glibc2.32 build error for powerpc64-unknown-linux-gnu

[Chris Packham]

On 3/09/20 10:53 pm, Adhemerval Zanella wrote:
>
> On 03/09/2020 06:09, Chris Packham wrote:
>> On 3/09/20 2:39 pm, Chris Packham wrote:
>>> On 3/09/20 9:14 am, Chris Packham wrote:
>>>> On 3/09/20 2:20 am, Adhemerval Zanella wrote:
>>>>> On 02/09/2020 05:05, Chris Packham wrote:
>>>>>> On 2/09/20 7:40 am, Adhemerval Zanella wrote:
>>>>>>> On 30/08/2020 07:40, Chris Packham via Libc-help wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> crosstool-ng was recently updated to add glibc-2.32. We're seeing
>>>>>>>> the
>>>>>>>> following error building for powerpc64
>>>>>>>>
>>>>>>>> [ALL  ]      In file included from
>>>>>>>> ../sysdeps/powerpc/powerpc32/power4/multiarch/wordcopy-ppc32.c:26,
>>>>>>>> [ALL  ]                       from
>>>>>>>> ../sysdeps/powerpc/powerpc64/multiarch/wordcopy-ppc64.c:18:
>>>>>>>> [ALL  ]      ../string/wordcopy.c: In function
>>>>>>>> '_wordcopy_fwd_aligned':
>>>>>>>> [ERROR]      ../string/wordcopy.c:98:26: error: 'a1' may be used
>>>>>>>> uninitialized in this function [-Werror=maybe-uninitialized]
>>>>>>>> [ALL  ]         98 |       ((op_t *) dstp)[0] = a1;
>>>>>>>> [ALL  ]            |       ~~~~~~~~~~~~~~~~~~~^~~~
>>>>>>>>
>>>>>>>> Looking at the code in question I think it's a spurious warning.
>>>>>>>> There
>>>>>>>> even appears to be an attempt to turn off the warning in
>>>>>>>> sysdeps/generic/Makefile but the file is #included for powerpc so
>>>>>>>> the
>>>>>>>> flags applied.
>>>>>>>>
>>>>>>>> Bug report with full logs
>>>>>>>> https://github.com/crosstool-ng/crosstool-ng/issues/1380
>>>>>>>>
>>>>>>> I haven't see it with gcc version 9.3.1, so it might be something
>>>>>>> related
>>>>>>> to gcc 10 or newer.  I will build a gcc 10 and check if I can
>>>>>>> reproduce it.
>>>>>> I just tried a crosstool-ng config selecting gcc 9.3.0 and I still see
>>>>>> the same error.
>>>>>>
>>>>> I just tried to reproduce it building powerpc64-linux-gnu,
>>>>> powerpc-linux-gnu
>>>>> and powerpc-linux-gnu-power4 (with --with-cpu-power4) with both gcc
>>>>> 9.3.1
>>>>> and 10, but without success. Are you using any special flags or
>>>>> patch for gcc?
>>>> There are a collection of patches
>>>> https://github.com/crosstool-ng/crosstool-ng/tree/master/packages/gcc/10.2.0
>>>> mostly just brought forward from older gcc versions. I'll try
>>>> disabling them.
>>> Even without any of the glibc or gcc patches and I still see the same
>>> error.
>> I think I might know why you can't see the error. crosstool-ng sets
>> -Werror when building glibc. So it's a warning that gets promoted to an
>> error by -Werror.
>>
>> I'll update crosstool-ng to stop doing that for powerpc64 + glibc-2.32.
> We add -Werror by default since 2.21 and have added --disable-werror to
> disable it.  I am trying to understand why you are seeing this error in
> your environment because this specific code has not been touched in a long
> time and constantly built *all* supported ABI some different gcc versions [1].
>
> And the last report for gcc 9 [1] and gcc 10 has not shown any issue, neither
> any testing I did with gcc 8, gcc9, or gcc10.  I will try to build some
> powerpc permutations with --with-cpu and/or --disable-multi-arch.
>
>
> [1] https://sourceware.org/pipermail/libc-testresults/2020q3/thread.html
> [2] https://sourceware.org/pipermail/libc-testresults/2020q3/006398.html
> [3] https://sourceware.org/pipermail/libc-testresults/2020q3/006397.html

Hmm the plot thickens.

If it helps this is the configure line crosstool-ng ends up using

BUILD_CC='x86_64-build_pc-linux-gnu-gcc' 
CC='powerpc64-unknown-linux-gnu-gcc -g -O2 -U_FORTIFY_SOURCE ' CFLAGS='' 
AR='powerpc64-unknown-linux-gnu-ar' 
RANLIB='powerpc64-unknown-linux-gnu-ranlib' '/bin/bash' 
'/home/runner/work/crosstool-ng/crosstool-ng/.build/powerpc64-unknown-linux-gnu/src/glibc/configure' 
'--prefix=/usr' '--build=x86_64-build_pc-linux-gnu' 
'--host=powerpc64-unknown-linux-gnu' 
'--cache-file=/home/runner/work/crosstool-ng/crosstool-ng/.build/powerpc64-unknown-linux-gnu/build/build-libc-final/multilib/config.cache' 
'--without-cvs' '--disable-profile' '--without-gd' 
'--with-headers=/home/runner/work/crosstool-ng/crosstool-ng/x-tools/powerpc64-unknown-linux-gnu/powerpc64-unknown-linux-gnu/sysroot/usr/include' 
'--disable-debug' '--disable-sanity-checks' '--enable-obsolete-rpc' 
'--enable-kernel=5.5.5' '--with-__thread' '--with-tls' '--enable-shared' 
'--enable-add-ons=no' '--with-pkgversion=crosstool-NG UNKNOWN'

It's the same between a glibc-2.31 build and a glibc-2.32 build.