| // boehm.cc - interface between libjava and Boehm GC. |
| |
| /* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 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 <limits.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); |
| p = (ptr_t) c->hack_signers; |
| MAYBE_MARK (p, mark_stack_ptr, mark_stack_limit, c, cSlabel); |
| |
| #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; |
| } |
| |
| // Generate a GC marking descriptor for a class. |
| // |
| // We assume that the gcj mark proc has index 0. This is a dubious assumption, |
| // since another one could be registered first. But the compiler also |
| // knows this, so in that case everything else will break, too. |
| #define GCJ_DEFAULT_DESCR GC_MAKE_PROC(GC_GCJ_RESERVED_MARK_PROC_INDEX,0) |
| |
| void * |
| _Jv_BuildGCDescr(jclass self) |
| { |
| jlong desc = 0; |
| jint bits_per_word = CHAR_BIT * sizeof (void *); |
| |
| // Note: for now we only consider a bitmap mark descriptor. We |
| // could also handle the case where the first N fields of a type are |
| // references. However, this is not very likely to be used by many |
| // classes, and it is easier to compute things this way. |
| |
| // The vtable pointer. |
| desc |= 1ULL << (bits_per_word - 1); |
| #ifndef JV_HASH_SYNCHRONIZATION |
| // The sync_info field. |
| desc |= 1ULL << (bits_per_word - 2); |
| #endif |
| |
| for (jclass klass = self; klass != NULL; klass = klass->getSuperclass()) |
| { |
| jfieldID field = JvGetFirstInstanceField(klass); |
| int count = JvNumInstanceFields(klass); |
| |
| for (int i = 0; i < count; ++i) |
| { |
| if (field->isRef()) |
| { |
| unsigned int off = field->getOffset(); |
| // If we run into a weird situation, we bail. |
| if (off % sizeof (void *) != 0) |
| return (void *) (GCJ_DEFAULT_DESCR); |
| off /= sizeof (void *); |
| // If we find a field outside the range of our bitmap, |
| // fall back to procedure marker. The bottom 2 bits are |
| // reserved. |
| if (off >= bits_per_word - 2) |
| return (void *) (GCJ_DEFAULT_DESCR); |
| desc |= 1ULL << (bits_per_word - off - 1); |
| } |
| |
| field = field->getNextField(); |
| } |
| } |
| |
| // For bitmap mark type, bottom bits are 01. |
| desc |= 1; |
| // Bogus warning avoidance (on many platforms). |
| return (void *) (unsigned long) desc; |
| } |
| |
| // Allocate some space that is known to be pointer-free. |
| void * |
| _Jv_AllocBytes (jsize size) |
| { |
| void *r = GC_MALLOC_ATOMIC (size); |
| // 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. |
| memset (r, 0, size); |
| return r; |
| } |
| |
| // Allocate space for a new Java array. |
| // Used only for arrays of objects. |
| void * |
| _Jv_AllocArray (jsize size, jclass klass) |
| { |
| void *obj; |
| const jsize min_heap_addr = 16*1024; |
| // A heuristic. If size is less than this value, the size |
| // stored in the array can't possibly be misinterpreted as |
| // a pointer. Thus we lose nothing by scanning the object |
| // completely conservatively, since no misidentification can |
| // take place. |
| |
| #ifdef GC_DEBUG |
| // There isn't much to lose by scanning this conservatively. |
| // If we didn't, the mark proc would have to understand that |
| // it needed to skip the header. |
| obj = GC_MALLOC(size); |
| #else |
| if (size < min_heap_addr) |
| obj = GC_MALLOC(size); |
| else |
| obj = GC_generic_malloc (size, array_kind_x); |
| #endif |
| *((_Jv_VTable **) obj) = klass->vtable; |
| return obj; |
| } |
| |
| /* Allocate space for a new non-Java object, which does not have the usual |
| Java object header but may contain pointers to other GC'ed objects. */ |
| void * |
| _Jv_AllocRawObj (jsize size) |
| { |
| return (void *) GC_MALLOC (size); |
| } |
| |
| 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); |
| } |
| |
| static void * handle_out_of_memory(size_t) |
| { |
| _Jv_ThrowNoMemory(); |
| } |
| |
| void |
| _Jv_InitGC (void) |
| { |
| int proc; |
| |
| // Ignore pointers that do not point to the start of an object. |
| GC_all_interior_pointers = 0; |
| |
| // Configure the collector to use the bitmap marking descriptors that we |
| // stash in the class vtable. |
| GC_init_gcj_malloc (0, (void *) _Jv_MarkObj); |
| |
| // Cause an out of memory error to be thrown from the allocators, |
| // instead of returning 0. This is cheaper than checking on allocation. |
| GC_oom_fn = handle_out_of_memory; |
| |
| GC_java_finalization = 1; |
| |
| // We use a different mark procedure for object arrays. This code |
| // configures a different object `kind' for object array allocation and |
| // marking. FIXME: see above. |
| 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] = (GC_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 = GC_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); |
| } |
| |
| #ifdef JV_HASH_SYNCHRONIZATION |
| // Allocate an object with a fake vtable pointer, which causes only |
| // the first field (beyond the fake vtable pointer) to be traced. |
| // Eventually this should probably be generalized. |
| |
| static _Jv_VTable trace_one_vtable = { |
| 0, // class pointer |
| (void *)(2 * sizeof(void *)), |
| // descriptor; scan 2 words incl. vtable ptr. |
| // Least significant bits must be zero to |
| // identify this as a length descriptor |
| {0} // First method |
| }; |
| |
| void * |
| _Jv_AllocTraceOne (jsize size /* includes vtable slot */) |
| { |
| return GC_GCJ_MALLOC (size, &trace_one_vtable); |
| } |
| |
| // Ditto for two words. |
| // the first field (beyond the fake vtable pointer) to be traced. |
| // Eventually this should probably be generalized. |
| |
| static _Jv_VTable trace_two_vtable = |
| { |
| 0, // class pointer |
| (void *)(3 * sizeof(void *)), |
| // descriptor; scan 3 words incl. vtable ptr. |
| {0} // First method |
| }; |
| |
| void * |
| _Jv_AllocTraceTwo (jsize size /* includes vtable slot */) |
| { |
| return GC_GCJ_MALLOC (size, &trace_two_vtable); |
| } |
| |
| #endif /* JV_HASH_SYNCHRONIZATION */ |
| |
| void |
| _Jv_GCInitializeFinalizers (void (*notifier) (void)) |
| { |
| GC_finalize_on_demand = 1; |
| GC_finalizer_notifier = notifier; |
| } |
| |
| void |
| _Jv_GCRegisterDisappearingLink (jobject *objp) |
| { |
| GC_general_register_disappearing_link ((GC_PTR *) objp, (GC_PTR) *objp); |
| } |
| |
| jboolean |
| _Jv_GCCanReclaimSoftReference (jobject) |
| { |
| // For now, always reclaim soft references. FIXME. |
| return true; |
| } |