[PATCH/RFC v1 1/6] symlinks.c: small cleanup and optimisation
- From
- Kjetil Barvik <barvik@broadpark.no>
- Date
- Jan 26, 2009, 21:17 UTC
- Message-ID
- <1233004637-15112-2-git-send-email-barvik@broadpark.no>
- In-Reply-To
- <1233004637-15112-1-git-send-email-barvik@broadpark.no>
Simplify the if-else test in longest_match_lstat_cache() such that we only have one simple if test. Instead of testing for 'i == cache.len' or 'i == len', we transform this to a common test for 'i == max_len'.
And to further optimise we use 'i >= max_len' instead of 'i == max_len', the reason is that it is now the exact opposite of one part inside the while-loop termination expression 'i < max_len && name[i] == cache.path[i]', and then the compiler can hopefully/probably reuse a test-result from it.
We do similar transformations inside the lstat_cache() and the invalidate_lstat_cache() functions.
The result is a little smaller text-size as shown below:
~/git/git $ size symlinks_??_*
text data bss dec hex filename
1282 0 4116 5398 1516 symlinks_O2_after.o
1378 0 4116 5494 1576 symlinks_O2_before.o
896 0 4116 5012 1394 symlinks_Os_after.o
902 0 4116 5018 139a symlinks_Os_before.o'O2' means that the file is compiled with 'gcc -O2', and similar 'Os' means that the file is compiled with 'gcc -Os' (gcc 4.3.2).
Signed-off-by: Kjetil Barvik <barvik@broadpark.no> --- symlinks.c | 25 +++++++++++++------------ 1 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/symlinks.c b/symlinks.c index f262b7c..81f490c 100644 --- a/symlinks.c +++ b/symlinks.c @@ -25,15 +25,16 @@ static inline int longest_match_lstat_cache(int len, const char *name, } i++; } - /* Is the cached path string a substring of 'name'? */ - if (i == cache.len && cache.len < len && name[cache.len] == '/') { - match_len_prev = match_len; - match_len = cache.len; - /* Is 'name' a substring of the cached path string? */ - } else if ((i == len && len < cache.len && cache.path[len] == '/') || - (i == len && len == cache.len)) { + /* + * Is the cached path string a substring of 'name', is 'name' + * a substring of the cached path string, or is 'name' and the + * cached path string the exact same string? + */ + if (i >= max_len && ((i < len && name[i] == '/') || + (i < cache.len && cache.path[i] == '/') || + (len == cache.len))) { match_len_prev = match_len; - match_len = len; + match_len = i; } *previous_slash = match_len_prev; return match_len; @@ -91,7 +92,7 @@ static int lstat_cache(int len, const char *name, match_len = last_slash = longest_match_lstat_cache(len, name, &previous_slash); match_flags = cache.flags & track_flags & (FL_NOENT|FL_SYMLINK); - if (match_flags && match_len == cache.len) + if (match_flags && match_len >= cache.len) return match_flags; /* * If we now have match_len > 0, we would know that @@ -102,7 +103,7 @@ static int lstat_cache(int len, const char *name, * we can return immediately. */ match_flags = track_flags & FL_DIR; - if (match_flags && len == match_len) + if (match_flags && match_len >= len) return match_flags; } @@ -153,7 +154,7 @@ static int lstat_cache(int len, const char *name, cache.path[last_slash] = '\0'; cache.len = last_slash; cache.flags = save_flags; - } else if (track_flags & FL_DIR && + } else if ((track_flags & FL_DIR) && last_slash_dir > 0 && last_slash_dir <= PATH_MAX) { /* * We have a separate test for the directory case, @@ -184,7 +185,7 @@ void invalidate_lstat_cache(int len, const char *name) int match_len, previous_slash; match_len = longest_match_lstat_cache(len, name, &previous_slash); - if (len == match_len) { + if (match_len >= len) { if ((cache.track_flags & FL_DIR) && previous_slash > 0) { cache.path[previous_slash] = '\0'; cache.len = previous_slash;
-- 1.6.1.349.g99fa5