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strings: add asm version of Index() for short strings on amd64

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Currently we have special case for 1-byte strings,
This extends this to strings shorter than 32 bytes on amd64.
Results (broadwell):

name                 old time/op  new time/op  delta
IndexRune-4          57.4ns ± 0%  57.5ns ± 0%   +0.10%        (p=0.000 n=20+19)
IndexRuneFastPath-4  20.4ns ± 0%  20.4ns ± 0%     ~     (all samples are equal)
Index-4              21.0ns ± 0%  21.8ns ± 0%   +3.81%        (p=0.000 n=20+20)
LastIndex-4          7.07ns ± 1%  6.98ns ± 0%   -1.21%        (p=0.000 n=20+16)
IndexByte-4          18.3ns ± 0%  18.3ns ± 0%     ~     (all samples are equal)
IndexHard1-4         1.46ms ± 0%  0.39ms ± 0%  -73.06%        (p=0.000 n=16+16)
IndexHard2-4         1.46ms ± 0%  0.30ms ± 0%  -79.55%        (p=0.000 n=18+18)
IndexHard3-4         1.46ms ± 0%  0.66ms ± 0%  -54.68%        (p=0.000 n=19+19)
LastIndexHard1-4     1.46ms ± 0%  1.46ms ± 0%   -0.01%        (p=0.036 n=18+20)
LastIndexHard2-4     1.46ms ± 0%  1.46ms ± 0%     ~           (p=0.588 n=19+19)
LastIndexHard3-4     1.46ms ± 0%  1.46ms ± 0%     ~           (p=0.283 n=17+20)
IndexTorture-4       11.1µs ± 0%  11.1µs ± 0%   +0.01%        (p=0.000 n=18+17)

Change-Id: I892781549f558f698be4e41f9f568e3d0611efb5
Reviewed-on: https://go-review.googlesource.com/16430
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
This commit is contained in:
Ilya Tocar 2015-10-28 18:05:05 +03:00 • committed by Keith Randall
parent 1870572180
commit 95333aea53
5 changed files with 311 additions and 37 deletions
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53
src/strings/strings_test.go
View file

@ -59,6 +59,59 @@ var indexTests = []IndexTest{
{"abc", "b", 1},
{"abc", "c", 2},
{"abc", "x", -1},
// test special cases in Index() for short strings
{"", "ab", -1},
{"bc", "ab", -1},
{"ab", "ab", 0},
{"xab", "ab", 1},
{"xab"[:2], "ab", -1},
{"", "abc", -1},
{"xbc", "abc", -1},
{"abc", "abc", 0},
{"xabc", "abc", 1},
{"xabc"[:3], "abc", -1},
{"xabxc", "abc", -1},
{"", "abcd", -1},
{"xbcd", "abcd", -1},
{"abcd", "abcd", 0},
{"xabcd", "abcd", 1},
{"xyabcd"[:5], "abcd", -1},
{"xbcqq", "abcqq", -1},
{"abcqq", "abcqq", 0},
{"xabcqq", "abcqq", 1},
{"xyabcqq"[:6], "abcqq", -1},
{"xabxcqq", "abcqq", -1},
{"xabcqxq", "abcqq", -1},
{"", "01234567", -1},
{"32145678", "01234567", -1},
{"01234567", "01234567", 0},
{"x01234567", "01234567", 1},
{"xx01234567"[:9], "01234567", -1},
{"", "0123456789", -1},
{"3214567844", "0123456789", -1},
{"0123456789", "0123456789", 0},
{"x0123456789", "0123456789", 1},
{"xyz0123456789"[:12], "0123456789", -1},
{"x01234567x89", "0123456789", -1},
{"", "0123456789012345", -1},
{"3214567889012345", "0123456789012345", -1},
{"0123456789012345", "0123456789012345", 0},
{"x0123456789012345", "0123456789012345", 1},
{"", "01234567890123456789", -1},
{"32145678890123456789", "01234567890123456789", -1},
{"01234567890123456789", "01234567890123456789", 0},
{"x01234567890123456789", "01234567890123456789", 1},
{"xyz01234567890123456789"[:22], "01234567890123456789", -1},
{"", "0123456789012345678901234567890", -1},
{"321456788901234567890123456789012345678911", "0123456789012345678901234567890", -1},
{"0123456789012345678901234567890", "0123456789012345678901234567890", 0},
{"x0123456789012345678901234567890", "0123456789012345678901234567890", 1},
{"xyz0123456789012345678901234567890"[:33], "0123456789012345678901234567890", -1},
{"", "01234567890123456789012345678901", -1},
{"32145678890123456789012345678901234567890211", "01234567890123456789012345678901", -1},
{"01234567890123456789012345678901", "01234567890123456789012345678901", 0},
{"x01234567890123456789012345678901", "01234567890123456789012345678901", 1},
{"xyz01234567890123456789012345678901"[:34], "01234567890123456789012345678901", -1},
}
var lastIndexTests = []IndexTest{