Re: Minor simplification in byte-opt.el

["Mattias Engdegård" <mattiase@acm.org>]

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26 juli 2020 kl. 22.41 skrev Stefan Monnier <monnier@iro.umontreal.ca>:

> Could someone look over the patch below to confirm it's safe?

Thank you, looks decent to me. Good that you spotted the 1+/1-, I forgot about those.

> Also, as a result of this, there is only one call to
> `byte-optimize-form-code-walker` left, in `byte-optimize-form`, so maybe
> the two functions could be merged, tho it's probably not worth the trouble.

Maybe -- there seems to be little to gain from integrating them other than the elimination of the function call.

By the way, what about this little improvement?


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From cc6cbb304193c62354d3cb6b0b76f8ce066b2189 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Mon, 27 Jul 2020 11:27:00 +0200
Subject: [PATCH] Simplify and streamline optimizer clauses

* lisp/emacs-lisp/byte-opt.el (byte-optimize-form-code-walker):
Remove clause for 'with-output-to-temp-buffer', since it is a
macro and will have been expanded before reaching this point.
Move clauses for 'lambda' and 'closure' to avoid splitting
a cond jump table.
---
 lisp/emacs-lisp/byte-opt.el | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 6f801be545..48efff911f 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -391,13 +391,6 @@ byte-optimize-form-code-walker
 	   (and (nth 1 form)
 		(not for-effect)
 		form))
-	  ((eq (car-safe fn) 'lambda)
-	   (let ((newform (byte-compile-unfold-lambda form)))
-	     (if (eq newform form)
-		 ;; Some error occurred, avoid infinite recursion
-		 form
-	       (byte-optimize-form-code-walker newform for-effect))))
-	  ((eq (car-safe fn) 'closure) form)
 	  ((memq fn '(let let*))
 	   ;; recursively enter the optimizer for the bindings and body
 	   ;; of a let or let*.  This for depth-firstness: forms that
@@ -444,13 +437,6 @@ byte-optimize-form-code-walker
 	   ;; will be optimized away in the lap-optimize pass.
 	   (cons fn (byte-optimize-body (cdr form) for-effect)))
 
-	  ((eq fn 'with-output-to-temp-buffer)
-	   ;; this is just like the above, except for the first argument.
-	   (cons fn
-	     (cons
-	      (byte-optimize-form (nth 1 form) nil)
-	      (byte-optimize-body (cdr (cdr form)) for-effect))))
-
 	  ((eq fn 'if)
 	   (when (< (length form) 3)
 	     (byte-compile-warn "too few arguments for `if'"))
@@ -530,6 +516,15 @@ byte-optimize-form-code-walker
           ;; Needed as long as we run byte-optimize-form after cconv.
           ((eq fn 'internal-make-closure) form)
 
+	  ((eq (car-safe fn) 'lambda)
+	   (let ((newform (byte-compile-unfold-lambda form)))
+	     (if (eq newform form)
+		 ;; Some error occurred, avoid infinite recursion
+		 form
+	       (byte-optimize-form-code-walker newform for-effect))))
+
+	  ((eq (car-safe fn) 'closure) form)
+
           ((byte-code-function-p fn)
            (cons fn (mapcar #'byte-optimize-form (cdr form))))
 
-- 
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