feat: if expressions code generation

crates/mun_codegen/src/ir/function.rs

@@ -192,6 +192,11 @@ impl<'a, 'b, D: IrDatabase> BodyIrGenerator<'a, 'b, D> {
                 ref callee,
                 ref args,
             } => self.gen_call(*callee, &args).try_as_basic_value().left(),
+            Expr::If {
+                condition,
+                then_branch,
+                else_branch,
+            } => self.gen_if(expr, *condition, *then_branch, *else_branch),
             _ => unreachable!("unimplemented expr type"),
         };
 
@@ -365,8 +370,6 @@ impl<'a, 'b, D: IrDatabase> BodyIrGenerator<'a, 'b, D> {
             BinaryOp::ArithOp(ArithOp::Multiply) => {
                 self.builder.build_int_mul(lhs, rhs, "mul").into()
             }
-            //                BinaryOp::Remainder => Some(self.gen_remainder(lhs, rhs)),
-            //                BinaryOp::Power =>,
             //                BinaryOp::Assign,
             //                BinaryOp::AddAssign,
             //                BinaryOp::SubtractAssign,
@@ -436,6 +439,75 @@ impl<'a, 'b, D: IrDatabase> BodyIrGenerator<'a, 'b, D> {
                 .build_call(*llvm_function, &args, &function.name(self.db).to_string())
         }
     }
+
+    /// Generates IR for an if statement.
+    fn gen_if(
+        &mut self,
+        _expr: ExprId,
+        condition: ExprId,
+        then_branch: ExprId,
+        else_branch: Option<ExprId>,
+    ) -> Option<inkwell::values::BasicValueEnum> {
+        // Generate IR for the condition
+        let condition_ir = self
+            .gen_expr(condition)
+            .expect("condition must have a value")
+            .into_int_value();
+
+        // Generate the code blocks to branch to
+        let context = self.module.get_context();
+        let mut then_block = context.append_basic_block(&self.fn_value, "then");
+        let else_block_and_expr = match &else_branch {
+            Some(else_branch) => Some((
+                context.append_basic_block(&self.fn_value, "else"),
+                else_branch,
+            )),
+            None => None,
+        };
+        let merge_block = context.append_basic_block(&self.fn_value, "if_merge");
+
+        // Build the actual branching IR for the if statement
+        let else_block = else_block_and_expr
+            .as_ref()
+            .map(|e| &e.0)
+            .unwrap_or(&merge_block);
+        self.builder
+            .build_conditional_branch(condition_ir, &then_block, else_block);
+
+        // Fill the then block
+        self.builder.position_at_end(&then_block);
+        let then_block_ir = self.gen_expr(then_branch);
+        self.builder.build_unconditional_branch(&merge_block);
+        then_block = self.builder.get_insert_block().unwrap();
+
+        // Fill the else block, if it exists and get the result back
+        let else_ir_and_block = if let Some((else_block, else_branch)) = else_block_and_expr {
+            else_block.move_after(&then_block);
+            self.builder.position_at_end(&else_block);
+            let result_ir = self.gen_expr(*else_branch);
+            self.builder.build_unconditional_branch(&merge_block);
+            result_ir.map(|res| (res, self.builder.get_insert_block().unwrap()))
+        } else {
+            None
+        };
+
+        // Create merge block
+        merge_block.move_after(&self.builder.get_insert_block().unwrap());
+        self.builder.position_at_end(&merge_block);
+
+        // Construct phi block if a value was returned
+        if let Some(then_block_ir) = then_block_ir {
+            if let Some((else_block_ir, else_block)) = else_ir_and_block {
+                let phi = self.builder.build_phi(then_block_ir.get_type(), "iftmp");
+                phi.add_incoming(&[(&then_block_ir, &then_block), (&else_block_ir, &else_block)]);
+                Some(phi.as_basic_value())
+            } else {
+                Some(then_block_ir)
+            }
+        } else {
+            None
+        }
+    }
 }
 
 trait OptName {

crates/mun_codegen/src/snapshots/test__fibonacci.snap

@@ -0,0 +1,31 @@
+---
+source: crates/mun_codegen/src/test.rs
+expression: "fn fibonacci(n:int):int {\n    if n <= 1 {\n        n\n    } else {\n        fibonacci(n-1) + fibonacci(n-2)\n    }\n}"
+---
+; ModuleID = 'main.mun'
+source_filename = "main.mun"
+
+%DispatchTable = type { i64 (i64)* }
+
+@dispatchTable = global %DispatchTable { i64 (i64)* @fibonacci }
+
+define i64 @fibonacci(i64 %n) {
+body:
+  %lesseq = icmp sle i64 %n, 1
+  br i1 %lesseq, label %if_merge, label %else
+
+else:                                             ; preds = %body
+  %sub = sub i64 %n, 1
+  %fibonacci_ptr = load i64 (i64)*, i64 (i64)** getelementptr inbounds (%DispatchTable, %DispatchTable* @dispatchTable, i32 0, i32 0)
+  %fibonacci = call i64 %fibonacci_ptr(i64 %sub)
+  %sub1 = sub i64 %n, 2
+  %fibonacci_ptr2 = load i64 (i64)*, i64 (i64)** getelementptr inbounds (%DispatchTable, %DispatchTable* @dispatchTable, i32 0, i32 0)
+  %fibonacci3 = call i64 %fibonacci_ptr2(i64 %sub1)
+  %add = add i64 %fibonacci, %fibonacci3
+  br label %if_merge
+
+if_merge:                                         ; preds = %body, %else
+  %iftmp = phi i64 [ %add, %else ], [ %n, %body ]
+  ret i64 %iftmp
+}
+

crates/mun_codegen/src/snapshots/test__if_statement.snap

@@ -0,0 +1,16 @@
+---
+source: crates/mun_codegen/src/test.rs
+expression: "fn foo(a:int):int {\n    if a > 3 {\n        a+1\n    } else {\n        a-1\n    }\n}"
+---
+; ModuleID = 'main.mun'
+source_filename = "main.mun"
+
+define i64 @foo(i64 %a) {
+body:
+  %greater = icmp sgt i64 %a, 3
+  %add = add i64 %a, 1
+  %sub = sub i64 %a, 1
+  %iftmp = select i1 %greater, i64 %add, i64 %sub
+  ret i64 %iftmp
+}
+

crates/mun_codegen/src/test.rs

@@ -6,45 +6,6 @@ use mun_hir::SourceDatabase;
 use std::cell::RefCell;
 use std::sync::Arc;
 
-fn test_snapshot(text: &str) {
-    let text = text.trim().replace("\n    ", "\n");
-
-    let (db, file_id) = MockDatabase::with_single_file(&text);
-
-    let line_index: Arc<LineIndex> = db.line_index(file_id);
-    let messages = RefCell::new(Vec::new());
-    let mut sink = DiagnosticSink::new(|diag| {
-        let line_col = line_index.line_col(diag.highlight_range().start());
-        messages.borrow_mut().push(format!(
-            "error {}:{}: {}",
-            line_col.line + 1,
-            line_col.col + 1,
-            diag.message()
-        ));
-    });
-    if let Some(module) = Module::package_modules(&db)
-        .iter()
-        .find(|m| m.file_id() == file_id)
-    {
-        module.diagnostics(&db, &mut sink)
-    }
-    drop(sink);
-    let messages = messages.into_inner();
-
-    let name = if !messages.is_empty() {
-        messages.join("\n")
-    } else {
-        format!(
-            "{}",
-            db.module_ir(file_id)
-                .llvm_module
-                .print_to_string()
-                .to_string()
-        )
-    };
-    insta::assert_snapshot!(insta::_macro_support::AutoName, name, &text);
-}
-
 #[test]
 fn function() {
     test_snapshot(
@@ -185,3 +146,72 @@ fn equality_operands() {
     "#,
     );
 }
+
+#[test]
+fn if_statement() {
+    test_snapshot(
+        r#"
+    fn foo(a:int):int {
+        if a > 3 {
+            a+1
+        } else {
+            a-1
+        }
+    }
+    "#,
+    )
+}
+
+#[test]
+fn fibonacci() {
+    test_snapshot(
+        r#"
+    fn fibonacci(n:int):int {
+        if n <= 1 {
+            n
+        } else {
+            fibonacci(n-1) + fibonacci(n-2)
+        }
+    }
+    "#,
+    )
+}
+
+fn test_snapshot(text: &str) {
+    let text = text.trim().replace("\n    ", "\n");
+
+    let (db, file_id) = MockDatabase::with_single_file(&text);
+
+    let line_index: Arc<LineIndex> = db.line_index(file_id);
+    let messages = RefCell::new(Vec::new());
+    let mut sink = DiagnosticSink::new(|diag| {
+        let line_col = line_index.line_col(diag.highlight_range().start());
+        messages.borrow_mut().push(format!(
+            "error {}:{}: {}",
+            line_col.line + 1,
+            line_col.col + 1,
+            diag.message()
+        ));
+    });
+    if let Some(module) = Module::package_modules(&db)
+        .iter()
+        .find(|m| m.file_id() == file_id)
+    {
+        module.diagnostics(&db, &mut sink)
+    }
+    drop(sink);
+    let messages = messages.into_inner();
+
+    let name = if !messages.is_empty() {
+        messages.join("\n")
+    } else {
+        format!(
+            "{}",
+            db.module_ir(file_id)
+                .llvm_module
+                .print_to_string()
+                .to_string()
+        )
+    };
+    insta::assert_snapshot!(insta::_macro_support::AutoName, name, &text);
+}

crates/mun_runtime/src/test.rs

@@ -207,3 +207,31 @@ fn booleans() {
         false
     );
 }
+
+#[test]
+fn fibonacci() {
+    let compile_result = compile(
+        r#"
+    fn fibonacci(n:int):int {
+        if n <= 1 {
+            n
+        } else {
+            fibonacci(n-1) + fibonacci(n-2)
+        }
+    }
+    "#,
+    );
+    let mut runtime = compile_result.new_runtime();
+    assert_eq!(
+        MunRuntime::invoke_fn1::<i64, i64>(&mut runtime, "fibonacci", 5).unwrap(),
+        5
+    );
+    assert_eq!(
+        MunRuntime::invoke_fn1::<i64, i64>(&mut runtime, "fibonacci", 11).unwrap(),
+        89
+    );
+    assert_eq!(
+        MunRuntime::invoke_fn1::<i64, i64>(&mut runtime, "fibonacci", 16).unwrap(),
+        987
+    );
+}