Add initial tail-call optimization

1 files changed, 15 insertions, 7 deletions

diff --git a/src/bytecode/vm.h b/src/bytecode/vm.h
index 98c94fa..6c44fc6 100755
--- a/src/bytecode/vm.h
+++ b/src/bytecode/vm.h
@@ -261,13 +261,21 @@ vm_interpret(VM *vm) {
             } break;
             case OP_CALL: {
                 Object proc = array_pop(vm->stack);
-                CallFrame new_frame = (CallFrame){
-                    .chunk = proc.chunk,
-                    .rp = vm->pc,
-                    .stack_offset = array_size(vm->stack) - array_size(proc.chunk->params),
-                };
-                array_push(vm->frames, new_frame);
-                frame = &vm->frames[array_size(vm->frames) - 1];
+
+                // Tail-call optimization.
+                if (proc.chunk != frame->chunk || *vm->pc != OP_RETURN) {
+                    CallFrame new_frame = (CallFrame){
+                        .chunk = proc.chunk,
+                        .rp = vm->pc,
+                        .stack_offset = array_size(vm->stack) - array_size(proc.chunk->params),
+                    };
+                    array_push(vm->frames, new_frame);
+                    frame = &vm->frames[array_size(vm->frames) - 1];
+                } else {
+                    // TODO: restore all parameters.
+                    Object a = array_pop(vm->stack);
+                    vm->stack[frame->stack_offset] = a;
+                }
                 vm->pc = frame->chunk->code;
             } break;
             case OP_RETURN: {