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xo-alloc2: progress on forwarding objects [WIP]

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This commit is contained in:
Roland Conybeare 2025-12-15 00:56:49 -05:00
commit 31a8a8ae48
16 changed files with 499 additions and 37 deletions
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4
include/xo/alloc2/arena/ArenaConfig.hpp
View file

@ -47,7 +47,9 @@ namespace xo {
* present in arena
**/
bool store_header_flag_ = false;
std::uint64_t header_size_mask_ = 0xffffffff;
/** number of bits to represent allocation size **/
std::uint64_t header_size_bits_ = 32;
std::uint64_t header_size_mask_ = (1ul << header_size_bits_) - 1;
/** true to enable debug logging **/
bool debug_flag_ = false;

14
include/xo/alloc2/arena/DArena.hpp
View file

@ -64,7 +64,15 @@ namespace xo {
///@}
/** @defgroup mm-arena-methods **/
///@{
size_type reserved() const { return hi_ - lo_; }
size_type allocated() const { return free_ - lo_; }
size_type committed() const { return committed_z_; }
size_type available() const { return limit_ - free_; }
bool contains(void * addr) const { return (lo_ <= addr) && (addr < hi_); }
/** obtain uncommitted contiguous memory range comprising
* a whole multiple of @p hugepage_z bytes, of at least size @p req_z,
@ -72,12 +80,12 @@ namespace xo {
**/
static range_type map_aligned_range(size_type req_z, size_type hugepage_z);
/** @defgroup mm-arena-methods **/
///@{
/** true if arena is mapped i.e. has a reserved address range **/
bool is_mapped() const { return (lo_ != nullptr) && (hi_ != nullptr); }
/** get header from allocated object address **/
header_type * obj2hdr(void * obj);
///@}
/** @defgroup mm-arena-instance-vars **/

75
include/xo/alloc2/gc/DX1Collector.hpp
View file

@ -40,16 +40,45 @@ namespace xo {
struct CollectorConfig {
using size_type = std::size_t;
/*
* alloc header
* TTTTTTTTTTTTGGGGGZZZZZZZZZZZZ
* < tseq ><gen>< size >
*
* masking
*
* ..432107654321076543210 bit
*
* > < .gen_bits
* 0..............01111111 gen_mask_unshifted
* 0..011111110..........0 gen_mask_shifted
* > < gen_shift
*/
//constexpr std::uint64_t gen_mult() const;
constexpr std::uint64_t gen_shift() const;
constexpr std::uint64_t gen_mask_unshifted() const;
constexpr std::uint64_t gen_mask_shifted() const;
//constexpr std::uint64_t tseq_mult() const;
constexpr std::uint64_t tseq_shift() const;
constexpr std::uint64_t tseq_mask_unshifted() const;
constexpr std::uint64_t tseq_mask_shifted() const;
/** Configuration for collector spaces.
* Will have at least {nursery,tenured} x {from,to} spaces.
* Not using name_ member.
*
* REQUIRE:
* - arena_config_.store_header_flag_ must be true
* - arena_config_.header_size_mask_ must be 0x0000ffff
**/
ArenaConfig arena_config_;
/** number of bits to represent generation **/
std::uint64_t gen_bits_ = 8;
/** number of bits to represent tseq **/
std::uint64_t tseq_bits_ = 24;
/** Number of generations.
* Must be at least 2.
**/
@ -82,7 +111,32 @@ namespace xo {
bool debug_flag_ = false;
};
// ----- GCRunState -----
/** @class GCRunState
* @brief encapsulate state needed while GC is running
**/
struct GCRunState {
GCRunState() : gc_upto_{0} {}
explicit GCRunState(generation gc_upto);
static GCRunState gc_not_running();
static GCRunState gc_upto(generation g);
bool is_running() const { return gc_upto_ > 0; }
generation gc_upto() const { return gc_upto_; }
private:
/** running gc collecting all generations gi < gc_upto **/
generation gc_upto_;
};
// ----- DX1Collector -----
struct DX1Collector {
using header_type = DArena::header_type;
explicit DX1Collector(const CollectorConfig & cfg);
const DArena * get_space(role r, generation g) const { return space_[r][g]; }
@ -90,12 +144,31 @@ namespace xo {
DArena * from_space(generation g) { return get_space(role::from_space(), g); }
DArena * to_space(generation g) { return get_space(role::to_space(), g); }
/** true iff address @p addr allocated from this collector
* in role @p r (according to current GC state)
**/
bool contains(role r, void * addr) const;
/** get allocation size from header **/
std::size_t header2size(header_type hdr) const;
/** get generation counter from alloc header **/
generation header2gen(header_type hdr) const;
/** get tseq from alloc header **/
uint32_t header2tseq(header_type hdr) const;
/** true iff original alloc has been replaced by a forwarding pointer **/
bool is_forwarding_header(header_type hdr) const;
/** reverse to-space and from-space roles for generation g **/
void reverse_roles(generation g);
public:
/** garbage collector configuration **/
CollectorConfig config_;
/** current gc state **/
GCRunState runstate_;
/** collector-managed memory here.
* - space_[1] is from-space
* - space_[0] is to-space

60
include/xo/alloc2/gc/IAllocator_DX1Collector.hpp Normal file
View file

@ -0,0 +1,60 @@
/** @file IAllocator_DX1Collector.hpp
*
* @author Roland Conybeare, Dec 2025
**/
#pragma once
#include "alloc2/alloc/Allocator.hpp"
#include "alloc2/alloc/IAllocator_Xfer.hpp"
#include "DX1Collector.hpp"
namespace xo {
namespace mm { struct IAllocator_DX1Collector; }
namespace facet {
template <>
struct FacetImplementation<xo::mm::AAllocator,
xo::mm::DX1Collector>
{
using ImplType = xo::mm::IAllocator_Xfer<xo::mm::DX1Collector,
xo::mm::IAllocator_DX1Collector>;
};
}
namespace mm {
/* changes here coordinate with
* AAllocator AAllocator.hpp
* IAllocator_Any IAllocator_Any.hpp
* IAllocator_Xfer IAllocator_Xfer.hpp
* RAllocator RCollector.hpp
*/
struct IAllocator_DX1Collector {
using size_type = std::size_t;
using value_type = std::byte *;
// todo: available()
static std::string_view name(const DX1Collector &) noexcept;
static size_type reserved(const DX1Collector &) noexcept;
static size_type size(const DX1Collector &) noexcept;
static size_type committed(const DX1Collector &) noexcept;
static size_type available(const DX1Collector &) noexcept;
static size_type allocated(const DX1Collector &) noexcept;
static bool contains(const DX1Collector & d, const void * p) noexcept;
static AllocatorError last_error(const DX1Collector &) noexcept;
static bool expand(DX1Collector & d, size_type z) noexcept;
static value_type alloc(DX1Collector & d, size_type z);
static value_type super_alloc(DX1Collector & d, size_type z);
static value_type sub_alloc(DX1Collector & d, size_type z, bool complete);
static void clear(DX1Collector & d);
static void destruct_data(DX1Collector & d);
};
} /*namespace mm*/
} /*namespace xo*/
/* end IAllocator_DX1Collector.hpp */

12
include/xo/alloc2/gc/ICollector_Any.hpp
View file

@ -29,14 +29,14 @@ namespace xo {
int32_t _typeseq() const noexcept override { return s_typeseq; }
// const methods
[[noreturn]] size_type allocated(Copaque, generation, role) const noexcept { _fatal(); }
[[noreturn]] size_type reserved(Copaque, generation, role) const noexcept { _fatal(); }
[[noreturn]] size_type committed(Copaque, generation, role) const noexcept { _fatal(); }
[[noreturn]] size_type allocated(Copaque, generation, role) const noexcept override { _fatal(); }
[[noreturn]] size_type reserved(Copaque, generation, role) const noexcept override { _fatal(); }
[[noreturn]] size_type committed(Copaque, generation, role) const noexcept override { _fatal(); }
// non-const methods
[[noreturn]] void install_type(Opaque, int32_t, IGCObject_Any &) noexcept { _fatal(); }
[[noreturn]] void add_gc_root(Opaque, int32_t, Opaque *) { _fatal(); }
[[noreturn]] void forward_inplace(Opaque, obj<AGCObject> *) { _fatal(); }
[[noreturn]] void install_type(Opaque, int32_t, IGCObject_Any &) noexcept override { _fatal(); }
[[noreturn]] void add_gc_root(Opaque, int32_t, Opaque *) override { _fatal(); }
[[noreturn]] void forward_inplace(Opaque, obj<AGCObject> *) override { _fatal(); }
private:
[[noreturn]] static void _fatal();

26
include/xo/alloc2/gc/ICollector_DX1Collector.hpp
View file

@ -12,7 +12,9 @@ namespace xo {
namespace facet {
template <>
struct FacetImplementation<xo::mm::ACollector, xo::mm::DX1Collector> {
struct FacetImplementation<xo::mm::ACollector,
xo::mm::DX1Collector>
{
using ImplType = xo::mm::ICollector_Xfer<xo::mm::DX1Collector,
xo::mm::ICollector_DX1Collector>;
};
@ -27,16 +29,22 @@ namespace xo {
*/
struct ICollector_DX1Collector {
using size_type = std::size_t;
using header_type = DArena::header_type;
static size_type allocated(const DX1Collector & d, generation g, role r) {
const DArena * arena = d.get_space(r, g);
static bool check_move_policy(const DX1Collector & d,
header_type alloc_hdr,
void * object_data);
if (arena) [[likely]] {
return arena->allocated();
} else {
return 0;
}
}
// todo: available()
static size_type allocated(const DX1Collector & d, generation g, role r);
static size_type reserved(const DX1Collector & d, generation g, role r);
static size_type committed(const DX1Collector & d, generation g, role r);
static void install_type(DX1Collector & d,
int32_t seq, IGCObject_Any & iface);
static void add_gc_root(DX1Collector & d, int32_t tseq, Opaque * root);
static void forward_inplace(DX1Collector & d, obj<AGCObject> * lhs);
static int32_t s_typeseq;
static bool _valid;

10
include/xo/alloc2/gc/ICollector_Xfer.hpp
View file

@ -35,22 +35,22 @@ namespace xo {
return I::allocated(_dcast(d), g, r);
}
size_type reserved(Copaque d, generation g, role r) const noexcept override {
return I::reserved(d,g,r);
return I::reserved(_dcast(d), g, r);
}
size_type committed(Copaque d, generation g, role r) const noexcept override {
return I::committed(d,g,r);
return I::committed(_dcast(d), g, r);
}
// non-const methods
void install_type(Opaque d, int32_t tseq, IGCObject_Any & iface) override {
I::install_type(d, tseq, iface);
I::install_type(_dcast(d), tseq, iface);
}
void add_gc_root(Opaque d, int32_t tseq, Opaque * root) override {
I::add_gc_root(d, tseq, root);
I::add_gc_root(_dcast(d), tseq, root);
}
void forward_inplace(Opaque d, obj<AGCObject> * lhs) override {
I::forward_inplace(d, lhs);
I::forward_inplace(_dcast(d), lhs);
}
private:

10
include/xo/alloc2/gc/RCollector.hpp
View file

@ -23,12 +23,12 @@ namespace xo {
RCollector(DataPtr data) : Object{std::move(data)} {}
int32_t _typeseq() const noexcept { return O::iface()->_typeseq(); }
size_type allocated(generation g, role r) const noexcept { return O::iface()->allocated(O::data()); }
size_type reserved(generation g, role r) const noexcept { return O::iface()->reserved(O::data()); }
size_type committed(generation g, role r) const noexcept { return O::iface()->committed(O::data()); }
size_type allocated(generation g, role r) const noexcept { return O::iface()->allocated(O::data(), g, r); }
size_type reserved(generation g, role r) const noexcept { return O::iface()->reserved(O::data(), g, r); }
size_type committed(generation g, role r) const noexcept { return O::iface()->committed(O::data(), g, r); }
void install_type(int32_t tseq, IGCObject_Any & iface) { return O::iface()->install_type(O::data()); }
void add_gc_root(int32_t tseq, Opaque * root) { O::iface()->add_gc_root(O::data()); }
void install_type(int32_t tseq, IGCObject_Any & iface) { return O::iface()->install_type(O::data(), tseq, iface); }
void add_gc_root(int32_t tseq, Opaque * root) { O::iface()->add_gc_root(O::data(), tseq, root); }
void forward_inplace(obj<AGCObject> * lhs) { O::iface()->forward_inplace(O::data(), lhs); }

4
include/xo/alloc2/gc/role.hpp
View file

@ -21,9 +21,9 @@ namespace xo {
operator value_type() const { return role_; }
std::uint32_t role_;
value_type role_ = 0;
};
} /*namespace mm*/
} /*namespace xo*/
/* end role,hpp */
/* end role.hpp */

1
src/alloc2/CMakeLists.txt
View file

@ -10,6 +10,7 @@ set(SELF_SRCS
ICollector_Any.cpp
IGCObject_Any.cpp
IAllocator_DX1Collector.cpp
ICollector_DX1Collector.cpp
DX1Collector.cpp

10
src/alloc2/DArena.cpp
View file

@ -238,6 +238,16 @@ namespace xo {
error_count_ = 0;
last_error_ = AllocatorError();
}
DArena::header_type *
DArena::obj2hdr(void * obj)
{
assert(config_.store_header_flag_);
return (header_type *)((byte *)obj - sizeof(header_type));
}
}
} /*namespace xo*/

117
src/alloc2/DX1Collector.cpp
View file

@ -4,15 +4,84 @@
**/
#include "gc/DX1Collector.hpp"
#include "gc/generation.hpp"
#include <_types/_uint32_t.h>
#include <cassert>
#include <cstdint>
namespace xo {
namespace mm {
#ifdef NOT_USING
constexpr std::uint64_t
CollectorConfig::gen_mult() const {
return 1ul << arena_config_.header_size_bits_;
}
#endif
constexpr std::uint64_t
CollectorConfig::gen_shift() const {
return arena_config_.header_size_bits_;
}
constexpr std::uint64_t
CollectorConfig::gen_mask_unshifted() const {
return (1ul << gen_bits_) - 1;
}
constexpr std::uint64_t
CollectorConfig::gen_mask_shifted() const {
return gen_mask_unshifted() << arena_config_.header_size_bits_;
}
#ifdef NOT_USING
constexpr std::uint64_t
CollectorConfig::tseq_mult() const {
return 1ul << (gen_bits_ + arena_config_.header_size_bits_);
}
#endif
constexpr std::uint64_t
CollectorConfig::tseq_shift() const {
return gen_bits_ + arena_config_.header_size_bits_;
}
constexpr std::uint64_t
CollectorConfig::tseq_mask_unshifted() const {
return (1ul << tseq_bits_) - 1;
}
constexpr std::uint64_t
CollectorConfig::tseq_mask_shifted() const {
return tseq_mask_unshifted() << (gen_bits_ + arena_config_.header_size_bits_);
}
// ----- GCRunState -----
GCRunState::GCRunState(generation gc_upto)
: gc_upto_{gc_upto}
{}
GCRunState
GCRunState::gc_not_running()
{
return GCRunState(generation(0));
}
GCRunState
GCRunState::gc_upto(generation g)
{
return GCRunState(generation(g + 1));
}
// ----- DX1Collector -----
DX1Collector::DX1Collector(const CollectorConfig & cfg) : config_{cfg}
{
assert(config_.arena_config_.header_size_bits_ + config_.gen_bits_ + config_.tseq_bits_ <= 64);
for (uint32_t igen = 0, ngen = cfg.n_generation_; igen < ngen; ++igen) {
space_storage_[0][igen] = std::move(DArena::map(cfg.arena_config_));
space_storage_[1][igen] = std::move(DArena::map(cfg.arena_config_));
space_storage_[0][igen] = DArena::map(cfg.arena_config_);
space_storage_[1][igen] = DArena::map(cfg.arena_config_);
space_[role::to_space()][igen] = &space_storage_[0][igen];
space_[role::from_space()][igen] = &space_storage_[1][igen];
@ -24,6 +93,50 @@ namespace xo {
}
}
bool
DX1Collector::contains(role r, void * addr) const
{
for (generation gi{0}; gi < config_.n_generation_; ++gi) {
if (get_space(r, gi)->contains(addr))
return true;
}
return false;
}
std::size_t
DX1Collector::header2size(header_type hdr) const
{
uint32_t z = (hdr & config_.arena_config_.header_size_mask_);
return z;
}
generation
DX1Collector::header2gen(header_type hdr) const
{
uint32_t g = (hdr & config_.gen_mask_shifted()) >> config_.gen_shift();
assert(g < c_max_generation);
return generation(g);
}
uint32_t
DX1Collector::header2tseq(header_type hdr) const
{
uint32_t tseq = (hdr & config_.tseq_mask_shifted()) >> config_.tseq_shift();
return tseq;
}
bool
DX1Collector::is_forwarding_header(header_type hdr) const
{
/** all 1 bits to flag forwarding pointer **/
return header2tseq(hdr) == config_.tseq_mask_shifted();
}
void
DX1Collector::reverse_roles(generation g) {
assert(g < config_.n_generation_);

6
src/alloc2/IAllocator_DArena.cpp
View file

@ -24,7 +24,7 @@ namespace xo {
size_t
IAllocator_DArena::reserved(const DArena & s) noexcept {
return s.hi_ - s.lo_;
return s.reserved();
}
size_t
@ -34,12 +34,12 @@ namespace xo {
size_t
IAllocator_DArena::committed(const DArena & s) noexcept {
return s.committed_z_;
return s.committed();
}
size_t
IAllocator_DArena::available(const DArena & s) noexcept {
return s.limit_ - s.free_;
return s.available();
}
size_t

11
src/alloc2/IAllocator_DX1Collector.cpp Normal file
View file

@ -0,0 +1,11 @@
/** @file IAllocator_DX1Collector.cpp
*
* @author Roland Conybeare, Dec 2025
**/
namespace xo {
namespace mm {
} /*namespace mm*/
} /*namespace xo*/
/* end IAllocator_DX1Collector.cpp */

173
src/alloc2/ICollector_DX1Collector.cpp
View file

@ -4,9 +4,182 @@
**/
#include "gc/ICollector_DX1Collector.hpp"
#include "GCObject.hpp"
namespace xo {
namespace mm {
using size_type = ICollector_DX1Collector::size_type;
using std::byte;
namespace {
size_type
stat_helper(const DX1Collector & d,
size_type (DArena::* getter)() const,
generation g,
role r)
{
const DArena * arena = d.get_space(r, g);
if (arena) [[likely]]
return (arena->*getter)();
return 0;
}
}
size_type
ICollector_DX1Collector::reserved(const DX1Collector & d, generation g, role r)
{
return stat_helper(d, &DArena::reserved, g, r);
}
size_type
ICollector_DX1Collector::allocated(const DX1Collector & d, generation g, role r)
{
return stat_helper(d, &DArena::allocated, g, r);
}
size_type
ICollector_DX1Collector::committed(const DX1Collector & d, generation g, role r)
{
return stat_helper(d, &DArena::committed, g, r);
}
void
ICollector_DX1Collector::install_type(DX1Collector & d,
std::int32_t tseq,
IGCObject_Any & iface)
{
(void)d;
(void)tseq;
(void)iface;
assert(false);
}
void
ICollector_DX1Collector::add_gc_root(DX1Collector & d,
int32_t tseq,
Opaque * root)
{
(void)d;
(void)tseq;
(void)root;
assert(false);
}
void
ICollector_DX1Collector::forward_inplace(DX1Collector & d,
obj<AGCObject> * lhs)
{
assert(d.runstate_.is_running());
/*
* lhs obj<AGCObject>
* | +---------+ +---+-+----+
* \--->| .iface | | T |G|size| header
* +---------+ object_data +---+-+----+
* | .data x----------------->| alloc |
* +---------+ | data |
* | for |
* | instance |
* | ... |
* +----------+
*/
void * object_data = (byte *)(*lhs).opaque_data();
if (!d.contains(role::from_space(), object_data)) {
/* *lhs isn't in GC-allocated space.
*
* This happens for a modest number of global
* constant, for example DBoolean {true, false}.
*
* It's important we recognize these up front.
* Since not allocated from GC, they don't have
* an alloc-header.
*/
return;
}
/** NOTE: for form's sake:
* better to lookup actual arena that
* allocated object data.
*
**/
DArena * some_arena = d.to_space(generation(0));
DArena::header_type * p_header
= some_arena->obj2hdr(object_data);
DArena::header_type alloc_hdr = *p_header;
/* recover allocation size */
std::size_t alloc_z = some_arena->config_.header_size_mask_ & alloc_hdr;
/* need to be able to fit forwarding pointer
* in place of forwarded object.
*
* This is guaranteed anyway, by alignment rules
*/
assert(alloc_z > sizeof(uintptr_t));
if (d.is_forwarding_header(alloc_hdr)) {
/* *lhs already refers to a forwarding pointer */
/*
* lhs obj<AGCObject>
* | +---------+ +---+-+----+
* \--->| .iface | |FWD|G|size| alloc_hdr
* +---------+ object_data +---+-+----+
* | .data x----------------->| x-------->
* +---------+ | | dest
* | |
* +----------+
*/
void * dest = *(void**)object_data;
/* update *lhs in-place */
(*lhs).reset_opaque(dest);
} else if (check_move_policy(d, alloc_hdr, object_data)) {
/* copy object *lhs + replace with forwarding pointer */
/* which arena are we writing to? need allocator interface */
assert(false);
#ifdef NOT_YET
// to do this need IAllocator_DX1Collector fully implemented
void * copy = (*lhs).shallow_copy(xxx);
xxx mm xxx;
#endif
} else {
/* object doesn't need to move.
* e.g. incremental collection + object is tenured
*/
}
}
bool
ICollector_DX1Collector::check_move_policy(const DX1Collector & d,
header_type alloc_hdr,
void * object_data)
{
(void)object_data;
// when gc is moving objects, to- and from- spaces have been
// reversed: forwarding pointers are located in from-space and
// refer to to-space.
generation g = d.header2gen(alloc_hdr);
assert(d.runstate_.is_running());
return (g < d.runstate_.gc_upto());
}
} /*namespace mm*/
} /*namespace xo*/

3
utest/Collector.test.cpp
View file

@ -98,6 +98,9 @@ namespace xo {
/* typed collector */
obj<ACollector, DX1Collector> x1(&gc);
REQUIRE(x1.iface());
REQUIRE(x1.data());
}
}
}