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Re: clang vs free software
- From: Xinliang David Li <davidxl at google dot com>
- To: Chris Lattner <clattner at apple dot com>
- Cc: Steven Bosscher <stevenb dot gcc at gmail dot com>, esr at thyrsus dot com, Helmut Eller <eller dot helmut at gmail dot com>, rms at gnu dot org, GCC Mailing List <gcc at gcc dot gnu dot org>
- Date: Thu, 23 Jan 2014 15:04:59 -0800
- Subject: Re: clang vs free software
- Authentication-results: sourceware.org; auth=none
- References: <CAJnXXoi2MLpZWxOxknR=mNR91JdZcHrKRsqYZSWY373fvwxObg at mail dot gmail dot com> <87eh439w1n dot fsf at uwakimon dot sk dot tsukuba dot ac dot jp> <CAJnXXojjSAWL8cqZp0X16xa81R73huywtTS90p6O3CpRaPOiDQ at mail dot gmail dot com> <jwvwqhu8zcg dot fsf-monnier+emacs at gnu dot org> <87ha8yqvup dot fsf at engster dot org> <E1W5cXI-0000j4-8x at fencepost dot gnu dot org> <CAJnXXoiuzZhjDGpvXY7psee=+bXn1rB+GdELYP0FS0CuWPqYeQ at mail dot gmail dot com> <E1W6HwP-0001WU-Tg at fencepost dot gnu dot org> <87r47zezcc dot fsf at fencepost dot gnu dot org> <m2eh3ykc3y dot fsf at gmail dot com> <20140123174934 dot GA10933 at thyrsus dot com> <CABu31nMSPdsGU-sAcO_HnFRetqQDgk5fQ3R12aYA0aqTvgdx+A at mail dot gmail dot com> <8E23EFFC-88C3-48BE-97AB-77207DA32499 at apple dot com>
On Thu, Jan 23, 2014 at 2:56 PM, Chris Lattner <email@example.com> wrote:
> On Jan 23, 2014, at 12:14 PM, Steven Bosscher <firstname.lastname@example.org> wrote:
>> (Hint: read http://vmakarov.fedorapeople.org/spec/ as an example of a
>> better-supported point of view.)
> Unrelated to this thread, it would be great for this web page to get updated. You may find it to be "a better-supported point of view", but it is also comparing against clang 3.2, which is from the end of 2012, and a lot has changed since then.
> Modern clang versions have its autovectorizor on by default (like GCC's) and generate much better code in general.
Correction -- unlike LLVM, autovectorizer is not turned on by default
at O2 for GCC yet.
> http://www.phoronix.com/ has done some benchmarks across a wider range of code than just spec (which is notoriously "hacked" by compiler developers) and Clang generates better code (and faster) than GCC in many cases.