From 2c0bd763b48255b4c459c4c205a62899c94b5719 Mon Sep 17 00:00:00 2001
From: Sy Brand <sy.brand@fastly.com>
Date: Thu, 26 Mar 2026 14:00:07 +0000
Subject: [PATCH 1/3] Add --gc-frequency option

---
 runtime/fastly/CMakeLists.txt |  4 ++++
 runtime/fastly/build-debug.sh | 31 +++++++++++++++++++++++++++++--
 runtime/fastly/handler.cpp    |  3 +++
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/runtime/fastly/CMakeLists.txt b/runtime/fastly/CMakeLists.txt
index 8946db3dc6..05e68ee6c0 100644
--- a/runtime/fastly/CMakeLists.txt
+++ b/runtime/fastly/CMakeLists.txt
@@ -63,4 +63,8 @@ add_builtin(fastly::html_rewriter
 
 add_compile_definitions(PUBLIC RUNTIME_VERSION=${RUNTIME_VERSION})
 
+if(DEFINED FASTLY_GC_FREQUENCY)
+  add_compile_definitions(PUBLIC FASTLY_GC_FREQUENCY=${FASTLY_GC_FREQUENCY})
+endif()
+
 project(FastlyJS)
diff --git a/runtime/fastly/build-debug.sh b/runtime/fastly/build-debug.sh
index aa73879c15..9aedb2dd18 100755
--- a/runtime/fastly/build-debug.sh
+++ b/runtime/fastly/build-debug.sh
@@ -4,10 +4,37 @@ set -euo pipefail
 set -x
 
 cd "$(dirname "$0")" || exit 1
+
+# Parse command line arguments
+KEEP_DEBUG_INFO=0
+GC_FREQUENCY=""
+
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    --keep-debug-info)
+      KEEP_DEBUG_INFO=1
+      shift
+      ;;
+    --gc-frequency)
+      if [[ -n "${2:-}" ]]; then
+        GC_FREQUENCY="-DFASTLY_GC_FREQUENCY=$2"
+        shift 2
+      else
+        echo "Error: --gc-frequency requires a value"
+        exit 1
+      fi
+      ;;
+    *)
+      echo "Unknown option: $1"
+      exit 1
+      ;;
+  esac
+done
+
 RUNTIME_VERSION=$(npm pkg get version --json --prefix=../../ | jq -r)
-HOST_API=$(realpath host-api) cmake -B build-debug -DCMAKE_BUILD_TYPE=Debug -DENABLE_BUILTIN_WEB_FETCH=0 -DENABLE_BUILTIN_WEB_FETCH_FETCH_EVENT=0 -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DRUNTIME_VERSION="\"$RUNTIME_VERSION-debug\"" -DENABLE_JS_DEBUGGER=OFF
+HOST_API=$(realpath host-api) cmake -B build-debug -DCMAKE_BUILD_TYPE=Debug -DENABLE_BUILTIN_WEB_FETCH=0 -DENABLE_BUILTIN_WEB_FETCH_FETCH_EVENT=0 -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DRUNTIME_VERSION="\"$RUNTIME_VERSION-debug\"" -DENABLE_JS_DEBUGGER=OFF $GC_FREQUENCY
 cmake --build build-debug --parallel 10
-if [ "${1:-default}" != "--keep-debug-info" ]; then
+if [ "$KEEP_DEBUG_INFO" -eq 0 ]; then
   wasm-tools strip build-debug/starling-raw.wasm/starling-raw.wasm -d ".debug_(info|loc|ranges|abbrev|line|str)" -o ../../fastly.debug.wasm
 else
   cp build-debug/starling-raw.wasm/starling-raw.wasm ../../fastly.debug.wasm
diff --git a/runtime/fastly/handler.cpp b/runtime/fastly/handler.cpp
index dd722d1a79..bc7d807d4d 100644
--- a/runtime/fastly/handler.cpp
+++ b/runtime/fastly/handler.cpp
@@ -19,6 +19,9 @@ api::Engine *ENGINE;
 
 // Install corresponds to Wizer time, so we configure the engine here
 bool install(api::Engine *engine) {
+  #if defined(JS_GC_ZEAL) && defined(FASTLY_GC_FREQUENCY)
+  JS::SetGCZeal(engine->cx(), 2, FASTLY_GC_FREQUENCY);
+  #endif
   ENGINE = engine;
   return true;
 }

From 6f1729b58250e15f03641b1904c00c83a4d0c5d9 Mon Sep 17 00:00:00 2001
From: Sy Brand <sy.brand@fastly.com>
Date: Thu, 26 Mar 2026 14:09:39 +0000
Subject: [PATCH 2/3] fmt

---
 runtime/fastly/handler.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/runtime/fastly/handler.cpp b/runtime/fastly/handler.cpp
index bc7d807d4d..a962876fc7 100644
--- a/runtime/fastly/handler.cpp
+++ b/runtime/fastly/handler.cpp
@@ -19,9 +19,9 @@ api::Engine *ENGINE;
 
 // Install corresponds to Wizer time, so we configure the engine here
 bool install(api::Engine *engine) {
-  #if defined(JS_GC_ZEAL) && defined(FASTLY_GC_FREQUENCY)
+#if defined(JS_GC_ZEAL) && defined(FASTLY_GC_FREQUENCY)
   JS::SetGCZeal(engine->cx(), 2, FASTLY_GC_FREQUENCY);
-  #endif
+#endif
   ENGINE = engine;
   return true;
 }

From f8d0e969fb135daf329f00f247c87a91f39967f9 Mon Sep 17 00:00:00 2001
From: Sy Brand <sy.brand@fastly.com>
Date: Thu, 26 Mar 2026 14:19:22 +0000
Subject: [PATCH 3/3] Shellcheck

---
 runtime/fastly/build-debug.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/runtime/fastly/build-debug.sh b/runtime/fastly/build-debug.sh
index 9aedb2dd18..5968694f1a 100755
--- a/runtime/fastly/build-debug.sh
+++ b/runtime/fastly/build-debug.sh
@@ -32,7 +32,7 @@ while [[ $# -gt 0 ]]; do
 done
 
 RUNTIME_VERSION=$(npm pkg get version --json --prefix=../../ | jq -r)
-HOST_API=$(realpath host-api) cmake -B build-debug -DCMAKE_BUILD_TYPE=Debug -DENABLE_BUILTIN_WEB_FETCH=0 -DENABLE_BUILTIN_WEB_FETCH_FETCH_EVENT=0 -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DRUNTIME_VERSION="\"$RUNTIME_VERSION-debug\"" -DENABLE_JS_DEBUGGER=OFF $GC_FREQUENCY
+HOST_API=$(realpath host-api) cmake -B build-debug -DCMAKE_BUILD_TYPE=Debug -DENABLE_BUILTIN_WEB_FETCH=0 -DENABLE_BUILTIN_WEB_FETCH_FETCH_EVENT=0 -DCMAKE_EXPORT_COMPILE_COMMANDS=1 -DRUNTIME_VERSION="\"$RUNTIME_VERSION-debug\"" -DENABLE_JS_DEBUGGER=OFF "$GC_FREQUENCY"
 cmake --build build-debug --parallel 10
 if [ "$KEEP_DEBUG_INFO" -eq 0 ]; then
   wasm-tools strip build-debug/starling-raw.wasm/starling-raw.wasm -d ".debug_(info|loc|ranges|abbrev|line|str)" -o ../../fastly.debug.wasm