runtime: Always build ldb but disable it when requested

Parts of the formerly conditionalized code are needed by other
features such as traceroot.

Since ldb is now always included, the :sb-ldb feature is now useless
if not misleading. It is probably not used, though (what could it be
used for?).

base-target-features.lisp-expr

@@ -95,10 +95,10 @@
  ;; readtable configured so that the system sources can be read.
  ; :sb-show
 
- ;; Build SBCL with the old CMU CL low level debugger, "ldb". In the
- ;; ideal world you would not need this unless you are messing with
- ;; SBCL at a very low level (e.g., trying to diagnose GC problems, or
- ;; trying to debug assembly code for a port to a new CPU). However,
+ ;; Enable the low level debugger, "ldb", by default. In the ideal
+ ;; world you would not need this unless you are messing with SBCL at
+ ;; a very low level (e.g., trying to diagnose GC problems, or trying
+ ;; to debug assembly code for a port to a new CPU). However,
  ;; experience shows that sooner or later everyone lose()'s, in which
  ;; case SB-LDB can at least provide an informative backtrace.
  :sb-ldb

doc/manual/support-and-bugs.texinfo

@@ -114,9 +114,10 @@ send a useful bug report then:
 
 @item
 @cindex ldb
-Compile SBCL with ldb support (feature @code{:sb-ldb}, see
-@file{base-target-features.lisp-expr}) and change @code{#define QSHOW_SIGNAL 0} to
-@code{#define QSHOW_SIGNAL 1} in @file{src/runtime/runtime.h}.
+Compile SBCL with ldb enabled (feature @code{:sb-ldb}, see
+@file{base-target-features.lisp-expr}) and change @code{#define
+QSHOW_SIGNAL 0} to @code{#define QSHOW_SIGNAL 1} in
+@file{src/runtime/runtime.h}.
 
 @item
 Isolate a smallish test case, run it.

src/compiler/generic/genesis.lisp

@@ -3126,7 +3126,6 @@ core and return a descriptor to it."
   (format stream "#define INTERNAL_ERROR_NARGS {~{~S~^, ~}}~2%"
           (map 'list #'cddr sb!c:+backend-internal-errors+)))
 
-#!+sb-ldb
 (defun write-tagnames-h (out)
   (labels
       ((pretty-name (symbol strip)
@@ -3745,7 +3744,6 @@ initially undefined function references:~2%")
         (out-to "constants" (write-constants-h stream))
         (out-to "errnames" (write-errnames-h stream))
         (out-to "gc-tables" (sb!vm::write-gc-tables stream))
-        #!+sb-ldb
         (out-to "tagnames" (write-tagnames-h stream))
         (let ((structs (sort (copy-list sb!vm:*primitive-objects*) #'string<
                              :key #'sb!vm:primitive-object-name)))

src/runtime/monitor.c

@@ -26,9 +26,6 @@
 #include "parse.h"
 #include "vars.h"
 
-/* Almost all of this file can be skipped if we're not supporting LDB. */
-#if defined(LISP_FEATURE_SB_LDB)
-
 #include "print.h"
 #include "arch.h"
 #include "interr.h"
@@ -531,20 +528,9 @@ throw_to_monitor()
     longjmp(curbuf, 1);
 }
 
-#endif /* defined(LISP_FEATURE_SB_LDB) */
-
 /* what we do when things go badly wrong at a low level */
 void
 monitor_or_something()
 {
-#if defined(LISP_FEATURE_SB_LDB)
     ldb_monitor();
-#else
-     fprintf(stderr,
-"The system is too badly corrupted or confused to continue at the Lisp\n\
-level. If the system had been compiled with the SB-LDB feature, we'd drop\n\
-into the LDB low-level debugger now. But there's no LDB in this build, so\n\
-we can't really do anything but just exit, sorry.\n");
-    exit(1);
-#endif
 }

src/runtime/parse.c

@@ -23,8 +23,6 @@
 #endif
 #include "runtime.h"
 
-#if defined(LISP_FEATURE_SB_LDB)
-
 #include "globals.h"
 #include "vars.h"
 #include "parse.h"
@@ -328,5 +326,3 @@ lispobj parse_lispobj(char **ptr)
 
     return result;
 }
-
-#endif /* defined(LISP_FEATURE_SB_LDB) */

src/runtime/print.c

@@ -207,9 +207,6 @@ fshow_fun(void __attribute__((__unused__)) *ignored,
     va_end(args);
 }
 
-/* This file can be skipped if we're not supporting LDB. */
-#if defined(LISP_FEATURE_SB_LDB)
-
 #include "monitor.h"
 #include "vars.h"
 #include "os.h"
@@ -964,13 +961,3 @@ void safely_show_lstring(struct vector * string, int quotes, FILE *s)
     fprintf(s, "#<[widetag=%02X]>", widetag_of(string->header));
   }
 }
-
-#else
-
-void
-brief_print(lispobj obj)
-{
-    printf("lispobj 0x%lx\n", (unsigned long)obj);
-}
-
-#endif /* defined(LISP_FEATURE_SB_LDB) */

src/runtime/runtime.c

@@ -448,7 +448,13 @@ main(int argc, char *argv[], char *envp[])
 
     /* other command line options */
     boolean end_runtime_options = 0;
-    boolean disable_lossage_handler_p = 0;
+    boolean disable_lossage_handler_p
+#if defined(LISP_FEATURE_SB_LDB)
+        = 0;
+#else
+        = 1;
+#endif
+
     boolean debug_environment_p = 0;
 
     lispobj initial_function;