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feat: add foreign function support

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This commit is contained in:
Jooris Hadeler
2026-04-22 22:56:39 +02:00
parent 041a49e574
commit 8bcae8cb31
13 changed files with 368 additions and 46 deletions
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PLAN.md
+3 -3
View File
@@ -49,9 +49,9 @@ A Rust-flavored, C-targeting language - built pipeline-first.
To successfully write a simple ray tracer, we need continuous math, data structures, and I/O. The following path establishes these prerequisites:
- [ ] **Floating-Point Support:** Add `f32`/`f64` types, decimal literals, and Cranelift lowering for `fadd`, `fmul`, etc.
- [ ] **FFI & Interop:** Implement `extern fn` declarations to bind C standard library functions (like `putchar` or `printf`) for `.ppm` image output.
- [ ] **Type Casting:** Add the `as` operator to convert floating-point color bounds `[0.0, 1.0]` into integer byte formats `[0, 255]`.
- [x] **Floating-Point Support:** Add `f32`/`f64` types, decimal literals, and Cranelift lowering for `fadd`, `fmul`, etc.
- [x] **FFI & Interop:** Implement `extern fn` declarations to bind C standard library functions (like `putchar` or `printf`) for `.ppm` image output.
- [x] **Type Casting:** Add the `as` operator to convert floating-point color bounds `[0.0, 1.0]` into integer byte formats `[0, 255]`.
- [ ] **Pointers:** Add pointer types (`*T`), address-of (`&`), and dereference (`*`) operators.
- [ ] **Structs:** Add `struct` definitions, initializers, and field access (`ray.origin.x`) to represent 3D vectors, rays, and spheres.
- [ ] **Arrays:** Add fixed-size arrays (`[T; N]`) or heap allocations for the scene and framebuffers.
runner.py
+12
View File
@@ -12,6 +12,7 @@ def run_test(test_file: Path, compiler_bin: Path):
expected_code = 0
code_lines = []
harness_lines = None
expected_output_lines = None
current_section = None
for line in lines:
@@ -20,6 +21,8 @@ def run_test(test_file: Path, compiler_bin: Path):
current_section = trimmed[1:-1]
if current_section == "harness":
harness_lines = []
elif current_section == "expected_output":
expected_output_lines = []
elif current_section:
if current_section == "expected_return_code":
if trimmed:
@@ -28,6 +31,8 @@ def run_test(test_file: Path, compiler_bin: Path):
code_lines.append(line)
elif current_section == "harness":
harness_lines.append(line)
elif current_section == "expected_output":
expected_output_lines.append(line)
code = "".join(code_lines)
harness = "".join(harness_lines) if harness_lines is not None else None
@@ -75,6 +80,13 @@ def run_test(test_file: Path, compiler_bin: Path):
if exec_res.returncode != expected_code:
raise Exception(f"Expected return code {expected_code}, but got {exec_res.returncode}")
# 4. Check the standard output if expected_output is provided
if expected_output_lines is not None:
expected_out = "".join(expected_output_lines).strip()
actual_out = exec_res.stdout.strip()
if expected_out != actual_out:
raise Exception(f"Expected output:\n{expected_out}\n\nActual output:\n{actual_out}")
def main():
GREEN = '\033[92m'
RED = '\033[91m'
src/backend/cranelift.rs
+85 -25
View File
@@ -22,6 +22,7 @@ pub struct CraneliftBackend {
ctx: Context,
builder_context: FunctionBuilderContext,
module: ObjectModule,
func_ids: HashMap<String, cranelift_module::FuncId>,
}
impl CraneliftBackend {
@@ -46,6 +47,7 @@ impl CraneliftBackend {
ctx: Context::new(),
builder_context: FunctionBuilderContext::new(),
module: ObjectModule::new(builder),
func_ids: HashMap::new(),
}
}
@@ -55,6 +57,40 @@ impl CraneliftBackend {
pub fn compile_module(mut self, module: &MirModule) -> (String, Vec<u8>) {
let mut ir_output = String::new();
for ext_func in &module.extern_functions {
let mut sig = self.module.make_signature();
for param_ty in &ext_func.params {
sig.params.push(AbiParam::new(Self::lower_type(param_ty)));
}
if ext_func.return_type != Ty::Unit {
sig.returns
.push(AbiParam::new(Self::lower_type(&ext_func.return_type)));
}
let func_id = self
.module
.declare_function(&ext_func.name, Linkage::Import, &sig)
.unwrap();
self.func_ids.insert(ext_func.name.clone(), func_id);
}
for func in &module.functions {
let mut sig = self.module.make_signature();
for param_id in &func.params {
let param_ty = &func.locals[param_id.0].ty;
sig.params.push(AbiParam::new(Self::lower_type(param_ty)));
}
if func.return_type != Ty::Unit {
sig.returns
.push(AbiParam::new(Self::lower_type(&func.return_type)));
}
let func_id = self
.module
.declare_function(&func.name, Linkage::Export, &sig)
.unwrap();
self.func_ids.insert(func.name.clone(), func_id);
}
for func in &module.functions {
self.compile_function(func);
@@ -67,12 +103,8 @@ impl CraneliftBackend {
ir_output.push_str(&format!("; Function: {}\n{}", func.name, self.ctx.func));
ir_output.push('\n');
let func_id = self
.module
.declare_function(&func.name, Linkage::Export, &self.ctx.func.signature)
.unwrap();
self.module.define_function(func_id, &mut self.ctx).unwrap();
let id = self.func_ids[&func.name];
self.module.define_function(id, &mut self.ctx).unwrap();
self.module.clear_context(&mut self.ctx);
}
@@ -115,6 +147,8 @@ impl CraneliftBackend {
var_map,
block_map,
locals: &func.locals,
module: &mut self.module,
func_ids: &self.func_ids,
};
if let Some(first_block) = func.blocks.first() {
@@ -173,6 +207,8 @@ struct FunctionTranslator<'a> {
var_map: HashMap<LocalId, Variable>,
block_map: HashMap<BlockId, ir::Block>,
locals: &'a [LocalDecl],
module: &'a mut ObjectModule,
func_ids: &'a HashMap<String, cranelift_module::FuncId>,
}
impl<'a> FunctionTranslator<'a> {
@@ -180,8 +216,13 @@ impl<'a> FunctionTranslator<'a> {
match &stmt.kind {
StatementKind::Assign(local_id, rvalue) => {
let val = self.translate_rvalue(rvalue);
if let Some(v) = val {
let var = self.var_map[local_id];
self.builder.def_var(var, val);
self.builder.def_var(var, v);
}
}
StatementKind::SideEffect(rvalue) => {
self.translate_rvalue(rvalue);
}
}
}
@@ -250,9 +291,9 @@ impl<'a> FunctionTranslator<'a> {
}
}
fn translate_rvalue(&mut self, rvalue: &Rvalue) -> ir::Value {
fn translate_rvalue(&mut self, rvalue: &Rvalue) -> Option<ir::Value> {
match rvalue {
Rvalue::Use(op) => self.translate_operand(op),
Rvalue::Use(op) => Some(self.translate_operand(op)),
Rvalue::UnaryOp(op, inner) => {
let inner_val = self.translate_operand(inner);
let ty = self.get_operand_type(inner);
@@ -260,17 +301,19 @@ impl<'a> FunctionTranslator<'a> {
match op {
UnaryOp::Neg => {
if ty.is_float() {
self.builder.ins().fneg(inner_val)
Some(self.builder.ins().fneg(inner_val))
} else {
self.builder.ins().ineg(inner_val)
Some(self.builder.ins().ineg(inner_val))
}
}
UnaryOp::Not => {
let cl_ty = CraneliftBackend::lower_type(&ty);
let zero = self.builder.ins().iconst(cl_ty, 0);
Some(
self.builder
.ins()
.icmp(ir::condcodes::IntCC::Equal, inner_val, zero)
.icmp(ir::condcodes::IntCC::Equal, inner_val, zero),
)
}
}
}
@@ -282,7 +325,7 @@ impl<'a> FunctionTranslator<'a> {
let is_signed = matches!(ty, Ty::I8 | Ty::I16 | Ty::I32 | Ty::I64);
let is_float = ty.is_float();
match op {
Some(match op {
BinaryOp::Add => {
if is_float {
self.builder.ins().fadd(lhs_val, rhs_val)
@@ -412,7 +455,7 @@ impl<'a> FunctionTranslator<'a> {
self.builder.ins().icmp(cc, lhs_val, rhs_val)
}
}
}
})
}
Rvalue::Cast(to_ty, inner) => {
let inner_val = self.translate_operand(inner);
@@ -420,7 +463,7 @@ impl<'a> FunctionTranslator<'a> {
let cl_to_ty = CraneliftBackend::lower_type(to_ty);
if from_ty == *to_ty {
inner_val
Some(inner_val)
} else {
match (from_ty.is_float(), to_ty.is_float()) {
(false, false) => {
@@ -430,43 +473,60 @@ impl<'a> FunctionTranslator<'a> {
if to_width > from_width {
if from_ty.is_signed() {
self.builder.ins().sextend(cl_to_ty, inner_val)
Some(self.builder.ins().sextend(cl_to_ty, inner_val))
} else {
self.builder.ins().uextend(cl_to_ty, inner_val)
Some(self.builder.ins().uextend(cl_to_ty, inner_val))
}
} else if to_width < from_width {
self.builder.ins().ireduce(cl_to_ty, inner_val)
Some(self.builder.ins().ireduce(cl_to_ty, inner_val))
} else {
inner_val // e.g. bitcasting between same-sized int and uint
Some(inner_val) // e.g. bitcasting between same-sized int and uint
}
}
(true, true) => {
// Float <-> Float
if to_ty.bit_width() > from_ty.bit_width() {
self.builder.ins().fpromote(cl_to_ty, inner_val)
Some(self.builder.ins().fpromote(cl_to_ty, inner_val))
} else {
self.builder.ins().fdemote(cl_to_ty, inner_val)
Some(self.builder.ins().fdemote(cl_to_ty, inner_val))
}
}
(false, true) => {
// Integer -> Float
if from_ty.is_signed() {
self.builder.ins().fcvt_from_sint(cl_to_ty, inner_val)
Some(self.builder.ins().fcvt_from_sint(cl_to_ty, inner_val))
} else {
self.builder.ins().fcvt_from_uint(cl_to_ty, inner_val)
Some(self.builder.ins().fcvt_from_uint(cl_to_ty, inner_val))
}
}
(true, false) => {
// Float -> Integer
if to_ty.is_signed() {
self.builder.ins().fcvt_to_sint_sat(cl_to_ty, inner_val)
Some(self.builder.ins().fcvt_to_sint_sat(cl_to_ty, inner_val))
} else {
self.builder.ins().fcvt_to_uint_sat(cl_to_ty, inner_val)
Some(self.builder.ins().fcvt_to_uint_sat(cl_to_ty, inner_val))
}
}
}
}
}
Rvalue::Call(name, args, ret_ty) => {
let func_id = self.func_ids[name];
let local_callee = self.module.declare_func_in_func(func_id, self.builder.func);
let mut arg_vals = Vec::new();
for arg in args {
arg_vals.push(self.translate_operand(arg));
}
let call_inst = self.builder.ins().call(local_callee, &arg_vals);
if *ret_ty == Ty::Unit {
None
} else {
Some(self.builder.inst_results(call_inst)[0])
}
}
}
}
}
src/frontend/ast.rs
+10
View File
@@ -57,6 +57,12 @@ pub enum DeclKind<P: Phase = Untyped> {
return_type: P::ReturnType,
body: Stmt<P>,
},
ForeignFunction {
name: String,
name_span: Span,
params: Vec<P::ParamType>,
return_type: P::ReturnType,
},
}
#[derive(Debug, PartialEq, Eq)]
@@ -161,6 +167,10 @@ pub enum ExprKind<P: Phase = Untyped> {
expr: Box<Expr<P>>,
ty: P::CastType,
},
Call {
callee: Box<Expr<P>>,
args: Vec<Expr<P>>,
},
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
src/frontend/lexer.rs
+3 -1
View File
@@ -64,6 +64,7 @@ impl<'src> Lexer<'src> {
match &self.source[start..self.cursor] {
"fn" => TokenKind::Fn,
"foreign" => TokenKind::Foreign,
"if" => TokenKind::If,
"as" => TokenKind::As,
"else" => TokenKind::Else,
@@ -249,7 +250,7 @@ mod test {
#[test]
fn identifiers() {
assert_eq!(
tokenize("HELLO _hello _0@ fn if else return let while break continue as"),
tokenize("HELLO _hello _0@ fn if else return let while break continue as foreign"),
vec![
Token::new(TokenKind::Identifier, "HELLO", Span::new(0, 5)),
Token::new(TokenKind::Identifier, "_hello", Span::new(6, 12)),
@@ -264,6 +265,7 @@ mod test {
Token::new(TokenKind::Break, "break", Span::new(45, 50)),
Token::new(TokenKind::Continue, "continue", Span::new(51, 59)),
Token::new(TokenKind::As, "as", Span::new(60, 62)),
Token::new(TokenKind::Foreign, "foreign", Span::new(63, 70)),
]
)
}
src/frontend/parser.rs
+72
View File
@@ -135,6 +135,7 @@ impl<'src> Parser<'src> {
match peek_token.kind {
TokenKind::Fn => self.parse_function_decl(),
TokenKind::Foreign => self.parse_foreign_function_decl(),
_ => Err(ParseError::new(
format!(
@@ -185,6 +186,45 @@ impl<'src> Parser<'src> {
})
}
/// Parses a foreign function declaration.
///
/// ```ebnf
/// foreign_function_decl = "foreign" "fn" IDENTIFIER "(" function_params ")" [ "->" type ] ";" ;
/// ```
fn parse_foreign_function_decl(&mut self) -> ParseResult<Decl> {
let foreign_token = self.expect(TokenKind::Foreign)?;
self.expect(TokenKind::Fn)?;
let (name, name_span) = {
let ident_token = self.expect(TokenKind::Identifier)?;
(ident_token.text.to_string(), ident_token.span)
};
self.expect(TokenKind::LParen)?;
let params = self.parse_function_params()?;
self.expect(TokenKind::RParen)?;
let return_type = if self.is_peek(TokenKind::Arrow) {
self.advance();
Some(self.parse_type()?)
} else {
None
};
let semi_token = self.expect(TokenKind::Semicolon)?;
let span = foreign_token.span.join(semi_token.span);
Ok(Decl {
kind: DeclKind::ForeignFunction {
name,
name_span,
params,
return_type,
},
span,
})
}
/// Parses the function parameter list.
///
/// ```ebnf
@@ -581,6 +621,38 @@ impl<'src> Parser<'src> {
continue;
}
if peek_token.kind == TokenKind::LParen {
let left_bp = 30; // Function calls have very high precedence
if left_bp < min_bp {
break;
}
self.advance(); // consume `(`
let mut args = Vec::new();
if !self.is_peek(TokenKind::RParen) {
loop {
args.push(self.parse_expr()?);
if !self.is_peek(TokenKind::Comma) {
break;
}
self.advance(); // consume `,`
}
}
let rparen_token = self.expect(TokenKind::RParen)?;
let span = lhs.span.join(rparen_token.span);
lhs = Expr {
kind: ExprKind::Call {
callee: Box::new(lhs),
args,
},
ty: (),
span,
};
continue;
}
let Some((op, left_bp, right_bp)) = self.infix_operator(peek_token.kind) else {
break; // Not an infix operator
};
src/frontend/sema.rs
+76
View File
@@ -251,6 +251,12 @@ impl Sema {
params,
return_type,
..
}
| DeclKind::ForeignFunction {
name,
params,
return_type,
..
} => {
let param_tys: Vec<Ty> = params.iter().map(|p| Ty::from(&p.ty.kind)).collect();
let ret_ty = return_type
@@ -321,6 +327,31 @@ impl Sema {
span: decl.span,
}
}
DeclKind::ForeignFunction {
name,
name_span,
params,
return_type,
} => {
let typed_params = params
.iter()
.map(|p| (p.name.clone(), Ty::from(&p.ty.kind)))
.collect();
let expected_ret_ty = return_type
.as_ref()
.map(|t| Ty::from(&t.kind))
.unwrap_or(Ty::Unit);
TypedDecl {
kind: TypedDeclKind::ForeignFunction {
name: name.clone(),
name_span: *name_span,
params: typed_params,
return_type: expected_ret_ty,
},
span: decl.span,
}
}
}
}
@@ -663,6 +694,33 @@ impl Sema {
span: expr.span,
}
}
ExprKind::Call { callee, args } => {
let typed_callee = self.analyze_expr(callee);
let mut typed_args = Vec::new();
let mut arg_tys = Vec::new();
for arg in args {
let typed_arg = self.analyze_expr(arg);
arg_tys.push(typed_arg.ty.clone());
typed_args.push(typed_arg);
}
let ret_ty = self.new_var();
let expected_callee_ty = Ty::Function(arg_tys, Box::new(ret_ty.clone()));
if let Err(e) = self.unify(&typed_callee.ty, &expected_callee_ty) {
self.errors.push(SemanticError::new(e, callee.span));
}
TypedExpr {
kind: TypedExprKind::Call {
callee: Box::new(typed_callee),
args: typed_args,
},
ty: ret_ty,
span: expr.span,
}
}
}
}
@@ -690,6 +748,20 @@ impl Sema {
body: self.apply_subst_stmt(body),
}
}
TypedDeclKind::ForeignFunction {
name,
name_span,
params,
return_type,
} => TypedDeclKind::ForeignFunction {
name,
name_span,
params: params
.into_iter()
.map(|(n, ty)| (n, self.apply_subst(&ty)))
.collect(),
return_type: self.apply_subst(&return_type),
},
};
TypedDecl { kind, span }
@@ -775,6 +847,10 @@ impl Sema {
expr: Box::new(self.apply_subst_expr(*expr)),
ty: self.apply_subst(&ty),
},
TypedExprKind::Call { callee, args } => TypedExprKind::Call {
callee: Box::new(self.apply_subst_expr(*callee)),
args: args.into_iter().map(|a| self.apply_subst_expr(a)).collect(),
},
};
TypedExpr { kind, ty, span }
src/frontend/token.rs
+2
View File
@@ -57,6 +57,7 @@ pub enum TokenKind {
// Keywords
Fn,
Foreign,
If,
As,
Else,
@@ -121,6 +122,7 @@ impl Display for TokenKind {
TokenKind::BooleanLit => "a boolean",
TokenKind::FloatLit => "a float",
TokenKind::Fn => "`fn`",
TokenKind::Foreign => "`foreign`",
TokenKind::As => "`as`",
TokenKind::If => "`if`",
TokenKind::Else => "`else`",
src/middle/builder.rs
+45 -1
View File
@@ -10,6 +10,7 @@ pub struct MirBuilder;
impl MirBuilder {
/// Builds a `MirModule` from a `TypedModule`.
pub fn build(module: &TypedModule) -> MirModule {
let mut extern_functions = Vec::new();
let mut functions = Vec::new();
for decl in &module.decls {
@@ -53,10 +54,25 @@ impl MirBuilder {
functions.push(builder.finish());
}
TypedDeclKind::ForeignFunction {
name,
params,
return_type,
..
} => {
extern_functions.push(MirExternFunction {
name: name.clone(),
params: params.iter().map(|(_, ty)| ty.clone()).collect(),
return_type: return_type.clone(),
});
}
}
}
MirModule { functions }
MirModule {
extern_functions,
functions,
}
}
}
@@ -399,6 +415,34 @@ impl FuncBuilder {
Operand::Copy(temp)
}
TypedExprKind::Call { callee, args } => {
let callee_name = match &callee.kind {
TypedExprKind::Identifier { name } => name.clone(),
_ => unimplemented!("indirect function calls are not yet supported"),
};
let mut arg_ops = Vec::new();
for arg in args {
arg_ops.push(self.lower_expr(arg));
}
let rval = Rvalue::Call(callee_name, arg_ops, expr.ty.clone());
if expr.ty == Ty::Unit {
self.emit_stmt(Statement {
kind: StatementKind::SideEffect(rval),
span: expr.span,
});
Operand::Constant(ConstantValue::Boolean(false)) // Dummy value for Unit assignments
} else {
let temp = self.new_temp(expr.ty.clone());
self.emit_stmt(Statement {
kind: StatementKind::Assign(temp, rval),
span: expr.span,
});
Operand::Copy(temp)
}
}
}
}
}
src/middle/dce.rs
+2
View File
@@ -126,6 +126,7 @@ mod test {
},
],
}],
extern_functions: vec![],
};
let warnings = eliminate_dead_code(&mut module);
@@ -180,6 +181,7 @@ mod test {
},
],
}],
extern_functions: vec![],
};
let warnings = eliminate_dead_code(&mut module);
src/middle/fold.rs
+17 -3
View File
@@ -19,8 +19,8 @@ fn optimize_function(func: &mut MirFunction) {
let mut known_constants = HashMap::new();
for stmt in &mut block.statements {
let StatementKind::Assign(local, rvalue) = &mut stmt.kind;
match &mut stmt.kind {
StatementKind::Assign(local, rvalue) => {
// Propagate any known constants downwards into the rvalue
propagate_rvalue(rvalue, &known_constants);
@@ -34,6 +34,11 @@ fn optimize_function(func: &mut MirFunction) {
known_constants.remove(local);
}
}
StatementKind::SideEffect(rvalue) => {
propagate_rvalue(rvalue, &known_constants);
}
}
}
// Propagate constants into the terminator
match &mut block.terminator.kind {
@@ -76,6 +81,11 @@ fn propagate_rvalue(rvalue: &mut Rvalue, known_constants: &HashMap<LocalId, Cons
propagate_operand(rhs, known_constants);
}
Rvalue::Cast(_, op) => propagate_operand(op, known_constants),
Rvalue::Call(_, args, _) => {
for arg in args {
propagate_operand(arg, known_constants);
}
}
}
}
@@ -295,6 +305,7 @@ mod test {
let mut module = MirModule {
functions: vec![func],
extern_functions: vec![],
};
fold_constants(&mut module);
@@ -302,7 +313,9 @@ mod test {
let block = &module.functions[0].blocks[0];
// The third statement (LocalId(2) = ...) should be folded to 15
let StatementKind::Assign(_, rvalue) = &block.statements[2].kind;
let StatementKind::Assign(_, rvalue) = &block.statements[2].kind else {
panic!();
};
assert!(matches!(
rvalue,
Rvalue::Use(Operand::Constant(ConstantValue::Integer(15, Ty::I32)))
@@ -340,6 +353,7 @@ mod test {
let mut module = MirModule {
functions: vec![func],
extern_functions: vec![],
};
fold_constants(&mut module);
src/middle/mir.rs
+11
View File
@@ -12,9 +12,17 @@ pub struct LocalId(pub usize);
#[derive(Debug)]
pub struct MirModule {
pub extern_functions: Vec<MirExternFunction>,
pub functions: Vec<MirFunction>,
}
#[derive(Debug)]
pub struct MirExternFunction {
pub name: String,
pub params: Vec<Ty>,
pub return_type: Ty,
}
#[derive(Debug)]
pub struct MirFunction {
pub name: String,
@@ -52,6 +60,8 @@ pub struct Statement {
pub enum StatementKind {
/// Assigns the result of an Rvalue to a local variable or temporary.
Assign(LocalId, Rvalue),
/// Executes an Rvalue strictly for its side effects (e.g. FFI calling `Unit` functions)
SideEffect(Rvalue),
}
/// Operations that produce a value.
@@ -61,6 +71,7 @@ pub enum Rvalue {
UnaryOp(UnaryOp, Operand),
BinaryOp(BinaryOp, Operand, Operand),
Cast(Ty, Operand),
Call(String, Vec<Operand>, Ty),
}
/// An atomic value used as inputs to instructions.
tests/ffi_bindings.test
+17
View File
@@ -0,0 +1,17 @@
[code]
foreign fn putchar(c: i32) -> i32;
fn main() -> i32 {
putchar(72); // 'H'
putchar(105); // 'i'
putchar(33); // '!'
putchar(10); // '\n'
return 0;
}
[expected_return_code]
0
[expected_output]
Hi!