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Re: Old compiler optimizations in installed headers
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Paul Eggert <eggert at cs dot ucla dot edu>
- Cc: <libc-alpha at sourceware dot org>
- Date: Fri, 22 May 2015 18:08:44 +0000
- Subject: Re: Old compiler optimizations in installed headers
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 10 dot 1505221433160 dot 16611 at digraph dot polyomino dot org dot uk> <555F6F3D dot 4030506 at cs dot ucla dot edu>
On Fri, 22 May 2015, Paul Eggert wrote:
> On 05/22/2015 08:03 AM, Joseph Myers wrote:
> > (b) where such optimizations are present in glibc headers and only
> > relevant for GCC versions before some baseline (maybe 4.1 or 4.3), we
> > should be willing to remove them to simplify the code
>
> This all sounds reasonable. How much of a maintenance difference would it be
> to select 4.1 vs 4.3 for the baseline? If that's significant, the last GCC
> 4.3.x release was in 2009 which is quite a while ago if we're talking about
> development environments, so I suggest going with 4.3.
There are some 4.3 conditionals in byteswap.h headers. Other than that it
doesn't look like there would be much advantage in 4.3 over 4.0 (3.4 would
be sufficient for bits/string2.h, 4.0 for bits/mathinline.h on various
architectures).
--
Joseph S. Myers
joseph@codesourcery.com