From 2b9fbd10ed7cec26aafae01fee803bce23b83b27 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 3 Jun 2021 18:32:33 +0200
Subject: [PATCH] LibJS: Add Sub bytecode instruction (subtract values)

---
 Userland/Libraries/LibJS/AST.cpp         |  9 ++++++---
 Userland/Libraries/LibJS/Bytecode/Op.cpp | 10 ++++++++++
 Userland/Libraries/LibJS/Bytecode/Op.h   | 19 +++++++++++++++++++
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index fdd9bc60d0e..505cc5f8c11 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -2264,12 +2264,15 @@ Optional<Bytecode::Register> BinaryExpression::generate_bytecode(Bytecode::Gener
     VERIFY(lhs_reg.has_value());
     VERIFY(rhs_reg.has_value());
 
+    auto dst_reg = generator.allocate_register();
+
     switch (m_op) {
-    case BinaryOp::Addition: {
-        auto dst_reg = generator.allocate_register();
+    case BinaryOp::Addition:
         generator.emit<Bytecode::Op::Add>(dst_reg, *lhs_reg, *rhs_reg);
         return dst_reg;
-    }
+    case BinaryOp::Subtraction:
+        generator.emit<Bytecode::Op::Sub>(dst_reg, *lhs_reg, *rhs_reg);
+        return dst_reg;
     default:
         TODO();
     }
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.cpp b/Userland/Libraries/LibJS/Bytecode/Op.cpp
index b1feea00e4e..570bcff1122 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Op.cpp
@@ -21,6 +21,11 @@ void Add::execute(Bytecode::Interpreter& interpreter) const
     interpreter.reg(m_dst) = add(interpreter.global_object(), interpreter.reg(m_src1), interpreter.reg(m_src2));
 }
 
+void Sub::execute(Bytecode::Interpreter& interpreter) const
+{
+    interpreter.reg(m_dst) = sub(interpreter.global_object(), interpreter.reg(m_src1), interpreter.reg(m_src2));
+}
+
 void NewString::execute(Bytecode::Interpreter& interpreter) const
 {
     interpreter.reg(m_dst) = js_string(interpreter.vm(), m_string);
@@ -46,6 +51,11 @@ String Add::to_string() const
     return String::formatted("Add dst:{}, src1:{}, src2:{}", m_dst, m_src1, m_src2);
 }
 
+String Sub::to_string() const
+{
+    return String::formatted("Sub dst:{}, src1:{}, src2:{}", m_dst, m_src1, m_src2);
+}
+
 String NewString::to_string() const
 {
     return String::formatted("NewString dst:{}, string:\"{}\"", m_dst, m_string);
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.h b/Userland/Libraries/LibJS/Bytecode/Op.h
index 77f46f2a762..93fc9514834 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.h
+++ b/Userland/Libraries/LibJS/Bytecode/Op.h
@@ -50,6 +50,25 @@ private:
     Register m_src2;
 };
 
+class Sub final : public Instruction {
+public:
+    Sub(Register dst, Register src1, Register src2)
+        : m_dst(dst)
+        , m_src1(src1)
+        , m_src2(src2)
+    {
+    }
+
+    virtual ~Sub() override { }
+    virtual void execute(Bytecode::Interpreter&) const override;
+    virtual String to_string() const override;
+
+private:
+    Register m_dst;
+    Register m_src1;
+    Register m_src2;
+};
+
 class NewString final : public Instruction {
 public:
     NewString(Register dst, String string)