Bug 105239 - DFG is too aggressive eliding overflow checks for additions involving large constants
Summary: DFG is too aggressive eliding overflow checks for additions involving large c...
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:
 
Reported: 2012-12-17 18:32 PST by Filip Pizlo
Modified: 2012-12-17 20:36 PST (History)
8 users (show)

See Also:

Attachments
the patch (18.74 KB, patch)
2012-12-17 18:34 PST, Filip Pizlo 		barraclough: review+
webkit-ews: commit-queue-
Details | Formatted Diff | Diff
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Description Filip Pizlo 2012-12-17 18:32:05 PST 
It's cool to elide the overflow check on:

a + 5432645326542

but it's not cool to elide all checks on:

a + 654365375437 + 5432645326542

because the combined overflow might lead to bad results.

Disclaimer: the above constants were created by randomly tapping the keyboard.  The bug actually occurs when you have constants close to 2^48.
Comment 1 Filip Pizlo 2012-12-17 18:34:00 PST 
Created attachment 179850 [details]
the patch
Comment 2 Early Warning System Bot 2012-12-17 18:45:17 PST 
Comment on attachment 179850 [details]
the patch

Attachment 179850 [details] did not pass qt-ews (qt):
Output: http://queues.webkit.org/results/15375929
Comment 3 Early Warning System Bot 2012-12-17 18:47:44 PST 
Comment on attachment 179850 [details]
the patch

Attachment 179850 [details] did not pass qt-wk2-ews (qt):
Output: http://queues.webkit.org/results/15371959
Comment 4 Filip Pizlo 2012-12-17 20:36:45 PST 
Landed in http://trac.webkit.org/changeset/137980