diff options
Diffstat (limited to 'lisp/emacs-lisp')
| -rw-r--r-- | lisp/emacs-lisp/byte-opt.el | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el index 82a5cf0a75a..b4eaf4ff5eb 100644 --- a/lisp/emacs-lisp/byte-opt.el +++ b/lisp/emacs-lisp/byte-opt.el @@ -31,7 +31,7 @@ ;; "No matter how hard you try, you can't make a racehorse out of a pig. ;; You can, however, make a faster pig." ;; -;; Or, to put it another way, the emacs byte compiler is a VW Bug. This code +;; Or, to put it another way, the Emacs byte compiler is a VW Bug. This code ;; makes it be a VW Bug with fuel injection and a turbocharger... You're ;; still not going to make it go faster than 70 mph, but it might be easier ;; to get it there. @@ -1014,12 +1014,21 @@ form)) (defun byte-optimize-if (form) + ;; (if (progn <insts> <test>) <rest>) ==> (progn <insts> (if <test> <rest>)) ;; (if <true-constant> <then> <else...>) ==> <then> ;; (if <false-constant> <then> <else...>) ==> (progn <else...>) ;; (if <test> nil <else...>) ==> (if (not <test>) (progn <else...>)) ;; (if <test> <then> nil) ==> (if <test> <then>) (let ((clause (nth 1 form))) - (cond ((byte-compile-trueconstp clause) + (cond ((eq (car clause) 'progn) + (if (null (cddr clause)) + ;; A trivial `progn'. + (byte-optimize-if `(if ,(cadr clause) ,@(nthcdr 2 form))) + (nconc (butlast clause) + (list + (byte-optimize-if + `(if ,(car (last clause)) ,@(nthcdr 2 form))))))) + ((byte-compile-trueconstp clause) (nth 2 form)) ((null clause) (if (nthcdr 4 form) @@ -1326,7 +1335,7 @@ ;; This list contains numbers, which are pc values, ;; before each instruction. (defun byte-decompile-bytecode (bytes constvec) - "Turns BYTECODE into lapcode, referring to CONSTVEC." + "Turn BYTECODE into lapcode, referring to CONSTVEC." (let ((byte-compile-constants nil) (byte-compile-variables nil) (byte-compile-tag-number 0)) |