Optimize; Revert to branch-style comparisons for performance

dust-cli/src/main.rs

@@ -199,24 +199,15 @@ fn main() {
     let chunk = compiler.finish(None, None);
     let compile_end = start_time.elapsed();
 
-    let mut vm = Vm::new(&source, &chunk, None);
+    let vm = Vm::new(&source, &chunk, None);
+    let return_value = vm.run();
+    let run_end = start_time.elapsed();
 
-    match vm.run() {
+    if let Some(value) = return_value {
-        Ok(Some(value)) => {
         if !mode.no_output {
             println!("{}", value)
         }
     }
-        Ok(None) => {}
-        Err(error) => {
-            let dust_error = DustError::runtime(error, &source);
-            let report = dust_error.report();
-
-            eprintln!("{report}");
-        }
-    }
-
-    let run_end = start_time.elapsed();
 
     if mode.time {
         let compile_time = compile_end.as_micros();

dust-lang/src/compiler/mod.rs

@@ -856,12 +856,12 @@ impl<'src> Compiler<'src> {
 
         let destination = self.next_register();
         let comparison = match operator {
-            Token::DoubleEqual => Instruction::equal(destination, true, left, right),
+            Token::DoubleEqual => Instruction::equal(true, left, right),
-            Token::BangEqual => Instruction::equal(destination, false, left, right),
+            Token::BangEqual => Instruction::equal(false, left, right),
-            Token::Less => Instruction::less(destination, true, left, right),
+            Token::Less => Instruction::less(true, left, right),
-            Token::LessEqual => Instruction::less_equal(destination, true, left, right),
+            Token::LessEqual => Instruction::less_equal(true, left, right),
-            Token::Greater => Instruction::less_equal(destination, false, left, right),
+            Token::Greater => Instruction::less_equal(false, left, right),
-            Token::GreaterEqual => Instruction::less(destination, false, left, right),
+            Token::GreaterEqual => Instruction::less(false, left, right),
             _ => {
                 return Err(CompileError::ExpectedTokenMultiple {
                     expected: &[
@@ -877,8 +877,14 @@ impl<'src> Compiler<'src> {
                 })
             }
         };
+        let jump = Instruction::jump(1, true);
+        let load_false = Instruction::load_boolean(destination, false, true);
+        let load_true = Instruction::load_boolean(destination, true, false);
 
         self.emit_instruction(comparison, Type::Boolean, operator_position);
+        self.emit_instruction(jump, Type::None, operator_position);
+        self.emit_instruction(load_false, Type::Boolean, operator_position);
+        self.emit_instruction(load_true, Type::Boolean, operator_position);
 
         Ok(())
     }
@@ -1132,7 +1138,19 @@ impl<'src> Compiler<'src> {
         self.advance()?;
         self.parse_expression()?;
 
-        if let Some((instruction, _, _)) = self.instructions.last() {
+        if matches!(
+            self.get_last_operations(),
+            Some([
+                Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL,
+                Operation::JUMP,
+                Operation::LOAD_BOOLEAN,
+                Operation::LOAD_BOOLEAN
+            ]),
+        ) {
+            self.instructions.pop();
+            self.instructions.pop();
+            self.instructions.pop();
+        } else if let Some((instruction, _, _)) = self.instructions.last() {
             let argument = match instruction.as_argument() {
                 Some(argument) => argument,
                 None => {
@@ -1264,6 +1282,19 @@ impl<'src> Compiler<'src> {
 
         self.parse_expression()?;
 
+        if matches!(
+            self.get_last_operations(),
+            Some([
+                Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL,
+                Operation::JUMP,
+                Operation::LOAD_BOOLEAN,
+                Operation::LOAD_BOOLEAN
+            ]),
+        ) {
+            self.instructions.pop();
+            self.instructions.pop();
+            self.instructions.pop();
+        } else {
             let (expression_instruction, expression_type, expression_position) =
                 self.instructions.last().unwrap();
 
@@ -1287,19 +1318,6 @@ impl<'src> Compiler<'src> {
             let test = Instruction::test(test_argument, true);
 
             self.emit_instruction(test, Type::None, self.current_position);
-
-        if matches!(
-            self.get_last_operations(),
-            Some([
-                Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL,
-                Operation::JUMP,
-                Operation::LOAD_BOOLEAN,
-                Operation::LOAD_BOOLEAN,
-            ],)
-        ) {
-            self.instructions.pop();
-            self.instructions.pop();
-            self.instructions.pop();
         }
 
         let block_start = self.instructions.len();

dust-lang/src/instruction/equal.rs

@@ -1,7 +1,6 @@
 use crate::{Argument, Instruction, Operation};
 
 pub struct Equal {
-    pub destination: u8,
     pub value: bool,
     pub left: Argument,
     pub right: Argument,
@@ -9,27 +8,20 @@ pub struct Equal {
 
 impl From<&Instruction> for Equal {
     fn from(instruction: &Instruction) -> Self {
-        let destination = instruction.a_field();
         let value = instruction.d_field();
         let (left, right) = instruction.b_and_c_as_arguments();
 
-        Equal {
+        Equal { value, left, right }
-            destination,
-            value,
-            left,
-            right,
-        }
     }
 }
 
 impl From<Equal> for Instruction {
     fn from(equal: Equal) -> Self {
         let operation = Operation::EQUAL;
-        let a = equal.destination;
         let (b, b_is_constant) = equal.left.as_index_and_constant_flag();
         let (c, c_is_constant) = equal.right.as_index_and_constant_flag();
         let d = equal.value;
 
-        Instruction::new(operation, a, b, c, b_is_constant, c_is_constant, d)
+        Instruction::new(operation, 0, b, c, b_is_constant, c_is_constant, d)
     }
 }

dust-lang/src/instruction/less.rs

@@ -1,7 +1,6 @@
 use crate::{Argument, Instruction, Operation};
 
 pub struct Less {
-    pub destination: u8,
     pub value: bool,
     pub left: Argument,
     pub right: Argument,
@@ -9,27 +8,20 @@ pub struct Less {
 
 impl From<&Instruction> for Less {
     fn from(instruction: &Instruction) -> Self {
-        let destination = instruction.a_field();
         let value = instruction.d_field();
         let (left, right) = instruction.b_and_c_as_arguments();
 
-        Less {
+        Less { value, left, right }
-            destination,
-            value,
-            left,
-            right,
-        }
     }
 }
 
 impl From<Less> for Instruction {
     fn from(less: Less) -> Self {
         let operation = Operation::LESS;
-        let a = less.destination;
         let (b, b_is_constant) = less.left.as_index_and_constant_flag();
         let (c, c_is_constant) = less.right.as_index_and_constant_flag();
         let d = less.value;
 
-        Instruction::new(operation, a, b, c, b_is_constant, c_is_constant, d)
+        Instruction::new(operation, 0, b, c, b_is_constant, c_is_constant, d)
     }
 }

dust-lang/src/instruction/less_equal.rs

@@ -1,7 +1,6 @@
 use crate::{Argument, Instruction, Operation};
 
 pub struct LessEqual {
-    pub destination: u8,
     pub value: bool,
     pub left: Argument,
     pub right: Argument,
@@ -9,27 +8,20 @@ pub struct LessEqual {
 
 impl From<&Instruction> for LessEqual {
     fn from(instruction: &Instruction) -> Self {
-        let destination = instruction.a_field();
         let value = instruction.d_field();
         let (left, right) = instruction.b_and_c_as_arguments();
 
-        LessEqual {
+        LessEqual { value, left, right }
-            destination,
-            value,
-            left,
-            right,
-        }
     }
 }
 
 impl From<LessEqual> for Instruction {
     fn from(less_equal: LessEqual) -> Self {
         let operation = Operation::LESS_EQUAL;
-        let a = less_equal.destination;
         let (b, b_options) = less_equal.left.as_index_and_constant_flag();
         let (c, c_options) = less_equal.right.as_index_and_constant_flag();
         let d = less_equal.value;
 
-        Instruction::new(operation, a, b, c, b_options, c_options, d)
+        Instruction::new(operation, 0, b, c, b_options, c_options, d)
     }
 }

dust-lang/src/instruction/mod.rs

@@ -152,7 +152,7 @@ use crate::NativeFunction;
 #[derive(Clone, Copy, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct Instruction(u32);
 
-#[derive(Clone, Copy, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct InstructionData {
     pub a: u8,
     pub b: u8,
@@ -343,36 +343,16 @@ impl Instruction {
         })
     }
 
-    pub fn equal(destination: u8, value: bool, left: Argument, right: Argument) -> Instruction {
+    pub fn equal(value: bool, left: Argument, right: Argument) -> Instruction {
-        Instruction::from(Equal {
+        Instruction::from(Equal { value, left, right })
-            destination,
-            value,
-            left,
-            right,
-        })
     }
 
-    pub fn less(destination: u8, value: bool, left: Argument, right: Argument) -> Instruction {
+    pub fn less(value: bool, left: Argument, right: Argument) -> Instruction {
-        Instruction::from(Less {
+        Instruction::from(Less { value, left, right })
-            destination,
-            value,
-            left,
-            right,
-        })
     }
 
-    pub fn less_equal(
+    pub fn less_equal(value: bool, left: Argument, right: Argument) -> Instruction {
-        destination: u8,
+        Instruction::from(LessEqual { value, left, right })
-        value: bool,
-        left: Argument,
-        right: Argument,
-    ) -> Instruction {
-        Instruction::from(LessEqual {
-            destination,
-            value,
-            left,
-            right,
-        })
     }
 
     pub fn negate(destination: u8, argument: Argument) -> Instruction {
@@ -661,37 +641,22 @@ impl Instruction {
                 format!("if {bang}{argument} {{ JUMP +1 }} else {{ R{destination} = {argument} }}")
             }
             Operation::EQUAL => {
-                let Equal {
+                let Equal { value, left, right } = Equal::from(self);
-                    destination,
-                    value,
-                    left,
-                    right,
-                } = Equal::from(self);
                 let comparison_symbol = if value { "==" } else { "!=" };
 
-                format!("R{destination} = {left} {comparison_symbol} {right}")
+                format!("if {left} {comparison_symbol} {right} {{ JUMP +1 }}")
             }
             Operation::LESS => {
-                let Less {
+                let Less { value, left, right } = Less::from(self);
-                    destination,
-                    value,
-                    left,
-                    right,
-                } = Less::from(self);
                 let comparison_symbol = if value { "<" } else { ">=" };
 
-                format!("R{destination} = {left} {comparison_symbol} {right}")
+                format!("if {left} {comparison_symbol} {right} {{ JUMP +1 }}")
             }
             Operation::LESS_EQUAL => {
-                let LessEqual {
+                let LessEqual { value, left, right } = LessEqual::from(self);
-                    destination,
-                    value,
-                    left,
-                    right,
-                } = LessEqual::from(self);
                 let comparison_symbol = if value { "<=" } else { ">" };
 
-                format!("R{destination} = {left} {comparison_symbol} {right}")
+                format!("if {left} {comparison_symbol} {right} {{ JUMP +1 }}")
             }
             Operation::NEGATE => {
                 let Negate {

dust-lang/src/value/abstract_value.rs

@@ -17,23 +17,23 @@ impl AbstractValue {
         ValueRef::Abstract(self)
     }
 
-    pub fn to_concrete_owned(&self, vm: &Vm) -> Result<ConcreteValue, VmError> {
+    pub fn to_concrete_owned(&self, vm: &Vm) -> ConcreteValue {
         match self {
-            AbstractValue::FunctionSelf => Ok(ConcreteValue::function(vm.chunk().clone())),
+            AbstractValue::FunctionSelf => ConcreteValue::function(vm.chunk().clone()),
             AbstractValue::List { item_pointers, .. } => {
                 let mut items: Vec<ConcreteValue> = Vec::with_capacity(item_pointers.len());
 
                 for pointer in item_pointers {
-                    let item_option = vm.follow_pointer_allow_empty(*pointer)?;
+                    let item_option = vm.follow_pointer_allow_empty(*pointer);
                     let item = match item_option {
-                        Some(value_ref) => value_ref.into_concrete_owned(vm)?,
+                        Some(value_ref) => value_ref.into_concrete_owned(vm),
                         None => continue,
                     };
 
                     items.push(item);
                 }
 
-                Ok(ConcreteValue::List(items))
+                ConcreteValue::List(items)
             }
         }
     }
@@ -54,7 +54,7 @@ impl AbstractValue {
                         display.push_str(", ");
                     }
 
-                    let item_display = vm.follow_pointer(*item)?.display(vm)?;
+                    let item_display = vm.follow_pointer(*item).display(vm)?;
 
                     display.push_str(&item_display);
                 }

dust-lang/src/value/mod.rs

@@ -25,10 +25,10 @@ impl Value {
         }
     }
 
-    pub fn into_concrete_owned(self, vm: &Vm) -> Result<ConcreteValue, VmError> {
+    pub fn into_concrete_owned(self, vm: &Vm) -> ConcreteValue {
         match self {
             Value::Abstract(abstract_value) => abstract_value.to_concrete_owned(vm),
-            Value::Concrete(concrete_value) => Ok(concrete_value),
+            Value::Concrete(concrete_value) => concrete_value,
         }
     }
 
@@ -64,10 +64,10 @@ impl ValueRef<'_> {
         }
     }
 
-    pub fn into_concrete_owned(self, vm: &Vm) -> Result<ConcreteValue, VmError> {
+    pub fn into_concrete_owned(self, vm: &Vm) -> ConcreteValue {
         match self {
             ValueRef::Abstract(abstract_value) => abstract_value.to_concrete_owned(vm),
-            ValueRef::Concrete(concrete_value) => Ok(concrete_value.clone()),
+            ValueRef::Concrete(concrete_value) => concrete_value.clone(),
         }
     }
 

dust-lang/src/vm/mod.rs

@@ -0,0 +1,462 @@
+//! Virtual machine and errors
+mod runners;
+
+use std::{
+    fmt::{self, Display, Formatter},
+    io,
+};
+
+use runners::{Runner, RUNNERS};
+use smallvec::SmallVec;
+
+use crate::{
+    compile, instruction::*, AbstractValue, AnnotatedError, Chunk, ConcreteValue, DustError,
+    NativeFunctionError, Span, Value, ValueError, ValueRef,
+};
+
+pub fn run(source: &str) -> Result<Option<ConcreteValue>, DustError> {
+    let chunk = compile(source)?;
+    let vm = Vm::new(source, &chunk, None);
+
+    Ok(vm.run())
+}
+
+/// Dust virtual machine.
+///
+/// See the [module-level documentation](index.html) for more information.
+#[derive(Debug)]
+pub struct Vm<'a> {
+    stack: Vec<Register>,
+
+    chunk: &'a Chunk,
+    parent: Option<&'a Vm<'a>>,
+
+    ip: usize,
+    last_assigned_register: Option<u8>,
+    source: &'a str,
+    return_value: Option<ConcreteValue>,
+}
+
+impl<'a> Vm<'a> {
+    pub fn new(source: &'a str, chunk: &'a Chunk, parent: Option<&'a Vm<'a>>) -> Self {
+        let stack = vec![Register::Empty; chunk.stack_size()];
+
+        Self {
+            chunk,
+            stack,
+            parent,
+            ip: 0,
+            last_assigned_register: None,
+            source,
+            return_value: None,
+        }
+    }
+
+    pub fn chunk(&self) -> &Chunk {
+        self.chunk
+    }
+
+    pub fn source(&self) -> &'a str {
+        self.source
+    }
+
+    pub fn current_position(&self) -> Span {
+        let index = self.ip.saturating_sub(1);
+        let (_, position) = self.chunk.instructions()[index];
+
+        position
+    }
+
+    pub fn run(mut self) -> Option<ConcreteValue> {
+        let runners = self
+            .chunk
+            .instructions()
+            .iter()
+            .map(|(instruction, _)| {
+                let (operation, data) = instruction.decode();
+                let runner = RUNNERS[operation.0 as usize];
+
+                (runner, data)
+            })
+            .collect::<Vec<(Runner, InstructionData)>>();
+
+        while self.ip < runners.len() && self.return_value.is_none() {
+            let (runner, data) = runners[self.ip];
+
+            self.ip += 1;
+
+            runner(&mut self, data);
+        }
+
+        self.return_value.take()
+    }
+
+    pub(crate) fn follow_pointer(&self, pointer: Pointer) -> ValueRef {
+        log::trace!("Follow pointer {pointer}");
+
+        match pointer {
+            Pointer::Stack(register_index) => self.open_register(register_index),
+            Pointer::Constant(constant_index) => {
+                let constant = self.get_constant(constant_index);
+
+                ValueRef::Concrete(constant)
+            }
+            Pointer::ParentStack(register_index) => {
+                assert!(self.parent.is_some(), "Vm Error: Expected parent");
+
+                self.parent.unwrap().open_register(register_index)
+            }
+            Pointer::ParentConstant(constant_index) => {
+                assert!(self.parent.is_some(), "Vm Error: Expected parent");
+
+                self.parent
+                    .unwrap()
+                    .get_constant(constant_index)
+                    .to_value_ref()
+            }
+        }
+    }
+
+    pub(crate) fn follow_pointer_allow_empty(&self, pointer: Pointer) -> Option<ValueRef> {
+        log::trace!("Follow pointer {pointer}");
+
+        match pointer {
+            Pointer::Stack(register_index) => self.open_register_allow_empty(register_index),
+            Pointer::Constant(constant_index) => {
+                let constant = self.get_constant(constant_index);
+
+                Some(ValueRef::Concrete(constant))
+            }
+            Pointer::ParentStack(register_index) => {
+                assert!(self.parent.is_some(), "Vm Error: Expected parent");
+
+                self.parent
+                    .unwrap()
+                    .open_register_allow_empty(register_index)
+            }
+            Pointer::ParentConstant(constant_index) => {
+                assert!(self.parent.is_some(), "Vm Error: Expected parent");
+
+                let constant = self
+                    .parent
+                    .unwrap()
+                    .get_constant(constant_index)
+                    .to_value_ref();
+
+                Some(constant)
+            }
+        }
+    }
+
+    fn open_register(&self, register_index: u8) -> ValueRef {
+        log::trace!("Open register R{register_index}");
+
+        let register_index = register_index as usize;
+
+        assert!(
+            register_index < self.stack.len(),
+            "VM Error: Register index out of bounds"
+        );
+
+        let register = &self.stack[register_index];
+
+        match register {
+            Register::Value(value) => value.to_ref(),
+            Register::Pointer(pointer) => self.follow_pointer(*pointer),
+            Register::Empty => panic!("VM Error: Register {register_index} is empty"),
+        }
+    }
+
+    fn open_register_allow_empty(&self, register_index: u8) -> Option<ValueRef> {
+        log::trace!("Open register R{register_index}");
+
+        let register_index = register_index as usize;
+
+        assert!(
+            register_index < self.stack.len(),
+            "VM Error: Register index out of bounds"
+        );
+
+        let register = &self.stack[register_index];
+
+        log::trace!("Open R{register_index} to {register}");
+
+        match register {
+            Register::Value(value) => Some(value.to_ref()),
+            Register::Pointer(pointer) => Some(self.follow_pointer(*pointer)),
+            Register::Empty => None,
+        }
+    }
+
+    /// DRY helper for handling JUMP instructions
+    fn jump_instructions(&mut self, offset: usize, is_positive: bool) {
+        log::trace!(
+            "Jumping {}",
+            if is_positive {
+                format!("+{}", offset)
+            } else {
+                format!("-{}", offset)
+            }
+        );
+
+        if is_positive {
+            self.ip += offset
+        } else {
+            self.ip -= offset + 1
+        }
+    }
+
+    /// DRY helper to get a value from an Argument
+    fn get_argument(&self, index: u8, is_constant: bool) -> ValueRef {
+        if is_constant {
+            self.get_constant(index).to_value_ref()
+        } else {
+            self.open_register(index)
+        }
+    }
+
+    fn set_register(&mut self, to_register: u8, register: Register) {
+        self.last_assigned_register = Some(to_register);
+        let to_register = to_register as usize;
+        let stack = self.stack.as_mut_slice();
+
+        assert!(
+            to_register < stack.len(),
+            "VM Error: Register index out of bounds"
+        );
+
+        stack[to_register] = register;
+    }
+
+    fn get_constant(&self, constant_index: u8) -> &ConcreteValue {
+        let constant_index = constant_index as usize;
+        let constants = self.chunk.constants().as_slice();
+
+        assert!(
+            constant_index < constants.len(),
+            "VM Error: Constant index out of bounds"
+        );
+
+        &constants[constant_index]
+    }
+
+    fn get_local_register(&self, local_index: u8) -> u8 {
+        let local_index = local_index as usize;
+        let locals = self.chunk.locals().as_slice();
+
+        assert!(
+            local_index < locals.len(),
+            "VM Error: Local index out of bounds"
+        );
+
+        locals[local_index].register_index
+    }
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum Register {
+    Empty,
+    Value(Value),
+    Pointer(Pointer),
+}
+
+impl Display for Register {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self {
+            Self::Empty => write!(f, "empty"),
+            Self::Value(value) => write!(f, "{}", value),
+            Self::Pointer(pointer) => write!(f, "{}", pointer),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub enum Pointer {
+    Stack(u8),
+    Constant(u8),
+    ParentStack(u8),
+    ParentConstant(u8),
+}
+
+impl Display for Pointer {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self {
+            Self::Stack(index) => write!(f, "R{}", index),
+            Self::Constant(index) => write!(f, "C{}", index),
+            Self::ParentStack(index) => write!(f, "PR{}", index),
+            Self::ParentConstant(index) => write!(f, "PC{}", index),
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum VmError {
+    // Stack errors
+    StackOverflow {
+        position: Span,
+    },
+    StackUnderflow {
+        position: Span,
+    },
+
+    // Register errors
+    EmptyRegister {
+        index: usize,
+        position: Span,
+    },
+    ExpectedConcreteValue {
+        found: AbstractValue,
+        position: Span,
+    },
+    ExpectedValue {
+        found: Register,
+        position: Span,
+    },
+    RegisterIndexOutOfBounds {
+        index: usize,
+        position: Span,
+    },
+
+    // Local errors
+    UndefinedLocal {
+        local_index: u8,
+        position: Span,
+    },
+
+    // Execution errors
+    ExpectedBoolean {
+        found: Value,
+        position: Span,
+    },
+    ExpectedFunction {
+        found: ConcreteValue,
+        position: Span,
+    },
+    ExpectedParent {
+        position: Span,
+    },
+    ValueDisplay {
+        error: io::ErrorKind,
+        position: Span,
+    },
+
+    // Chunk errors
+    ConstantIndexOutOfBounds {
+        index: usize,
+        position: Span,
+    },
+    InstructionIndexOutOfBounds {
+        index: usize,
+        position: Span,
+    },
+    LocalIndexOutOfBounds {
+        index: usize,
+        position: Span,
+    },
+
+    // Wrappers for foreign errors
+    NativeFunction(NativeFunctionError),
+    Value {
+        error: ValueError,
+        position: Span,
+    },
+}
+
+impl AnnotatedError for VmError {
+    fn title() -> &'static str {
+        "Runtime Error"
+    }
+
+    fn description(&self) -> &'static str {
+        match self {
+            Self::ConstantIndexOutOfBounds { .. } => "Constant index out of bounds",
+            Self::EmptyRegister { .. } => "Empty register",
+            Self::ExpectedBoolean { .. } => "Expected boolean",
+            Self::ExpectedConcreteValue { .. } => "Expected concrete value",
+            Self::ExpectedFunction { .. } => "Expected function",
+            Self::ExpectedParent { .. } => "Expected parent",
+            Self::ExpectedValue { .. } => "Expected value",
+            Self::InstructionIndexOutOfBounds { .. } => "Instruction index out of bounds",
+            Self::LocalIndexOutOfBounds { .. } => "Local index out of bounds",
+            Self::NativeFunction(error) => error.description(),
+            Self::RegisterIndexOutOfBounds { .. } => "Register index out of bounds",
+            Self::StackOverflow { .. } => "Stack overflow",
+            Self::StackUnderflow { .. } => "Stack underflow",
+            Self::UndefinedLocal { .. } => "Undefined local",
+            Self::Value { .. } => "Value error",
+            Self::ValueDisplay { .. } => "Value display error",
+        }
+    }
+
+    fn detail_snippets(&self) -> SmallVec<[(String, Span); 2]> {
+        match self {
+            VmError::StackOverflow { position } => todo!(),
+            VmError::StackUnderflow { position } => todo!(),
+            VmError::EmptyRegister { index, position } => todo!(),
+            VmError::ExpectedConcreteValue { found, position } => todo!(),
+            VmError::ExpectedValue { found, position } => todo!(),
+            VmError::RegisterIndexOutOfBounds { index, position } => todo!(),
+            VmError::UndefinedLocal {
+                local_index,
+                position,
+            } => todo!(),
+            VmError::ExpectedBoolean { found, position } => todo!(),
+            VmError::ExpectedFunction { found, position } => todo!(),
+            VmError::ExpectedParent { position } => todo!(),
+            VmError::ValueDisplay { error, position } => todo!(),
+            VmError::ConstantIndexOutOfBounds { index, position } => todo!(),
+            VmError::InstructionIndexOutOfBounds { index, position } => todo!(),
+            VmError::LocalIndexOutOfBounds { index, position } => todo!(),
+            VmError::NativeFunction(native_function_error) => todo!(),
+            VmError::Value { error, position } => todo!(),
+        }
+    }
+
+    fn help_snippets(&self) -> SmallVec<[(String, Span); 2]> {
+        todo!()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const ALL_OPERATIONS: [(Operation, Runner); 24] = [
+        (Operation::MOVE, runners::r#move),
+        (Operation::CLOSE, runners::close),
+        (Operation::LOAD_BOOLEAN, runners::load_boolean),
+        (Operation::LOAD_CONSTANT, runners::load_constant),
+        (Operation::LOAD_LIST, runners::load_list),
+        (Operation::LOAD_SELF, runners::load_self),
+        (Operation::GET_LOCAL, runners::get_local),
+        (Operation::SET_LOCAL, runners::set_local),
+        (Operation::ADD, runners::add),
+        (Operation::SUBTRACT, runners::subtract),
+        (Operation::MULTIPLY, runners::multiply),
+        (Operation::DIVIDE, runners::divide),
+        (Operation::MODULO, runners::modulo),
+        (Operation::TEST, runners::test),
+        (Operation::TEST_SET, runners::test_set),
+        (Operation::EQUAL, runners::equal),
+        (Operation::LESS, runners::less),
+        (Operation::LESS_EQUAL, runners::less_equal),
+        (Operation::NEGATE, runners::negate),
+        (Operation::NOT, runners::not),
+        (Operation::CALL, runners::call),
+        (Operation::CALL_NATIVE, runners::call_native),
+        (Operation::JUMP, runners::jump),
+        (Operation::RETURN, runners::r#return),
+    ];
+
+    #[test]
+    fn operations_map_to_the_correct_runner() {
+        for (operation, expected_runner) in ALL_OPERATIONS {
+            let actual_runner = RUNNERS[operation.0 as usize];
+
+            assert_eq!(
+                expected_runner, actual_runner,
+                "{operation} runner is incorrect"
+            );
+        }
+    }
+}

dust-lang/src/vm/runners.rs

@@ -0,0 +1,528 @@
+use smallvec::SmallVec;
+
+use crate::{AbstractValue, ConcreteValue, NativeFunction, Value, ValueRef};
+
+use super::{InstructionData, Pointer, Register, Vm};
+
+pub type Runner = fn(&mut Vm, InstructionData);
+
+pub const RUNNERS: [Runner; 24] = [
+    r#move,
+    close,
+    load_boolean,
+    load_constant,
+    load_list,
+    load_self,
+    get_local,
+    set_local,
+    add,
+    subtract,
+    multiply,
+    divide,
+    modulo,
+    test,
+    test_set,
+    equal,
+    less,
+    less_equal,
+    negate,
+    not,
+    call,
+    call_native,
+    jump,
+    r#return,
+];
+
+#[allow(clippy::needless_lifetimes)]
+pub fn r#move<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { b, c, .. } = instruction_data;
+    let from_register_has_value = vm
+        .stack
+        .get(b as usize)
+        .is_some_and(|register| !matches!(register, Register::Empty));
+    let register = Register::Pointer(Pointer::Stack(b));
+
+    if from_register_has_value {
+        vm.set_register(c, register);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn close<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { b, c, .. } = instruction_data;
+
+    assert!(b < c, "Runtime Error: Malformed instruction");
+
+    for register_index in b..c {
+        assert!(
+            (register_index as usize) < vm.stack.len(),
+            "Runtime Error: Register index out of bounds"
+        );
+
+        vm.stack[register_index as usize] = Register::Empty;
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn load_boolean<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { a, b, c, .. } = instruction_data;
+    let boolean = ConcreteValue::Boolean(b != 0).to_value();
+    let register = Register::Value(boolean);
+
+    vm.set_register(a, register);
+
+    if c != 0 {
+        vm.jump_instructions(1, true);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn load_constant<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { a, b, c, .. } = instruction_data;
+    let register = Register::Pointer(Pointer::Constant(b));
+
+    vm.set_register(a, register);
+
+    if c != 0 {
+        vm.jump_instructions(1, true);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn load_list<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { a, b, .. } = instruction_data;
+    let mut item_pointers = Vec::new();
+    let stack = vm.stack.as_slice();
+
+    for register_index in b..a {
+        if let Register::Empty = stack[register_index as usize] {
+            continue;
+        }
+
+        let pointer = Pointer::Stack(register_index);
+
+        item_pointers.push(pointer);
+    }
+
+    let list_value = AbstractValue::List { item_pointers }.to_value();
+    let register = Register::Value(list_value);
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn load_self<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { a, .. } = instruction_data;
+    let register = Register::Value(AbstractValue::FunctionSelf.to_value());
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn get_local<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { a, b, .. } = instruction_data;
+    let local_register_index = vm.get_local_register(b);
+    let register = Register::Pointer(Pointer::Stack(local_register_index));
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn set_local<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { b, c, .. } = instruction_data;
+    let local_register_index = vm.get_local_register(c);
+    let register = Register::Pointer(Pointer::Stack(b));
+
+    vm.set_register(local_register_index, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn add<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let sum = match (left, right) {
+        (ValueRef::Concrete(left), ValueRef::Concrete(right)) => match (left, right) {
+            (ConcreteValue::Integer(left), ConcreteValue::Integer(right)) => {
+                ConcreteValue::Integer(left + right).to_value()
+            }
+            _ => panic!("Value Error: Cannot add values"),
+        },
+        _ => panic!("Value Error: Cannot add values {left} and {right}"),
+    };
+    let register = Register::Value(sum);
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn subtract<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let difference = match (left, right) {
+        (ValueRef::Concrete(left), ValueRef::Concrete(right)) => match (left, right) {
+            (ConcreteValue::Integer(left), ConcreteValue::Integer(right)) => {
+                ConcreteValue::Integer(left - right).to_value()
+            }
+            _ => panic!("Value Error: Cannot subtract values {left} and {right}"),
+        },
+        _ => panic!("Value Error: Cannot subtract values {left} and {right}"),
+    };
+    let register = Register::Value(difference);
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn multiply<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let product = match (left, right) {
+        (ValueRef::Concrete(left), ValueRef::Concrete(right)) => match (left, right) {
+            (ConcreteValue::Integer(left), ConcreteValue::Integer(right)) => {
+                ConcreteValue::Integer(left * right).to_value()
+            }
+            _ => panic!("Value Error: Cannot multiply values"),
+        },
+        _ => panic!("Value Error: Cannot multiply values"),
+    };
+    let register = Register::Value(product);
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn divide<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let quotient = match (left, right) {
+        (ValueRef::Concrete(left), ValueRef::Concrete(right)) => match (left, right) {
+            (ConcreteValue::Integer(left), ConcreteValue::Integer(right)) => {
+                ConcreteValue::Integer(left / right).to_value()
+            }
+            _ => panic!("Value Error: Cannot divide values"),
+        },
+        _ => panic!("Value Error: Cannot divide values"),
+    };
+    let register = Register::Value(quotient);
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn modulo<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let remainder = match (left, right) {
+        (ValueRef::Concrete(left), ValueRef::Concrete(right)) => match (left, right) {
+            (ConcreteValue::Integer(left), ConcreteValue::Integer(right)) => {
+                ConcreteValue::Integer(left % right).to_value()
+            }
+            _ => panic!("Value Error: Cannot modulo values"),
+        },
+        _ => panic!("Value Error: Cannot modulo values"),
+    };
+    let register = Register::Value(remainder);
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn test<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        b,
+        b_is_constant,
+        c,
+        ..
+    } = instruction_data;
+    let value = vm.get_argument(b, b_is_constant);
+    let boolean = if let ValueRef::Concrete(ConcreteValue::Boolean(boolean)) = value {
+        *boolean
+    } else {
+        panic!(
+            "VM Error: Expected boolean value for TEST operation at {}",
+            vm.current_position()
+        );
+    };
+    let test_value = c != 0;
+
+    if boolean == test_value {
+        vm.jump_instructions(1, true);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn test_set<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        ..
+    } = instruction_data;
+    let value = vm.get_argument(b, b_is_constant);
+    let boolean = if let ValueRef::Concrete(ConcreteValue::Boolean(boolean)) = value {
+        *boolean
+    } else {
+        panic!(
+            "VM Error: Expected boolean value for TEST_SET operation at {}",
+            vm.current_position()
+        );
+    };
+    let test_value = c != 0;
+
+    if boolean == test_value {
+        vm.jump_instructions(1, true);
+    } else {
+        let pointer = if b_is_constant {
+            Pointer::Constant(b)
+        } else {
+            Pointer::Stack(b)
+        };
+        let register = Register::Pointer(pointer);
+
+        vm.set_register(a, register);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn equal<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        d,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let is_equal = left == right;
+
+    if is_equal == d {
+        vm.jump_instructions(1, true);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn less<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        d,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let is_less = left < right;
+
+    if is_less == d {
+        vm.jump_instructions(1, true);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn less_equal<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        b,
+        c,
+        b_is_constant,
+        c_is_constant,
+        d,
+        ..
+    } = instruction_data;
+    let left = vm.get_argument(b, b_is_constant);
+    let right = vm.get_argument(c, c_is_constant);
+    let is_less_or_equal = left <= right;
+
+    if is_less_or_equal == d {
+        vm.jump_instructions(1, true);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn negate<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        b_is_constant,
+        ..
+    } = instruction_data;
+    let argument = vm.get_argument(b, b_is_constant);
+    let negated = match argument {
+        ValueRef::Concrete(value) => match value {
+            ConcreteValue::Float(float) => ConcreteValue::Float(-float),
+            ConcreteValue::Integer(integer) => ConcreteValue::Integer(-integer),
+            _ => panic!("Value Error: Cannot negate value"),
+        },
+        ValueRef::Abstract(_) => panic!("VM Error: Cannot negate value"),
+    };
+    let register = Register::Value(Value::Concrete(negated));
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn not<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        b_is_constant,
+        ..
+    } = instruction_data;
+    let argument = vm.get_argument(b, b_is_constant);
+    let not = match argument {
+        ValueRef::Concrete(ConcreteValue::Boolean(boolean)) => ConcreteValue::Boolean(!boolean),
+        _ => panic!("VM Error: Expected boolean value for NOT operation"),
+    };
+    let register = Register::Value(Value::Concrete(not));
+
+    vm.set_register(a, register)
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn jump<'c>(vm: &mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { b, c, .. } = instruction_data;
+    let is_positive = c != 0;
+
+    vm.jump_instructions(b as usize, is_positive);
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn call<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData {
+        a,
+        b,
+        c,
+        b_is_constant,
+        ..
+    } = instruction_data;
+    let function = vm.get_argument(b, b_is_constant);
+    let chunk = if let ValueRef::Concrete(ConcreteValue::Function(chunk)) = function {
+        chunk
+    } else if let ValueRef::Abstract(AbstractValue::FunctionSelf) = function {
+        vm.chunk
+    } else {
+        panic!("VM Error: Expected function")
+    };
+    let mut function_vm = Vm::new(vm.source, chunk, Some(vm));
+    let first_argument_index = a - c;
+    let mut argument_index = 0;
+
+    for argument_register_index in first_argument_index..a {
+        let target_register_is_empty =
+            matches!(vm.stack[argument_register_index as usize], Register::Empty);
+
+        if target_register_is_empty {
+            continue;
+        }
+
+        function_vm.set_register(
+            argument_index as u8,
+            Register::Pointer(Pointer::ParentStack(argument_register_index)),
+        );
+
+        argument_index += 1;
+    }
+
+    let return_value = function_vm.run();
+
+    if let Some(concrete_value) = return_value {
+        let register = Register::Value(concrete_value.to_value());
+
+        vm.set_register(a, register);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn call_native<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let InstructionData { a, b, c, .. } = instruction_data;
+    let first_argument_index = (a - c) as usize;
+    let argument_range = first_argument_index..a as usize;
+    let mut arguments: SmallVec<[ValueRef; 4]> = SmallVec::new();
+
+    for register_index in argument_range {
+        let register = &vm.stack[register_index];
+        let value = match register {
+            Register::Value(value) => value.to_ref(),
+            Register::Pointer(pointer) => {
+                let value_option = vm.follow_pointer_allow_empty(*pointer);
+
+                match value_option {
+                    Some(value) => value,
+                    None => continue,
+                }
+            }
+            Register::Empty => continue,
+        };
+
+        arguments.push(value);
+    }
+
+    let function = NativeFunction::from(b);
+    let return_value = function.call(vm, arguments).unwrap();
+
+    if let Some(value) = return_value {
+        let register = Register::Value(value);
+
+        vm.set_register(a, register);
+    }
+}
+
+#[allow(clippy::needless_lifetimes)]
+pub fn r#return<'b, 'c>(vm: &'b mut Vm<'c>, instruction_data: InstructionData) {
+    let should_return_value = instruction_data.b != 0;
+
+    if !should_return_value {
+        return;
+    }
+
+    if let Some(register_index) = &vm.last_assigned_register {
+        let return_value = vm.open_register(*register_index).into_concrete_owned(vm);
+
+        vm.return_value = Some(return_value);
+    } else {
+        panic!("Stack underflow");
+    }
+}