From 596b1c1fde6b94326c7cc1ee35c81586fa04ab72 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 9 Mar 2025 15:49:44 +0000
Subject: Clear GC roots so valgrind can find leaks

---
 runtime/src/shed/gc.c                   | 15 ++++++++++++++-
 runtime/src/shed/gc.h                   |  5 +++++
 runtime/src/shed/gc/bump/gc.c           |  6 ++++++
 runtime/src/shed/gc/mark-and-sweep/gc.c |  7 +++++++
 4 files changed, 32 insertions(+), 1 deletion(-)

(limited to 'runtime/src')

diff --git a/runtime/src/shed/gc.c b/runtime/src/shed/gc.c
index b11b2bd7..dd31318d 100644
--- a/runtime/src/shed/gc.c
+++ b/runtime/src/shed/gc.c
@@ -18,7 +18,11 @@ bool shed__runtime__gc_is_gc_object(ShedObject object) {
 
 ShedGcRootIndex shed__runtime__gc_root_stack_index = 0;
 
-struct ShedGcObjectHeader* shed__runtime__gc_root_stack[16384];
+enum {
+    GC_ROOT_STACK_SIZE = 16384,
+};
+
+struct ShedGcObjectHeader* shed__runtime__gc_root_stack[GC_ROOT_STACK_SIZE];
 
 ShedGcRootIndex shed__runtime__gc_get_root_stack_index() {
     return shed__runtime__gc_root_stack_index;
@@ -40,3 +44,12 @@ void shed__runtime__gc_push_root(ShedObject gc_root) {
 
     shed__runtime__gc_push_root_gc_object((struct ShedGcObjectHeader*) gc_root);
 }
+
+// == Clearing ==
+
+void shed__runtime__gc_clear_roots(void) {
+    // Clearing all roots allows valgrind to detect leaks.
+    for (size_t gc_root_index = 0; gc_root_index < GC_ROOT_STACK_SIZE; gc_root_index++) {
+        shed__runtime__gc_root_stack[gc_root_index] = NULL;
+    }
+}
diff --git a/runtime/src/shed/gc.h b/runtime/src/shed/gc.h
index 70932148..8377e4cb 100644
--- a/runtime/src/shed/gc.h
+++ b/runtime/src/shed/gc.h
@@ -48,4 +48,9 @@ void* shed__runtime__gc_alloc(size_t size, uint32_t runtime_type_tag);
 
 void shed__runtime__gc_collect(void);
 
+// == Clearing ==
+
+void shed__runtime__gc_clear(void);
+void shed__runtime__gc_clear_roots(void);
+
 #endif
diff --git a/runtime/src/shed/gc/bump/gc.c b/runtime/src/shed/gc/bump/gc.c
index fe859dff..7cd9e199 100644
--- a/runtime/src/shed/gc/bump/gc.c
+++ b/runtime/src/shed/gc/bump/gc.c
@@ -44,3 +44,9 @@ void* shed__runtime__gc_alloc(size_t size, uint32_t runtime_type_tag) {
 
 void shed__runtime__gc_collect(void) {
 }
+
+// == Clearing ==
+
+void shed__runtime__gc_clear(void) {
+    shed__runtime__gc_clear_roots();
+}
diff --git a/runtime/src/shed/gc/mark-and-sweep/gc.c b/runtime/src/shed/gc/mark-and-sweep/gc.c
index 02759596..b9b6d7d8 100644
--- a/runtime/src/shed/gc/mark-and-sweep/gc.c
+++ b/runtime/src/shed/gc/mark-and-sweep/gc.c
@@ -104,3 +104,10 @@ void shed__runtime__gc_collect(void) {
 
     sweep();
 }
+
+// == Clearing ==
+
+void shed__runtime__gc_clear(void) {
+    first = NULL;
+    shed__runtime__gc_clear_roots();
+}
-- 
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