1587738 - [BinAST] Add a cache for MultiLookupHuffmanTable

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[David Teller [:Yoric] - still alive but not very active]

In each MultiLookupHuffmanTable, we know that the values used most often are the ones with the shortest paths. We could add a cache of these values in MultiLookupHuffmanTable to cut on the time spent resolving these most commonly used values.

Comment 1

[David Teller [:Yoric] - still alive but not very active]

Attachment: Bug 1587738 - Adding a fastpath for the most common prefixes of a `MultiLookupHuffmanTable`;r?arai

By definition of Huffman encoding, the shortest keys are reserved for the most common values.
This patch changes how we store these shortest keys in a MultiLookupHuffmanTable to
improve lookup speed: instead of storing short keys in a subtable by extending them,
we store them in a SingleLookupHuffmanTable.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ded00ff91429
Adding a fastpath for the most common prefixes of a `MultiLookupHuffmanTable`;r=arai

Comment 3

[Dorel Luca [:dluca]]

Backed out 2 changesets (bug 1587738, bug 1588051) for build bustage on js/src/jsapi-tests/testBinASTReader.cpp. CLOSED TREE

Log:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=271301088&repo=autoland&lineNumber=43974

Push with failures:
https://treeherder.mozilla.org/#/jobs?repo=autoland&revision=0c632655907932ee1559cd09aa2b264c461e2b3b

Backout:
https://hg.mozilla.org/integration/autoland/rev/29f82221b2158aa65fd6e289d5111598fa7b2544

Comment 4

[David Teller [:Yoric] - still alive but not very active]

Sorry, typo in the other bug. Should be able to reland.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/58fc2e7b4956
Adding a fastpath for the most common prefixes of a `MultiLookupHuffmanTable`;r=arai

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/58fc2e7b4956