debugger: initial backtrace support.

* debug.c (debug_state): Switch to unsigned, since this is now
a bitmask.
(sys_print_backtrace_s): New symbol variable.
(dbg_clear, dbg_set, dbg_restore): New static functions.
(debug_init): Initialize sys_print_backtrace_s. Register
dbg-clear, dbg-set, dbg-restore intrinsics. Register
dbg-enable, dbg-step, dbg-backtrace and dbg-all bitmask
variables, Lisp equivalents of DBG_ENABLE, DBG_SETP,
DBG_BACKTRACE and DBG_ALL.
(debug_dump_backtrace): New function.

* debug.h (opt_debugger): Declaration removed.
(debug_state): Declaration updated.
(DBG_ENABLE, DBG_STEP, DBG_BACKTRACE, DBG_ALL): New
preprocessor symbols.
(debug_set_state): Inline function removed.
(debug_clear, debug_set, debug_restore): New inline functions.
(dbg_backtrace, dbg_fcall_begin, dbg_fcall_end): New macros.
(debug_dump_backtrace): Declared.

* eval.c (error_trace): Invoke debug_dump_backtrace if support
is compiled in and backtraces are enabled.

* lib.c (do_generic_funcall): New function, copy of
generic_funcall.
(generic_funcall): Now a wrapper for do_generic_funcall which
registers fcall frames if backtrace support is enabled.
(funcall, funcall1, funcall2, funcall3, funcall4): Route to
slow generic_funcall path if backtraces are enabled.

* lisplib.c (debugger_instantiate, debugger_set_entries):
New static functions.
(lisplib_init): Autload support for debug module via above
new functions.
(lisplib_try_load): Save and restore debugger state in new
way using debug_set and debug_restore, with specific mask
values.

* parser.y (parse_once): Disable debugging in new way.

* share/txr/stdlib/debug.tl New file.

* sighal.h (EJ_DBG_MEMB, EJ_DBG_SAVE, EJ_DBG_REST): New
macros for saving/restoring debug state.
(EJ_OPT_MEMB, EJ_OPT_SAVE, EJ_OPT_REST): Reference the above
macros to include debug state in extended jump context.

* txr.c (help): Document --backtrace and that that -d
implies --backtrace.
(txr_main): Enable debugger using debug_set.
Provide new --backtrace option to enable backtraces only.

* unwind.c (args_s): New symbol variable.
(fcall_frame_type): New static variable.
(unwind_to_exit_point): Save pointer to original frame stack
and restore it when calling error_trace.  This is so that
error_trace can walk the stack to collect a backtrace.
(uw_find_frames_by_mask, uw_push_fcall): New functions.
(uw_late_init): Initialize args_s and fcall_frame_type.
gc-protect fcall_frame_type. Register uw-* variables
corresponding to the UW_* frame types.

* unwind.h (uw_frtype_t): New enum constant UW_FCALL.
(struct uw_fcall): New frame structure.
(union uw_frame): New member fc.
(uw_push_fcall, uw_find_frames_by_mask): Declared.

1 files changed, 66 insertions, 0 deletions

diff --git a/share/txr/stdlib/debugger.tl b/share/txr/stdlib/debugger.tl
new file mode 100644
index 00000000..9afab9ef
--- /dev/null
+++ b/share/txr/stdlib/debugger.tl
@@ -0,0 +1,66 @@
+;; Copyright 2019
+;; Kaz Kylheku <kaz@kylheku.com>
+;; Vancouver, Canada
+;; All rights reserved.
+;;
+;; Redistribution and use in source and binary forms, with or without
+;; modification, are permitted provided that the following conditions are met:
+;;
+;; 1. Redistributions of source code must retain the above copyright notice, this
+;;    list of conditions and the following disclaimer.
+;;
+;; 2. Redistributions in binary form must reproduce the above copyright notice,
+;;    this list of conditions and the following disclaimer in the documentation
+;;    and/or other materials provided with the distribution.
+;;
+;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+;; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+;; DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+;; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+;; SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+;; CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+;; OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+;; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+(defmacro with-disabled-debugging (. forms)
+  (let ((state (gensym)))
+    ^(let ((,state (dbg-clear dbg-all)))
+       (unwind-protect
+         (progn ,*forms)
+         (dbg-restore ,state)))))
+
+(defun make-command-env (command-table)
+  (let ((env (make-env )))
+    (mapdo (ado env-vbind env @1 ^(,@2)) command-table)
+    env))
+
+(defparml %dbg-commands% '((usr:? debugger-help "list command summary")
+                           (usr:bt print-backtrace "print backtrace")))
+
+(defparml %dbg-command-env% (make-command-env %dbg-commands%))
+
+(defun debugger-help ()
+  (mapdo (ap pprinl `@{@1 15} @3`) %dbg-commands%))
+
+(defun print-backtrace (: (*stdout* *stdout*) (prefix ""))
+  (with-resources ((imode (set-indent-mode *stdout* indent-off)
+                          (set-indent-mode *stdout* imode)))
+    (each ((fr (find-frames-by-mask uw-fcall)))
+      (let* ((fun fr.fun)
+             (args fr.args)
+             (name (if (functionp fun)
+                     (func-get-name fun)))
+             (kind
+               (cond
+                 ((interp-fun-p fun) "I")
+                 ((vm-fun-p fun) "V")
+                 ((functionp fun) "C")
+                 (t "O"))))
+        (put-string `@prefix @kind: `)
+        (prinl ^[,(or name fun) ,*args])))))
+
+(defun debugger ()
+  (with-disabled-debugging
+    (sys:repl nil *stdin* *stdout* %dbg-command-env%)))