From 5b9469786e0eb6d5594af8ad0082981fe56aaeca Mon Sep 17 00:00:00 2001
From: Andreas Kling <andreas@ladybird.org>
Date: Fri, 31 Oct 2025 21:26:12 +0100
Subject: [PATCH] LibJS: Move ExecutionContext::cached_source_range to rare
 data

---
 Libraries/LibJS/Runtime/ExecutionContext.cpp |  2 +-
 Libraries/LibJS/Runtime/ExecutionContext.h   |  4 ++--
 Libraries/LibJS/Runtime/VM.cpp               | 11 ++++++-----
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/Libraries/LibJS/Runtime/ExecutionContext.cpp b/Libraries/LibJS/Runtime/ExecutionContext.cpp
index 39bcd3b6a7..bceee6b598 100644
--- a/Libraries/LibJS/Runtime/ExecutionContext.cpp
+++ b/Libraries/LibJS/Runtime/ExecutionContext.cpp
@@ -144,7 +144,6 @@ void ExecutionContext::visit_edges(Cell::Visitor& visitor)
     visitor.visit(variable_environment);
     visitor.visit(lexical_environment);
     visitor.visit(private_environment);
-    visitor.visit(cached_source_range);
     visitor.visit(m_rare_data);
     if (this_value.has_value())
         visitor.visit(*this_value);
@@ -161,6 +160,7 @@ void ExecutionContextRareData::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);
     visitor.visit(context_owner);
+    visitor.visit(cached_source_range);
     for (auto& context : unwind_contexts) {
         visitor.visit(context.lexical_environment);
     }
diff --git a/Libraries/LibJS/Runtime/ExecutionContext.h b/Libraries/LibJS/Runtime/ExecutionContext.h
index fec8d446b8..9abc4e0577 100644
--- a/Libraries/LibJS/Runtime/ExecutionContext.h
+++ b/Libraries/LibJS/Runtime/ExecutionContext.h
@@ -45,6 +45,8 @@ public:
     Vector<Optional<size_t>> previously_scheduled_jumps;
     Vector<GC::Ptr<Environment>> saved_lexical_environments;
 
+    mutable GC::Ptr<CachedSourceRange> cached_source_range;
+
     // Non-standard: This points at something that owns this ExecutionContext, in case it needs to be protected from GC.
     GC::Ptr<Cell> context_owner;
 
@@ -90,8 +92,6 @@ public:
     // FIXME: Move this out of LibJS (e.g. by using the CustomData concept), as it's used exclusively by LibWeb.
     u32 skip_when_determining_incumbent_counter { 0 };
 
-    mutable GC::Ptr<CachedSourceRange> cached_source_range;
-
     Optional<Value> this_value;
 
     GC::Ptr<Bytecode::Executable> executable;
diff --git a/Libraries/LibJS/Runtime/VM.cpp b/Libraries/LibJS/Runtime/VM.cpp
index 72de4fb281..81dd09e4d9 100644
--- a/Libraries/LibJS/Runtime/VM.cpp
+++ b/Libraries/LibJS/Runtime/VM.cpp
@@ -753,20 +753,21 @@ void VM::load_imported_module(ImportedModuleReferrer referrer, ModuleRequest con
     finish_loading_imported_module(referrer, module_request, payload, module);
 }
 
-static GC::Ptr<CachedSourceRange> get_source_range(ExecutionContext const* context)
+static GC::Ptr<CachedSourceRange> get_source_range(ExecutionContext* context)
 {
     // native function
     if (!context->executable)
         return {};
 
-    if (!context->cached_source_range
-        || context->cached_source_range->program_counter != context->program_counter) {
+    if (!context->rare_data()
+        || !context->rare_data()->cached_source_range
+        || context->rare_data()->cached_source_range->program_counter != context->program_counter) {
         auto unrealized_source_range = context->executable->source_range_at(context->program_counter);
-        context->cached_source_range = context->executable->heap().allocate<CachedSourceRange>(
+        context->ensure_rare_data()->cached_source_range = context->executable->heap().allocate<CachedSourceRange>(
             context->program_counter,
             move(unrealized_source_range));
     }
-    return context->cached_source_range;
+    return context->rare_data()->cached_source_range;
 }
 
 Vector<StackTraceElement> VM::stack_trace() const