From d875f05b0632c8e639d4d033f3654012080fb8ef Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 29 Aug 2019 07:06:02 -0700
Subject: compiler: mac params: eliminate plen variable.

* share/txr/stdlib/compiler.tl (expand-bind-mac-params):
Remove the plen gensym. We don't need to store the form length
in a variable, because the generated length check code
references the value exactly once. Let's just propagate that
the length calculating expression into that code.
---
 share/txr/stdlib/compiler.tl | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/share/txr/stdlib/compiler.tl b/share/txr/stdlib/compiler.tl
index 60411e39..0fdf77ba 100644
--- a/share/txr/stdlib/compiler.tl
+++ b/share/txr/stdlib/compiler.tl
@@ -1373,7 +1373,7 @@
 
 (defun expand-bind-mac-params (ctx-form err-form params menv-var
                                obj-var strict err-block body)
-  (let (gen-stk stmt vars (plen (if (and strict (neq strict t)) (gensym))))
+  (let (gen-stk stmt vars)
     (labels ((get-gen ()
                (or (pop gen-stk) (gensym)))
              (put-gen (g)
@@ -1398,9 +1398,6 @@
                             vars)))
                  (let ((pars (new (mac-param-parser par-syntax ctx-form))))
                    (progn
-                     (when plen
-                       (emit-var plen ^(if (consp ,obj-var)
-                                         (len ,obj-var) 0)))
                      (cond
                        ((eq strict t)
                         (emit-stmt
@@ -1411,11 +1408,13 @@
                        ((null strict))
                        ((symbolp strict)
                         (emit-stmt
-                          (if pars.rest
-                            ^(unless (<= ,pars.nreq ,plen)
-                               (return-from ,err-block ',strict))
-                            ^(unless (<= ,pars.nreq ,plen ,pars.nfix)
-                               (return-from ,err-block ',strict))))))
+                          (let ((len-expr ^(if (consp ,obj-var)
+                                             (len ,obj-var) 0)))
+                            (if pars.rest
+                              ^(unless (<= ,pars.nreq ,len-expr)
+                                 (return-from ,err-block ',strict))
+                              ^(unless (<= ,pars.nreq ,len-expr ,pars.nfix)
+                                 (return-from ,err-block ',strict)))))))
                      (each ((k pars.key))
                        (tree-bind (key . sym) k
                          (caseq key
@@ -1478,7 +1477,7 @@
       (expand-rec params obj-var nil)
       (when stmt
         (push ^(,(gensym) (progn ,*(nreverse stmt))) vars))
-      ^(let* (,*(if plen ^(,plen)) ,*gen-stk ,*(nreverse vars))
+      ^(let* (,*gen-stk ,*(nreverse vars))
          ,*body))))
 
 (defun expand-defvarl (form)
-- 
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