From 46d7d44894843bf30e9bc84473195c6ab892b752 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Mattias=20Engdeg=C3=A5rd?= Date: Tue, 20 Jul 2021 15:46:32 +0200 Subject: [PATCH] Strength-reduce (eq X nil) to (not X) * lisp/emacs-lisp/byte-opt.el (byte-optimize-eq): New optimisation, which results in better test and branch code generation where it applies. --- lisp/emacs-lisp/byte-opt.el | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el index 2fff0bd4a5f..7ed04b32e97 100644 --- a/lisp/emacs-lisp/byte-opt.el +++ b/lisp/emacs-lisp/byte-opt.el @@ -969,6 +969,12 @@ See Info node `(elisp) Integer Basics'." ;; Arity errors reported elsewhere. form))) +(defun byte-optimize-eq (form) + (byte-optimize-binary-predicate + (pcase (cdr form) + ((or `(,x nil) `(nil ,x)) `(not ,x)) + (_ 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. Same with fixnums. @@ -1056,7 +1062,7 @@ See Info node `(elisp) Integer Basics'." (put 'min 'byte-optimizer #'byte-optimize-min-max) (put '= 'byte-optimizer #'byte-optimize-binary-predicate) -(put 'eq 'byte-optimizer #'byte-optimize-binary-predicate) +(put 'eq 'byte-optimizer #'byte-optimize-eq) (put 'eql 'byte-optimizer #'byte-optimize-equal) (put 'equal 'byte-optimizer #'byte-optimize-equal) (put 'string= 'byte-optimizer #'byte-optimize-binary-predicate) -- 2.39.2