Ligher weight debug instrumentation.

This speeds up the TXR Lisp interpreter, because do_eval
sets up a debug frame and uses debug_return.

* debug.c (debug_block_s): Symbol removed.
(debug_init): Remove initialization of debug_block_s.

* debug.h (debug_block_s): Declaration removed.
(debug_enter): Do not establish a named block or a catch block;
no time-wasting unwind stack manipulation at all.
The debug_depth variable is managed by the extended setjmp
context now.  Provide a return value variable, and a well-defined name to
branch to to exit from the debug block.
(debug_return): Do not use heavy-weight uw_block_return;
simply set the return variable and branch to debug_return_out
label.

* signal.h (EJ_DBG_MEMB, EJ_DBG_SAVE, EJ_DBG_REST,
EJ_OPT_MEMB, EJ_OPT_SAVE, EJ_OPT_REST): New macros.
(extended_jmp_buf): Define optional global state
variables using EJ_OPT_MEMB.
(extended_setjmp): Save and restore optional
globals using EJ_OPT_SAVE and EJ_OPT_RESTORE.
Now debug_depth is saved and restored if
debugging support is compiled in.

* match.c (open_data_source): Remove bogus debug_return
invocations which were uncovered here by changes to the macro.

* eval.c (do_eval, expand_macro): debug_return must now be after
debug_end, because it won't dynamically clean up frames that it doesn't
know about. The set_dyn_env is no longer unreachable in expand_macro;
it is now necessary because debug_return isn't doing the longjmp
that previously restored dyn_env.

1 files changed, 15 insertions, 17 deletions

diff --git a/debug.h b/debug.h
index 88695866..c14a304c 100644
--- a/debug.h
+++ b/debug.h
@@ -26,30 +26,28 @@
 
 extern int opt_debugger;
 extern int debug_depth;
-extern val debug_block_s;
 
 val debug(val form, val bindings, val data, val line, val pos, val base);
 
 #if CONFIG_DEBUG_SUPPORT
 
-#define debug_enter                                     \
-  {                                                     \
-    int debug_depth_save = debug_depth++;               \
-    uw_block_begin(debug_block_s, debug_result);        \
-    uw_simple_catch_begin {
-
-#define debug_leave                                     \
-    }                                                   \
-    uw_unwind {                                         \
-      debug_depth = debug_depth_save;                   \
-    }                                                   \
-    uw_catch_end;                                       \
-    uw_block_end;                                       \
-    return debug_result;                                \
+#define debug_enter                             \
+  {                                             \
+    int debug_depth_save = debug_depth++;       \
+    val debug_result = nil;                     \
+    (void) 0
+
+#define debug_leave                             \
+  debug_return_out:                             \
+    debug_depth = debug_depth_save;             \
+    return debug_result;                        \
   }
 
-#define debug_return(VAL)                               \
-  uw_block_return(debug_block_s, VAL)
+#define debug_return(VAL)               \
+  do {                                  \
+    debug_result = VAL;                 \
+    goto debug_return_out;              \
+  } while (0)
 
 INLINE val debug_check(val form, val bindings, val data, val line,
                        val pos, val base)