[Emacs-diffs] master d8aba87: Strength-reduce `equal', `eql', `member' and `memql'

[Mattias Engdegård]

branch: master
commit d8aba87a0d5ef84dfedf4c6a73884fa6dc455b24
Author: Mattias Engdegård <address@hidden>
Commit: Mattias Engdegård <address@hidden>

    Strength-reduce `equal', `eql', `member' and `memql'
    
    When comparing against symbols, turn `equal' and `eql' into `eq',
    and `member' and `memql' into `memq'.
    
    * lisp/emacs-lisp/byte-opt.el (byte-optimize--constant-symbol-p)
    (byte-optimize-equal, byte-optimize-member): New.
    (member, memql, equal, eql): Use new byte-optimizers.
---
 lisp/emacs-lisp/byte-opt.el | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 2e09601..ecaa845 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -834,6 +834,36 @@
                       (if (= 1 (length (cdr form))) "" "s"))
     form))
 
+(defun byte-optimize--constant-symbol-p (expr)
+  "Whether EXPR is a constant symbol."
+  (and (macroexp-const-p expr) (symbolp (eval expr))))
+
+(defun byte-optimize-equal (form)
+  ;; Replace `equal' or `eql' with `eq' if at least one arg is a symbol.
+  (byte-optimize-binary-predicate
+   (if (= (length (cdr form)) 2)
+       (if (or (byte-optimize--constant-symbol-p (nth 1 form))
+               (byte-optimize--constant-symbol-p (nth 2 form)))
+           (cons 'eq (cdr form))
+         form)
+     ;; Arity errors reported elsewhere.
+     form)))
+
+(defun byte-optimize-member (form)
+  ;; Replace `member' or `memql' with `memq' if the first arg is a symbol,
+  ;; or the second arg is a list of symbols.
+  (if (= (length (cdr form)) 2)
+      (if (or (byte-optimize--constant-symbol-p (nth 1 form))
+              (let ((arg2 (nth 2 form)))
+                (and (macroexp-const-p arg2)
+                     (let ((listval (eval arg2)))
+                       (and (listp listval)
+                            (not (memq nil (mapcar #'symbolp listval))))))))
+          (cons 'memq (cdr form))
+        form)
+    ;; Arity errors reported elsewhere.
+    form))
+
 (defun byte-optimize-memq (form)
   ;; (memq foo '(bar)) => (and (eq foo 'bar) '(bar))
   (if (/= (length (cdr form)) 2)
@@ -879,6 +909,8 @@
 
 (put 'identity 'byte-optimizer 'byte-optimize-identity)
 (put 'memq 'byte-optimizer 'byte-optimize-memq)
+(put 'memql  'byte-optimizer 'byte-optimize-member)
+(put 'member 'byte-optimizer 'byte-optimize-member)
 
 (put '+   'byte-optimizer 'byte-optimize-plus)
 (put '*   'byte-optimizer 'byte-optimize-multiply)
@@ -889,7 +921,8 @@
 
 (put '=   'byte-optimizer 'byte-optimize-binary-predicate)
 (put 'eq  'byte-optimizer 'byte-optimize-binary-predicate)
-(put 'equal   'byte-optimizer 'byte-optimize-binary-predicate)
+(put 'eql   'byte-optimizer 'byte-optimize-equal)
+(put 'equal 'byte-optimizer 'byte-optimize-equal)
 (put 'string= 'byte-optimizer 'byte-optimize-binary-predicate)
 (put 'string-equal 'byte-optimizer 'byte-optimize-binary-predicate)