A small cleanup of malloc_bytes(), getting rid of a goto and a tiny

bit of optimization; ok tb@ asou@

diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 7c22665..b5eb212 100644 (file)
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: malloc.c,v 1.294 2023/12/04 07:01:45 otto Exp $       */
+/*     $OpenBSD: malloc.c,v 1.295 2023/12/19 06:59:28 otto Exp $       */
 /*
  * Copyright (c) 2008, 2010, 2011, 2016, 2023 Otto Moerbeek <otto@drijf.net>
  * Copyright (c) 2012 Matthew Dempsky <matthew@openbsd.org>
@@ -288,6 +288,7 @@ caller(struct dir_info *d)
 {
        struct btnode p;
        int level = DO_STATS;
+
        if (level == 0)
                return NULL;
 
@@ -1165,8 +1166,7 @@ fill_canary(char *ptr, size_t sz, size_t allocated)
 static void *
 malloc_bytes(struct dir_info *d, size_t size)
 {
-       u_int i, k, r, bucket, listnum;
-       int j;
+       u_int i, j, k, r, bucket, listnum;
        u_short *lp;
        struct chunk_info *bp;
        void *p;
@@ -1177,7 +1177,7 @@ malloc_bytes(struct dir_info *d, size_t size)
 
        bucket = find_bucket(size);
 
-       r = ((u_int)getrbyte(d) << 8) | getrbyte(d);
+       r = getrbyte(d);
        listnum = r % MALLOC_CHUNK_LISTS;
 
        /* If it's empty, make a page more of that size chunks */
@@ -1190,39 +1190,39 @@ malloc_bytes(struct dir_info *d, size_t size)
        if (bp->canary != (u_short)d->canary1 || bucket != bp->bucket)
                wrterror(d, "chunk info corrupted");
 
+       r /= MALLOC_CHUNK_LISTS;
+       /* do we need more random bits? */
+       if (bp->total > 256 / MALLOC_CHUNK_LISTS)
+               r = r << 8 | getrbyte(d);
        /* bias, as bp->total is not a power of 2 */
-       i = (r / MALLOC_CHUNK_LISTS) % bp->total;
+       i = r % bp->total;
 
-       /* potentially start somewhere in a short */
-       lp = &bp->bits[i / MALLOC_BITS];
-       j = i % MALLOC_BITS; /* j must be signed */
-       if (*lp >> j) {
-               k = ffs(*lp >> j);
-               if (k != 0) {
-                       k += j - 1;
-                       goto found;
-               }
-       }
-       /* no bit halfway, go to next full short */
+       j = i % MALLOC_BITS;
        i /= MALLOC_BITS;
-       for (;;) {
-               if (++i >= bp->offset)
-                       i = 0;
-               lp = &bp->bits[i];
-               if (*lp) {
-                       k = ffs(*lp) - 1;
-                       break;
+       lp = &bp->bits[i];
+       /* potentially start somewhere in a short */
+       if (j > 0 && *lp >> j)
+               k = ffs(*lp >> j) + j;
+       else {
+               /* no bit halfway, go to next full short */
+               for (;;) {
+                       if (*lp) {
+                               k = ffs(*lp);
+                               break;
+                       }
+                       if (++i >= bp->offset)
+                               i = 0;
+                       lp = &bp->bits[i];
                }
        }
-found:
-       *lp ^= 1 << k;
+       *lp ^= 1 << --k;
 
        /* If there are no more free, remove from free-list */
        if (--bp->free == 0)
                LIST_REMOVE(bp, entries);
 
        /* Adjust to the real offset of that chunk */
-       k += (lp - bp->bits) * MALLOC_BITS;
+       k += i * MALLOC_BITS;
 
        if (mopts.chunk_canaries && size > 0)
                bp->bits[bp->offset + k] = size;
@@ -1232,9 +1232,7 @@ found:
                STATS_SETFN(r, k, d->caller);
        }
 
-       k *= B2ALLOC(bucket);
-
-       p = (char *)bp->page + k;
+       p = (char *)bp->page + k * B2ALLOC(bucket);
        if (bucket > 0) {
                validate_junk(d, p, B2SIZE(bucket));
                if (mopts.chunk_canaries)