constpool.h

linux下建立JAVA虚拟机的源码KAFFE

/* constpool.h
 * Manage the constant pool.
 *
 * Copyright (c) 1996, 1997
 *	Transvirtual Technologies, Inc.  All rights reserved.
 *
 * See the file "license.terms" for information on usage and redistribution 
 * of this file. 
 */

#ifndef __jit_constpool_h
#define __jit_constpool_h

/*
 * The per-method constant pool is used to store large constants used by a
 * method that cannot be inlined in the instruction stream.  For example, on a
 * RISC CPU, like the PowerPC, only 16 bit immediates can be stored in the
 * instruction stream.  Therefore, we prepend a block of constants to the
 * generated code so that the method can reference them using pc-relative
 * addressing.
 */


/**
 * Constant pool value types:
 *   CPint - A jint
 *   CPlong - A jlong
 *   CPref - A void *
 *   CPfloat - A float
 *   CPdouble - A double
 *   CPstring - A char * XXX ???
 *   CPlabel - A void * XXX ???
 */
enum {
	CP_min,
	
	CPint,
	CPlong,
	CPref,
	CPfloat,
	CPdouble,
	CPstring,
	CPlabel,
	
	CP_max,
};

/**
 * The constpool structure is a linked list node that is used to track the
 * constants that will be placed in the block.
 *
 * next - Link to the next constpool in the list.
 * at - The location of the constant in the constpool.  This value is not
 *   generated until establishConstants() is called, which is after the
 *   instructions have been generated, but before labels have been linked.
 * type - The type of constant, needs to be one of the above CP* values.
 * val - The constant's value.
 */
typedef struct _constpool {
	struct _constpool* next;
	uintp		   at;
	int		   type;
	union _constpoolval {
		jint	   i;
		jlong	   l;
		void*	   r;
		float	   f;
		double	   d;
	} val;
} constpool;

#define ALLOCCONSTNR	64

/**
 * constpools are allocated and tracked as part of a chunk as represented by
 * this structure.
 *
 * next - Link to the next chunk in the list.
 * data - The constpools contained in the chunk.
 */
typedef struct _constpoolchunk {
	struct _constpoolchunk *next;
	constpool data[ALLOCCONSTNR];
} constpoolchunk;

/**
 * Allocate a new constpool object and link it in to the global list.
 *
 * @param type Type of value to store in the constpool.
 * @param ...  The value to store.
 *
 * Example:
 *   newConstant(CPint, 256);
 */
constpool* KaffeJIT3_newConstant(int type, ...);

/**
 * Copy the list of constant values to the given location and update the "at"
 * values in the constpool objects.
 *
 * @param at The location of the constant pool for the current method.
 */
void KaffeJIT3_establishConstants(void *at);

/**
 * Reset the constant pool global data structures for a new method.
 */
void KaffeJIT3_resetConstants(void);

/**
 * Return the number of constants allocated since the last resetConstants.
 */
uint32 KaffeJIT3_getNumberOfConstants(void);

/**
 * Return the first constpool object.
 */
constpool* KaffeJIT3_getFirstConst(void);

/**
 * Return the current constpool object.
 */
constpool* KaffeJIT3_getCurrConst(void);

#endif