compiler: opt-tail-calls compiler option.

* stdlib/comp-opts.tl (compile-opts): New slot, opt-tail-calls.
(%warning-syms%): Variable removed; this just lists the slots
of compile-opts, which can be obtained with the slots function.
Moreover, it is badly named, since there is now a non-diagnostic
option.
(*compile-opts*): Specify an initial value of : for opt-tail-calls.
This means that *opt-level* controls whether it is enabled.

* stdlib/compiler.tl: Update comment about optimization
levels, since level 2 now does tail calls.
(compiler comp-lambda-impl): Only enable tail calls if
the option has the default value : and *opt-level* is at
least two, or else if the option has value t.
(with-compile-opts): Recognize : as valid option value.
Don't refer to %warning-syms% but the slots of compile-opts.
We use load-time to avoid calculating this repeatedly.
The wording of the error message has to be adjusted since
not all options are diagnosic any more.

* autoload.c (compiler_set_entries): Add opt-tail-calls to
slot-name autoload triggers for the compiler module.

* txr.1: Mention tail calls and the opt-tail-calls option
in the description of *opt-level* 2. Document opt-tail-calls
under compile-opts section. We describe what tail calls are
there and also adjust the wording since not all options
diagnostic. Describe the three-valued system for code
generation options.

1 files changed, 9 insertions, 5 deletions

diff --git a/stdlib/compiler.tl b/stdlib/compiler.tl
index 37c5df56..6a49551a 100644
--- a/stdlib/compiler.tl
+++ b/stdlib/compiler.tl
@@ -342,7 +342,7 @@
 
 ;; 0 - no optimization
 ;; 1 - constant folding, algebraics.
-;; 2 - block elimination, frame elimination
+;; 2 - block elimination, frame elimination, self tail calls
 ;; 3 - lambda/combinator lifting
 ;; 4 - control-flow: jump-threading, dead code
 ;; 5 - data-flow: dead registers, useless regisers
@@ -1127,6 +1127,7 @@
                (*top-level* nil)
                (tfn *tail-fun*)
                (tpos nil)
+               (tco *compile-opts*.opt-tail-calls)
                (pars (new (fun-param-parser par-syntax form)))
                (need-frame (or (plusp pars.nfix) pars.rest))
                (nenv (if need-frame (new env up env co me) env))
@@ -1134,7 +1135,10 @@
           (when (> pars.nfix %max-lambda-fixed-args%)
             (compile-warning form "~s arguments in a lambda (max is ~s)"
                              pars.nfix %max-lambda-fixed-args%))
-          (when (and tfn (eq tfn.lambda form))
+          (when (and (caseq tco
+                       (: (>= *opt-level* 2))
+                       ((t) t))
+                     tfn (eq tfn.lambda form))
             (set tfn.env nenv
                  tfn.label (gensym "l")
                  tpos t))
@@ -2846,11 +2850,11 @@
 (defmacro usr:with-compile-opts (:form form . clauses)
   (match-case clauses
     (() ())
-    (((@(as op @(or nil t :warn :error @(integerp))) . @syms) . @rest)
+    (((@(as op @(or nil t :warn :error : @(integerp))) . @syms) . @rest)
      (each ((s syms))
-       (unless (member s %warning-syms%)
+       (unless (member s (load-time (slots 'compile-opts)))
          (compile-error form
-                        "~s isn't a recognized warning option" s)))
+                        "~s isn't a recognized compile option" s)))
      ^(compiler-let ((*compile-opts* (let ((co (copy *compile-opts*)))
                                        (set ,*(mappend (ret ^(co.,@1 ,op))
                                                        syms))