513407 - NJ: fold out (x == y) ? x : y and (y == x) ? x : y

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Julian Seward [:jseward]]

As per bug 513160 comment #5, for v8-richards there's some silly
cmov stuff produced.  Folding it out in ExprFilter is easy and appears
to give an improvement of about 8% of v8-richards.  Not r? at this 
point pending further profiling runs on a quieter machine.

Comment 1

[Julian Seward [:jseward]]

Attachment: patch to remove silly cmov cases

I'm sure that the benefit of the patch is not so much that it
gets rid of the cmovs, but more that it helps other transformations
(CSE, and maybe constant folding) to do better.  I say that because
not only does the program go faster, the traces have fewer guards,
which means some of them must have been folded or CSEd away.

Comment 2

[Julian Seward [:jseward]]

Attachment: patch v2, formatting change only (--> house style)

v8:            1.009x as fast    18112.7ms +/- 0.4%   17952.8ms +/- 0.4%  sig..
 crypto:       1.024x as fast     1073.3ms +/- 1.1%    1047.7ms +/- 1.4%  sig..
 deltablue:    -                 11141.2ms +/- 0.5%   11152.3ms +/- 0.5% 
 earley-boyer: 1.009x as fast     2891.7ms +/- 0.3%    2866.3ms +/- 0.8%  sig..
 raytrace:     1.020x as fast     1891.5ms +/- 0.4%    1854.4ms +/- 0.5%  sig..
 richards:     1.080x as fast     1115.0ms +/- 0.2%    1032.2ms +/- 0.2%  sig..

Comment 3

[Andreas Gal :gal]

Comment on attachment 398172 [details] [diff] [review]
patch v2, formatting change only (--> house style)

Sorry for the delay.

Comment 4

[Nicholas Nethercote [inactive]]

http://hg.mozilla.org/tracemonkey/rev/546ce1cc66bd

Comment 5

[Blake Kaplan (:mrbkap) (inactive)]

http://hg.mozilla.org/mozilla-central/rev/546ce1cc66bd

Comment 6

[Robert Sayre]

http://hg.mozilla.org/releases/mozilla-1.9.2/rev/1d2244258194