Reland: Speedup stringsearch for two byte strings

Reland: Speedup stringsearch for two byte strings

Uses the lower byte with memchr which is
significantly faster than a naive compare

Performance difference with bench (http://hastebin.com/xuxexataso.js):

old                             new

single character                single character
Κ found at 922                  Κ found at 922
3324                            616
㎡ found at 13217               ㎡ found at 13217
42366                           4931
က found at 4096                 က found at 4096
13369                           9836
＀ found at 65280                ＀ found at 65280
207472                          36149
ﾥ found at 65445                ﾥ found at 65445
209344                          36666
  found at 8197                   found at 8197
26731                           11757
倂 found at 20482               倂 found at 20482
66071                           17193

linear search                   linear search
ΚΛ found at 922                 ΚΛ found at 922
4112                            504
㎡㎢ found at 13217             ㎡㎢ found at 13217
55105                           5119
ﾥﾦ found at 65445               ﾥﾦ found at 65445
268016                          35496

linear + bmh search             linear + bmh search
ΚΛΜΝΞΟΠΡ found at 922           ΚΛΜΝΞΟΠΡ found at 922
2897                            522
ﾥﾦﾧﾨﾩﾪﾫﾬ found at 65445         ﾥﾦﾧﾨﾩﾪﾫﾬ found at 65445
167687                          35283

BUG=

Committed: https://crrev.com/24d481165cfda1669c92c06c0a67348f3e4add91
Cr-Commit-Position: refs/heads/master@{#30597}

[skomski, 2015-09-04 17:34:00]

Patchset #2 (id:20001) has been deleted

[skomski, 2015-09-04 17:39:23]

Patchset #2 (id:40001) has been deleted

[skomski, 2015-09-04 17:52:57]

karl@skomski.com changed reviewers:
+ jkummerow@chromium.org

[skomski, 2015-09-04 18:08:10]

Is it possible to run the msan or fuzzer bot before landing the commit?

[Jakob Kummerow, 2015-09-04 18:29:04]

The CQ bit was checked by jkummerow@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-04 18:29:14]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1324453007/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1324453007/60001

[Jakob Kummerow, 2015-09-04 18:32:31]

Looks good.

You can run the fuzzer locally: make x64.debug && tools/fuzz-harness.sh
out/x64.debug/d8

We seem to have an MSan try bot, but the link to start a job on it disappeared
when I triggered the CQ dry run. Hopefully it'll reappear when the dry run's
finished.

[commit-bot: I haz the power, 2015-09-04 18:52:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-04 18:52:12]

Dry run: This issue passed the CQ dry run.

[Jakob Kummerow, 2015-09-04 19:57:02]

The CQ bit was checked by jkummerow@chromium.org

[Jakob Kummerow, 2015-09-04 19:57:02]

lgtm

[commit-bot: I haz the power, 2015-09-04 19:57:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1324453007/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1324453007/60001

[commit-bot: I haz the power, 2015-09-04 19:58:42]

Committed patchset #2 (id:60001)

[commit-bot: I haz the power, 2015-09-04 19:58:55]

Patchset 2 (id:??) landed as
https://crrev.com/24d481165cfda1669c92c06c0a67348f3e4add91
Cr-Commit-Position: refs/heads/master@{#30597}

[skomski, 2015-09-05 09:02:50]

Since it failed on mips should I revert the patchset or should I quickly submit
a review before monday?

[Michael Achenbach, 2015-09-05 10:20:06]

On 2015/09/05 09:02:50, skomski wrote:
> Since it failed on mips should I revert the patchset or should I quickly
submit
> a review before monday?

It's on big endian only. No revert needed. And no hurries.