Re: Bug#754054: perl: FTBFS on mips: Bad mojo! at make_patchnum.pl line 111.

On Tue, Jul 08, 2014 at 10:54:36PM +0300, Niko Tyni wrote:
> On Mon, Jul 07, 2014 at 08:00:37AM +0300, Niko Tyni wrote:
> > Package: perl
> > Version: 5.18.2-5
> > Severity: serious
> > X-Debbugs-Cc: [email protected]
> > 
> > The perl package failed to build on mips:
> >  LD_LIBRARY_PATH=/build/perl\-sdOt09/perl\-5.18.2${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH  ./miniperl -Ilib make_patchnum.pl
> >  Bad mojo! at make_patchnum.pl line 111.
> 
> > This is reproducible on gabrielli.
> 
> A test case would be
> 
>   gabrielli% cat ~/t.pl
>   print ( (q{foo'} =~ /[^']+'/) ?  "ok\n" : "not ok\n" );
>   gabrielli% perl ~/t.pl
>   ok
>   gabrielli% ./miniperl ~/t.pl
>   not ok
> 
> This is a shared build; the static build doesn't exhibit the bug and
> passes the full test suite. The bug only shows up with -fPIC.
> 
> An educated guess narrowed it down to regcomp.c. The above test fails
> when regcomp.c is built with gcc-4.9 at -O2 but works with gcc-4.9 at
> -O0 and gcc-4.8 at -O2.
> 
> I'll patch the package to lower the optimization level of regcomp.c
> for now.  Assuming a test build succeeds on gabrielli, I hope to upload
> tomorrow.
> 
> Distilling a proper gcc bug report about this seems rather arduous, and
> I don't really expect to get around to it. Help from the MIPS porters
> on that would be appreciated.

The problem is due to the -ftree-vrp optimization, enabled at -O2. I
will continue investigating, but in the meantime using -fno-tree-vrp
should also workaround the problem without lowering too much the
optimization level.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
[email protected]                 http://www.aurel32.net