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Re: [PATCH] powerpc: strstr optimization
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <munroesj at linux dot vnet dot ibm dot com>
- Cc: Rajalakshmi Srinivasaraghavan <raji at linux dot vnet dot ibm dot com>, Ondřej Bílka <neleai at seznam dot cz>, <libc-alpha at sourceware dot org>, <sjmunroe at us dot ibm dot com>
- Date: Mon, 11 May 2015 20:19:01 +0000
- Subject: Re: [PATCH] powerpc: strstr optimization
- Authentication-results: sourceware.org; auth=none
- References: <1429254584-124997-1-git-send-email-raji at linux dot vnet dot ibm dot com> <20150501120510 dot GB2203 at domone> <554704A1 dot 3010007 at linux dot vnet dot ibm dot com> <20150505211414 dot GA18085 at domone> <554A1703 dot 5090707 at linux dot vnet dot ibm dot com> <1431367848 dot 14012 dot 3 dot camel at sjmunroe-ThinkPad-W500>
On Mon, 11 May 2015, Steven Munroe wrote:
> I think we should move on with (commit) Raji's patch as is.
Does the patch avoid quadratic worst case? Quadratic performance in
strstr is an unambiguous regression, allowing for denial-of-service, that
should not be introduced on any platform (cf bug 12100). Indeed, gnulib
has a configure test for quadratic strstr, so if you introduce quadratic
worst case then the effect will be that all applications using gnulib
automatically configure themselves to use gnulib's strstr and not glibc's
at all.
--
Joseph S. Myers
joseph@codesourcery.com