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refactor(tvix/eval): encapsulate internal mutability within Closure

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This is required to efficiently construct the upvalue array at
runtime, as there are situations where during Closure construction
multiple things already have a reference to the closure (e.g. a
self-reference).

Change-Id: I35263b845fdc695dc873de489f5168d39b370f6a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6312
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
This commit is contained in:
Vincent Ambo 2022-08-27 20:41:10 +03:00 • committed by tazjin
parent e646d5170c
commit 3089e46eb1
3 changed files with 47 additions and 25 deletions
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32
tvix/eval/src/vm.rs
View file

@ -1,12 +1,12 @@
//! This module implements the virtual (or abstract) machine that runs
//! Tvix bytecode.
use std::rc::Rc;
use std::{cell::Ref, rc::Rc};
use crate::{
chunk::Chunk,
errors::{ErrorKind, EvalResult},
opcode::{Count, JumpOffset, OpCode, StackIdx, UpvalueIdx},
opcode::{Count, JumpOffset, OpCode, StackIdx},
value::{Closure, Lambda, NixAttrs, NixList, Value},
};
@ -85,8 +85,8 @@ impl VM {
&self.frames[self.frames.len() - 1]
}
fn chunk(&self) -> &Chunk {
&self.frame().closure.lambda.chunk
fn chunk(&self) -> Ref<'_, Chunk> {
self.frame().closure.chunk()
}
fn frame_mut(&mut self) -> &mut CallFrame {
@ -353,35 +353,35 @@ impl VM {
};
}
OpCode::OpGetUpvalue(UpvalueIdx(upv_idx)) => {
let value = self.frame().closure.upvalues[upv_idx].clone();
OpCode::OpGetUpvalue(upv_idx) => {
let value = self.frame().closure.upvalue(upv_idx).clone();
self.push(value);
}
OpCode::OpClosure(idx) => {
let mut closure = self.chunk().constant(idx).clone().to_closure()?;
let closure = self.chunk().constant(idx).clone().to_closure()?;
debug_assert!(
closure.lambda.upvalue_count > 0,
closure.upvalue_count() > 0,
"OpClosure should not be called for plain lambdas"
);
for _ in 0..closure.lambda.upvalue_count {
for _ in 0..closure.upvalue_count() {
match self.inc_ip() {
OpCode::DataLocalIdx(StackIdx(local_idx)) => {
let idx = self.frame().stack_offset + local_idx;
closure.upvalues.push(self.stack[idx].clone());
closure.push_upvalue(self.stack[idx].clone());
}
OpCode::DataUpvalueIdx(UpvalueIdx(upv_idx)) => {
closure
.upvalues
.push(self.frame().closure.upvalues[upv_idx].clone());
OpCode::DataUpvalueIdx(upv_idx) => {
closure.push_upvalue(self.frame().closure.upvalue(upv_idx).clone());
}
OpCode::DataDynamicIdx(ident_idx) => {
let ident = self.chunk().constant(ident_idx).as_str()?;
closure.upvalues.push(self.resolve_with(ident)?);
let chunk = self.chunk();
let ident = chunk.constant(ident_idx).as_str()?.to_string();
drop(chunk); // some lifetime trickery due to cell::Ref
closure.push_upvalue(self.resolve_with(&ident)?);
}
_ => panic!("compiler error: missing closure operand"),