diff options
Diffstat (limited to 'tvix/eval/src/vm.rs')
| -rw-r--r-- | tvix/eval/src/vm.rs | 131 |
1 files changed, 83 insertions, 48 deletions
diff --git a/tvix/eval/src/vm.rs b/tvix/eval/src/vm.rs index a2b370ab9288..5fabdb491e1f 100644 --- a/tvix/eval/src/vm.rs +++ b/tvix/eval/src/vm.rs @@ -6,7 +6,7 @@ use std::{cell::RefMut, rc::Rc}; use crate::{ chunk::Chunk, errors::{Error, ErrorKind, EvalResult}, - opcode::{ConstantIdx, Count, JumpOffset, OpCode, StackIdx, UpvalueIdx}, + opcode::{CodeIdx, ConstantIdx, Count, JumpOffset, OpCode, StackIdx, UpvalueIdx}, upvalues::UpvalueCarrier, value::{Closure, Lambda, NixAttrs, NixList, Thunk, Value}, }; @@ -37,30 +37,50 @@ pub struct VM { with_stack: Vec<usize>, } +/// This macro wraps a computation that returns an ErrorKind or a +/// result, and wraps the ErrorKind in an Error struct if present. +/// +/// The reason for this macro's existence is that calculating spans is +/// potentially expensive, so it should be avoided to the last moment +/// (i.e. definite instantiation of a runtime error) if possible. +macro_rules! fallible { + ( $self:ident, $body:expr) => { + match $body { + Ok(result) => result, + Err(kind) => { + return Err(Error { + kind, + span: $self.current_span(), + }) + } + } + }; +} + #[macro_export] macro_rules! arithmetic_op { ( $self:ident, $op:tt ) => {{ let b = $self.pop(); let a = $self.pop(); - let result = arithmetic_op!(a, b, $op); + let result = fallible!($self, arithmetic_op!(a, b, $op)); $self.push(result); }}; ( $a:ident, $b:ident, $op:tt ) => {{ match ($a, $b) { - (Value::Integer(i1), Value::Integer(i2)) => Value::Integer(i1 $op i2), - (Value::Float(f1), Value::Float(f2)) => Value::Float(f1 $op f2), - (Value::Integer(i1), Value::Float(f2)) => Value::Float(i1 as f64 $op f2), - (Value::Float(f1), Value::Integer(i2)) => Value::Float(f1 $op i2 as f64), + (Value::Integer(i1), Value::Integer(i2)) => Ok(Value::Integer(i1 $op i2)), + (Value::Float(f1), Value::Float(f2)) => Ok(Value::Float(f1 $op f2)), + (Value::Integer(i1), Value::Float(f2)) => Ok(Value::Float(i1 as f64 $op f2)), + (Value::Float(f1), Value::Integer(i2)) => Ok(Value::Float(f1 $op i2 as f64)), - (v1, v2) => return Err(ErrorKind::TypeError { + (v1, v2) => Err(ErrorKind::TypeError { expected: "number (either int or float)", actual: if v1.is_number() { v2.type_of() } else { v1.type_of() }, - }.into()), + }), } }}; } @@ -80,10 +100,10 @@ macro_rules! cmp_op { (Value::Float(f1), Value::Integer(i2)) => f1 $op (i2 as f64), (Value::String(s1), Value::String(s2)) => s1 $op s2, - (lhs, rhs) => return Err(ErrorKind::Incomparable { + (lhs, rhs) => return Err($self.error(ErrorKind::Incomparable { lhs: lhs.type_of(), rhs: rhs.type_of(), - }.into()), + })), }; $self.push(Value::Bool(result)); @@ -126,6 +146,21 @@ impl VM { &self.stack[self.stack.len() - 1 - offset] } + /// Returns the source span of the instruction currently being + /// executed. + fn current_span(&self) -> codemap::Span { + self.chunk().get_span(CodeIdx(self.frame().ip - 1)) + } + + /// Construct an error from the given ErrorKind and the source + /// span of the current instruction. + fn error(&self, kind: ErrorKind) -> Error { + Error { + kind, + span: self.current_span(), + } + } + pub fn call(&mut self, lambda: Rc<Lambda>, upvalues: Vec<Value>, arg_count: usize) { let frame = CallFrame { lambda, @@ -171,7 +206,7 @@ impl VM { let result = if let (Value::String(s1), Value::String(s2)) = (&a, &b) { Value::String(s1.concat(s2)) } else { - arithmetic_op!(a, b, +) + fallible!(self, arithmetic_op!(a, b, +)) }; self.push(result) @@ -182,7 +217,7 @@ impl VM { OpCode::OpDiv => arithmetic_op!(self, /), OpCode::OpInvert => { - let v = self.pop().as_bool()?; + let v = fallible!(self, self.pop().as_bool()); self.push(Value::Bool(!v)); } @@ -190,11 +225,10 @@ impl VM { Value::Integer(i) => self.push(Value::Integer(-i)), Value::Float(f) => self.push(Value::Float(-f)), v => { - return Err(ErrorKind::TypeError { + return Err(self.error(ErrorKind::TypeError { expected: "number (either int or float)", actual: v.type_of(), - } - .into()) + })); } }, @@ -218,30 +252,29 @@ impl VM { OpCode::OpAttrPath(Count(count)) => self.run_attr_path(count)?, OpCode::OpAttrsUpdate => { - let rhs = unwrap_or_clone_rc(self.pop().to_attrs()?); - let lhs = unwrap_or_clone_rc(self.pop().to_attrs()?); + let rhs = unwrap_or_clone_rc(fallible!(self, self.pop().to_attrs())); + let lhs = unwrap_or_clone_rc(fallible!(self, self.pop().to_attrs())); self.push(Value::Attrs(Rc::new(lhs.update(rhs)))) } OpCode::OpAttrsSelect => { - let key = self.pop().to_string()?; - let attrs = self.pop().to_attrs()?; + let key = fallible!(self, self.pop().to_string()); + let attrs = fallible!(self, self.pop().to_attrs()); match attrs.select(key.as_str()) { Some(value) => self.push(value.clone()), None => { - return Err(ErrorKind::AttributeNotFound { + return Err(self.error(ErrorKind::AttributeNotFound { name: key.as_str().to_string(), - } - .into()) + })) } } } OpCode::OpAttrsTrySelect => { - let key = self.pop().to_string()?; + let key = fallible!(self, self.pop().to_string()); let value = match self.pop() { Value::Attrs(attrs) => match attrs.select(key.as_str()) { Some(value) => value.clone(), @@ -255,7 +288,7 @@ impl VM { } OpCode::OpAttrsIsSet => { - let key = self.pop().to_string()?; + let key = fallible!(self, self.pop().to_string()); let result = match self.pop() { Value::Attrs(attrs) => attrs.contains(key.as_str()), @@ -274,8 +307,8 @@ impl VM { } OpCode::OpConcat => { - let rhs = self.pop().to_list()?; - let lhs = self.pop().to_list()?; + let rhs = fallible!(self, self.pop().to_list()); + let lhs = fallible!(self, self.pop().to_list()); self.push(Value::List(lhs.concat(&rhs))) } @@ -286,13 +319,13 @@ impl VM { } OpCode::OpJumpIfTrue(JumpOffset(offset)) => { - if self.peek(0).as_bool()? { + if fallible!(self, self.peek(0).as_bool()) { self.frame_mut().ip += offset; } } OpCode::OpJumpIfFalse(JumpOffset(offset)) => { - if !self.peek(0).as_bool()? { + if !fallible!(self, self.peek(0).as_bool()) { self.frame_mut().ip += offset; } } @@ -311,11 +344,10 @@ impl VM { OpCode::OpAssertBool => { let val = self.peek(0); if !val.is_bool() { - return Err(ErrorKind::TypeError { + return Err(self.error(ErrorKind::TypeError { expected: "bool", actual: val.type_of(), - } - .into()); + })); } } @@ -347,13 +379,13 @@ impl VM { } OpCode::OpResolveWith => { - let ident = self.pop().to_string()?; + let ident = fallible!(self, self.pop().to_string()); let value = self.resolve_with(ident.as_str())?; self.push(value) } OpCode::OpResolveWithOrUpvalue(idx) => { - let ident = self.pop().to_string()?; + let ident = fallible!(self, self.pop().to_string()); match self.resolve_with(ident.as_str()) { // Variable found in local `with`-stack. Ok(value) => self.push(value), @@ -372,8 +404,8 @@ impl VM { } OpCode::OpAssert => { - if !self.pop().as_bool()? { - return Err(ErrorKind::AssertionFailed.into()); + if !fallible!(self, self.pop().as_bool()) { + return Err(self.error(ErrorKind::AssertionFailed)); } } @@ -386,19 +418,18 @@ impl VM { Value::Builtin(builtin) => { let arg = self.pop(); - let result = builtin.apply(arg)?; + let result = fallible!(self, builtin.apply(arg)); self.push(result); } - _ => return Err(ErrorKind::NotCallable.into()), + _ => return Err(self.error(ErrorKind::NotCallable)), }; } OpCode::OpGetUpvalue(upv_idx) => { let value = self.frame().upvalue(upv_idx).clone(); if let Value::DynamicUpvalueMissing(name) = value { - return Err( - ErrorKind::UnknownDynamicVariable(name.as_str().to_string()).into() - ); + return Err(self + .error(ErrorKind::UnknownDynamicVariable(name.as_str().to_string()))); } self.push(value); @@ -446,7 +477,7 @@ impl VM { let mut value = self.pop(); if let Value::Thunk(thunk) = value { - thunk.force(self)?; + fallible!(self, thunk.force(self)); value = thunk.value().clone(); } @@ -498,7 +529,7 @@ impl VM { let mut path = Vec::with_capacity(count); for _ in 0..count { - path.push(self.pop().to_string()?); + path.push(fallible!(self, self.pop().to_string())); } self.push(Value::AttrPath(path)); @@ -506,7 +537,11 @@ impl VM { } fn run_attrset(&mut self, count: usize) -> EvalResult<()> { - let attrs = NixAttrs::construct(count, self.stack.split_off(self.stack.len() - count * 2))?; + let attrs = fallible!( + self, + NixAttrs::construct(count, self.stack.split_off(self.stack.len() - count * 2)) + ); + self.push(Value::Attrs(Rc::new(attrs))); Ok(()) } @@ -518,7 +553,7 @@ impl VM { let mut out = String::new(); for _ in 0..count { - out.push_str(self.pop().to_string()?.as_str()); + out.push_str(fallible!(self, self.pop().to_string()).as_str()); } self.push(Value::String(out.into())); @@ -527,7 +562,7 @@ impl VM { fn resolve_dynamic_upvalue(&mut self, ident_idx: ConstantIdx) -> EvalResult<Value> { let chunk = self.chunk(); - let ident = chunk.constant(ident_idx).as_str()?.to_string(); + let ident = fallible!(self, chunk.constant(ident_idx).as_str()).to_string(); // Peek at the current instruction (note: IP has already // advanced!) to see if it is actually data indicating a @@ -560,14 +595,14 @@ impl VM { /// Resolve a dynamic identifier through the with-stack at runtime. fn resolve_with(&self, ident: &str) -> EvalResult<Value> { for idx in self.with_stack.iter().rev() { - let with = self.stack[*idx].as_attrs()?; + let with = fallible!(self, self.stack[*idx].as_attrs()); match with.select(ident) { None => continue, Some(val) => return Ok(val.clone()), } } - Err(ErrorKind::UnknownDynamicVariable(ident.to_string()).into()) + Err(self.error(ErrorKind::UnknownDynamicVariable(ident.to_string()))) } /// Populate the upvalue fields of a thunk or closure under construction. @@ -619,7 +654,7 @@ impl VM { Value::List(list) => list.iter().try_for_each(|elem| self.force_for_output(elem)), Value::Thunk(thunk) => { - thunk.force(self)?; + fallible!(self, thunk.force(self)); self.force_for_output(&thunk.value()) } |