mf-runtime.c   [plain text]

/* Mudflap: narrow-pointer bounds-checking by tree rewriting.
   Copyright (C) 2002, 2003 Free Software Foundation, Inc.
   Contributed by Frank Ch. Eigler <fche@redhat.com>
   and Graydon Hoare <graydon@redhat.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file.  (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include "config.h"

/* These attempt to coax various unix flavours to declare all our
   needed tidbits in the system headers.  */
#if !defined(__FreeBSD__)
#define _POSIX_SOURCE
#endif /* Some BSDs break <sys/socket.h> if this is defined. */
#define _GNU_SOURCE 
#define _XOPEN_SOURCE
#define _BSD_TYPES
#define __EXTENSIONS__
#define _ALL_SOURCE
#define _LARGE_FILE_API
#define _XOPEN_SOURCE_EXTENDED 1

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#ifdef HAVE_EXECINFO_H
#include <execinfo.h>
#endif
#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif
#include <assert.h>

#include <string.h>
#include <limits.h>
#include <sys/types.h>
#include <signal.h>
#include <errno.h>

#include "mf-runtime.h"
#include "mf-impl.h"


/* ------------------------------------------------------------------------ */
/* Utility macros */

#define CTOR  __attribute__ ((constructor))
#define DTOR  __attribute__ ((destructor))


/* Codes to describe the context in which a violation occurs. */
#define __MF_VIOL_UNKNOWN 0
#define __MF_VIOL_READ 1
#define __MF_VIOL_WRITE 2
#define __MF_VIOL_REGISTER 3
#define __MF_VIOL_UNREGISTER 4
#define __MF_VIOL_WATCH 5

/* Protect against recursive calls. */
#define BEGIN_RECURSION_PROTECT() do { \
  if (UNLIKELY (__mf_state == reentrant)) { \
    write (2, "mf: erroneous reentrancy detected in `", 38); \
    write (2, __PRETTY_FUNCTION__, strlen(__PRETTY_FUNCTION__)); \
    write (2, "'\n", 2); \
    abort (); } \
  __mf_state = reentrant;  \
  } while (0)

#define END_RECURSION_PROTECT() do { \
  __mf_state = active; \
  } while (0)



/* ------------------------------------------------------------------------ */
/* Required globals.  */

#define LOOKUP_CACHE_MASK_DFL 1023
#define LOOKUP_CACHE_SIZE_MAX 4096 /* Allows max CACHE_MASK 0x0FFF */
#define LOOKUP_CACHE_SHIFT_DFL 2

struct __mf_cache __mf_lookup_cache [LOOKUP_CACHE_SIZE_MAX];
uintptr_t __mf_lc_mask = LOOKUP_CACHE_MASK_DFL;
unsigned char __mf_lc_shift = LOOKUP_CACHE_SHIFT_DFL;
#define LOOKUP_CACHE_SIZE (__mf_lc_mask + 1)

struct __mf_options __mf_opts;

int __mf_starting_p = 1;
#ifndef LIBMUDFLAPTH
enum __mf_state_enum __mf_state = active;
#else
/* See __mf_state_perthread() in mf-hooks.c. */
#endif


#ifdef LIBMUDFLAPTH
pthread_mutex_t __mf_biglock =
#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
       PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;
#else
       PTHREAD_MUTEX_INITIALIZER;
#endif
#endif

/* Use HAVE_PTHREAD_H here instead of LIBMUDFLAPTH, so that even
   the libmudflap.la (no threading support) can diagnose whether
   the application is linked with -lpthread.  See __mf_usage() below.  */
#if HAVE_PTHREAD_H
#pragma weak pthread_join
const void *threads_active_p = (void *) pthread_join;
#endif


/* ------------------------------------------------------------------------ */
/* stats-related globals.  */

static unsigned long __mf_count_check;
static unsigned long __mf_lookup_cache_reusecount [LOOKUP_CACHE_SIZE_MAX];
static unsigned long __mf_treerot_left, __mf_treerot_right;
static unsigned long __mf_count_register;
static unsigned long __mf_total_register_size [__MF_TYPE_MAX+1];
static unsigned long __mf_count_unregister;
static unsigned long __mf_total_unregister_size;
static unsigned long __mf_count_violation [__MF_VIOL_WATCH+1];
static unsigned long __mf_sigusr1_received;
static unsigned long __mf_sigusr1_handled;
/* not static */ unsigned long __mf_reentrancy;
#ifdef LIBMUDFLAPTH
/* not static */ unsigned long __mf_lock_contention;
#endif


/* ------------------------------------------------------------------------ */
/* mode-check-related globals.  */

typedef struct __mf_object
{
  uintptr_t low, high; /* __mf_register parameters */
  const char *name;
  char type; /* __MF_TYPE_something */
  char watching_p; /* Trigger a VIOL_WATCH on access? */
  unsigned read_count; /* Number of times __mf_check/read was called on this object.  */
  unsigned write_count; /* Likewise for __mf_check/write.  */
  unsigned liveness; /* A measure of recent checking activity.  */
  unsigned description_epoch; /* Last epoch __mf_describe_object printed this.  */

  uintptr_t alloc_pc;
  struct timeval alloc_time;
  char **alloc_backtrace;
  size_t alloc_backtrace_size;
#ifdef LIBMUDFLAPTH
  pthread_t alloc_thread;
#endif

  int deallocated_p;
  uintptr_t dealloc_pc;
  struct timeval dealloc_time;
  char **dealloc_backtrace;
  size_t dealloc_backtrace_size;
#ifdef LIBMUDFLAPTH
  pthread_t dealloc_thread;
#endif
} __mf_object_t;


typedef struct __mf_object_tree
{
  __mf_object_t data;
  struct __mf_object_tree *left;
  struct __mf_object_tree *right;
} __mf_object_tree_t;

/* Live objects: binary tree on __mf_object_t.low */
static __mf_object_tree_t *__mf_object_root;

/* Dead objects: circular arrays; _MIN_CEM .. _MAX_CEM only */
static unsigned __mf_object_dead_head[__MF_TYPE_MAX_CEM+1]; /* next empty spot */
static __mf_object_tree_t *__mf_object_cemetary[__MF_TYPE_MAX_CEM+1][__MF_PERSIST_MAX];


/* ------------------------------------------------------------------------ */
/* Forward function declarations */

static void __mf_init () CTOR;
static void __mf_sigusr1_respond ();
static unsigned __mf_find_objects (uintptr_t ptr_low, uintptr_t ptr_high, 
				   __mf_object_tree_t **objs, unsigned max_objs);
static unsigned __mf_find_dead_objects (uintptr_t ptr_low, uintptr_t ptr_high, 
					__mf_object_tree_t **objs, unsigned max_objs);
static void __mf_link_object (__mf_object_tree_t *obj);
static void __mf_age_tree (__mf_object_tree_t *obj);
static void __mf_adapt_cache ();
static void __mf_unlink_object (__mf_object_tree_t *obj);
static void __mf_describe_object (__mf_object_t *obj);
static unsigned __mf_watch_or_not (void *ptr, size_t sz, char flag);



/* ------------------------------------------------------------------------ */
/* Configuration engine */

static void
__mf_set_default_options ()
{
  memset (& __mf_opts, 0, sizeof (__mf_opts));

  __mf_opts.tree_aging =    13037;
  __mf_opts.adapt_cache = 1000003;
  __mf_opts.abbreviate = 1;
  __mf_opts.verbose_violations = 1;
  __mf_opts.free_queue_length = 4;
  __mf_opts.persistent_count = 100;
  __mf_opts.crumple_zone = 32;
  __mf_opts.backtrace = 4;
  __mf_opts.mudflap_mode = mode_check;
  __mf_opts.violation_mode = viol_nop;
  __mf_opts.heur_std_data = 1;
#ifdef LIBMUDFLAPTH
  __mf_opts.thread_stack = 0;
#endif
}

static struct option
{
  char *name;
  char *description;
  enum
    {
      set_option,
      read_integer_option,
    } type;
  int value;
  int *target;
} 
options [] =
  {
    {"mode-nop", 
     "mudflaps do nothing", 
     set_option, (int)mode_nop, (int *)&__mf_opts.mudflap_mode},    
    {"mode-populate", 
     "mudflaps populate object tree", 
     set_option, (int)mode_populate, (int *)&__mf_opts.mudflap_mode},    
    {"mode-check", 
     "mudflaps check for memory violations",
     set_option, (int)mode_check, (int *)&__mf_opts.mudflap_mode},
    {"mode-violate", 
     "mudflaps always cause violations (diagnostic)",
     set_option, (int)mode_violate, (int *)&__mf_opts.mudflap_mode},
   
    {"viol-nop", 
     "violations do not change program execution",
     set_option, (int)viol_nop, (int *)&__mf_opts.violation_mode},
    {"viol-abort", 
     "violations cause a call to abort()",
     set_option, (int)viol_abort, (int *)&__mf_opts.violation_mode},
    {"viol-segv", 
     "violations are promoted to SIGSEGV signals",
     set_option, (int)viol_segv, (int *)&__mf_opts.violation_mode},
    {"viol-gdb", 
     "violations fork a gdb process attached to current program",
     set_option, (int)viol_gdb, (int *)&__mf_opts.violation_mode},
    {"trace-calls", 
     "trace calls to mudflap runtime library",
     set_option, 1, &__mf_opts.trace_mf_calls},
    {"verbose-trace", 
     "trace internal events within mudflap runtime library",
     set_option, 1, &__mf_opts.verbose_trace},
    {"collect-stats", 
     "collect statistics on mudflap's operation",
     set_option, 1, &__mf_opts.collect_stats},
#if HAVE_SIGNAL
    {"sigusr1-report",
     "print report upon SIGUSR1",
     set_option, 1, &__mf_opts.sigusr1_report},
#endif
    {"internal-checking", 
     "perform more expensive internal checking",
     set_option, 1, &__mf_opts.internal_checking},
    {"age-tree", 
     "age the object tree after N accesses for working set",
     read_integer_option, 1000000, &__mf_opts.tree_aging},
    {"print-leaks", 
     "print any memory leaks at program shutdown",
     set_option, 1, &__mf_opts.print_leaks},
    {"check-initialization", 
     "detect uninitialized object reads",
     set_option, 1, &__mf_opts.check_initialization},
    {"verbose-violations", 
     "print verbose messages when memory violations occur",
     set_option, 1, &__mf_opts.verbose_violations},
    {"abbreviate", 
     "abbreviate repetitive listings",
     set_option, 1, &__mf_opts.abbreviate},
    {"wipe-stack",
     "wipe stack objects at unwind",
     set_option, 1, &__mf_opts.wipe_stack},
    {"wipe-heap",
     "wipe heap objects at free",
     set_option, 1, &__mf_opts.wipe_heap},
    {"heur-proc-map", 
     "support /proc/self/map heuristics",
     set_option, 1, &__mf_opts.heur_proc_map},
    {"heur-stack-bound",
     "enable a simple upper stack bound heuristic",
     set_option, 1, &__mf_opts.heur_stack_bound},
    {"heur-start-end", 
     "support _start.._end heuristics",
     set_option, 1, &__mf_opts.heur_start_end},
    {"heur-stdlib", 
     "register standard library data (argv, errno, stdin, ...)",
     set_option, 1, &__mf_opts.heur_std_data},
    {"free-queue-length", 
     "queue N deferred free() calls before performing them",
     read_integer_option, 0, &__mf_opts.free_queue_length},
    {"persistent-count", 
     "keep a history of N unregistered regions",
     read_integer_option, 0, &__mf_opts.persistent_count},
    {"crumple-zone", 
     "surround allocations with crumple zones of N bytes",
     read_integer_option, 0, &__mf_opts.crumple_zone},
    /* XXX: not type-safe.
    {"lc-mask", 
     "set lookup cache size mask to N (2**M - 1)",
     read_integer_option, 0, (int *)(&__mf_lc_mask)},
    {"lc-shift", 
     "set lookup cache pointer shift",
     read_integer_option, 0, (int *)(&__mf_lc_shift)},
    */
    {"lc-adapt", 
     "adapt mask/shift parameters after N cache misses",
     read_integer_option, 1, &__mf_opts.adapt_cache},
    {"backtrace", 
     "keep an N-level stack trace of each call context",
     read_integer_option, 0, &__mf_opts.backtrace},
#ifdef LIBMUDFLAPTH
    {"thread-stack", 
     "override thread stacks allocation: N kB",
     read_integer_option, 0, &__mf_opts.thread_stack},
#endif
    {0, 0, set_option, 0, NULL}
  };

static void
__mf_usage ()
{
  struct option *opt;

  fprintf (stderr, 
	   "This is a %s%sGCC \"mudflap\" memory-checked binary.\n"
	   "Mudflap is Copyright (C) 2002-2003 Free Software Foundation, Inc.\n"
	   "\n"
	   "The mudflap code can be controlled by an environment variable:\n"
	   "\n"
	   "$ export MUDFLAP_OPTIONS='<options>'\n"
	   "$ <mudflapped_program>\n"
	   "\n"
	   "where <options> is a space-separated list of \n"
	   "any of the following options.  Use `-no-OPTION' to disable options.\n"
	   "\n",
#if HAVE_PTHREAD_H
	   (threads_active_p ? "multi-threaded " : "single-threaded "),
#else
	   "",
#endif
#if LIBMUDFLAPTH
	   "thread-aware "
#else
	   "thread-unaware "
#endif
	    );
  /* XXX: The multi-threaded thread-unaware combination is bad.  */

  for (opt = options; opt->name; opt++)
    {
      int default_p = (opt->value == * opt->target);

      switch (opt->type)
	{
	  char buf[128];
	case set_option:
	  fprintf (stderr, "-%-23.23s %s", opt->name, opt->description);
	  if (default_p)
	    fprintf (stderr, " [active]\n");
	  else
	    fprintf (stderr, "\n");
	  break;
	case read_integer_option:
	  strncpy (buf, opt->name, 128);
	  strncpy (buf + strlen (opt->name), "=N", 2);
	  fprintf (stderr, "-%-23.23s %s", buf, opt->description);
	  fprintf (stderr, " [%d]\n", * opt->target);
	  break;	  
	default: abort();
	}
    }

  fprintf (stderr, "\n");
}


int 
__mf_set_options (const char *optstr)
{
  int rc;
  LOCKTH ();
  BEGIN_RECURSION_PROTECT ();
  rc = __mfu_set_options (optstr);
  /* XXX: It's not really that easy.  A change to a bunch of parameters
     can require updating auxiliary state or risk crashing: 
     free_queue_length, crumple_zone ... */
  END_RECURSION_PROTECT ();
  UNLOCKTH ();
  return rc;
}


int 
__mfu_set_options (const char *optstr)
{
  struct option *opts = 0;
  char *nxt = 0;
  long tmp = 0;
  int rc = 0;
  const char *saved_optstr = optstr;

  /* XXX: bounds-check for optstr! */

  while (*optstr)
    {
      switch (*optstr) {
      case ' ':
      case '\t':
      case '\n':
	optstr++;
	break;

      case '-':
	if (*optstr+1)
	  {	    
	    int negate = 0;
	    optstr++;

	    if (*optstr == '?' || 
		strncmp (optstr, "help", 4) == 0)
	      {
		/* Caller will print help and exit.  */
		return -1;
	      }
	    
	    if (strncmp (optstr, "no-", 3) == 0)
	      {
		negate = 1;
		optstr = & optstr[3];
	      }
	    
	    for (opts = options; opts->name; opts++)
	      {
		if (strncmp (optstr, opts->name, strlen (opts->name)) == 0)
		  {
		    optstr += strlen (opts->name);
		    assert (opts->target);
		    switch (opts->type) 
		      {
		      case set_option:
			if (negate)
			  *(opts->target) = 0;
			else
			  *(opts->target) = opts->value;
			break;
		      case read_integer_option:
			if (! negate && (*optstr == '=' && *(optstr+1)))
			  {
			    optstr++;
			    tmp = strtol (optstr, &nxt, 10);
			    if ((optstr != nxt) && (tmp != LONG_MAX))
			      {
				optstr = nxt;				
				*(opts->target) = (int)tmp;
			      }
			  }
			else if (negate)
			  * opts->target = 0;
			break;
		      }
		  }
	      }
	  }
	break;
	
      default:
	fprintf (stderr, 
		 "warning: unrecognized string '%s' in mudflap options\n",
		 optstr);
	optstr += strlen (optstr);
	rc = -1;
	break;
      }
    }

  /* Special post-processing: bound __mf_lc_mask and free_queue_length for security. */
  __mf_lc_mask &= (LOOKUP_CACHE_SIZE_MAX - 1);
  __mf_opts.free_queue_length &= (__MF_FREEQ_MAX - 1);

  /* Clear the lookup cache, in case the parameters got changed.  */
  /* XXX: race */
  memset (__mf_lookup_cache, 0, sizeof(__mf_lookup_cache));
  /* void slot 0 */
  __mf_lookup_cache[0].low = MAXPTR;

  TRACE ("set options from `%s'\n", saved_optstr);

  /* Call this unconditionally, in case -sigusr1-report was toggled. */
  __mf_sigusr1_respond ();

  return rc;
}


#ifdef PIC

void 
__mf_resolve_single_dynamic (struct __mf_dynamic_entry *e)
{
  char *err;

  assert (e);
  if (e->pointer) return;

#if HAVE_DLVSYM
  if (e->version != NULL && e->version[0] != '\0') /* non-null/empty */
    e->pointer = dlvsym (RTLD_NEXT, e->name, e->version);
  else
#endif
    e->pointer = dlsym (RTLD_NEXT, e->name);
  
  err = dlerror ();

  if (err)
    {
      fprintf (stderr, "mf: error in dlsym(\"%s\"): %s\n",
	       e->name, err);
      abort ();
    }  
  if (! e->pointer)
    {
      fprintf (stderr, "mf: dlsym(\"%s\") = NULL\n", e->name);
      abort ();
    }
}


static void 
__mf_resolve_dynamics () 
{
  int i;
  for (i = 0; i < dyn_INITRESOLVE; i++)
    __mf_resolve_single_dynamic (& __mf_dynamic[i]);
}


/* NB: order must match enums in mf-impl.h */
struct __mf_dynamic_entry __mf_dynamic [] =
{
  {NULL, "calloc", NULL},
  {NULL, "free", NULL},
  {NULL, "malloc", NULL},
  {NULL, "mmap", NULL},
  {NULL, "munmap", NULL},
  {NULL, "realloc", NULL},
  {NULL, "DUMMY", NULL}, /* dyn_INITRESOLVE */
#ifdef LIBMUDFLAPTH
  {NULL, "pthread_create", PTHREAD_CREATE_VERSION},
  {NULL, "pthread_join", NULL},
  {NULL, "pthread_exit", NULL}
#endif
};

#endif /* PIC */



/* ------------------------------------------------------------------------ */


void __mf_init ()
{
  char *ov = 0;

  /* This initial bootstrap phase requires that __mf_starting_p = 1. */
#ifdef PIC
  __mf_resolve_dynamics ();
#endif
  __mf_starting_p = 0;

  __mf_set_default_options ();

  ov = getenv ("MUDFLAP_OPTIONS");
  if (ov)
    {
      int rc = __mfu_set_options (ov);
      if (rc < 0)
	{
	  __mf_usage ();
	  exit (1);
	}
    }

  /* Initialize to a non-zero description epoch. */
  __mf_describe_object (NULL);

#define REG_RESERVED(obj) \
  __mf_register (& obj, sizeof(obj), __MF_TYPE_NOACCESS, # obj)

  REG_RESERVED (__mf_lookup_cache);
  REG_RESERVED (__mf_lc_mask);
  REG_RESERVED (__mf_lc_shift);
  /* XXX: others of our statics?  */

  /* Prevent access to *NULL. */
  __mf_register (MINPTR, 1, __MF_TYPE_NOACCESS, "NULL");
  __mf_lookup_cache[0].low = (uintptr_t) -1;
}



int
__wrap_main (int argc, char* argv[])
{
  extern char **environ;
  extern int main ();
  static int been_here = 0;

  if (__mf_opts.heur_std_data && ! been_here)
    {
      unsigned i;

      been_here = 1;
      __mf_register (argv, sizeof(char *)*(argc+1), __MF_TYPE_STATIC, "argv[]");
      for (i=0; i<argc; i++)
	{
	  unsigned j = strlen (argv[i]);
	  __mf_register (argv[i], j+1, __MF_TYPE_STATIC, "argv element");
	}

      for (i=0; ; i++)
	{
	  char *e = environ[i];
	  unsigned j;
	  if (e == NULL) break;
	  j = strlen (environ[i]);
	  __mf_register (environ[i], j+1, __MF_TYPE_STATIC, "environ element");
	}
      __mf_register (environ, sizeof(char *)*(i+1), __MF_TYPE_STATIC, "environ[]");

      __mf_register (& errno, sizeof (errno), __MF_TYPE_STATIC, "errno area");

      __mf_register (stdin,  sizeof (*stdin),  __MF_TYPE_STATIC, "stdin");
      __mf_register (stdout, sizeof (*stdout), __MF_TYPE_STATIC, "stdout");
      __mf_register (stderr, sizeof (*stderr), __MF_TYPE_STATIC, "stderr");
    }

#ifdef PIC
  return main (argc, argv, environ);
#else
  return __real_main (argc, argv, environ);
#endif
}



extern void __mf_fini () DTOR;
void __mf_fini ()
{
  TRACE ("__mf_fini\n");
  __mfu_report ();
}



/* ------------------------------------------------------------------------ */
/* __mf_check */

void __mf_check (void *ptr, size_t sz, int type, const char *location)
{
  LOCKTH ();
  BEGIN_RECURSION_PROTECT ();
  __mfu_check (ptr, sz, type, location);
  END_RECURSION_PROTECT ();
  UNLOCKTH ();
}


void __mfu_check (void *ptr, size_t sz, int type, const char *location)
{
  unsigned entry_idx = __MF_CACHE_INDEX (ptr);
  struct __mf_cache *entry = & __mf_lookup_cache [entry_idx];
  int judgement = 0; /* 0=undecided; <0=violation; >0=okay */
  uintptr_t ptr_low = (uintptr_t) ptr;
  uintptr_t ptr_high = CLAMPSZ (ptr, sz);
  struct __mf_cache old_entry = *entry;

  if (UNLIKELY (__mf_opts.sigusr1_report))
    __mf_sigusr1_respond ();

  TRACE ("check ptr=%p b=%u size=%lu %s location=`%s'\n",
	 ptr, entry_idx, (unsigned long)sz,
	 (type == 0 ? "read" : "write"), location);
  
  switch (__mf_opts.mudflap_mode)
    {
    case mode_nop:
      entry->low = MINPTR;
      entry->high = MAXPTR;
      judgement = 1;
      break;

    case mode_populate:
      entry->low = ptr_low;
      entry->high = ptr_high;
      judgement = 1;
      break;

    case mode_check:
      {
	unsigned heuristics = 0;

	/* Advance aging/adaptation counters.  */
	if (__mf_object_root)
	  {
	    static unsigned aging_count;
	    static unsigned adapt_count;
	    aging_count ++;
	    adapt_count ++;
	    if (UNLIKELY (__mf_opts.tree_aging > 0 &&
			  aging_count > __mf_opts.tree_aging))
	      {
		aging_count = 0;
		__mf_age_tree (__mf_object_root);
	      }
	    if (UNLIKELY (__mf_opts.adapt_cache > 0 &&
			  adapt_count > __mf_opts.adapt_cache))
	      {
		adapt_count = 0;
		__mf_adapt_cache ();
	      }
	  }

	/* Looping only occurs if heuristics were triggered.  */
	while (judgement == 0)
	  {
	    __mf_object_tree_t* ovr_obj[1];
	    unsigned obj_count;

	    obj_count = __mf_find_objects (ptr_low, ptr_high, ovr_obj, 1);

	    if (LIKELY (obj_count == 1)) /* A single hit! */
	      {
		__mf_object_t *obj = & ovr_obj[0]->data;
		assert (obj != NULL);
		if (LIKELY (ptr_low >= obj->low && ptr_high <= obj->high))
		  {
		    /* XXX: hope for no overflow!  */
		    if (type == __MF_CHECK_READ)
		      obj->read_count ++;
		    else
		      obj->write_count ++;

		    obj->liveness ++;
		    
		    if (UNLIKELY (obj->type == __MF_TYPE_NOACCESS))
		      judgement = -1;
		    else if (UNLIKELY (obj->watching_p))
		      judgement = -2; /* trigger VIOL_WATCH */
		    else if (UNLIKELY (__mf_opts.check_initialization
				       /* reading */
				       && type == __MF_CHECK_READ
				       /* not written */
				       && obj->write_count == 0
				       /* uninitialized (heap) */
				       && obj->type == __MF_TYPE_HEAP))
		      judgement = -1;
		    else
		      {
			/* Valid access.  */
			entry->low = obj->low;
			entry->high = obj->high;
			judgement = 1;
		      }
		  }
		/* The object did not cover the entire accessed region.  */
	      }
	    else if (LIKELY (obj_count > 1))
	      {
		__mf_object_tree_t **all_ovr_objs;
		unsigned n;
		DECLARE (void *, malloc, size_t c);
		DECLARE (void, free, void *p);

		all_ovr_objs = CALL_REAL (malloc, (sizeof (__mf_object_tree_t *) *
						   obj_count));
		if (all_ovr_objs == NULL) abort ();
		n = __mf_find_objects (ptr_low, ptr_high, all_ovr_objs, obj_count);
		assert (n == obj_count);

		/* Confirm that accessed range is covered by first/last object. */
		if (LIKELY ((ptr_low >= all_ovr_objs[0]->data.low) &&
			    (ptr_high <= all_ovr_objs[obj_count-1]->data.high)))
		  {
		    /* Presume valid access.  */
		    judgement = 1;

		    /* Confirm that intermediate objects are
		       contiguous and share a single name.  Thus they
		       are likely split up GUESS regions, or mmap
		       pages.  The idea of the name check is to
		       prevent an oversize access to a
		       stack-registered object (followed by some GUESS
		       type) from being accepted as a hit.  */
		    for (n=0; n<obj_count-1; n++)
		      {
			__mf_object_t *obj = & (all_ovr_objs[n]->data);
			__mf_object_t *nextobj = & (all_ovr_objs[n+1]->data);
			
			if (UNLIKELY (obj->type == __MF_TYPE_NOACCESS))
			  judgement = -1; /* Force error. */
			
			if (UNLIKELY (judgement == 1 &&
				      (obj->high + 1 != nextobj->low)))
			  judgement = 0; /* Cancel presumption. */
			
			if (UNLIKELY (judgement == 1 &&
				      (obj->name != nextobj->name)))
			  judgement = 0; /* Cancel presumption. */
			/* NB: strcmp above is not necessary since the
			   same literal string pointer is normally
			   used when creating regions.  */

			/* XXX: hope for no overflow!  */
			if (type == __MF_CHECK_READ)
			  obj->read_count ++;
			else
			  obj->write_count ++;
			obj->liveness ++;
		      }

		    /* If the access is otherwise successful, check whether
		       any of the covered objects are being watched.  */
		    if (judgement > 0)
		      {
			unsigned i;
			for (i=0; i<obj_count; i++)
			  if (all_ovr_objs[i]->data.watching_p)
			    judgement = -2;  /* trigger VIOL_WATCH */
		      }

		    /* Check for uninitialized reads.  */
		    if (judgement > 0 &&
			__mf_opts.check_initialization &&
			type == __MF_CHECK_READ)
		      {
			unsigned i;
			unsigned written_count = 0;

			for (i=0; i<obj_count; i++)
			  {
			    __mf_object_t *obj = & all_ovr_objs[i]->data;

			    if (obj->write_count
				|| obj->type == __MF_TYPE_HEAP_I
				|| obj->type == __MF_TYPE_GUESS)
			      written_count ++;
			  }
			
			/* Check for ALL pieces having been written-to.
			   XXX: should this be ANY instead?  */
			if (written_count != obj_count)
			  judgement = -1;
		      }

		    /* Fill out the cache with the bounds of the first
		       object and the last object that covers this
		       cache line (== includes the same __MF_CACHE_INDEX).
		       This could let this cache line span *two* distinct
		       registered objects: a peculiar but reasonable
		       situation.  The cache line may not include the
		       entire object though.  */
		    if (judgement > 0)
		      {
			unsigned i;
			entry->low = all_ovr_objs[0]->data.low;
			for (i=0; i<obj_count; i++)
			  {
			    uintptr_t high = all_ovr_objs[i]->data.high;
			    if (__MF_CACHE_INDEX (high) == entry_idx)
			      entry->high = high;
			  }
		      }
		  }

		CALL_REAL (free, all_ovr_objs);
	      }

	    if (judgement == 0)
	      {
		if (heuristics++ < 2) /* XXX parametrize this number? */
		  judgement = __mf_heuristic_check (ptr_low, ptr_high);
		else
		  judgement = -1;
	      }
	  }

      }
      break;

    case mode_violate:
      judgement = -1;
      break;
    }

  if (__mf_opts.collect_stats)
    {
      __mf_count_check ++;
      
      if (LIKELY (old_entry.low != entry->low || old_entry.high != entry->high))
	/* && (old_entry.low != 0) && (old_entry.high != 0)) */
	__mf_lookup_cache_reusecount [entry_idx] ++;    
    }
  
  if (UNLIKELY (judgement < 0))
    __mf_violation (ptr, sz,
		    (uintptr_t) __builtin_return_address (0), location,
		    ((judgement == -1) ? 
		     (type == __MF_CHECK_READ ? __MF_VIOL_READ : __MF_VIOL_WRITE) :
		     __MF_VIOL_WATCH));
}


static __mf_object_tree_t *
__mf_insert_new_object (uintptr_t low, uintptr_t high, int type, 
			const char *name, uintptr_t pc)
{
  DECLARE (void *, calloc, size_t c, size_t n);

  __mf_object_tree_t *new_obj;
  new_obj = CALL_REAL (calloc, 1, sizeof(__mf_object_tree_t));
  new_obj->data.low = low;
  new_obj->data.high = high;
  new_obj->data.type = type;
  new_obj->data.name = name;
  new_obj->data.alloc_pc = pc;
#if HAVE_GETTIMEOFDAY
  gettimeofday (& new_obj->data.alloc_time, NULL);
#endif
#if LIBMUDFLAPTH
  new_obj->data.alloc_thread = pthread_self ();
#endif

  if (__mf_opts.backtrace > 0 && (type == __MF_TYPE_HEAP || type == __MF_TYPE_HEAP_I))
    new_obj->data.alloc_backtrace_size = 
      __mf_backtrace (& new_obj->data.alloc_backtrace,
		      (void *) pc, 2);
  
  __mf_link_object (new_obj);
  return new_obj;
}


static void 
__mf_uncache_object (__mf_object_t *old_obj)
{
  /* Remove any low/high pointers for this object from the lookup cache.  */
  
  /* Can it possibly exist in the cache?  */
  if (LIKELY (old_obj->read_count + old_obj->write_count))
    {
      uintptr_t low = old_obj->low;
      uintptr_t high = old_obj->high;
      unsigned idx_low = __MF_CACHE_INDEX (low);
      unsigned idx_high = __MF_CACHE_INDEX (high);
      unsigned i;
      for (i = idx_low; i <= idx_high; i++)
	{
	  struct __mf_cache *entry = & __mf_lookup_cache [i];
	  /* NB: the "||" in the following test permits this code to
	     tolerate the situation introduced by __mf_check over
	     contiguous objects, where a cache entry spans several 
	     objects.  */
	  if (entry->low == low || entry->high == high)
	    {
	      entry->low = MAXPTR;
	      entry->high = MINPTR;
	    }
	}
    }
}


void
__mf_register (void *ptr, size_t sz, int type, const char *name)
{
  LOCKTH ();
  BEGIN_RECURSION_PROTECT ();
  __mfu_register (ptr, sz, type, name);
  END_RECURSION_PROTECT ();
  UNLOCKTH ();
}


void
__mfu_register (void *ptr, size_t sz, int type, const char *name)
{
  TRACE ("register ptr=%p size=%lu type=%x name='%s'\n", 
	 ptr, (unsigned long) sz, type, name ? name : "");

  if (__mf_opts.collect_stats)
    {
      __mf_count_register ++;
      __mf_total_register_size [(type < 0) ? 0 :
				(type > __MF_TYPE_MAX) ? 0 : 
				type] += sz;
    }

  if (UNLIKELY (__mf_opts.sigusr1_report))
    __mf_sigusr1_respond ();

  switch (__mf_opts.mudflap_mode)
    {
    case mode_nop:
      break;
      
    case mode_violate:
      __mf_violation (ptr, sz, (uintptr_t) __builtin_return_address (0), NULL,
		      __MF_VIOL_REGISTER);
      break;

    case mode_populate:
      /* Clear the cache.  */
      /* XXX: why the entire cache? */
      /* XXX: race */
      memset (__mf_lookup_cache, 0, sizeof(__mf_lookup_cache));
      /* void slot 0 */
      __mf_lookup_cache[0].low = MAXPTR;
      break;

    case mode_check:
      {
	__mf_object_tree_t *ovr_objs [1];
	unsigned num_overlapping_objs;
	uintptr_t low = (uintptr_t) ptr;
	uintptr_t high = CLAMPSZ (ptr, sz);
	uintptr_t pc = (uintptr_t) __builtin_return_address (0);
	
	/* Treat unknown size indication as 1.  */
	if (UNLIKELY (sz == 0)) sz = 1;
	
	num_overlapping_objs = __mf_find_objects (low, high, ovr_objs, 1);

	/* Handle overlaps.  */
	if (UNLIKELY (num_overlapping_objs > 0))
	  {
	    __mf_object_tree_t *ovr_obj = ovr_objs[0];
	    
	    /* Quietly accept a single duplicate registration for
	       static objects, since these may come from distinct
	       compilation units.  */
	    if (type == __MF_TYPE_STATIC
		&& ovr_obj->data.type == __MF_TYPE_STATIC
		&& ovr_obj->data.low == low
		&& ovr_obj->data.high == high)
	      {
		/* do nothing */
		VERBOSE_TRACE ("duplicate static reg %p-%p `%s'\n", 
			       (void *) low, (void *) high, 
			       (ovr_obj->data.name ? ovr_obj->data.name : ""));
		break;
	      }

	    /* Quietly accept a single duplicate registration for
	       guess objects too.  */
	    if (type == __MF_TYPE_GUESS &&
		ovr_obj->data.type == __MF_TYPE_GUESS &&
		ovr_obj->data.low == low &&
		ovr_obj->data.high == high)
	      {
		/* do nothing */
		VERBOSE_TRACE ("duplicate guess reg %p-%p\n", 
			       (void *) low, (void *) high);
		break;
	      }

	    /* Quietly accept new a guess registration that overlaps
	       at least one existing object.  Trim it down to size.  */
	    else if (type == __MF_TYPE_GUESS)
	      {
		/* We need to split this new GUESS region into some
		   smaller ones.  Or we may not need to insert it at
		   all if it is covered by the overlapping region.  */

		/* First, identify all the overlapping objects.  */
		__mf_object_tree_t **all_ovr_objs;
		unsigned num_ovr_objs, n;
		uintptr_t next_low;
		DECLARE (void *, malloc, size_t c);
		DECLARE (void, free, void *p);

		all_ovr_objs = CALL_REAL (malloc, (sizeof (__mf_object_tree_t *) *
						   num_overlapping_objs));
		if (all_ovr_objs == NULL) abort ();
		num_ovr_objs = __mf_find_objects (low, high, all_ovr_objs,
						  num_overlapping_objs);
		assert (num_ovr_objs == num_overlapping_objs);

		VERBOSE_TRACE ("splitting guess %p-%p, # overlaps: %u\n",
			       (void *) low, (void *) high, num_ovr_objs);

		/* Add GUESS regions between the holes: before each
		   overlapping region.  */

		next_low = low;
		/* This makes use of the assumption that __mf_find_objects() returns
		   overlapping objects in an increasing sequence.  */
		for (n=0; n < min (num_ovr_objs, num_overlapping_objs); n++)
		  {
		    if (all_ovr_objs[n]->data.low > next_low) /* Gap? */
		      {
			uintptr_t next_high = CLAMPSUB (all_ovr_objs[n]->data.low, 1);
			__mfu_register ((void *) next_low, next_high-next_low+1,
					__MF_TYPE_GUESS, name);
		      }
		    next_low = CLAMPADD (all_ovr_objs[n]->data.high, 1);
		  }
		/* Add in any leftover room at the top.  */
		if (next_low <= high)
		  __mfu_register ((void *) next_low, high-next_low+1,
				  __MF_TYPE_GUESS, name);

		/* XXX: future optimization: allow consecutive GUESS regions to
		   be glued together.  */
		CALL_REAL (free, all_ovr_objs);
		return;
	      }

	    /* Quietly accept a non-GUESS region overlaying a GUESS
	       region.  Handle it by removing the GUESS region
	       temporarily, then recursively adding this new object,
	       and then the GUESS back.  The latter will be split up
	       by the recursive process above.  */
	    else if (ovr_obj->data.type == __MF_TYPE_GUESS)
	      {
		uintptr_t old_low = ovr_obj->data.low;
		uintptr_t old_high = ovr_obj->data.high;
		const char* old_name = ovr_obj->data.name;

		/* Now to recursively remove the guess piece, and
  		   reinsert them in the opposite order.  Recursion
  		   should bottom out if another non-GUESS overlapping
  		   region is found for this new object (resulting in a
  		   violation), or if no further overlap occurs.  The
  		   located GUESS region should end up being split up
  		   in any case.  */
		__mfu_unregister ((void *) old_low, old_high-old_low+1);
		__mfu_register ((void *) low, sz, type, name);
		__mfu_register ((void *) old_low, old_high-old_low+1,
				__MF_TYPE_GUESS, old_name);
		return;
	      }

	    /* Alas, a genuine violation.  */
	    else
	      {
		/* Two or more *real* mappings here. */
		__mf_violation ((void *) ptr, sz,
				(uintptr_t) __builtin_return_address (0), NULL,
				__MF_VIOL_REGISTER);
	      }
	  }
	
	/* No overlapping objects: AOK.  */
	else
	  {
	    __mf_insert_new_object (low, high, type, name, pc);
	  }
	
	/* We could conceivably call __mf_check() here to prime the cache,
	   but then the read_count/write_count field is not reliable.  */
	
	break;
      }
    } /* end switch (__mf_opts.mudflap_mode) */
}


void
__mf_unregister (void *ptr, size_t sz)
{
  LOCKTH ();
  BEGIN_RECURSION_PROTECT ();
  __mfu_unregister (ptr, sz);
  END_RECURSION_PROTECT ();
  UNLOCKTH ();
}


void
__mfu_unregister (void *ptr, size_t sz)
{
  DECLARE (void, free, void *ptr);

  if (UNLIKELY (__mf_opts.sigusr1_report))
  __mf_sigusr1_respond ();

  TRACE ("unregister ptr=%p size=%lu\n", ptr, (unsigned long) sz);

  switch (__mf_opts.mudflap_mode)
    { 
    case mode_nop:
      break;

    case mode_violate:
      __mf_violation (ptr, sz,
		      (uintptr_t) __builtin_return_address (0), NULL,
		      __MF_VIOL_UNREGISTER);
      break;

    case mode_populate:
      /* Clear the cache.  */
      /* XXX: race */
      memset (__mf_lookup_cache, 0, sizeof(__mf_lookup_cache));
      /* void slot 0 */
      __mf_lookup_cache[0].low = MAXPTR;
      break;

    case mode_check:
      {
	__mf_object_tree_t *old_obj = NULL;
	__mf_object_tree_t *del_obj = NULL;  /* Object to actually delete. */
	__mf_object_tree_t *objs[1] = {NULL};
	unsigned num_overlapping_objs;
		
	/* Treat unknown size indication as 1.  */
	if (sz == 0) sz = 1;
	
	num_overlapping_objs = __mf_find_objects ((uintptr_t) ptr,
						  CLAMPSZ (ptr, sz), objs, 1);

	/* XXX: handle unregistration of big old GUESS region, that has since
	   been splintered.  */
	old_obj = objs[0];

	if (UNLIKELY (num_overlapping_objs != 1 ||
		      (uintptr_t)ptr != old_obj->data.low)) /* XXX: what about sz? */
	  {
	    __mf_violation (ptr, sz,
			    (uintptr_t) __builtin_return_address (0), NULL,
			    __MF_VIOL_UNREGISTER);
	    break;
	  }

	__mf_unlink_object (old_obj);
	__mf_uncache_object (& old_obj->data);

	/* Wipe buffer contents if desired.  */
	if ((__mf_opts.wipe_stack && old_obj->data.type == __MF_TYPE_STACK)
	    || (__mf_opts.wipe_heap && (old_obj->data.type == __MF_TYPE_HEAP 
					|| old_obj->data.type == __MF_TYPE_HEAP_I)))
	  {
	    memset ((void *) old_obj->data.low,
		    0,
		    (size_t) (old_obj->data.high - old_obj->data.low + 1));
	  }
	
	/* Manage the object cemetary.  */
	if (__mf_opts.persistent_count > 0 && 
	    old_obj->data.type >= 0 && 
	    old_obj->data.type <= __MF_TYPE_MAX_CEM)
	  {
	    old_obj->data.deallocated_p = 1;
	    old_obj->left = old_obj->right = NULL;
	    old_obj->data.dealloc_pc = (uintptr_t) __builtin_return_address (0);
#if HAVE_GETTIMEOFDAY
	    gettimeofday (& old_obj->data.dealloc_time, NULL);
#endif
#ifdef LIBMUDFLAPTH
	    old_obj->data.dealloc_thread = pthread_self ();
#endif

	    if (__mf_opts.backtrace > 0 && old_obj->data.type == __MF_TYPE_HEAP)
	      old_obj->data.dealloc_backtrace_size = 
		__mf_backtrace (& old_obj->data.dealloc_backtrace,
				NULL, 2);

	    /* Encourage this object to be displayed again in current epoch.  */
	    old_obj->data.description_epoch --;

	    /* Put this object into the cemetary.  This may require this plot to
	       be recycled, and the previous resident to be designated del_obj.  */
	    {
	      unsigned row = old_obj->data.type;
	      unsigned plot = __mf_object_dead_head [row];
	      
	      del_obj = __mf_object_cemetary [row][plot];
	      __mf_object_cemetary [row][plot] = old_obj;
	      plot ++;
	      if (plot == __mf_opts.persistent_count) plot = 0;
	      __mf_object_dead_head [row] = plot;
	    }
	  }
	else
	  del_obj = old_obj;
	
	if (__mf_opts.print_leaks)
	  {
	    if ((old_obj->data.read_count + old_obj->data.write_count) == 0 &&
		(old_obj->data.type == __MF_TYPE_HEAP 
		 || old_obj->data.type == __MF_TYPE_HEAP_I))
	      {
		fprintf (stderr, 
			 "*******\n"
			 "mudflap warning: unaccessed registered object:\n");
		__mf_describe_object (& old_obj->data);
	      }
	  }
	
	if (del_obj != NULL) /* May or may not equal old_obj.  */
	  {
	    if (__mf_opts.backtrace > 0)
	      {
		CALL_REAL(free, del_obj->data.alloc_backtrace);
		if (__mf_opts.persistent_count > 0)
		  {
		    CALL_REAL(free, del_obj->data.dealloc_backtrace);
		  }
	      }
	    CALL_REAL(free, del_obj);
	  }
	
	break;
      }
    } /* end switch (__mf_opts.mudflap_mode) */


  if (__mf_opts.collect_stats)
    {
      __mf_count_unregister ++;
      __mf_total_unregister_size += sz;
    }
}

/* ------------------------------------------------------------------------ */
/* __mf_validate_live_object_tree, _object_cemetary */

static void
__mf_validate_live_object_tree (__mf_object_tree_t *obj)
{
  assert (obj != NULL);

  if (__mf_opts.persistent_count > 0)
    assert (! obj->data.deallocated_p);

  if (obj->left)
    {
      assert (obj->left->data.high < obj->data.low);
      __mf_validate_live_object_tree (obj->left);
    }
  if (obj->right)
    {
      assert (obj->right->data.low > obj->data.high);
      __mf_validate_live_object_tree (obj->right);
    }
}

static void
__mf_validate_object_cemetary ()
{
  unsigned cls;
  unsigned i;

  for (cls = 0; cls <= __MF_TYPE_MAX_CEM; cls++)
    {
      assert (__mf_object_dead_head [cls] >= 0 &&
	      __mf_object_dead_head [cls] < __mf_opts.persistent_count);
      for (i = 0; i < __mf_opts.persistent_count; i++)
	{
	  __mf_object_tree_t *obj = __mf_object_cemetary [cls][i];
	  if (obj != NULL)
	    {
	      assert (obj->data.deallocated_p);
	      assert (obj->left == NULL);
	      assert (obj->right == NULL);
	    }
	}
    }
}

static void 
__mf_validate_objects ()
{
  if (__mf_object_root)
    __mf_validate_live_object_tree (__mf_object_root);

  if (__mf_opts.persistent_count > 0)
    __mf_validate_object_cemetary ();
}


static void
__mf_age_tree (__mf_object_tree_t *obj)
{
  assert (obj != NULL);
  obj->data.liveness = obj->data.liveness >> 1;

  if (obj->left)
    __mf_age_tree (obj->left);
  if (obj->right)
    __mf_age_tree (obj->right);
}



struct tree_stats
{
  unsigned obj_count;
  unsigned long total_size;
  unsigned live_obj_count;
  double total_weight;
  double weighted_size;
  unsigned long weighted_address_bits [sizeof (uintptr_t) * 8][2];
};


static void
__mf_tree_analyze (__mf_object_tree_t *obj, struct tree_stats* s)
{
  assert (obj != NULL);

  if (obj->left)
    __mf_tree_analyze (obj->left, s);

  /* Exclude never-accessed objects.  */
  if (obj->data.read_count + obj->data.write_count)
    {
      s->obj_count ++;
      s->total_size += (obj->data.high - obj->data.low + 1);

      if (obj->data.liveness)
	{
	  unsigned i;
	  uintptr_t addr;

	  VERBOSE_TRACE ("analyze low=%p live=%u name=`%s'\n",
			 (void *) obj->data.low, obj->data.liveness, obj->data.name);

	  s->live_obj_count ++;
	  s->total_weight += (double) obj->data.liveness;
	  s->weighted_size +=
	    (double) (obj->data.high - obj->data.low + 1) *
	    (double) obj->data.liveness;

	  addr = obj->data.low;
	  for (i=0; i<sizeof(uintptr_t) * 8; i++)
	    {
	      unsigned bit = addr & 1;
	      s->weighted_address_bits[i][bit] += obj->data.liveness;
	      addr = addr >> 1;
	    }
	}
    }

  if (obj->right)
    __mf_tree_analyze (obj->right, s);
}


static void
__mf_adapt_cache ()
{
  struct tree_stats s;
  uintptr_t new_mask = 0;
  unsigned char new_shift;
  float cache_utilization;
  float max_value;
  static float smoothed_new_shift = -1.0;
  unsigned i;

  memset (&s, 0, sizeof (s));
  if (__mf_object_root)
    __mf_tree_analyze (__mf_object_root, & s);

  /* Maybe we're dealing with funny aging/adaptation parameters, or an
     empty tree.  Just leave the cache alone in such cases, rather
     than risk dying by division-by-zero.  */
  if (! (s.obj_count > 0) && (s.live_obj_count > 0) && (s.total_weight > 0.0))
    return;

  /* Guess a good value for the shift parameter by finding an address bit that is a
     good discriminant of lively objects.  */
  max_value = 0.0;
  for (i=0; i<sizeof (uintptr_t)*8; i++)
    {
      float value = (float) s.weighted_address_bits[i][0] * (float) s.weighted_address_bits[i][1];
      if (max_value < value) max_value = value;
    }
  for (i=0; i<sizeof (uintptr_t)*8; i++)
    {
      float shoulder_factor = 0.7;  /* Include slightly less popular bits too.  */
      float value = (float) s.weighted_address_bits[i][0] * (float) s.weighted_address_bits[i][1];
      if (value >= max_value * shoulder_factor)
	break;
    }
  if (smoothed_new_shift < 0) smoothed_new_shift = __mf_lc_shift;
  /* Converge toward this slowly to reduce flapping. */  
  smoothed_new_shift = 0.9*smoothed_new_shift + 0.1*i;
  new_shift = (unsigned) (smoothed_new_shift + 0.5);
  assert (new_shift < sizeof (uintptr_t)*8);

  /* Count number of used buckets.  */
  cache_utilization = 0.0;
  for (i = 0; i < (1 + __mf_lc_mask); i++)
    if (__mf_lookup_cache[i].low != 0 || __mf_lookup_cache[i].high != 0)
      cache_utilization += 1.0;
  cache_utilization /= (1 + __mf_lc_mask);

  new_mask |= 0x3ff; /* XXX: force a large cache.  */
  new_mask &= (LOOKUP_CACHE_SIZE_MAX - 1);

  VERBOSE_TRACE ("adapt cache obj=%u/%u sizes=%lu/%.0f/%.0f => "
		 "util=%u%% m=%p s=%u\n",
		 s.obj_count, s.live_obj_count, s.total_size, s.total_weight, s.weighted_size,
		 (unsigned)(cache_utilization*100.0), (void *) new_mask, new_shift);

  /* We should reinitialize cache if its parameters have changed.  */
  if (new_mask != __mf_lc_mask ||
      new_shift != __mf_lc_shift)
    {
      __mf_lc_mask = new_mask;
      __mf_lc_shift = new_shift;
      /* XXX: race */
      memset (__mf_lookup_cache, 0, sizeof(__mf_lookup_cache));
      /* void slot 0 */
      __mf_lookup_cache[0].low = MAXPTR;
    }
}




/* __mf_find_object[s] */

/* Find overlapping live objecs between [low,high].  Return up to
   max_objs of their pointers in objs[].  Return total count of
   overlaps (may exceed max_objs). */

/* XXX: track traversal statistics, like average depth, balance.  */

static unsigned
__mf_find_objects_rec (uintptr_t low, uintptr_t high, __mf_object_tree_t **nodep,
		       __mf_object_tree_t **objs, unsigned max_objs)
{
  unsigned count;
  __mf_object_tree_t *node = *nodep;

  assert (low <= high);
  assert (max_objs == 0 || objs != NULL);

  if (UNLIKELY (node == NULL)) return 0;

  /* Traverse down left subtree. */
  count = 0;
  if (low < node->data.low)
    count += __mf_find_objects_rec (low, min(high, node->data.low),
				    & node->left, objs, max_objs);

  /* Track the used slots of objs[].  */
  if (count < max_objs)
    {
      objs += count;
      max_objs -= count;
    }
  else
    {
      max_objs = 0;
    }

  /* Check for overlap with this node.  */
  if (high >= node->data.low && low <= node->data.high)
    {
      count ++;
      if (max_objs > 0)  /* Any room left?  */
	{
	  objs[0] = node;
	  objs ++;
	  max_objs --;
	}
    }

  /* Traverse down right subtree.  */
  if (high > node->data.high)
    count += __mf_find_objects_rec (max (low, node->data.high), high,
				    & node->right, objs, max_objs);
  /* There is no need to manipulate objs/max_objs any further.  */


  /* Rotate a child node up if its access count is higher. */
  if (UNLIKELY ((node->left && node->left->data.liveness > node->data.liveness) &&
		((!node->right || (node->right && 
				   node->left->data.liveness > 
				   node->right->data.liveness)))))
    {
      __mf_object_tree_t *l = node->left;
      __mf_object_tree_t *l_r = l->right;

      *nodep = l;
      l->right = node;
      node->left = l_r;
      __mf_treerot_left ++;
    }
  else if (UNLIKELY ((node->right && node->right->data.liveness > node->data.liveness) &&
		     ((!node->left || (node->left && 
				       node->right->data.liveness > 
				       node->left->data.liveness)))))
    {
      __mf_object_tree_t *r = node->right;
      __mf_object_tree_t *r_l = r->left;

      *nodep = r;
      r->left = node;
      node->right = r_l;
      __mf_treerot_right ++;
    }

  return count;
}


unsigned
__mf_find_objects (uintptr_t ptr_low, uintptr_t ptr_high,
		   __mf_object_tree_t **objs, unsigned max_objs)
{
  if (UNLIKELY(__mf_opts.internal_checking))
    __mf_validate_objects ();

  return __mf_find_objects_rec (ptr_low, ptr_high, & __mf_object_root, objs, max_objs);
}

/* __mf_link_object */

static void
__mf_link_object2 (__mf_object_tree_t *ptr, __mf_object_tree_t **link)
{
  __mf_object_tree_t *node = *link;

  assert (ptr != NULL);
  if (UNLIKELY(node == NULL))
    {
      *link = ptr;
      return;
    }

  if (ptr->data.high < node->data.low)
    return __mf_link_object2 (ptr, & node->left);
  else if (ptr->data.low > node->data.high)
    return __mf_link_object2 (ptr, & node->right);
  else
    abort (); /* XXX: duplicate object */
}


void
__mf_link_object (__mf_object_tree_t *ptr)
{
  if (UNLIKELY(__mf_opts.internal_checking))
    __mf_validate_objects ();

  return __mf_link_object2 (ptr, & __mf_object_root);
}

/* __mf_unlink_object */

static void
__mf_unlink_object2 (__mf_object_tree_t *ptr, __mf_object_tree_t **link)
{
  __mf_object_tree_t *node = *link;
  
  assert (ptr != NULL);
  if (UNLIKELY(node == ptr))
    {
      static unsigned promote_left_p = 0;
      promote_left_p = 1 - promote_left_p;

      /* Alternate promoting the left & right subtrees. */
      if (promote_left_p)
	{
	  *link = ptr->left;
	  if (ptr->right != NULL)
	    __mf_link_object2 (ptr->right, link);
	}
      else
	{
	  *link = ptr->right;
	  if (ptr->left != NULL)
	    __mf_link_object2 (ptr->left, link);
	}

      return;
    }

  if (ptr->data.high < node->data.low)
    return __mf_unlink_object2 (ptr, & node->left);
  else if (ptr->data.low > node->data.high)
    return __mf_unlink_object2 (ptr, & node->right);
  else
    abort (); /* XXX: missing object; should fail more gracefully. */
}

static void
__mf_unlink_object (__mf_object_tree_t *node)
{
  __mf_unlink_object2 (node, & __mf_object_root);
}

/* __mf_find_dead_objects */

/* Find overlapping dead objecs between [low,high].  Return up to
   max_objs of their pointers in objs[].  Return total count of
   overlaps (may exceed max_objs).  */

static unsigned
__mf_find_dead_objects (uintptr_t low, uintptr_t high,
			__mf_object_tree_t **objs, unsigned max_objs)
{
  if (__mf_opts.persistent_count > 0)
    {
      unsigned count = 0;
      unsigned recollection = 0;
      unsigned row = 0;
      
      assert (low <= high);
      assert (max_objs == 0 || objs != NULL);
      
      /* Widen the search from the most recent plots in each row, looking
	 backward in time.  */
      recollection = 0;
      while (recollection < __mf_opts.persistent_count)
	{
	  count = 0;
	  
	  for (row = 0; row <= __MF_TYPE_MAX_CEM; row ++)
	    {
	      unsigned plot;
	      unsigned i;
	      
	      plot = __mf_object_dead_head [row];
	      for (i = 0; i <= recollection; i ++)
		{
		  __mf_object_tree_t *obj;
		  
		  /* Look backward through row: it's a circular buffer.  */
		  if (plot > 0) plot --;
		  else plot = __mf_opts.persistent_count - 1;
		  
		  obj = __mf_object_cemetary [row][plot];
		  if (obj && obj->data.low <= high && obj->data.high >= low)
		    {
		      /* Found an overlapping dead object!  */
		      if (count < max_objs)
			objs [count] = obj;
		      count ++;
		    }
		}
	    }
	  
	  if (count)
	    break;
	  
	  /* Look farther back in time.  */
	  recollection = (recollection * 2) + 1;
	}
      
      return count;
    } else {
      return 0;
    }
}

/* __mf_describe_object */

static void
__mf_describe_object (__mf_object_t *obj)
{
  static unsigned epoch = 0;
  if (obj == NULL)
    {
      epoch ++;
      return;
    }

  if (__mf_opts.abbreviate && obj->description_epoch == epoch)
    {
      fprintf (stderr,
	       "mudflap object %p: name=`%s'\n",
	       (void *) obj, (obj->name ? obj->name : ""));
      return;
    }
  else
    obj->description_epoch = epoch;

  fprintf (stderr,
	   "mudflap object %p: name=`%s'\n"
	   "bounds=[%p,%p] size=%lu area=%s check=%ur/%uw liveness=%u%s\n"
	   "alloc time=%lu.%06lu pc=%p"
#ifdef LIBMUDFLAPTH
	   " thread=%u"
#endif
	   "\n",
	   (void *) obj, (obj->name ? obj->name : ""), 
	   (void *) obj->low, (void *) obj->high,
	   (unsigned long) (obj->high - obj->low + 1),
	   (obj->type == __MF_TYPE_NOACCESS ? "no-access" :
	    obj->type == __MF_TYPE_HEAP ? "heap" :
	    obj->type == __MF_TYPE_HEAP_I ? "heap-init" :
	    obj->type == __MF_TYPE_STACK ? "stack" :
	    obj->type == __MF_TYPE_STATIC ? "static" :
	    obj->type == __MF_TYPE_GUESS ? "guess" :
	    "unknown"),
	   obj->read_count, obj->write_count, obj->liveness, 
	   obj->watching_p ? " watching" : "",
	   obj->alloc_time.tv_sec, obj->alloc_time.tv_usec, 
	   (void *) obj->alloc_pc
#ifdef LIBMUDFLAPTH
	   , (unsigned) obj->alloc_thread
#endif
	   );

  if (__mf_opts.backtrace > 0)
  {
    unsigned i;
    for (i=0; i<obj->alloc_backtrace_size; i++)
      fprintf (stderr, "      %s\n", obj->alloc_backtrace[i]);
  }

  if (__mf_opts.persistent_count > 0)
    {
      if (obj->deallocated_p)
	{
	  fprintf (stderr, "dealloc time=%lu.%06lu pc=%p"
#ifdef LIBMUDFLAPTH
		   " thread=%u"
#endif
		   "\n",
		   obj->dealloc_time.tv_sec, obj->dealloc_time.tv_usec, 
		   (void *) obj->dealloc_pc
#ifdef LIBMUDFLAPTH
		   , (unsigned) obj->dealloc_thread
#endif
		   );


	  if (__mf_opts.backtrace > 0)
	  {
	    unsigned i;
	    for (i=0; i<obj->dealloc_backtrace_size; i++)
	      fprintf (stderr, "      %s\n", obj->dealloc_backtrace[i]);
	  }
	}
    }
}

static unsigned
__mf_report_leaks (__mf_object_tree_t *node)
{
 /* The counter is amongst recursive calls, so
    that cumulative numbers are printed below.  */
  static unsigned count = 0;

  if (node == NULL)  /* Reset */
    {
      count = 0;
      return 0;
    }

  /* Inorder traversal. */
  if (node->left)
    __mf_report_leaks (node->left);
  if (node->data.type == __MF_TYPE_HEAP
      || node->data.type == __MF_TYPE_HEAP_I)
    {
      count ++;
      fprintf (stderr, "Leaked object %u:\n", count);
      __mf_describe_object (& node->data);
    }
  if (node->right)
    __mf_report_leaks (node->right);

  return count;
}

/* ------------------------------------------------------------------------ */
/* __mf_report */

void
__mf_report ()
{
  LOCKTH ();
  BEGIN_RECURSION_PROTECT ();
  __mfu_report ();
  END_RECURSION_PROTECT ();
  UNLOCKTH ();
}

void
__mfu_report ()
{
  if (__mf_opts.collect_stats)
    {
      fprintf (stderr,
	       "*******\n"
	       "mudflap stats:\n"
	       "calls to __mf_check: %lu rot: %lu/%lu\n"
	       "         __mf_register: %lu [%luB, %luB, %luB, %luB, %luB]\n"
	       "         __mf_unregister: %lu [%luB]\n"
	       "         __mf_violation: [%lu, %lu, %lu, %lu, %lu]\n",
	       __mf_count_check, __mf_treerot_left, __mf_treerot_right,
	       __mf_count_register,
	       __mf_total_register_size[0], __mf_total_register_size[1],
	       __mf_total_register_size[2], __mf_total_register_size[3],
	       __mf_total_register_size[4], /* XXX */
	       __mf_count_unregister, __mf_total_unregister_size,
	       __mf_count_violation[0], __mf_count_violation[1],
	       __mf_count_violation[2], __mf_count_violation[3],
	       __mf_count_violation[4]);

      fprintf (stderr,
	       "calls with reentrancy: %lu\n", __mf_reentrancy);
#ifdef LIBMUDFLAPTH
      fprintf (stderr,
	       "           lock contention: %lu\n", __mf_lock_contention);
#endif

      /* Lookup cache stats.  */
      {
	unsigned i;
	unsigned max_reuse = 0;
	unsigned num_used = 0;
	unsigned num_unused = 0;

	for (i = 0; i < LOOKUP_CACHE_SIZE; i++)
	  {
	    if (__mf_lookup_cache_reusecount[i])
	      num_used ++;
	    else
	      num_unused ++;
	    if (max_reuse < __mf_lookup_cache_reusecount[i])
	      max_reuse = __mf_lookup_cache_reusecount[i];
	  }
	fprintf (stderr, "lookup cache slots used: %u  unused: %u  peak-reuse: %u\n",
		 num_used, num_unused, max_reuse);
      }

      {
	unsigned live_count;
	live_count = __mf_find_objects (MINPTR, MAXPTR, NULL, 0);
	fprintf (stderr, "number of live objects: %u\n", live_count);
      }

      if (__mf_opts.persistent_count > 0)
	{
	  unsigned dead_count = 0;
	  unsigned row, plot;
	  for (row = 0; row <= __MF_TYPE_MAX_CEM; row ++)
	    for (plot = 0 ; plot < __mf_opts.persistent_count; plot ++)
	      if (__mf_object_cemetary [row][plot] != 0)
		dead_count ++;
	  fprintf (stderr, "          zombie objects: %u\n", dead_count);
	}
    }
  if (__mf_opts.print_leaks && (__mf_opts.mudflap_mode == mode_check))
    {
      unsigned l;
      extern void * __mf_wrap_alloca_indirect (size_t c);

      /* Free up any remaining alloca()'d blocks.  */
      __mf_wrap_alloca_indirect (0);
      __mf_describe_object (NULL); /* Reset description epoch.  */
      __mf_report_leaks (NULL); /* Reset cumulative count.  */
      l = __mf_report_leaks (__mf_object_root);
      fprintf (stderr, "number of leaked objects: %u\n", l);
    }
}

/* __mf_backtrace */

size_t
__mf_backtrace (char ***symbols, void *guess_pc, unsigned guess_omit_levels)
{
  void ** pc_array;
  unsigned pc_array_size = __mf_opts.backtrace + guess_omit_levels;
  unsigned remaining_size;
  unsigned omitted_size = 0;
  unsigned i;
  DECLARE (void, free, void *ptr);
  DECLARE (void *, calloc, size_t c, size_t n);
  DECLARE (void *, malloc, size_t n);

  pc_array = CALL_REAL (calloc, pc_array_size, sizeof (void *) );
#ifdef HAVE_BACKTRACE
  pc_array_size = backtrace (pc_array, pc_array_size);
#else
#define FETCH(n) do { if (pc_array_size >= n) { \
                 pc_array[n] = __builtin_return_address(n); \
                 if (pc_array[n] == 0) pc_array_size = n; } } while (0)

  /* Unroll some calls __builtin_return_address because this function
     only takes a literal integer parameter.  */
  FETCH (0);
#if 0
  /* XXX: __builtin_return_address sometimes crashes (!) on >0 arguments,
     rather than simply returning 0.  :-(  */
  FETCH (1);
  FETCH (2);
  FETCH (3);
  FETCH (4);
  FETCH (5);
  FETCH (6);
  FETCH (7);
  FETCH (8);
  if (pc_array_size > 8) pc_array_size = 9;
#else
  if (pc_array_size > 0) pc_array_size = 1;
#endif

#undef FETCH
#endif

  /* We want to trim the first few levels of the stack traceback,
     since they contain libmudflap wrappers and junk.  If pc_array[]
     ends up containing a non-NULL guess_pc, then trim everything
     before that.  Otherwise, omit the first guess_omit_levels
     entries. */
  
  if (guess_pc != NULL)
    for (i=0; i<pc_array_size; i++)
      if (pc_array [i] == guess_pc)
	omitted_size = i;

  if (omitted_size == 0) /* No match? */
    if (pc_array_size > guess_omit_levels)
      omitted_size = guess_omit_levels;

  remaining_size = pc_array_size - omitted_size;

#ifdef HAVE_BACKTRACE_SYMBOLS
  *symbols = backtrace_symbols (pc_array + omitted_size, remaining_size);
#else
  {
    /* Let's construct a buffer by hand.  It will have <remaining_size>
       char*'s at the front, pointing at individual strings immediately
       afterwards.  */
    void *buffer;
    char *chars;
    char **pointers;
    enum { perline = 30 };
    buffer = CALL_REAL (malloc, remaining_size * (perline + sizeof(char *)));
    pointers = (char **) buffer;
    chars = (char *)buffer + (remaining_size * sizeof (char *));
    for (i = 0; i < remaining_size; i++)
      {
	pointers[i] = chars;
	sprintf (chars, "[0x%p]", pc_array [omitted_size + i]);
	chars = chars + perline;
      }
    *symbols = pointers;
  }
#endif
  CALL_REAL (free, pc_array);

  return remaining_size;
}

/* ------------------------------------------------------------------------ */
/* __mf_violation */

void
__mf_violation (void *ptr, size_t sz, uintptr_t pc, 
		const char *location, int type)
{
  char buf [128];
  static unsigned violation_number;
  DECLARE(void, free, void *ptr);

  TRACE ("violation pc=%p location=%s type=%d ptr=%p size=%lu\n", 
	 (void *) pc, 
	 (location != NULL ? location : ""), type, ptr, (unsigned long) sz);

  if (__mf_opts.collect_stats)
    __mf_count_violation [(type < 0) ? 0 :
			  (type > __MF_VIOL_WATCH) ? 0 :
			  type] ++;

  /* Print out a basic warning message.  */
  if (__mf_opts.verbose_violations)
  {
    unsigned dead_p;
    unsigned num_helpful = 0;
    struct timeval now;
#if HAVE_GETTIMEOFDAY
    gettimeofday (& now, NULL);
#endif

    violation_number ++;
    fprintf (stderr,
	     "*******\n"
	     "mudflap violation %u (%s): time=%lu.%06lu "
	     "ptr=%p size=%lu\npc=%p%s%s%s\n", 
	     violation_number,
	     ((type == __MF_VIOL_READ) ? "check/read" :
	      (type == __MF_VIOL_WRITE) ? "check/write" :
	      (type == __MF_VIOL_REGISTER) ? "register" :
	      (type == __MF_VIOL_UNREGISTER) ? "unregister" :
	      (type == __MF_VIOL_WATCH) ? "watch" : "unknown"),
	     now.tv_sec, now.tv_usec, 
	     (void *) ptr, (unsigned long)sz, (void *) pc,
	     (location != NULL ? " location=`" : ""),
	     (location != NULL ? location : ""),
	     (location != NULL ? "'" : ""));

    if (__mf_opts.backtrace > 0)
      {
	char ** symbols;
	unsigned i, num;
	
	num = __mf_backtrace (& symbols, (void *) pc, 2);
	/* Note: backtrace_symbols calls malloc().  But since we're in
	   __mf_violation and presumably __mf_check, it'll detect
	   recursion, and not put the new string into the database.  */
	
	for (i=0; i<num; i++)
	  fprintf (stderr, "      %s\n", symbols[i]);
	
	/* Calling free() here would trigger a violation.  */
	CALL_REAL(free, symbols);
      }
    
    
    /* Look for nearby objects.  For this, we start with s_low/s_high
       pointing to the given area, looking for overlapping objects.
       If none show up, widen the search area and keep looking. */
    
    if (sz == 0) sz = 1;
    
    for (dead_p = 0; dead_p <= 1; dead_p ++) /* for dead_p in 0 1 */
      {
	enum {max_objs = 3}; /* magic */
	__mf_object_tree_t *objs[max_objs];
	unsigned num_objs = 0;
	uintptr_t s_low, s_high;
	unsigned tries = 0;
	unsigned i;
	
	s_low = (uintptr_t) ptr;
	s_high = CLAMPSZ (ptr, sz);

	while (tries < 16) /* magic */
	  {
	    if (dead_p)
	      num_objs = __mf_find_dead_objects (s_low, s_high, objs, max_objs);
	    else
	      num_objs = __mf_find_objects (s_low, s_high, objs, max_objs);

	    if (num_objs) /* good enough */
	      break;

	    tries ++;

	    /* XXX: tune this search strategy.  It's too dependent on
	     sz, which can vary from 1 to very big (when array index
	     checking) numbers. */
	    s_low = CLAMPSUB (s_low, (sz * tries * tries));
	    s_high = CLAMPADD (s_high, (sz * tries * tries));
	  }

	for (i = 0; i < min (num_objs, max_objs); i++)
	  {
	    __mf_object_t *obj = & objs[i]->data;
	    uintptr_t low = (uintptr_t) ptr;
	    uintptr_t high = CLAMPSZ (ptr, sz);
	    unsigned before1 = (low < obj->low) ? obj->low - low : 0;
	    unsigned after1 = (low > obj->high) ? low - obj->high : 0;
	    unsigned into1 = (high >= obj->low && low <= obj->high) ? low - obj->low : 0;
	    unsigned before2 = (high < obj->low) ? obj->low - high : 0;
	    unsigned after2 = (high > obj->high) ? high - obj->high : 0;
	    unsigned into2 = (high >= obj->low && low <= obj->high) ? high - obj->low : 0;

	    fprintf (stderr, "Nearby object %u: checked region begins %uB %s and ends %uB %s\n",
		     num_helpful + i + 1,
		     (before1 ? before1 : after1 ? after1 : into1),
		     (before1 ? "before" : after1 ? "after" : "into"),
		     (before2 ? before2 : after2 ? after2 : into2),
		     (before2 ? "before" : after2 ? "after" : "into"));
	    __mf_describe_object (obj);
	  }
	num_helpful += num_objs;
      }

    fprintf (stderr, "number of nearby objects: %u\n", num_helpful);
  }

  /* How to finally handle this violation?  */
  switch (__mf_opts.violation_mode)
    {
    case viol_nop:
      break;
    case viol_segv:
      kill (getpid(), SIGSEGV);
      break;
    case viol_abort:
      abort ();
      break;
    case viol_gdb:
      snprintf (buf, 128, "gdb --pid=%d", getpid ());
      system (buf);
      /* XXX: should probably fork() && sleep(GDB_WAIT_PARAMETER)
      instead, and let the forked child execlp() gdb.  That way, this
      subject process can be resumed under the supervision of gdb.
      This can't happen now, since system() only returns when gdb
      dies.  In that case, we need to beware of starting a second
      concurrent gdb child upon the next violation.  (But if the first
      gdb dies, then starting a new one is appropriate.)  */
      break;
    }
}

/* ------------------------------------------------------------------------ */


unsigned __mf_watch (void *ptr, size_t sz)
{
  unsigned rc;
  LOCKTH ();
  BEGIN_RECURSION_PROTECT ();
  rc = __mf_watch_or_not (ptr, sz, 1);
  END_RECURSION_PROTECT ();
  UNLOCKTH ();
  return rc;
}

unsigned __mf_unwatch (void *ptr, size_t sz)
{
  unsigned rc;
  LOCKTH ();
  rc = __mf_watch_or_not (ptr, sz, 0);
  UNLOCKTH ();
  return rc;
}


static unsigned
__mf_watch_or_not (void *ptr, size_t sz, char flag)
{
  uintptr_t ptr_high = CLAMPSZ (ptr, sz);
  uintptr_t ptr_low = (uintptr_t) ptr;
  unsigned count = 0;

  TRACE ("%s ptr=%p size=%lu\n",
	 (flag ? "watch" : "unwatch"), ptr, (unsigned long) sz);
  
  switch (__mf_opts.mudflap_mode)
    {
    case mode_nop:
    case mode_populate:
    case mode_violate:
      count = 0;
      break;

    case mode_check:
      {
	__mf_object_tree_t **all_ovr_objs;
	unsigned obj_count;
	unsigned n;
	DECLARE (void *, malloc, size_t c);
	DECLARE (void, free, void *p);

	obj_count = __mf_find_objects (ptr_low, ptr_high, NULL, 0);
	VERBOSE_TRACE (" %u:", obj_count);

	all_ovr_objs = CALL_REAL (malloc, (sizeof (__mf_object_tree_t *) *
					   obj_count));
	if (all_ovr_objs == NULL) abort ();
	n = __mf_find_objects (ptr_low, ptr_high, all_ovr_objs, obj_count);
	assert (n == obj_count);

	for (n = 0; n < obj_count; n ++)
	  {
	    __mf_object_t *obj = & (all_ovr_objs[n]->data);

	    VERBOSE_TRACE (" [%p]", (void *) obj);
	    if (obj->watching_p != flag)
	      {
		obj->watching_p = flag;
		count ++;

		/* Remove object from cache, to ensure next access
		   goes through __mf_check().  */
	        if (flag)
		  __mf_uncache_object (obj);
	      }
	  }
	CALL_REAL (free, all_ovr_objs);
      }
      break;
    }

  return count;
}


void
__mf_sigusr1_handler (int num)
{
  __mf_sigusr1_received ++;
}

/* Install or remove SIGUSR1 handler as necessary.
   Also, respond to a received pending SIGUSR1.  */
void
__mf_sigusr1_respond ()
{
  static int handler_installed;

#if HAVE_SIGNAL
  /* Manage handler */
  if (__mf_opts.sigusr1_report && ! handler_installed)
    {
      signal (SIGUSR1, __mf_sigusr1_handler);
      handler_installed = 1;
    }
  else if(! __mf_opts.sigusr1_report && handler_installed)
    {
      signal (SIGUSR1, SIG_DFL);
      handler_installed = 0;
    }
#endif

  /* Manage enqueued signals */
  if (__mf_sigusr1_received > __mf_sigusr1_handled)
    {
      __mf_sigusr1_handled ++;
      assert (__mf_state == reentrant);
      __mfu_report ();
      handler_installed = 0; /* We may need to re-enable signal; this might be a SysV library. */
    }
}


/* XXX: provide an alternative __assert_fail function that cannot
   fail due to libmudflap infinite recursion.  */
#ifndef NDEBUG

static void
write_itoa (int fd, unsigned n)
{
  enum x { bufsize = sizeof(n)*4 };
  char buf [bufsize];
  unsigned i;

  for (i=0; i<bufsize-1; i++)
    {
      unsigned digit = n % 10;
      buf[bufsize-2-i] = digit + '0';
      n /= 10;
      if (n == 0) 
	{
	  char *m = & buf [bufsize-2-i];
	  buf[bufsize-1] = '\0';
	  write (fd, m, strlen(m));
	  break;
	}
    }
}


void
__assert_fail (const char *msg, const char *file, unsigned line, const char *func)
{
#define write2(string) write (2, (string), strlen ((string)));
  write2("mf");
#ifdef LIBMUDFLAPTH
  write2("(");
  write_itoa (2, (unsigned) pthread_self ());  
  write2(")");
#endif
  write2(": assertion failure: `");
  write (2, msg, strlen (msg));
  write2("' in ");
  write (2, func, strlen (func));
  write2(" at ");
  write (2, file, strlen (file));
  write2(":");
  write_itoa (2, line);
  write2("\n");
#undef write2
  abort ();
}


#endif