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

bit of optimization; ok tb@ asou@

1 files changed, 27 insertions, 29 deletions

diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index 7c226657df..b5eb212227 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/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)