@matheusbsbs / matheus-bagliano / commits / 41d97837ab

xdiff: refactor xdl_hash_record()

Inline the check for whitespace flags so that the compiler can hoist it out of the loop in xdl_prepare_ctx(). This improves the performance by 8%. $ hyperfine --warmup=1 -L rev HEAD,HEAD^ --setup='git checkout {rev} -- :/ && make git' ': {rev}; GIT_CONFIG_GLOBAL=/dev/null ./git log --oneline --shortstat v2.0.0..v2.5.0' Benchmark 1: : HEAD; GIT_CONFIG_GLOBAL=/dev/null ./git log --oneline --shortstat v2.0.0..v2.5.0 Time (mean ± σ): 1.670 s ± 0.044 s [User: 1.473 s, System: 0.196 s] Range (min … max): 1.619 s … 1.754 s 10 runs Benchmark 2: : HEAD^; GIT_CONFIG_GLOBAL=/dev/null ./git log --oneline --shortstat v2.0.0..v2.5.0 Time (mean ± σ): 1.801 s ± 0.021 s [User: 1.605 s, System: 0.192 s] Range (min … max): 1.766 s … 1.831 s 10 runs Summary ': HEAD^; GIT_CONFIG_GLOBAL=/dev/null ./git log --oneline --shortstat v2.0.0..v2.5.0' ran 1.08 ± 0.03 times faster than ': HEAD^^; GIT_CONFIG_GLOBAL=/dev/null ./git log --oneline --shortstat v2.0.0..v2.5.0' Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Phillip Wood committed Jul 28, 2025 at 22:05 UTC 41d97837ab1e5a35fdcfd7f6af9b5d56af62e92a

2 files changed +11 -6

xdiff/xutils.c

+2 -5

@@ -249,7 +249,7 @@ int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)

249 return 1;

250 }

251

252 -static unsigned long xdl_hash_record_with_whitespace(char const **data,

252 +unsigned long xdl_hash_record_with_whitespace(char const **data,

253 char const *top, long flags) {

254 unsigned long ha = 5381;

255 char const *ptr = *data;

@@ -294,13 +294,10 @@ static unsigned long xdl_hash_record_with_whitespace(char const **data,

294 return ha;

295 }

296

297 -unsigned long xdl_hash_record(char const **data, char const *top, long flags) {

297 +unsigned long xdl_hash_record_verbatim(char const **data, char const *top) {

298 unsigned long ha = 5381;

299 char const *ptr = *data;

300

301 - if (flags & XDF_WHITESPACE_FLAGS)

302 - return xdl_hash_record_with_whitespace(data, top, flags);

303 -

301 for (; ptr < top && *ptr != '\n'; ptr++) {

302 ha += (ha << 5);

303 ha ^= (unsigned long) *ptr;

xdiff/xutils.h

+9 -1

@@ -34,7 +34,15 @@ void *xdl_cha_alloc(chastore_t *cha);

34 long xdl_guess_lines(mmfile_t *mf, long sample);

35 int xdl_blankline(const char *line, long size, long flags);

36 int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags);

37 -unsigned long xdl_hash_record(char const **data, char const *top, long flags);

37 +unsigned long xdl_hash_record_verbatim(char const **data, char const *top);

38 +unsigned long xdl_hash_record_with_whitespace(char const **data, char const *top, long flags);

39 +static inline unsigned long xdl_hash_record(char const **data, char const *top, long flags)

40 +{

41 + if (flags & XDF_WHITESPACE_FLAGS)

42 + return xdl_hash_record_with_whitespace(data, top, flags);

43 + else

44 + return xdl_hash_record_verbatim(data, top);

45 +}

46 unsigned int xdl_hashbits(unsigned int size);

47 int xdl_num_out(char *out, long val);

48 int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,