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authorDenys Vlasenko <vda.linux@googlemail.com>2010-01-18 04:22:34 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2010-01-18 04:22:34 (GMT)
commit032bf6553346537cb02d0406c05548c8aa23c81f (patch)
tree231b695138da8661547e331c3b43c7ee438c5194
parentd4a7728dc3b37e2956034f18fc26c04bc0aa2b0e (diff)
downloadbusybox-032bf6553346537cb02d0406c05548c8aa23c81f.tar.gz
busybox-032bf6553346537cb02d0406c05548c8aa23c81f.tar.bz2
diff: defeat gcc's optimization
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--editors/diff.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/editors/diff.c b/editors/diff.c
index af6917a..b89bbc1 100644
--- a/editors/diff.c
+++ b/editors/diff.c
@@ -435,7 +435,10 @@ static int *create_J(FILE_and_pos_t ft[2], int nlen[2], off_t *ix[2])
tok = read_token(&ft[i], tok);
if (!(tok & TOK_EMPTY)) {
/* Hash algorithm taken from Robert Sedgewick, Algorithms in C, 3d ed., p 578. */
- hash = hash * 128 - hash + TOK2CHAR(tok);
+ /*hash = hash * 128 - hash + TOK2CHAR(tok);
+ * gcc insists on optimizing above to "hash * 127 + ...", thus... */
+ unsigned o = hash - TOK2CHAR(tok);
+ hash = hash * 128 - o; /* we want SPEED here */
continue;
}
if (nlen[i]++ == sz) {