From fc9180363d1a57510b190ca9bf85c118b284c2a1 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Wed, 6 Aug 2025 09:30:37 -0500
Subject: [PATCH] xo-object: generative GC utest + reinstate coverage build

---
 include/xo/alloc/GC.hpp   |  1 +
 src/alloc/ArenaAlloc.cpp  | 11 ++++++-----
 src/alloc/Forwarding1.cpp |  6 ++++++
 src/alloc/GC.cpp          | 19 ++++++++++++++++++-
 src/alloc/IAlloc.cpp      |  2 ++
 utest/CMakeLists.txt      |  1 +
 6 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/include/xo/alloc/GC.hpp b/include/xo/alloc/GC.hpp
index 0c50a722..6f9573f3 100644
--- a/include/xo/alloc/GC.hpp
+++ b/include/xo/alloc/GC.hpp
@@ -218,6 +218,7 @@ namespace xo {
         public:
             /** create new GC instance with configuration @p config **/
             explicit GC(const Config & config);
+            virtual ~GC();
 
             /** create GC allocator.
              *
diff --git a/src/alloc/ArenaAlloc.cpp b/src/alloc/ArenaAlloc.cpp
index 227e2d63..c3f70d8c 100644
--- a/src/alloc/ArenaAlloc.cpp
+++ b/src/alloc/ArenaAlloc.cpp
@@ -56,6 +56,8 @@ namespace xo {
 
             if (lo_ <= x && x < limit_) {
                 this->free_ptr_ = x;
+                if (this->checkpoint_ > free_ptr_)
+                    this->checkpoint_ = free_ptr_;
             } else {
                 throw std::runtime_error(tostr("LinearAllog::set_free_ptr(x): expected lo <= x < limit",
                                                xtag("lo", lo_), xtag("x", x), xtag("limit", limit_)));
@@ -102,8 +104,7 @@ namespace xo {
         void
         ArenaAlloc::clear()
         {
-            this->checkpoint_ = lo_;
-            this->free_ptr_ = lo_;
+            this->set_free_ptr(lo_);
             this->limit_ = hi_ - redline_z_;
         }
 
@@ -133,14 +134,14 @@ namespace xo {
 
             std::byte * retval = this->free_ptr_;
 
-            this->free_ptr_ += z1;
-
             log && log(xtag("self", name_), xtag("z0", z0), xtag("+pad", dz), xtag("z1", z1));
 
-            if (free_ptr_ > limit_) {
+            if (free_ptr_ + z1 > limit_) {
                 return nullptr;
             }
 
+            this->free_ptr_ += z1;
+
             return retval;
         }
 
diff --git a/src/alloc/Forwarding1.cpp b/src/alloc/Forwarding1.cpp
index ca4f051b..32d95b60 100644
--- a/src/alloc/Forwarding1.cpp
+++ b/src/alloc/Forwarding1.cpp
@@ -26,23 +26,29 @@ namespace xo {
             return dest_.ptr();
         }
 
+        // LCOV_EXCL_START
         std::size_t
         Forwarding1::_shallow_size() const {
             assert(false);
             return 0;
         }
+        // LCOV_EXCL_STOP
 
+        // LCOV_EXCL_START
         Object *
         Forwarding1::_shallow_copy() const {
             assert(false);
             return nullptr;
         }
+        // LCOV_EXCL_STOP
 
+        // LCOV_EXCL_START
         std::size_t
         Forwarding1::_forward_children() {
             assert(false);
             return 0;
         }
+        // LCOV_EXCL_STOP
 
     } /*namespace obj*/
 } /*namespace xo*/
diff --git a/src/alloc/GC.cpp b/src/alloc/GC.cpp
index 6dd8a929..4f106779 100644
--- a/src/alloc/GC.cpp
+++ b/src/alloc/GC.cpp
@@ -141,6 +141,21 @@ namespace xo {
             this->checkpoint();
         }
 
+        GC::~GC() {
+            /* hygiene */
+            this->clear();
+
+            nursery_[role2int(role::from_space)].reset();
+            nursery_[role2int(role::to_space)  ].reset();
+
+            tenured_[role2int(role::from_space)].reset();
+            tenured_[role2int(role::to_space)  ].reset();
+
+            mutation_log_[role2int(role::from_space)].reset();
+            mutation_log_[role2int(role::to_space)  ].reset();
+            defer_mutation_log_.reset();
+        }
+
         up<GC>
         GC::make(const Config & config)
         {
@@ -245,8 +260,10 @@ namespace xo {
                 return nursery_[role2int(role::to_space)]->free_ptr();
             case generation::tenured:
                 return tenured_[role2int(role::to_space)]->free_ptr();
+                // LCOV_EXCL_START
             case generation::N:
                 assert(false);
+                // LCOV_EXCL_STOP
             }
 
             return nullptr;
@@ -647,7 +664,7 @@ namespace xo {
 
                     Object * parent_to = from_entry.parent_destination();
 
-                    log(xtag("parent_to", (void*)parent_to));
+                    log && log(xtag("parent_to", (void*)parent_to));
 
                     assert(tospace_generation_of(parent_to) == generation_result::tenured);
 
diff --git a/src/alloc/IAlloc.cpp b/src/alloc/IAlloc.cpp
index 6e06a644..8fe4789a 100644
--- a/src/alloc/IAlloc.cpp
+++ b/src/alloc/IAlloc.cpp
@@ -47,12 +47,14 @@ namespace xo {
             *lhs = rhs;
         }
 
+        // LCOV_EXCL_START
         std::byte *
         IAlloc::alloc_gc_copy(std::size_t /*z*/, const void * /*src*/)
         {
             assert(false);
             return nullptr;
         }
+        // LCOV_EXCL_STOP
 
     } /*namespace gc*/
 } /*namespace xo*/
diff --git a/utest/CMakeLists.txt b/utest/CMakeLists.txt
index 50882bba..b38a442f 100644
--- a/utest/CMakeLists.txt
+++ b/utest/CMakeLists.txt
@@ -5,6 +5,7 @@
 set(UTEST_EXE utest.alloc)
 set(UTEST_SRCS
     alloc_utest_main.cpp
+    IAlloc.test.cpp
     ArenaAlloc.test.cpp
     GC.test.cpp)