# HG changeset patch
# User Rik <rik@octave.org>
# Date 1659116482 25200
# Node ID 92d897a2c1c3099c4f8c49e156e45d641418dd2c
# Parent  0758c713c6e6a9473973f457904493c49de85879
New runtime function __enable_vm_eval__() to control use of VM evaluator.

* libinterp/parse-tree/pt-vm-eval.cc (F__enable_vm_eval__): New file.  New
DEFUN for __enable_vm_eval__ protected by #ifdef on configuration variable
OCTAVE_ENABLE_VM_EVALUATOR.

* libinterp/parse-tree/module.mk: Add pt-vm-eval.cc to build system.

diff -r 0758c713c6e6 -r 92d897a2c1c3 libinterp/parse-tree/module.mk
--- a/libinterp/parse-tree/module.mk	Fri Jul 29 10:14:12 2022 -0700
+++ b/libinterp/parse-tree/module.mk	Fri Jul 29 10:41:22 2022 -0700
@@ -86,6 +86,7 @@
   %reldir%/pt-stmt.cc \
   %reldir%/pt-tm-const.cc \
   %reldir%/pt-unop.cc \
+  %reldir%/pt-vm-eval.cc \
   %reldir%/pt-walk.cc \
   %reldir%/pt.cc \
   %reldir%/token.cc
diff -r 0758c713c6e6 -r 92d897a2c1c3 libinterp/parse-tree/pt-vm-eval.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libinterp/parse-tree/pt-vm-eval.cc	Fri Jul 29 10:41:22 2022 -0700
@@ -0,0 +1,72 @@
+////////////////////////////////////////////////////////////////////////
+//
+// Copyright (C) 2022 The Octave Project Developers
+//
+// See the file COPYRIGHT.md in the top-level directory of this
+// distribution or <https://octave.org/copyright/>.
+//
+// This file is part of Octave.
+//
+// Octave is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Octave is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Octave; see the file COPYING.  If not, see
+// <https://www.gnu.org/licenses/>.
+//
+////////////////////////////////////////////////////////////////////////
+
+#if defined (HAVE_CONFIG_H)
+#  include "config.h"
+#endif
+
+#include "defun.h"
+#include "variables.h"
+
+OCTAVE_NAMESPACE_BEGIN
+
+// If TRUE, use VM evaluator rather than tree walker.
+
+static bool V__enable_vm_eval__ = false;
+
+DEFUN (__enable_vm_eval__, args, nargout,
+       doc: /* -*- texinfo -*-
+@deftypefn  {} {@var{val} =} __enable_vm_eval__ ()
+@deftypefnx {} {@var{old_val} =} __enable_vm_eval__ (@var{new_val})
+@deftypefnx {} {@var{old_val} =} __enable_vm_eval__ (@var{new_val}, "local")
+Query or set whether Octave uses a virtual machine (VM) for evaluation of
+parsed statements.
+
+The default value is false.  When false, Octave uses a traditional tree walker
+to evaluate statements parsed from m-code.  When true, Octave translates parsed
+statements to an intermediate representation that is then evaluated by a
+virtual machine.
+
+When called from inside a function with the @qcode{"local"} option, the setting
+is changed locally for the function and any subroutines it calls.  The original
+setting is restored when exiting the function.
+@end deftypefn */)
+{
+#if defined (OCTAVE_ENABLE_VM_EVALUATOR)
+
+  return set_internal_variable (V__enable_vm_eval__, args, nargout,
+                                "__enable_vm_eval__");
+
+#else
+
+  octave_unused_parameter (args);
+
+  err_disabled_feature ("vm-evaluator",
+                        "using a Virtual Machine for statement evaluation");
+
+#endif
+}
+
+OCTAVE_NAMESPACE_END