[src/trunk]: src/usr.bin/make make(1): make GetActuallyIncludingFile faster

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ada2eac36ab1
branches:  trunk
changeset: 954528:ada2eac36ab1
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Sep 05 18:31:03 2020 +0000

description:
make(1): make GetActuallyIncludingFile faster

In deeply nested includes, starting the search from the inner end is
faster since it needs fewer comparisons.

diffstat:

 usr.bin/make/parse.c |  17 ++++++++---------
 1 files changed, 8 insertions(+), 9 deletions(-)

diffs (49 lines):

diff -r e11263f9cb49 -r ada2eac36ab1 usr.bin/make/parse.c
--- a/usr.bin/make/parse.c      Sat Sep 05 18:18:05 2020 +0000
+++ b/usr.bin/make/parse.c      Sat Sep 05 18:31:03 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: parse.c,v 1.281 2020/09/05 18:18:05 rillig Exp $       */
+/*     $NetBSD: parse.c,v 1.282 2020/09/05 18:31:03 rillig Exp $       */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -69,14 +69,14 @@
  */
 
 #ifndef MAKE_NATIVE
-static char rcsid[] = "$NetBSD: parse.c,v 1.281 2020/09/05 18:18:05 rillig Exp $";
+static char rcsid[] = "$NetBSD: parse.c,v 1.282 2020/09/05 18:31:03 rillig Exp $";
 #else
 #include <sys/cdefs.h>
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)parse.c    8.3 (Berkeley) 3/19/94";
 #else
-__RCSID("$NetBSD: parse.c,v 1.281 2020/09/05 18:18:05 rillig Exp $");
+__RCSID("$NetBSD: parse.c,v 1.282 2020/09/05 18:31:03 rillig Exp $");
 #endif
 #endif /* not lint */
 #endif
@@ -2343,17 +2343,16 @@
 static const char *
 GetActuallyIncludingFile(void)
 {
-    const char *filename = NULL;
     size_t i;
 
     /* XXX: Stack was supposed to be an opaque data structure. */
-    for (i = 0; i < includes.len; i++) {
-       IFile *parent = includes.items[i];
-       IFile *child = (i + 1 < includes.len) ? includes.items[i + 1] : curFile;
+    for (i = includes.len; i > 0; i--) {
+       IFile *parent = includes.items[i - 1];
+       IFile *child = (i < includes.len) ? includes.items[i] : curFile;
        if (!child->fromForLoop)
-           filename = parent->fname;
+           return parent->fname;
     }
-    return filename;
+    return NULL;
 }
 
 /* Set .PARSEDIR/.PARSEFILE to the given filename, as well as