[src/trunk]: src/usr.bin/make make(1): clean up RebuildTable for hash tables

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

details:   https://anonhg.NetBSD.org/src/rev/ca3a493ec9fd
branches:  trunk
changeset: 945303:ca3a493ec9fd
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Oct 25 17:58:53 2020 +0000

description:
make(1): clean up RebuildTable for hash tables

The previous code used ++ and -- a lot, it also reused variables a lot
for different purposes.

diffstat:

 usr.bin/make/hash.c |  46 ++++++++++++++++++++++++----------------------
 1 files changed, 24 insertions(+), 22 deletions(-)

diffs (70 lines):

diff -r 0aef038cc6fb -r ca3a493ec9fd usr.bin/make/hash.c
--- a/usr.bin/make/hash.c       Sun Oct 25 17:37:36 2020 +0000
+++ b/usr.bin/make/hash.c       Sun Oct 25 17:58:53 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: hash.c,v 1.48 2020/10/25 17:01:05 rillig Exp $ */
+/*     $NetBSD: hash.c,v 1.49 2020/10/25 17:58:53 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
@@ -79,7 +79,7 @@
 #include "make.h"
 
 /*     "@(#)hash.c     8.1 (Berkeley) 6/6/93"  */
-MAKE_RCSID("$NetBSD: hash.c,v 1.48 2020/10/25 17:01:05 rillig Exp $");
+MAKE_RCSID("$NetBSD: hash.c,v 1.49 2020/10/25 17:58:53 rillig Exp $");
 
 /*
  * The ratio of # entries to # buckets at which we rebuild the table to
@@ -203,29 +203,31 @@
 static void
 RebuildTable(HashTable *t)
 {
-       HashEntry *e, *next = NULL, **hp, **xp;
-       int i;
-       unsigned int mask, oldsize, newsize;
-       HashEntry **oldhp;
+       unsigned int oldSize = t->bucketsSize;
+       HashEntry **oldBuckets = t->buckets;
+       unsigned int newSize = 2 * oldSize;
+       unsigned int newMask = newSize - 1;
+       HashEntry **newBuckets = bmake_malloc(sizeof(*newBuckets) * newSize);
+       size_t i;
 
-       oldhp = t->buckets;
-       oldsize = t->bucketsSize;
-       newsize = oldsize << 1;
-       t->bucketsSize = (unsigned int)newsize;
-       t->bucketsMask = mask = newsize - 1;
-       t->buckets = hp = bmake_malloc(sizeof(*hp) * newsize);
-       i = (int)newsize;
-       while (--i >= 0)
-               *hp++ = NULL;
-       for (hp = oldhp, i = (int)oldsize; --i >= 0;) {
-               for (e = *hp++; e != NULL; e = next) {
-                       next = e->next;
-                       xp = &t->buckets[e->key_hash & mask];
-                       e->next = *xp;
-                       *xp = e;
+       for (i = 0; i < newSize; i++)
+               newBuckets[i] = NULL;
+
+       for (i = 0; i < oldSize; i++) {
+               HashEntry *he = oldBuckets[i];
+               while (he != NULL) {
+                       HashEntry *next = he->next;
+                       he->next = newBuckets[he->key_hash & newMask];
+                       newBuckets[he->key_hash & newMask] = he;
+                       he = next;
                }
        }
-       free(oldhp);
+
+       free(oldBuckets);
+
+       t->bucketsSize = newSize;
+       t->bucketsMask = newMask;
+       t->buckets = newBuckets;
        DEBUG5(HASH, "%s: %p size=%d entries=%d maxchain=%d\n",
               __func__, t, t->bucketsSize, t->numEntries, t->maxchain);
        t->maxchain = 0;