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master 68c09c6: Better CPS conversion of multi-binding `let`
From: |
Mattias Engdegård |
Subject: |
master 68c09c6: Better CPS conversion of multi-binding `let` |
Date: |
Tue, 30 Nov 2021 07:04:05 -0500 (EST) |
branch: master
commit 68c09c6b741be5005b90152c59e781cb0f80704d
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>
Better CPS conversion of multi-binding `let`
* lisp/emacs-lisp/generator.el (cps--transform-1):
Don't translate single-binding `let` into `let*` with an extra
temporary variable; it just adds two more useless states.
---
lisp/emacs-lisp/generator.el | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/lisp/emacs-lisp/generator.el b/lisp/emacs-lisp/generator.el
index 2075ac4..4e286ed 100644
--- a/lisp/emacs-lisp/generator.el
+++ b/lisp/emacs-lisp/generator.el
@@ -291,8 +291,15 @@ DYNAMIC-VAR bound to STATIC-VAR."
(cps--transform-1 `(progn ,@rest)
next-state)))
- ;; Process `let' in a helper function that transforms it into a
- ;; let* with temporaries.
+ (`(,(or 'let 'let*) () . ,body)
+ (cps--transform-1 `(progn ,@body) next-state))
+
+ (`(let (,binding) . ,body)
+ (cps--transform-1 `(let* (,binding) ,@body) next-state))
+
+ ;; Transform multi-variable `let' into `let*':
+ ;; (let ((v1 e1) ... (vN eN)) BODY)
+ ;; -> (let* ((t1 e1) ... (tN eN) (v1 t1) (vN tN)) BODY)
(`(let ,bindings . ,body)
(let* ((bindings (cl-loop for binding in bindings
@@ -315,9 +322,6 @@ DYNAMIC-VAR bound to STATIC-VAR."
;; Process `let*' binding: process one binding at a time. Flatten
;; lexical bindings.
- (`(let* () . ,body)
- (cps--transform-1 `(progn ,@body) next-state))
-
(`(let* (,binding . ,more-bindings) . ,body)
(let* ((var (if (symbolp binding) binding (car binding)))
(value-form (car (cdr-safe binding)))
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