path: root/src/multibyte
diff options
authorRich Felker <>2013-04-08 22:49:59 -0400
committerRich Felker <>2013-04-08 22:49:59 -0400
commita49e038bab7b3927b6a9c7d0c52f9e1a9cb82629 (patch)
tree4d4f8a1686d8db7588efed0d7f03968e76d5294e /src/multibyte
parent8f06ab0eb9c22998a47803938588bb0b13092a0b (diff)
optimize mbrtowc
this simple change, in my measurements, makes about a 7% performance improvement. at first glance this change would seem like a compiler-specific hack, since the modified code is not even used. however, I suspect the reason is that I'm eliminating a second path into the main body of the code, allowing the compiler more flexibility to optimize the normal (hot) path into the main body. so even if it weren't for the measurable (and quite notable) difference in performance, I think the change makes sense.
Diffstat (limited to 'src/multibyte')
1 files changed, 2 insertions, 3 deletions
diff --git a/src/multibyte/mbrtowc.c b/src/multibyte/mbrtowc.c
index cc497810..ec323859 100644
--- a/src/multibyte/mbrtowc.c
+++ b/src/multibyte/mbrtowc.c
@@ -22,9 +22,8 @@ size_t mbrtowc(wchar_t *restrict wc, const char *restrict src, size_t n, mbstate
c = *(unsigned *)st;
if (!s) {
- s = (void *)"";
- wc = (void *)&wc;
- n = 1;
+ if (c) goto ilseq;
+ return 0;
} else if (!wc) wc = (void *)&wc;
if (!n) return -2;