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_code_block_objects(code_block* compiled);
143 void visit_embedded_literals(code_block* compiled);
144 void visit_object_code_block(object* obj);
145 void visit_context_code_blocks();
146 void visit_uninitialized_code_blocks();
147 void visit_embedded_code_pointers(code_block* compiled);
148 void visit_object(object* obj);
149 void visit_mark_stack(std::vector<cell>* mark_stack);
150 void visit_instruction_operands(code_block* block, cell rel_base);
152 template <typename SourceGeneration>
153 cell visit_card(SourceGeneration* gen, cell index, cell start);
154 template <typename SourceGeneration>
155 void visit_cards(SourceGeneration* gen, card mask, card unmask);
156 void visit_code_heap_roots(std::set<code_block*>* remembered_set);
158 template <typename TargetGeneration>
159 void cheneys_algorithm(TargetGeneration* gen, cell scan);
162 template <typename Fixup>
163 cell slot_visitor<Fixup>::visit_pointer(cell pointer) {
164 object* untagged = fixup.fixup_data(untag<object>(pointer));
165 return RETAG(untagged, TAG(pointer));
168 template <typename Fixup> void slot_visitor<Fixup>::visit_handle(cell* handle) {
169 if (!immediate_p(*handle)) {
170 *handle = visit_pointer(*handle);
174 template <typename Fixup>
175 void slot_visitor<Fixup>::visit_object_array(cell* start, cell* end) {
177 visit_handle(start++);
180 template <typename Fixup> void slot_visitor<Fixup>::visit_slots(object* obj) {
181 if (obj->type() == CALLSTACK_TYPE)
182 visit_callstack_object((callstack*)obj);
184 cell* start = (cell*)obj + 1;
185 cell* end = start + obj->slot_count(fixup);
186 visit_object_array(start, end);
190 template <typename Fixup>
191 void slot_visitor<Fixup>::visit_stack_elements(segment* region, cell* top) {
192 visit_object_array((cell*)region->start, top + 1);
195 template <typename Fixup> void slot_visitor<Fixup>::visit_all_roots() {
196 FACTOR_FOR_EACH(parent->data_roots) {
200 auto callback_slot_visitor = [&](code_block* stub, cell size) {
201 visit_handle(&stub->owner);
203 parent->callbacks->allocator->iterate(callback_slot_visitor);
205 FACTOR_FOR_EACH(parent->code->uninitialized_blocks) {
206 iter->second = visit_pointer(iter->second);
209 FACTOR_FOR_EACH(parent->sample_callstacks) {
210 visit_handle(&*iter);
213 FACTOR_FOR_EACH(parent->samples) {
214 visit_handle(&iter->thread);
217 visit_object_array(parent->special_objects,
218 parent->special_objects + special_object_count);
220 FACTOR_FOR_EACH(parent->active_contexts) {
221 visit_context(*iter);
225 // primitive_minor_gc() is invoked by inline GC checks, and it needs to
226 // visit spill slots which references objects in the heap.
228 // So for each call frame:
229 // - trace roots in spill slots
231 template <typename Fixup> struct call_frame_slot_visitor {
232 slot_visitor<Fixup>* visitor;
234 call_frame_slot_visitor(slot_visitor<Fixup>* visitor)
235 : visitor(visitor) {}
237 // frame top -> [return address]
243 void operator()(cell frame_top, cell size, code_block* owner, cell addr) {
244 cell return_address = owner->offset(addr);
246 code_block* compiled =
247 Fixup::translated_code_block_map ? owner
248 : visitor->fixup.translate_code(owner);
249 gc_info* info = compiled->block_gc_info();
251 FACTOR_ASSERT(return_address < compiled->size());
252 cell callsite = info->return_address_index(return_address);
253 if (callsite == (cell)-1)
257 FACTOR_PRINT("call frame code block " << compiled << " with offset "
260 cell* stack_pointer = (cell*)frame_top;
261 uint8_t* bitmap = info->gc_info_bitmap();
263 // Subtract old value of base pointer from every derived pointer.
264 for (cell spill_slot = 0; spill_slot < info->derived_root_count;
266 uint32_t base_pointer = info->lookup_base_pointer(callsite, spill_slot);
267 if (base_pointer != (uint32_t)-1) {
269 FACTOR_PRINT("visiting derived root " << spill_slot
270 << " with base pointer " << base_pointer);
272 stack_pointer[spill_slot] -= stack_pointer[base_pointer];
276 // Update all GC roots, including base pointers.
277 cell callsite_gc_roots = info->callsite_gc_roots(callsite);
279 for (cell spill_slot = 0; spill_slot < info->gc_root_count; spill_slot++) {
280 if (bitmap_p(bitmap, callsite_gc_roots + spill_slot)) {
282 FACTOR_PRINT("visiting GC root " << spill_slot);
284 visitor->visit_handle(stack_pointer + spill_slot);
288 // Add the base pointers to obtain new derived pointer values.
289 for (cell spill_slot = 0; spill_slot < info->derived_root_count;
291 uint32_t base_pointer = info->lookup_base_pointer(callsite, spill_slot);
292 if (base_pointer != (uint32_t)-1)
293 stack_pointer[spill_slot] += stack_pointer[base_pointer];
298 template <typename Fixup>
299 void slot_visitor<Fixup>::visit_callstack_object(callstack* stack) {
300 call_frame_slot_visitor<Fixup> call_frame_visitor(this);
301 parent->iterate_callstack_object(stack, call_frame_visitor, fixup);
304 template <typename Fixup>
305 void slot_visitor<Fixup>::visit_callstack(context* ctx) {
306 call_frame_slot_visitor<Fixup> call_frame_visitor(this);
307 parent->iterate_callstack(ctx, call_frame_visitor, fixup);
310 template <typename Fixup>
311 void slot_visitor<Fixup>::visit_context(context* ctx) {
312 // Callstack is visited first because it scrubs the data and retain
314 visit_callstack(ctx);
316 cell ds_ptr = ctx->datastack;
317 cell rs_ptr = ctx->retainstack;
318 segment* ds_seg = ctx->datastack_seg;
319 segment* rs_seg = ctx->retainstack_seg;
320 visit_stack_elements(ds_seg, (cell*)ds_ptr);
321 visit_stack_elements(rs_seg, (cell*)rs_ptr);
322 visit_object_array(ctx->context_objects,
323 ctx->context_objects + context_object_count);
325 // Clear out the space not visited with a known pattern. That makes
326 // it easier to see if uninitialized reads are made.
327 ctx->fill_stack_seg(ds_ptr, ds_seg, 0xbaadbadd);
328 ctx->fill_stack_seg(rs_ptr, rs_seg, 0xdaabdaab);
331 template <typename Fixup>
332 void slot_visitor<Fixup>::visit_code_block_objects(code_block* compiled) {
333 visit_handle(&compiled->owner);
334 visit_handle(&compiled->parameters);
335 visit_handle(&compiled->relocation);
338 template <typename Fixup>
339 void slot_visitor<Fixup>::visit_embedded_literals(code_block* compiled) {
340 if (parent->code->uninitialized_p(compiled))
343 auto update_literal_refs = [&](instruction_operand op) {
344 if (op.rel.type() == RT_LITERAL) {
345 cell value = op.load_value(op.pointer);
346 if (!immediate_p(value)) {
347 op.store_value(visit_pointer(value));
351 compiled->each_instruction_operand(update_literal_refs);
354 template <typename Fixup> struct call_frame_code_block_visitor {
357 call_frame_code_block_visitor(Fixup fixup)
360 void operator()(cell frame_top, cell size, code_block* owner, cell addr) {
361 code_block* compiled =
362 Fixup::translated_code_block_map ? owner : fixup.fixup_code(owner);
363 cell fixed_addr = compiled->address_for_offset(owner->offset(addr));
365 *(cell*)frame_top = fixed_addr;
369 template <typename Fixup>
370 void slot_visitor<Fixup>::visit_object_code_block(object* obj) {
371 switch (obj->type()) {
373 word* w = (word*)obj;
375 w->entry_point = fixup.fixup_code(w->code())->entry_point();
378 case QUOTATION_TYPE: {
379 quotation* q = (quotation*)obj;
381 q->entry_point = fixup.fixup_code(q->code())->entry_point();
384 case CALLSTACK_TYPE: {
385 callstack* stack = (callstack*)obj;
386 call_frame_code_block_visitor<Fixup> call_frame_visitor(fixup);
387 parent->iterate_callstack_object(stack, call_frame_visitor, fixup);
393 template <typename Fixup>
394 void slot_visitor<Fixup>::visit_context_code_blocks() {
395 call_frame_code_block_visitor<Fixup> call_frame_visitor(fixup);
396 FACTOR_FOR_EACH(parent->active_contexts) {
397 parent->iterate_callstack(*iter, call_frame_visitor, fixup);
401 template <typename Fixup>
402 void slot_visitor<Fixup>::visit_uninitialized_code_blocks() {
403 std::map<code_block*, cell> new_uninitialized_blocks;
404 FACTOR_FOR_EACH(parent->code->uninitialized_blocks) {
405 new_uninitialized_blocks.insert(
406 std::make_pair(fixup.fixup_code(iter->first), iter->second));
408 parent->code->uninitialized_blocks = new_uninitialized_blocks;
411 template <typename Fixup>
412 void slot_visitor<Fixup>::visit_embedded_code_pointers(code_block* compiled) {
413 if (parent->code->uninitialized_p(compiled))
415 auto update_code_block_refs = [&](instruction_operand op){
416 relocation_type type = op.rel.type();
417 if (type == RT_ENTRY_POINT ||
418 type == RT_ENTRY_POINT_PIC ||
419 type == RT_ENTRY_POINT_PIC_TAIL) {
420 code_block* block = fixup.fixup_code(op.load_code_block());
421 op.store_value(block->entry_point());
424 compiled->each_instruction_operand(update_code_block_refs);
427 template <typename Fixup>
428 void slot_visitor<Fixup>::visit_object(object *ptr) {
430 if (ptr->type() == ALIEN_TYPE)
431 ((alien*)ptr)->update_address();
434 // Pops items from the mark stack and visits them until the stack is
435 // empty. Used when doing a full collection and when collecting to
437 template <typename Fixup>
438 void slot_visitor<Fixup>::visit_mark_stack(std::vector<cell>* mark_stack) {
439 while (!mark_stack->empty()) {
440 cell ptr = mark_stack->back();
441 mark_stack->pop_back();
444 code_block* compiled = (code_block*)(ptr - 1);
445 visit_code_block_objects(compiled);
446 visit_embedded_literals(compiled);
447 visit_embedded_code_pointers(compiled);
449 object* obj = (object*)ptr;
451 visit_object_code_block(obj);
456 // Visits the instruction operands in a code block. If the operand is
457 // a pointer to a code block or data object, then the fixup is applied
458 // to it. Otherwise, if it is an external addess, that address is
459 // recomputed. If it is an untagged number literal (RT_UNTAGGED) or an
460 // immediate value, then nothing is done with it.
461 template <typename Fixup>
462 void slot_visitor<Fixup>::visit_instruction_operands(code_block* block,
464 auto visit_func = [&](instruction_operand op){
465 cell old_offset = rel_base + op.rel.offset();
466 cell old_value = op.load_value(old_offset);
467 switch (op.rel.type()) {
469 if (!immediate_p(old_value)) {
470 op.store_value(visit_pointer(old_value));
475 case RT_ENTRY_POINT_PIC:
476 case RT_ENTRY_POINT_PIC_TAIL:
478 cell offset = TAG(old_value);
479 code_block* compiled = (code_block*)UNTAG(old_value);
480 op.store_value(RETAG(fixup.fixup_code(compiled), offset));
486 op.store_value(parent->compute_external_address(op));
490 block->each_instruction_operand(visit_func);
493 template <typename Fixup>
494 void slot_visitor<Fixup>::visit_partial_objects(cell start,
497 cell *scan_start = (cell*)start + 1;
498 cell *scan_end = scan_start + ((object*)start)->slot_count();
500 scan_start = std::max(scan_start, (cell*)card_start);
501 scan_end = std::min(scan_end, (cell*)card_end);
503 visit_object_array(scan_start, scan_end);
506 template <typename Fixup>
507 template <typename SourceGeneration>
508 cell slot_visitor<Fixup>::visit_card(SourceGeneration* gen,
509 cell index, cell start) {
510 cell heap_base = parent->data->start;
511 cell start_addr = heap_base + index * card_size;
512 cell end_addr = start_addr + card_size;
514 // Forward to the next object whose address is in the card.
515 if (!start || (start + ((object*)start)->size()) < start_addr) {
516 // Optimization because finding the objects in a memory range is
517 // expensive. It helps a lot when tracing consecutive cards.
518 cell gen_start_card = (gen->start - heap_base) / card_size;
520 .find_object_containing_card(index - gen_start_card);
523 while (start && start < end_addr) {
524 visit_partial_objects(start, start_addr, end_addr);
525 if ((start + ((object*)start)->size()) >= end_addr) {
526 // The object can overlap the card boundary, then the
527 // remainder of it will be handled in the next card
528 // tracing if that card is marked.
531 start = gen->next_object_after(start);
536 template <typename Fixup>
537 template <typename SourceGeneration>
538 void slot_visitor<Fixup>::visit_cards(SourceGeneration* gen,
539 card mask, card unmask) {
540 card_deck* decks = parent->data->decks;
541 card_deck* cards = parent->data->cards;
542 cell heap_base = parent->data->start;
544 cell first_deck = (gen->start - heap_base) / deck_size;
545 cell last_deck = (gen->end - heap_base) / deck_size;
547 // Address of last traced object.
549 for (cell di = first_deck; di < last_deck; di++) {
550 if (decks[di] & mask) {
551 decks[di] &= ~unmask;
554 cell first_card = cards_per_deck * di;
555 cell last_card = first_card + cards_per_deck;
557 for (cell ci = first_card; ci < last_card; ci++) {
558 if (cards[ci] & mask) {
559 cards[ci] &= ~unmask;
562 start = visit_card(gen, ci, start);
564 // At end of generation, no need to scan more cards.
573 template <typename Fixup>
574 void slot_visitor<Fixup>::visit_code_heap_roots(std::set<code_block*>* remembered_set) {
575 FACTOR_FOR_EACH(*remembered_set) {
576 code_block* compiled = *iter;
577 visit_code_block_objects(compiled);
578 visit_embedded_literals(compiled);
579 compiled->flush_icache();
583 template <typename Fixup>
584 template <typename TargetGeneration>
585 void slot_visitor<Fixup>::cheneys_algorithm(TargetGeneration* gen, cell scan) {
586 while (scan && scan < gen->here) {
587 visit_object((object*)scan);
588 scan = gen->next_object_after(scan);