diff: defeat gcc's optimization

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/editors/diff.c b/editors/diff.c
index af6917a03..b89bbc1dc 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) {