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16-Nov-2009 |
Bill Buzbee <buzbee@google.com> |
Jit: string's compareTo performance improvement.
Changed compareTo handler to call __memcmp16() for strings >= 32 chars.
However, even for those strings, the first two chars are done in the
handler (to catch early-out cases).
Comparisons were done with micro-benchmarks comparing 10 and 200-char
strings.
The strings were:
equal -> Q
not equal at start -> S
not equal at end -> E
The test configurations were handler (H) [the previous handler], subroutine (S)
[memcmp16()} and blended (B) [this commit]
H S B
10E 60 138 65
10S 32 70 30
10Q 9 9 9
100E 745 708 716
In short, the small string cases were twice as fast with the existing
handler compared to memcmp16, but memcmp16 was ~5% faster for long
strings.
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