599254 - Avoid an unnecessary switch in the JSON parser

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Nicholas Nethercote [inactive]]

Attachment: patch (against TM 54303:52c66b17843e)

This patch replaces HandleData() with four more specific functions.  This
avoids the unnecessary switching.  It reduces the instruction count on
Kraken's json-parse-financial from 724.7M to 710.0M, and gains maybe 5ms or
so out of 168ms on my Linux box.  A small win, but also an easy one.

Comment 1

[Nicholas Nethercote [inactive]]

http://hg.mozilla.org/tracemonkey/rev/5bd0b374d87b

Comment 2

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/5bd0b374d87b

Comment 3

[Mozilla RelEng Bot]

A changeset from this bug was associated with a XP Ts, Cold MED Dirty Profile regression on Firefox. boo-urns :(

  Previous: avg 420.356 stddev 3.679 of 30 runs up to a9d1ad0bc386
  New     : avg 430.832 stddev 1.905 of 5 runs since a60414d076b5
  Change  : +10.475 (2.49% / z=2.847)
  Graph   : http://mzl.la/bZFaB3

The regression occurred from changesets in the following range:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a9d1ad0bc386&tochange=a60414d076b5

The tag [suspect-regress-ts_cold_generated_med] has been added to the status whiteboard;
please remove it only once you have confirmed this bug is not the cause
of the regression.

Comment 4

[Mozilla RelEng Bot]

A changeset from this bug was associated with a Win7 Dromaeo (CSS) regression on Firefox. boo-urns :(

  Previous: avg 2014.419 stddev 40.480 of 30 runs up to a9d1ad0bc386
  New     : avg 1901.610 stddev 12.432 of 5 runs since a60414d076b5
  Change  : -112.809 (-5.6% / z=2.787)
  Graph   : http://mzl.la/9gFu4n

The regression occurred from changesets in the following range:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a9d1ad0bc386&tochange=a60414d076b5

The tag [suspect-regress-dromaeo_css] has been added to the status whiteboard;
please remove it only once you have confirmed this bug is not the cause
of the regression.

Comment 5

[Mozilla RelEng Bot]

A changeset from this bug was associated with a Win7 Dromaeo (jslib) regression on Firefox. boo-urns :(

  Previous: avg 127.610 stddev 4.222 of 30 runs up to a9d1ad0bc386
  New     : avg 116.384 stddev 0.751 of 5 runs since a60414d076b5
  Change  : -11.226 (-8.8% / z=2.659)
  Graph   : http://mzl.la/bZu5UP

The regression occurred from changesets in the following range:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a9d1ad0bc386&tochange=a60414d076b5

The tag [suspect-regress-dromaeo_jslib] has been added to the status whiteboard;
please remove it only once you have confirmed this bug is not the cause
of the regression.

Comment 6

[Mozilla RelEng Bot]

A changeset from this bug was associated with a XP Dromaeo (CSS) regression on Firefox. boo-urns :(

  Previous: avg 2045.275 stddev 49.676 of 30 runs up to a9d1ad0bc386
  New     : avg 1936.120 stddev 13.937 of 5 runs since a60414d076b5
  Change  : -109.155 (-5.34% / z=2.197)
  Graph   : http://mzl.la/b0dlou

The regression occurred from changesets in the following range:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a9d1ad0bc386&tochange=a60414d076b5

The tag [suspect-regress-dromaeo_css] has been added to the status whiteboard;
please remove it only once you have confirmed this bug is not the cause
of the regression.

Comment 7

[Mozilla RelEng Bot]

A changeset from this bug was associated with a XP Dromaeo (jslib) regression on Firefox. boo-urns :(

  Previous: avg 129.703 stddev 4.099 of 30 runs up to a9d1ad0bc386
  New     : avg 117.954 stddev 0.660 of 5 runs since a60414d076b5
  Change  : -11.749 (-9.06% / z=2.866)
  Graph   : http://mzl.la/avZij4

The regression occurred from changesets in the following range:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a9d1ad0bc386&tochange=a60414d076b5

The tag [suspect-regress-dromaeo_jslib] has been added to the status whiteboard;
please remove it only once you have confirmed this bug is not the cause
of the regression.