path: root/gs/src/gxalloc.h

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 */


/* Requires gsmemory.h, gsstruct.h */

#ifndef gxalloc_INCLUDED
#  define gxalloc_INCLUDED

#ifndef gs_ref_memory_DEFINED
#  define gs_ref_memory_DEFINED
typedef struct gs_ref_memory_s gs_ref_memory_t;

#endif

#include "gsalloc.h"
#include "gxobj.h"

/* ================ Chunks ================ */

/*
 * We obtain memory from the operating system in `chunks'.  A chunk
 * may hold only a single large object (or string), or it may hold
 * many objects (allocated from the bottom up, always aligned)
 * and strings (allocated from the top down, not aligned).
 */

/*
 * Refs are allocated in the bottom-up section, along with struct objects.
 * In order to keep the overhead for refs small, we make consecutive
 * blocks of refs into a single allocator object of type st_refs.
 * To do this, we remember the start of the current ref object (if any),
 * and the end of the last block of allocated refs.  As long as
 * the latter is equal to the top of the allocated area, we can add
 * more refs to the current object; otherwise, we have to start a new one.
 * We assume that sizeof(ref) % obj_align_mod == 0; this means that if we
 * ever have to pad a block of refs, we never add as much as one entire ref.
 */

/*
 * When we do a save, we create a new 'inner' chunk out of the remaining
 * space in the currently active chunk.  Inner chunks must not be freed
 * by a restore.
 *
 * The garbage collector implements relocation for refs by scanning
 * forward to a free object.  Because of this, every ref object must end
 * with a dummy ref that can hold the relocation for the last block.
 * In order to put a reasonable upper bound on the scanning time, we
 * limit the length of the objects that contain runs of refs.
 */
#define max_size_st_refs (50 * sizeof(ref))

/*
 * Strings carry some additional overhead for use by the GC.
 * At the top of the chunk is a table of relocation values for
 * 16N-character blocks of strings, where N is sizeof(uint).
 * This table is aligned, by adding padding above it if necessary.
 * Just below it is a mark table for the strings.  This table is also aligned,
 * to improve GC performance. The actual string data start below
 * the mark table.  These tables are not needed for a chunk that holds
 * a single large (non-string) object, but they are needed for all other
 * chunks, including chunks created to hold a single large string.
 */

/*
 * Define the unit of data manipulation for marking strings.
 */
typedef uint string_mark_unit;

#define log2_sizeof_string_mark_unit arch_log2_sizeof_int
/*
 * Define the quantum of relocation for strings, which determines
 * the quantum for reserving space.  This value must be a power of 2,
 * must be at least sizeof(string_mark_unit) * 8, and (because of the
 * unrolled loops in igcstr.c) currently must be equal to either 32 or 64.
 */
typedef uint string_reloc_offset;

#define log2_string_data_quantum (arch_log2_sizeof_int + 4)
#define string_data_quantum (1 << log2_string_data_quantum)
/*
 * Define the quantum for reserving string space, including data,
 * marks, and relocation.
 */
#define string_space_quantum\
  (string_data_quantum + (string_data_quantum / 8) +\
   sizeof(string_reloc_offset))
/*
 * Compute the amount of space needed for a chunk that holds only
 * a string of a given size.
 */
#define string_chunk_space(nbytes)\
  (((nbytes) + (string_data_quantum - 1)) / string_data_quantum *\
   string_space_quantum)
/*
 * Compute the number of string space quanta in a given amount of storage.
 */
#define string_space_quanta(spacebytes)\
  ((spacebytes) / string_space_quantum)
/*
 * Compute the size of string marks for a given number of quanta.
 */
#define string_quanta_mark_size(nquanta)\
  ((nquanta) * (string_data_quantum / 8))
/*
 * Compute the size of the string freelists for a chunk.
 */
#define STRING_FREELIST_SPACE(cp)\
  (((cp->climit - csbase(cp) + 255) >> 8) * sizeof(*cp->sfree1))

/*
 * To allow the garbage collector to combine chunks, we store in the
 * head of each chunk the address to which its contents will be moved.
 */
/*typedef struct chunk_head_s chunk_head_t; *//* in gxobj.h */

/* Structure for a chunk. */
typedef struct chunk_s chunk_t;
struct chunk_s {
    chunk_head_t *chead;	/* chunk head, bottom of chunk; */
    /* csbase is an alias for chead */
#define csbase(cp) ((byte *)(cp)->chead)
    /* Note that allocation takes place both from the bottom up */
    /* (aligned objects) and from the top down (strings). */
    byte *cbase;		/* bottom of chunk data area */
    byte *int_freed_top;	/* top of most recent internal free area */
				/* in chunk (which may no longer be free), */
				/* used to decide when to consolidate */
				/* trailing free space in allocated area */
    byte *cbot;			/* bottom of free area */
				/* (top of aligned objects) */
    obj_header_t *rcur;		/* current refs object, 0 if none */
    byte *rtop;			/* top of rcur */
    byte *ctop;			/* top of free area */
				/* (bottom of strings) */
    byte *climit;		/* top of strings */
    byte *cend;			/* top of chunk */
    chunk_t *cprev;		/* chain chunks together, */
    chunk_t *cnext;		/*   sorted by address */
    chunk_t *outer;		/* the chunk of which this is */
				/*   an inner chunk, if any */
    uint inner_count;		/* number of chunks of which this is */
				/*   the outer chunk, if any */
    bool has_refs;		/* true if any refs in chunk */
    /*
     * Free lists for single bytes in blocks of 1 to 2*N-1 bytes, one per
     * 256 bytes in [csbase..climit), where N is sizeof(uint). The chain
     * pointer is a (1-byte) self-relative offset, terminated by a 0;
     * obviously, the chain is sorted by increasing address.  The free list
     * pointers themselves are offsets relative to csbase.
     *
     * Note that these lists overlay the GC relocation table, and that
     * sizeof(*sfree1) / 256 must be less than sizeof(string_reloc_offset) /
     * string_data_quantum (as real numbers).
     */
#define SFREE_NB 4		/* # of bytes for values on sfree list */
    uint *sfree1;
    /*
     * Free list for blocks of >= 2*N bytes.  Each block begins
     * with a N-byte size and a N-byte next block pointer,
     * both big-endian.  This too is sorted in increasing address order.
     */
    uint sfree;
    /* The remaining members are for the GC. */
    byte *odest;		/* destination for objects */
    byte *smark;		/* mark bits for strings */
    uint smark_size;
    byte *sbase;		/* base for computing smark offsets */
    string_reloc_offset *sreloc;	/* relocation for string blocks */
    byte *sdest;		/* destination for (top of) strings */
    byte *rescan_bot;		/* bottom of rescanning range if */
				/* the GC mark stack overflows */
    byte *rescan_top;		/* top of range ditto */
};

/* The chunk descriptor is exported only for isave.c. */
extern_st(st_chunk);
#define public_st_chunk()	/* in ialloc.c */\
  gs_public_st_ptrs2(st_chunk, chunk_t, "chunk_t",\
    chunk_enum_ptrs, chunk_reloc_ptrs, cprev, cnext)

/*
 * Macros for scanning a chunk linearly, with the following schema:
 *      SCAN_CHUNK_OBJECTS(cp)                  << declares pre, size >>
 *              << code for all objects -- size not set yet >>
 *      DO_LARGE
 *              << code for large objects >>
 *      DO_SMALL
 *              << code for small objects >>
 *      END_OBJECTS_SCAN
 * If large and small objects are treated alike, one can use DO_ALL instead
 * of DO_LARGE and DO_SMALL.
 */
#define SCAN_CHUNK_OBJECTS(cp)\
	{	obj_header_t *pre = (obj_header_t *)((cp)->cbase);\
		obj_header_t *end = (obj_header_t *)((cp)->cbot);\
		ulong size;		/* long because of large objects */\
		for ( ; pre < end;\
			pre = (obj_header_t *)((char *)pre + obj_size_round(size))\
		    )\
		{
#define DO_LARGE\
			if ( pre->o_large )\
			{	size = pre_obj_large_size(pre);\
				{
#define DO_SMALL\
				}\
			} else\
			{	size = pre_obj_small_size(pre);\
				{
#define DO_ALL\
			{	size = pre_obj_contents_size(pre);\
				{
#define END_OBJECTS_SCAN_INCOMPLETE\
				}\
			}\
		}\
	}
#ifdef DEBUG
#  define END_OBJECTS_SCAN\
				}\
			}\
		}\
		if ( pre != end )\
		{	lprintf2("Chunk parsing error, 0x%lx != 0x%lx\n",\
				 (ulong)pre, (ulong)end);\
			gs_exit(1);\
		}\
	}
#else
#  define END_OBJECTS_SCAN END_OBJECTS_SCAN_INCOMPLETE
#endif

/* Initialize a chunk. */
/* This is exported for save/restore. */
void alloc_init_chunk(P5(chunk_t *, byte *, byte *, bool, chunk_t *));

/* Initialize the string freelists in a chunk. */
void alloc_init_free_strings(P1(chunk_t *));

/* Find the chunk for a pointer. */
/* Note that ptr_is_within_chunk returns true even if the pointer */
/* is in an inner chunk of the chunk being tested. */
#define ptr_is_within_chunk(ptr, cp)\
  PTR_BETWEEN((const byte *)(ptr), (cp)->cbase, (cp)->cend)
#define ptr_is_in_inner_chunk(ptr, cp)\
  ((cp)->inner_count != 0 &&\
   PTR_BETWEEN((const byte *)(ptr), (cp)->cbot, (cp)->ctop))
#define ptr_is_in_chunk(ptr, cp)\
  (ptr_is_within_chunk(ptr, cp) && !ptr_is_in_inner_chunk(ptr, cp))
typedef struct chunk_locator_s {
    const gs_ref_memory_t *memory;	/* for head & tail of chain */
    chunk_t *cp;		/* one-element cache */
} chunk_locator_t;
bool chunk_locate_ptr(P2(const void *, chunk_locator_t *));

#define chunk_locate(ptr, clp)\
  (((clp)->cp != 0 && ptr_is_in_chunk(ptr, (clp)->cp)) ||\
   chunk_locate_ptr(ptr, clp))

/* Close up the current chunk. */
/* This is exported for save/restore and for the GC. */
void alloc_close_chunk(P1(gs_ref_memory_t * mem));

/* Reopen the current chunk after a GC. */
void alloc_open_chunk(P1(gs_ref_memory_t * mem));

/* Insert or remove a chunk in the address-ordered chain. */
/* These are exported for the GC. */
void alloc_link_chunk(P2(chunk_t *, gs_ref_memory_t *));
void alloc_unlink_chunk(P2(chunk_t *, gs_ref_memory_t *));

/* Free a chunk.  This is exported for save/restore and for the GC. */
void alloc_free_chunk(P2(chunk_t *, gs_ref_memory_t *));

/* Print a chunk debugging message. */
/* Unfortunately, the ANSI C preprocessor doesn't allow us to */
/* define the list of variables being printed as a macro. */
#define dprintf_chunk_format\
  "%s 0x%lx (0x%lx..0x%lx, 0x%lx..0x%lx..0x%lx)\n"
#define dprintf_chunk(msg, cp)\
  dprintf7(dprintf_chunk_format,\
	   msg, (ulong)(cp), (ulong)(cp)->cbase, (ulong)(cp)->cbot,\
	   (ulong)(cp)->ctop, (ulong)(cp)->climit, (ulong)(cp)->cend)
#define if_debug_chunk(c, msg, cp)\
  if_debug7(c, dprintf_chunk_format,\
	    msg, (ulong)(cp), (ulong)(cp)->cbase, (ulong)(cp)->cbot,\
	    (ulong)(cp)->ctop, (ulong)(cp)->climit, (ulong)(cp)->cend)

/* ================ Allocator state ================ */

/* Structures for save/restore (not defined here). */
struct alloc_save_s;
struct alloc_change_s;

/* Stream structure, only needed for the streams member of the state. */
#ifndef stream_DEFINED
#  define stream_DEFINED
typedef struct stream_s stream;

#endif

/*
 * Define the number of freelists.  The index in the freelist array
 * is the ceiling of the size of the object contents (i.e., not including
 * the header) divided by obj_align_mod. There is an extra entry used to
 * keep a list of all free blocks > max_freelist_size.
 */
#define max_freelist_size 800	/* big enough for gstate & contents */
#define num_small_freelists\
  ((max_freelist_size + obj_align_mod - 1) / obj_align_mod + 1)
#define num_freelists (num_small_freelists + 1)

/*
 * Define the index of the freelist containing all free blocks >
 * max_freelist_size.
 */
#define LARGE_FREELIST_INDEX	num_small_freelists

/* Define the memory manager subclass for this allocator. */
struct gs_ref_memory_s {
    /* The following are set at initialization time. */
    gs_memory_common;
    gs_raw_memory_t *parent;	/* for allocating chunks */
    uint chunk_size;
    uint large_size;		/* min size to give large object */
				/* its own chunk: must be */
				/* 1 mod obj_align_mod */
    gs_ref_memory_t *global;	/* global VM for this allocator */
				/* (may point to itself) */
    uint space;			/* a_local, a_global, a_system */
    /* Callers can change the following dynamically */
    /* (through a procedural interface). */
    gs_memory_gc_status_t gc_status;
    /* The following are updated dynamically. */
    bool is_controlled;		/* if true, this allocator doesn't manage */
				/* its own chunks */
    ulong limit;		/* signal a VMerror when total */
				/* allocated exceeds this */
    chunk_t *cfirst;		/* head of chunk list */
    chunk_t *clast;		/* tail of chunk list */
    chunk_t cc;			/* current chunk */
    chunk_t *pcc;		/* where to store cc */
    chunk_locator_t cfreed;	/* chunk where last object freed */
    ulong allocated;		/* total size of all chunks */
				/* allocated at this save level */
    long inherited;		/* chunks allocated at outer save */
				/* levels that should be counted */
				/* towards the GC threshold */
				/* (may be negative, but allocated + */
				/* inherited >= 0 always) */
    ulong gc_allocated;		/* value of (allocated + */
				/* previous_status.allocated) after last GC */
    struct lost_ {		/* space freed and 'lost' (not put on a */
				/* freelist) */
	ulong objects;
	ulong refs;
	ulong strings;
    } lost;
    /*
     * The following are for the interpreter's convenience: the
     * library initializes them to 0 and then never touches them.
     */
    stream *streams;
    /* Garbage collector information */
    gs_gc_root_t *roots;	/* roots for GC */
    /* Sharing / saved state information */
    int num_contexts;		/* # of contexts sharing this VM */
    struct alloc_change_s *changes;
    struct alloc_save_s *saved;
    long total_scanned;
    struct alloc_save_s *reloc_saved;	/* for GC */
    gs_memory_status_t previous_status;		/* total allocated & used */
				/* in outer save levels */
    /* We put the freelists last to keep the scalar offsets small. */
    obj_header_t *freelists[num_freelists];
};

/* The descriptor for gs_ref_memory_t is exported only for */
/* the alloc_save_t subclass; otherwise, it should be private. */
extern_st(st_ref_memory);
#define public_st_ref_memory()	/* in gsalloc.c */\
  gs_public_st_composite(st_ref_memory, gs_ref_memory_t,\
    "gs_ref_memory", ref_memory_enum_ptrs, ref_memory_reloc_ptrs)
#define st_ref_memory_max_ptrs 3	/* streams, changes, saved */

/* Define the procedures for the standard allocator. */
/* We export this for subclasses. */
extern const gs_memory_procs_t gs_ref_memory_procs;

/*
 * Scan the chunks of an allocator:
 *      SCAN_MEM_CHUNKS(mem, cp)
 *              << code to process chunk cp >>
 *      END_CHUNKS_SCAN
 */
#define SCAN_MEM_CHUNKS(mem, cp)\
	{	chunk_t *cp = (mem)->cfirst;\
		for ( ; cp != 0; cp = cp->cnext )\
		{
#define END_CHUNKS_SCAN\
		}\
	}

/* ================ Debugging ================ */

#ifdef DEBUG

/*
 * Define the options for a memory dump.  These may be or'ed together.
 */
typedef enum {
    dump_do_default = 0,	/* pro forma */
    dump_do_strings = 1,
    dump_do_type_addresses = 2,
    dump_do_no_types = 4,
    dump_do_pointers = 8,
    dump_do_pointed_strings = 16,	/* only if do_pointers also set */
    dump_do_contents = 32,
    dump_do_marks = 64
} dump_options_t;

/*
 * Define all the parameters controlling what gets dumped.
 */
typedef struct dump_control_s {
    dump_options_t options;
    const byte *bottom;
    const byte *top;
} dump_control_t;

/* Define the two most useful dump control structures. */
extern const dump_control_t dump_control_default;
extern const dump_control_t dump_control_all;

/* ------ Procedures ------ */

/* Print one object with the given options. */
/* Relevant options: type_addresses, no_types, pointers, pointed_strings, */
/* contents. */
void debug_print_object(P2(const void *obj, const dump_control_t * control));

/* Print the contents of a chunk with the given options. */
/* Relevant options: all. */
void debug_dump_chunk(P2(const chunk_t * cp, const dump_control_t * control));
void debug_print_chunk(P1(const chunk_t * cp));	/* default options */

/* Print the contents of all chunks managed by an allocator. */
/* Relevant options: all. */
void debug_dump_memory(P2(const gs_ref_memory_t * mem,
    const dump_control_t * control));

#endif /* DEBUG */

#endif /* gxalloc_INCLUDED */