[arch-general] [arch-dev-public] [signoff] gcc-4.5 toolchain rebuild

Emmanuel Benisty benisty.e at gmail.com
Fri Apr 16 21:48:41 EDT 2010


Thanks for your reply Allan.

On Sat, Apr 17, 2010 at 5:30 AM, Allan McRae <allan at archlinux.org> wrote:
> On 17/04/10 00:03, Emmanuel Benisty wrote:
>>
>> Just out of curiosity, what is the plan regarding this issue (quoted
>> from the gcc changelog):
>>
>> On x86 targets, code containing floating-point calculations may run
>> significantly slower when compiled with GCC 4.5 in strict C99
>> conformance mode than they did with earlier GCC versions. This is due
>> to stricter standard conformance of the compiler and can be avoided by
>> using the option -fexcess-precision=fast;
>>
>
> From what I understand, this requires passing -std=c99 (or equivalent) to
> the compiler for it to use strict C99 mode.  So most software will not be
> affected.  Of course, the maintainer of any software the does set C99 mode
> should consider this.

If it does affect only that type of code and if you recommend the
maintainers to use this option in those cases then wouldn't it simpler
to add it to /etc/makepkg.conf by default and thus make it a
no-brainer for maintainers?


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