From decc2211097305383554cb1544d0f6d05e8a3b36 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 20 Oct 2023 13:04:51 +0200
Subject: [PATCH] LibJS/JIT: Save and restore callee-saved registers in jitted
 code

---
 Userland/Libraries/LibJS/JIT/Assembler.h | 27 ++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/Userland/Libraries/LibJS/JIT/Assembler.h b/Userland/Libraries/LibJS/JIT/Assembler.h
index 9b9e111388..b67c364d27 100644
--- a/Userland/Libraries/LibJS/JIT/Assembler.h
+++ b/Userland/Libraries/LibJS/JIT/Assembler.h
@@ -311,6 +311,8 @@ struct Assembler {
 
     void enter()
     {
+        push_callee_saved_registers();
+
         push(Operand::Register(Reg::RBP));
         mov(Operand::Register(Reg::RBP), Operand::Register(Reg::RSP));
         sub(Operand::Register(Reg::RSP), Operand::Imm8(8));
@@ -321,10 +323,35 @@ struct Assembler {
         // leave
         emit8(0xc9);
 
+        pop_callee_saved_registers();
+
         // ret
         emit8(0xc3);
     }
 
+    void push_callee_saved_registers()
+    {
+        // FIXME: Don't push RBX twice :^)
+        push(Operand::Register(Reg::RBX));
+        push(Operand::Register(Reg::RBX));
+        push(Operand::Register(Reg::R12));
+        push(Operand::Register(Reg::R13));
+        push(Operand::Register(Reg::R14));
+        push(Operand::Register(Reg::R15));
+    }
+
+    void pop_callee_saved_registers()
+    {
+        pop(Operand::Register(Reg::R15));
+        pop(Operand::Register(Reg::R14));
+        pop(Operand::Register(Reg::R13));
+        pop(Operand::Register(Reg::R12));
+
+        // FIXME: Don't pop RBX twice :^)
+        pop(Operand::Register(Reg::RBX));
+        pop(Operand::Register(Reg::RBX));
+    }
+
     void push(Operand op)
     {
         if (op.type == Operand::Type::Reg) {