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, 61 insertions, 0 deletions

diff --git a/vmop.h b/vmop.h
new file mode 100644
index 00000000..6f4d518a
--- /dev/null
+++ b/vmop.h
@@ -0,0 +1,61 @@
+/* Copyright 2018
+ * Kaz Kylheku <kaz@kylheku.com>
+ * Vancouver, Canada
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+typedef enum vm_op {
+  NOOP = 0,
+  FRAME = 1,
+  DFRAME = 2,
+  END = 3,
+  FIN = 4,
+  CALL = 5,
+  APPLY = 6,
+  MOVRS = 7,
+  MOVSR = 8,
+  MOVRR = 9,
+  MOVRSI = 10,
+  MOVSMI = 11,
+  MOVRBI = 12,
+  JMP = 13,
+  IF = 14,
+  UWPROT = 15,
+  BLOCK = 16,
+  RETSR = 17,
+  RETRS = 18,
+  RETRR = 19,
+  CATCH = 20,
+  HANDLE = 21,
+  GETV = 22,
+  GETF = 23,
+  GETL1 = 24,
+  GETVB = 25,
+  GETFB = 26,
+  GETL1B = 27,
+  SETV = 28,
+  SETL1 = 29,
+  BINDV = 30,
+  CLOSE = 31,
+} vm_op_t;