From: Alexander Monakov <amonakov@ispras•ru>
To: git@vger•kernel.org
Cc: Alexander Monakov <amonakov@ispras•ru>,
Phillip Wood <phillip.wood@dunelm•org.uk>
Subject: [PATCH v2 1/4] xdiff: refactor xdl_hash_record()
Date: Mon, 8 Sep 2025 21:49:36 +0300 [thread overview]
Message-ID: <20250908184939.16338-1-amonakov@ispras.ru> (raw)
From: Phillip Wood <phillip.wood@dunelm•org.uk>
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>
---
xdiff/xutils.c | 7 ++-----
xdiff/xutils.h | 10 +++++++++-
2 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index 444a108f87..e070ed649f 100644
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -249,7 +249,7 @@ int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
return 1;
}
-static unsigned long xdl_hash_record_with_whitespace(char const **data,
+unsigned long xdl_hash_record_with_whitespace(char const **data,
char const *top, long flags) {
unsigned long ha = 5381;
char const *ptr = *data;
@@ -294,13 +294,10 @@ static unsigned long xdl_hash_record_with_whitespace(char const **data,
return ha;
}
-unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
+unsigned long xdl_hash_record_verbatim(char const **data, char const *top) {
unsigned long ha = 5381;
char const *ptr = *data;
- if (flags & XDF_WHITESPACE_FLAGS)
- return xdl_hash_record_with_whitespace(data, top, flags);
-
for (; ptr < top && *ptr != '\n'; ptr++) {
ha += (ha << 5);
ha ^= (unsigned long) *ptr;
diff --git a/xdiff/xutils.h b/xdiff/xutils.h
index fd0bba94e8..13f6831047 100644
--- a/xdiff/xutils.h
+++ b/xdiff/xutils.h
@@ -34,7 +34,15 @@ void *xdl_cha_alloc(chastore_t *cha);
long xdl_guess_lines(mmfile_t *mf, long sample);
int xdl_blankline(const char *line, long size, long flags);
int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags);
-unsigned long xdl_hash_record(char const **data, char const *top, long flags);
+unsigned long xdl_hash_record_verbatim(char const **data, char const *top);
+unsigned long xdl_hash_record_with_whitespace(char const **data, char const *top, long flags);
+static inline unsigned long xdl_hash_record(char const **data, char const *top, long flags)
+{
+ if (flags & XDF_WHITESPACE_FLAGS)
+ return xdl_hash_record_with_whitespace(data, top, flags);
+ else
+ return xdl_hash_record_verbatim(data, top);
+}
unsigned int xdl_hashbits(unsigned int size);
int xdl_num_out(char *out, long val);
int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
--
2.49.1
next reply other threads:[~2025-09-08 18:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-08 18:49 Alexander Monakov [this message]
2025-09-08 18:49 ` [PATCH v2 2/4] xdiff: annotate unlikely branch Alexander Monakov
2025-09-08 18:49 ` [PATCH v2 3/4] xdiff: move hashing functions to a separate header Alexander Monakov
2025-09-08 18:49 ` [PATCH v2 4/4] xdiff: use a faster hash in xdl_hash_record_verbatim Alexander Monakov
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