Issue 2349 in v8: eliminate HTransitionElementsKind dominated by HCheckMaps with a different map set

[codesite...@google.com]

Status: Accepted
Owner: ----
CC: da...@chromium.org, verwa...@chromium.org
Labels: Type-Bug Priority-Medium

New issue 2349 by veg...@chromium.org: eliminate HTransitionElementsKind
dominated by HCheckMaps with a different map set
http://code.google.com/p/v8/issues/detail?id=2349

I was looking at register allocation in kraken-audio-beat-detection and
noticed that in the innermost loop there is a HTransitionElementsKind that
is dominated by a map check that actually allows to prove that that
transition can never happen.

I tried writing a simple pass to eliminate transition and it seems to
improve perf by ~15%.

Attachments:
transitions-eliminator.patch 3.6 KB

[codesite...@google.com]

Updates:
Owner: verwa...@chromium.org

Comment #1 on issue 2349 by da...@chromium.org: eliminate

HTransitionElementsKind dominated by HCheckMaps with a different map set
http://code.google.com/p/v8/issues/detail?id=2349

(No comment was entered for this change.)

[codesite...@google.com]

Comment #2 on issue 2349 by verwa...@chromium.org: eliminate

HTransitionElementsKind dominated by HCheckMaps with a different map set
http://code.google.com/p/v8/issues/detail?id=2349

Unfortunately with my elements transition CL in, it's reduced to ~1%; which
is overshadowed by the 4% regression on JsonParseFinancial:

http://70.32.156.88:8080/Comparison#targetA%3Dv8%3BmachineTypeA%3Dlinux-x64%3BrevisionA%3D12640%3BpatchA%3Dverwaest-opt_licm_slava%3BtargetB%3Dv8%3BmachineTypeB%3Dlinux-x64%3BrevisionB%3D12640%3BpatchB%3Dverwaest-opt_licm

[codesite...@google.com]

Updates:
Owner: mvstan...@chromium.org

Comment #3 on issue 2349 by mvstan...@chromium.org: eliminate

HTransitionElementsKind dominated by HCheckMaps with a different map set
http://code.google.com/p/v8/issues/detail?id=2349

I'll have a look.

--
You received this message because this project is configured to send all
issue notifications to this address.
You may adjust your notification preferences at:
https://code.google.com/hosting/settings