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refactor(tvix/eval): Carry lambda & upvalues directly in CallFrame

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CallFrame has to work for both thunks & closures (as a thunk is
basically a "weird 0-argument closure").

We opt to store the common, relevant fields directly in the frame to
avoid having to dereference through the nested structures
constantly (which would be especially annoying in the case of thunks).

Change-Id: I47781597b84ec5cd55502dba1713e92cf2592af3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6348
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
This commit is contained in:
Vincent Ambo 2022-08-29 18:20:28 +03:00 committed by tazjin
parent 25c62dd0ef
commit ce498052e6
1 changed files with 25 additions and 13 deletions
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38
tvix/eval/src/vm.rs
View file

@ -1,12 +1,12 @@
//! This module implements the virtual (or abstract) machine that runs //! This module implements the virtual (or abstract) machine that runs
//! Tvix bytecode. //! Tvix bytecode.
use std::{cell::Ref, rc::Rc}; use std::rc::Rc;
use crate::{ use crate::{
chunk::Chunk, chunk::Chunk,
errors::{Error, ErrorKind, EvalResult}, errors::{Error, ErrorKind, EvalResult},
opcode::{ConstantIdx, Count, JumpOffset, OpCode, StackIdx}, opcode::{ConstantIdx, Count, JumpOffset, OpCode, StackIdx, UpvalueIdx},
upvalues::UpvalueCarrier, upvalues::UpvalueCarrier,
value::{Closure, Lambda, NixAttrs, NixList, Value}, value::{Closure, Lambda, NixAttrs, NixList, Value},
}; };
@ -15,11 +15,19 @@ use crate::{
use crate::disassembler::Tracer; use crate::disassembler::Tracer;
struct CallFrame { struct CallFrame {
closure: Closure, lambda: Rc<Lambda>,
upvalues: Vec<Value>,
ip: usize, ip: usize,
stack_offset: usize, stack_offset: usize,
} }
impl CallFrame {
/// Retrieve an upvalue from this frame at the given index.
fn upvalue(&self, idx: UpvalueIdx) -> &Value {
&self.upvalues[idx.0]
}
}
pub struct VM { pub struct VM {
frames: Vec<CallFrame>, frames: Vec<CallFrame>,
stack: Vec<Value>, stack: Vec<Value>,
@ -86,8 +94,8 @@ impl VM {
&self.frames[self.frames.len() - 1] &self.frames[self.frames.len() - 1]
} }
fn chunk(&self) -> Ref<'_, Chunk> { fn chunk(&self) -> &Chunk {
self.frame().closure.chunk() &self.frame().lambda.chunk
} }
fn frame_mut(&mut self) -> &mut CallFrame { fn frame_mut(&mut self) -> &mut CallFrame {
@ -117,9 +125,10 @@ impl VM {
&self.stack[self.stack.len() - 1 - offset] &self.stack[self.stack.len() - 1 - offset]
} }
fn call(&mut self, closure: Closure, arg_count: usize) { pub fn call(&mut self, lambda: Rc<Lambda>, upvalues: Vec<Value>, arg_count: usize) {
let frame = CallFrame { let frame = CallFrame {
closure, lambda,
upvalues,
ip: 0, ip: 0,
stack_offset: self.stack.len() - arg_count, stack_offset: self.stack.len() - arg_count,
}; };
@ -353,7 +362,7 @@ impl VM {
kind: ErrorKind::UnknownDynamicVariable(_), kind: ErrorKind::UnknownDynamicVariable(_),
.. ..
}) => { }) => {
let value = self.frame().closure.upvalue(idx).clone(); let value = self.frame().upvalue(idx).clone();
self.push(value); self.push(value);
} }
@ -370,7 +379,10 @@ impl VM {
OpCode::OpCall => { OpCode::OpCall => {
let callable = self.pop(); let callable = self.pop();
match callable { match callable {
Value::Closure(closure) => self.call(closure, 1), Value::Closure(closure) => {
self.call(closure.lambda(), closure.upvalues().to_vec(), 1)
}
Value::Builtin(builtin) => { Value::Builtin(builtin) => {
let arg = self.pop(); let arg = self.pop();
let result = builtin.apply(arg)?; let result = builtin.apply(arg)?;
@ -381,7 +393,7 @@ impl VM {
} }
OpCode::OpGetUpvalue(upv_idx) => { OpCode::OpGetUpvalue(upv_idx) => {
let value = self.frame().closure.upvalue(upv_idx).clone(); let value = self.frame().upvalue(upv_idx).clone();
if let Value::DynamicUpvalueMissing(name) = value { if let Value::DynamicUpvalueMissing(name) = value {
return Err( return Err(
ErrorKind::UnknownDynamicVariable(name.as_str().to_string()).into() ErrorKind::UnknownDynamicVariable(name.as_str().to_string()).into()
@ -419,7 +431,7 @@ impl VM {
} }
OpCode::DataUpvalueIdx(upv_idx) => { OpCode::DataUpvalueIdx(upv_idx) => {
closure.push_upvalue(self.frame().closure.upvalue(upv_idx).clone()); closure.push_upvalue(self.frame().upvalue(upv_idx).clone());
} }
OpCode::DataDynamicIdx(ident_idx) => { OpCode::DataDynamicIdx(ident_idx) => {
@ -532,7 +544,7 @@ impl VM {
kind: ErrorKind::UnknownDynamicVariable(_), kind: ErrorKind::UnknownDynamicVariable(_),
.. ..
}) => match up { }) => match up {
Some(idx) => Ok(self.frame().closure.upvalue(idx).clone()), Some(idx) => Ok(self.frame().upvalue(idx).clone()),
None => Ok(Value::DynamicUpvalueMissing(ident.into())), None => Ok(Value::DynamicUpvalueMissing(ident.into())),
}, },
@ -567,6 +579,6 @@ pub fn run_lambda(lambda: Lambda) -> EvalResult<Value> {
with_stack: vec![], with_stack: vec![],
}; };
vm.call(Closure::new(Rc::new(lambda)), 0); vm.call(Rc::new(lambda), vec![], 0);
vm.run() vm.run()
} }