Use main stack for calling

- Move `return_value` to stack

boa_engine/src/builtins/eval/mod.rs

@@ -258,6 +258,9 @@ impl Eval {
             .vm
             .push_frame(CallFrame::new(code_block).with_env_fp(env_fp));
         context.realm().resize_global_env();
+
+        // Push return value.
+        context.vm.push(JsValue::undefined());
         let record = context.run();
         context.vm.pop_frame();
 

boa_engine/src/builtins/generator/mod.rs

@@ -85,13 +85,18 @@ impl GeneratorContext {
 
     /// Creates a new `GeneratorContext` from the current `Context` state.
     pub(crate) fn from_current(context: &mut Context<'_>) -> Self {
-        Self {
+        let fp = context.vm.frame().fp as usize;
+        let this = Self {
             environments: context.vm.environments.clone(),
             call_frame: Some(context.vm.frame().clone()),
-            stack: context.vm.stack.clone(),
+            stack: context.vm.stack[fp..].to_vec(),
             active_function: context.vm.active_function.clone(),
             realm: context.realm().clone(),
-        }
+        };
+
+        context.vm.stack.truncate(fp);
+
+        this
     }
 
     /// Resumes execution with `GeneratorContext` as the current execution context.
@@ -109,6 +114,8 @@ impl GeneratorContext {
             .vm
             .push_frame(self.call_frame.take().expect("should have a call frame"));
 
+        context.vm.frame_mut().fp = 0;
+
         if let Some(value) = value {
             context.vm.push(value);
         }

boa_engine/src/builtins/json/mod.rs

@@ -133,6 +133,8 @@ impl Json {
             .vm
             .push_frame(CallFrame::new(code_block).with_env_fp(env_fp));
         context.realm().resize_global_env();
+        // Push return value.
+        context.vm.push(JsValue::undefined());
         let record = context.run();
         context.vm.pop_frame();
 

boa_engine/src/bytecompiler/mod.rs

@@ -300,7 +300,10 @@ impl<'ctx, 'host> ByteCompiler<'ctx, 'host> {
             params: FormalParameterList::default(),
             compile_environments: Vec::default(),
             current_open_environments_count: 0,
-            current_stack_value_count: 0,
+
+            // Note: We set it to one so we don't pop return value,
+            // which is allocated after frame pointer.
+            current_stack_value_count: 1,
             code_block_flags,
             handlers: ThinVec::default(),
 

boa_engine/src/module/source.rs

@@ -1763,6 +1763,9 @@ impl SourceTextModule {
         // 10. Else,
         //    a. Assert: capability is a PromiseCapability Record.
         //    b. Perform AsyncBlockStart(capability, module.[[ECMAScriptCode]], moduleContext).
+
+        // Push return value.
+        context.vm.push(JsValue::undefined());
         let result = context.run();
 
         std::mem::swap(&mut context.vm.environments, &mut environments);

boa_engine/src/script.rs

@@ -150,6 +150,9 @@ impl Script {
 
         // TODO: Here should be https://tc39.es/ecma262/#sec-globaldeclarationinstantiation
 
+        // Push return value.
+        context.vm.push(JsValue::undefined());
+
         self.realm().resize_global_env();
         let record = context.run();
         context.vm.pop_frame();

boa_engine/src/vm/call_frame/mod.rs

@@ -36,11 +36,6 @@ pub struct CallFrame {
 
     /// How many iterations a loop has done.
     pub(crate) loop_iteration_count: u64,
-
-    /// The value that is returned from the function.
-    //
-    // TODO(HalidOdat): Remove this and put into the stack, maybe before frame pointer.
-    pub(crate) return_value: JsValue,
 }
 
 /// ---- `CallFrame` public API ----
@@ -68,7 +63,6 @@ impl CallFrame {
             iterators: ThinVec::new(),
             binding_stack: Vec::new(),
             loop_iteration_count: 0,
-            return_value: JsValue::undefined(),
         }
     }
 

boa_engine/src/vm/code_block.rs

@@ -1231,22 +1231,7 @@ impl JsObject {
         }
 
         let argument_count = args.len();
-
-        // Push function arguments to the stack.
-        let mut args = if code.params.as_ref().len() > args.len() {
-            let mut v = args.to_vec();
-            v.extend(vec![
-                JsValue::Undefined;
-                code.params.as_ref().len() - args.len()
-            ]);
-            v
-        } else {
-            args.to_vec()
-        };
-        args.reverse();
-        let mut stack = args;
-
-        std::mem::swap(&mut context.vm.stack, &mut stack);
+        let parameters_count = code.params.as_ref().len();
 
         let frame = CallFrame::new(code)
             .with_argument_count(argument_count as u32)
@@ -1256,14 +1241,22 @@ impl JsObject {
 
         context.vm.push_frame(frame);
 
+        // Push return value.
+        context.vm.push(JsValue::undefined());
+
+        // Push function arguments to the stack.
+        for _ in argument_count..parameters_count {
+            context.vm.push(JsValue::undefined());
+        }
+        context.vm.stack.extend(args.iter().rev().cloned());
+
         let result = context
             .run()
             .consume()
             .map_err(|err| err.inject_realm(context.realm().clone()));
 
         context.vm.pop_frame().expect("frame must exist");
         std::mem::swap(&mut environments, &mut context.vm.environments);
-        std::mem::swap(&mut context.vm.stack, &mut stack);
         std::mem::swap(&mut context.vm.active_runnable, &mut script_or_module);
 
         result
@@ -1438,22 +1431,7 @@ impl JsObject {
                 }
 
                 let argument_count = args.len();
-
-                // Push function arguments to the stack.
-                let args = if code.params.as_ref().len() > args.len() {
-                    let mut v = args.to_vec();
-                    v.extend(vec![
-                        JsValue::Undefined;
-                        code.params.as_ref().len() - args.len()
-                    ]);
-                    v
-                } else {
-                    args.to_vec()
-                };
-
-                for arg in args.iter().rev() {
-                    context.vm.push(arg.clone());
-                }
+                let parameters_count = code.params.as_ref().len();
 
                 let has_binding_identifier = code.has_binding_identifier();
 
@@ -1465,6 +1443,15 @@ impl JsObject {
                         .with_env_fp(environments_len as u32),
                 );
 
+                // Push return value.
+                context.vm.push(JsValue::undefined());
+
+                // Push function arguments to the stack.
+                for _ in argument_count..parameters_count {
+                    context.vm.push(JsValue::undefined());
+                }
+                context.vm.stack.extend(args.iter().rev().cloned());
+
                 let record = context.run();
 
                 context.vm.pop_frame();

boa_engine/src/vm/mod.rs

@@ -181,6 +181,16 @@ impl Vm {
 
         true
     }
+
+    pub(crate) fn get_return_value(&self) -> JsValue {
+        let fp = self.frame().fp;
+        self.stack[fp as usize].clone()
+    }
+
+    pub(crate) fn set_return_value(&mut self, value: JsValue) {
+        let fp = self.frame().fp;
+        self.stack[fp as usize] = value;
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq)]
@@ -328,8 +338,8 @@ impl Context<'_> {
             match result {
                 Ok(CompletionType::Normal) => {}
                 Ok(CompletionType::Return) => {
+                    let execution_result = self.vm.get_return_value();
                     self.vm.stack.truncate(self.vm.frame().fp as usize);
-                    let execution_result = self.vm.frame_mut().return_value.clone();
                     return CompletionRecord::Normal(execution_result);
                 }
                 Ok(CompletionType::Throw) => {

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

@@ -189,14 +189,16 @@ impl Operation for CompletePromiseCapability {
                 .call(&JsValue::undefined(), &[error.to_opaque(context)], context)
                 .expect("cannot fail per spec");
         } else {
-            let return_value = context.vm.frame().return_value.clone();
+            let return_value = context.vm.get_return_value();
             promise_capability
                 .resolve()
                 .call(&JsValue::undefined(), &[return_value], context)
                 .expect("cannot fail per spec");
         };
 
-        context.vm.frame_mut().return_value = promise_capability.promise().clone().into();
+        context
+            .vm
+            .set_return_value(promise_capability.promise().clone().into());
 
         Ok(CompletionType::Normal)
     }

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

@@ -31,7 +31,7 @@ impl Operation for GetReturnValue {
     const INSTRUCTION: &'static str = "INST - GetReturnValue";
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
-        let value = context.vm.frame().return_value.clone();
+        let value = context.vm.get_return_value();
         context.vm.push(value);
         Ok(CompletionType::Normal)
     }
@@ -50,7 +50,7 @@ impl Operation for SetReturnValue {
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let value = context.vm.pop();
-        context.vm.frame_mut().return_value = value;
+        context.vm.set_return_value(value);
         Ok(CompletionType::Normal)
     }
 }

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

@@ -16,7 +16,7 @@ use crate::{
         opcode::{Operation, ReThrow},
         CallFrame, CompletionType,
     },
-    Context, JsError, JsObject, JsResult,
+    Context, JsError, JsObject, JsResult, JsValue,
 };
 
 pub(crate) use yield_stm::*;
@@ -41,7 +41,14 @@ impl Operation for Generator {
         let pc = context.vm.frame().pc;
         let mut dummy_call_frame = CallFrame::new(code_block);
         dummy_call_frame.pc = pc;
-        let call_frame = std::mem::replace(context.vm.frame_mut(), dummy_call_frame);
+        let mut call_frame = std::mem::replace(context.vm.frame_mut(), dummy_call_frame);
+
+        let fp = call_frame.fp as usize;
+
+        let stack = context.vm.stack[fp..].to_vec();
+        context.vm.stack.truncate(fp);
+
+        call_frame.fp = 0;
 
         let this_function_object = context
             .vm
@@ -69,7 +76,6 @@ impl Operation for Generator {
             &mut context.vm.environments,
             EnvironmentStack::new(global_environement),
         );
-        let stack = std::mem::take(&mut context.vm.stack);
 
         let data = if r#async {
             ObjectData::async_generator(AsyncGenerator {
@@ -154,7 +160,8 @@ impl Operation for AsyncGeneratorClose {
             .expect("must have item in queue");
         drop(generator_object_mut);
 
-        let return_value = std::mem::take(&mut context.vm.frame_mut().return_value);
+        let return_value = context.vm.get_return_value();
+        context.vm.set_return_value(JsValue::undefined());
 
         if let Some(error) = context.vm.pending_exception.take() {
             AsyncGenerator::complete_step(&next, Err(error), true, None, context);