Bug 158142

Summary: Bogus uses of regexp matching should realize that they will OOM before they start swapping
Product: WebKit Reporter: Filip Pizlo <fpizlo>
Component: JavaScriptCoreAssignee: Filip Pizlo <fpizlo>
Status: RESOLVED FIXED    
Severity: Normal CC: commit-queue, ggaren, msaboff, saam
Priority: P2    
Version: WebKit Nightly Build   
Hardware: All   
OS: All   
Attachments:
Description Flags
it does something
none
the patch
msaboff: review+
performance none

Filip Pizlo
Reported 2016-05-26 19:20:59 PDT
Patch forthcoming.
Attachments
it does something (13.65 KB, patch)
2016-05-26 19:22 PDT, Filip Pizlo 		no flags
DetailsFormatted DiffDiff
the patch (16.92 KB, patch)
2016-05-26 20:53 PDT, Filip Pizlo 		msaboff: review+
DetailsFormatted DiffDiff
performance (77.39 KB, text/plain)
2016-05-27 07:25 PDT, Filip Pizlo 		no flags
Details
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Filip Pizlo
Comment 1 2016-05-26 19:22:45 PDT
Created attachment 279936 [details] it does something The intuition is that the individual regexp matches are not really observable, so if we detect trouble, we can just do a dry run to see how bad things get before we start allocating tons of memory. On my test case (from jsfunfuzz), this reduces the runtime by >10x and reduces memory usage by ~8x and eliminates swapping. Hooray.
Filip Pizlo
Comment 2 2016-05-26 20:53:25 PDT
Created attachment 279943 [details] the patch
WebKit Commit Bot
Comment 3 2016-05-26 20:56:11 PDT
Attachment 279943 [details] did not pass style-queue: ERROR: Source/JavaScriptCore/runtime/RegExpObject.cpp:183: Place brace on its own line for function definitions. [whitespace/braces] [4] ERROR: Source/JavaScriptCore/runtime/RegExpObject.cpp:220: Semicolon defining empty statement for this loop. Use { } instead. [whitespace/semicolon] [5] Total errors found: 2 in 8 files If any of these errors are false positives, please file a bug against check-webkit-style.
Filip Pizlo
Comment 4 2016-05-27 07:25:13 PDT
Created attachment 279958 [details] performance Looks neutral on the major benchmarks.
Michael Saboff
Comment 5 2016-05-27 07:42:53 PDT
Comment on attachment 279943 [details] the patch r=me Please add a test that goes into the dry run code but still succeeds.
Filip Pizlo
Comment 6 2016-05-27 07:58:57 PDT
Landed in http://trac.webkit.org/changeset/201451
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