factor/vm/full_collector.cpp

#include "master.hpp"

namespace factor
{

full_collector::full_collector(factor_vm *parent_) :
	collector<tenured_space,full_policy>(parent_,parent_->data->tenured,full_policy(parent_)),
	code_visitor(parent,workhorse) {}

void full_collector::trace_code_block(code_block *compiled)
{
	data_visitor.visit_code_block_objects(compiled);
	data_visitor.visit_embedded_literals(compiled);
	code_visitor.visit_embedded_code_pointers(compiled);
}

void full_collector::trace_context_code_blocks()
{
	code_visitor.visit_context_code_blocks();
}

void full_collector::trace_code_roots()
{
	code_visitor.visit_code_roots();
}

void full_collector::trace_object_code_block(object *obj)
{
	code_visitor.visit_object_code_block(obj);
}

/* After a sweep, invalidate any code heap roots which are not marked,
so that if a block makes a tail call to a generic word, and the PIC
compiler triggers a GC, and the caller block gets gets GCd as a result,
the PIC code won't try to overwrite the call site */
void factor_vm::update_code_roots_for_sweep()
{
	std::vector<code_root *>::const_iterator iter = code_roots.begin();
	std::vector<code_root *>::const_iterator end = code_roots.end();

	mark_bits<code_block> *state = &code->allocator->state;

	for(; iter < end; iter++)
	{
		code_root *root = *iter;
		code_block *block = (code_block *)(root->value & (~data_alignment - 1));
		if(root->valid && !state->marked_p(block))
			root->valid = false;
	}
}

void factor_vm::collect_mark_impl(bool trace_contexts_p)
{
	full_collector collector(this);

	mark_stack.clear();

	code->clear_mark_bits();
	data->tenured->clear_mark_bits();

	collector.trace_roots();
	if(trace_contexts_p)
	{
		collector.trace_contexts();
		collector.trace_context_code_blocks();
		collector.trace_code_roots();
	}

	while(!mark_stack.empty())
	{
		cell ptr = mark_stack.back();
		mark_stack.pop_back();

		if(ptr & 1)
		{
			code_block *compiled = (code_block *)(ptr - 1);
			collector.trace_code_block(compiled);
		}
		else
		{
			object *obj = (object *)ptr;
			collector.trace_object(obj);
			collector.trace_object_code_block(obj);
		}
	}

	data->reset_generation(data->tenured);
	data->reset_generation(data->aging);
	data->reset_generation(&nursery);
	code->clear_remembered_set();
}

void factor_vm::collect_sweep_impl()
{
	gc_event *event = current_gc->event;

	if(event) event->started_data_sweep();
	data->tenured->sweep();
	if(event) event->ended_data_sweep();

	update_code_roots_for_sweep();

	if(event) event->started_code_sweep();
	code->sweep();
	if(event) event->ended_code_sweep();
}

void factor_vm::collect_full(bool trace_contexts_p)
{
	collect_mark_impl(trace_contexts_p);
	collect_sweep_impl();

	if(data->low_memory_p())
	{
		/* Full GC did not free up enough memory. Grow the heap. */
		set_current_gc_op(collect_growing_heap_op);
		collect_growing_heap(0,trace_contexts_p);
	}
	else if(data->high_fragmentation_p())
	{
		/* Enough free memory, but it is not contiguous. Perform a
		compaction. */
		set_current_gc_op(collect_compact_op);
		collect_compact_impl(trace_contexts_p);
	}

	code->flush_icache();
}

}