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, 22 insertions, 2 deletions

diff --git a/lisplib.c b/lisplib.c
index 6d9dcda7..b0f0fcc2 100644
--- a/lisplib.c
+++ b/lisplib.c
@@ -720,6 +720,25 @@ static val compiler_set_entries(val dlt, val fun)
   return nil;
 }
 
+static val debugger_instantiate(val set_fun)
+{
+  funcall1(set_fun, nil);
+  load(format(nil, lit("~adebugger"), stdlib_path, nao));
+  return nil;
+}
+
+static val debugger_set_entries(val dlt, val fun)
+{
+  val sys_name[] = {
+    lit("debugger"), lit("print-backtrace"),
+    nil
+  };
+
+  set_dlt_entries_sys(dlt, sys_name, fun);
+  return nil;
+}
+
+
 static val op_set_entries(val dlt, val fun)
 {
   val name[] = {
@@ -818,6 +837,7 @@ void lisplib_init(void)
   dlt_register(dl_table, stream_wrap_instantiate, stream_wrap_set_entries);
   dlt_register(dl_table, asm_instantiate, asm_set_entries);
   dlt_register(dl_table, compiler_instantiate, compiler_set_entries);
+  dlt_register(dl_table, debugger_instantiate, debugger_set_entries);
 
   if (!opt_compat || opt_compat >= 185)
     dlt_register(dl_table, op_instantiate, op_set_entries);
@@ -833,14 +853,14 @@ val lisplib_try_load(val sym)
   val fun = gethash(dl_table, sym);
 
   if (fun) {
-     int ds = debug_set_state(opt_dbg_autoload);
+     unsigned ds = debug_clear(opt_dbg_autoload ? 0 : DBG_ENABLE);
      val saved_dyn_env = dyn_env;
      dyn_env = make_env(nil, nil, dyn_env);
      env_vbind(dyn_env, package_s, system_package);
      env_vbind(dyn_env, package_alist_s, packages);
      funcall(fun);
      dyn_env = saved_dyn_env;
-     debug_set_state(ds);
+     debug_restore(ds);
      return t;
   }
   return nil;