path: root/libjava/boehm.cc

// boehm.cc - interface between libjava and Boehm GC.

/* Copyright (C) 1998, 1999, 2000  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

#include <config.h>

#include <stdio.h>

#include <jvm.h>
#include <gcj/cni.h>

#include <java/lang/Class.h>
#include <java-interp.h>

// More nastiness: the GC wants to define TRUE and FALSE.  We don't
// need the Java definitions (themselves a hack), so we undefine them.
#undef TRUE
#undef FALSE

extern "C"
{
#include <gc_priv.h>
#include <gc_mark.h>

  // These aren't declared in any Boehm GC header.
  void GC_finalize_all (void);
  ptr_t GC_debug_generic_malloc (size_t size, int k, GC_EXTRA_PARAMS);
};

// FIXME: this should probably be defined in some GC header.
#ifdef GC_DEBUG
#  define GC_GENERIC_MALLOC(Size, Type) \
    GC_debug_generic_malloc (Size, Type, GC_EXTRAS)
#else
#  define GC_GENERIC_MALLOC(Size, Type) GC_generic_malloc (Size, Type)
#endif

// We must check for plausibility ourselves.
#define MAYBE_MARK(Obj, Top, Limit, Source, Exit)  \
      if ((ptr_t) (Obj) >= GC_least_plausible_heap_addr \
	  && (ptr_t) (Obj) <= GC_greatest_plausible_heap_addr) \
        PUSH_CONTENTS (Obj, Top, Limit, Source, Exit)

#define ObjectClass _CL_Q34java4lang6Object
extern java::lang::Class ObjectClass;
#define ClassClass _CL_Q34java4lang5Class
extern java::lang::Class ClassClass;



// Nonzero if this module has been initialized.
static int initialized = 0;

// `kind' index used when allocating Java objects.
static int obj_kind_x;

// `kind' index used when allocating Java arrays.
static int array_kind_x;

// Freelist used for Java objects.
static ptr_t *obj_free_list;

// Freelist used for Java arrays.
static ptr_t *array_free_list;

// Lock used to protect access to Boehm's GC_enable/GC_disable functions.
static _Jv_Mutex_t disable_gc_mutex;



// This is called by the GC during the mark phase.  It marks a Java
// object.  We use `void *' arguments and return, and not what the
// Boehm GC wants, to avoid pollution in our headers.
void *
_Jv_MarkObj (void *addr, void *msp, void *msl, void * /*env*/)
{
  mse *mark_stack_ptr = (mse *) msp;
  mse *mark_stack_limit = (mse *) msl;
  jobject obj = (jobject) addr;

  _Jv_VTable *dt = *(_Jv_VTable **) addr;
  // We check this in case a GC occurs before the vtbl is set.  FIXME:
  // should use allocation lock while initializing object.
  if (! dt)
    return mark_stack_ptr;
  jclass klass = dt->clas;

  // Every object has a sync_info pointer.
  ptr_t p = (ptr_t) obj->sync_info;
  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, obj, o1label);
  // Mark the object's class.
  p = (ptr_t) klass;
  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, obj, o2label);

  if (klass == &ClassClass)
    {
      jclass c = (jclass) addr;

#if 0
      // The next field should probably not be marked, since this is
      // only used in the class hash table.  Marking this field
      // basically prohibits class unloading. --Kresten
      p = (ptr_t) c->next;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c2label);
#endif

      p = (ptr_t) c->name;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c3label);
      p = (ptr_t) c->superclass;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c4label);
      for (int i = 0; i < c->constants.size; ++i)
	{
	  /* FIXME: We could make this more precise by using the tags -KKT */
	  p = (ptr_t) c->constants.data[i].p;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c5label);
	}

#ifdef INTERPRETER
      if (_Jv_IsInterpretedClass (c))
	{
	  p = (ptr_t) c->constants.tags;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c5alabel);
	  p = (ptr_t) c->constants.data;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c5blabel);
	}
#endif

      // If the class is an array, then the methods field holds a
      // pointer to the element class.  If the class is primitive,
      // then the methods field holds a pointer to the array class.
      p = (ptr_t) c->methods;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c6label);


      if (! c->isArray() && ! c->isPrimitive())
	{
	  // Scan each method in the cases where `methods' really
	  // points to a methods structure.
	  for (int i = 0; i < c->method_count; ++i)
	    {
	      p = (ptr_t) c->methods[i].name;
	      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c,
			     cm1label);
	      p = (ptr_t) c->methods[i].signature;
	      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c,
			     cm2label);

	      // FIXME: `ncode' entry?

#ifdef INTERPRETER
	      // The interpreter installs a heap-allocated
	      // trampoline here, so we'll mark it. 
	      if (_Jv_IsInterpretedClass (c))
		  {
		      p = (ptr_t) c->methods[i].ncode;
		      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c,
				  cm3label);
		  }
#endif
	    }
	}

      // Mark all the fields.
      p = (ptr_t) c->fields;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c8label);
      for (int i = 0; i < c->field_count; ++i)
	{
	  _Jv_Field* field = &c->fields[i];

#ifndef COMPACT_FIELDS
	  p = (ptr_t) field->name;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c8alabel);
#endif
	  p = (ptr_t) field->type;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c8blabel);

	  // For the interpreter, we also need to mark the memory
	  // containing static members
	  if (field->flags & 0x0008)
	    {
	      p = (ptr_t) field->u.addr;
	      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c8clabel);

	      // also, if the static member is a reference,
	      // mark also the value pointed to.  We check for isResolved
	      // since marking can happen before memory is allocated for
	      // static members.
	      if (JvFieldIsRef (field) && field->isResolved()) 
		{
		  jobject val = *(jobject*) field->u.addr;
		  p = (ptr_t) val;
		  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit,
			      c, c8elabel);
		}
	    }
	}

      p = (ptr_t) c->vtable;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c9label);
      p = (ptr_t) c->interfaces;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, cAlabel);
      for (int i = 0; i < c->interface_count; ++i)
	{
	  p = (ptr_t) c->interfaces[i];
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, cClabel);
	}
      p = (ptr_t) c->loader;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, cBlabel);

#ifdef INTERPRETER
      if (_Jv_IsInterpretedClass (c))
	{
	  _Jv_InterpClass* ic = (_Jv_InterpClass*)c;

	  p = (ptr_t) ic->interpreted_methods;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, ic, cElabel);

	  for (int i = 0; i < c->method_count; i++)
	    {
	      p = (ptr_t) ic->interpreted_methods[i];
	      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, ic, \
			  cFlabel);
	    }

	  p = (ptr_t) ic->field_initializers;
	  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, ic, cGlabel);
	  
	}
#endif

    }
  else
    {
      // NOTE: each class only holds information about the class
      // itself.  So we must do the marking for the entire inheritance
      // tree in order to mark all fields.  FIXME: what about
      // interfaces?  We skip Object here, because Object only has a
      // sync_info, and we handled that earlier.
      // Note: occasionally `klass' can be null.  For instance, this
      // can happen if a GC occurs between the point where an object
      // is allocated and where the vtbl slot is set.
      while (klass && klass != &ObjectClass)
	{
	  jfieldID field = JvGetFirstInstanceField (klass);
	  jint max = JvNumInstanceFields (klass);

	  for (int i = 0; i < max; ++i)
	    {
	      if (JvFieldIsRef (field))
		{
		  jobject val = JvGetObjectField (obj, field);
		  p = (ptr_t) val;
		  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit,
			      obj, elabel);
		}
	      field = field->getNextField ();
	    }
	  klass = klass->getSuperclass();
	}
    }

  return mark_stack_ptr;
}

// This is called by the GC during the mark phase.  It marks a Java
// array (of objects).  We use `void *' arguments and return, and not
// what the Boehm GC wants, to avoid pollution in our headers.
void *
_Jv_MarkArray (void *addr, void *msp, void *msl, void * /*env*/)
{
  mse *mark_stack_ptr = (mse *) msp;
  mse *mark_stack_limit = (mse *) msl;
  jobjectArray array = (jobjectArray) addr;

  _Jv_VTable *dt = *(_Jv_VTable **) addr;
  // We check this in case a GC occurs before the vtbl is set.  FIXME:
  // should use allocation lock while initializing object.
  if (! dt)
    return mark_stack_ptr;
  jclass klass = dt->clas;

  // Every object has a sync_info pointer.
  ptr_t p = (ptr_t) array->sync_info;
  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, array, e1label);
  // Mark the object's class.
  p = (ptr_t) klass;
  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, obj, o2label);

  for (int i = 0; i < JvGetArrayLength (array); ++i)
    {
      jobject obj = elements (array)[i];
      p = (ptr_t) obj;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, array, e2label);
    }

  return mark_stack_ptr;
}

// Allocate space for a new Java object.  FIXME: this might be the
// wrong interface; we might prefer to pass in the object type as
// well.  It isn't important for this collector, but it might be for
// other collectors.
void *
_Jv_AllocObj (jsize size)
{
  return GC_GENERIC_MALLOC (size, obj_kind_x);
}

// Allocate space for a new Java array.  FIXME: again, this might be
// the wrong interface.
void *
_Jv_AllocArray (jsize size)
{
  return GC_GENERIC_MALLOC (size, array_kind_x);
}

// Allocate some space that is known to be pointer-free.
void *
_Jv_AllocBytes (jsize size)
{
  void *r = GC_GENERIC_MALLOC (size, PTRFREE);
  // We have to explicitly zero memory here, as the GC doesn't
  // guarantee that PTRFREE allocations are zeroed.  Note that we
  // don't have to do this for other allocation types because we set
  // the `ok_init' flag in the type descriptor.
  if (r != NULL)
    memset (r, 0, size);
  return r;
}

static void
call_finalizer (GC_PTR obj, GC_PTR client_data)
{
  _Jv_FinalizerFunc *fn = (_Jv_FinalizerFunc *) client_data;
  jobject jobj = (jobject) obj;

  (*fn) (jobj);
}

void
_Jv_RegisterFinalizer (void *object, _Jv_FinalizerFunc *meth)
{
  GC_REGISTER_FINALIZER_NO_ORDER (object, call_finalizer, (GC_PTR) meth,
				  NULL, NULL);
}

void
_Jv_RunFinalizers (void)
{
  GC_invoke_finalizers ();
}

void
_Jv_RunAllFinalizers (void)
{
  GC_finalize_all ();
}

void
_Jv_RunGC (void)
{
  GC_gcollect ();
}

long
_Jv_GCTotalMemory (void)
{
  return GC_get_heap_size ();
}

long
_Jv_GCFreeMemory (void)
{
  return GC_get_free_bytes ();
}

void
_Jv_GCSetInitialHeapSize (size_t size)
{
  size_t current = GC_get_heap_size ();
  if (size > current)
    GC_expand_hp (size - current);
}

void
_Jv_GCSetMaximumHeapSize (size_t size)
{
  GC_set_max_heap_size ((GC_word) size);
}

// From boehm's misc.c 
extern "C" void GC_enable();
extern "C" void GC_disable();

void
_Jv_DisableGC (void)
{
  _Jv_MutexLock (&disable_gc_mutex); 
  GC_disable();
  _Jv_MutexUnlock (&disable_gc_mutex); 
}

void
_Jv_EnableGC (void)
{
  _Jv_MutexLock (&disable_gc_mutex); 
  GC_enable();
  _Jv_MutexUnlock (&disable_gc_mutex); 
}

void
_Jv_InitGC (void)
{
  int proc;
  DCL_LOCK_STATE;

  DISABLE_SIGNALS ();
  LOCK ();

  if (initialized)
    {
      UNLOCK ();
      ENABLE_SIGNALS ();
      return;
    }
  initialized = 1;

  GC_java_finalization = 1;

  // Set up state for marking and allocation of Java objects.
  obj_free_list = (ptr_t *) GC_generic_malloc_inner ((MAXOBJSZ + 1)
						     * sizeof (ptr_t),
						     PTRFREE);
  memset (obj_free_list, 0, (MAXOBJSZ + 1) * sizeof (ptr_t));

  proc = GC_n_mark_procs++;
  GC_mark_procs[proc] = (mark_proc) _Jv_MarkObj;

  obj_kind_x = GC_n_kinds++;
  GC_obj_kinds[obj_kind_x].ok_freelist = obj_free_list;
  GC_obj_kinds[obj_kind_x].ok_reclaim_list = 0;
  GC_obj_kinds[obj_kind_x].ok_descriptor = MAKE_PROC (proc, 0);
  GC_obj_kinds[obj_kind_x].ok_relocate_descr = FALSE;
  GC_obj_kinds[obj_kind_x].ok_init = TRUE;

  // Set up state for marking and allocation of arrays of Java
  // objects.
  array_free_list = (ptr_t *) GC_generic_malloc_inner ((MAXOBJSZ + 1)
						       * sizeof (ptr_t),
						       PTRFREE);
  memset (array_free_list, 0, (MAXOBJSZ + 1) * sizeof (ptr_t));

  proc = GC_n_mark_procs++;
  GC_mark_procs[proc] = (mark_proc) _Jv_MarkArray;

  array_kind_x = GC_n_kinds++;
  GC_obj_kinds[array_kind_x].ok_freelist = array_free_list;
  GC_obj_kinds[array_kind_x].ok_reclaim_list = 0;
  GC_obj_kinds[array_kind_x].ok_descriptor = MAKE_PROC (proc, 0);
  GC_obj_kinds[array_kind_x].ok_relocate_descr = FALSE;
  GC_obj_kinds[array_kind_x].ok_init = TRUE;

  _Jv_MutexInit (&disable_gc_mutex);

  UNLOCK ();
  ENABLE_SIGNALS ();
}