From 3ba6d129df607b3f114e9e61259611f9883412e2 Mon Sep 17 00:00:00 2001
From: Julien Le Bras <julien.lb.pro@gmail.com>
Date: Sat, 24 May 2025 15:28:46 +0200
Subject: [PATCH] LibJS: Cache string constants in Generator::add_constant

This mirrors the existing caching logic for int32 constants.
Avoids duplication of string constants in m_constants which could
result in stack overflows for large scripts with a lot of similar
strings.
---
 Libraries/LibJS/Bytecode/Generator.cpp | 6 ++++++
 Libraries/LibJS/Bytecode/Generator.h   | 1 +
 2 files changed, 7 insertions(+)

diff --git a/Libraries/LibJS/Bytecode/Generator.cpp b/Libraries/LibJS/Bytecode/Generator.cpp
index dd07edb60eb..5fb900aa101 100644
--- a/Libraries/LibJS/Bytecode/Generator.cpp
+++ b/Libraries/LibJS/Bytecode/Generator.cpp
@@ -1344,6 +1344,12 @@ ScopedOperand Generator::add_constant(Value value)
             return append_new_constant();
         });
     }
+    if (value.is_string()) {
+        auto as_string = value.as_string().utf8_string();
+        return m_string_constants.ensure(as_string, [&] {
+            return append_new_constant();
+        });
+    }
     return append_new_constant();
 }
 
diff --git a/Libraries/LibJS/Bytecode/Generator.h b/Libraries/LibJS/Bytecode/Generator.h
index 980375a589d..e0cb070ac7d 100644
--- a/Libraries/LibJS/Bytecode/Generator.h
+++ b/Libraries/LibJS/Bytecode/Generator.h
@@ -397,6 +397,7 @@ private:
     mutable Optional<ScopedOperand> m_undefined_constant;
     mutable Optional<ScopedOperand> m_empty_constant;
     mutable HashMap<i32, ScopedOperand> m_int32_constants;
+    mutable HashMap<String, ScopedOperand> m_string_constants;
 
     ScopedOperand m_accumulator;
     ScopedOperand m_this_value;