdef ASSERT
duke@435	93	bool _resource_allocate_bit_mask;
duke@435	94	#endif
duke@435	95
duke@435	96	// access methods
duke@435	97	methodOop method() const { return _method; }
duke@435	98	void set_method(methodOop v) { _method = v; }
duke@435	99	int bci() const { return _bci; }
duke@435	100	void set_bci(int v) { _bci = v; }
duke@435	101	int mask_size() const { return _mask_size; }
duke@435	102	void set_mask_size(int v) { _mask_size = v; }
duke@435	103	int number_of_entries() const { return mask_size() / bits_per_entry; }
duke@435	104	// Test bit mask size and return either the in-line bit mask or allocated
duke@435	105	// bit mask.
duke@435	106	uintptr_t* bit_mask() { return (uintptr_t*)(mask_size() <= small_mask_limit ? (intptr_t)_bit_mask : _bit_mask[0]); }
duke@435	107
duke@435	108	// return the word size of_bit_mask. mask_size() <= 4 * MAX_USHORT
duke@435	109	size_t mask_word_size() {
duke@435	110	return (mask_size() + BitsPerWord - 1) / BitsPerWord;
duke@435	111	}
duke@435	112
duke@435	113	uintptr_t entry_at(int offset) { int i = offset * bits_per_entry; return bit_mask()[i / BitsPerWord] >> (i % BitsPerWord); }
duke@435	114
duke@435	115	void set_expression_stack_size(int sz) { _expression_stack_size = sz; }
duke@435	116
duke@435	117	#ifdef ENABLE_ZAP_DEAD_LOCALS
duke@435	118	bool is_dead(int offset) { return (entry_at(offset) & (1 << dead_bit_number)) != 0; }
duke@435	119	#endif
duke@435	120
duke@435	121	// Lookup
duke@435	122	bool match(methodHandle method, int bci) { return _method == method() && _bci == bci; }
duke@435	123	bool is_empty();
duke@435	124
duke@435	125	// Initialization
duke@435	126	void initialize();
duke@435	127
duke@435	128	public:
duke@435	129	InterpreterOopMap();
duke@435	130	~InterpreterOopMap();
duke@435	131
duke@435	132	// Copy the OopMapCacheEntry in parameter "from" into this
duke@435	133	// InterpreterOopMap. If the _bit_mask[0] in "from" points to
duke@435	134	// allocated space (i.e., the bit mask was to large to hold
duke@435	135	// in-line), allocate the space from a Resource area.
duke@435	136	void resource_copy(OopMapCacheEntry* from);
duke@435	137
duke@435	138	void iterate_oop(OffsetClosure* oop_closure);
duke@435	139	void oop_iterate(OopClosure * blk);
duke@435	140	void oop_iterate(OopClosure * blk, MemRegion mr);
duke@435	141	void verify();
duke@435	142	void print();
duke@435	143
duke@435	144	bool is_oop (int offset) { return (entry_at(offset) & (1 << oop_bit_number )) != 0; }
duke@435	145
duke@435	146	int expression_stack_size() { return _expression_stack_size; }
duke@435	147
duke@435	148	#ifdef ENABLE_ZAP_DEAD_LOCALS
duke@435	149	void iterate_all(OffsetClosure* oop_closure, OffsetClosure* value_closure, OffsetClosure* dead_closure);
duke@435	150	#endif
duke@435	151	};
duke@435	152
duke@435	153	class OopMapCache : public CHeapObj {
duke@435	154	private:
duke@435	155	enum { _size = 32, // Use fixed size for now
duke@435	156	_probe_depth = 3 // probe depth in case of collisions
duke@435	157	};
duke@435	158
duke@435	159	OopMapCacheEntry* _array;
duke@435	160
duke@435	161	unsigned int hash_value_for(methodHandle method, int bci);
duke@435	162	OopMapCacheEntry* entry_at(int i) const;
duke@435	163
duke@435	164	Mutex _mut;
duke@435	165
duke@435	166	void flush();
duke@435	167
duke@435	168	public:
duke@435	169	OopMapCache();
duke@435	170	~OopMapCache(); // free up memory
duke@435	171
duke@435	172	// flush cache entry is occupied by an obsolete method
duke@435	173	void flush_obsolete_entries();
duke@435	174
duke@435	175	// Returns the oopMap for (method, bci) in parameter "entry".
duke@435	176	// Returns false if an oop map was not found.
duke@435	177	void lookup(methodHandle method, int bci, InterpreterOopMap* entry);
duke@435	178
duke@435	179	// Compute an oop map without updating the cache or grabbing any locks (for debugging)
duke@435	180	static void compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry);
duke@435	181
duke@435	182	// Helpers
duke@435	183	// Iterate over the entries in the cached OopMapCacheEntry's
duke@435	184	void oop_iterate(OopClosure *blk);
duke@435	185	void oop_iterate(OopClosure *blk, MemRegion mr);
duke@435	186	void verify();
duke@435	187
duke@435	188	// Returns total no. of bytes allocated as part of OopMapCache's
duke@435	189	static long memory_usage() PRODUCT_RETURN0;
duke@435	190	};