[Buildroot] [PATCH] toolchain-wrapper: do not use deprecated -mfused-madd
Arnout Vandecappelle
arnout at mind.be
Fri Aug 11 21:00:13 UTC 2017
On 11-08-17 19:32, Waldemar Brodkorb wrote:
> Hi,
> Thomas Petazzoni wrote,
>
>> Hello,
>>
>> On Fri, 11 Aug 2017 07:28:48 +0200, Waldemar Brodkorb wrote:
>>> GCC deprecated -mfused-madd, -ffp-contract=off should
>>> be used for Xburst workaround.
>>> uClibc compilations will fail, because a gcc warning
>>> is emitted while checking for TLS support in the compiler.
>>
>> In which gcc version was -ffp-contract=off added ? Can we use that
>> unconditionally, or is it only available in recent gcc versions ?
>
> It was added in commit b9be572eda05cd23bbabd6409387d2c7ac782715.
>
> Not sure how to find when it was added in a release.
$ git describe --contains b9be572eda05cd23bbabd6409387d2c7ac782715
gcc-4_6_0-release~2941
So we should use something like:
ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_4_6),y)
TOOLCHAIN_WRAPPER_ARGS += -DBR_FP_CONTRACT_OFF
else
TOOLCHAIN_WRAPPER_ARGS += -DBR_NO_FUSED_MADD
endif
But actually, I'd much prefer this stuff to just be coded in
TOOLCHAIN_WRAPPER_OPTS. But that's a much bigger patch (series) so not for master.
Regards,
Arnout
> 4.6.4 seems to have it:
> https://gcc.gnu.org/onlinedocs/gcc-4.6.4/gcc/Optimize-Options.html#index-ffp_002dcontract-691
>
> I don't find it in earlier release docs.
>
> best regards
> Waldemar
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot
>
--
Arnout Vandecappelle arnout at mind be
Senior Embedded Software Architect +32-16-286500
Essensium/Mind http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint: 7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF
More information about the buildroot
mailing list