rt: Implement cycle collection marking. Simple cycles can now be detected.
This commit is contained in:
Patrick Walton
parent
a993621e43
commit
ad3b9c41b4
1 changed files with 244 additions and 6 deletions
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@ -5,9 +5,11 @@
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#include "rust_internal.h"
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#include "rust_shape.h"
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#include "rust_task.h"
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#include <cassert>
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#include <cstdio>
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#include <cstdlib>
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#include <map>
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#include <set>
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#include <vector>
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#include <stdint.h>
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@ -23,7 +25,7 @@ typedef std::map<void *,uintptr_t> irc_map;
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class irc : public shape::data<irc,shape::ptr> {
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friend class shape::data<irc,shape::ptr>;
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irc_map ircs;
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irc_map &ircs;
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irc(const irc &other, const shape::ptr &in_dp)
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: shape::data<irc,shape::ptr>(other.task, other.align, other.sp,
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@ -114,10 +116,13 @@ class irc : public shape::data<irc,shape::ptr> {
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return;
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// Bump the internal reference count of the box.
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if (ircs.find((void *)dp) == ircs.end())
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ircs[(void *)dp] = 1;
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else
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++ircs[(void *)dp];
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if (ircs.find((void *)ref_count_dp) == ircs.end()) {
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//DPRINT("setting internal reference count for %p\n",
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// (void *)ref_count_dp);
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ircs[(void *)ref_count_dp] = 1;
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} else {
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++ircs[(void *)ref_count_dp];
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}
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// Do not traverse the contents of this box; it's in the allocation
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// somewhere, so we're guaranteed to come back to it (if we haven't
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@ -167,7 +172,8 @@ irc::compute_ircs(rust_task *task, irc_map &ircs) {
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type_desc *tydesc = begin->second;
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DPRINT("determining internal ref counts: %p, tydesc=%p\n", p, tydesc);
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//DPRINT("determining internal ref counts: %p, tydesc=%p\n", p,
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//tydesc);
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shape::arena arena;
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shape::type_param *params =
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@ -187,10 +193,242 @@ irc::compute_ircs(rust_task *task, irc_map &ircs) {
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}
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// Root finding
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void
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find_roots(rust_task *task, irc_map &ircs, std::vector<void *> &roots) {
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std::map<void *,type_desc *>::iterator begin(task->local_allocs.begin()),
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end(task->local_allocs.end());
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while (begin != end) {
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void *alloc = begin->first;
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uintptr_t *ref_count_ptr = reinterpret_cast<uintptr_t *>(alloc);
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uintptr_t ref_count = *ref_count_ptr;
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uintptr_t irc;
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if (ircs.find(alloc) != ircs.end())
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irc = ircs[alloc];
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else
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irc = 0;
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if (irc < ref_count) {
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// This allocation must be a root, because the internal reference
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// count is smaller than the total reference count.
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//DPRINT("root found: %p, irc %lu, ref count %lu\n", alloc, irc,
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// ref_count);
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roots.push_back(alloc);
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} else {
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//DPRINT("nonroot found: %p, ref count %lu\n", alloc, ref_count);
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/*assert(irc == ref_count && "Internal reference count must be "
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"less than or equal to the total reference count!");*/
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}
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++begin;
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}
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}
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// Marking
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class mark : public shape::data<mark,shape::ptr> {
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friend class shape::data<mark,shape::ptr>;
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std::set<void *> &marked;
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mark(const mark &other, const shape::ptr &in_dp)
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: shape::data<mark,shape::ptr>(other.task, other.align, other.sp,
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other.params, other.tables, in_dp),
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marked(other.marked) {}
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mark(const mark &other,
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const uint8_t *in_sp,
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const shape::type_param *in_params,
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const rust_shape_tables *in_tables = NULL)
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: shape::data<mark,shape::ptr>(other.task,
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other.align,
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in_sp,
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in_params,
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in_tables ? in_tables : other.tables,
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other.dp),
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marked(other.marked) {}
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mark(const mark &other,
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const uint8_t *in_sp,
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const shape::type_param *in_params,
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const rust_shape_tables *in_tables,
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shape::ptr in_dp)
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: shape::data<mark,shape::ptr>(other.task,
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other.align,
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in_sp,
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in_params,
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in_tables,
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in_dp),
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marked(other.marked) {}
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mark(rust_task *in_task,
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bool in_align,
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const uint8_t *in_sp,
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const shape::type_param *in_params,
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const rust_shape_tables *in_tables,
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uint8_t *in_data,
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std::set<void *> &in_marked)
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: shape::data<mark,shape::ptr>(in_task, in_align, in_sp, in_params,
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in_tables, in_data),
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marked(in_marked) {}
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void walk_vec(bool is_pod, uint16_t sp_size) {
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if (is_pod || shape::get_dp<void *>(dp) == NULL)
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return; // There can't be any outbound pointers from this.
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std::pair<uint8_t *,uint8_t *> data_range(get_vec_data_range(dp));
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if (data_range.second - data_range.first > 100000)
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abort(); // FIXME: Temporary sanity check.
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mark sub(*this, data_range.first);
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shape::ptr data_end = sub.end_dp = data_range.second;
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while (sub.dp < data_end) {
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sub.walk_reset();
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align = true;
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}
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}
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void walk_tag(shape::tag_info &tinfo, uint32_t tag_variant) {
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shape::data<mark,shape::ptr>::walk_variant(tinfo, tag_variant);
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}
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void walk_box() {
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shape::data<mark,shape::ptr>::walk_box_contents();
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}
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void walk_fn() {
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shape::data<mark,shape::ptr>::walk_fn_contents(dp);
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}
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void walk_obj() {
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shape::data<mark,shape::ptr>::walk_obj_contents(dp);
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}
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void walk_res(const shape::rust_fn *dtor, unsigned n_params,
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const shape::type_param *params, const uint8_t *end_sp,
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bool live) {
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while (this->sp != end_sp) {
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this->walk();
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align = true;
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}
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}
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void walk_subcontext(mark &sub) { sub.walk(); }
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void walk_box_contents(mark &sub, shape::ptr &ref_count_dp) {
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if (!ref_count_dp)
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return;
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if (marked.find((void *)ref_count_dp) != marked.end())
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return; // Skip to avoid chasing cycles.
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marked.insert((void *)ref_count_dp);
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sub.walk();
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}
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void walk_struct(const uint8_t *end_sp) {
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while (this->sp != end_sp) {
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this->walk();
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align = true;
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}
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}
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void walk_variant(shape::tag_info &tinfo, uint32_t variant_id,
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const std::pair<const uint8_t *,const uint8_t *>
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variant_ptr_and_end);
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template<typename T>
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inline void walk_number() { /* no-op */ }
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public:
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static void do_mark(rust_task *task, const std::vector<void *> &roots,
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std::set<void *> &marked);
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};
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void
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mark::walk_variant(shape::tag_info &tinfo, uint32_t variant_id,
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const std::pair<const uint8_t *,const uint8_t *>
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variant_ptr_and_end) {
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mark sub(*this, variant_ptr_and_end.first, tinfo.params);
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assert(variant_id < 256); // FIXME: Temporary sanity check.
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const uint8_t *variant_end = variant_ptr_and_end.second;
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while (sub.sp < variant_end) {
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sub.walk();
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align = true;
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}
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}
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void
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mark::do_mark(rust_task *task, const std::vector<void *> &roots,
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std::set<void *> &marked) {
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std::vector<void *>::const_iterator begin(roots.begin()),
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end(roots.end());
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while (begin != end) {
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void *alloc = *begin;
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if (marked.find(alloc) == marked.end()) {
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marked.insert(alloc);
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uint8_t *p = reinterpret_cast<uint8_t *>(alloc);
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p += sizeof(uintptr_t); // Skip over the reference count.
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type_desc *tydesc = task->local_allocs[*begin];
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//DPRINT("marking: %p, tydesc=%p\n", p, tydesc);
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shape::arena arena;
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shape::type_param *params =
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shape::type_param::from_tydesc(tydesc, arena);
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#if 0
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shape::log log(task, true, tydesc->shape, params,
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tydesc->shape_tables, p, std::cerr);
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log.walk();
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DPRINT("\n");
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#endif
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mark mark(task, true, tydesc->shape, params, tydesc->shape_tables,
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p, marked);
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mark.walk();
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}
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++begin;
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}
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}
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void
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sweep(rust_task *task, const std::set<void *> &marked) {
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std::map<void *,type_desc *>::iterator begin(task->local_allocs.begin()),
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end(task->local_allocs.end());
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while (begin != end) {
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void *alloc = begin->first;
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if (marked.find(alloc) == marked.end()) {
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DPRINT("object is part of a cycle: %p\n", alloc);
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}
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++begin;
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}
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}
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void
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do_cc(rust_task *task) {
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DPRINT("cc; n allocs = %lu\n", task->local_allocs.size());
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irc_map ircs;
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irc::compute_ircs(task, ircs);
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std::vector<void *> roots;
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find_roots(task, ircs, roots);
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std::set<void *> marked;
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mark::do_mark(task, roots, marked);
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sweep(task, marked);
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}
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void
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