From caffd485b8bbd27547fbb07d958d0663b7610d31 Mon Sep 17 00:00:00 2001
From: Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
Date: Tue, 14 May 2024 04:40:47 +0200
Subject: [PATCH] LibJS: Replace SetLocal instruction usage with Mov

No need for separate instuction to set a local.
---
 .../Libraries/LibJS/Bytecode/Generator.cpp    |  2 +-
 .../Libraries/LibJS/Bytecode/Instruction.h    |  1 -
 .../Libraries/LibJS/Bytecode/Interpreter.cpp  | 20 --------------
 Userland/Libraries/LibJS/Bytecode/Op.h        | 26 -------------------
 4 files changed, 1 insertion(+), 48 deletions(-)

diff --git a/Userland/Libraries/LibJS/Bytecode/Generator.cpp b/Userland/Libraries/LibJS/Bytecode/Generator.cpp
index 75b1a2ffba..513e9ab477 100644
--- a/Userland/Libraries/LibJS/Bytecode/Generator.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Generator.cpp
@@ -814,7 +814,7 @@ void Generator::emit_set_variable(JS::Identifier const& identifier, ScopedOperan
             // Moving a local to itself is a no-op.
             return;
         }
-        emit<Bytecode::Op::SetLocal>(identifier.local_variable_index(), value);
+        emit<Bytecode::Op::Mov>(local(identifier.local_variable_index()), value);
     } else {
         emit<Bytecode::Op::SetVariable>(intern_identifier(identifier.string()), value, initialization_mode, mode);
     }
diff --git a/Userland/Libraries/LibJS/Bytecode/Instruction.h b/Userland/Libraries/LibJS/Bytecode/Instruction.h
index 2999f164bb..199eededf7 100644
--- a/Userland/Libraries/LibJS/Bytecode/Instruction.h
+++ b/Userland/Libraries/LibJS/Bytecode/Instruction.h
@@ -123,7 +123,6 @@
     O(ScheduleJump)                    \
     O(SetArgument)                     \
     O(SetVariable)                     \
-    O(SetLocal)                        \
     O(StrictlyEquals)                  \
     O(StrictlyInequals)                \
     O(Sub)                             \
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
index c0e01a5756..9de1d768bd 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -328,7 +328,6 @@ FLATTEN_ON_CLANG void Interpreter::run_bytecode(size_t entry_point)
 
     auto& running_execution_context = this->running_execution_context();
     auto* arguments = running_execution_context.arguments.data();
-    auto* registers_and_constants_and_locals = running_execution_context.registers_and_constants_and_locals.data();
     auto& accumulator = this->accumulator();
     auto& executable = current_executable();
     auto const* bytecode = executable.bytecode.data();
@@ -364,12 +363,6 @@ FLATTEN_ON_CLANG void Interpreter::run_bytecode(size_t entry_point)
         for (;;) {
             goto* bytecode_dispatch_table[static_cast<size_t>((*reinterpret_cast<Instruction const*>(&bytecode[program_counter])).type())];
 
-        handle_SetLocal: {
-            auto& instruction = *reinterpret_cast<Op::SetLocal const*>(&bytecode[program_counter]);
-            registers_and_constants_and_locals[instruction.index()] = get(instruction.src());
-            DISPATCH_NEXT(SetLocal);
-        }
-
         handle_GetArgument: {
             auto const& instruction = *reinterpret_cast<Op::GetArgument const*>(&bytecode[program_counter]);
             set(instruction.dst(), arguments[instruction.index()]);
@@ -1396,12 +1389,6 @@ ThrowCompletionOr<void> SetVariable::execute_impl(Bytecode::Interpreter& interpr
     return {};
 }
 
-ThrowCompletionOr<void> SetLocal::execute_impl(Bytecode::Interpreter&) const
-{
-    // Handled in the interpreter loop.
-    __builtin_unreachable();
-}
-
 ThrowCompletionOr<void> SetArgument::execute_impl(Bytecode::Interpreter&) const
 {
     // Handled in the interpreter loop.
@@ -2156,13 +2143,6 @@ ByteString SetVariable::to_byte_string_impl(Bytecode::Executable const& executab
         mode_string, initialization_mode_name);
 }
 
-ByteString SetLocal::to_byte_string_impl(Bytecode::Executable const& executable) const
-{
-    return ByteString::formatted("SetLocal {}, {}",
-        format_operand("dst"sv, dst(), executable),
-        format_operand("src"sv, src(), executable));
-}
-
 ByteString GetArgument::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     return ByteString::formatted("GetArgument {}, {}", index(), format_operand("dst"sv, dst(), executable));
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.h b/Userland/Libraries/LibJS/Bytecode/Op.h
index 485f0e75bf..d3b941d177 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.h
+++ b/Userland/Libraries/LibJS/Bytecode/Op.h
@@ -699,32 +699,6 @@ private:
     mutable EnvironmentCoordinate m_cache;
 };
 
-class SetLocal final : public Instruction {
-public:
-    SetLocal(size_t index, Operand src)
-        : Instruction(Type::SetLocal)
-        , m_dst(Operand(Operand::Type::Local, index))
-        , m_src(src)
-    {
-    }
-
-    ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
-    void visit_operands_impl(Function<void(Operand&)> visitor)
-    {
-        visitor(m_dst);
-        visitor(m_src);
-    }
-
-    u32 index() const { return m_dst.index(); }
-    Operand dst() const { return m_dst; }
-    Operand src() const { return m_src; }
-
-private:
-    Operand m_dst;
-    Operand m_src;
-};
-
 class SetArgument final : public Instruction {
 public:
     SetArgument(size_t index, Operand src)