Refactor registers to use the stack

core/engine/src/builtins/eval/mod.rs

@@ -20,7 +20,7 @@ use crate::{
     realm::Realm,
     spanned_source_text::SourceText,
     string::StaticJsStrings,
-    vm::{CallFrame, CallFrameFlags, Constant, Registers},
+    vm::{CallFrame, CallFrameFlags, Constant},
     Context, JsArgs, JsResult, JsString, JsValue, SpannedSourceText,
 };
 use boa_ast::{
@@ -333,8 +333,7 @@ impl Eval {
 
         context.realm().resize_global_env();
 
-        let register_count = context.vm.frame().code_block().register_count;
-        let record = context.run(&mut Registers::new(register_count as usize));
+        let record = context.run();
         context.vm.pop_frame();
 
         record.consume()

core/engine/src/builtins/function/bound.rs

@@ -109,23 +109,28 @@ fn bound_function_exotic_call(
         .downcast_ref::<BoundFunction>()
         .expect("bound function exotic method should only be callable from bound function objects");
 
-    let arguments_start_index = context.vm.stack.len() - argument_count;
-
     // 1. Let target be F.[[BoundTargetFunction]].
     let target = bound_function.target_function();
-    context.vm.stack[arguments_start_index - 1] = target.clone().into();
+    context
+        .vm
+        .stack
+        .calling_convention_set_function(argument_count, target.clone().into());
 
     // 2. Let boundThis be F.[[BoundThis]].
     let bound_this = bound_function.this();
-    context.vm.stack[arguments_start_index - 2] = bound_this.clone();
+    context
+        .vm
+        .stack
+        .calling_convention_set_this(argument_count, bound_this.clone());
 
     // 3. Let boundArgs be F.[[BoundArguments]].
     let bound_args = bound_function.args();
 
     // 4. Let args be the list-concatenation of boundArgs and argumentsList.
     context
         .vm
-        .insert_values_at(bound_args, arguments_start_index);
+        .stack
+        .calling_convention_insert_arguments(argument_count, bound_args);
 
     // 5. Return ? Call(target, boundThis, args).
     Ok(target.__call__(bound_args.len() + argument_count))
@@ -143,7 +148,7 @@ fn bound_function_exotic_construct(
     argument_count: usize,
     context: &mut Context,
 ) -> JsResult<CallValue> {
-    let new_target = context.vm.pop();
+    let new_target = context.vm.stack.pop();
 
     debug_assert!(new_target.is_object(), "new.target should be an object");
 
@@ -160,10 +165,10 @@ fn bound_function_exotic_construct(
     let bound_args = bound_function.args();
 
     // 4. Let args be the list-concatenation of boundArgs and argumentsList.
-    let arguments_start_index = context.vm.stack.len() - argument_count;
     context
         .vm
-        .insert_values_at(bound_args, arguments_start_index);
+        .stack
+        .calling_convention_insert_arguments(argument_count, bound_args);
 
     // 5. If SameValue(F, newTarget) is true, set newTarget to target.
     let function_object: JsValue = function_object.clone().into();
@@ -174,6 +179,6 @@ fn bound_function_exotic_construct(
     };
 
     // 6. Return ? Construct(target, args, newTarget).
-    context.vm.push(new_target);
+    context.vm.stack.push(new_target);
     Ok(target.__construct__(bound_args.len() + argument_count))
 }

core/engine/src/builtins/function/mod.rs

@@ -995,7 +995,6 @@ pub(crate) fn function_call(
     let code = function.code.clone();
     let environments = function.environments.clone();
     let script_or_module = function.script_or_module.clone();
-    let register_count = code.register_count as usize;
 
     drop(function);
 
@@ -1007,7 +1006,7 @@ pub(crate) fn function_call(
 
     context.vm.push_frame(frame);
 
-    let this = context.vm.frame().this(&context.vm);
+    let this = context.vm.stack.get_this(context.vm.frame());
 
     let lexical_this_mode = code.this_mode == ThisMode::Lexical;
 
@@ -1044,7 +1043,7 @@ pub(crate) fn function_call(
         );
     }
 
-    Ok(CallValue::Ready { register_count })
+    Ok(CallValue::Ready)
 }
 
 /// Construct an instance of this object with the specified arguments.
@@ -1073,12 +1072,11 @@ fn function_construct(
     let code = function.code.clone();
     let environments = function.environments.clone();
     let script_or_module = function.script_or_module.clone();
-    let register_count = code.register_count as usize;
     drop(function);
 
     let env_fp = environments.len() as u32;
 
-    let new_target = context.vm.pop();
+    let new_target = context.vm.stack.pop();
 
     let this = if code.is_derived_constructor() {
         None
@@ -1111,13 +1109,8 @@ fn function_construct(
         .flags
         .set(CallFrameFlags::THIS_VALUE_CACHED, this.is_some());
 
-    let len = context.vm.stack.len();
-
     context.vm.push_frame(frame);
 
-    // NOTE(HalidOdat): +1 because we insert `this` value below.
-    context.vm.frame_mut().rp = len as u32 + 1;
-
     let mut last_env = 0;
 
     if code.has_binding_identifier() {
@@ -1146,11 +1139,10 @@ fn function_construct(
         ),
     );
 
-    // Insert `this` value
-    context.vm.stack.insert(
-        len - argument_count - 1,
+    context.vm.stack.set_this(
+        &context.vm.frame,
         this.map(JsValue::new).unwrap_or_default(),
     );
 
-    Ok(CallValue::Ready { register_count })
+    Ok(CallValue::Ready)
 }

core/engine/src/builtins/generator/mod.rs

@@ -20,7 +20,7 @@ use crate::{
     string::StaticJsStrings,
     symbol::JsSymbol,
     value::JsValue,
-    vm::{CallFrame, CallFrameFlags, CompletionRecord, GeneratorResumeKind, Registers},
+    vm::{CallFrame, CallFrameFlags, CompletionRecord, GeneratorResumeKind, Stack},
     Context, JsArgs, JsData, JsError, JsResult, JsString,
 };
 use boa_gc::{custom_trace, Finalize, Trace};
@@ -59,23 +59,17 @@ unsafe impl Trace for GeneratorState {
 /// context/vm before the generator execution starts/resumes and after it has ended/yielded.
 #[derive(Debug, Trace, Finalize)]
 pub(crate) struct GeneratorContext {
-    pub(crate) stack: Vec<JsValue>,
+    pub(crate) stack: Stack,
     pub(crate) call_frame: Option<CallFrame>,
-    registers: Registers,
 }
 
 impl GeneratorContext {
     /// Creates a new `GeneratorContext` from the current `Context` state.
-    pub(crate) fn from_current(
-        context: &mut Context,
-        mut registers: Registers,
-        async_generator: Option<JsObject>,
-    ) -> Self {
+    pub(crate) fn from_current(context: &mut Context, async_generator: Option<JsObject>) -> Self {
         let mut frame = context.vm.frame().clone();
         frame.environments = context.vm.environments.clone();
         frame.realm = context.realm().clone();
-        let fp = frame.fp() as usize;
-        let stack = context.vm.stack.split_off(fp);
+        let mut stack = context.vm.stack.split_off_frame(&frame);
 
         frame.rp = CallFrame::FUNCTION_PROLOGUE + frame.argument_count;
 
@@ -84,16 +78,12 @@ impl GeneratorContext {
         frame.flags |= CallFrameFlags::REGISTERS_ALREADY_PUSHED;
 
         if let Some(async_generator) = async_generator {
-            registers.set(
-                CallFrame::ASYNC_GENERATOR_OBJECT_REGISTER_INDEX,
-                async_generator.into(),
-            );
+            stack.set_async_generator_object(&frame, async_generator);
         }
 
         Self {
             call_frame: Some(frame),
             stack,
-            registers,
         }
     }
 
@@ -114,11 +104,11 @@ impl GeneratorContext {
         frame.set_exit_early(true);
 
         if let Some(value) = value {
-            context.vm.push(value);
+            context.vm.stack.push(value);
         }
-        context.vm.push(resume_kind);
+        context.vm.stack.push(resume_kind);
 
-        let result = context.run(&mut self.registers);
+        let result = context.run();
 
         std::mem::swap(&mut context.vm.stack, &mut self.stack);
         self.call_frame = context.vm.pop_frame();
@@ -128,9 +118,10 @@ impl GeneratorContext {
 
     /// Returns the async generator object, if the function that this [`GeneratorContext`] is from an async generator, [`None`] otherwise.
     pub(crate) fn async_generator_object(&self) -> Option<JsObject> {
-        self.call_frame
-            .as_ref()
-            .and_then(|frame| frame.async_generator_object(&self.registers))
+        if let Some(frame) = &self.call_frame {
+            return self.stack.async_generator_object(frame);
+        }
+        None
     }
 }
 

core/engine/src/builtins/intl/number_format/mod.rs

@@ -410,7 +410,7 @@ impl BuiltInConstructor for NumberFormat {
         // ChainNumberFormat ( numberFormat, newTarget, this )
         // <https://tc39.es/ecma402/#sec-chainnumberformat>
 
-        let this = context.vm.frame().this(&context.vm);
+        let this = context.vm.stack.get_this(context.vm.frame());
         let Some(this_obj) = this.as_object() else {
             return Ok(number_format.into());
         };

core/engine/src/builtins/json/mod.rs

@@ -31,7 +31,7 @@ use crate::{
     string::{CodePoint, StaticJsStrings},
     symbol::JsSymbol,
     value::IntegerOrInfinity,
-    vm::{CallFrame, CallFrameFlags, Registers},
+    vm::{CallFrame, CallFrameFlags},
     Context, JsArgs, JsBigInt, JsResult, JsString, JsValue, SpannedSourceText,
 };
 use boa_gc::Gc;
@@ -147,8 +147,7 @@ impl Json {
         );
 
         context.realm().resize_global_env();
-        let register_count = context.vm.frame().code_block().register_count;
-        let record = context.run(&mut Registers::new(register_count as usize));
+        let record = context.run();
         context.vm.pop_frame();
 
         let unfiltered = record.consume()?;

core/engine/src/builtins/proxy/mod.rs

@@ -1165,21 +1165,24 @@ fn proxy_exotic_call(
         return Ok(target.__call__(argument_count));
     };
 
-    let args = context.vm.pop_n_values(argument_count);
+    let args = context
+        .vm
+        .stack
+        .calling_convention_pop_arguments(argument_count);
 
     // 7. Let argArray be ! CreateArrayFromList(argumentsList).
     let arg_array = array::Array::create_array_from_list(args, context);
 
     // 8. Return ? Call(trap, handler, « target, thisArgument, argArray »).
-    let _func = context.vm.pop();
-    let this = context.vm.pop();
+    let _func = context.vm.stack.pop();
+    let this = context.vm.stack.pop();
 
-    context.vm.push(handler); // This
-    context.vm.push(trap.clone()); // Function
+    context.vm.stack.push(handler); // This
+    context.vm.stack.push(trap.clone()); // Function
 
-    context.vm.push(target);
-    context.vm.push(this);
-    context.vm.push(arg_array);
+    context.vm.stack.push(target);
+    context.vm.stack.push(this);
+    context.vm.stack.push(arg_array);
     Ok(trap.__call__(3))
 }
 
@@ -1213,9 +1216,13 @@ fn proxy_exotic_construct(
         return Ok(target.__construct__(argument_count));
     };
 
-    let new_target = context.vm.pop();
-    let args = context.vm.pop_n_values(argument_count);
-    let _func = context.vm.pop();
+    let new_target = context.vm.stack.pop();
+    let args = context
+        .vm
+        .stack
+        .calling_convention_pop_arguments(argument_count);
+    let _func = context.vm.stack.pop();
+    let _this = context.vm.stack.pop();
 
     // 8. Let argArray be ! CreateArrayFromList(argumentsList).
     let arg_array = array::Array::create_array_from_list(args, context);
@@ -1233,6 +1240,6 @@ fn proxy_exotic_construct(
     })?;
 
     // 11. Return newObj.
-    context.vm.push(new_obj);
+    context.vm.stack.push(new_obj);
     Ok(CallValue::Complete)
 }

core/engine/src/bytecompiler/expression/mod.rs

@@ -351,9 +351,13 @@ impl ByteCompiler<'_> {
                 self.compile_class(class.deref().into(), Some(dst));
             }
             Expression::SuperCall(super_call) => {
+                let this = self.register_allocator.alloc();
                 let value = self.register_allocator.alloc();
                 self.bytecode.emit_super_call_prepare(value.variable());
+                self.bytecode.emit_push_undefined(this.variable());
+                self.push_from_register(&this);
                 self.push_from_register(&value);
+                self.register_allocator.dealloc(this);
                 self.register_allocator.dealloc(value);
 
                 let contains_spread = super_call

core/engine/src/bytecompiler/mod.rs

@@ -511,22 +511,22 @@ impl<'ctx> ByteCompiler<'ctx> {
 
             debug_assert_eq!(
                 promise_register.index(),
-                CallFrame::PROMISE_CAPABILITY_PROMISE_REGISTER_INDEX
+                CallFrame::PROMISE_CAPABILITY_PROMISE_REGISTER_INDEX as u32
             );
             debug_assert_eq!(
                 resolve_register.index(),
-                CallFrame::PROMISE_CAPABILITY_RESOLVE_REGISTER_INDEX
+                CallFrame::PROMISE_CAPABILITY_RESOLVE_REGISTER_INDEX as u32
             );
             debug_assert_eq!(
                 reject_register.index(),
-                CallFrame::PROMISE_CAPABILITY_REJECT_REGISTER_INDEX
+                CallFrame::PROMISE_CAPABILITY_REJECT_REGISTER_INDEX as u32
             );
 
             if is_generator {
                 let async_function_object_register = register_allocator.alloc_persistent();
                 debug_assert_eq!(
                     async_function_object_register.index(),
-                    CallFrame::ASYNC_GENERATOR_OBJECT_REGISTER_INDEX
+                    CallFrame::ASYNC_GENERATOR_OBJECT_REGISTER_INDEX as u32
                 );
             }
         }
@@ -1833,7 +1833,6 @@ impl<'ctx> ByteCompiler<'ctx> {
                 self.register_allocator.dealloc(this);
                 self.register_allocator.dealloc(dst);
             }
-
             Expression::Optional(opt) if kind == CallKind::Call => {
                 let this = self.register_allocator.alloc();
                 let dst = self.register_allocator.alloc();
@@ -1883,9 +1882,13 @@ impl<'ctx> ByteCompiler<'ctx> {
                 self.register_allocator.dealloc(value);
             }
             expr => {
+                let this = self.register_allocator.alloc();
                 let value = self.register_allocator.alloc();
                 self.compile_expr(expr, &value);
+                self.bytecode.emit_push_undefined(this.variable());
+                self.push_from_register(&this);
                 self.push_from_register(&value);
+                self.register_allocator.dealloc(this);
                 self.register_allocator.dealloc(value);
             }
         }

core/engine/src/context/mod.rs

@@ -880,7 +880,7 @@ impl Context {
             return self.vm.native_active_function.clone();
         }
 
-        self.vm.frame.function(&self.vm)
+        self.vm.stack.get_function(self.vm.frame())
     }
 }