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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
- From: Paul Eggert <eggert at CS dot UCLA dot EDU>
- To: autoconf-patches at gnu dot org, bug-gnulib at gnu dot org, gcc at gcc dot gnu dot org
- Date: Sun, 31 Dec 2006 17:21:26 -0800
- Subject: Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
- References: <200612300047.kBU0lFwk014817@localhost.localdomain> <871wmht4ab.fsf@penguin.cs.ucla.edu> <10612302258.AA24598@vlsi1.ultra.nyu.edu> <87lkkosz1n.fsf@penguin.cs.ucla.edu> <45970416.80407@adacore.com> <8764bssikm.fsf@penguin.cs.ucla.edu> <571f6b510612310047r3b7ef9acl4a0ab082e88e17a3@mail.gmail.com> <87bqlkmm3r.fsf@penguin.cs.ucla.edu> <4aca3dc20612310641n78e8898euf1c003444e2303eb@mail.gmail.com> <84fc9c000612310645h67066c70vf9eb11af74b639a7@mail.gmail.com> <4aca3dc20612311613r2992db50o851c7d73603b42ef@mail.gmail.com>
"Daniel Berlin" <dberlin@dberlin.org> writes:
>> http://www.suse.de/~gcctest/SPEC/CFP/sb-vangelis-head-64/recent.html
>> and
>> http://www.suse.de/~gcctest/SPEC/CINT/sb-vangelis-head-64/recent.html
>>
> Note the distinct drop in performance across almost all the benchmarks
> on Dec 30, including popular programs like bzip2 and gzip.
That benchmark isn't that relevant, as it's using -O3, as is typical
for SPEC benchmarks.
This discussion is talking about -O2, not -O3. The proposed change
(i.e., having -O2 imply -fwrapv) would not affect -O3 benchmark
scores.