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Date: Wed, 14 Dec 2016 22:11:49 -0600
From: "A. Wilcox" <AWilcox@...cox-Tech.com>
To: musl@...ts.openwall.com
Subject: Re: musl + PowerPC + GCC 5

On 14/12/16 04:53, Szabolcs Nagy wrote:
> * A. Wilcox <awilfox@...lielinux.org> [2016-12-14 04:02:39 -0600]:
> i think the simplest fix is to config with --disable-decimal-float

/usr/src/sys-devel/gcc-5.4.0-r2/work/gcc-5.4.0/configure
--host=powerpc-foxkit-linux-musl --target=powerpc-foxkit-linux-musl
--prefix=/usr --bindir=/usr/powerpc-foxkit-linux-musl/gcc-bin/5.4.0
--includedir=/usr/lib/gcc/powerpc-foxkit-linux-musl/5.4.0/include
--datadir=/usr/share/gcc-data/powerpc-foxkit-linux-musl/5.4.0
--mandir=/usr/share/gcc-data/powerpc-foxkit-linux-musl/5.4.0/man
--infodir=/usr/share/gcc-data/powerpc-foxkit-linux-musl/5.4.0/info
--with-gxx-include-dir=/usr/lib/gcc/powerpc-foxkit-linux-musl/5.4.0/include/g++-v5
--enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --enable-nls
--without-included-gettext --enable-checking=release
--enable-libstdcxx-time --enable-shared --enable-threads=posix
--disable-multilib --disable-altivec --disable-fixed-point
--disable-decimal-float --disable-libgcj --enable-libgomp
--disable-libmudflap --enable-libssp --disable-libcilkrts
--disable-libmpx --disable-vtable-verify --disable-libvtv --enable-lto
--without-isl --disable-libsanitizer

Note "--disable-decimal-float".  I receive the same error.

> the second simplest fix is to patch the ifdef logic (e.g. define
> BFP_FMT "%Le") but then the conversion code would be broken at
> runtime: the code is compiled with -mlong-double-128 and musl
> expects 64 bit long double. (most likely the bootstrap process
> does not depend on this to work so this is a workaround hack
> that only breaks 128bit float to decimal conversion.)

That sounds unacceptable for production code.  I do not understand the
inner workings of floating point though.

> the correct way on musl is to build libgcc without -mlong-double-128
> and without all the 128bit (TF mode) float stuff, but this may need
> some configure and build system changes as i don't immediately see
> an option to turn tf mode things off.

I cannot seem to disable -mlong-double-128 no matter what I patch. :(

Regards,
--arw


-- 
A. Wilcox (awilfox)
Open-source programmer (C, C++, Python)
https://code.foxkit.us/u/awilfox/


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