From 873e82a5329dffeeef9c91d0e47cf34c41c53b03 Mon Sep 17 00:00:00 2001
From: Samson <16504129+sagudev@users.noreply.github.com>
Date: Wed, 13 Nov 2024 07:50:30 +0100
Subject: [PATCH] Add `js.disable_jit` pref (#34231)

Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>
---
 components/config/prefs.rs | 2 ++
 components/script/init.rs  | 4 ++++
 resources/prefs.json       | 1 +
 3 files changed, 7 insertions(+)

diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index d3e37f25bd4..d525f7bf4fa 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -435,6 +435,8 @@ mod gen {
                 baseline_interpreter: {
                     enabled: bool,
                 },
+                /// Whether to disable the jit within SpiderMonkey
+                disable_jit: bool,
                 baseline_jit: {
                     enabled: bool,
                     unsafe_eager_compilation: {
diff --git a/components/script/init.rs b/components/script/init.rs
index badd36668bb..ec49c3f2953 100644
--- a/components/script/init.rs
+++ b/components/script/init.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use js::jsapi::JSObject;
+use servo_config::pref;
 
 use crate::dom::bindings::codegen::RegisterBindings;
 use crate::dom::bindings::conversions::is_dom_proxy;
@@ -61,6 +62,9 @@ unsafe extern "C" fn is_dom_object(obj: *mut JSObject) -> bool {
 #[allow(unsafe_code)]
 pub fn init() -> JSEngineSetup {
     unsafe {
+        if pref!(js.disable_jit) {
+            js::jsapi::DisableJitBackend();
+        }
         proxyhandler::init();
 
         // Create the global vtables used by the (generated) DOM
diff --git a/resources/prefs.json b/resources/prefs.json
index 4a763c8cd6f..e2b32d24449 100644
--- a/resources/prefs.json
+++ b/resources/prefs.json
@@ -61,6 +61,7 @@
   "js.baseline_interpreter.enabled": true,
   "js.baseline_jit.enabled": true,
   "js.baseline_jit.unsafe_eager_compilation.enabled": false,
+  "js.disable_jit": false,
   "js.discard_system_source.enabled": false,
   "js.dump_stack_on_debuggee_would_run.enabled": false,
   "js.ion.enabled": true,