Add Invoke op to optimize method calls; require explicit this

Author: mustafaquraish

compiler/bytecode.oc

@@ -38,6 +38,7 @@ enum OpCode {
     SetMember
     GetMember
     Method
+    Invoke
 }
 
 struct DebugLocRun {
@@ -173,7 +174,7 @@ def Chunk::disassemble_inst(&this, off: u32, found_chunks: &Vector<&Chunk> = nul
         LessThan => println("LessThan")
         GreaterThan => println("GreaterThan")
         Equal => println("Equal")
-        SetMember | GetMember | Class | GetGlobal | SetGlobal | Method  => {
+        SetMember | GetMember | Class | GetGlobal | SetGlobal | Method | Invoke  => {
             let name = .read_literal(&off).as_obj() as &String
             println(f"{op} {name.data}")
         }

compiler/compiler.oc

@@ -267,15 +267,34 @@ def Compiler::compile_expression(&this, node: &AST) {
         Identifier => .compile_variable(node.u.ident.name, node.span)
         Call => {
             let callee = node.u.call.callee
+            let args = node.u.call.args
 
-            .compile_expression(callee)
+            match callee.type {
+                // Special case for `a.b()`, which generates
+                //      GET a, ... INVOKE b
+                // instead of
+                //      GET a, GET_MEMBER b ... CALL
+                Member => {
+                    let member = callee.u.member
+                    .compile_expression(member.lhs)
+
+                    for arg in node.u.call.args.iter() {
+                        .compile_expression(arg.expr)
+                    }
 
-            let args = node.u.call.args
-            for arg in args.iter() {
-                .compile_expression(arg.expr)
+                    let name = .make_str(member.rhs_name)
+                    .chunk.push_with_literal(.vm, Invoke, name, node.span)
+                    .chunk.push_u8(args.size as u8, node.span)
+                }
+                else => {
+                    .compile_expression(callee)
+                    for arg in node.u.call.args.iter() {
+                        .compile_expression(arg.expr)
+                    }
+                    .chunk.push_with_arg_u8(Call, args.size as u8, node.span)
+                }
             }
 
-            .chunk.push_with_arg_u8(Call, args.size as u8, node.span)
         }
         Member => {
             let member = node.u.member
@@ -499,6 +518,7 @@ def Compiler::compile_statement(&this, node: &AST) {
         }
         // TODO: Disallow return in constructor
         // TODO: Disallow return in global scope, maybe?
+        // TODO: If ArrowReturn in constructor, treat as statement
         Return | ArrowReturn => {
             if node.u.child? {
                 .compile_expression(node.u.child)

compiler/parser.oc

@@ -1197,6 +1197,7 @@ def Parser::parse_function(&this, type: FunctionType): &AST {
     let start = .consume(Def)
 
     let name = .consume(Identifier)
+    let expect_this_arg = (type == Method)
 
     if type == Method and name.text == "init" {
         type = Constructor
@@ -1210,18 +1211,27 @@ def Parser::parse_function(&this, type: FunctionType): &AST {
     .add_doc_comment(func.sym, start)
 
     .consume(OpenParen)
+    let found_this_arg = false
     while not .token_is(CloseParen) {
         let var_name = .consume(Identifier)
-
-        let var = Variable::new()
-        var.sym = Symbol::from_variable(var_name.text, var, var_name.span)
-        func.params.push(var)
-        .add_doc_comment(var.sym, var_name)
+        if func.params.size == 0 and var_name.text == "this" {
+            // Don't actually need to add `this` to the params list, since
+            // we special-case this when binding methods.
+            found_this_arg = true
+        } else {
+            let var = Variable::new()
+            var.sym = Symbol::from_variable(var_name.text, var, var_name.span)
+            func.params.push(var)
+            .add_doc_comment(var.sym, var_name)
+        }
 
         if not .token_is(CloseParen) {
             .consume(Comma)
         }
     }
+    if expect_this_arg and not found_this_arg {
+        .error(Error::new(func.sym.span, "Method must have a `this` as first argument"))
+    }
     let end_span = .consume(CloseParen).span
 
     .cur_func = func

compiler/vm/mod.oc

@@ -166,7 +166,12 @@ def VM::add(&this, a: Value, b: Value): Value => if {
         //        allocate the new one (which can trigger a GC collection)
         .tmp.push(a)
         .tmp.push(b)
-        let res = .take_string(`{a_str.data}{b_str.data}`, a_str.len + b_str.len)
+        let s = mem::alloc<char>(a_str.len + b_str.len + 1)
+        import std::libc::memcpy
+        memcpy(s            , a_str.data, a_str.len)
+        memcpy(s + a_str.len, b_str.data, b_str.len)
+        s[a_str.len + b_str.len] = '\0'
+        let res = .take_string(s, a_str.len + b_str.len)
         .tmp.pop() // b
         .tmp.pop() // a
         yield res
@@ -407,7 +412,7 @@ def VM::bind_method(&this, instance: Value, func: &Function) {
     .stack.push(Value::Object(&bound.obj))
 }
 
-def VM::call(&this, arity: u32, func: &Function) {
+def VM::call_function(&this, arity: u32, func: &Function) {
     if func.code.arity as u32 != arity {
         .error(f"Function {func.code.name.data} expected {func.code.arity} arguments, got {arity}")
     }
@@ -417,13 +422,58 @@ def VM::call(&this, arity: u32, func: &Function) {
     .tmp.pop()
 }
 
+def VM::call_value(&this, arity: u32, val: Value) {
+    if not val.is_obj() {
+        .error(f"Can't call object of type {val.type_str()}")
+    }
+
+    match val.as_obj().type {
+        Function => .call_function(arity, val.as_function())
+        NativeFunction => {
+            let func = val.as_native_function()
+            let res = func.func(this, arity, &.stack.data[.stack.size - arity])
+            .stack.size -= arity as u32 + 1  // Pop the arguments and the function
+            .stack.push(res)
+        }
+        Class => {
+            let class = val.as_class()
+            let instance = gc::allocate_object<Instance>(ObjectType::Instance, this)
+            let val = Value::Object(&instance.obj)
+            instance.fields = null
+
+            // instance.init allocates memory, so we need to push this on the stack
+            // so the GC can find it if we collect
+            .stack.push(val)
+            instance.init(class)
+            .stack.pop()
+
+            .stack.data[.stack.size - arity - 1] = val
+
+            let init_it = class.methods.get_item(.init_string)
+            if init_it? {
+                .call_function(arity, init_it.value)
+
+            } else if arity != 0 {
+                .error(f"Can't provide arguments to class without init()")
+            }
+        }
+        Method => {
+            let method = val.as_method()
+            .stack.data[.stack.size - arity - 1] = method.this_val
+            .call_function(arity, method.func)
+        }
+        FunctionCode => .error("Function should have been a func")
+        else => .error(f"Can't call object of type {val.type_str()}")
+    }
+}
+
 def VM::main_loop(&this): i32 {
     while true {
         // FIXME: For `tests/native_fn.td`, having this line here
         //        causes perf to go from 1.2s -> 1.6s, _even if_
         //        the debug == false. Saving it into a local variable
         //        from the global one doesn't help either.
-        if debug then .debug_dump_inst(print_stack: true)
+        // if debug then .debug_dump_inst(print_stack: true)
 
         .cur_inst_ip = .ip
         let op = .read_u8() as OpCode
@@ -518,49 +568,7 @@ def VM::main_loop(&this): i32 {
             Call => {
                 let arity = .read_u8() as u32
                 let val = .stack.back(arity as u32)
-
-                if not val.is_obj() {
-                    .error(f"Can't call object of type {val.type_str()}")
-                }
-
-                match val.as_obj().type {
-                    Function => .call(arity, val.as_function())
-                    NativeFunction => {
-                        let func = val.as_native_function()
-                        let res = func.func(this, arity, &.stack.data[.stack.size - arity])
-                        .stack.size -= arity as u32 + 1  // Pop the arguments and the function
-                        .stack.push(res)
-                    }
-                    Class => {
-                        let class = val.as_class()
-                        let instance = gc::allocate_object<Instance>(ObjectType::Instance, this)
-                        let val = Value::Object(&instance.obj)
-                        instance.fields = null
-
-                        // instance.init allocates memory, so we need to push this on the stack
-                        // so the GC can find it if we collect
-                        .stack.push(val)
-                        instance.init(class)
-                        .stack.pop()
-
-                        .stack.data[.stack.size - arity - 1] = val
-
-                        let init_it = class.methods.get_item(.init_string)
-                        if init_it? {
-                            .call(arity, init_it.value)
-
-                        } else if arity != 0 {
-                            .error(f"Can't provide arguments to class without init()")
-                        }
-                    }
-                    Method => {
-                        let method = val.as_method()
-                        .stack.data[.stack.size - arity - 1] = method.this_val
-                        .call(arity, method.func)
-                    }
-                    FunctionCode => .error("Function should have been a func")
-                    else => .error(f"Can't call object of type {val.type_str()}")
-                }
+                .call_value(arity, val)
             }
             GetGlobal => {
                 let name = .read_literal().as_string()
@@ -617,6 +625,31 @@ def VM::main_loop(&this): i32 {
 
                 .error(f"Member {name.data} not found")
             }
+            Invoke => {
+                let name = .read_literal().as_string()
+                let arity = .read_u8() as u32
+
+                let obj = .stack.back(arity)
+                if not obj.is_instance() {
+                    .error(f"Can't access a field/member on object of type {obj.type_str()}")
+                }
+                let instance = obj.as_instance()
+                let func = instance.class.methods.get(name, null)
+                if func? {
+                    // NOTE: the instance is already on the stack in the
+                    //       correct position to bind `this`, so we don't
+                    //       need to do anything here.
+                    .call_function(arity, func)
+
+                } else {
+                    let it = instance.fields.get_item(name)
+                    if not it? {
+                        .error(f"Could not find field/method with name {name}")
+                    }
+                    .call_value(arity, it.value)
+                }
+
+            }
             Null => .stack.push(Value::Null())
             True => .stack.push(Value::True())
             False => .stack.push(Value::False())

tests/class_init.td

@@ -1,15 +1,15 @@
 /// out: Person: John 30 JohnJohnJohn
 
 class Person {
-    def init(name, age) {
+    def init(this, name, age) {
         .name = name
         .age = age
     }
 
-    def print() {
+    def print(this) {
         print("Person: " + .name, .age)
     }
-    def bar() => .name + .name + .name
+    def bar(this) => .name + .name + .name
 }
 
 

tests/class_methods.td

@@ -1,8 +1,8 @@
 /// out: <instance Foo> 5 8
 
 class Foo {
-    def bar() => .x = 5
-    def test(a, b) => .x + a + b
+    def bar(this) => .x = 5
+    def test(this, a, b) => .x + a + b
 }
 
 let f = Foo()

tests/field_func_call.td

@@ -0,0 +1,17 @@
+/// out: not a method
+
+// Makes sure we haven't broken this case with the
+// INVOKE opcode.
+
+class Oops {
+    def init(this) {
+        def f() {
+            print("not a method")
+        }
+
+        this.field = f
+    }
+}
+
+let oops = Oops()
+oops.field()

tests/method_bench.td

@@ -0,0 +1,22 @@
+/// out: OK
+
+class Foo {
+    def init(this) {
+        .name = "foo"
+    }
+    def bar(this) => .name + "hello"
+}
+
+let foo = Foo()
+
+let start = clock()
+
+for let i = 0; i < 10; i = i + 1 {
+    for let i = 0; i < 10000; i = i + 1 {
+        foo.bar()
+    }
+}
+
+let end = clock()
+print("Took", end-start, "seconds")
+print("OK")