truly thread-local vms; don't compile popen.scm

* ice-9/Makefile.am: Don't compile popen.scm, its behaviour at runtime
  is not consistent -- seems to miss some GC references? I suspect a bug
  in the compiler. In any case without popen.scm being compiled,
  continuations.test, r4rs.tes, and r5rs_pitfall.test do pass.

* libguile/threads.h (scm_i_thread):
* libguile/threads.c (thread_mark, guilify_self_2): Add a field for the
  thread's vm. Previously I had this as a fluid, but it seems that newly
  created threads share their fluid values from the creator thread; as
  expected, I guess. In any case one VM should not be active in two
  threads.

* libguile/vm.c (scm_the_vm): Change to access the thread-local vm,
  instead of accessing a fluid.
  (scm_the_vm_fluid): Removed.

* module/system/vm/vm.scm: Removed *the-vm*.

ice-9/Makefile.am

@@ -35,7 +35,7 @@ SOURCES = psyntax-pp.scm boot-9.scm \
 	debug.scm debugger.scm documentation.scm emacs.scm expect.scm	\
 	format.scm getopt-long.scm hcons.scm i18n.scm			\
 	lineio.scm ls.scm mapping.scm					\
-	networking.scm null.scm optargs.scm poe.scm popen.scm		\
+	networking.scm null.scm optargs.scm poe.scm		\
 	posix.scm q.scm r4rs.scm r5rs.scm			\
 	rdelim.scm receive.scm regex.scm runq.scm rw.scm		\
 	safe-r5rs.scm safe.scm session.scm slib.scm stack-catch.scm	\
@@ -48,6 +48,9 @@ SOURCES = psyntax-pp.scm boot-9.scm \
 # match.scm compiles, but then using it (via
 # snarf-check-and-output-texi) fails. need to figure out what the
 # problem is.
+#
+# popen.scm compiles, but then breaks the test suite via random lost gc
+# references. need to figure out what's going on there.
 # 
 # occam-channel and gds-client use goops, which is not yet vm-compatible
 # (it does some compilation-like optimizations for the interpreter), so
@@ -55,7 +58,7 @@ SOURCES = psyntax-pp.scm boot-9.scm \
 #
 # psyntax.scm needs help. fortunately it's only needed when recompiling
 # psyntax-pp.scm.
-NOCOMP_SOURCES = match.scm occam-channel.scm gds-client.scm psyntax.scm
+NOCOMP_SOURCES = match.scm occam-channel.scm gds-client.scm psyntax.scm popen.scm
 
 include $(top_srcdir)/guilec.mk
 

libguile/threads.c

@@ -158,6 +158,7 @@ thread_mark (SCM obj)
   scm_gc_mark (t->dynwinds);
   scm_gc_mark (t->active_asyncs);
   scm_gc_mark (t->continuation_root);
+  scm_gc_mark (t->vm);
   return t->dynamic_state;
 }
 
@@ -506,6 +507,7 @@ guilify_self_2 (SCM parent)
   scm_gc_register_collectable_memory (t, sizeof (scm_i_thread), "thread");
   t->continuation_root = scm_cons (t->handle, SCM_EOL);
   t->continuation_base = t->base;
+  t->vm = SCM_BOOL_F;
 
   if (scm_is_true (parent))
     t->dynamic_state = scm_make_dynamic_state (parent);

libguile/threads.h

@@ -111,6 +111,7 @@ typedef struct scm_i_thread {
   SCM_STACKITEM *continuation_base;
 
   /* For keeping track of the stack and registers. */
+  SCM vm;
   SCM_STACKITEM *base;
   SCM_STACKITEM *top;
   jmp_buf regs;

libguile/vm.c

@@ -360,8 +360,6 @@ vm_heapify_frames (SCM vm)
 
 scm_t_bits scm_tc16_vm;
 
-SCM scm_the_vm_fluid;
-
 static SCM
 make_vm (void)
 #define FUNC_NAME "make_vm"
@@ -372,6 +370,9 @@ make_vm (void)
   vp->stack_size  = VM_DEFAULT_STACK_SIZE;
   vp->stack_base  = scm_gc_malloc (vp->stack_size * sizeof (SCM),
 				   "stack-base");
+#ifdef VM_ENABLE_STACK_NULLING
+  memset (vp->stack_base, 0, vp->stack_size * sizeof (SCM));
+#endif
   vp->stack_limit = vp->stack_base + vp->stack_size - 3;
   vp->ip    	  = NULL;
   vp->sp    	  = vp->stack_base - 1;
@@ -448,14 +449,12 @@ SCM_DEFINE (scm_the_vm, "the-vm", 0, 0, 0,
 	    "")
 #define FUNC_NAME s_scm_the_vm
 {
-  SCM ret;
+  scm_i_thread *t = SCM_I_CURRENT_THREAD;
 
-  if (SCM_NFALSEP ((ret = scm_fluid_ref (scm_the_vm_fluid))))
-    return ret;
+  if (SCM_UNLIKELY (SCM_FALSEP ((t->vm))))
+    t->vm = make_vm ();
 
-  ret = make_vm ();
-  scm_fluid_set_x (scm_the_vm_fluid, ret);
-  return ret;
+  return t->vm;
 }
 #undef FUNC_NAME
 
@@ -771,10 +770,6 @@ scm_bootstrap_vm (void)
   scm_set_smob_free (scm_tc16_vm, vm_free);
   scm_set_smob_apply (scm_tc16_vm, scm_vm_apply, 1, 0, 1);
 
-  scm_the_vm_fluid = scm_permanent_object (scm_make_fluid ());
-  scm_fluid_set_x (scm_the_vm_fluid, make_vm ());
-  scm_c_define ("*the-vm*", scm_the_vm_fluid);
-
   scm_c_define ("load-compiled",
                 scm_c_make_gsubr ("load-compiled/vm", 1, 0, 0,
                                   scm_load_compiled_with_vm));

module/system/vm/vm.scm

@@ -22,7 +22,7 @@
 (define-module (system vm vm)
   #:use-module (system vm frame)
   #:use-module (system vm objcode)
-  #:export (vm? the-vm *the-vm* make-vm vm-version
+  #:export (vm? the-vm make-vm vm-version
            vm:ip vm:sp vm:fp vm:last-ip
 
            vm-load vm-return-value