From 63e2fd6f3cd0449176242ffdc7273c30e3c25440 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Thu, 2 Apr 2026 20:35:22 -0400
Subject: [PATCH] xo-gc: move header query aux method impls to GCObjectStore

---
 xo-gc/include/xo/gc/DX1Collector.hpp  |  6 ++---
 xo-gc/include/xo/gc/GCObjectStore.hpp | 16 +++++++++++++
 xo-gc/src/gc/DX1Collector.cpp         | 19 ++++-----------
 xo-gc/src/gc/GCObjectStore.cpp        | 33 +++++++++++++++++++++++++++
 4 files changed, 57 insertions(+), 17 deletions(-)

diff --git a/xo-gc/include/xo/gc/DX1Collector.hpp b/xo-gc/include/xo/gc/DX1Collector.hpp
index 6fd48b98..6a53b2b8 100644
--- a/xo-gc/include/xo/gc/DX1Collector.hpp
+++ b/xo-gc/include/xo/gc/DX1Collector.hpp
@@ -143,9 +143,9 @@ namespace xo {
             using GCMoveCheckpoint = std::array<std::byte *, c_max_generation>;
             using MutationLog = DArenaVector<MutationLogEntry>;
             using typeseq = xo::facet::typeseq;
-            using size_type = DArena::size_type;
-            using value_type = DArena::value_type;
-            using header_type = DArena::header_type;
+            using size_type = GCObjectStore::size_type;
+            using value_type = GCObjectStore::value_type;
+            using header_type = GCObjectStore::header_type;
 
             /** hard max typeseq for collector-registered types **/
             static constexpr size_t c_max_typeseq = 4096;
diff --git a/xo-gc/include/xo/gc/GCObjectStore.hpp b/xo-gc/include/xo/gc/GCObjectStore.hpp
index e1a3b940..44dc579b 100644
--- a/xo-gc/include/xo/gc/GCObjectStore.hpp
+++ b/xo-gc/include/xo/gc/GCObjectStore.hpp
@@ -6,6 +6,7 @@
 #pragma once
 
 #include "generation.hpp"
+#include "object_age.hpp"
 #include <xo/alloc2/role.hpp>
 #include <xo/arena/DArena.hpp>
 #include <xo/arena/ArenaConfig.hpp>
@@ -17,6 +18,11 @@ namespace xo {
         /** @brief container to hold gc-aware objects for X1 collector
          **/
         class GCObjectStore {
+        public:
+            using header_type = DArena::header_type;
+            using value_type = DArena::value_type;
+            using size_type = DArena::size_type;
+
         public:
             GCObjectStore(const ArenaConfig & arena_cfg, uint32_t ngen, bool debug_flag);
 
@@ -31,6 +37,16 @@ namespace xo {
              **/
             Generation generation_of(role r, const void * addr) const noexcept;
 
+            /** get allocation size from header **/
+            std::size_t header2size(header_type hdr) const noexcept;
+            /** get generation counter from alloc header **/
+            object_age header2age(header_type hdr) const noexcept;
+            /** get tseq from alloc header **/
+            uint32_t header2tseq(header_type hdr) const noexcept;
+
+            /** true iff original alloc has been replaced by a forwarding pointer **/
+            bool is_forwarding_header(header_type hdr) const noexcept;
+
             /** Call @p visitor for each memory pool owned by this store **/
             void visit_pools(const MemorySizeVisitor & visitor) const;
 
diff --git a/xo-gc/src/gc/DX1Collector.cpp b/xo-gc/src/gc/DX1Collector.cpp
index deac4bfb..091734e9 100644
--- a/xo-gc/src/gc/DX1Collector.cpp
+++ b/xo-gc/src/gc/DX1Collector.cpp
@@ -534,34 +534,25 @@ namespace xo {
         size_type
         DX1Collector::header2size(header_type hdr) const noexcept
         {
-            uint32_t z = config_.arena_config_.header_.size(hdr);
-
-            return z;
+            return gco_store_.header2size(hdr);
         }
 
         object_age
         DX1Collector::header2age(header_type hdr) const noexcept
         {
-            uint32_t age = config_.arena_config_.header_.age(hdr);
-
-            assert(age < c_max_object_age);
-
-            return object_age(age);
+            return gco_store_.header2age(hdr);
         }
 
         uint32_t
         DX1Collector::header2tseq(header_type hdr) const noexcept
         {
-            uint32_t tseq = config_.arena_config_.header_.tseq(hdr);
-
-            return tseq;
+            return gco_store_.header2tseq(hdr);
         }
 
         bool
         DX1Collector::is_forwarding_header(header_type hdr) const noexcept
         {
-            /** forwarding pointer encoded as sentinel tseq **/
-            return config_.arena_config_.header_.is_forwarding_tseq(hdr);
+            return gco_store_.is_forwarding_header(hdr);
         }
 
         bool
@@ -1527,7 +1518,7 @@ namespace xo {
 
                 assert(src_hdr && dest_hdr);
 
-                if (header2age(*src_hdr) <= header2age(*dest_hdr)) {
+                if (this->header2age(*src_hdr) <= this->header2age(*dest_hdr)) {
                     // source and destination have the same age;
                     // therefore are always collected on the same set of GC cycles
                     // -> no need to remember separately.
diff --git a/xo-gc/src/gc/GCObjectStore.cpp b/xo-gc/src/gc/GCObjectStore.cpp
index 7e4d80a5..b0948eb7 100644
--- a/xo-gc/src/gc/GCObjectStore.cpp
+++ b/xo-gc/src/gc/GCObjectStore.cpp
@@ -75,6 +75,39 @@ namespace xo {
             return Generation::sentinel();
         }
 
+        auto
+        GCObjectStore::header2size(header_type hdr) const noexcept -> size_type
+        {
+            uint32_t z = arena_config_.header_.size(hdr);
+
+            return z;
+        }
+
+        object_age
+        GCObjectStore::header2age(header_type hdr) const noexcept
+        {
+            uint32_t age = arena_config_.header_.age(hdr);
+
+            assert(age < c_max_object_age);
+
+            return object_age(age);
+        }
+
+        uint32_t
+        GCObjectStore::header2tseq(header_type hdr) const noexcept
+        {
+            uint32_t tseq = arena_config_.header_.tseq(hdr);
+
+            return tseq;
+        }
+
+        bool
+        GCObjectStore::is_forwarding_header(header_type hdr) const noexcept
+        {
+            /** forwarding pointer encoded as sentinel tseq **/
+            return arena_config_.header_.is_forwarding_tseq(hdr);
+        }
+
         void
         GCObjectStore::visit_pools(const MemorySizeVisitor & visitor) const
         {