New: virtual machine with assembler.

This commit is the start of compiler work to make TXR Lisp
execute faster. In six days of part time work, we now have a
register-style virtual machine with 32 instructions, handling
exceptions, unwind-protect, lexical closures, and global
environment access/mutation. We have a complete assembler and
disassembler for this machine. The assembler supports labels
with forward referencing with backpatching, and features
pseudo-ops: for instance the (mov ...) pseudo-instruction
chooses one of three kinds of specific move instruction based
on the operands.

* Makelfile (OBJS): Add vm.o.

* eval.c (lookup_sym_lisp1): Static function becomes external;
the virtual machine needs to use this to support that style
of lookup.

* genvmop.txr: New file. This is the generator for the
"vmop.h" header.

* lib.c (func_vm): New function.
(generic_funcall): Handle the FVM function type via new
vm_execute_closure function. In the variadic case, we want
to avoid the argument copying which we do for the sake of C
functions that get their fixed arguments directly, and then
just the trailing arguments. Thus the code is restructured a
bit in order to switch twice on the function type.
(init): Call vm_init.

* lib.h (functype_t): New enum member FVM.
(struct func): New member in the .f union: vm_desc.
(func_vm): Declared.

* lisplib.c (set_dlt_entries_impl): New static function,
formed from set_dlt_entries.
(set_dlt_entries): Reduced to wrapper for
set_dlt_entries_impl, passing in the user package.
(set_dlt_entries_sys): New static function: like
set_dlt_entries but targetting the sys package.
(asm_instantiate, asm_set_entries): New static functions.
(lisplib_init): Auto-load the sys:assembler class.

* share/txr/stdlib/asm.tl: New file.

* vm.c, vm.h, vmop.h: New files.

1 files changed, 32 insertions, 2 deletions

diff --git a/lisplib.c b/lisplib.c
index 503765b0..50c52356 100644
--- a/lisplib.c
+++ b/lisplib.c
@@ -46,10 +46,10 @@ val dl_table;
 int opt_dbg_autoload;
 val trace_loaded;
 
-void set_dlt_entries(val dlt, val *name, val fun)
+static void set_dlt_entries_impl(val dlt, val *name, val fun, val package)
 {
   for (; *name; name++) {
-    val sym = intern(*name, user_package);
+    val sym = intern(*name, package);
 
     if (fun)
       sethash(dlt, sym, fun);
@@ -58,6 +58,16 @@ void set_dlt_entries(val dlt, val *name, val fun)
   }
 }
 
+void set_dlt_entries(val dlt, val *name, val fun)
+{
+  set_dlt_entries_impl(dlt, name, fun, user_package);
+}
+
+static void set_dlt_entries_sys(val dlt, val *name, val fun)
+{
+  set_dlt_entries_impl(dlt, name, fun, system_package);
+}
+
 static void intern_only(val *name)
 {
   for (; *name; name++)
@@ -611,6 +621,25 @@ static val stream_wrap_instantiate(val set_fun)
   return nil;
 }
 
+static val asm_instantiate(val set_fun)
+{
+  funcall1(set_fun, nil);
+  load(format(nil, lit("~aasm.tl"), stdlib_path, nao));
+  return nil;
+}
+
+static val asm_set_entries(val dlt, val fun)
+{
+  val name[] = {
+    lit("assembler"),
+    nil
+  };
+
+  set_dlt_entries_sys(dlt, name, fun);
+  return nil;
+}
+
+
 static val op_set_entries(val dlt, val fun)
 {
   val name[] = {
@@ -670,6 +699,7 @@ void lisplib_init(void)
   dlt_register(dl_table, ffi_instantiate, ffi_set_entries);
   dlt_register(dl_table, doloop_instantiate, doloop_set_entries);
   dlt_register(dl_table, stream_wrap_instantiate, stream_wrap_set_entries);
+  dlt_register(dl_table, asm_instantiate, asm_set_entries);
 
   if (!opt_compat || opt_compat >= 185)
     dlt_register(dl_table, op_instantiate, op_set_entries);