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, 14 insertions, 1 deletions

diff --git a/txr.c b/txr.c
index 4a69c0ba..4de8c3f7 100644
--- a/txr.c
+++ b/txr.c
@@ -111,7 +111,7 @@ static void help(void)
 "-l                     If dumping bindings, use TXR Lisp format.\n"
 "-i                     Interactive TXR Lisp listener mode.\n"
 "                       (Requires compiled-in support.)\n"
-"-d                     Debugger mode.\n"
+"-d                     Enable debugger. Implies --backtrace.\n"
 "-n                     Noninteractive input mode for standard input stream,\n"
 "                       even if its connected to a terminal device.\n"
 "                       Also, forces the interactive listener into\n"
@@ -144,6 +144,7 @@ static void help(void)
 "--compiled             Treat unsuffixed query files as compiled TXR Lisp.\n"
 "--lisp-bindings        Synonym for -l\n"
 "--debugger             Synonym for -d\n"
+"--backtrace            Enable backtraces.\n"
 "--noninteractive       Synonym for -n\n"
 "--compat=N             Synonym for -C N\n"
 "--gc-delta=N           Invoke garbage collection when malloc activity\n"
@@ -730,6 +731,7 @@ int txr_main(int argc, char **argv)
         drop_privilege();
 #if CONFIG_DEBUG_SUPPORT
         opt_debugger = 1;
+        debug_set(DBG_ENABLE | DBG_BACKTRACE);
         continue;
 #else
         no_dbg_support(arg);
@@ -740,6 +742,7 @@ int txr_main(int argc, char **argv)
 #if CONFIG_DEBUG_SUPPORT
         opt_debugger = 1;
         opt_dbg_autoload = 1;
+        debug_set(DBG_ENABLE | DBG_BACKTRACE);
         continue;
 #else
         no_dbg_support(opt);
@@ -750,6 +753,7 @@ int txr_main(int argc, char **argv)
 #if CONFIG_DEBUG_SUPPORT
         opt_debugger = 1;
         opt_dbg_expansion = 1;
+        debug_set(DBG_ENABLE | DBG_BACKTRACE);
         continue;
 #else
         no_dbg_support(opt);
@@ -770,6 +774,14 @@ int txr_main(int argc, char **argv)
                  prog_string, arg, nao);
           return EXIT_FAILURE;
         }
+      } else if (equal(opt, lit("backtrace"))) {
+#if CONFIG_DEBUG_SUPPORT
+        debug_set(DBG_BACKTRACE);
+        continue;
+#else
+        no_dbg_support(arg);
+        return EXIT_FAILURE;
+#endif
       } else if (equal(opt, lit("noninteractive"))) {
         opt_noninteractive = 1;
         stream_set_prop(std_input, real_time_k, nil);
@@ -965,6 +977,7 @@ int txr_main(int argc, char **argv)
           drop_privilege();
 #if CONFIG_DEBUG_SUPPORT
           opt_debugger = 1;
+          debug_set(DBG_ENABLE | DBG_BACKTRACE);
 #else
           no_dbg_support(opch);
           return EXIT_FAILURE;