tco

parse.cm

@@ -1425,7 +1425,9 @@ var parse = function(tokens, src, filename, tokenizer) {
       vars: [],
       in_loop: opts.in_loop == true,
       function_nr: fn_nr,
-      is_function_scope: opts.is_func == true
+      is_function_scope: opts.is_func == true,
+      func_node: null,
+      has_inner_func: false
     }
   }
 
@@ -1478,6 +1480,15 @@ var parse = function(tokens, src, filename, tokenizer) {
     return false
   }
 
+  var sem_find_func_scope = function(scope) {
+    var s = scope
+    while (s != null) {
+      if (s.is_function_scope) return s
+      s = s.parent
+    }
+    return null
+  }
+
   var sem_add_intrinsic = function(name) {
     if (find(intrinsics, name) == null) push(intrinsics, name)
   }
@@ -1635,6 +1646,7 @@ var parse = function(tokens, src, filename, tokenizer) {
     var pname = null
     var def_val = null
     var sr = null
+    var enclosing = null
 
     if (_assign_kinds[kind] == true) {
       sem_check_assign_target(scope, expr.left)
@@ -1736,9 +1748,12 @@ var parse = function(tokens, src, filename, tokenizer) {
     }
 
     if (kind == "function") {
+      enclosing = sem_find_func_scope(scope)
+      if (enclosing != null) enclosing.has_inner_func = true
       fn_nr_val = expr.function_nr
       if (fn_nr_val == null) fn_nr_val = scope.function_nr
       fn_scope = make_scope(scope, fn_nr_val, {is_func: true})
+      fn_scope.func_node = expr
       expr.outer = scope.function_nr
       i = 0
       while (i < length(expr.list)) {
@@ -1819,6 +1834,8 @@ var parse = function(tokens, src, filename, tokenizer) {
     var pname = null
     var def_val = null
     var sr = null
+    var enclosing = null
+    var func_scope = null
     var tt = null
 
     if (kind == "var_list") {
@@ -1941,7 +1958,26 @@ var parse = function(tokens, src, filename, tokenizer) {
       return null
     }
 
-    if (kind == "return" || kind == "go") {
+    if (kind == "go") {
+      sem_check_expr(scope, stmt.expression)
+      if (stmt.expression == null || stmt.expression.kind != "(") {
+        sem_error(stmt, "'go' must be followed by a function call")
+      } else {
+        func_scope = sem_find_func_scope(scope)
+        if (func_scope != null && func_scope.func_node != null) {
+          if (func_scope.func_node.disruption != null) {
+            sem_error(stmt, "cannot use 'go' in a function with a disruption clause")
+          }
+          if (func_scope.has_inner_func) {
+            sem_error(stmt, "cannot use 'go' in a function that defines inner functions")
+          }
+        }
+        stmt.tail = true
+      }
+      return null
+    }
+
+    if (kind == "return") {
       sem_check_expr(scope, stmt.expression)
       if (stmt.expression != null && stmt.expression.kind == "(") {
         stmt.tail = true
@@ -1982,11 +2018,14 @@ var parse = function(tokens, src, filename, tokenizer) {
     }
 
     if (kind == "function") {
+      enclosing = sem_find_func_scope(scope)
+      if (enclosing != null) enclosing.has_inner_func = true
       name = stmt.name
       if (name != null) sem_add_var(scope, name, {make: "function", fn_nr: scope.function_nr})
       fn_nr_val = stmt.function_nr
       if (fn_nr_val == null) fn_nr_val = scope.function_nr
       fn_scope = make_scope(scope, fn_nr_val, {is_func: true})
+      fn_scope.func_node = stmt
       stmt.outer = scope.function_nr
       i = 0
       while (i < length(stmt.list)) {

qbe_emit.cm

@@ -650,7 +650,8 @@ var qbe_emit = function(ir, qbe) {
         continue
       }
       if (op == "goinvoke") {
-        emit(`  call $cell_rt_goinvoke(l %ctx, l ${s(a1)})`)
+        emit(`  %_goret =l call $cell_rt_goinvoke(l %ctx, l ${s(a1)})`)
+        emit(`  ret %_goret`)
         continue
       }
 

source/mach.c

@@ -1702,17 +1702,68 @@ JSValue JS_CallRegisterVM(JSContext *ctx, JSCodeRegister *code,
       break;
     }
     case MACH_GOINVOKE: {
-      /* Async invoke: call and discard result */
+      /* Tail call: replace current frame with callee */
       JSFrameRegister *fr = (JSFrameRegister *)JS_VALUE_GET_PTR(frame->slots[a]);
       int nr = (int)objhdr_cap56(fr->hdr);
       int c_argc = (nr >= 2) ? nr - 2 : 0;
-      ctx->reg_current_frame = frame_ref.val;
-      ctx->current_register_pc = pc > 0 ? pc - 1 : 0;
-      JSValue ret = JS_Call(ctx, fr->function, fr->slots[0],
-                            c_argc, &fr->slots[1]);
-      frame = (JSFrameRegister *)JS_VALUE_GET_PTR(frame_ref.val);
-      ctx->reg_current_frame = JS_NULL;
-      if (JS_IsException(ret)) goto disrupt;
+      JSValue fn_val = fr->function;
+      JSFunction *fn = JS_VALUE_GET_FUNCTION(fn_val);
+
+      if (fn->kind == JS_FUNC_KIND_REGISTER) {
+        /* Register function: tail call by replacing current frame */
+        JSCodeRegister *fn_code = fn->u.reg.code;
+        JSFrameRegister *new_frame = alloc_frame_register(ctx, fn_code->nr_slots);
+        if (!new_frame) {
+          frame = (JSFrameRegister *)JS_VALUE_GET_PTR(frame_ref.val);
+          goto disrupt;
+        }
+        frame = (JSFrameRegister *)JS_VALUE_GET_PTR(frame_ref.val);
+        fr = (JSFrameRegister *)JS_VALUE_GET_PTR(frame->slots[a]);
+        fn_val = fr->function;
+        fn = JS_VALUE_GET_FUNCTION(fn_val);
+        fn_code = fn->u.reg.code;
+        new_frame->function = fn_val;
+        /* Copy this + args from call frame to new frame */
+        int copy_count = (c_argc < fn_code->arity) ? c_argc : fn_code->arity;
+        new_frame->slots[0] = fr->slots[0]; /* this */
+        for (int i = 0; i < copy_count; i++)
+          new_frame->slots[1 + i] = fr->slots[1 + i];
+        /* Tail call: callee returns to OUR caller, not to us */
+        new_frame->caller = frame->caller;
+        frame->caller = JS_NULL; /* detach current frame */
+        /* Switch to callee */
+        frame = new_frame;
+        frame_ref.val = JS_MKPTR(frame);
+        code = fn_code;
+        env = fn->u.reg.env_record;
+        pc = code->entry_point;
+      } else {
+        /* C/bytecode function: call it, then return result to our caller */
+        ctx->reg_current_frame = frame_ref.val;
+        ctx->current_register_pc = pc > 0 ? pc - 1 : 0;
+        JSValue ret;
+        if (fn->kind == JS_FUNC_KIND_C)
+          ret = js_call_c_function(ctx, fn_val, fr->slots[0], c_argc, &fr->slots[1]);
+        else
+          ret = JS_CallInternal(ctx, fn_val, fr->slots[0], c_argc, &fr->slots[1], 0);
+        frame = (JSFrameRegister *)JS_VALUE_GET_PTR(frame_ref.val);
+        ctx->reg_current_frame = JS_NULL;
+        if (JS_IsException(ret)) goto disrupt;
+        /* Tail-return: act like MACH_RETURN with the result */
+        result = ret;
+        if (JS_IsNull(frame->caller)) goto done;
+        JSFrameRegister *caller = (JSFrameRegister *)JS_VALUE_GET_PTR(frame->caller);
+        frame->caller = JS_NULL;
+        frame = caller;
+        frame_ref.val = JS_MKPTR(frame);
+        int ret_info = JS_VALUE_GET_INT(frame->address);
+        JSFunction *ret_fn = JS_VALUE_GET_FUNCTION(frame->function);
+        code = ret_fn->u.reg.code;
+        env = ret_fn->u.reg.env_record;
+        pc = ret_info >> 16;
+        int ret_slot = ret_info & 0xFFFF;
+        if (ret_slot != 0xFFFF) frame->slots[ret_slot] = ret;
+      }
       break;
     }
 

source/qbe_helpers.c

@@ -351,8 +351,8 @@ JSValue cell_rt_goframe(JSContext *ctx, JSValue fn, int64_t nargs) {
   return cell_rt_frame(ctx, fn, nargs);
 }
 
-void cell_rt_goinvoke(JSContext *ctx, JSValue frame_val) {
-  cell_rt_invoke(ctx, frame_val);
+JSValue cell_rt_goinvoke(JSContext *ctx, JSValue frame_val) {
+  return cell_rt_invoke(ctx, frame_val);
 }
 
 /* --- Array push/pop --- */