misc.c

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/* 
 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
 * Copyright (c) 1999-2001 by Hewlett-Packard Company. All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 */
/* Boehm, July 31, 1995 5:02 pm PDT */


#include <stdio.h>
#include <limits.h>
#include <stdarg.h>
#ifndef _WIN32_WCE
#include <signal.h>
#endif

#define I_HIDE_POINTERS	/* To make GC_call_with_alloc_lock visible */
#include "private/gc_pmark.h"

#ifdef GC_SOLARIS_THREADS
# include <sys/syscall.h>
#endif
#if defined(MSWIN32) || defined(MSWINCE)
# define WIN32_LEAN_AND_MEAN
# define NOSERVICE
# include <windows.h>
# include <tchar.h>
#endif

#ifdef UNIX_LIKE
# include <fcntl.h>
# include <sys/types.h>
# include <sys/stat.h>

  int GC_log;  /* Forward decl, so we can set it.	*/
#endif

#ifdef NONSTOP
# include <floss.h>
#endif

#if defined(THREADS) && defined(PCR)
# include "il/PCR_IL.h"
  PCR_Th_ML GC_allocate_ml;
#endif
/* For other platforms with threads, the lock and possibly		*/
/* GC_lock_holder variables are defined in the thread support code.	*/

#if defined(NOSYS) || defined(ECOS)
#undef STACKBASE
#endif

/* Dont unnecessarily call GC_register_main_static_data() in case 	*/
/* dyn_load.c isn't linked in.						*/
#ifdef DYNAMIC_LOADING
# define GC_REGISTER_MAIN_STATIC_DATA() GC_register_main_static_data()
#else
# define GC_REGISTER_MAIN_STATIC_DATA() TRUE
#endif

GC_FAR struct _GC_arrays GC_arrays /* = { 0 } */;


GC_bool GC_debugging_started = FALSE;
	/* defined here so we don't have to load debug_malloc.o */

void (*GC_check_heap) (void) = (void (*) (void))0;
void (*GC_print_all_smashed) (void) = (void (*) (void))0;

void (*GC_start_call_back) (void) = (void (*) (void))0;

ptr_t GC_stackbottom = 0;

#ifdef IA64
  ptr_t GC_register_stackbottom = 0;
#endif

GC_bool GC_dont_gc = 0;

GC_bool GC_dont_precollect = 0;

GC_bool GC_quiet = 0;

#ifndef SMALL_CONFIG
  GC_bool GC_print_stats = 0;
#endif

GC_bool GC_print_back_height = 0;

#ifndef NO_DEBUGGING
  GC_bool GC_dump_regularly = 0;  /* Generate regular debugging dumps. */
#endif

#ifdef KEEP_BACK_PTRS
  long GC_backtraces = 0;	/* Number of random backtraces to 	*/
  				/* generate for each GC.		*/
#endif

#ifdef FIND_LEAK
  int GC_find_leak = 1;
#else
  int GC_find_leak = 0;
#endif

#ifdef ALL_INTERIOR_POINTERS
  int GC_all_interior_pointers = 1;
#else
  int GC_all_interior_pointers = 0;
#endif

long GC_large_alloc_warn_interval = 5;
	/* Interval between unsuppressed warnings.	*/

long GC_large_alloc_warn_suppressed = 0;
	/* Number of warnings suppressed so far.	*/

/*ARGSUSED*/
void * GC_default_oom_fn(size_t bytes_requested)
{
    return(0);
}

void * (*GC_oom_fn) (size_t bytes_requested) = GC_default_oom_fn;

void * GC_project2(void *arg1, void *arg2)
{
  return arg2;
}

/* Set things up so that GC_size_map[i] >= granules(i),		*/
/* but not too much bigger						*/
/* and so that size_map contains relatively few distinct entries 	*/
/* This was originally stolen from Russ Atkinson's Cedar		*/
/* quantization alogrithm (but we precompute it).			*/ 
void GC_init_size_map(void)
{
    int i;

    /* Map size 0 to something bigger.			*/
    /* This avoids problems at lower levels.		*/
      GC_size_map[0] = 1;
    for (i = 1; i <= GRANULES_TO_BYTES(TINY_FREELISTS-1) - EXTRA_BYTES; i++) {
        GC_size_map[i] = ROUNDED_UP_GRANULES(i);
        GC_ASSERT(GC_size_map[i] < TINY_FREELISTS);
    }
    /* We leave the rest of the array to be filled in on demand. */
}

/* Fill in additional entries in GC_size_map, including the ith one */
/* We assume the ith entry is currently 0.				*/
/* Note that a filled in section of the array ending at n always    */
/* has length at least n/4.						*/
void GC_extend_size_map(size_t i)
{
    size_t orig_granule_sz = ROUNDED_UP_GRANULES(i);
    size_t granule_sz = orig_granule_sz;
    size_t byte_sz = GRANULES_TO_BYTES(granule_sz);
    			/* The size we try to preserve.		*/
    			/* Close to i, unless this would	*/
    			/* introduce too many distinct sizes.	*/
    size_t smaller_than_i = byte_sz - (byte_sz >> 3);
    size_t much_smaller_than_i = byte_sz - (byte_sz >> 2);
    size_t low_limit;	/* The lowest indexed entry we 	*/
    			/* initialize.			*/
    size_t j;
    
    if (GC_size_map[smaller_than_i] == 0) {
        low_limit = much_smaller_than_i;
        while (GC_size_map[low_limit] != 0) low_limit++;
    } else {
        low_limit = smaller_than_i + 1;
        while (GC_size_map[low_limit] != 0) low_limit++;
        granule_sz = ROUNDED_UP_GRANULES(low_limit);
        granule_sz += granule_sz >> 3;
        if (granule_sz < orig_granule_sz) granule_sz = orig_granule_sz;
    }
    /* For these larger sizes, we use an even number of granules.	*/
    /* This makes it easier to, for example, construct a 16byte-aligned	*/
    /* allocator even if GRANULE_BYTES is 8.				*/
        granule_sz += 1;
        granule_sz &= ~1;
    if (granule_sz > MAXOBJGRANULES) {
        granule_sz = MAXOBJGRANULES;
    }
    /* If we can fit the same number of larger objects in a block,	*/
    /* do so.							*/ 
    {
        size_t number_of_objs = HBLK_GRANULES/granule_sz;
        granule_sz = HBLK_GRANULES/number_of_objs;
    	granule_sz &= ~1;
    }
    byte_sz = GRANULES_TO_BYTES(granule_sz);
    /* We may need one extra byte;			*/
    /* don't always fill in GC_size_map[byte_sz]	*/
    byte_sz -= EXTRA_BYTES;

    for (j = low_limit; j <= byte_sz; j++) GC_size_map[j] = granule_sz;  
}


/*
 * The following is a gross hack to deal with a problem that can occur
 * on machines that are sloppy about stack frame sizes, notably SPARC.
 * Bogus pointers may be written to the stack and not cleared for
 * a LONG time, because they always fall into holes in stack frames
 * that are not written.  We partially address this by clearing
 * sections of the stack whenever we get control.
 */
word GC_stack_last_cleared = 0;	/* GC_no when we last did this */
# ifdef THREADS
#   define BIG_CLEAR_SIZE 2048	/* Clear this much now and then.	*/
#   define SMALL_CLEAR_SIZE 256 /* Clear this much every time.		*/
# endif
# define CLEAR_SIZE 213  /* Granularity for GC_clear_stack_inner */
# define DEGRADE_RATE 50

ptr_t GC_min_sp;	/* Coolest stack pointer value from which we've */
			/* already cleared the stack.			*/
			
ptr_t GC_high_water;
			/* "hottest" stack pointer value we have seen	*/
			/* recently.  Degrades over time.		*/

word GC_bytes_allocd_at_reset;

#if defined(ASM_CLEAR_CODE)
  extern void *GC_clear_stack_inner(void *, ptr_t);
#else  
/* Clear the stack up to about limit.  Return arg. */
/*ARGSUSED*/
void * GC_clear_stack_inner(void *arg, ptr_t limit)
{
    word dummy[CLEAR_SIZE];
    
    BZERO(dummy, CLEAR_SIZE*sizeof(word));
    if ((ptr_t)(dummy) COOLER_THAN limit) {
        (void) GC_clear_stack_inner(arg, limit);
    }
    /* Make sure the recursive call is not a tail call, and the bzero	*/
    /* call is not recognized as dead code.				*/
    GC_noop1((word)dummy);
    return(arg);
}
#endif

/* Clear some of the inaccessible part of the stack.  Returns its	*/
/* argument, so it can be used in a tail call position, hence clearing  */
/* another frame.							*/
void * GC_clear_stack(void *arg)
{
    ptr_t sp = GC_approx_sp();  /* Hotter than actual sp */
#   ifdef THREADS
        word dummy[SMALL_CLEAR_SIZE];
	static unsigned random_no = 0;
       			 	 /* Should be more random than it is ... */
				 /* Used to occasionally clear a bigger	 */
				 /* chunk.				 */
#   endif
    ptr_t limit;
    
#   define SLOP 400
	/* Extra bytes we clear every time.  This clears our own	*/
	/* activation record, and should cause more frequent		*/
	/* clearing near the cold end of the stack, a good thing.	*/
#   define GC_SLOP 4000
	/* We make GC_high_water this much hotter than we really saw   	*/
	/* saw it, to cover for GC noise etc. above our current frame.	*/
#   define CLEAR_THRESHOLD 100000
	/* We restart the clearing process after this many bytes of	*/
	/* allocation.  Otherwise very heavily recursive programs	*/
	/* with sparse stacks may result in heaps that grow almost	*/
	/* without bounds.  As the heap gets larger, collection 	*/
	/* frequency decreases, thus clearing frequency would decrease, */
	/* thus more junk remains accessible, thus the heap gets	*/
	/* larger ...							*/
# ifdef THREADS
    if (++random_no % 13 == 0) {
	limit = sp;
	MAKE_HOTTER(limit, BIG_CLEAR_SIZE*sizeof(word));
	limit = (ptr_t)((word)limit & ~0xf);
        		/* Make it sufficiently aligned for assembly	*/
        		/* implementations of GC_clear_stack_inner.	*/
	return GC_clear_stack_inner(arg, limit);
    } else {
	BZERO(dummy, SMALL_CLEAR_SIZE*sizeof(word));
	return arg;
    }
# else
    if (GC_gc_no > GC_stack_last_cleared) {
        /* Start things over, so we clear the entire stack again */
        if (GC_stack_last_cleared == 0) GC_high_water = (ptr_t)GC_stackbottom;
        GC_min_sp = GC_high_water;
        GC_stack_last_cleared = GC_gc_no;
        GC_bytes_allocd_at_reset = GC_bytes_allocd;
    }
    /* Adjust GC_high_water */
        MAKE_COOLER(GC_high_water, WORDS_TO_BYTES(DEGRADE_RATE) + GC_SLOP);
        if (sp HOTTER_THAN GC_high_water) {
            GC_high_water = sp;
        }
        MAKE_HOTTER(GC_high_water, GC_SLOP);
    limit = GC_min_sp;
    MAKE_HOTTER(limit, SLOP);
    if (sp COOLER_THAN limit) {
        limit = (ptr_t)((word)limit & ~0xf);
			/* Make it sufficiently aligned for assembly	*/
        		/* implementations of GC_clear_stack_inner.	*/
        GC_min_sp = sp;
        return(GC_clear_stack_inner(arg, limit));
    } else if (GC_bytes_allocd - GC_bytes_allocd_at_reset > CLEAR_THRESHOLD) {
    	/* Restart clearing process, but limit how much clearing we do. */
    	GC_min_sp = sp;
    	MAKE_HOTTER(GC_min_sp, CLEAR_THRESHOLD/4);
    	if (GC_min_sp HOTTER_THAN GC_high_water) GC_min_sp = GC_high_water;
    	GC_bytes_allocd_at_reset = GC_bytes_allocd;
    }  
    return(arg);
# endif
}


/* Return a pointer to the base address of p, given a pointer to a	*/
/* an address within an object.  Return 0 o.w.				*/
void * GC_base(void * p)
{
    ptr_t r;
    struct hblk *h;
    bottom_index *bi;
    hdr *candidate_hdr;
    ptr_t limit;
    
    r = p;
    if (!GC_is_initialized) return 0;
    h = HBLKPTR(r);
    GET_BI(r, bi);
    candidate_hdr = HDR_FROM_BI(bi, r);
    if (candidate_hdr == 0) return(0);
    /* If it's a pointer to the middle of a large object, move it	*/
    /* to the beginning.						*/
	while (IS_FORWARDING_ADDR_OR_NIL(candidate_hdr)) {
	   h = FORWARDED_ADDR(h,candidate_hdr);
	   r = (ptr_t)h;
	   candidate_hdr = HDR(h);
	}
    if (HBLK_IS_FREE(candidate_hdr)) return(0);
    /* Make sure r points to the beginning of the object */
	r = (ptr_t)((word)r & ~(WORDS_TO_BYTES(1) - 1));
        {
	    size_t offset = HBLKDISPL(r);
	    signed_word sz = candidate_hdr -> hb_sz;
	    size_t obj_displ = offset % sz;

	    r -= obj_displ;
            limit = r + sz;
	    if (limit > (ptr_t)(h + 1) && sz <= HBLKSIZE) {
	        return(0);
	    }
	    if ((ptr_t)p >= limit) return(0);
	}
    return((void *)r);
}


/* Return the size of an object, given a pointer to its base.		*/
/* (For small obects this also happens to work from interior pointers,	*/
/* but that shouldn't be relied upon.)					*/
size_t GC_size(void * p)
{
    hdr * hhdr = HDR(p);
    
    return hhdr -> hb_sz;
}

size_t GC_get_heap_size(void)
{
    return GC_heapsize;
}

size_t GC_get_free_bytes(void)
{
    return GC_large_free_bytes;
}

size_t GC_get_bytes_since_gc(void)
{