From d0bfc8779ccc48c342b3579283a19c8c7fe8d946 Mon Sep 17 00:00:00 2001
From: otto <>
Date: Thu, 18 Jan 2018 08:37:28 +0000
Subject: Move to ffs(3) for bitmask scanning. I played with this earlier, but
 at that time ffs function calls were generated instead of the compiler
 inlining the code.  Now that ffs is marked protected in libc this is handled
 better.  Thanks to kshe who prompted me to look at this again.

---
 src/lib/libc/stdlib/malloc.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

(limited to 'src/lib/libc/stdlib/malloc.c')

diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index b0083cb91e..40c602a1ae 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: malloc.c,v 1.239 2018/01/08 12:20:23 otto Exp $	*/
+/*	$OpenBSD: malloc.c,v 1.240 2018/01/18 08:37:28 otto Exp $	*/
 /*
  * Copyright (c) 2008, 2010, 2011, 2016 Otto Moerbeek <otto@drijf.net>
  * Copyright (c) 2012 Matthew Dempsky <matthew@openbsd.org>
@@ -931,7 +931,7 @@ malloc_bytes(struct dir_info *d, size_t size, void *f)
 	u_int i, r;
 	int j, listnum;
 	size_t k;
-	u_short	u, b, *lp;
+	u_short	*lp;
 	struct chunk_info *bp;
 	void *p;
 
@@ -960,15 +960,12 @@ malloc_bytes(struct dir_info *d, size_t size, void *f)
 	/* start somewhere in a short */
 	lp = &bp->bits[i / MALLOC_BITS];
 	if (*lp) {
-		b = *lp;
-		k = i % MALLOC_BITS;
-		u = 1 << k;
-		while (k < MALLOC_BITS) {
-			if (b & u)
-				goto found;
-			k++;
-			u <<= 1;
-		} 
+		j = i % MALLOC_BITS;
+		k = ffs(*lp >> j);
+		if (k != 0) {
+			k += j - 1;
+			goto found;
+		}
 	}
 	/* no bit halfway, go to next full short */
 	i /= MALLOC_BITS;
@@ -977,15 +974,8 @@ malloc_bytes(struct dir_info *d, size_t size, void *f)
 			i = 0;
 		lp = &bp->bits[i];
 		if (*lp) {
-			b = *lp;
-			k = 0;
-			u = 1;
-			for (;;) {
-				if (b & u)
-					goto found;
-				k++;
-				u <<= 1;
-			}
+			k = ffs(*lp) - 1;
+			break;
 		}
 	}
 found:
@@ -996,7 +986,7 @@ found:
 	}
 #endif
 
-	*lp ^= u;
+	*lp ^= 1 << k;
 
 	/* If there are no more free, remove from free-list */
 	if (--bp->free == 0)
-- 
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