Files
stationeers_lang/libs/compiler/src/v1.rs

893 lines
33 KiB
Rust

use crate::variable_manager::{self, LocationRequest, VariableLocation, VariableScope};
use parser::{
Parser as ASTParser,
tree_node::{
BinaryExpression, BlockExpression, DeviceDeclarationExpression, Expression,
FunctionExpression, InvocationExpression, Literal, LogicalExpression,
},
};
use quick_error::quick_error;
use std::{
collections::HashMap,
io::{BufWriter, Write},
};
macro_rules! debug {
($self: expr, $debug_value: expr) => {
if $self.config.debug {
format!($debug_value)
} else {
"".into()
}
};
}
quick_error! {
#[derive(Debug)]
pub enum Error {
ParseError(error: parser::Error) {
from()
}
IoError(error: std::io::Error) {
from()
}
ScopeError(error: variable_manager::Error) {
from()
}
DuplicateIdentifier(func_name: String) {
display("`{func_name}` has already been defined")
}
UnknownIdentifier(ident: String) {
display("`{ident}` is not found in the current scope.")
}
InvalidDevice(device: String) {
display("`{device}` is not valid")
}
AgrumentMismatch(func_name: String) {
display("Incorrect number of arguments passed into `{func_name}`")
}
Unknown(reason: String) {
display("{reason}")
}
}
}
#[derive(Default)]
#[repr(C)]
pub struct CompilerConfig {
pub debug: bool,
}
struct CompilationResult {
location: VariableLocation,
/// If Some, this is the name of the temporary variable that holds the result.
/// It must be freed by the caller when done.
temp_name: Option<String>,
}
pub struct Compiler<'a, W: std::io::Write> {
parser: ASTParser,
function_locations: HashMap<String, usize>,
function_metadata: HashMap<String, Vec<String>>,
devices: HashMap<String, String>,
output: &'a mut BufWriter<W>,
current_line: usize,
declared_main: bool,
config: CompilerConfig,
temp_counter: usize,
}
impl<'a, W: std::io::Write> Compiler<'a, W> {
pub fn new(
parser: ASTParser,
writer: &'a mut BufWriter<W>,
config: Option<CompilerConfig>,
) -> Self {
Self {
parser,
function_locations: HashMap::new(),
function_metadata: HashMap::new(),
devices: HashMap::new(),
output: writer,
current_line: 1,
declared_main: false,
config: config.unwrap_or_default(),
temp_counter: 0,
}
}
pub fn compile(mut self) -> Result<(), Error> {
let expr = self.parser.parse_all()?;
let Some(expr) = expr else { return Ok(()) };
self.write_output("j main")?;
// We ignore the result of the root expression (usually a block)
let _ = self.expression(expr, &mut VariableScope::default())?;
Ok(())
}
fn write_output(&mut self, output: impl Into<String>) -> Result<(), Error> {
self.output.write_all(output.into().as_bytes())?;
self.output.write_all(b"\n")?;
self.current_line += 1;
Ok(())
}
fn next_temp_name(&mut self) -> String {
self.temp_counter += 1;
format!("__binary_temp_{}", self.temp_counter)
}
fn expression<'v>(
&mut self,
expr: Expression,
scope: &mut VariableScope<'v>,
) -> Result<Option<CompilationResult>, Error> {
match expr {
Expression::Function(expr_func) => {
self.expression_function(expr_func, scope)?;
Ok(None)
}
Expression::Block(expr_block) => {
self.expression_block(expr_block, scope)?;
Ok(None)
}
Expression::DeviceDeclaration(expr_dev) => {
self.expression_device(expr_dev)?;
Ok(None)
}
Expression::Declaration(var_name, expr) => {
let loc = self.expression_declaration(var_name, *expr, scope)?;
Ok(loc.map(|l| CompilationResult {
location: l,
temp_name: None,
}))
}
Expression::Invocation(expr_invoke) => {
self.expression_function_invocation(expr_invoke, scope)?;
// Invocation returns result in r15 (RETURN_REGISTER).
// If used as an expression, we must move it to a temp to avoid overwrite.
let temp_name = self.next_temp_name();
let temp_loc = scope.add_variable(&temp_name, LocationRequest::Temp)?;
self.emit_variable_assignment(
&temp_name,
&temp_loc,
format!("r{}", VariableScope::RETURN_REGISTER),
)?;
Ok(Some(CompilationResult {
location: temp_loc,
temp_name: Some(temp_name),
}))
}
Expression::Binary(bin_expr) => {
let result = self.expression_binary(bin_expr, scope)?;
Ok(Some(result))
}
Expression::Logical(log_expr) => {
let result = self.expression_logical(log_expr, scope)?;
Ok(Some(result))
}
Expression::Literal(Literal::Number(num)) => {
let temp_name = self.next_temp_name();
let loc = scope.add_variable(&temp_name, LocationRequest::Temp)?;
self.emit_variable_assignment(&temp_name, &loc, num.to_string())?;
Ok(Some(CompilationResult {
location: loc,
temp_name: Some(temp_name),
}))
}
Expression::Literal(Literal::Boolean(b)) => {
let val = if b { "1" } else { "0" };
let temp_name = self.next_temp_name();
let loc = scope.add_variable(&temp_name, LocationRequest::Temp)?;
self.emit_variable_assignment(&temp_name, &loc, val)?;
Ok(Some(CompilationResult {
location: loc,
temp_name: Some(temp_name),
}))
}
Expression::Variable(name) => {
let loc = scope.get_location_of(&name)?;
Ok(Some(CompilationResult {
location: loc,
temp_name: None, // User variable, do not free
}))
}
Expression::Priority(inner_expr) => self.expression(*inner_expr, scope),
Expression::Negation(inner_expr) => {
// Compile negation as 0 - inner
let (inner_str, cleanup) = self.compile_operand(*inner_expr, scope)?;
let result_name = self.next_temp_name();
let result_loc = scope.add_variable(&result_name, LocationRequest::Temp)?;
let result_reg = self.resolve_register(&result_loc)?;
self.write_output(format!("sub {result_reg} 0 {inner_str}"))?;
if let Some(name) = cleanup {
scope.free_temp(name)?;
}
Ok(Some(CompilationResult {
location: result_loc,
temp_name: Some(result_name),
}))
}
_ => Err(Error::Unknown(format!(
"Expression type not yet supported in general expression context: {:?}",
expr
))),
}
}
fn emit_variable_assignment(
&mut self,
var_name: &str,
location: &VariableLocation,
source_value: impl Into<String>,
) -> Result<(), Error> {
let debug_tag = if self.config.debug {
format!(" #{var_name}")
} else {
String::new()
};
match location {
VariableLocation::Temporary(reg) | VariableLocation::Persistant(reg) => {
self.write_output(format!("move r{reg} {}{debug_tag}", source_value.into()))?;
}
VariableLocation::Stack(_) => {
self.write_output(format!("push {}{debug_tag}", source_value.into()))?;
}
}
Ok(())
}
fn expression_declaration<'v>(
&mut self,
var_name: String,
expr: Expression,
scope: &mut VariableScope<'v>,
) -> Result<Option<VariableLocation>, Error> {
// optimization. Check for a negated numeric literal
if let Expression::Negation(box_expr) = &expr
&& let Expression::Literal(Literal::Number(neg_num)) = &**box_expr
{
let loc = scope.add_variable(&var_name, LocationRequest::Persist)?;
self.emit_variable_assignment(&var_name, &loc, format!("-{neg_num}"))?;
return Ok(Some(loc));
}
let loc = match expr {
Expression::Literal(Literal::Number(num)) => {
let var_location =
scope.add_variable(var_name.clone(), LocationRequest::Persist)?;
self.emit_variable_assignment(&var_name, &var_location, num)?;
var_location
}
Expression::Literal(Literal::Boolean(b)) => {
let val = if b { "1" } else { "0" };
let var_location =
scope.add_variable(var_name.clone(), LocationRequest::Persist)?;
self.emit_variable_assignment(&var_name, &var_location, val)?;
var_location
}
Expression::Invocation(invoke_expr) => {
self.expression_function_invocation(invoke_expr, scope)?;
let loc = scope.add_variable(&var_name, LocationRequest::Persist)?;
self.emit_variable_assignment(
&var_name,
&loc,
format!("r{}", VariableScope::RETURN_REGISTER),
)?;
loc
}
// Support assigning binary expressions to variables directly
Expression::Binary(bin_expr) => {
let result = self.expression_binary(bin_expr, scope)?;
let var_loc = scope.add_variable(&var_name, LocationRequest::Persist)?;
// Move result from temp to new persistent variable
let result_reg = self.resolve_register(&result.location)?;
self.emit_variable_assignment(&var_name, &var_loc, result_reg)?;
// Free the temp result
if let Some(name) = result.temp_name {
scope.free_temp(name)?;
}
var_loc
}
Expression::Logical(log_expr) => {
let result = self.expression_logical(log_expr, scope)?;
let var_loc = scope.add_variable(&var_name, LocationRequest::Persist)?;
// Move result from temp to new persistent variable
let result_reg = self.resolve_register(&result.location)?;
self.emit_variable_assignment(&var_name, &var_loc, result_reg)?;
// Free the temp result
if let Some(name) = result.temp_name {
scope.free_temp(name)?;
}
var_loc
}
Expression::Variable(name) => {
let src_loc = scope.get_location_of(&name)?;
let var_loc = scope.add_variable(&var_name, LocationRequest::Persist)?;
// Handle loading from stack if necessary
let src_str = match src_loc {
VariableLocation::Temporary(r) | VariableLocation::Persistant(r) => {
format!("r{r}")
}
VariableLocation::Stack(offset) => {
self.write_output(format!(
"sub r{0} sp {offset}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"get r{0} db r{0}",
VariableScope::TEMP_STACK_REGISTER
))?;
format!("r{}", VariableScope::TEMP_STACK_REGISTER)
}
};
self.emit_variable_assignment(&var_name, &var_loc, src_str)?;
var_loc
}
Expression::Priority(inner) => {
return self.expression_declaration(var_name, *inner, scope);
}
_ => {
return Err(Error::Unknown(format!(
"`{var_name}` declaration of this type is not supported/implemented."
)));
}
};
Ok(Some(loc))
}
fn expression_function_invocation(
&mut self,
invoke_expr: InvocationExpression,
stack: &mut VariableScope,
) -> Result<(), Error> {
if !self.function_locations.contains_key(&invoke_expr.name) {
return Err(Error::UnknownIdentifier(invoke_expr.name));
}
let Some(args) = self.function_metadata.get(&invoke_expr.name) else {
return Err(Error::UnknownIdentifier(invoke_expr.name));
};
if args.len() != invoke_expr.arguments.len() {
return Err(Error::AgrumentMismatch(invoke_expr.name));
}
// backup all used registers to the stack
let active_registers = stack.registers().cloned().collect::<Vec<_>>();
for register in &active_registers {
stack.add_variable(format!("temp_{register}"), LocationRequest::Stack)?;
self.write_output(format!("push r{register}"))?;
}
for arg in invoke_expr.arguments {
match arg {
Expression::Literal(Literal::Number(num)) => {
let num_str = num.to_string();
self.write_output(format!("push {num_str}"))?;
}
Expression::Literal(Literal::Boolean(b)) => {
let val = if b { "1" } else { "0" };
self.write_output(format!("push {val}"))?;
}
Expression::Variable(var_name) => match stack.get_location_of(var_name)? {
VariableLocation::Persistant(reg) | VariableLocation::Temporary(reg) => {
self.write_output(format!("push r{reg}"))?;
}
VariableLocation::Stack(stack_offset) => {
self.write_output(format!(
"sub r{0} sp {stack_offset}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"get r{0} db r{0}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"push r{0}",
VariableScope::TEMP_STACK_REGISTER
))?;
}
},
Expression::Binary(bin_expr) => {
// Compile the binary expression to a temp register
let result = self.expression_binary(bin_expr, stack)?;
let reg_str = self.resolve_register(&result.location)?;
self.write_output(format!("push {reg_str}"))?;
if let Some(name) = result.temp_name {
stack.free_temp(name)?;
}
}
Expression::Logical(log_expr) => {
// Compile the logical expression to a temp register
let result = self.expression_logical(log_expr, stack)?;
let reg_str = self.resolve_register(&result.location)?;
self.write_output(format!("push {reg_str}"))?;
if let Some(name) = result.temp_name {
stack.free_temp(name)?;
}
}
_ => {
return Err(Error::Unknown(format!(
"Attempted to call `{}` with an unsupported argument type",
invoke_expr.name
)));
}
}
}
// jump to the function and store current line in ra
self.write_output(format!("jal {}", invoke_expr.name))?;
for register in active_registers {
let VariableLocation::Stack(stack_offset) =
stack.get_location_of(format!("temp_{register}"))?
else {
return Err(Error::UnknownIdentifier(format!("temp_{register}")));
};
self.write_output(format!(
"sub r{0} sp {stack_offset}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"get r{register} db r{0}",
VariableScope::TEMP_STACK_REGISTER
))?;
}
if stack.stack_offset() > 0 {
self.write_output(format!("sub sp sp {}", stack.stack_offset()))?;
}
Ok(())
}
fn expression_device(&mut self, expr: DeviceDeclarationExpression) -> Result<(), Error> {
if self.devices.contains_key(&expr.name) {
return Err(Error::DuplicateIdentifier(expr.name));
}
self.devices.insert(expr.name, expr.device);
Ok(())
}
/// Helper to resolve a location to a register string (e.g., "r0").
/// Note: This does not handle Stack locations automatically, as they require
/// instruction emission to load. Use `compile_operand` for general handling.
fn resolve_register(&self, loc: &VariableLocation) -> Result<String, Error> {
match loc {
VariableLocation::Temporary(r) | VariableLocation::Persistant(r) => Ok(format!("r{r}")),
VariableLocation::Stack(_) => Err(Error::Unknown(
"Cannot resolve Stack location directly to register string without context".into(),
)),
}
}
/// Compiles an expression and ensures the result is available as a string valid for an
/// IC10 operand (either a register "rX" or a literal value "123").
/// If the result was stored in a new temporary register, returns the name of that temp
/// so the caller can free it.
fn compile_operand(
&mut self,
expr: Expression,
scope: &mut VariableScope,
) -> Result<(String, Option<String>), Error> {
// Optimization for literals
if let Expression::Literal(Literal::Number(n)) = expr {
return Ok((n.to_string(), None));
}
// Optimization for boolean literals
if let Expression::Literal(Literal::Boolean(b)) = expr {
return Ok((if b { "1".to_string() } else { "0".to_string() }, None));
}
// Optimization for negated literals used as operands.
// E.g., `1 + -2` -> return "-2" string, no register used.
if let Expression::Negation(inner) = &expr
&& let Expression::Literal(Literal::Number(n)) = &**inner
{
return Ok((format!("-{}", n), None));
}
let result = self
.expression(expr, scope)?
.ok_or(Error::Unknown("Expression did not return a value".into()))?;
match result.location {
VariableLocation::Temporary(r) | VariableLocation::Persistant(r) => {
Ok((format!("r{r}"), result.temp_name))
}
VariableLocation::Stack(offset) => {
// If it's on the stack, we must load it into a temp to use it as an operand
let temp_name = self.next_temp_name();
let temp_loc = scope.add_variable(&temp_name, LocationRequest::Temp)?;
let temp_reg = self.resolve_register(&temp_loc)?;
self.write_output(format!(
"sub r{0} sp {offset}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"get {temp_reg} db r{0}",
VariableScope::TEMP_STACK_REGISTER
))?;
// If the original result had a temp name (unlikely for Stack, but possible logic),
// we technically should free it if it's not needed, but Stack usually implies it's safe there.
// We return the NEW temp name to be freed.
Ok((temp_reg, Some(temp_name)))
}
}
}
fn expression_binary<'v>(
&mut self,
expr: BinaryExpression,
scope: &mut VariableScope<'v>,
) -> Result<CompilationResult, Error> {
let (op_str, left_expr, right_expr) = match expr {
BinaryExpression::Add(l, r) => ("add", l, r),
BinaryExpression::Multiply(l, r) => ("mul", l, r),
BinaryExpression::Divide(l, r) => ("div", l, r),
BinaryExpression::Subtract(l, r) => ("sub", l, r),
BinaryExpression::Exponent(l, r) => ("pow", l, r),
BinaryExpression::Modulo(l, r) => ("mod", l, r),
};
// Compile LHS
let (lhs_str, lhs_cleanup) = self.compile_operand(*left_expr, scope)?;
// Compile RHS
let (rhs_str, rhs_cleanup) = self.compile_operand(*right_expr, scope)?;
// Allocate result register
let result_name = self.next_temp_name();
let result_loc = scope.add_variable(&result_name, LocationRequest::Temp)?;
let result_reg = self.resolve_register(&result_loc)?;
// Emit instruction: op result lhs rhs
self.write_output(format!("{op_str} {result_reg} {lhs_str} {rhs_str}"))?;
// Clean up operand temps
if let Some(name) = lhs_cleanup {
scope.free_temp(name)?;
}
if let Some(name) = rhs_cleanup {
scope.free_temp(name)?;
}
Ok(CompilationResult {
location: result_loc,
temp_name: Some(result_name),
})
}
fn expression_logical<'v>(
&mut self,
expr: LogicalExpression,
scope: &mut VariableScope<'v>,
) -> Result<CompilationResult, Error> {
match expr {
LogicalExpression::Not(inner) => {
let (inner_str, cleanup) = self.compile_operand(*inner, scope)?;
let result_name = self.next_temp_name();
let result_loc = scope.add_variable(&result_name, LocationRequest::Temp)?;
let result_reg = self.resolve_register(&result_loc)?;
// seq rX rY 0 => if rY == 0 set rX = 1 else rX = 0
self.write_output(format!("seq {result_reg} {inner_str} 0"))?;
if let Some(name) = cleanup {
scope.free_temp(name)?;
}
Ok(CompilationResult {
location: result_loc,
temp_name: Some(result_name),
})
}
_ => {
let (op_str, left_expr, right_expr) = match expr {
LogicalExpression::And(l, r) => ("and", l, r),
LogicalExpression::Or(l, r) => ("or", l, r),
LogicalExpression::Equal(l, r) => ("seq", l, r),
LogicalExpression::NotEqual(l, r) => ("sne", l, r),
LogicalExpression::GreaterThan(l, r) => ("sgt", l, r),
LogicalExpression::GreaterThanOrEqual(l, r) => ("sge", l, r),
LogicalExpression::LessThan(l, r) => ("slt", l, r),
LogicalExpression::LessThanOrEqual(l, r) => ("sle", l, r),
LogicalExpression::Not(_) => unreachable!(),
};
// Compile LHS
let (lhs_str, lhs_cleanup) = self.compile_operand(*left_expr, scope)?;
// Compile RHS
let (rhs_str, rhs_cleanup) = self.compile_operand(*right_expr, scope)?;
// Allocate result register
let result_name = self.next_temp_name();
let result_loc = scope.add_variable(&result_name, LocationRequest::Temp)?;
let result_reg = self.resolve_register(&result_loc)?;
// Emit instruction: op result lhs rhs
self.write_output(format!("{op_str} {result_reg} {lhs_str} {rhs_str}"))?;
// Clean up operand temps
if let Some(name) = lhs_cleanup {
scope.free_temp(name)?;
}
if let Some(name) = rhs_cleanup {
scope.free_temp(name)?;
}
Ok(CompilationResult {
location: result_loc,
temp_name: Some(result_name),
})
}
}
}
fn expression_block<'v>(
&mut self,
mut expr: BlockExpression,
scope: &mut VariableScope<'v>,
) -> Result<(), Error> {
// First, sort the expressions to ensure functions are hoisted
expr.0.sort_by(|a, b| {
if matches!(b, Expression::Function(_)) && matches!(a, Expression::Function(_)) {
std::cmp::Ordering::Equal
} else if matches!(a, Expression::Function(_)) {
std::cmp::Ordering::Less
} else {
std::cmp::Ordering::Greater
}
});
for expr in expr.0 {
if !self.declared_main
&& !matches!(expr, Expression::Function(_))
&& !scope.has_parent()
{
self.write_output("main:")?;
self.declared_main = true;
}
match expr {
Expression::Return(ret_expr) => {
self.expression_return(*ret_expr, scope)?;
}
_ => {
let result = self.expression(expr, scope)?;
// If the expression was a statement that returned a temp result (e.g. `1 + 2;` line),
// we must free it to avoid leaking registers.
if let Some(comp_res) = result
&& let Some(name) = comp_res.temp_name
{
scope.free_temp(name)?;
}
}
}
}
Ok(())
}
/// Takes the result of the expression and stores it in VariableScope::RETURN_REGISTER
fn expression_return<'v>(
&mut self,
expr: Expression,
scope: &mut VariableScope<'v>,
) -> Result<VariableLocation, Error> {
if let Expression::Negation(neg_expr) = &expr
&& let Expression::Literal(Literal::Number(neg_num)) = &**neg_expr
{
let loc = VariableLocation::Persistant(VariableScope::RETURN_REGISTER);
self.emit_variable_assignment("returnValue", &loc, format!("-{neg_num}"))?;
return Ok(loc);
};
match expr {
Expression::Variable(var_name) => match scope.get_location_of(var_name)? {
VariableLocation::Temporary(reg) | VariableLocation::Persistant(reg) => {
self.write_output(format!(
"move r{} r{reg} {}",
VariableScope::RETURN_REGISTER,
debug!(self, "#returnValue")
))?;
}
VariableLocation::Stack(offset) => {
self.write_output(format!(
"sub r{} sp {offset}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"get r{} db r{}",
VariableScope::RETURN_REGISTER,
VariableScope::TEMP_STACK_REGISTER
))?;
}
},
Expression::Literal(Literal::Number(num)) => {
self.emit_variable_assignment(
"returnValue",
&VariableLocation::Persistant(VariableScope::RETURN_REGISTER),
num,
)?;
}
Expression::Literal(Literal::Boolean(b)) => {
let val = if b { "1" } else { "0" };
self.emit_variable_assignment(
"returnValue",
&VariableLocation::Persistant(VariableScope::RETURN_REGISTER),
val,
)?;
}
Expression::Binary(bin_expr) => {
let result = self.expression_binary(bin_expr, scope)?;
let result_reg = self.resolve_register(&result.location)?;
self.write_output(format!(
"move r{} {}",
VariableScope::RETURN_REGISTER,
result_reg
))?;
if let Some(name) = result.temp_name {
scope.free_temp(name)?;
}
}
Expression::Logical(log_expr) => {
let result = self.expression_logical(log_expr, scope)?;
let result_reg = self.resolve_register(&result.location)?;
self.write_output(format!(
"move r{} {}",
VariableScope::RETURN_REGISTER,
result_reg
))?;
if let Some(name) = result.temp_name {
scope.free_temp(name)?;
}
}
_ => {
return Err(Error::Unknown(format!(
"Unsupported `return` statement: {:?}",
expr
)));
}
}
Ok(VariableLocation::Persistant(VariableScope::RETURN_REGISTER))
}
/// Compile a function declaration.
/// Calees are responsible for backing up any registers they wish to use.
fn expression_function<'v>(
&mut self,
expr: FunctionExpression,
scope: &mut VariableScope<'v>,
) -> Result<(), Error> {
let FunctionExpression {
name,
arguments,
body,
} = expr;
if self.function_locations.contains_key(&name) {
return Err(Error::DuplicateIdentifier(name));
}
self.function_metadata
.insert(name.clone(), arguments.clone());
// Declare the function as a line identifier
self.write_output(format!("{}:", name))?;
self.function_locations
.insert(name.clone(), self.current_line);
// Create a new block scope for the function body
let mut block_scope = VariableScope::scoped(scope);
let mut saved_variables = 0;
// do a reverse pass to pop variables from the stack and put them into registers
for var_name in arguments
.iter()
.rev()
.take(VariableScope::PERSIST_REGISTER_COUNT as usize)
{
let loc = block_scope.add_variable(var_name, LocationRequest::Persist)?;
// we don't need to imcrement the stack offset as it's already on the stack from the
// previous scope
match loc {
VariableLocation::Persistant(loc) => {
self.write_output(format!("pop r{loc} {}", debug!(self, "#{var_name}")))?;
}
VariableLocation::Stack(_) => {
return Err(Error::Unknown(
"Attempted to save to stack without tracking in scope".into(),
));
}
_ => {
return Err(Error::Unknown(
"Attempted to return a Temporary scoped variable from a Persistant request"
.into(),
));
}
}
saved_variables += 1;
}
// now do a forward pass in case we have spilled into the stack. We don't need to push
// anything as they already exist on the stack, but we DO need to let our block_scope be
// aware that the variables exist on the stack (left to right)
for var_name in arguments.iter().take(arguments.len() - saved_variables) {
block_scope.add_variable(var_name, LocationRequest::Stack)?;
}
self.write_output("push ra")?;
block_scope.add_variable(format!("{name}_ra"), LocationRequest::Stack)?;
for expr in body.0 {
match expr {
Expression::Return(ret_expr) => {
self.expression_return(*ret_expr, &mut block_scope)?;
}
_ => {
let result = self.expression(expr, &mut block_scope)?;
// Free unused statement results
if let Some(comp_res) = result
&& let Some(name) = comp_res.temp_name
{
block_scope.free_temp(name)?;
}
}
}
}
// Get the saved return address and save it back into `ra`
let VariableLocation::Stack(ra_stack_offset) =
block_scope.get_location_of(format!("{name}_ra"))?
else {
return Err(Error::Unknown(
"Stored return address not in stack as expected".into(),
));
};
self.write_output(format!(
"sub r{0} sp {ra_stack_offset}",
VariableScope::TEMP_STACK_REGISTER
))?;
self.write_output(format!(
"get ra db r{0}",
VariableScope::TEMP_STACK_REGISTER
))?;
if block_scope.stack_offset() > 0 {
self.write_output(format!("sub sp sp {}", block_scope.stack_offset()))?;
}
self.write_output("j ra")?;
Ok(())
}
}