Darwin does not define __WORDSIZE, and compiles the 32-bit code path
on 64-bit systems, resulting in a totally broken git.
I could not find an alternative -- other than the platform symbols
(__x86_64__ etc.) -- that does the test in the preprocessor. However,
we can also just test for the size of a 'long', which is what really
matters here. Any compiler worth its salt will leave only the branch
relevant for its platform, and indeed on Linux/GCC the numbers don't
change:
Test tr/darwin-xdl-fast-hash origin/next origin/master
------------------------------------------------------------------------------------------------------------------
4000.1: log -3000 (baseline) 0.09(0.07+0.01) 0.09(0.07+0.01) -5.5%* 0.09(0.07+0.01) -4.1%
4000.2: log --raw -3000 (tree-only) 0.47(0.41+0.05) 0.47(0.40+0.05) -0.5% 0.45(0.38+0.06) -3.5%.
4000.3: log -p -3000 (Myers) 1.81(1.67+0.12) 1.81(1.67+0.13) +0.3% 1.99(1.84+0.12) +10.2%***
4000.4: log -p -3000 --histogram 1.79(1.66+0.11) 1.80(1.67+0.11) +0.4% 1.96(1.82+0.10) +9.2%***
4000.5: log -p -3000 --patience 2.17(2.02+0.13) 2.20(2.04+0.13) +1.3%. 2.33(2.18+0.13) +7.4%***
------------------------------------------------------------------------------------------------------------------
Significance hints: '.' 0.1 '*' 0.05 '**' 0.01 '***' 0.001
Signed-off-by: Thomas Rast <trast@xxxxxxxxxxxxxxx>
---
Incidentally, on the OS X machine I have access to, the difference is
even bigger, something like 14% for 'log -p -3000'. I'm too lazy to
work out the exact numbers since the perf code doesn't work there.
xdiff/xutils.c | 52 +++++++++++++++++++++++-----------------------------
1 file changed, 23 insertions(+), 29 deletions(-)
diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index e05b5c9..1b3b471 100644
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -290,39 +290,33 @@ static inline unsigned long has_zero(unsigned long a)
return ((a - ONEBYTES) & ~a) & HIGHBITS;
}
-#if __WORDSIZE == 64
-
-/*
- * Jan Achrenius on G+: microoptimized version of
- * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
- * that works for the bytemasks without having to
- * mask them first.
- */
static inline long count_masked_bytes(unsigned long mask)
{
- return mask * 0x0001020304050608 >> 56;
-}
-
-#else /* 32-bit case */
-
-/* Modified Carl Chatfield G+ version for 32-bit */
-static inline long count_masked_bytes(long mask)
-{
- /*
- * (a) gives us
- * -1 (0, ff), 0 (ffff) or 1 (ffffff)
- * (b) gives us
- * 0 for 0, 1 for (ff ffff ffffff)
- * (a+b+1) gives us
- * correct 0-3 bytemask count result
- */
- long a = (mask - 256) >> 23;
- long b = mask & 1;
- return a + b + 1;
+ if (sizeof(long) == 8) {
+ /*
+ * Jan Achrenius on G+: microoptimized version of
+ * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
+ * that works for the bytemasks without having to
+ * mask them first.
+ */
+ return mask * 0x0001020304050608 >> 56;
+ } else {
+ /*
+ * Modified Carl Chatfield G+ version for 32-bit *
+ *
+ * (a) gives us
+ * -1 (0, ff), 0 (ffff) or 1 (ffffff)
+ * (b) gives us
+ * 0 for 0, 1 for (ff ffff ffffff)
+ * (a+b+1) gives us
+ * correct 0-3 bytemask count result
+ */
+ long a = (mask - 256) >> 23;
+ long b = mask & 1;
+ return a + b + 1;
+ }
}
-#endif
-
unsigned long xdl_hash_record(char const **data, char const *top, long flags)
{
unsigned long hash = 5381;
--
1.7.10.512.g5bfc6
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