Implement asynchronous evaluation of scripts (#3044)

* Implement asynchronous evaluation of scripts

* cargo fmt

* FIx fuzz build

* Reduce execution table size

---------

Co-authored-by: Haled Odat <8566042+HalidOdat@users.noreply.github.com>

boa_engine/src/script.rs

@@ -146,6 +146,52 @@ impl Script {
     pub fn evaluate(&self, context: &mut Context<'_>) -> JsResult<JsValue> {
         let _timer = Profiler::global().start_event("Execution", "Main");
 
+        self.prepare_run(context)?;
+        let record = context.run();
+
+        context.vm.pop_frame();
+        context.clear_kept_objects();
+
+        record.consume()
+    }
+
+    /// Evaluates this script and returns its result, periodically yielding to the executor
+    /// in order to avoid blocking the current thread.
+    ///
+    /// This uses an implementation defined amount of "clock cycles" that need to pass before
+    /// execution is suspended. See [`Script::evaluate_async_with_budget`] if you want to also
+    /// customize this parameter.
+    #[allow(clippy::future_not_send)]
+    pub async fn evaluate_async(&self, context: &mut Context<'_>) -> JsResult<JsValue> {
+        self.evaluate_async_with_budget(context, 256).await
+    }
+
+    /// Evaluates this script and returns its result, yielding to the executor each time `budget`
+    /// number of "clock cycles" pass.
+    ///
+    /// Note that "clock cycle" is in quotation marks because we can't determine exactly how many
+    /// CPU clock cycles a VM instruction will take, but all instructions have a "cost" associated
+    /// with them that depends on their individual complexity. We'd recommend benchmarking with
+    /// different budget sizes in order to find the ideal yielding time for your application.
+    #[allow(clippy::future_not_send)]
+    pub async fn evaluate_async_with_budget(
+        &self,
+        context: &mut Context<'_>,
+        budget: u32,
+    ) -> JsResult<JsValue> {
+        let _timer = Profiler::global().start_event("Async Execution", "Main");
+
+        self.prepare_run(context)?;
+
+        let record = context.run_async_with_budget(budget).await;
+
+        context.vm.pop_frame();
+        context.clear_kept_objects();
+
+        record.consume()
+    }
+
+    fn prepare_run(&self, context: &mut Context<'_>) -> JsResult<()> {
         let codeblock = self.codeblock(context)?;
 
         let env_fp = context.vm.environments.len() as u32;
@@ -165,11 +211,7 @@ impl Script {
         // TODO: Here should be https://tc39.es/ecma262/#sec-globaldeclarationinstantiation
 
         self.realm().resize_global_env();
-        let record = context.run();
-        context.vm.pop_frame();
 
-        context.clear_kept_objects();
+        Ok(())
-
-        record.consume()
     }
 }

boa_engine/src/vm/mod.rs

@@ -11,7 +11,7 @@ use crate::{
 
 use boa_gc::{custom_trace, Finalize, Trace};
 use boa_profiler::Profiler;
-use std::mem::size_of;
+use std::{future::Future, mem::size_of, ops::ControlFlow, pin::Pin, task};
 
 #[cfg(feature = "trace")]
 use boa_interner::ToInternedString;
@@ -292,7 +292,10 @@ impl Context<'_> {
         );
     }
 
-    fn trace_execute_instruction(&mut self) -> JsResult<CompletionType> {
+    fn trace_execute_instruction<F>(&mut self, f: F) -> JsResult<CompletionType>
+    where
+        F: FnOnce(Opcode, &mut Context<'_>) -> JsResult<CompletionType>,
+    {
         let bytecodes = &self.vm.frame().code_block.bytecode;
         let pc = self.vm.frame().pc as usize;
         let (_, varying_operand_kind, instruction) = InstructionIterator::with_pc(bytecodes, pc)
@@ -322,7 +325,7 @@ impl Context<'_> {
         }
 
         let instant = Instant::now();
-        let result = self.execute_instruction();
+        let result = self.execute_instruction(f);
         let duration = instant.elapsed();
 
         let fp = self.vm.frames.last().map(|frame| frame.fp as usize);
@@ -370,7 +373,10 @@ impl Context<'_> {
 }
 
 impl Context<'_> {
-    fn execute_instruction(&mut self) -> JsResult<CompletionType> {
+    fn execute_instruction<F>(&mut self, f: F) -> JsResult<CompletionType>
+    where
+        F: FnOnce(Opcode, &mut Context<'_>) -> JsResult<CompletionType>,
+    {
         let opcode: Opcode = {
             let _timer = Profiler::global().start_event("Opcode retrieval", "vm");
 
@@ -384,37 +390,32 @@ impl Context<'_> {
 
         let _timer = Profiler::global().start_event(opcode.as_instruction_str(), "vm");
 
-        opcode.execute(self)
+        f(opcode, self)
-    }
-
-    pub(crate) fn run(&mut self) -> CompletionRecord {
-        let _timer = Profiler::global().start_event("run", "vm");
-
-        #[cfg(feature = "trace")]
-        if self.vm.trace {
-            self.trace_call_frame();
     }
 
-        'instruction: loop {
+    fn execute_one<F>(&mut self, f: F) -> ControlFlow<CompletionRecord>
+    where
+        F: FnOnce(Opcode, &mut Context<'_>) -> JsResult<CompletionType>,
+    {
         #[cfg(feature = "fuzz")]
         {
             if self.instructions_remaining == 0 {
-                    return CompletionRecord::Throw(JsError::from_native(
+                return ControlFlow::Break(CompletionRecord::Throw(JsError::from_native(
                     JsNativeError::no_instructions_remain(),
-                    ));
+                )));
             }
             self.instructions_remaining -= 1;
         }
 
         #[cfg(feature = "trace")]
         let result = if self.vm.trace || self.vm.frame().code_block.traceable() {
-                self.trace_execute_instruction()
+            self.trace_execute_instruction(f)
         } else {
-                self.execute_instruction()
+            self.execute_instruction(f)
         };
 
         #[cfg(not(feature = "trace"))]
-            let result = self.execute_instruction();
+        let result = self.execute_instruction(f);
 
         let result = match result {
             Ok(result) => result,
@@ -435,14 +436,14 @@ impl Context<'_> {
                     }
                     self.vm.environments.truncate(env_fp);
                     self.vm.stack.truncate(fp);
-                        return CompletionRecord::Throw(err);
+                    return ControlFlow::Break(CompletionRecord::Throw(err));
                 }
 
                 // Note: -1 because we increment after fetching the opcode.
                 let pc = self.vm.frame().pc.saturating_sub(1);
                 if self.vm.handle_exception_at(pc) {
                     self.vm.pending_exception = Some(err);
-                        continue;
+                    return ControlFlow::Continue(());
                 }
 
                 // Inject realm before crossing the function boundry
@@ -460,7 +461,7 @@ impl Context<'_> {
 
                 let result = self.vm.take_return_value();
                 if self.vm.frame().exit_early() {
-                        return CompletionRecord::Normal(result);
+                    return ControlFlow::Break(CompletionRecord::Normal(result));
                 }
 
                 self.vm.push(result);
@@ -472,12 +473,12 @@ impl Context<'_> {
                 if self.vm.frame().exit_early() {
                     self.vm.environments.truncate(env_fp as usize);
                     self.vm.stack.truncate(fp as usize);
-                        return CompletionRecord::Throw(
+                    return ControlFlow::Break(CompletionRecord::Throw(
                         self.vm
                             .pending_exception
                             .take()
                             .expect("Err must exist for a CompletionType::Throw"),
-                        );
+                    ));
                 }
 
                 self.vm.pop_frame();
@@ -489,16 +490,16 @@ impl Context<'_> {
                     let exit_early = frame.exit_early();
 
                     if self.vm.handle_exception_at(pc) {
-                            continue 'instruction;
+                        return ControlFlow::Continue(());
                     }
 
                     if exit_early {
-                            return CompletionRecord::Throw(
+                        return ControlFlow::Break(CompletionRecord::Throw(
                             self.vm
                                 .pending_exception
                                 .take()
                                 .expect("Err must exist for a CompletionType::Throw"),
-                            );
+                        ));
                     }
 
                     self.vm.pop_frame();
@@ -510,13 +511,58 @@ impl Context<'_> {
             CompletionType::Yield => {
                 let result = self.vm.take_return_value();
                 if self.vm.frame().exit_early() {
-                        return CompletionRecord::Return(result);
+                    return ControlFlow::Break(CompletionRecord::Return(result));
                 }
 
                 self.vm.push(result);
                 self.vm.pop_frame();
             }
         }
+
+        ControlFlow::Continue(())
+    }
+
+    /// Runs the current frame to completion, yielding to the caller each time `budget`
+    /// "clock cycles" have passed.
+    #[allow(clippy::future_not_send)]
+    pub(crate) async fn run_async_with_budget(&mut self, budget: u32) -> CompletionRecord {
+        let _timer = Profiler::global().start_event("run_async_with_budget", "vm");
+
+        #[cfg(feature = "trace")]
+        if self.vm.trace {
+            self.trace_call_frame();
+        }
+
+        let mut runtime_budget: u32 = budget;
+
+        loop {
+            match self.execute_one(|opcode, context| {
+                opcode.spend_budget_and_execute(context, &mut runtime_budget)
+            }) {
+                ControlFlow::Continue(()) => {}
+                ControlFlow::Break(record) => return record,
+            }
+
+            if runtime_budget == 0 {
+                runtime_budget = budget;
+                yield_now().await;
+            }
+        }
+    }
+
+    pub(crate) fn run(&mut self) -> CompletionRecord {
+        let _timer = Profiler::global().start_event("run", "vm");
+
+        #[cfg(feature = "trace")]
+        if self.vm.trace {
+            self.trace_call_frame();
+        }
+
+        loop {
+            match self.execute_one(Opcode::execute) {
+                ControlFlow::Continue(()) => {}
+                ControlFlow::Break(value) => return value,
+            }
         }
     }
 
@@ -538,3 +584,24 @@ impl Context<'_> {
         Ok(())
     }
 }
+
+/// Yields once to the executor.
+fn yield_now() -> impl Future<Output = ()> {
+    struct YieldNow(bool);
+
+    impl Future for YieldNow {
+        type Output = ();
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> task::Poll<Self::Output> {
+            if self.0 {
+                task::Poll::Ready(())
+            } else {
+                self.0 = true;
+                cx.waker().wake_by_ref();
+                task::Poll::Pending
+            }
+        }
+    }
+
+    YieldNow(false)
+}

boa_engine/src/vm/opcode/await/mod.rs

@@ -18,6 +18,7 @@ pub(crate) struct Await;
 impl Operation for Await {
     const NAME: &'static str = "Await";
     const INSTRUCTION: &'static str = "INST - Await";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -150,6 +151,7 @@ pub(crate) struct CreatePromiseCapability;
 impl Operation for CreatePromiseCapability {
     const NAME: &'static str = "CreatePromiseCapability";
     const INSTRUCTION: &'static str = "INST - CreatePromiseCapability";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         if context.vm.frame().promise_capability.is_some() {
@@ -177,6 +179,7 @@ pub(crate) struct CompletePromiseCapability;
 impl Operation for CompletePromiseCapability {
     const NAME: &'static str = "CompletePromiseCapability";
     const INSTRUCTION: &'static str = "INST - CompletePromiseCapability";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // If the current executing function is an async function we have to resolve/reject it's promise at the end.

boa_engine/src/vm/opcode/binary_ops/logical.rs

@@ -13,6 +13,7 @@ pub(crate) struct LogicalAnd;
 impl Operation for LogicalAnd {
     const NAME: &'static str = "LogicalAnd";
     const INSTRUCTION: &'static str = "INST - LogicalAnd";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let exit = context.vm.read::<u32>();
@@ -35,6 +36,7 @@ pub(crate) struct LogicalOr;
 impl Operation for LogicalOr {
     const NAME: &'static str = "LogicalOr";
     const INSTRUCTION: &'static str = "INST - LogicalOr";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let exit = context.vm.read::<u32>();
@@ -57,6 +59,7 @@ pub(crate) struct Coalesce;
 impl Operation for Coalesce {
     const NAME: &'static str = "Coalesce";
     const INSTRUCTION: &'static str = "INST - Coalesce";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let exit = context.vm.read::<u32>();

boa_engine/src/vm/opcode/binary_ops/macro_defined.rs

@@ -15,6 +15,7 @@ macro_rules! implement_bin_ops {
         impl Operation for $name {
             const NAME: &'static str = stringify!($name);
             const INSTRUCTION: &'static str = stringify!("INST - " + $name);
+            const COST: u8 = 2;
 
             fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
                 let rhs = context.vm.pop();

boa_engine/src/vm/opcode/binary_ops/mod.rs

@@ -20,6 +20,7 @@ pub(crate) struct NotEq;
 impl Operation for NotEq {
     const NAME: &'static str = "NotEq";
     const INSTRUCTION: &'static str = "INST - NotEq";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let rhs = context.vm.pop();
@@ -40,6 +41,7 @@ pub(crate) struct StrictEq;
 impl Operation for StrictEq {
     const NAME: &'static str = "StrictEq";
     const INSTRUCTION: &'static str = "INST - StrictEq";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let rhs = context.vm.pop();
@@ -59,6 +61,7 @@ pub(crate) struct StrictNotEq;
 impl Operation for StrictNotEq {
     const NAME: &'static str = "StrictNotEq";
     const INSTRUCTION: &'static str = "INST - StrictNotEq";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let rhs = context.vm.pop();
@@ -78,6 +81,7 @@ pub(crate) struct In;
 impl Operation for In {
     const NAME: &'static str = "In";
     const INSTRUCTION: &'static str = "INST - In";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let rhs = context.vm.pop();
@@ -137,6 +141,7 @@ impl InPrivate {
 impl Operation for InPrivate {
     const NAME: &'static str = "InPrivate";
     const INSTRUCTION: &'static str = "INST - InPrivate";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -164,6 +169,7 @@ pub(crate) struct InstanceOf;
 impl Operation for InstanceOf {
     const NAME: &'static str = "InstanceOf";
     const INSTRUCTION: &'static str = "INST - InstanceOf";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let target = context.vm.pop();

boa_engine/src/vm/opcode/call/mod.rs

@@ -63,6 +63,9 @@ impl CallEval {
 impl Operation for CallEval {
     const NAME: &'static str = "CallEval";
     const INSTRUCTION: &'static str = "INST - CallEval";
+    // TODO: Calls will require a big refactor in order to track
+    // the cost of the call.
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let argument_count = context.vm.read::<u8>();
@@ -90,6 +93,9 @@ pub(crate) struct CallEvalSpread;
 impl Operation for CallEvalSpread {
     const NAME: &'static str = "CallEvalSpread";
     const INSTRUCTION: &'static str = "INST - CallEvalSpread";
+    // TODO: Calls will require a big refactor in order to track
+    // the cost of the call.
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Get the arguments that are stored as an array object on the stack.
@@ -176,6 +182,7 @@ impl Call {
 impl Operation for Call {
     const NAME: &'static str = "Call";
     const INSTRUCTION: &'static str = "INST - Call";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let argument_count = context.vm.read::<u8>();
@@ -199,6 +206,7 @@ pub(crate) struct CallSpread;
 impl Operation for CallSpread {
     const NAME: &'static str = "CallSpread";
     const INSTRUCTION: &'static str = "INST - CallSpread";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Get the arguments that are stored as an array object on the stack.
@@ -240,6 +248,7 @@ pub(crate) struct ImportCall;
 impl Operation for ImportCall {
     const NAME: &'static str = "ImportCall";
     const INSTRUCTION: &'static str = "INST - ImportCall";
+    const COST: u8 = 15;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Import Calls

boa_engine/src/vm/opcode/concat/mod.rs

@@ -31,6 +31,7 @@ impl ConcatToString {
 impl Operation for ConcatToString {
     const NAME: &'static str = "ConcatToString";
     const INSTRUCTION: &'static str = "INST - ConcatToString";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value_count = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/control_flow/jump.rs

@@ -13,6 +13,7 @@ pub(crate) struct Jump;
 impl Operation for Jump {
     const NAME: &'static str = "Jump";
     const INSTRUCTION: &'static str = "INST - Jump";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let address = context.vm.read::<u32>();
@@ -31,6 +32,7 @@ pub(crate) struct JumpIfTrue;
 impl Operation for JumpIfTrue {
     const NAME: &'static str = "JumpIfTrue";
     const INSTRUCTION: &'static str = "INST - JumpIfTrue";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let address = context.vm.read::<u32>();
@@ -51,6 +53,7 @@ pub(crate) struct JumpIfFalse;
 impl Operation for JumpIfFalse {
     const NAME: &'static str = "JumpIfFalse";
     const INSTRUCTION: &'static str = "INST - JumpIfFalse";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let address = context.vm.read::<u32>();
@@ -71,6 +74,7 @@ pub(crate) struct JumpIfNotUndefined;
 impl Operation for JumpIfNotUndefined {
     const NAME: &'static str = "JumpIfNotUndefined";
     const INSTRUCTION: &'static str = "INST - JumpIfNotUndefined";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let address = context.vm.read::<u32>();
@@ -93,6 +97,7 @@ pub(crate) struct JumpIfNullOrUndefined;
 impl Operation for JumpIfNullOrUndefined {
     const NAME: &'static str = "JumpIfNullOrUndefined";
     const INSTRUCTION: &'static str = "INST - JumpIfNullOrUndefined";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let address = context.vm.read::<u32>();
@@ -116,6 +121,7 @@ pub(crate) struct JumpTable;
 impl Operation for JumpTable {
     const NAME: &'static str = "JumpTable";
     const INSTRUCTION: &'static str = "INST - JumpTable";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let default = context.vm.read::<u32>();

boa_engine/src/vm/opcode/control_flow/return.rs

@@ -13,6 +13,7 @@ pub(crate) struct Return;
 impl Operation for Return {
     const NAME: &'static str = "Return";
     const INSTRUCTION: &'static str = "INST - Return";
+    const COST: u8 = 4;
 
     fn execute(_context: &mut Context<'_>) -> JsResult<CompletionType> {
         Ok(CompletionType::Return)
@@ -29,6 +30,7 @@ pub(crate) struct CheckReturn;
 impl Operation for CheckReturn {
     const NAME: &'static str = "CheckReturn";
     const INSTRUCTION: &'static str = "INST - CheckReturn";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         if !context.vm.frame().construct() {
@@ -80,6 +82,7 @@ pub(crate) struct GetReturnValue;
 impl Operation for GetReturnValue {
     const NAME: &'static str = "GetReturnValue";
     const INSTRUCTION: &'static str = "INST - GetReturnValue";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.get_return_value();
@@ -98,6 +101,7 @@ pub(crate) struct SetReturnValue;
 impl Operation for SetReturnValue {
     const NAME: &'static str = "SetReturnValue";
     const INSTRUCTION: &'static str = "INST - SetReturnValue";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/control_flow/throw.rs

@@ -13,6 +13,7 @@ pub(crate) struct Throw;
 impl Operation for Throw {
     const NAME: &'static str = "Throw";
     const INSTRUCTION: &'static str = "INST - Throw";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let error = JsError::from_opaque(context.vm.pop());
@@ -38,6 +39,7 @@ pub(crate) struct ReThrow;
 impl Operation for ReThrow {
     const NAME: &'static str = "ReThrow";
     const INSTRUCTION: &'static str = "INST - ReThrow";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Note: -1 because we increment after fetching the opcode.
@@ -69,6 +71,7 @@ pub(crate) struct Exception;
 impl Operation for Exception {
     const NAME: &'static str = "Exception";
     const INSTRUCTION: &'static str = "INST - Exception";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         if let Some(error) = context.vm.pending_exception.take() {
@@ -96,6 +99,7 @@ pub(crate) struct MaybeException;
 impl Operation for MaybeException {
     const NAME: &'static str = "MaybeException";
     const INSTRUCTION: &'static str = "INST - MaybeException";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         if let Some(error) = context.vm.pending_exception.take() {
@@ -133,6 +137,7 @@ impl ThrowNewTypeError {
 impl Operation for ThrowNewTypeError {
     const NAME: &'static str = "ThrowNewTypeError";
     const INSTRUCTION: &'static str = "INST - ThrowNewTypeError";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/copy/mod.rs

@@ -43,6 +43,7 @@ impl CopyDataProperties {
 impl Operation for CopyDataProperties {
     const NAME: &'static str = "CopyDataProperties";
     const INSTRUCTION: &'static str = "INST - CopyDataProperties";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let excluded_key_count = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/define/class/getter.rs

@@ -51,6 +51,7 @@ impl DefineClassStaticGetterByName {
 impl Operation for DefineClassStaticGetterByName {
     const NAME: &'static str = "DefineClassStaticGetterByName";
     const INSTRUCTION: &'static str = "INST - DefineClassStaticGetterByName";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -114,6 +115,7 @@ impl DefineClassGetterByName {
 impl Operation for DefineClassGetterByName {
     const NAME: &'static str = "DefineClassGetterByName";
     const INSTRUCTION: &'static str = "INST - DefineClassGetterByName";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -141,6 +143,7 @@ pub(crate) struct DefineClassStaticGetterByValue;
 impl Operation for DefineClassStaticGetterByValue {
     const NAME: &'static str = "DefineClassStaticGetterByValue";
     const INSTRUCTION: &'static str = "INST - DefineClassStaticGetterByValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();
@@ -190,6 +193,7 @@ pub(crate) struct DefineClassGetterByValue;
 impl Operation for DefineClassGetterByValue {
     const NAME: &'static str = "DefineClassGetterByValue";
     const INSTRUCTION: &'static str = "INST - DefineClassGetterByValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();

boa_engine/src/vm/opcode/define/class/method.rs

@@ -47,6 +47,7 @@ impl DefineClassStaticMethodByName {
 impl Operation for DefineClassStaticMethodByName {
     const NAME: &'static str = "DefineClassStaticMethodByName";
     const INSTRUCTION: &'static str = "INST - DefineClassStaticMethodByName";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -106,6 +107,7 @@ impl DefineClassMethodByName {
 impl Operation for DefineClassMethodByName {
     const NAME: &'static str = "DefineClassMethodByName";
     const INSTRUCTION: &'static str = "INST - DefineClassMethodByName";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -133,6 +135,7 @@ pub(crate) struct DefineClassStaticMethodByValue;
 impl Operation for DefineClassStaticMethodByValue {
     const NAME: &'static str = "DefineClassStaticMethodByValue";
     const INSTRUCTION: &'static str = "INST - DefineClassStaticMethodByValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();
@@ -178,6 +181,7 @@ pub(crate) struct DefineClassMethodByValue;
 impl Operation for DefineClassMethodByValue {
     const NAME: &'static str = "DefineClassMethodByValue";
     const INSTRUCTION: &'static str = "INST - DefineClassMethodByValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();

boa_engine/src/vm/opcode/define/class/setter.rs

@@ -52,6 +52,7 @@ impl DefineClassStaticSetterByName {
 impl Operation for DefineClassStaticSetterByName {
     const NAME: &'static str = "DefineClassStaticSetterByName";
     const INSTRUCTION: &'static str = "INST - DefineClassStaticSetterByName";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -117,6 +118,7 @@ impl DefineClassSetterByName {
 impl Operation for DefineClassSetterByName {
     const NAME: &'static str = "DefineClassSetterByName";
     const INSTRUCTION: &'static str = "INST - DefineClassSetterByName";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -144,6 +146,7 @@ pub(crate) struct DefineClassStaticSetterByValue;
 impl Operation for DefineClassStaticSetterByValue {
     const NAME: &'static str = "DefineClassStaticSetterByValue";
     const INSTRUCTION: &'static str = "INST - DefineClassStaticSetterByValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();
@@ -195,6 +198,7 @@ pub(crate) struct DefineClassSetterByValue;
 impl Operation for DefineClassSetterByValue {
     const NAME: &'static str = "DefineClassSetterByValue";
     const INSTRUCTION: &'static str = "INST - DefineClassSetterByValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();

boa_engine/src/vm/opcode/define/mod.rs

@@ -38,6 +38,7 @@ impl DefVar {
 impl Operation for DefVar {
     const NAME: &'static str = "DefVar";
     const INSTRUCTION: &'static str = "INST - DefVar";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -80,6 +81,7 @@ impl DefInitVar {
 impl Operation for DefInitVar {
     const NAME: &'static str = "DefInitVar";
     const INSTRUCTION: &'static str = "INST - DefInitVar";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -122,6 +124,7 @@ impl PutLexicalValue {
 impl Operation for PutLexicalValue {
     const NAME: &'static str = "PutLexicalValue";
     const INSTRUCTION: &'static str = "INST - PutLexicalValue";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();

boa_engine/src/vm/opcode/define/own_property.rs

@@ -38,6 +38,7 @@ impl DefineOwnPropertyByName {
 impl Operation for DefineOwnPropertyByName {
     const NAME: &'static str = "DefineOwnPropertyByName";
     const INSTRUCTION: &'static str = "INST - DefineOwnPropertyByName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -65,6 +66,7 @@ pub(crate) struct DefineOwnPropertyByValue;
 impl Operation for DefineOwnPropertyByValue {
     const NAME: &'static str = "DefineOwnPropertyByValue";
     const INSTRUCTION: &'static str = "INST - DefineOwnPropertyByValue";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/delete/mod.rs

@@ -30,6 +30,7 @@ impl DeletePropertyByName {
 impl Operation for DeletePropertyByName {
     const NAME: &'static str = "DeletePropertyByName";
     const INSTRUCTION: &'static str = "INST - DeletePropertyByName";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -57,6 +58,7 @@ pub(crate) struct DeletePropertyByValue;
 impl Operation for DeletePropertyByValue {
     const NAME: &'static str = "DeletePropertyByValue";
     const INSTRUCTION: &'static str = "INST - DeletePropertyByValue";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let key_value = context.vm.pop();
@@ -97,6 +99,7 @@ impl DeleteName {
 impl Operation for DeleteName {
     const NAME: &'static str = "DeleteName";
     const INSTRUCTION: &'static str = "INST - DeleteName";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -124,6 +127,7 @@ pub(crate) struct DeleteSuperThrow;
 impl Operation for DeleteSuperThrow {
     const NAME: &'static str = "DeleteSuperThrow";
     const INSTRUCTION: &'static str = "INST - DeleteSuperThrow";
+    const COST: u8 = 2;
 
     fn execute(_: &mut Context<'_>) -> JsResult<CompletionType> {
         Err(JsNativeError::reference()

boa_engine/src/vm/opcode/dup/mod.rs

@@ -13,6 +13,7 @@ pub(crate) struct Dup;
 impl Operation for Dup {
     const NAME: &'static str = "Dup";
     const INSTRUCTION: &'static str = "INST - Dup";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/environment/mod.rs

@@ -14,6 +14,7 @@ pub(crate) struct This;
 impl Operation for This {
     const NAME: &'static str = "This";
     const INSTRUCTION: &'static str = "INST - This";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let this = context.vm.environments.get_this_binding()?;
@@ -32,6 +33,7 @@ pub(crate) struct Super;
 impl Operation for Super {
     const NAME: &'static str = "Super";
     const INSTRUCTION: &'static str = "INST - Super";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let home_object = {
@@ -72,6 +74,7 @@ pub(crate) struct SuperCallPrepare;
 impl Operation for SuperCallPrepare {
     const NAME: &'static str = "SuperCallPrepare";
     const INSTRUCTION: &'static str = "INST - SuperCallPrepare";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let this_env = context
@@ -134,6 +137,7 @@ impl SuperCall {
 impl Operation for SuperCall {
     const NAME: &'static str = "SuperCall";
     const INSTRUCTION: &'static str = "INST - SuperCall";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value_count = context.vm.read::<u8>() as usize;
@@ -161,6 +165,7 @@ pub(crate) struct SuperCallSpread;
 impl Operation for SuperCallSpread {
     const NAME: &'static str = "SuperCallSpread";
     const INSTRUCTION: &'static str = "INST - SuperCallSpread";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Get the arguments that are stored as an array object on the stack.
@@ -219,6 +224,7 @@ pub(crate) struct SuperCallDerived;
 impl Operation for SuperCallDerived {
     const NAME: &'static str = "SuperCallDerived";
     const INSTRUCTION: &'static str = "INST - SuperCallDerived";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let argument_count = context.vm.frame().argument_count as usize;
@@ -271,6 +277,7 @@ pub(crate) struct BindThisValue;
 impl Operation for BindThisValue {
     const NAME: &'static str = "BindThisValue";
     const INSTRUCTION: &'static str = "INST - BindThisValue";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Taken from `SuperCall : super Arguments` steps 7-12.

boa_engine/src/vm/opcode/generator/mod.rs

@@ -32,6 +32,7 @@ pub(crate) struct Generator;
 impl Operation for Generator {
     const NAME: &'static str = "Generator";
     const INSTRUCTION: &'static str = "INST - Generator";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let r#async = context.vm.read::<u8>() != 0;
@@ -128,6 +129,7 @@ pub(crate) struct AsyncGeneratorClose;
 impl Operation for AsyncGeneratorClose {
     const NAME: &'static str = "AsyncGeneratorClose";
     const INSTRUCTION: &'static str = "INST - AsyncGeneratorClose";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Step 3.e-g in [AsyncGeneratorStart](https://tc39.es/ecma262/#sec-asyncgeneratorstart)
@@ -176,6 +178,7 @@ pub(crate) struct GeneratorNext;
 impl Operation for GeneratorNext {
     const NAME: &'static str = "GeneratorNext";
     const INSTRUCTION: &'static str = "INST - GeneratorNext";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let generator_resume_kind = context.vm.pop().to_generator_resume_kind();
@@ -202,6 +205,7 @@ pub(crate) struct JumpIfNotResumeKind;
 impl Operation for JumpIfNotResumeKind {
     const NAME: &'static str = "JumpIfNotResumeKind";
     const INSTRUCTION: &'static str = "INST - JumpIfNotResumeKind";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let exit = context.vm.read::<u32>();
@@ -228,6 +232,7 @@ pub(crate) struct GeneratorDelegateNext;
 impl Operation for GeneratorDelegateNext {
     const NAME: &'static str = "GeneratorDelegateNext";
     const INSTRUCTION: &'static str = "INST - GeneratorDelegateNext";
+    const COST: u8 = 18;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let throw_method_undefined = context.vm.read::<u32>();
@@ -317,6 +322,7 @@ pub(crate) struct GeneratorDelegateResume;
 impl Operation for GeneratorDelegateResume {
     const NAME: &'static str = "GeneratorDelegateResume";
     const INSTRUCTION: &'static str = "INST - GeneratorDelegateResume";
+    const COST: u8 = 7;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let return_gen = context.vm.read::<u32>();

boa_engine/src/vm/opcode/generator/yield_stm.rs

@@ -14,6 +14,7 @@ pub(crate) struct GeneratorYield;
 impl Operation for GeneratorYield {
     const NAME: &'static str = "GeneratorYield";
     const INSTRUCTION: &'static str = "INST - GeneratorYield";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -32,6 +33,7 @@ pub(crate) struct AsyncGeneratorYield;
 impl Operation for AsyncGeneratorYield {
     const NAME: &'static str = "AsyncGeneratorYield";
     const INSTRUCTION: &'static str = "INST - AsyncGeneratorYield";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/get/argument.rs

@@ -29,6 +29,7 @@ impl GetArgument {
 impl Operation for GetArgument {
     const NAME: &'static str = "GetArgument";
     const INSTRUCTION: &'static str = "INST - GetArgument";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/get/function.rs

@@ -23,6 +23,7 @@ impl GetArrowFunction {
 impl Operation for GetArrowFunction {
     const NAME: &'static str = "GetArrowFunction";
     const INSTRUCTION: &'static str = "INST - GetArrowFunction";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -60,6 +61,7 @@ impl GetAsyncArrowFunction {
 impl Operation for GetAsyncArrowFunction {
     const NAME: &'static str = "GetAsyncArrowFunction";
     const INSTRUCTION: &'static str = "INST - GetAsyncArrowFunction";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -101,6 +103,7 @@ impl GetFunction {
 impl Operation for GetFunction {
     const NAME: &'static str = "GetFunction";
     const INSTRUCTION: &'static str = "INST - GetFunction";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -145,6 +148,7 @@ impl GetFunctionAsync {
 impl Operation for GetFunctionAsync {
     const NAME: &'static str = "GetFunctionAsync";
     const INSTRUCTION: &'static str = "INST - GetFunctionAsync";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/get/generator.rs

@@ -23,6 +23,7 @@ impl GetGenerator {
 impl Operation for GetGenerator {
     const NAME: &'static str = "GetGenerator";
     const INSTRUCTION: &'static str = "INST - GetGenerator";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -60,6 +61,7 @@ impl GetGeneratorAsync {
 impl Operation for GetGeneratorAsync {
     const NAME: &'static str = "GetGeneratorAsync";
     const INSTRUCTION: &'static str = "INST - GetGeneratorAsync";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/get/name.rs

@@ -31,6 +31,7 @@ impl GetName {
 impl Operation for GetName {
     const NAME: &'static str = "GetName";
     const INSTRUCTION: &'static str = "INST - GetName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -69,6 +70,7 @@ impl GetLocator {
 impl Operation for GetLocator {
     const NAME: &'static str = "GetLocator";
     const INSTRUCTION: &'static str = "INST - GetLocator";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -115,6 +117,7 @@ impl GetNameAndLocator {
 impl Operation for GetNameAndLocator {
     const NAME: &'static str = "GetNameAndLocator";
     const INSTRUCTION: &'static str = "INST - GetNameAndLocator";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -169,6 +172,7 @@ impl GetNameOrUndefined {
 impl Operation for GetNameOrUndefined {
     const NAME: &'static str = "GetNameOrUndefined";
     const INSTRUCTION: &'static str = "INST - GetNameOrUndefined";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();

boa_engine/src/vm/opcode/get/private.rs

@@ -31,6 +31,7 @@ impl GetPrivateField {
 impl Operation for GetPrivateField {
     const NAME: &'static str = "GetPrivateField";
     const INSTRUCTION: &'static str = "INST - GetPrivateField";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/get/property.rs

@@ -32,6 +32,7 @@ impl GetPropertyByName {
 impl Operation for GetPropertyByName {
     const NAME: &'static str = "GetPropertyByName";
     const INSTRUCTION: &'static str = "INST - GetPropertyByName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -59,6 +60,7 @@ pub(crate) struct GetPropertyByValue;
 impl Operation for GetPropertyByValue {
     const NAME: &'static str = "GetPropertyByValue";
     const INSTRUCTION: &'static str = "INST - GetPropertyByValue";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let key = context.vm.pop();
@@ -105,6 +107,7 @@ pub(crate) struct GetPropertyByValuePush;
 impl Operation for GetPropertyByValuePush {
     const NAME: &'static str = "GetPropertyByValuePush";
     const INSTRUCTION: &'static str = "INST - GetPropertyByValuePush";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let key = context.vm.pop();

boa_engine/src/vm/opcode/iteration/for_in.rs

@@ -15,6 +15,7 @@ pub(crate) struct CreateForInIterator;
 impl Operation for CreateForInIterator {
     const NAME: &'static str = "CreateForInIterator";
     const INSTRUCTION: &'static str = "INST - CreateForInIterator";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let object = context.vm.pop();

boa_engine/src/vm/opcode/iteration/get.rs

@@ -14,6 +14,7 @@ pub(crate) struct GetIterator;
 impl Operation for GetIterator {
     const NAME: &'static str = "GetIterator";
     const INSTRUCTION: &'static str = "INST - GetIterator";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let object = context.vm.pop();
@@ -33,6 +34,7 @@ pub(crate) struct GetAsyncIterator;
 impl Operation for GetAsyncIterator {
     const NAME: &'static str = "GetAsyncIterator";
     const INSTRUCTION: &'static str = "INST - GetAsyncIterator";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let object = context.vm.pop();

boa_engine/src/vm/opcode/iteration/iterator.rs

@@ -17,6 +17,7 @@ pub(crate) struct IteratorNext;
 impl Operation for IteratorNext {
     const NAME: &'static str = "IteratorNext";
     const INSTRUCTION: &'static str = "INST - IteratorNext";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context
@@ -44,6 +45,7 @@ pub(crate) struct IteratorNextWithoutPop;
 impl Operation for IteratorNextWithoutPop {
     const NAME: &'static str = "IteratorNextWithoutPop";
     const INSTRUCTION: &'static str = "INST - IteratorNextWithoutPop";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context
@@ -74,6 +76,7 @@ pub(crate) struct IteratorFinishAsyncNext;
 impl Operation for IteratorFinishAsyncNext {
     const NAME: &'static str = "IteratorFinishAsyncNext";
     const INSTRUCTION: &'static str = "INST - IteratorFinishAsyncNext";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context
@@ -115,6 +118,7 @@ pub(crate) struct IteratorResult;
 impl Operation for IteratorResult {
     const NAME: &'static str = "IteratorResult";
     const INSTRUCTION: &'static str = "INST - IteratorResult";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let last_result = context
@@ -143,6 +147,7 @@ pub(crate) struct IteratorValue;
 impl Operation for IteratorValue {
     const NAME: &'static str = "IteratorValue";
     const INSTRUCTION: &'static str = "INST - IteratorValue";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context
@@ -171,6 +176,7 @@ pub(crate) struct IteratorValueWithoutPop;
 impl Operation for IteratorValueWithoutPop {
     const NAME: &'static str = "IteratorValueWithoutPop";
     const INSTRUCTION: &'static str = "INST - IteratorValueWithoutPop";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context
@@ -199,6 +205,7 @@ pub(crate) struct IteratorDone;
 impl Operation for IteratorDone {
     const NAME: &'static str = "IteratorDone";
     const INSTRUCTION: &'static str = "INST - IteratorDone";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let done = context
@@ -225,6 +232,7 @@ pub(crate) struct IteratorReturn;
 impl Operation for IteratorReturn {
     const NAME: &'static str = "IteratorReturn";
     const INSTRUCTION: &'static str = "INST - IteratorReturn";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let record = context
@@ -261,6 +269,7 @@ pub(crate) struct IteratorToArray;
 impl Operation for IteratorToArray {
     const NAME: &'static str = "IteratorToArray";
     const INSTRUCTION: &'static str = "INST - IteratorToArray";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context
@@ -314,6 +323,7 @@ pub(crate) struct IteratorPop;
 impl Operation for IteratorPop {
     const NAME: &'static str = "IteratorPop";
     const INSTRUCTION: &'static str = "INST - IteratorPop";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         context.vm.frame_mut().iterators.pop();
@@ -331,6 +341,7 @@ pub(crate) struct IteratorStackEmpty;
 impl Operation for IteratorStackEmpty {
     const NAME: &'static str = "IteratorStackEmpty";
     const INSTRUCTION: &'static str = "INST - IteratorStackEmpty";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let is_empty = context.vm.frame().iterators.is_empty();
@@ -349,6 +360,7 @@ pub(crate) struct CreateIteratorResult;
 impl Operation for CreateIteratorResult {
     const NAME: &'static str = "CreateIteratorResult";
     const INSTRUCTION: &'static str = "INST - CreateIteratorResult";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/iteration/loop_ops.rs

@@ -14,6 +14,7 @@ pub(crate) struct IncrementLoopIteration;
 impl Operation for IncrementLoopIteration {
     const NAME: &'static str = "IncrementLoopIteration";
     const INSTRUCTION: &'static str = "INST - IncrementLoopIteration";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let previous_iteration_count = context.vm.frame_mut().loop_iteration_count;

boa_engine/src/vm/opcode/meta/mod.rs

@@ -16,6 +16,7 @@ pub(crate) struct NewTarget;
 impl Operation for NewTarget {
     const NAME: &'static str = "NewTarget";
     const INSTRUCTION: &'static str = "INST - NewTarget";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let new_target = if let Some(new_target) = context
@@ -44,6 +45,7 @@ pub(crate) struct ImportMeta;
 impl Operation for ImportMeta {
     const NAME: &'static str = "ImportMeta";
     const INSTRUCTION: &'static str = "INST - ImportMeta";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Meta Properties

boa_engine/src/vm/opcode/mod.rs

@@ -396,11 +396,11 @@ macro_rules! generate_opcodes {
         }
 
         impl Opcode {
-            const MAX: usize = 2usize.pow(8) * 3;
+            const MAX: usize = 2usize.pow(8);
 
             // TODO: see if this can be exposed on all features.
             #[allow(unused)]
-            const NAMES: [&'static str; Self::MAX] = [
+            const NAMES: [&'static str; Self::MAX * 3] = [
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::NAME),*,
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::NAME),*,
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::NAME),*
@@ -414,7 +414,7 @@ macro_rules! generate_opcodes {
                 Self::NAMES[self as usize]
             }
 
-            const INSTRUCTIONS: [&'static str; Self::MAX] = [
+            const INSTRUCTIONS: [&'static str; Self::MAX * 3] = [
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::INSTRUCTION),*,
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::INSTRUCTION),*,
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::INSTRUCTION),*
@@ -426,7 +426,29 @@ macro_rules! generate_opcodes {
                 Self::INSTRUCTIONS[self as usize]
             }
 
-            const EXECUTE_FNS: [fn(&mut Context<'_>) -> JsResult<CompletionType>; Self::MAX] = [
+            const SPEND_FNS: [fn(&mut Context<'_>, &mut u32) -> JsResult<CompletionType>; Self::MAX] = [
+                $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::spend_budget_and_execute),*,
+            ];
+
+            /// Spends the cost of this opcode into the provided budget and executes it.
+            pub(super) fn spend_budget_and_execute(
+                self,
+                context: &mut Context<'_>,
+                budget: &mut u32
+            ) -> JsResult<CompletionType> {
+                Self::SPEND_FNS[self as usize](context, budget)
+            }
+
+            const COSTS: [u8; Self::MAX] = [
+                $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::COST),*,
+            ];
+
+            /// Return the cost of this opcode.
+            pub(super) const fn cost(self) -> u8 {
+                Self::COSTS[self as usize]
+            }
+
+            const EXECUTE_FNS: [fn(&mut Context<'_>) -> JsResult<CompletionType>; Self::MAX * 3] = [
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::execute),*,
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::execute_with_u16_operands),*,
                 $(<generate_opcodes!(name $Variant $(=> $mapping)?)>::execute_with_u32_operands),*
@@ -440,7 +462,7 @@ macro_rules! generate_opcodes {
         /// This represents a VM instruction, it contains both opcode and operands.
         ///
         // TODO: An instruction should be a representation of a valid executable instruction (opcode + operands),
-        //       so variants like `ResevedN`, or operand width prefix modifiers, idealy shouldn't
+        //       so variants like `ReservedN`, or operand width prefix modifiers, idealy shouldn't
         //       be a part of `Instruction`.
         #[derive(Debug, Clone, PartialEq)]
         #[repr(u8)]
@@ -530,6 +552,7 @@ macro_rules! generate_opcodes {
 pub(crate) trait Operation {
     const NAME: &'static str;
     const INSTRUCTION: &'static str;
+    const COST: u8;
 
     /// Execute opcode with [`VaryingOperandKind::U8`] sized [`VaryingOperand`]s.
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType>;
@@ -547,6 +570,15 @@ pub(crate) trait Operation {
     fn execute_with_u32_operands(context: &mut Context<'_>) -> JsResult<CompletionType> {
         Reserved::execute_with_u32_operands(context)
     }
+
+    /// Spends the cost of this operation into `budget` and runs `execute`.
+    fn spend_budget_and_execute(
+        context: &mut Context<'_>,
+        budget: &mut u32,
+    ) -> JsResult<CompletionType> {
+        *budget = budget.saturating_sub(u32::from(Self::COST));
+        Self::execute(context)
+    }
 }
 
 generate_opcodes! {

boa_engine/src/vm/opcode/modifier.rs

@@ -12,11 +12,22 @@ pub(crate) struct U16Operands;
 impl Operation for U16Operands {
     const NAME: &'static str = "U16Operands";
     const INSTRUCTION: &'static str = "INST - U16Operands";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let opcode = context.vm.read::<u8>() as usize;
 
-        Opcode::EXECUTE_FNS[256 + opcode](context)
+        Opcode::EXECUTE_FNS[Opcode::MAX + opcode](context)
+    }
+
+    fn spend_budget_and_execute(
+        context: &mut Context<'_>,
+        budget: &mut u32,
+    ) -> JsResult<CompletionType> {
+        let opcode: Opcode = context.vm.read::<u8>().into();
+
+        *budget = budget.saturating_sub(u32::from(opcode.cost()) + u32::from(Self::COST));
+        Opcode::EXECUTE_FNS[Opcode::MAX + opcode as usize](context)
     }
 }
 
@@ -30,10 +41,21 @@ pub(crate) struct U32Operands;
 impl Operation for U32Operands {
     const NAME: &'static str = "U32Operands";
     const INSTRUCTION: &'static str = "INST - U32Operands";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let opcode = context.vm.read::<u8>() as usize;
 
-        Opcode::EXECUTE_FNS[256 * 2 + opcode](context)
+        Opcode::EXECUTE_FNS[Opcode::MAX * 2 + opcode](context)
+    }
+
+    fn spend_budget_and_execute(
+        context: &mut Context<'_>,
+        budget: &mut u32,
+    ) -> JsResult<CompletionType> {
+        let opcode: Opcode = context.vm.read::<u8>().into();
+
+        *budget = budget.saturating_sub(u32::from(opcode.cost()) + u32::from(Self::COST));
+        Opcode::EXECUTE_FNS[Opcode::MAX * 2 + opcode as usize](context)
     }
 }

boa_engine/src/vm/opcode/new/mod.rs

@@ -31,6 +31,7 @@ impl New {
 impl Operation for New {
     const NAME: &'static str = "New";
     const INSTRUCTION: &'static str = "INST - New";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let argument_count = context.vm.read::<u8>() as usize;
@@ -58,6 +59,7 @@ pub(crate) struct NewSpread;
 impl Operation for NewSpread {
     const NAME: &'static str = "NewSpread";
     const INSTRUCTION: &'static str = "INST - NewSpread";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         // Get the arguments that are stored as an array object on the stack.

boa_engine/src/vm/opcode/nop/mod.rs

@@ -13,6 +13,7 @@ pub(crate) struct Nop;
 impl Operation for Nop {
     const NAME: &'static str = "Nop";
     const INSTRUCTION: &'static str = "INST - Nop";
+    const COST: u8 = 1;
 
     fn execute(_: &mut Context<'_>) -> JsResult<CompletionType> {
         Ok(CompletionType::Normal)
@@ -29,6 +30,7 @@ pub(crate) struct Reserved;
 impl Operation for Reserved {
     const NAME: &'static str = "Reserved";
     const INSTRUCTION: &'static str = "INST - Reserved";
+    const COST: u8 = 0;
 
     fn execute(_: &mut Context<'_>) -> JsResult<CompletionType> {
         unreachable!("Reserved opcodes are unreachable!")

boa_engine/src/vm/opcode/pop/mod.rs

@@ -13,6 +13,7 @@ pub(crate) struct Pop;
 impl Operation for Pop {
     const NAME: &'static str = "Pop";
     const INSTRUCTION: &'static str = "INST - Pop";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let _val = context.vm.pop();
@@ -30,6 +31,7 @@ pub(crate) struct PopEnvironment;
 impl Operation for PopEnvironment {
     const NAME: &'static str = "PopEnvironment";
     const INSTRUCTION: &'static str = "INST - PopEnvironment";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         context.vm.environments.pop();

boa_engine/src/vm/opcode/push/array.rs

@@ -16,6 +16,7 @@ pub(crate) struct PushNewArray;
 impl Operation for PushNewArray {
     const NAME: &'static str = "PushNewArray";
     const INSTRUCTION: &'static str = "INST - PushNewArray";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let array = context
@@ -38,6 +39,7 @@ pub(crate) struct PushValueToArray;
 impl Operation for PushValueToArray {
     const NAME: &'static str = "PushValueToArray";
     const INSTRUCTION: &'static str = "INST - PushValueToArray";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -63,6 +65,7 @@ pub(crate) struct PushElisionToArray;
 impl Operation for PushElisionToArray {
     const NAME: &'static str = "PushElisionToArray";
     const INSTRUCTION: &'static str = "INST - PushElisionToArray";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let array = context.vm.pop();
@@ -88,6 +91,7 @@ pub(crate) struct PushIteratorToArray;
 impl Operation for PushIteratorToArray {
     const NAME: &'static str = "PushIteratorToArray";
     const INSTRUCTION: &'static str = "INST - PushIteratorToArray";
+    const COST: u8 = 8;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let mut iterator = context

boa_engine/src/vm/opcode/push/class/field.rs

@@ -14,6 +14,7 @@ pub(crate) struct PushClassField;
 impl Operation for PushClassField {
     const NAME: &'static str = "PushClassField";
     const INSTRUCTION: &'static str = "INST - PushClassField";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let field_function_value = context.vm.pop();
@@ -85,6 +86,7 @@ impl PushClassFieldPrivate {
 impl Operation for PushClassFieldPrivate {
     const NAME: &'static str = "PushClassFieldPrivate";
     const INSTRUCTION: &'static str = "INST - PushClassFieldPrivate";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/push/class/mod.rs

@@ -22,6 +22,7 @@ pub(crate) struct PushClassPrototype;
 impl Operation for PushClassPrototype {
     const NAME: &'static str = "PushClassPrototype";
     const INSTRUCTION: &'static str = "INST - PushClassPrototype";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let superclass = context.vm.pop();

boa_engine/src/vm/opcode/push/class/private.rs

@@ -51,6 +51,7 @@ impl PushClassPrivateMethod {
 impl Operation for PushClassPrivateMethod {
     const NAME: &'static str = "PushClassPrivateMethod";
     const INSTRUCTION: &'static str = "INST - PushClassPrivateMethod";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -103,6 +104,7 @@ impl PushClassPrivateGetter {
 impl Operation for PushClassPrivateGetter {
     const NAME: &'static str = "PushClassPrivateGetter";
     const INSTRUCTION: &'static str = "INST - PushClassPrivateGetter";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -155,6 +157,7 @@ impl PushClassPrivateSetter {
 impl Operation for PushClassPrivateSetter {
     const NAME: &'static str = "PushClassPrivateSetter";
     const INSTRUCTION: &'static str = "INST - PushClassPrivateSetter";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/push/environment.rs

@@ -28,6 +28,7 @@ impl PushDeclarativeEnvironment {
 impl Operation for PushDeclarativeEnvironment {
     const NAME: &'static str = "PushDeclarativeEnvironment";
     const INSTRUCTION: &'static str = "INST - PushDeclarativeEnvironment";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let compile_environments_index = context.vm.read::<u8>() as usize;
@@ -55,6 +56,7 @@ pub(crate) struct PushObjectEnvironment;
 impl Operation for PushObjectEnvironment {
     const NAME: &'static str = "PushObjectEnvironment";
     const INSTRUCTION: &'static str = "INST - PushObjectEnvironment";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let object = context.vm.pop();
@@ -75,6 +77,7 @@ pub(crate) struct PushPrivateEnvironment;
 impl Operation for PushPrivateEnvironment {
     const NAME: &'static str = "PushPrivateEnvironment";
     const INSTRUCTION: &'static str = "INST - PushPrivateEnvironment";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let class_value = context.vm.pop();
@@ -114,6 +117,7 @@ pub(crate) struct PopPrivateEnvironment;
 impl Operation for PopPrivateEnvironment {
     const NAME: &'static str = "PopPrivateEnvironment";
     const INSTRUCTION: &'static str = "INST - PopPrivateEnvironment";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         context.vm.environments.pop_private();

boa_engine/src/vm/opcode/push/literal.rs

@@ -23,6 +23,7 @@ impl PushLiteral {
 impl Operation for PushLiteral {
     const NAME: &'static str = "PushLiteral";
     const INSTRUCTION: &'static str = "INST - PushLiteral";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -65,6 +66,7 @@ impl PushRegExp {
 impl Operation for PushRegExp {
     const NAME: &'static str = "PushRegExp";
     const INSTRUCTION: &'static str = "INST - PushRegExp";
+    const COST: u8 = 5;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let pattern_index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/push/mod.rs

@@ -29,6 +29,7 @@ macro_rules! implement_push_generics {
         impl Operation for $name {
             const NAME: &'static str = stringify!($name);
             const INSTRUCTION: &'static str = stringify!("INST - " + $name);
+            const COST: u8 = 1;
 
             fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
                 context.vm.push($push_value);

boa_engine/src/vm/opcode/push/numbers.rs

@@ -15,6 +15,7 @@ macro_rules! implement_push_numbers_with_conversion {
         impl Operation for $name {
             const NAME: &'static str = stringify!($name);
             const INSTRUCTION: &'static str = stringify!("INST - " + $name);
+            const COST: u8 = 1;
 
             fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
                 let value = context.vm.read::<$num_type>();
@@ -37,6 +38,7 @@ macro_rules! implement_push_numbers_no_conversion {
         impl Operation for $name {
             const NAME: &'static str = stringify!($name);
             const INSTRUCTION: &'static str = stringify!("INST - " + $name);
+            const COST: u8 = 1;
 
             fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
                 let value = context.vm.read::<$num_type>();

boa_engine/src/vm/opcode/push/object.rs

@@ -14,6 +14,7 @@ pub(crate) struct PushEmptyObject;
 impl Operation for PushEmptyObject {
     const NAME: &'static str = "PushEmptyObject";
     const INSTRUCTION: &'static str = "INST - PushEmptyObject";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let o = context

boa_engine/src/vm/opcode/require/mod.rs

@@ -13,6 +13,7 @@ pub(crate) struct RequireObjectCoercible;
 impl Operation for RequireObjectCoercible {
     const NAME: &'static str = "RequireObjectCoercible";
     const INSTRUCTION: &'static str = "INST - RequireObjectCoercible";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/rest_parameter/mod.rs

@@ -14,6 +14,7 @@ pub(crate) struct RestParameterInit;
 impl Operation for RestParameterInit {
     const NAME: &'static str = "RestParameterInit";
     const INSTRUCTION: &'static str = "INST - RestParameterInit";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let arg_count = context.vm.frame().argument_count as usize;

boa_engine/src/vm/opcode/set/class_prototype.rs

@@ -15,6 +15,7 @@ pub(crate) struct SetClassPrototype;
 impl Operation for SetClassPrototype {
     const NAME: &'static str = "SetClassPrototype";
     const INSTRUCTION: &'static str = "INST - SetClassPrototype";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let prototype_value = context.vm.pop();

boa_engine/src/vm/opcode/set/home_object.rs

@@ -13,6 +13,7 @@ pub(crate) struct SetHomeObject;
 impl Operation for SetHomeObject {
     const NAME: &'static str = "SetHomeObject";
     const INSTRUCTION: &'static str = "INST - SetHomeObject";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let function = context.vm.pop();

boa_engine/src/vm/opcode/set/name.rs

@@ -27,6 +27,7 @@ impl ThrowMutateImmutable {
 impl Operation for ThrowMutateImmutable {
     const NAME: &'static str = "ThrowMutateImmutable";
     const INSTRUCTION: &'static str = "INST - ThrowMutateImmutable";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -73,6 +74,7 @@ impl SetName {
 impl Operation for SetName {
     const NAME: &'static str = "SetName";
     const INSTRUCTION: &'static str = "INST - SetName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -100,6 +102,7 @@ pub(crate) struct SetNameByLocator;
 impl Operation for SetNameByLocator {
     const NAME: &'static str = "SetNameByLocator";
     const INSTRUCTION: &'static str = "INST - SetNameByLocator";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let binding_locator = context

boa_engine/src/vm/opcode/set/private.rs

@@ -36,6 +36,7 @@ impl SetPrivateField {
 impl Operation for SetPrivateField {
     const NAME: &'static str = "SetPrivateField";
     const INSTRUCTION: &'static str = "INST - SetPrivateField";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -81,6 +82,7 @@ impl DefinePrivateField {
 impl Operation for DefinePrivateField {
     const NAME: &'static str = "DefinePrivateField";
     const INSTRUCTION: &'static str = "INST - DefinePrivateField";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -140,6 +142,7 @@ impl SetPrivateMethod {
 impl Operation for SetPrivateMethod {
     const NAME: &'static str = "SetPrivateMethod";
     const INSTRUCTION: &'static str = "INST - SetPrivateMethod";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -190,6 +193,7 @@ impl SetPrivateSetter {
 impl Operation for SetPrivateSetter {
     const NAME: &'static str = "SetPrivateSetter";
     const INSTRUCTION: &'static str = "INST - SetPrivateSetter";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -240,6 +244,7 @@ impl SetPrivateGetter {
 impl Operation for SetPrivateGetter {
     const NAME: &'static str = "SetPrivateGetter";
     const INSTRUCTION: &'static str = "INST - SetPrivateGetter";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/set/property.rs

@@ -41,6 +41,7 @@ impl SetPropertyByName {
 impl Operation for SetPropertyByName {
     const NAME: &'static str = "SetPropertyByName";
     const INSTRUCTION: &'static str = "INST - SetPropertyByName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>();
@@ -68,6 +69,7 @@ pub(crate) struct SetPropertyByValue;
 impl Operation for SetPropertyByValue {
     const NAME: &'static str = "SetPropertyByValue";
     const INSTRUCTION: &'static str = "INST - SetPropertyByValue";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -197,6 +199,7 @@ impl SetPropertyGetterByName {
 impl Operation for SetPropertyGetterByName {
     const NAME: &'static str = "SetPropertyGetterByName";
     const INSTRUCTION: &'static str = "INST - SetPropertyGetterByName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -224,6 +227,7 @@ pub(crate) struct SetPropertyGetterByValue;
 impl Operation for SetPropertyGetterByValue {
     const NAME: &'static str = "SetPropertyGetterByValue";
     const INSTRUCTION: &'static str = "INST - SetPropertyGetterByValue";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -285,6 +289,7 @@ impl SetPropertySetterByName {
 impl Operation for SetPropertySetterByName {
     const NAME: &'static str = "SetPropertySetterByName";
     const INSTRUCTION: &'static str = "INST - SetPropertySetterByName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u8>() as usize;
@@ -312,6 +317,7 @@ pub(crate) struct SetPropertySetterByValue;
 impl Operation for SetPropertySetterByValue {
     const NAME: &'static str = "SetPropertySetterByValue";
     const INSTRUCTION: &'static str = "INST - SetPropertySetterByValue";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -348,6 +354,7 @@ pub(crate) struct SetFunctionName;
 impl Operation for SetFunctionName {
     const NAME: &'static str = "SetFunctionName";
     const INSTRUCTION: &'static str = "INST - SetFunctionName";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let prefix = context.vm.read::<u8>();

boa_engine/src/vm/opcode/set/prototype.rs

@@ -13,6 +13,7 @@ pub(crate) struct SetPrototype;
 impl Operation for SetPrototype {
     const NAME: &'static str = "SetPrototype";
     const INSTRUCTION: &'static str = "INST - SetPrototype";
+    const COST: u8 = 4;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/swap/mod.rs

@@ -13,6 +13,7 @@ pub(crate) struct Swap;
 impl Operation for Swap {
     const NAME: &'static str = "Swap";
     const INSTRUCTION: &'static str = "INST - Swap";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let len = context.vm.stack.len();
@@ -32,6 +33,7 @@ pub(crate) struct RotateLeft;
 impl Operation for RotateLeft {
     const NAME: &'static str = "RotateLeft";
     const INSTRUCTION: &'static str = "INST - RotateLeft";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let n = context.vm.read::<u8>() as usize;
@@ -51,6 +53,7 @@ pub(crate) struct RotateRight;
 impl Operation for RotateRight {
     const NAME: &'static str = "RotateRight";
     const INSTRUCTION: &'static str = "INST - RotateRight";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let n = context.vm.read::<u8>() as usize;

boa_engine/src/vm/opcode/switch/mod.rs

@@ -14,6 +14,7 @@ pub(crate) struct Case;
 impl Operation for Case {
     const NAME: &'static str = "Case";
     const INSTRUCTION: &'static str = "INST - Case";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let address = context.vm.read::<u32>();
@@ -39,6 +40,7 @@ pub(crate) struct Default;
 impl Operation for Default {
     const NAME: &'static str = "Default";
     const INSTRUCTION: &'static str = "INST - Default";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let exit = context.vm.read::<u32>();

boa_engine/src/vm/opcode/templates/mod.rs

@@ -17,6 +17,7 @@ pub(crate) struct TemplateLookup;
 impl Operation for TemplateLookup {
     const NAME: &'static str = "TemplateLookup";
     const INSTRUCTION: &'static str = "INST - TemplateLookup";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let jump = context.vm.read::<u32>();
@@ -101,6 +102,7 @@ impl TemplateCreate {
 impl Operation for TemplateCreate {
     const NAME: &'static str = "TemplateCreate";
     const INSTRUCTION: &'static str = "INST - TemplateCreate";
+    const COST: u8 = 6;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let count = u32::from(context.vm.read::<u8>());

boa_engine/src/vm/opcode/to/mod.rs

@@ -13,6 +13,7 @@ pub(crate) struct ToBoolean;
 impl Operation for ToBoolean {
     const NAME: &'static str = "ToBoolean";
     const INSTRUCTION: &'static str = "INST - ToBoolean";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -31,6 +32,7 @@ pub(crate) struct ToPropertyKey;
 impl Operation for ToPropertyKey {
     const NAME: &'static str = "ToPropertyKey";
     const INSTRUCTION: &'static str = "INST - ToPropertyKey";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/unary_ops/decrement.rs

@@ -14,6 +14,7 @@ pub(crate) struct Dec;
 impl Operation for Dec {
     const NAME: &'static str = "Dec";
     const INSTRUCTION: &'static str = "INST - Dec";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -42,6 +43,7 @@ pub(crate) struct DecPost;
 impl Operation for DecPost {
     const NAME: &'static str = "DecPost";
     const INSTRUCTION: &'static str = "INST - DecPost";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/unary_ops/increment.rs

@@ -14,6 +14,7 @@ pub(crate) struct Inc;
 impl Operation for Inc {
     const NAME: &'static str = "Inc";
     const INSTRUCTION: &'static str = "INST - Inc";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -42,6 +43,7 @@ pub(crate) struct IncPost;
 impl Operation for IncPost {
     const NAME: &'static str = "IncPost";
     const INSTRUCTION: &'static str = "INST - IncPost";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/unary_ops/logical.rs

@@ -13,6 +13,7 @@ pub(crate) struct LogicalNot;
 impl Operation for LogicalNot {
     const NAME: &'static str = "LogicalNot";
     const INSTRUCTION: &'static str = "INST - LogicalNot";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/unary_ops/mod.rs

@@ -26,6 +26,7 @@ pub(crate) struct TypeOf;
 impl Operation for TypeOf {
     const NAME: &'static str = "TypeOf";
     const INSTRUCTION: &'static str = "INST - TypeOf";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -44,6 +45,7 @@ pub(crate) struct Pos;
 impl Operation for Pos {
     const NAME: &'static str = "Pos";
     const INSTRUCTION: &'static str = "INST - Pos";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -63,6 +65,7 @@ pub(crate) struct Neg;
 impl Operation for Neg {
     const NAME: &'static str = "Neg";
     const INSTRUCTION: &'static str = "INST - Neg";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -84,6 +87,7 @@ pub(crate) struct BitNot;
 impl Operation for BitNot {
     const NAME: &'static str = "BitNot";
     const INSTRUCTION: &'static str = "INST - BitNot";
+    const COST: u8 = 3;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();

boa_engine/src/vm/opcode/unary_ops/void.rs

@@ -13,6 +13,7 @@ pub(crate) struct Void;
 impl Operation for Void {
     const NAME: &'static str = "Void";
     const INSTRUCTION: &'static str = "INST - Void";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let _old = context.vm.pop();

boa_engine/src/vm/opcode/value/mod.rs

@@ -14,6 +14,7 @@ pub(crate) struct ValueNotNullOrUndefined;
 impl Operation for ValueNotNullOrUndefined {
     const NAME: &'static str = "ValueNotNullOrUndefined";
     const INSTRUCTION: &'static str = "INST - ValueNotNullOrUndefined";
+    const COST: u8 = 2;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
@@ -42,6 +43,7 @@ pub(crate) struct IsObject;
 impl Operation for IsObject {
     const NAME: &'static str = "IsObject";
     const INSTRUCTION: &'static str = "INST - IsObject";
+    const COST: u8 = 1;
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();