From caf2cb3e9be5afaf186b89b84aaaba8d166ce17a Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Sun, 29 Mar 2026 19:47:15 -0400
Subject: [PATCH] xo-gc stack: + gc-location-of() primitive

---
 include/xo/gc/DX1Collector.hpp                |  3 +++
 .../xo/gc/detail/ICollector_DX1Collector.hpp  |  4 ++++
 src/gc/DX1Collector.cpp                       | 22 +++++++++++++++++++
 src/gc/facet/ICollector_DX1Collector.cpp      |  6 +++++
 4 files changed, 35 insertions(+)

diff --git a/include/xo/gc/DX1Collector.hpp b/include/xo/gc/DX1Collector.hpp
index c1e1669..8279c8e 100644
--- a/include/xo/gc/DX1Collector.hpp
+++ b/include/xo/gc/DX1Collector.hpp
@@ -223,6 +223,9 @@ namespace xo {
             /** memory (virtual addresses) reserved for generation @p g in role @p r **/
             size_type reserved(Generation g, role r) const noexcept;
 
+            /** very similar to generation_of(), but satisfies ACollector api **/
+            std::int32_t locate_address(const void * addr) const noexcept;
+
             // ----- full statistics -----
 
             /** Report gc statistics as a dictionary.
diff --git a/include/xo/gc/detail/ICollector_DX1Collector.hpp b/include/xo/gc/detail/ICollector_DX1Collector.hpp
index f7db4b9..f73cb01 100644
--- a/include/xo/gc/detail/ICollector_DX1Collector.hpp
+++ b/include/xo/gc/detail/ICollector_DX1Collector.hpp
@@ -53,6 +53,10 @@ namespace xo {
             static size_type committed(const DX1Collector & self, Generation g, role r) noexcept;
             /** address space reserved for this collector **/
             static size_type reserved(const DX1Collector & self, Generation g, role r) noexcept;
+            /** Location of object in collector. -1 if not in collector memory.
+Other negative values represent collector error states (good luck!).
+Exact meaning of non-negative values up to collector implementation **/
+            static std::int32_t locate_address(const DX1Collector & self, const void * addr) noexcept;
             /** true if gc responsible for data at @p addr, and data belongs to role @p r **/
             static bool contains(const DX1Collector & self, role r, const void * addr) noexcept;
             /** true iff gc-aware object of type @p tseq is installed in this collector **/
diff --git a/src/gc/DX1Collector.cpp b/src/gc/DX1Collector.cpp
index d9f09b8..8a90a0b 100644
--- a/src/gc/DX1Collector.cpp
+++ b/src/gc/DX1Collector.cpp
@@ -342,6 +342,27 @@ namespace xo {
             return stat_helper(*this, &DArena::reserved, g, r);
         }
 
+        std::int32_t
+        DX1Collector::locate_address(const void * addr) const noexcept
+        {
+            Generation g;
+
+            g = this->generation_of(role::to_space(), addr);
+
+            if (!g.is_sentinel())
+                return g;
+
+            g = this->generation_of(role::from_space(), addr);
+
+            if (!g.is_sentinel()) {
+                // use negative values for
+
+                return -1 - g;
+            }
+
+            return -1;
+        }
+
         // editor bait: report-gc-statistics
         bool
         DX1Collector::report_statistics(obj<AAllocator> mm,
@@ -362,6 +383,7 @@ namespace xo {
             //
             ok &= rpt->upsert_cstr(mm, "n-generation", DInteger::box(mm, config_.n_generation_));
             ok &= rpt->upsert_cstr(mm, "n-survive-threshold", DInteger::box(mm, config_.n_survive_threshold_));
+            ok &= rpt->upsert_cstr(mm, "allow-incremental-gc", DBoolean::box(mm, config_.allow_incremental_gc_));
             ok &= rpt->upsert_cstr(mm, "allocated", DInteger::box(mm, this->allocated()));
             ok &= rpt->upsert_cstr(mm, "committed", DInteger::box(mm, this->committed()));
             ok &= rpt->upsert_cstr(mm, "reserved", DInteger::box(mm, this->reserved()));
diff --git a/src/gc/facet/ICollector_DX1Collector.cpp b/src/gc/facet/ICollector_DX1Collector.cpp
index 2e3f55f..b07f169 100644
--- a/src/gc/facet/ICollector_DX1Collector.cpp
+++ b/src/gc/facet/ICollector_DX1Collector.cpp
@@ -33,6 +33,12 @@ namespace xo {
             return self.reserved(g, r);
         }
 
+        auto
+        ICollector_DX1Collector::locate_address(const DX1Collector & self, const void * addr) noexcept -> std::int32_t
+        {
+            return self.locate_address(addr);
+        }
+
         auto
         ICollector_DX1Collector::contains(const DX1Collector & self, role r, const void * addr) noexcept -> bool
         {