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Date: Tue, 16 Mar 2004 13:31:00 -0000
From: Jakub Jelinek <jakub@redhat.com>
To: Joe Buck <Joe.Buck@synopsys.COM>
Cc: James Morrison <ja2morri@csclub.uwaterloo.ca>,
   Roger Sayle <roger@eyesopen.com>,
   Scott Robert Ladd <coyote@coyotegulch.com>, gcc@gcc.gnu.org
Subject: Re: GCC viciously beaten by ICC in trig test!
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Reply-To: Jakub Jelinek <jakub@redhat.com>
References: <Pine.LNX.4.44.0403141713460.12909-100000@www.eyesopen.com> <kfhllm21yj0.fsf@perpugilliam.csclub.uwaterloo.ca> <20040315061104.GR3822@sunsite.ms.mff.cuni.cz> <20040315101313.A4286@synopsys.com>
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On Mon, Mar 15, 2004 at 10:13:13AM -0800, Joe Buck wrote:
> On Mon, Mar 15, 2004 at 07:11:04AM +0100, Jakub Jelinek wrote:
> > Well, the inlines shouldn't be removed, but guarded with
> > # if !__GNUC_PREREQ (MAJOR,MINOR)
> > ...
> > # endif
> > where MAJOR, MINOR is the first __GNUC__ and __GNUC_MINOR__ of GCC which
> > can handle all cases the same or better than the glibc inline.
> 
> Is the proper requirement "all cases"?  What if the glibc inline is
> sometimes better, but sometimes far worse?

Ok, all cases is not necessary, but good judgement needs to be applied.
I've tried to look at a few inlines today, e.g. signbit in GCC is as good
as glibc builtin, which means __builtin_signbit should be used,
but already on IA-32 __builtin_signbitl is worse.
Although GCC 3.5 has really many math builtins, most of them do nothing
and thus are usually worse than what GLIBC provides (tried e.g. exp, tan).

	Jakub