Bug 133935 - [ftlopt] DFG OSR entry should have a crystal-clear story for when it's safe to enter at a block with a set of values
Summary: [ftlopt] DFG OSR entry should have a crystal-clear story for when it's safe t...
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: JavaScriptCore (show other bugs)
Version: 528+ (Nightly build)
Hardware: All All
: P2 Normal
Assignee: Filip Pizlo
URL:
Keywords:
Depends on:
Blocks: 133918
  Show dependency tree / graph
 
Reported: 2014-06-15 22:06 PDT by Filip Pizlo
Modified: 2014-06-16 11:06 PDT (History)
7 users (show)

See Also:

Attachments
the patch (15.63 KB, patch)
2014-06-15 22:09 PDT, Filip Pizlo 		oliver: review+
Details | Formatted Diff | Diff
View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Filip Pizlo 2014-06-15 22:06:42 PDT 
Currently we record the abstract values at the head of a block at the time that the backend runs.  This causes weirdness if a subsequent run of the CFA proves less things (or different things) than a past run, and we had already performed optimizations based on the past run.

The solution is to save the intersection of all proofs.

This makes constant folding a lot easier to reason about.
Comment 1 Filip Pizlo 2014-06-15 22:09:19 PDT 
Created attachment 233151 [details]
the patch
Comment 2 Filip Pizlo 2014-06-16 11:06:51 PDT 
Landed in http://trac.webkit.org/changeset/170016