source: trunk/src/gcc/libjava/boehm.cc@ 1519

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

/* Copyright (C) 1998, 1999, 2000, 2001, 2002  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/lang/reflect/Modifier.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 <private/gc_pmark.h>
#include <gc_gcj.h>

#ifdef THREAD_LOCAL_ALLOC
# define GC_REDIRECT_TO_LOCAL
# include <gc_local_alloc.h>
#endif

  // 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);
};

#define MAYBE_MARK(Obj, Top, Limit, Source, Exit)  \
        Top=GC_MARK_AND_PUSH((GC_PTR)Obj, Top, Limit, (GC_PTR *)Source)

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

// 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;

  // FIXME: if env is 1, this object was allocated through the debug
  // interface, and addr points to the beginning of the debug header.
  // In that case, we should really add the size of the header to addr.

  _Jv_VTable *dt = *(_Jv_VTable **) addr;
  // The object might not yet have its vtable set, or it might
  // really be an object on the freelist.  In either case, the vtable slot
  // will either be 0, or it will point to a cleared object.
  // This assumes Java objects have size at least 3 words,
  // including the header.   But this should remain true, since this
  // should only be used with debugging allocation or with large objects.
  if (__builtin_expect (! dt || !(dt -> get_finalizer()), false))
    return mark_stack_ptr;
  jclass klass = dt->clas;
  ptr_t p;

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

  if (__builtin_expect (klass == &java::lang::Class::class$, false))
    {
      // Currently we allocate some of the memory referenced from class objects
      // as pointerfree memory, and then mark it more intelligently here.
      // We ensure that the ClassClass mark descriptor forces invocation of
      // this procedure.
      // Correctness of this is subtle, but it looks OK to me for now.  For the incremental
      // collector, we need to make sure that the class object is written whenever
      // any of the subobjects are altered and may need rescanning.  This may be tricky
      // during construction, and this may not be the right way to do this with
      // incremental collection.
      // If we overflow the mark stack, we will rescan the class object, so we should
      // be OK.  The same applies if we redo the mark phase because win32 unmapped part
      // of our root set.               - HB
      jclass c = (jclass) addr;

      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);
          p = (ptr_t) c->vtable;
          MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, c5clabel);
        }
#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);

      // The vtable might have been set, but the rest of the class
      // could still be uninitialized.  If this is the case, then
      // c.isArray will SEGV.  We check for this, and if it is the
      // case we just return.
      if (__builtin_expect (c->name == NULL, false))
        return mark_stack_ptr;

      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);
            }
        }

      // 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 & java::lang::reflect::Modifier::STATIC))
            {
              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);
      p = (ptr_t) c->arrayclass;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, cDlabel);
      p = (ptr_t) c->protectionDomain;
      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, cPlabel);

#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);

              // Mark the direct-threaded code.
              if ((c->methods[i].accflags
                   & java::lang::reflect::Modifier::NATIVE) == 0)
                {
                  _Jv_InterpMethod *im
                    = (_Jv_InterpMethod *) ic->interpreted_methods[i];
                  if (im)
                    {
                      p = (ptr_t) im->prepared;
                      MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, ic, \
                                  cFlabel);
                    }
                }

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

          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 != &java::lang::Object::class$)
        {
          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;
  // Assumes size >= 3 words.  That's currently true since arrays have
  // a vtable, sync pointer, and size.  If the sync pointer goes away,
  // we may need to round up the size.
  if (__builtin_expect (! dt || !(dt -> get_finalizer()), false))
    return mark_stack_ptr;
  jclass klass = dt->clas;
  ptr_t p;

# ifndef JV_HASH_SYNCHRONIZATION
    // Every object has a sync_info pointer.
    p = (ptr_t) array->sync_info;
    MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, array, e1label);
# endif
  // Mark the object's class.
  p = (ptr_t) klass;
  MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, &(dt -> clas), 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;