From 089d10695a74619e66f8b1f866412dcae6cdbc1d Mon Sep 17 00:00:00 2001
From: Haled Odat <8566042+HalidOdat@users.noreply.github.com>
Date: Wed, 12 Jul 2023 15:16:43 +0200
Subject: [PATCH] Remove LoopStart opcode

---
 boa_engine/src/bytecompiler/statement/loop.rs   |  3 ---
 boa_engine/src/bytecompiler/statement/switch.rs |  2 --
 boa_engine/src/vm/code_block.rs                 |  4 ++--
 boa_engine/src/vm/flowgraph/mod.rs              |  4 ++--
 boa_engine/src/vm/opcode/iteration/loop_ops.rs  | 17 -----------------
 boa_engine/src/vm/opcode/mod.rs                 |  7 ++-----
 6 files changed, 6 insertions(+), 31 deletions(-)

diff --git a/boa_engine/src/bytecompiler/statement/loop.rs b/boa_engine/src/bytecompiler/statement/loop.rs
index 381cb023906..7438db829ec 100644
--- a/boa_engine/src/bytecompiler/statement/loop.rs
+++ b/boa_engine/src/bytecompiler/statement/loop.rs
@@ -57,7 +57,6 @@ impl ByteCompiler<'_, '_> {
         }
 
         self.push_empty_loop_jump_control(use_expr);
-        self.emit_opcode(Opcode::LoopStart);
         let initial_jump = self.jump();
         let start_address = self.next_opcode_location();
 
@@ -415,7 +414,6 @@ impl ByteCompiler<'_, '_> {
         label: Option<Sym>,
         use_expr: bool,
     ) {
-        self.emit_opcode(Opcode::LoopStart);
         let start_address = self.next_opcode_location();
         self.emit_opcode(Opcode::LoopContinue);
         self.push_loop_control_info(label, start_address, use_expr);
@@ -437,7 +435,6 @@ impl ByteCompiler<'_, '_> {
         label: Option<Sym>,
         use_expr: bool,
     ) {
-        self.emit_opcode(Opcode::LoopStart);
         let initial_label = self.jump();
 
         let start_address = self.next_opcode_location();
diff --git a/boa_engine/src/bytecompiler/statement/switch.rs b/boa_engine/src/bytecompiler/statement/switch.rs
index 6fd0ccaf3cd..46df6c692f9 100644
--- a/boa_engine/src/bytecompiler/statement/switch.rs
+++ b/boa_engine/src/bytecompiler/statement/switch.rs
@@ -11,8 +11,6 @@ impl ByteCompiler<'_, '_> {
 
         self.block_declaration_instantiation(switch);
 
-        self.emit_opcode(Opcode::LoopStart);
-
         let start_address = self.next_opcode_location();
         self.push_switch_control_info(None, start_address, use_expr);
 
diff --git a/boa_engine/src/vm/code_block.rs b/boa_engine/src/vm/code_block.rs
index 34f177a1651..ddce1edcb4a 100644
--- a/boa_engine/src/vm/code_block.rs
+++ b/boa_engine/src/vm/code_block.rs
@@ -544,7 +544,6 @@ impl CodeBlock {
             | Opcode::Return
             | Opcode::PopEnvironment
             | Opcode::LoopContinue
-            | Opcode::LoopStart
             | Opcode::CreateForInIterator
             | Opcode::GetIterator
             | Opcode::GetAsyncIterator
@@ -651,7 +650,8 @@ impl CodeBlock {
             | Opcode::Reserved58
             | Opcode::Reserved59
             | Opcode::Reserved60
-            | Opcode::Reserved61 => unreachable!("Reserved opcodes are unrechable"),
+            | Opcode::Reserved61
+            | Opcode::Reserved62 => unreachable!("Reserved opcodes are unrechable"),
         }
     }
 }
diff --git a/boa_engine/src/vm/flowgraph/mod.rs b/boa_engine/src/vm/flowgraph/mod.rs
index 4913ca2a931..bbbb3c7c2b2 100644
--- a/boa_engine/src/vm/flowgraph/mod.rs
+++ b/boa_engine/src/vm/flowgraph/mod.rs
@@ -546,7 +546,6 @@ impl CodeBlock {
                 | Opcode::This
                 | Opcode::Super
                 | Opcode::LoopContinue
-                | Opcode::LoopStart
                 | Opcode::CreateForInIterator
                 | Opcode::GetIterator
                 | Opcode::GetAsyncIterator
@@ -672,7 +671,8 @@ impl CodeBlock {
                 | Opcode::Reserved58
                 | Opcode::Reserved59
                 | Opcode::Reserved60
-                | Opcode::Reserved61 => unreachable!("Reserved opcodes are unrechable"),
+                | Opcode::Reserved61
+                | Opcode::Reserved62 => unreachable!("Reserved opcodes are unrechable"),
             }
         }
 
diff --git a/boa_engine/src/vm/opcode/iteration/loop_ops.rs b/boa_engine/src/vm/opcode/iteration/loop_ops.rs
index bf210637ff4..d2b248268cf 100644
--- a/boa_engine/src/vm/opcode/iteration/loop_ops.rs
+++ b/boa_engine/src/vm/opcode/iteration/loop_ops.rs
@@ -4,22 +4,6 @@ use crate::{
     Context, JsResult,
 };
 
-/// `LoopStart` implements the Opcode Operation for `Opcode::LoopStart`
-///
-/// Operation:
-///  - Push loop start marker.
-#[derive(Debug, Clone, Copy)]
-pub(crate) struct LoopStart;
-
-impl Operation for LoopStart {
-    const NAME: &'static str = "LoopStart";
-    const INSTRUCTION: &'static str = "INST - LoopStart";
-
-    fn execute(_context: &mut Context<'_>) -> JsResult<CompletionType> {
-        Ok(CompletionType::Normal)
-    }
-}
-
 /// `LoopContinue` implements the Opcode Operation for `Opcode::LoopContinue`.
 ///
 /// Operation:
@@ -42,7 +26,6 @@ impl Operation for LoopContinue {
         }
 
         context.vm.frame_mut().loop_iteration_count = previous_iteration_count.wrapping_add(1);
-
         Ok(CompletionType::Normal)
     }
 }
diff --git a/boa_engine/src/vm/opcode/mod.rs b/boa_engine/src/vm/opcode/mod.rs
index 717e4239e14..6adb27b0615 100644
--- a/boa_engine/src/vm/opcode/mod.rs
+++ b/boa_engine/src/vm/opcode/mod.rs
@@ -1356,11 +1356,6 @@ generate_impl! {
         /// Stack: **=>**
         PopEnvironment,
 
-        /// Loop start marker.
-        ///
-        /// Stack: **=>**
-        LoopStart,
-
         /// Clean up environments when a loop continues.
         ///
         /// Operands:
@@ -1765,6 +1760,8 @@ generate_impl! {
         Reserved60 => Reserved,
         /// Reserved [`Opcode`].
         Reserved61 => Reserved,
+        /// Reserved [`Opcode`].
+        Reserved62 => Reserved,
     }
 }