~ chicken-core (chicken-5) 6b9ebc427aa2b3bcd9ae30e7258e9b9ffe0a4bc8
commit 6b9ebc427aa2b3bcd9ae30e7258e9b9ffe0a4bc8
Author: Peter Bex <peter@more-magic.net>
AuthorDate: Thu Dec 15 23:44:35 2016 +0100
Commit: felix <felix@call-with-current-continuation.org>
CommitDate: Thu Jan 12 12:17:57 2017 +0100
Statically determine if av can be reused or not.
This is faster due to avoiding branch prediction misses.
Signed-off-by: felix <felix@call-with-current-continuation.org>
diff --git a/c-backend.scm b/c-backend.scm
index 3bb2171b..a5e0f5d9 100644
--- a/c-backend.scm
+++ b/c-backend.scm
@@ -491,19 +491,27 @@
(let* ((n (length args))
(avl (+ n (if selfarg 1 0)))
(caller-has-av? (not (or (lambda-literal-customizable ll)
- (lambda-literal-direct ll)))))
+ (lambda-literal-direct ll))))
+ (caller-argcount (lambda-literal-argument-count ll))
+ (caller-rest-mode (lambda-literal-rest-argument-mode ll)))
;; Try to re-use argvector from current function if it is
;; large enough. push-args gets used only for functions in
;; CPS context, so callee never returns to current function.
;; And even so, av[] is already copied into temporaries.
- (cond (caller-has-av?
- (gen #t "C_word *av2;")
- (gen #t "if(c >= " avl ") {")
- (gen #t " av2=av; /* Re-use our own argvector */")
- (gen #t "} else {")
- (gen #t " av2=C_alloc(" avl ");")
- (gen #t "}"))
- (else (gen #t "C_word av2[" avl "];")))
+ (cond
+ ((or (not caller-has-av?) ; Argvec missing or
+ (and (< caller-argcount avl) ; known to be too small?
+ (eq? caller-rest-mode 'none)))
+ (gen #t "C_word av2[" avl "];"))
+ ((>= caller-argcount avl) ; Argvec known to be re-usable?
+ (gen #t "C_word *av2=av; /* Re-use our own argvector */"))
+ (else ; Need to determine dynamically. This is slower.
+ (gen #t "C_word *av2;")
+ (gen #t "if(c >= " avl ") {")
+ (gen #t " av2=av; /* Re-use our own argvector */")
+ (gen #t "} else {")
+ (gen #t " av2=C_alloc(" avl ");")
+ (gen #t "}")))
(when selfarg (gen #t "av2[0]=" selfarg ";"))
(do ((j (if selfarg 1 0) (add1 j))
(args args (cdr args)))
Trap