3 // Size sans alignment.
4 template <typename Fixup>
5 cell object::base_size(Fixup fixup) const {
8 return array_size((array*)this);
10 return array_size((bignum*)this);
12 return array_size((byte_array*)this);
14 return string_size(string_capacity((string*)this));
16 tuple_layout* layout = (tuple_layout*)fixup.translate_data(
17 untag<object>(((tuple*)this)->layout));
18 return tuple_size(layout);
21 return sizeof(quotation);
25 return sizeof(boxed_float);
31 return sizeof(wrapper);
32 case CALLSTACK_TYPE: {
33 cell callstack_length = untag_fixnum(((callstack*)this)->length);
34 return callstack_object_size(callstack_length);
37 critical_error("Invalid header in base_size", (cell)this);
42 // Size of the object pointed to by an untagged pointer
43 template <typename Fixup>
44 cell object::size(Fixup fixup) const {
46 return ((free_heap_block*)this)->size();
47 return align(base_size(fixup), data_alignment);
50 inline cell object::size() const { return size(no_fixup()); }
52 // The number of slots (cells) in an object which should be scanned by
53 // the GC. The number can vary in arrays and tuples, in all other
54 // types the number is a constant.
55 template <typename Fixup>
56 inline cell object::slot_count(Fixup fixup) const {
61 if (t == ARRAY_TYPE) {
63 return 1 + array_capacity((array*)this);
64 } else if (t == TUPLE_TYPE) {
65 tuple_layout* layout = (tuple_layout*)fixup.translate_data(
66 untag<object>(((tuple*)this)->layout));
68 return 1 + tuple_capacity(layout);
71 // these objects do not refer to other objects at all
75 case CALLSTACK_TYPE: return 0;
76 case WORD_TYPE: return 8;
77 case ALIEN_TYPE: return 2;
78 case DLL_TYPE: return 1;
79 case QUOTATION_TYPE: return 3;
80 case STRING_TYPE: return 3;
81 case WRAPPER_TYPE: return 1;
83 critical_error("Invalid header in slot_count", (cell)this);
84 return 0; // can't happen
89 inline cell object::slot_count() const {
90 return slot_count(no_fixup());
93 // Slot visitors iterate over the slots of an object, applying a functor to
94 // each one that is a non-immediate slot. The pointer is untagged first.
95 // The functor returns a new untagged object pointer. The return value may
96 // or may not equal the old one, however the new pointer receives the same
97 // tag before being stored back to the original location.
99 // Slots storing immediate values are left unchanged and the visitor does
102 // This is used by GC's copying, sweep and compact phases, and the
103 // implementation of the become primitive.
105 // Iteration is driven by visit_*() methods. Only one of them define GC
107 // - visit_all_roots()
109 // Code block visitors iterate over sets of code blocks, applying a functor
110 // to each one. The functor returns a new code_block pointer, which may or
111 // may not equal the old one. This is stored back to the original location.
113 // This is used by GC's sweep and compact phases, and the implementation of
114 // the modify-code-heap primitive.
116 // Iteration is driven by visit_*() methods. Some of them define GC roots:
117 // - visit_context_code_blocks()
118 // - visit_callback_code_blocks()
120 template <typename Fixup> struct slot_visitor {
126 slot_visitor<Fixup>(factor_vm* parent, Fixup fixup)
132 cell visit_pointer(cell pointer);
133 void visit_handle(cell* handle);
134 void visit_object_array(cell* start, cell* end);
135 void visit_partial_objects(cell start, cell card_start, cell card_end);
136 void visit_slots(object* ptr);
137 void visit_stack_elements(segment* region, cell* top);
138 void visit_all_roots();
139 void visit_callstack_object(callstack* stack);
140 void visit_callstack(context* ctx);
141 void visit_context(context *ctx);
142 void visit_object_code_block(object* obj);
143 void visit_context_code_blocks();
144 void visit_uninitialized_code_blocks();
145 void visit_object(object* obj);
146 void visit_mark_stack(std::vector<cell>* mark_stack);
149 template <typename SourceGeneration>
150 cell visit_card(SourceGeneration* gen, cell index, cell start);
151 template <typename SourceGeneration>
152 void visit_cards(SourceGeneration* gen, card mask, card unmask);
155 template <typename TargetGeneration>
156 void cheneys_algorithm(TargetGeneration* gen, cell scan);
158 // Visits the data pointers in code blocks in the remembered set.
159 void visit_code_heap_roots(std::set<code_block*>* remembered_set);
161 // Visits pointers embedded in instructions in code blocks.
162 void visit_instruction_operands(code_block* block, cell rel_base);
163 void visit_embedded_code_pointers(code_block* compiled);
164 void visit_embedded_literals(code_block* compiled);
166 // Visits data pointers in code blocks.
167 void visit_code_block_objects(code_block* compiled);
170 template <typename Fixup>
171 cell slot_visitor<Fixup>::visit_pointer(cell pointer) {
172 object* untagged = fixup.fixup_data(untag<object>(pointer));
173 return RETAG(untagged, TAG(pointer));
176 template <typename Fixup> void slot_visitor<Fixup>::visit_handle(cell* handle) {
177 if (!immediate_p(*handle)) {
178 *handle = visit_pointer(*handle);
182 template <typename Fixup>
183 void slot_visitor<Fixup>::visit_object_array(cell* start, cell* end) {
185 visit_handle(start++);
188 template <typename Fixup> void slot_visitor<Fixup>::visit_slots(object* obj) {
189 if (obj->type() == CALLSTACK_TYPE)
190 visit_callstack_object((callstack*)obj);
192 cell* start = (cell*)obj + 1;
193 cell* end = start + obj->slot_count(fixup);
194 visit_object_array(start, end);
198 template <typename Fixup>
199 void slot_visitor<Fixup>::visit_stack_elements(segment* region, cell* top) {
200 visit_object_array((cell*)region->start, top + 1);
203 template <typename Fixup> void slot_visitor<Fixup>::visit_all_roots() {
204 FACTOR_FOR_EACH(parent->data_roots) {
208 auto callback_slot_visitor = [&](code_block* stub, cell size) {
210 visit_handle(&stub->owner);
212 parent->callbacks->allocator->iterate(callback_slot_visitor, no_fixup());
214 FACTOR_FOR_EACH(parent->code->uninitialized_blocks) {
215 iter->second = visit_pointer(iter->second);
218 FACTOR_FOR_EACH(parent->samples) {
219 visit_handle(&iter->thread);
222 visit_object_array(parent->special_objects,
223 parent->special_objects + special_object_count);
225 FACTOR_FOR_EACH(parent->active_contexts) {
226 visit_context(*iter);
230 // primitive_minor_gc() is invoked by inline GC checks, and it needs to
231 // visit spill slots which references objects in the heap.
233 // So for each call frame:
234 // - trace roots in spill slots
236 template <typename Fixup> struct call_frame_slot_visitor {
237 slot_visitor<Fixup>* visitor;
239 call_frame_slot_visitor(slot_visitor<Fixup>* visitor)
240 : visitor(visitor) {}
242 // frame top -> [return address]
248 void operator()(cell frame_top, cell size, code_block* owner, cell addr) {
250 cell return_address = owner->offset(addr);
252 code_block* compiled =
253 Fixup::translated_code_block_map ? owner
254 : visitor->fixup.translate_code(owner);
255 gc_info* info = compiled->block_gc_info();
257 FACTOR_ASSERT(return_address < compiled->size());
258 cell callsite = info->return_address_index(return_address);
259 if (callsite == (cell)-1)
263 FACTOR_PRINT("call frame code block " << compiled << " with offset "
266 cell* stack_pointer = (cell*)frame_top;
267 uint8_t* bitmap = info->gc_info_bitmap();
269 // Subtract old value of base pointer from every derived pointer.
270 for (cell spill_slot = 0; spill_slot < info->derived_root_count;
272 uint32_t base_pointer = info->lookup_base_pointer(callsite, spill_slot);
273 if (base_pointer != (uint32_t)-1) {
275 FACTOR_PRINT("visiting derived root " << spill_slot
276 << " with base pointer " << base_pointer);
278 stack_pointer[spill_slot] -= stack_pointer[base_pointer];
282 // Update all GC roots, including base pointers.
283 cell callsite_gc_roots = info->callsite_gc_roots(callsite);
285 for (cell spill_slot = 0; spill_slot < info->gc_root_count; spill_slot++) {
286 if (bitmap_p(bitmap, callsite_gc_roots + spill_slot)) {
288 FACTOR_PRINT("visiting GC root " << spill_slot);
290 visitor->visit_handle(stack_pointer + spill_slot);
294 // Add the base pointers to obtain new derived pointer values.
295 for (cell spill_slot = 0; spill_slot < info->derived_root_count;
297 uint32_t base_pointer = info->lookup_base_pointer(callsite, spill_slot);
298 if (base_pointer != (uint32_t)-1)
299 stack_pointer[spill_slot] += stack_pointer[base_pointer];
304 template <typename Fixup>
305 void slot_visitor<Fixup>::visit_callstack_object(callstack* stack) {
306 call_frame_slot_visitor<Fixup> call_frame_visitor(this);
307 parent->iterate_callstack_object(stack, call_frame_visitor, fixup);
310 template <typename Fixup>
311 void slot_visitor<Fixup>::visit_callstack(context* ctx) {
312 call_frame_slot_visitor<Fixup> call_frame_visitor(this);
313 parent->iterate_callstack(ctx, call_frame_visitor, fixup);
316 template <typename Fixup>
317 void slot_visitor<Fixup>::visit_context(context* ctx) {
318 visit_callstack(ctx);
320 cell ds_ptr = ctx->datastack;
321 cell rs_ptr = ctx->retainstack;
322 segment* ds_seg = ctx->datastack_seg;
323 segment* rs_seg = ctx->retainstack_seg;
324 visit_stack_elements(ds_seg, (cell*)ds_ptr);
325 visit_stack_elements(rs_seg, (cell*)rs_ptr);
326 visit_object_array(ctx->context_objects,
327 ctx->context_objects + context_object_count);
329 // Clear out the space not visited with a known pattern. That makes
330 // it easier to see if uninitialized reads are made.
331 ctx->fill_stack_seg(ds_ptr, ds_seg, 0xbaadbadd);
332 ctx->fill_stack_seg(rs_ptr, rs_seg, 0xdaabdabb);
335 template <typename Fixup>
336 void slot_visitor<Fixup>::visit_code_block_objects(code_block* compiled) {
337 visit_handle(&compiled->owner);
338 visit_handle(&compiled->parameters);
339 visit_handle(&compiled->relocation);
342 template <typename Fixup>
343 void slot_visitor<Fixup>::visit_embedded_literals(code_block* compiled) {
344 if (parent->code->uninitialized_p(compiled))
347 auto update_literal_refs = [&](instruction_operand op) {
348 if (op.rel.type() == RT_LITERAL) {
349 cell value = op.load_value(op.pointer);
350 if (!immediate_p(value)) {
351 op.store_value(visit_pointer(value));
355 compiled->each_instruction_operand(update_literal_refs);
358 template <typename Fixup> struct call_frame_code_block_visitor {
361 call_frame_code_block_visitor(Fixup fixup) : fixup(fixup) {}
363 void operator()(cell frame_top, cell size, code_block* owner, cell addr) {
365 code_block* compiled =
366 Fixup::translated_code_block_map ? owner : fixup.fixup_code(owner);
367 cell fixed_addr = compiled->address_for_offset(owner->offset(addr));
369 *(cell*)frame_top = fixed_addr;
373 template <typename Fixup>
374 void slot_visitor<Fixup>::visit_object_code_block(object* obj) {
375 switch (obj->type()) {
377 word* w = (word*)obj;
379 w->entry_point = fixup.fixup_code(w->code())->entry_point();
382 case QUOTATION_TYPE: {
383 quotation* q = (quotation*)obj;
385 q->entry_point = fixup.fixup_code(q->code())->entry_point();
388 case CALLSTACK_TYPE: {
389 callstack* stack = (callstack*)obj;
390 call_frame_code_block_visitor<Fixup> call_frame_visitor(fixup);
391 parent->iterate_callstack_object(stack, call_frame_visitor, fixup);
397 template <typename Fixup>
398 void slot_visitor<Fixup>::visit_context_code_blocks() {
399 call_frame_code_block_visitor<Fixup> call_frame_visitor(fixup);
400 FACTOR_FOR_EACH(parent->active_contexts) {
401 parent->iterate_callstack(*iter, call_frame_visitor, fixup);
405 template <typename Fixup>
406 void slot_visitor<Fixup>::visit_uninitialized_code_blocks() {
407 std::map<code_block*, cell> new_uninitialized_blocks;
408 FACTOR_FOR_EACH(parent->code->uninitialized_blocks) {
409 new_uninitialized_blocks.insert(
410 std::make_pair(fixup.fixup_code(iter->first), iter->second));
412 parent->code->uninitialized_blocks = new_uninitialized_blocks;
415 template <typename Fixup>
416 void slot_visitor<Fixup>::visit_embedded_code_pointers(code_block* compiled) {
417 if (parent->code->uninitialized_p(compiled))
419 auto update_code_block_refs = [&](instruction_operand op){
420 relocation_type type = op.rel.type();
421 if (type == RT_ENTRY_POINT ||
422 type == RT_ENTRY_POINT_PIC ||
423 type == RT_ENTRY_POINT_PIC_TAIL) {
424 code_block* block = fixup.fixup_code(op.load_code_block());
425 op.store_value(block->entry_point());
428 compiled->each_instruction_operand(update_code_block_refs);
431 template <typename Fixup>
432 void slot_visitor<Fixup>::visit_object(object *ptr) {
434 if (ptr->type() == ALIEN_TYPE)
435 ((alien*)ptr)->update_address();
438 // Pops items from the mark stack and visits them until the stack is
439 // empty. Used when doing a full collection and when collecting to
441 template <typename Fixup>
442 void slot_visitor<Fixup>::visit_mark_stack(std::vector<cell>* mark_stack) {
443 while (!mark_stack->empty()) {
444 cell ptr = mark_stack->back();
445 mark_stack->pop_back();
448 code_block* compiled = (code_block*)(ptr - 1);
449 visit_code_block_objects(compiled);
450 visit_embedded_literals(compiled);
451 visit_embedded_code_pointers(compiled);
453 object* obj = (object*)ptr;
455 visit_object_code_block(obj);
460 // Visits the instruction operands in a code block. If the operand is
461 // a pointer to a code block or data object, then the fixup is applied
462 // to it. Otherwise, if it is an external addess, that address is
463 // recomputed. If it is an untagged number literal (RT_UNTAGGED) or an
464 // immediate value, then nothing is done with it.
465 template <typename Fixup>
466 void slot_visitor<Fixup>::visit_instruction_operands(code_block* block,
468 auto visit_func = [&](instruction_operand op){
469 cell old_offset = rel_base + op.rel.offset();
470 cell old_value = op.load_value(old_offset);
471 switch (op.rel.type()) {
473 if (!immediate_p(old_value)) {
474 op.store_value(visit_pointer(old_value));
479 case RT_ENTRY_POINT_PIC:
480 case RT_ENTRY_POINT_PIC_TAIL:
482 cell offset = TAG(old_value);
483 code_block* compiled = (code_block*)UNTAG(old_value);
484 op.store_value(RETAG(fixup.fixup_code(compiled), offset));
490 op.store_value(parent->compute_external_address(op));
494 if (parent->code->uninitialized_p(block))
496 block->each_instruction_operand(visit_func);
499 template <typename Fixup>
500 void slot_visitor<Fixup>::visit_partial_objects(cell start,
503 cell *scan_start = (cell*)start + 1;
504 cell *scan_end = scan_start + ((object*)start)->slot_count();
506 scan_start = std::max(scan_start, (cell*)card_start);
507 scan_end = std::min(scan_end, (cell*)card_end);
509 visit_object_array(scan_start, scan_end);
512 template <typename Fixup>
513 template <typename SourceGeneration>
514 cell slot_visitor<Fixup>::visit_card(SourceGeneration* gen,
515 cell index, cell start) {
516 cell heap_base = parent->data->start;
517 cell start_addr = heap_base + index * card_size;
518 cell end_addr = start_addr + card_size;
520 // Forward to the next object whose address is in the card.
521 if (!start || (start + ((object*)start)->size()) < start_addr) {
522 // Optimization because finding the objects in a memory range is
523 // expensive. It helps a lot when tracing consecutive cards.
524 cell gen_start_card = (gen->start - heap_base) / card_size;
526 .find_object_containing_card(index - gen_start_card);
529 while (start && start < end_addr) {
530 visit_partial_objects(start, start_addr, end_addr);
531 if ((start + ((object*)start)->size()) >= end_addr) {
532 // The object can overlap the card boundary, then the
533 // remainder of it will be handled in the next card
534 // tracing if that card is marked.
537 start = gen->next_object_after(start);
542 template <typename Fixup>
543 template <typename SourceGeneration>
544 void slot_visitor<Fixup>::visit_cards(SourceGeneration* gen,
545 card mask, card unmask) {
546 card_deck* decks = parent->data->decks;
547 card_deck* cards = parent->data->cards;
548 cell heap_base = parent->data->start;
550 cell first_deck = (gen->start - heap_base) / deck_size;
551 cell last_deck = (gen->end - heap_base) / deck_size;
553 // Address of last traced object.
555 for (cell di = first_deck; di < last_deck; di++) {
556 if (decks[di] & mask) {
557 decks[di] &= ~unmask;
560 cell first_card = cards_per_deck * di;
561 cell last_card = first_card + cards_per_deck;
563 for (cell ci = first_card; ci < last_card; ci++) {
564 if (cards[ci] & mask) {
565 cards[ci] &= ~unmask;
568 start = visit_card(gen, ci, start);
570 // At end of generation, no need to scan more cards.
579 template <typename Fixup>
580 void slot_visitor<Fixup>::visit_code_heap_roots(std::set<code_block*>* remembered_set) {
581 FACTOR_FOR_EACH(*remembered_set) {
582 code_block* compiled = *iter;
583 visit_code_block_objects(compiled);
584 visit_embedded_literals(compiled);
585 compiled->flush_icache();
589 template <typename Fixup>
590 template <typename TargetGeneration>
591 void slot_visitor<Fixup>::cheneys_algorithm(TargetGeneration* gen, cell scan) {
592 while (scan && scan < gen->here) {
593 visit_object((object*)scan);
594 scan = gen->next_object_after(scan);