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Re: [PATCH] Enable non-complex math builtins from C99 for Bionic
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Bernhard Reutner-Fischer <rep dot dot dot nop at gmail dot com>
- Cc: Kirill Yukhin <kirill dot yukhin at gmail dot com>, Maxim Kuvyrkov <maxim at kugelworks dot com>, Alexander Ivchenko <aivchenk at gmail dot com>, Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 5 Sep 2013 19:46:37 +0000
- Subject: Re: [PATCH] Enable non-complex math builtins from C99 for Bionic
- Authentication-results: sourceware.org; auth=none
- References: <CACysShhz+0gyscs-fkN7evVq1bGCMmgj09n6YQFAriKKn2C+HA at mail dot gmail dot com> <Pine dot LNX dot 4 dot 64 dot 1307082206160 dot 7307 at digraph dot polyomino dot org dot uk> <CACysShhZkdphnWqy8qaCKotQEp7sYizsGi8ZJ0hg3wBTx7Xenw at mail dot gmail dot com> <yddbo4rw21v dot fsf at lokon dot CeBiTec dot Uni-Bielefeld dot DE> <CACysShhKGY1UCUthvTmDSeVS7D4QV=BpAD2VbzmPv7wLYYFqhA at mail dot gmail dot com> <20130822082500 dot GA19152 at bart> <CACysShgCzaTtSDapaw-+vkpUtqBtfRpKVWzd=NUOtrGP1AMPtg at mail dot gmail dot com> <81715983-8771-40A3-862F-FAAB584ABEF1 at kugelworks dot com> <CACysShjrmxK_4hkyDKEEzy=1+d=G2XzMP0VL40x_7gim-z7Ozg at mail dot gmail dot com> <1C61DE2C-4F72-4B00-A7A6-08AC2D671F79 at kugelworks dot com> <20130905110229 dot GA53348 at msticlxl57 dot ims dot intel dot com> <140ef809b68 dot 2760 dot 0f39ed3bcad52ef2c88c90062b7714dc at gmail dot com>
On Thu, 5 Sep 2013, Bernhard Reutner-Fischer wrote:
> uClibc has C99 math support optionally as well as other optional, nonstandard
> feature sets. Your patch does not seem to check (in a cross-compilable
> fashion, of course) if C99 math is supported in libc or not, thus regressing
> on uClibc with C99_MATH enabled.
It is a basic principle that it should be possible to bootstrap cross
tools by building the compiler, once, then using it to build runtime
libraries. We haven't got there yet, but configure-time tests for library
features that affect how the compiler behaves are best avoided so as to
support such bootstraps - and if present, it's best for there to be a
corresponding configure option to override them, and a command-line option
to control things on a per-multilib basis. To the extent that we do have
configure support for checking library headers if those are available when
the compiler is configured, it only supports checking the default multilib
and not headers for other multilibs.
--
Joseph S. Myers
joseph@codesourcery.com