From 80f090056515d8bb29be1f9bd1f005a4e8ec84a9 Mon Sep 17 00:00:00 2001
From: Jonne Ransijn <jonne@yyny.dev>
Date: Thu, 31 Oct 2024 22:46:44 +0100
Subject: [PATCH] LibJS: Share argument values buffer between calls

This buffer is being created and then immediately destroyed,
let's reuse it to reduce memory allocations.
---
 Userland/Libraries/LibJS/Bytecode/Interpreter.cpp | 5 ++---
 Userland/Libraries/LibJS/Bytecode/Interpreter.h   | 6 ++++++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
index 824ca3b6fa0..5495d5b5dc5 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -2545,10 +2545,9 @@ ThrowCompletionOr<void> Call::execute_impl(Bytecode::Interpreter& interpreter) c
         return {};
     }
 
-    Vector<Value> argument_values;
-    argument_values.ensure_capacity(m_argument_count);
+    auto argument_values = interpreter.allocate_argument_values(m_argument_count);
     for (size_t i = 0; i < m_argument_count; ++i)
-        argument_values.unchecked_append(interpreter.get(m_arguments[i]));
+        argument_values[i] = interpreter.get(m_arguments[i]);
     interpreter.set(dst(), TRY(perform_call(interpreter, interpreter.get(m_this_value), call_type(), callee, argument_values)));
     return {};
 }
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.h b/Userland/Libraries/LibJS/Bytecode/Interpreter.h
index 1da7aa77cb4..98d6598ce01 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.h
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.h
@@ -77,6 +77,11 @@ public:
     Executable& current_executable() { return *m_current_executable; }
     Executable const& current_executable() const { return *m_current_executable; }
     Optional<size_t> program_counter() const { return m_program_counter; }
+    Span<Value> allocate_argument_values(size_t argument_count)
+    {
+        m_argument_values_buffer.resize_and_keep_capacity(argument_count);
+        return m_argument_values_buffer.span();
+    }
 
     ExecutionContext& running_execution_context() { return *m_running_execution_context; }
 
@@ -98,6 +103,7 @@ private:
     Optional<size_t&> m_program_counter;
     Span<Value> m_arguments;
     Span<Value> m_registers_and_constants_and_locals;
+    Vector<Value> m_argument_values_buffer;
     ExecutionContext* m_running_execution_context { nullptr };
 };