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Refactor vm calling convention to allow locals
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@HalidOdat
HalidOdat committed Dec 9, 2023
1 parent 0f82312 commit a7aea59
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Showing 9 changed files with 106 additions and 106 deletions.
20 changes: 9 additions & 11 deletions core/engine/src/builtins/function/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -938,10 +938,7 @@ pub(crate) fn function_call(

context.vm.push_frame(frame);

let fp = context.vm.stack.len() - argument_count - CallFrame::FUNCTION_PROLOGUE;
context.vm.frame_mut().fp = fp as u32;

let this = context.vm.stack[fp + CallFrame::THIS_POSITION].clone();
let this = context.vm.frame().this(&context.vm);

let lexical_this_mode = code.this_mode == ThisMode::Lexical;

Expand Down Expand Up @@ -1013,8 +1010,6 @@ fn function_construct(

let new_target = context.vm.pop();

let at = context.vm.stack.len() - argument_count;

let this = if code.is_derived_constructor() {
None
} else {
Expand Down Expand Up @@ -1042,7 +1037,10 @@ fn function_construct(

context.vm.push_frame(frame);

context.vm.frame_mut().fp = at as u32 - 1;
let len = context.vm.stack.len();

// NOTE(HalidOdat): +1 because we insert `this` value below.
context.vm.frame_mut().fp = len as u32 + 1;

let mut last_env = 0;

Expand Down Expand Up @@ -1075,10 +1073,10 @@ fn function_construct(
);

// Insert `this` value
context
.vm
.stack
.insert(at - 1, this.map(JsValue::new).unwrap_or_default());
context.vm.stack.insert(
len - argument_count - 1,
this.map(JsValue::new).unwrap_or_default(),
);

Ok(CallValue::Ready)
}
30 changes: 11 additions & 19 deletions core/engine/src/builtins/generator/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -64,28 +64,20 @@ pub(crate) struct GeneratorContext {
}

impl GeneratorContext {
/// Creates a new `GeneratorContext` from the raw `Context` state components.
pub(crate) fn new(stack: Vec<JsValue>, call_frame: CallFrame) -> Self {
Self {
stack,
call_frame: Some(call_frame),
}
}

/// Creates a new `GeneratorContext` from the current `Context` state.
pub(crate) fn from_current(context: &mut Context) -> Self {
let mut frame = context.vm.frame().clone();
frame.environments = context.vm.environments.clone();
frame.realm = context.realm().clone();
let fp = context.vm.frame().fp as usize;
let this = Self {
call_frame: Some(frame),
stack: context.vm.stack[fp..].to_vec(),
};
let fp = frame.restore_fp() as usize;
let stack = context.vm.stack.split_off(fp);

context.vm.stack.truncate(fp);
frame.fp = CallFrame::FUNCTION_PROLOGUE + frame.argument_count;

this
Self {
call_frame: Some(frame),
stack,
}
}

/// Resumes execution with `GeneratorContext` as the current execution context.
Expand All @@ -96,11 +88,11 @@ impl GeneratorContext {
context: &mut Context,
) -> CompletionRecord {
std::mem::swap(&mut context.vm.stack, &mut self.stack);
context
.vm
.push_frame(self.call_frame.take().expect("should have a call frame"));
let frame = self.call_frame.take().expect("should have a call frame");
let fp = frame.fp;
context.vm.push_frame(frame);

context.vm.frame_mut().fp = 0;
context.vm.frame_mut().fp = fp;
context.vm.frame_mut().set_exit_early(true);

if let Some(value) = value {
Expand Down
3 changes: 1 addition & 2 deletions core/engine/src/bytecompiler/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -327,8 +327,7 @@ impl<'ctx> ByteCompiler<'ctx> {
params: FormalParameterList::default(),
current_open_environments_count: 0,

// This starts at two because the first value is the `this` value, then function object.
current_stack_value_count: 2,
current_stack_value_count: 0,
code_block_flags,
handlers: ThinVec::default(),
ic: Vec::default(),
Expand Down
2 changes: 1 addition & 1 deletion core/engine/src/module/synthetic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -324,7 +324,7 @@ impl SyntheticModule {
// 11. Suspend moduleContext and remove it from the execution context stack.
// 12. Resume the context that is now on the top of the execution context stack as the running execution context.
let frame = context.vm.pop_frame().expect("there should be a frame");
context.vm.stack.truncate(frame.fp as usize);
frame.restore_stack(&mut context.vm);

// 13. Let pc be ! NewPromiseCapability(%Promise%).
let (promise, ResolvingFunctions { resolve, reject }) = JsPromise::new_pending(context);
Expand Down
80 changes: 63 additions & 17 deletions core/engine/src/vm/call_frame/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -81,22 +81,48 @@ impl CallFrame {
impl CallFrame {
/// This is the size of the function prologue.
///
/// The position of the elements are relative to the [`CallFrame::fp`].
/// The position of the elements are relative to the [`CallFrame::fp`] (frame pointer).
///
/// ```text
/// --- frame pointer arguments
/// / __________________________/
/// / / \
/// | 0: this | 1: func | 2: arg1 | ... | (2 + N): argN |
/// \ /
/// ------------
/// |
/// function prolugue
/// Setup by the caller
/// ┌─────────────────────────────────────────────────────────┐ ┌───── frame pointer
/// ▼ ▼ ▼
/// | -(2 + N): this | -(1 + N): func | -N: arg1 | ... | -1: argN | 0: local1 | ... | K: localK |
/// ▲ ▲ ▲ ▲ ▲ ▲
/// └──────────────────────────────┘ └──────────────────────┘ └─────────────────────────┘
/// function prolugue arguments Setup by the callee
/// ```
pub(crate) const FUNCTION_PROLOGUE: usize = 2;
pub(crate) const THIS_POSITION: usize = 0;
pub(crate) const FUNCTION_POSITION: usize = 1;
pub(crate) const FIRST_ARGUMENT_POSITION: usize = 2;
///
/// ### Example
///
/// The following function calls, generate the following stack:
///
/// ```JavaScript
/// function x(a) {
/// }
/// function y(b, c) {
/// return x(b + c)
/// }
///
/// y(1, 2)
/// ```
///
/// ```text
/// caller prolugue caller arguments callee prolugue callee arguments
/// ______|____________ _____|_____ _________|_________ __|_
/// / \ / \ / \ / \
/// | 0: undefined | 1: y | 2: 1 | 3: 2 | 4: undefined | 5: x | 6: 3 |
/// / ^
/// caller frame pointer --+ callee frame pointer
/// ```
///
/// Some questions:
///
/// - Who is responsible for cleaning up the stack after a call? The caller.
///
pub(crate) const FUNCTION_PROLOGUE: u32 = 2;
pub(crate) const THIS_POSITION: u32 = 2;
pub(crate) const FUNCTION_POSITION: u32 = 1;

/// Creates a new `CallFrame` with the provided `CodeBlock`.
pub(crate) fn new(
Expand Down Expand Up @@ -142,19 +168,39 @@ impl CallFrame {
}

pub(crate) fn this(&self, vm: &Vm) -> JsValue {
let this_index = self.fp as usize + Self::THIS_POSITION;
vm.stack[this_index].clone()
let this_index = self.fp - self.argument_count - Self::THIS_POSITION;
vm.stack[this_index as usize].clone()
}

pub(crate) fn function(&self, vm: &Vm) -> Option<JsObject> {
let function_index = self.fp as usize + Self::FUNCTION_POSITION;
if let Some(object) = vm.stack[function_index].as_object() {
let function_index = self.fp - self.argument_count - Self::FUNCTION_POSITION;
if let Some(object) = vm.stack[function_index as usize].as_object() {
return Some(object.clone());
}

None
}

pub(crate) fn arguments<'stack>(&self, vm: &'stack Vm) -> &'stack [JsValue] {
let fp = self.fp as usize;
let argument_count = self.argument_count as usize;
let arguments_start = fp - argument_count;
&vm.stack[arguments_start..fp]
}

pub(crate) fn argument<'stack>(&self, index: usize, vm: &'stack Vm) -> Option<&'stack JsValue> {
self.arguments(vm).get(index)
}

pub(crate) fn restore_fp(&self) -> u32 {
self.fp - self.argument_count - Self::FUNCTION_PROLOGUE
}

pub(crate) fn restore_stack(&self, vm: &mut Vm) {
let fp = self.restore_fp();
vm.stack.truncate(fp as usize);
}

/// Does this have the [`CallFrameFlags::EXIT_EARLY`] flag.
pub(crate) fn exit_early(&self) -> bool {
self.flags.contains(CallFrameFlags::EXIT_EARLY)
Expand Down
21 changes: 8 additions & 13 deletions core/engine/src/vm/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -167,20 +167,14 @@ impl Vm {

pub(crate) fn push_frame_with_stack(
&mut self,
mut frame: CallFrame,
frame: CallFrame,
this: JsValue,
function: JsValue,
) {
let current_stack_length = self.stack.len();
frame.set_frame_pointer(current_stack_length as u32);

self.push(this);
self.push(function);

std::mem::swap(&mut self.environments, &mut frame.environments);
std::mem::swap(&mut self.realm, &mut frame.realm);

self.frames.push(frame);
self.push_frame(frame);
}

pub(crate) fn pop_frame(&mut self) -> Option<CallFrame> {
Expand Down Expand Up @@ -422,7 +416,7 @@ impl Context {
break;
}

fp = frame.fp as usize;
fp = frame.restore_fp() as usize;
env_fp = frame.env_fp as usize;
self.vm.pop_frame();
}
Expand All @@ -449,7 +443,8 @@ impl Context {
match result {
CompletionType::Normal => {}
CompletionType::Return => {
self.vm.stack.truncate(self.vm.frame().fp as usize);
let restore_fp = self.vm.frame().restore_fp() as usize;
self.vm.stack.truncate(restore_fp);

let result = self.vm.take_return_value();
if self.vm.frame().exit_early() {
Expand All @@ -460,7 +455,7 @@ impl Context {
self.vm.pop_frame();
}
CompletionType::Throw => {
let mut fp = self.vm.frame().fp;
let mut fp = self.vm.frame().restore_fp();
let mut env_fp = self.vm.frame().env_fp;
if self.vm.frame().exit_early() {
self.vm.environments.truncate(env_fp as usize);
Expand All @@ -476,8 +471,8 @@ impl Context {
self.vm.pop_frame();

while let Some(frame) = self.vm.frames.last_mut() {
fp = frame.fp;
env_fp = frame.fp;
fp = frame.restore_fp();
env_fp = frame.env_fp;
let pc = frame.pc;
let exit_early = frame.exit_early();

Expand Down
8 changes: 3 additions & 5 deletions core/engine/src/vm/opcode/arguments.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
use crate::{
builtins::function::arguments::{MappedArguments, UnmappedArguments},
vm::{CallFrame, CompletionType},
vm::CompletionType,
Context, JsResult,
};

Expand All @@ -19,15 +19,14 @@ impl Operation for CreateMappedArgumentsObject {
const COST: u8 = 8;

fn execute(context: &mut Context) -> JsResult<CompletionType> {
let arguments_start = context.vm.frame().fp as usize + CallFrame::FIRST_ARGUMENT_POSITION;
let function_object = context
.vm
.frame()
.function(&context.vm)
.clone()
.expect("there should be a function object");
let code = context.vm.frame().code_block().clone();
let args = context.vm.stack[arguments_start..].to_vec();
let args = context.vm.frame().arguments(&context.vm).to_vec();

let env = context.vm.environments.current();
let arguments = MappedArguments::new(
Expand Down Expand Up @@ -55,8 +54,7 @@ impl Operation for CreateUnmappedArgumentsObject {
const COST: u8 = 4;

fn execute(context: &mut Context) -> JsResult<CompletionType> {
let arguments_start = context.vm.frame().fp as usize + CallFrame::FIRST_ARGUMENT_POSITION;
let args = context.vm.stack[arguments_start..].to_vec();
let args = context.vm.frame().arguments(&context.vm).to_vec();
let arguments = UnmappedArguments::new(&args, context);
context.vm.push(arguments);
Ok(CompletionType::Normal)
Expand Down
38 changes: 6 additions & 32 deletions core/engine/src/vm/opcode/generator/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ use crate::{
vm::{
call_frame::GeneratorResumeKind,
opcode::{Operation, ReThrow},
CallFrame, CompletionType,
CompletionType,
},
Context, JsError, JsObject, JsResult, JsValue,
};
Expand All @@ -37,36 +37,12 @@ impl Operation for Generator {
fn execute(context: &mut Context) -> JsResult<CompletionType> {
let r#async = context.vm.read::<u8>() != 0;

let frame = context.vm.frame();
let code_block = frame.code_block().clone();
let active_runnable = frame.active_runnable.clone();
let active_function = frame.function(&context.vm);
let environments = frame.environments.clone();
let realm = frame.realm.clone();
let pc = frame.pc;

let mut dummy_call_frame = CallFrame::new(code_block, active_runnable, environments, realm);
dummy_call_frame.pc = pc;
let mut call_frame = std::mem::replace(context.vm.frame_mut(), dummy_call_frame);

context
.vm
.frame_mut()
.set_exit_early(call_frame.exit_early());

call_frame.environments = context.vm.environments.clone();
call_frame.realm = context.realm().clone();

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 active_function = context.vm.frame().function(&context.vm);
let this_function_object =
active_function.expect("active function should be set to the generator");

let frame = GeneratorContext::from_current(context);

let proto = this_function_object
.get(PROTOTYPE, context)
.expect("generator must have a prototype property")
Expand All @@ -88,7 +64,7 @@ impl Operation for Generator {
proto,
AsyncGenerator {
state: AsyncGeneratorState::SuspendedStart,
context: Some(GeneratorContext::new(stack, call_frame)),
context: Some(frame),
queue: VecDeque::new(),
},
)
Expand All @@ -97,9 +73,7 @@ impl Operation for Generator {
context.root_shape(),
proto,
crate::builtins::generator::Generator {
state: GeneratorState::SuspendedStart {
context: GeneratorContext::new(stack, call_frame),
},
state: GeneratorState::SuspendedStart { context: frame },
},
)
};
Expand Down
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