reclaim.c

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    register word *p, *plim;
    register word mark_word;
    register int i;
    NWORDS_DECL
#   define DO_OBJ(start_displ) \
	if (!(mark_word & ((word)1 << start_displ))) { \
	    p[start_displ] = (word)list; \
	    list = (ptr_t)(p+start_displ); \
	    INCR_WORDS(2); \
	}
    
    p = (word *)(hbp->hb_body);
    plim = (word *)(((word)hbp) + HBLKSIZE);

    /* go through all words in block */
	while( p < plim )  {
	    mark_word = *mark_word_addr++;
	    for (i = 0; i < WORDSZ; i += 8) {
		DO_OBJ(0);
		DO_OBJ(2);
		DO_OBJ(4);
		DO_OBJ(6);
		p += 8;
		mark_word >>= 8;
	    }
	}	        
    COUNT_UPDATE
    return(list);
#   undef DO_OBJ
}

/*
 * Another special case for 4 word atomic objects:
 */
/*ARGSUSED*/
ptr_t GC_reclaim_uninit4(hbp, hhdr, list COUNT_PARAM)
register struct hblk *hbp;	/* ptr to current heap block		*/
hdr * hhdr;
register ptr_t list;
COUNT_DECL
{
    register word * mark_word_addr = &(hhdr->hb_marks[0]);
    register word *p, *plim;
    register word mark_word;
    NWORDS_DECL
#   define DO_OBJ(start_displ) \
	if (!(mark_word & ((word)1 << start_displ))) { \
	    p[start_displ] = (word)list; \
	    list = (ptr_t)(p+start_displ); \
	    INCR_WORDS(4); \
	}
    
    p = (word *)(hbp->hb_body);
    plim = (word *)(((word)hbp) + HBLKSIZE);

    /* go through all words in block */
	while( p < plim )  {
	    mark_word = *mark_word_addr++;
	    DO_OBJ(0);
	    DO_OBJ(4);
	    DO_OBJ(8);
	    DO_OBJ(12);
	    DO_OBJ(16);
	    DO_OBJ(20);
	    DO_OBJ(24);
	    DO_OBJ(28);
#	    if CPP_WORDSZ == 64
	      DO_OBJ(32);
	      DO_OBJ(36);
	      DO_OBJ(40);
	      DO_OBJ(44);
	      DO_OBJ(48);
	      DO_OBJ(52);
	      DO_OBJ(56);
	      DO_OBJ(60);
#	    endif
	    p += WORDSZ;
	}	        
    COUNT_UPDATE
    return(list);
#   undef DO_OBJ
}

/* Finally the one word case, which never requires any clearing: */
/*ARGSUSED*/
ptr_t GC_reclaim1(hbp, hhdr, list COUNT_PARAM)
register struct hblk *hbp;	/* ptr to current heap block		*/
hdr * hhdr;
register ptr_t list;
COUNT_DECL
{
    register word * mark_word_addr = &(hhdr->hb_marks[0]);
    register word *p, *plim;
    register word mark_word;
    register int i;
    NWORDS_DECL
#   define DO_OBJ(start_displ) \
	if (!(mark_word & ((word)1 << start_displ))) { \
	    p[start_displ] = (word)list; \
	    list = (ptr_t)(p+start_displ); \
	    INCR_WORDS(1); \
	}
    
    p = (word *)(hbp->hb_body);
    plim = (word *)(((word)hbp) + HBLKSIZE);

    /* go through all words in block */
	while( p < plim )  {
	    mark_word = *mark_word_addr++;
	    for (i = 0; i < WORDSZ; i += 4) {
		DO_OBJ(0);
		DO_OBJ(1);
		DO_OBJ(2);
		DO_OBJ(3);
		p += 4;
		mark_word >>= 4;
	    }
	}	        
    COUNT_UPDATE
    return(list);
#   undef DO_OBJ
}

#endif /* !SMALL_CONFIG && !USE_MARK_BYTES */

/*
 * Generic procedure to rebuild a free list in hbp.
 * Also called directly from GC_malloc_many.
 */
ptr_t GC_reclaim_generic(hbp, hhdr, sz, init, list COUNT_PARAM)
struct hblk *hbp;	/* ptr to current heap block		*/
hdr * hhdr;
GC_bool init;
ptr_t list;
word sz;
COUNT_DECL
{
    ptr_t result = list;

    GC_ASSERT(GC_find_header((ptr_t)hbp) == hhdr);
    GC_remove_protection(hbp, 1, (hhdr)->hb_descr == 0 /* Pointer-free? */);
    if (init) {
      switch(sz) {
#      if !defined(SMALL_CONFIG) && !defined(USE_MARK_BYTES)
        case 1:
	    /* We now issue the hint even if GC_nearly_full returned	*/
	    /* DONT_KNOW.						*/
            result = GC_reclaim1(hbp, hhdr, list COUNT_ARG);
            break;
        case 2:
            result = GC_reclaim_clear2(hbp, hhdr, list COUNT_ARG);
            break;
        case 4:
            result = GC_reclaim_clear4(hbp, hhdr, list COUNT_ARG);
            break;
#      endif /* !SMALL_CONFIG && !USE_MARK_BYTES */
        default:
            result = GC_reclaim_clear(hbp, hhdr, sz, list COUNT_ARG);
            break;
      }
    } else {
      GC_ASSERT((hhdr)->hb_descr == 0 /* Pointer-free block */);
      switch(sz) {
#      if !defined(SMALL_CONFIG) && !defined(USE_MARK_BYTES)
        case 1:
            result = GC_reclaim1(hbp, hhdr, list COUNT_ARG);
            break;
        case 2:
            result = GC_reclaim_uninit2(hbp, hhdr, list COUNT_ARG);
            break;
        case 4:
            result = GC_reclaim_uninit4(hbp, hhdr, list COUNT_ARG);
            break;
#      endif /* !SMALL_CONFIG && !USE_MARK_BYTES */
        default:
            result = GC_reclaim_uninit(hbp, hhdr, sz, list COUNT_ARG);
            break;
      }
    } 
    if (IS_UNCOLLECTABLE(hhdr -> hb_obj_kind)) GC_set_hdr_marks(hhdr);
    return result;
}

/*
 * Restore unmarked small objects in the block pointed to by hbp
 * to the appropriate object free list.
 * If entirely empty blocks are to be completely deallocated, then
 * caller should perform that check.
 */
void GC_reclaim_small_nonempty_block(hbp, report_if_found COUNT_PARAM)
register struct hblk *hbp;	/* ptr to current heap block		*/
int report_if_found;		/* Abort if a reclaimable object is found */
COUNT_DECL
{
    hdr *hhdr = HDR(hbp);
    word sz = hhdr -> hb_sz;
    int kind = hhdr -> hb_obj_kind;
    struct obj_kind * ok = &GC_obj_kinds[kind];
    ptr_t * flh = &(ok -> ok_freelist[sz]);
    
    hhdr -> hb_last_reclaimed = (unsigned short) GC_gc_no;

    if (report_if_found) {
	GC_reclaim_check(hbp, hhdr, sz);
    } else {
        *flh = GC_reclaim_generic(hbp, hhdr, sz,
				  (ok -> ok_init || GC_debugging_started),
	 			  *flh MEM_FOUND_ADDR);
    }
}

/*
 * Restore an unmarked large object or an entirely empty blocks of small objects
 * to the heap block free list.
 * Otherwise enqueue the block for later processing
 * by GC_reclaim_small_nonempty_block.
 * If report_if_found is TRUE, then process any block immediately, and
 * simply report free objects; do not actually reclaim them.
 */
# if defined(__STDC__) || defined(__cplusplus)
    void GC_reclaim_block(register struct hblk *hbp, word report_if_found)
# else
    void GC_reclaim_block(hbp, report_if_found)
    register struct hblk *hbp;	/* ptr to current heap block		*/
    word report_if_found;	/* Abort if a reclaimable object is found */
# endif
{
    register hdr * hhdr;
    register word sz;		/* size of objects in current block	*/
    register struct obj_kind * ok;
    struct hblk ** rlh;

    hhdr = HDR(hbp);
    sz = hhdr -> hb_sz;
    ok = &GC_obj_kinds[hhdr -> hb_obj_kind];

    if( sz > MAXOBJSZ ) {  /* 1 big object */
        if( !mark_bit_from_hdr(hhdr, 0) ) {
	    if (report_if_found) {
	      FOUND_FREE(hbp, 0);
	    } else {
	      word blocks = OBJ_SZ_TO_BLOCKS(sz);
	      if (blocks > 1) {
	        GC_large_allocd_bytes -= blocks * HBLKSIZE;
	      }
#	      ifdef GATHERSTATS
	        GC_mem_found += sz;
#	      endif
	      GC_freehblk(hbp);
	    }
	}
    } else {
        GC_bool empty = GC_block_empty(hhdr);
        if (report_if_found) {
    	  GC_reclaim_small_nonempty_block(hbp, (int)report_if_found
					  MEM_FOUND_ADDR);
        } else if (empty) {
#	  ifdef GATHERSTATS
            GC_mem_found += BYTES_TO_WORDS(HBLKSIZE);
#	  endif
          GC_freehblk(hbp);
        } else if (TRUE != GC_block_nearly_full(hhdr)){
          /* group of smaller objects, enqueue the real work */
          rlh = &(ok -> ok_reclaim_list[sz]);
          hhdr -> hb_next = *rlh;
          *rlh = hbp;
        } /* else not worth salvaging. */
	/* We used to do the nearly_full check later, but we 	*/
	/* already have the right cache context here.  Also	*/
	/* doing it here avoids some silly lock contention in	*/
	/* GC_malloc_many.					*/
    }
}

#if !defined(NO_DEBUGGING)
/* Routines to gather and print heap block info 	*/
/* intended for debugging.  Otherwise should be called	*/
/* with lock.						*/

struct Print_stats
{
	size_t number_of_blocks;
	size_t total_bytes;
};

#ifdef USE_MARK_BYTES

/* Return the number of set mark bits in the given header	*/
int GC_n_set_marks(hhdr)
hdr * hhdr;
{
    register int result = 0;
    register int i;
    
    for (i = 0; i < MARK_BITS_SZ; i++) {
        result += hhdr -> hb_marks[i];
    }
    return(result);
}

#else

/* Number of set bits in a word.  Not performance critical.	*/
static int set_bits(n)
word n;
{
    register word m = n;
    register int result = 0;
    
    while (m > 0) {
    	if (m & 1) result++;
    	m >>= 1;
    }
    return(result);
}

/* Return the number of set mark bits in the given header	*/
int GC_n_set_marks(hhdr)
hdr * hhdr;
{
    register int result = 0;
    register int i;
    
    for (i = 0; i < MARK_BITS_SZ; i++) {
        result += set_bits(hhdr -> hb_marks[i]);
    }
    return(result);
}

#endif /* !USE_MARK_BYTES  */

/*ARGSUSED*/
# if defined(__STDC__) || defined(__cplusplus)
    void GC_print_block_descr(struct hblk *h, word dummy)
# else
    void GC_print_block_descr(h, dummy)
    struct hblk *h;
    word dummy;
# endif
{
    register hdr * hhdr = HDR(h);
    register size_t bytes = WORDS_TO_BYTES(hhdr -> hb_sz);
    struct Print_stats *ps;
    
    GC_printf3("(%lu:%lu,%lu)", (unsigned long)(hhdr -> hb_obj_kind),
    			        (unsigned long)bytes,
    			        (unsigned long)(GC_n_set_marks(hhdr)));
    bytes += HBLKSIZE-1;
    bytes &= ~(HBLKSIZE-1);

    ps = (struct Print_stats *)dummy;
    ps->total_bytes += bytes;
    ps->number_of_blocks++;
}

void GC_print_block_list()
{
    struct Print_stats pstats;

    GC_printf1("(kind(0=ptrfree,1=normal,2=unc.,%lu=stubborn):size_in_bytes, #_marks_set)\n", STUBBORN);
    pstats.number_of_blocks = 0;
    pstats.total_bytes = 0;
    GC_apply_to_all_blocks(GC_print_block_descr, (word)&pstats);
    GC_printf2("\nblocks = %lu, bytes = %lu\n",
    	       (unsigned long)pstats.number_of_blocks,
    	       (unsigned long)pstats.total_bytes);
}

#endif /* NO_DEBUGGING */

/*
 * Clear all obj_link pointers in the list of free objects *flp.
 * Clear *flp.
 * This must be done before dropping a list of free gcj-style objects,
 * since may otherwise end up with dangling "descriptor" pointers.
 * It may help for other pointer-containing objects.
 */
void GC_clear_fl_links(flp)
ptr_t *flp;
{
    ptr_t next = *flp;

    while (0 != next) {
       *flp = 0;
       flp = &(obj_link(next));
       next = *flp;
    }
}

/*
 * Perform GC_reclaim_block on the entire heap, after first clearing
 * small object free lists (if we are not just looking for leaks).
 */
void GC_start_reclaim(report_if_found)
int report_if_found;		/* Abort if a GC_reclaimable object is found */
{
    int kind;
    
#   if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
      GC_ASSERT(0 == GC_fl_builder_count);
#   endif
    /* Clear reclaim- and free-lists */
      for (kind = 0; kind < GC_n_kinds; kind++) {
        ptr_t *fop;
        ptr_t *lim;
        struct hblk ** rlp;
        struct hblk ** rlim;
        struct hblk ** rlist = GC_obj_kinds[kind].ok_reclaim_list;
	GC_bool should_clobber = (GC_obj_kinds[kind].ok_descriptor != 0);
        
        if (rlist == 0) continue;	/* This kind not used.	*/
        if (!report_if_found) {
            lim = &(GC_obj_kinds[kind].ok_freelist[MAXOBJSZ+1]);
	    for( fop = GC_obj_kinds[kind].ok_freelist; fop < lim; fop++ ) {
	      if (*fop != 0) {
		if (should_clobber) {
		  GC_clear_fl_links(fop);
		} else {
	          *fop = 0;
		}
	      }
	    }
	} /* otherwise free list objects are marked, 	*/
	  /* and its safe to leave them			*/
	rlim = rlist + MAXOBJSZ+1;
	for( rlp = rlist; rlp < rlim; rlp++ ) {
	    *rlp = 0;
	}
      }
    
#   ifdef PRINTBLOCKS
        GC_printf0("GC_reclaim: current block sizes:\n");
        GC_print_block_list();
#   endif

  /* Go through all heap blocks (in hblklist) and reclaim unmarked objects */
  /* or enqueue the block for later processing.				   */
    GC_apply_to_all_blocks(GC_reclaim_block, (word)report_if_found);

# ifdef EAGER_SWEEP
    /* This is a very stupid thing to do.  We make it possible anyway,	*/
    /* so that you can convince yourself that it really is very stupid.	*/
    GC_reclaim_all((GC_stop_func)0, FALSE);
# endif
# if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
    GC_ASSERT(0 == GC_fl_builder_count);
# endif
    
}

/*
 * Sweep blocks of the indicated object size and kind until either the
 * appropriate free list is nonempty, or there are no more blocks to
 * sweep.
 */
void GC_continue_reclaim(sz, kind)
word sz;	/* words */
int kind;
{
    register hdr * hhdr;
    register struct hblk * hbp;
    register struct obj_kind * ok = &(GC_obj_kinds[kind]);
    struct hblk ** rlh = ok -> ok_reclaim_list;
    ptr_t *flh = &(ok -> ok_freelist[sz]);
    
    if (rlh == 0) return;	/* No blocks of this kind.	*/
    rlh += sz;
    while ((hbp = *rlh) != 0) {
        hhdr = HDR(hbp);
        *rlh = hhdr -> hb_next;
        GC_reclaim_small_nonempty_block(hbp, FALSE MEM_FOUND_ADDR);
        if (*flh != 0) break;
    }
}

/*
 * Reclaim all small blocks waiting to be reclaimed.
 * Abort and return FALSE when/if (*stop_func)() returns TRUE.
 * If this returns TRUE, then it's safe to restart the world
 * with incorrectly cleared mark bits.
 * If ignore_old is TRUE, then reclaim only blocks that have been 
 * recently reclaimed, and discard the rest.
 * Stop_func may be 0.
 */
GC_bool GC_reclaim_all(stop_func, ignore_old)
GC_stop_func stop_func;
GC_bool ignore_old;
{
    register word sz;
    register int kind;
    register hdr * hhdr;
    register struct hblk * hbp;
    register struct obj_kind * ok;
    struct hblk ** rlp;
    struct hblk ** rlh;
#   ifdef PRINTTIMES
	CLOCK_TYPE start_time;
	CLOCK_TYPE done_time;
	
	GET_TIME(start_time);
#   endif
    
    for (kind = 0; kind < GC_n_kinds; kind++) {
    	ok = &(GC_obj_kinds[kind]);
    	rlp = ok -> ok_reclaim_list;
    	if (rlp == 0) continue;
    	for (sz = 1; sz <= MAXOBJSZ; sz++) {
    	    rlh = rlp + sz;
    	    while ((hbp = *rlh) != 0) {
    	        if (stop_func != (GC_stop_func)0 && (*stop_func)()) {
    	            return(FALSE);
    	        }
        	hhdr = HDR(hbp);
        	*rlh = hhdr -> hb_next;
        	if (!ignore_old || hhdr -> hb_last_reclaimed == GC_gc_no - 1) {
        	    /* It's likely we'll need it this time, too	*/
        	    /* It's been touched recently, so this	*/
        	    /* shouldn't trigger paging.		*/
        	    GC_reclaim_small_nonempty_block(hbp, FALSE MEM_FOUND_ADDR);
        	}
            }
        }
    }
#   ifdef PRINTTIMES
	GET_TIME(done_time);
	GC_printf1("Disposing of reclaim lists took %lu msecs\n",
	           MS_TIME_DIFF(done_time,start_time));
#   endif
    return(TRUE);
}