Esempio n. 1
0
bool ast_passes_type(ast_t** astp, pass_opt_t* options)
{
  ast_t* ast = *astp;

  assert(ast_id(ast) == TK_ACTOR || ast_id(ast) == TK_CLASS ||
    ast_id(ast) == TK_STRUCT || ast_id(ast) == TK_PRIMITIVE ||
    ast_id(ast) == TK_TRAIT || ast_id(ast) == TK_INTERFACE);

  // We don't have the right frame stack for an entity, set up appropriate
  // frames
  ast_t* module = ast_parent(ast);
  ast_t* package = ast_parent(module);

  frame_push(&options->check, NULL);
  frame_push(&options->check, package);
  frame_push(&options->check, module);

  bool ok = ast_passes(astp, options, options->program_pass);

  frame_pop(&options->check);
  frame_pop(&options->check);
  frame_pop(&options->check);

  return ok;
}
Esempio n. 2
0
File: pass.c Progetto: ozra/ponyc
void pass_opt_init(pass_opt_t* options)
{
  // Start with an empty typechecker frame.
  memset(options, 0, sizeof(pass_opt_t));
  options->limit = PASS_ALL;
  frame_push(&options->check, NULL);
}
Esempio n. 3
0
void pass_opt_init(pass_opt_t* options)
{
  // Start with an empty typechecker frame.
  memset(options, 0, sizeof(pass_opt_t));
  options->limit = PASS_ALL;
  options->verbosity = VERBOSITY_INFO;
  options->check.errors = errors_alloc();
  frame_push(&options->check, NULL);
}
Esempio n. 4
0
File: pass.c Progetto: ozra/ponyc
bool type_passes(ast_t* type, pass_opt_t* options)
{
  ast_t* module = ast_parent(type);
  ast_t* package = ast_parent(module);

  frame_push(&options->check, NULL);
  frame_push(&options->check, package);
  frame_push(&options->check, module);

  bool ok = package_passes(type, options);

  if(ok)
    ok = program_passes(type, options);

  frame_pop(&options->check);
  frame_pop(&options->check);
  frame_pop(&options->check);

  return ok;
}
Esempio n. 5
0
ast_result_t ast_visit_scope(ast_t** ast, ast_visit_t pre, ast_visit_t post,
  pass_opt_t* options, pass_id pass)
{
  typecheck_t* t = &options->check;
  ast_t* module = ast_nearest(*ast, TK_MODULE);
  ast_t* package = ast_parent(module);
  assert(module != NULL);
  assert(package != NULL);

  frame_push(t, NULL);
  frame_push(t, package);
  frame_push(t, module);

  ast_result_t ret = ast_visit(ast, pre, post, options, pass);

  frame_pop(t);
  frame_pop(t);
  frame_pop(t);

  return ret;
}
Esempio n. 6
0
File: pass.c Progetto: jonas-l/ponyc
ast_result_t ast_visit_scope(ast_t** ast, ast_visit_t pre, ast_visit_t post,
  pass_opt_t* options, pass_id pass)
{
  typecheck_t* t = &options->check;
  bool pop = frame_push(t, NULL);

  ast_result_t ret = ast_visit(ast, pre, post, options, pass);

  if(pop)
    frame_pop(t);

  return ret;
}
Esempio n. 7
0
void jq_start(jq_state *jq, jv input, int flags) {
  jv_nomem_handler(jq->nomem_handler, jq->nomem_handler_data);
  jq_reset(jq);
  
  struct closure top = {jq->bc, -1};
  struct frame* top_frame = frame_push(jq, top, 0, 0);
  top_frame->retdata = 0;
  top_frame->retaddr = 0;

  stack_push(jq, input);
  stack_save(jq, jq->bc->code, stack_get_pos(jq));
  if (flags & JQ_DEBUG_TRACE) {
    jq->debug_trace_enabled = 1;
  } else {
    jq->debug_trace_enabled = 0;
  }
  jq->initial_execution = 1;
}
Esempio n. 8
0
void jq_init(struct bytecode* bc, jv input, jq_state **jq, int flags) {
  jq_state *new_jq;
  new_jq = jv_mem_alloc(sizeof(*new_jq));
  memset(new_jq, 0, sizeof(*new_jq));
  new_jq->path = jv_null();
  forkable_stack_init(&new_jq->data_stk, sizeof(data_stk_elem) * 100);
  forkable_stack_init(&new_jq->frame_stk, 1024);
  forkable_stack_init(&new_jq->fork_stk, 1024);
  
  stack_push(new_jq, input);
  struct closure top = {bc, -1};
  frame_push(&new_jq->frame_stk, top, 0);
  stack_save(new_jq, bc->code);
  stack_switch(new_jq);
  if (flags & JQ_DEBUG_TRACE) {
    new_jq->debug_trace_enabled = 1;
  } else {
    new_jq->debug_trace_enabled = 0;
  }
  new_jq->initial_execution = 1;
  *jq = new_jq;
}
Esempio n. 9
0
jv jq_next(jq_state *jq) {
  jv cfunc_input[MAX_CFUNCTION_ARGS];

  jv_nomem_handler(jq->nomem_handler, jq->nomem_handler_data);

  uint16_t* pc = stack_restore(jq);
  assert(pc);

  int backtracking = !jq->initial_execution;
  jq->initial_execution = 0;
  while (1) {
    uint16_t opcode = *pc;

    if (jq->debug_trace_enabled) {
      dump_operation(frame_current(jq)->bc, pc);
      printf("\t");
      const struct opcode_description* opdesc = opcode_describe(opcode);
      stack_ptr param = 0;
      if (!backtracking) {
        int stack_in = opdesc->stack_in;
        if (stack_in == -1) stack_in = pc[1];
        int i;
        for (i=0; i<stack_in; i++) {
          if (i == 0) {
            param = jq->stk_top;
          } else {
            printf(" | ");
            param = *stack_block_next(&jq->stk, param);
          }
          if (!param) break;
          jv_dump(jv_copy(*(jv*)stack_block(&jq->stk, param)), 0);
          //printf("<%d>", jv_get_refcnt(param->val));
          //printf(" -- ");
          //jv_dump(jv_copy(jq->path), 0);
        }
      } else {
        printf("\t<backtracking>");
      }

      printf("\n");
    }

    if (backtracking) {
      opcode = ON_BACKTRACK(opcode);
      backtracking = 0;
    }
    pc++;

    switch (opcode) {
    default: assert(0 && "invalid instruction");

    case LOADK: {
      jv v = jv_array_get(jv_copy(frame_current(jq)->bc->constants), *pc++);
      assert(jv_is_valid(v));
      jv_free(stack_pop(jq));
      stack_push(jq, v);
      break;
    }

    case DUP: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      break;
    }

    case DUP2: {
      jv keep = stack_pop(jq);
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, keep);
      stack_push(jq, v);
      break;
    }

    case SUBEXP_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      jq->subexp_nest++;
      break;
    }

    case SUBEXP_END: {
      assert(jq->subexp_nest > 0);
      jq->subexp_nest--;
      jv a = stack_pop(jq);
      jv b = stack_pop(jq);
      stack_push(jq, a);
      stack_push(jq, b);
      break;
    }
      
    case POP: {
      jv_free(stack_pop(jq));
      break;
    }

    case APPEND: {
      jv v = stack_pop(jq);
      uint16_t level = *pc++;
      uint16_t vidx = *pc++;
      jv* var = frame_local_var(jq, vidx, level);
      assert(jv_get_kind(*var) == JV_KIND_ARRAY);
      *var = jv_array_append(*var, v);
      break;
    }

    case INSERT: {
      jv stktop = stack_pop(jq);
      jv v = stack_pop(jq);
      jv k = stack_pop(jq);
      jv objv = stack_pop(jq);
      assert(jv_get_kind(objv) == JV_KIND_OBJECT);
      if (jv_get_kind(k) == JV_KIND_STRING) {
        stack_push(jq, jv_object_set(objv, k, v));
        stack_push(jq, stktop);
      } else {
        print_error(jq, jv_invalid_with_msg(jv_string_fmt("Cannot use %s as object key",
                                                          jv_kind_name(jv_get_kind(k)))));
        jv_free(stktop);
        jv_free(v);
        jv_free(k);
        jv_free(objv);
        goto do_backtrack;
      }
      break;
    }

    case ON_BACKTRACK(RANGE):
    case RANGE: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      jv max = stack_pop(jq);
      if (jv_get_kind(*var) != JV_KIND_NUMBER ||
          jv_get_kind(max) != JV_KIND_NUMBER) {
        print_error(jq, jv_invalid_with_msg(jv_string_fmt("Range bounds must be numeric")));
        jv_free(max);
        goto do_backtrack;
      } else if (jv_number_value(jv_copy(*var)) >= jv_number_value(jv_copy(max))) {
        /* finished iterating */
        goto do_backtrack;
      } else {
        jv curr = jv_copy(*var);
        *var = jv_number(jv_number_value(*var) + 1);

        struct stack_pos spos = stack_get_pos(jq);
        stack_push(jq, jv_copy(max));
        stack_save(jq, pc - 3, spos);

        stack_push(jq, curr);
      }
      break;
    }

      // FIXME: loadv/storev may do too much copying/freeing
    case LOADV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(*var), 0);
        printf("\n");
      }
      jv_free(stack_pop(jq));
      stack_push(jq, jv_copy(*var));
      break;
    }

      // Does a load but replaces the variable with null
    case LOADVN: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(*var), 0);
        printf("\n");
      }
      jv_free(stack_pop(jq));
      stack_push(jq, *var);
      *var = jv_null();
      break;
    }

    case STOREV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      jv* var = frame_local_var(jq, v, level);
      jv val = stack_pop(jq);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(val), 0);
        printf("\n");
      }
      jv_free(*var);
      *var = val;
      break;
    }

    case PATH_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jq->path);

      stack_save(jq, pc - 1, stack_get_pos(jq));

      stack_push(jq, jv_number(jq->subexp_nest));
      stack_push(jq, v);

      jq->path = jv_array();
      jq->subexp_nest = 0;
      break;
    }

    case PATH_END: {
      jv v = stack_pop(jq);
      jv_free(v); // discard value, only keep path

      int old_subexp_nest = (int)jv_number_value(stack_pop(jq));

      jv path = jq->path;
      jq->path = stack_pop(jq);

      struct stack_pos spos = stack_get_pos(jq);
      stack_push(jq, jv_copy(path));
      stack_save(jq, pc - 1, spos);

      stack_push(jq, path);
      jq->subexp_nest = old_subexp_nest;
      break;
    }

    case ON_BACKTRACK(PATH_BEGIN):
    case ON_BACKTRACK(PATH_END): {
      jv_free(jq->path);
      jq->path = stack_pop(jq);
      goto do_backtrack;
    }

    case INDEX:
    case INDEX_OPT: {
      jv t = stack_pop(jq);
      jv k = stack_pop(jq);
      path_append(jq, jv_copy(k));
      jv v = jv_get(t, k);
      if (jv_is_valid(v)) {
        stack_push(jq, v);
      } else {
        if (opcode == INDEX)
          print_error(jq, v);
        else
          jv_free(v);
        goto do_backtrack;
      }
      break;
    }


    case JUMP: {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }

    case JUMP_F: {
      uint16_t offset = *pc++;
      jv t = stack_pop(jq);
      jv_kind kind = jv_get_kind(t);
      if (kind == JV_KIND_FALSE || kind == JV_KIND_NULL) {
        pc += offset;
      }
      stack_push(jq, t); // FIXME do this better
      break;
    }

    case EACH: 
    case EACH_OPT: 
      stack_push(jq, jv_number(-1));
      // fallthrough
    case ON_BACKTRACK(EACH):
    case ON_BACKTRACK(EACH_OPT): {
      int idx = jv_number_value(stack_pop(jq));
      jv container = stack_pop(jq);

      int keep_going, is_last = 0;
      jv key, value;
      if (jv_get_kind(container) == JV_KIND_ARRAY) {
        if (opcode == EACH || opcode == EACH_OPT) idx = 0;
        else idx = idx + 1;
        int len = jv_array_length(jv_copy(container));
        keep_going = idx < len;
        is_last = idx == len - 1;
        if (keep_going) {
          key = jv_number(idx);
          value = jv_array_get(jv_copy(container), idx);
        }
      } else if (jv_get_kind(container) == JV_KIND_OBJECT) {
        if (opcode == EACH || opcode == EACH_OPT) idx = jv_object_iter(container);
        else idx = jv_object_iter_next(container, idx);
        keep_going = jv_object_iter_valid(container, idx);
        if (keep_going) {
          key = jv_object_iter_key(container, idx);
          value = jv_object_iter_value(container, idx);
        }
      } else {
        assert(opcode == EACH || opcode == EACH_OPT);
        if (opcode == EACH) {
          print_error(jq,
                      jv_invalid_with_msg(jv_string_fmt("Cannot iterate over %s",
                                                        jv_kind_name(jv_get_kind(container)))));
        }
        keep_going = 0;
      }

      if (!keep_going) {
        jv_free(container);
        goto do_backtrack;
      } else if (is_last) {
        // we don't need to make a backtrack point
        jv_free(container);
        path_append(jq, key);
        stack_push(jq, value);
      } else {
        struct stack_pos spos = stack_get_pos(jq);
        stack_push(jq, container);
        stack_push(jq, jv_number(idx));
        stack_save(jq, pc - 1, spos);
        path_append(jq, key);
        stack_push(jq, value);
      }
      break;
    }

    do_backtrack:
    case BACKTRACK: {
      pc = stack_restore(jq);
      if (!pc) {
        return jv_invalid();
      }
      backtracking = 1;
      break;
    }

    case FORK: {
      stack_save(jq, pc - 1, stack_get_pos(jq));
      pc++; // skip offset this time
      break;
    }

    case ON_BACKTRACK(FORK): {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }
      
    case CALL_BUILTIN: {
      int nargs = *pc++;
      jv top = stack_pop(jq);
      jv* in = cfunc_input;
      int i;
      in[0] = top;
      for (i = 1; i < nargs; i++) {
        in[i] = stack_pop(jq);
      }
      struct cfunction* function = &frame_current(jq)->bc->globals->cfunctions[*pc++];
      typedef jv (*func_1)(jv);
      typedef jv (*func_2)(jv,jv);
      typedef jv (*func_3)(jv,jv,jv);
      typedef jv (*func_4)(jv,jv,jv,jv);
      typedef jv (*func_5)(jv,jv,jv,jv,jv);
      switch (function->nargs) {
      case 1: top = ((func_1)function->fptr)(in[0]); break;
      case 2: top = ((func_2)function->fptr)(in[0], in[1]); break;
      case 3: top = ((func_3)function->fptr)(in[0], in[1], in[2]); break;
      case 4: top = ((func_4)function->fptr)(in[0], in[1], in[2], in[3]); break;
      case 5: top = ((func_5)function->fptr)(in[0], in[1], in[2], in[3], in[4]); break;
      default: return jv_invalid_with_msg(jv_string("Function takes too many arguments"));
      }
      
      if (jv_is_valid(top)) {
        stack_push(jq, top);
      } else {
        print_error(jq, top);
        goto do_backtrack;
      }
      break;
    }

    case CALL_JQ: {
      jv input = stack_pop(jq);
      uint16_t nclosures = *pc++;
      uint16_t* retaddr = pc + 2 + nclosures*2;
      struct frame* new_frame = frame_push(jq, make_closure(jq, pc),
                                           pc + 2, nclosures);
      new_frame->retdata = jq->stk_top;
      new_frame->retaddr = retaddr;
      pc = new_frame->bc->code;
      stack_push(jq, input);
      break;
    }

    case RET: {
      jv value = stack_pop(jq);
      assert(jq->stk_top == frame_current(jq)->retdata);
      uint16_t* retaddr = frame_current(jq)->retaddr;
      if (retaddr) {
        // function return
        pc = retaddr;
        frame_pop(jq);
      } else {
        // top-level return, yielding value
        struct stack_pos spos = stack_get_pos(jq);
        stack_push(jq, jv_null());
        stack_save(jq, pc - 1, spos);
        return value;
      }
      stack_push(jq, value);
      break;
    }
    case ON_BACKTRACK(RET): {
      // resumed after top-level return
      goto do_backtrack;
    }
    }
  }
}
Esempio n. 10
0
ast_result_t ast_visit(ast_t** ast, ast_visit_t pre, ast_visit_t post,
  pass_opt_t* options, pass_id pass)
{
  assert(ast != NULL);
  assert(*ast != NULL);

  pass_id ast_pass = (pass_id)ast_checkflag(*ast, AST_FLAG_PASS_MASK);

  if(ast_pass >= pass)  // This pass already done for this AST node
    return AST_OK;

  if(ast_checkflag(*ast, AST_FLAG_PRESERVE))  // Do not process this subtree
    return AST_OK;

  typecheck_t* t = &options->check;
  bool pop = frame_push(t, *ast);

  ast_result_t ret = AST_OK;
  bool ignore = false;

  if(pre != NULL)
  {
    switch(pre(ast, options))
    {
      case AST_OK:
        break;

      case AST_IGNORE:
        ignore = true;
        break;

      case AST_ERROR:
        ret = AST_ERROR;
        break;

      case AST_FATAL:
        record_ast_pass(*ast, pass);
        return AST_FATAL;
    }
  }

  if(!ignore && ((pre != NULL) || (post != NULL)))
  {
    ast_t* child = ast_child(*ast);

    while(child != NULL)
    {
      switch(ast_visit(&child, pre, post, options, pass))
      {
        case AST_OK:
          break;

        case AST_IGNORE:
          // Can never happen
          assert(0);
          break;

        case AST_ERROR:
          ret = AST_ERROR;
          break;

        case AST_FATAL:
          record_ast_pass(*ast, pass);
          return AST_FATAL;
      }

      child = ast_sibling(child);
    }
  }

  if(!ignore && post != NULL)
  {
    switch(post(ast, options))
    {
      case AST_OK:
      case AST_IGNORE:
        break;

      case AST_ERROR:
        ret = AST_ERROR;
        break;

      case AST_FATAL:
        record_ast_pass(*ast, pass);
        return AST_FATAL;
    }
  }

  if(pop)
    frame_pop(t);

  record_ast_pass(*ast, pass);
  return ret;
}
Esempio n. 11
0
void environ_pushframe(node_t *env_handle)
{
	frame_push(env_handle, NULL, NULL, 0);
}
Esempio n. 12
0
jv jq_next(jq_state *jq) {
  jv cfunc_input[MAX_CFUNCTION_ARGS];

  uint16_t* pc = stack_restore(jq);
  assert(pc);

  int backtracking = !jq->initial_execution;
  jq->initial_execution = 0;
  while (1) {
    uint16_t opcode = *pc;

    if (jq->debug_trace_enabled) {
      dump_operation(frame_current_bytecode(&jq->frame_stk), pc);
      printf("\t");
      const struct opcode_description* opdesc = opcode_describe(opcode);
      data_stk_elem* param = 0;
      int stack_in = opdesc->stack_in;
      if (stack_in == -1) stack_in = pc[1];
      for (int i=0; i<stack_in; i++) {
        if (i == 0) {
          param = forkable_stack_peek(&jq->data_stk);
        } else {
          printf(" | ");
          param = forkable_stack_peek_next(&jq->data_stk, param);
        }
        if (!param) break;
        jv_dump(jv_copy(param->val), 0);
        //printf("<%d>", jv_get_refcnt(param->val));
        //printf(" -- ");
        //jv_dump(jv_copy(jq->path), 0);
      }

      if (backtracking) printf("\t<backtracking>");

      printf("\n");
    }
    if (backtracking) {
      opcode = ON_BACKTRACK(opcode);
      backtracking = 0;
    }
    pc++;

    switch (opcode) {
    default: assert(0 && "invalid instruction");

    case LOADK: {
      jv v = jv_array_get(jv_copy(frame_current_bytecode(&jq->frame_stk)->constants), *pc++);
      assert(jv_is_valid(v));
      jv_free(stack_pop(jq));
      stack_push(jq, v);
      break;
    }

    case DUP: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      break;
    }

    case DUP2: {
      jv keep = stack_pop(jq);
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, keep);
      stack_push(jq, v);
      break;
    }

    case SUBEXP_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jv_copy(v));
      stack_push(jq, v);
      jq->subexp_nest++;
      break;
    }

    case SUBEXP_END: {
      assert(jq->subexp_nest > 0);
      jq->subexp_nest--;
      jv a = stack_pop(jq);
      jv b = stack_pop(jq);
      stack_push(jq, a);
      stack_push(jq, b);
      break;
    }
      
    case POP: {
      jv_free(stack_pop(jq));
      break;
    }

    case APPEND: {
      jv v = stack_pop(jq);
      uint16_t level = *pc++;
      uint16_t vidx = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, vidx);
      assert(jv_get_kind(*var) == JV_KIND_ARRAY);
      *var = jv_array_append(*var, v);
      break;
    }

    case INSERT: {
      jv stktop = stack_pop(jq);
      jv v = stack_pop(jq);
      jv k = stack_pop(jq);
      jv objv = stack_pop(jq);
      assert(jv_get_kind(objv) == JV_KIND_OBJECT);
      if (jv_get_kind(k) == JV_KIND_STRING) {
        stack_push(jq, jv_object_set(objv, k, v));
        stack_push(jq, stktop);
      } else {
        print_error(jv_invalid_with_msg(jv_string_fmt("Cannot use %s as object key",
                                                      jv_kind_name(jv_get_kind(k)))));
        jv_free(stktop);
        jv_free(v);
        jv_free(k);
        jv_free(objv);
        goto do_backtrack;
      }
      break;
    }

    case ON_BACKTRACK(RANGE):
    case RANGE: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, v);
      jv max = stack_pop(jq);
      if (jv_get_kind(*var) != JV_KIND_NUMBER ||
          jv_get_kind(max) != JV_KIND_NUMBER) {
        print_error(jv_invalid_with_msg(jv_string_fmt("Range bounds must be numeric")));
        jv_free(max);
        goto do_backtrack;
      } else if (jv_number_value(jv_copy(*var)) >= jv_number_value(jv_copy(max))) {
        /* finished iterating */
        goto do_backtrack;
      } else {
        jv curr = jv_copy(*var);
        *var = jv_number(jv_number_value(*var) + 1);

        stack_save(jq, pc - 3);
        stack_push(jq, jv_copy(max));
        stack_switch(jq);
        stack_push(jq, curr);
      }
      break;
    }

      // FIXME: loadv/storev may do too much copying/freeing
    case LOADV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, v);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(*var), 0);
        printf("\n");
      }
      jv_free(stack_pop(jq));
      stack_push(jq, jv_copy(*var));
      break;
    }

    case STOREV: {
      uint16_t level = *pc++;
      uint16_t v = *pc++;
      frame_ptr fp = frame_get_level(&jq->frame_stk, frame_current(&jq->frame_stk), level);
      jv* var = frame_local_var(fp, v);
      jv val = stack_pop(jq);
      if (jq->debug_trace_enabled) {
        printf("V%d = ", v);
        jv_dump(jv_copy(val), 0);
        printf("\n");
      }
      jv_free(*var);
      *var = val;
      break;
    }

    case PATH_BEGIN: {
      jv v = stack_pop(jq);
      stack_push(jq, jq->path);

      stack_save(jq, pc - 1);
      stack_switch(jq);

      stack_push(jq, jv_number(jq->subexp_nest));
      stack_push(jq, v);

      jq->path = jv_array();
      jq->subexp_nest = 0;
      break;
    }

    case PATH_END: {
      jv v = stack_pop(jq);
      jv_free(v); // discard value, only keep path

      int old_subexp_nest = (int)jv_number_value(stack_pop(jq));

      jv path = jq->path;
      jq->path = stack_pop(jq);

      stack_save(jq, pc - 1);
      stack_push(jq, jv_copy(path));
      stack_switch(jq);

      stack_push(jq, path);
      jq->subexp_nest = old_subexp_nest;
      break;
    }

    case ON_BACKTRACK(PATH_BEGIN):
    case ON_BACKTRACK(PATH_END): {
      jv_free(jq->path);
      jq->path = stack_pop(jq);
      goto do_backtrack;
    }

    case INDEX: {
      jv t = stack_pop(jq);
      jv k = stack_pop(jq);
      path_append(jq, jv_copy(k));
      jv v = jv_get(t, k);
      if (jv_is_valid(v)) {
        stack_push(jq, v);
      } else {
        print_error(v);
        goto do_backtrack;
      }
      break;
    }


    case JUMP: {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }

    case JUMP_F: {
      uint16_t offset = *pc++;
      jv t = stack_pop(jq);
      jv_kind kind = jv_get_kind(t);
      if (kind == JV_KIND_FALSE || kind == JV_KIND_NULL) {
        pc += offset;
      }
      stack_push(jq, t); // FIXME do this better
      break;
    }

    case EACH: 
      stack_push(jq, jv_number(-1));
      // fallthrough
    case ON_BACKTRACK(EACH): {
      int idx = jv_number_value(stack_pop(jq));
      jv container = stack_pop(jq);

      int keep_going;
      jv key, value;
      if (jv_get_kind(container) == JV_KIND_ARRAY) {
        if (opcode == EACH) idx = 0;
        else idx = idx + 1;
        keep_going = idx < jv_array_length(jv_copy(container));
        if (keep_going) {
          key = jv_number(idx);
          value = jv_array_get(jv_copy(container), idx);
        }
      } else if (jv_get_kind(container) == JV_KIND_OBJECT) {
        if (opcode == EACH) idx = jv_object_iter(container);
        else idx = jv_object_iter_next(container, idx);
        keep_going = jv_object_iter_valid(container, idx);
        if (keep_going) {
          key = jv_object_iter_key(container, idx);
          value = jv_object_iter_value(container, idx);
        }
      } else {
        assert(opcode == EACH);
        print_error(jv_invalid_with_msg(jv_string_fmt("Cannot iterate over %s",
                                                      jv_kind_name(jv_get_kind(container)))));
        keep_going = 0;
      }

      if (!keep_going) {
        jv_free(container);
        goto do_backtrack;
      } else {
        stack_save(jq, pc - 1);
        stack_push(jq, container);
        stack_push(jq, jv_number(idx));
        stack_switch(jq);
        path_append(jq, key);
        stack_push(jq, value);
      }
      break;
    }

    do_backtrack:
    case BACKTRACK: {
      pc = stack_restore(jq);
      if (!pc) {
        return jv_invalid();
      }
      backtracking = 1;
      break;
    }

    case FORK: {
      stack_save(jq, pc - 1);
      stack_switch(jq);
      pc++; // skip offset this time
      break;
    }

    case ON_BACKTRACK(FORK): {
      uint16_t offset = *pc++;
      pc += offset;
      break;
    }
      
    case CALL_BUILTIN: {
      int nargs = *pc++;
      jv top = stack_pop(jq);
      cfunc_input[0] = top;
      for (int i = 1; i < nargs; i++) {
        cfunc_input[i] = stack_pop(jq);
      }
      struct cfunction* func = &frame_current_bytecode(&jq->frame_stk)->globals->cfunctions[*pc++];
      top = cfunction_invoke(func, cfunc_input);
      if (jv_is_valid(top)) {
        stack_push(jq, top);
      } else {
        print_error(top);
        goto do_backtrack;
      }
      break;
    }

    case CALL_JQ: {
      uint16_t nclosures = *pc++;
      uint16_t* retaddr = pc + 2 + nclosures*2;
      frame_ptr new_frame = frame_push(&jq->frame_stk, 
                                       make_closure(&jq->frame_stk, frame_current(&jq->frame_stk), pc),
                                       retaddr);
      pc += 2;
      frame_ptr old_frame = forkable_stack_peek_next(&jq->frame_stk, new_frame);
      assert(nclosures == frame_self(new_frame)->bc->nclosures);
      for (int i=0; i<nclosures; i++) {
        *frame_closure_arg(new_frame, i) = make_closure(&jq->frame_stk, old_frame, pc);
        pc += 2;
      }

      pc = frame_current_bytecode(&jq->frame_stk)->code;
      break;
    }

    case RET: {
      uint16_t* retaddr = *frame_current_retaddr(&jq->frame_stk);
      if (retaddr) {
        // function return
        pc = retaddr;
        frame_pop(&jq->frame_stk);
      } else {
        // top-level return, yielding value
        jv value = stack_pop(jq);
        stack_save(jq, pc - 1);
        stack_push(jq, jv_null());
        stack_switch(jq);
        return value;
      }
      break;
    }
    case ON_BACKTRACK(RET): {
      // resumed after top-level return
      goto do_backtrack;
    }
    }
  }
}