Initial commit

1 files changed, 282 insertions, 0 deletions

diff --git a/src/codegen/llvm.rs b/src/codegen/llvm.rs
new file mode 100644
index 000000000000..ff92c3373176
--- /dev/null
+++ b/src/codegen/llvm.rs
@@ -0,0 +1,282 @@
+use std::path::Path;
+use std::result;
+
+use inkwell::basic_block::BasicBlock;
+use inkwell::builder::Builder;
+pub use inkwell::context::Context;
+use inkwell::module::Module;
+use inkwell::support::LLVMString;
+use inkwell::types::FunctionType;
+use inkwell::values::{BasicValueEnum, FunctionValue};
+use inkwell::IntPredicate;
+use thiserror::Error;
+
+use crate::ast::{BinaryOperator, Decl, Expr, Fun, Ident, Literal, UnaryOperator};
+use crate::common::env::Env;
+
+#[derive(Debug, PartialEq, Eq, Error)]
+pub enum Error {
+    #[error("Undefined variable {0}")]
+    UndefinedVariable(Ident<'static>),
+
+    #[error("LLVM Error: {0}")]
+    LLVMError(String),
+}
+
+impl From<LLVMString> for Error {
+    fn from(s: LLVMString) -> Self {
+        Self::LLVMError(s.to_string())
+    }
+}
+
+pub type Result<T> = result::Result<T, Error>;
+
+pub struct Codegen<'ctx, 'ast> {
+    context: &'ctx Context,
+    pub module: Module<'ctx>,
+    builder: Builder<'ctx>,
+    env: Env<'ast, BasicValueEnum<'ctx>>,
+    function: Option<FunctionValue<'ctx>>,
+}
+
+impl<'ctx, 'ast> Codegen<'ctx, 'ast> {
+    pub fn new(context: &'ctx Context, module_name: &str) -> Self {
+        let module = context.create_module(module_name);
+        let builder = context.create_builder();
+        Self {
+            context,
+            module,
+            builder,
+            env: Default::default(),
+            function: None,
+        }
+    }
+
+    pub fn new_function<'a>(
+        &'a mut self,
+        name: &str,
+        ty: FunctionType<'ctx>,
+    ) -> &'a FunctionValue<'ctx> {
+        self.function = Some(self.module.add_function(name, ty, None));
+        let basic_block = self.append_basic_block("entry");
+        self.builder.position_at_end(basic_block);
+        self.function.as_ref().unwrap()
+    }
+
+    pub fn finish_function(&self, res: &BasicValueEnum<'ctx>) {
+        self.builder.build_return(Some(res));
+    }
+
+    pub fn append_basic_block(&self, name: &str) -> BasicBlock<'ctx> {
+        self.context
+            .append_basic_block(self.function.unwrap(), name)
+    }
+
+    pub fn codegen_expr(&mut self, expr: &'ast Expr<'ast>) -> Result<BasicValueEnum<'ctx>> {
+        match expr {
+            Expr::Ident(id) => self
+                .env
+                .resolve(id)
+                .cloned()
+                .ok_or_else(|| Error::UndefinedVariable(id.to_owned())),
+            Expr::Literal(Literal::Int(i)) => {
+                let ty = self.context.i64_type();
+                Ok(BasicValueEnum::IntValue(ty.const_int(*i, false)))
+            }
+            Expr::UnaryOp { op, rhs } => {
+                let rhs = self.codegen_expr(rhs)?;
+                match op {
+                    UnaryOperator::Not => unimplemented!(),
+                    UnaryOperator::Neg => Ok(BasicValueEnum::IntValue(
+                        self.builder.build_int_neg(rhs.into_int_value(), "neg"),
+                    )),
+                }
+            }
+            Expr::BinaryOp { lhs, op, rhs } => {
+                let lhs = self.codegen_expr(lhs)?;
+                let rhs = self.codegen_expr(rhs)?;
+                match op {
+                    BinaryOperator::Add => {
+                        Ok(BasicValueEnum::IntValue(self.builder.build_int_add(
+                            lhs.into_int_value(),
+                            rhs.into_int_value(),
+                            "add",
+                        )))
+                    }
+                    BinaryOperator::Sub => {
+                        Ok(BasicValueEnum::IntValue(self.builder.build_int_sub(
+                            lhs.into_int_value(),
+                            rhs.into_int_value(),
+                            "add",
+                        )))
+                    }
+                    BinaryOperator::Mul => {
+                        Ok(BasicValueEnum::IntValue(self.builder.build_int_sub(
+                            lhs.into_int_value(),
+                            rhs.into_int_value(),
+                            "add",
+                        )))
+                    }
+                    BinaryOperator::Div => {
+                        Ok(BasicValueEnum::IntValue(self.builder.build_int_signed_div(
+                            lhs.into_int_value(),
+                            rhs.into_int_value(),
+                            "add",
+                        )))
+                    }
+                    BinaryOperator::Pow => unimplemented!(),
+                    BinaryOperator::Equ => {
+                        Ok(BasicValueEnum::IntValue(self.builder.build_int_compare(
+                            IntPredicate::EQ,
+                            lhs.into_int_value(),
+                            rhs.into_int_value(),
+                            "eq",
+                        )))
+                    }
+                    BinaryOperator::Neq => todo!(),
+                }
+            }
+            Expr::Let { bindings, body } => {
+                self.env.push();
+                for (id, val) in bindings {
+                    let val = self.codegen_expr(val)?;
+                    self.env.set(id, val);
+                }
+                let res = self.codegen_expr(body);
+                self.env.pop();
+                res
+            }
+            Expr::If {
+                condition,
+                then,
+                else_,
+            } => {
+                let then_block = self.append_basic_block("then");
+                let else_block = self.append_basic_block("else");
+                let join_block = self.append_basic_block("join");
+                let condition = self.codegen_expr(condition)?;
+                self.builder.build_conditional_branch(
+                    condition.into_int_value(),
+                    then_block,
+                    else_block,
+                );
+                self.builder.position_at_end(then_block);
+                let then_res = self.codegen_expr(then)?;
+                self.builder.build_unconditional_branch(join_block);
+
+                self.builder.position_at_end(else_block);
+                let else_res = self.codegen_expr(else_)?;
+                self.builder.build_unconditional_branch(join_block);
+
+                self.builder.position_at_end(join_block);
+                let phi = self.builder.build_phi(self.context.i64_type(), "join");
+                phi.add_incoming(&[(&then_res, then_block), (&else_res, else_block)]);
+                Ok(phi.as_basic_value())
+            }
+        }
+    }
+
+    pub fn codegen_decl(&mut self, decl: &'ast Decl<'ast>) -> Result<()> {
+        match decl {
+            Decl::Fun(Fun { name, args, body }) => {
+                let i64_type = self.context.i64_type();
+                self.new_function(
+                    name.into(),
+                    i64_type.fn_type(
+                        args.iter()
+                            .map(|_| i64_type.into())
+                            .collect::<Vec<_>>()
+                            .as_slice(),
+                        false,
+                    ),
+                );
+                self.env.push();
+                for (i, arg) in args.iter().enumerate() {
+                    self.env
+                        .set(arg, self.function.unwrap().get_nth_param(i as u32).unwrap());
+                }
+                let res = self.codegen_expr(body)?;
+                self.env.pop();
+                self.finish_function(&res);
+                Ok(())
+            }
+        }
+    }
+
+    pub fn codegen_main(&mut self, expr: &'ast Expr<'ast>) -> Result<()> {
+        self.new_function("main", self.context.i64_type().fn_type(&[], false));
+        let res = self.codegen_expr(expr)?;
+        self.finish_function(&res);
+        Ok(())
+    }
+
+    pub fn print_to_file<P>(&self, path: P) -> Result<()>
+    where
+        P: AsRef<Path>,
+    {
+        Ok(self.module.print_to_file(path)?)
+    }
+
+    pub fn binary_to_file<P>(&self, path: P) -> Result<()>
+    where
+        P: AsRef<Path>,
+    {
+        if self.module.write_bitcode_to_path(path.as_ref()) {
+            Ok(())
+        } else {
+            Err(Error::LLVMError(
+                "Error writing bitcode to output path".to_owned(),
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use inkwell::execution_engine::JitFunction;
+    use inkwell::OptimizationLevel;
+
+    use super::*;
+
+    fn jit_eval<T>(expr: &str) -> anyhow::Result<T> {
+        let expr = crate::parser::expr(expr).unwrap().1;
+
+        let context = Context::create();
+        let mut codegen = Codegen::new(&context, "test");
+        let execution_engine = codegen
+            .module
+            .create_jit_execution_engine(OptimizationLevel::None)
+            .unwrap();
+
+        codegen.new_function("test", context.i64_type().fn_type(&[], false));
+        let res = codegen.codegen_expr(&expr)?;
+        codegen.finish_function(&res);
+
+        unsafe {
+            let fun: JitFunction<unsafe extern "C" fn() -> T> =
+                execution_engine.get_function("test")?;
+            Ok(fun.call())
+        }
+    }
+
+    #[test]
+    fn add_literals() {
+        assert_eq!(jit_eval::<i64>("1 + 2").unwrap(), 3);
+    }
+
+    #[test]
+    fn variable_shadowing() {
+        assert_eq!(
+            jit_eval::<i64>("let x = 1 in (let x = 2 in x) + x").unwrap(),
+            3
+        );
+    }
+
+    #[test]
+    fn eq() {
+        assert_eq!(
+            jit_eval::<i64>("let x = 1 in if x == 1 then 2 else 4").unwrap(),
+            2
+        );
+    }
+}