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Re: [gcc-4.4.5] wrong code, segfault in libtommath-0.42.0 with "-O2 -fgraphite-identity"

From: Marcin Mirosław <marcin at mejor dot pl>
To: Ian Lance Taylor <iant at google dot com>
Cc: gcc-help at gcc dot gnu dot org
Date: Thu, 23 Jun 2011 21:21:19 +0200
Subject: Re: [gcc-4.4.5] wrong code, segfault in libtommath-0.42.0 with "-O2 -fgraphite-identity"
Openpgp: id=04423B81
References: <4DF88C65.4080502@mejor.pl> <mcr39j9vivw.fsf@coign.corp.google.com> <4DFA7524.8050404@mejor.pl> <mcrwrgksu04.fsf@coign.corp.google.com>

W dniu 2011-06-17 11:10, Ian Lance Taylor pisze:
> Many programs crash at -O2 but not at -O1.  That is because -O2
> implements more aggressive optimizations.  It does not mean that the
> compiler is wrong.
> 
> Often the program will work if you use -fno-strict-aliasing
> -fno-strict-overflow along with -O2.  If so, it still does not indicate
> a compiler bug; it indicates a program bug.

Thanks for explanation!
libtommath works with -fno-strict-aliasing -fno-strict-overflow , i
notified upstream (but i can't prepare test case ).
Regards,
Marcin.

References:
- [gcc-4.4.5] wrong code, segfault in libtommath-0.42.0 with "-O2 -fgraphite-identity"
  - From: Marcin MirosÅaw
- Re: [gcc-4.4.5] wrong code, segfault in libtommath-0.42.0 with "-O2 -fgraphite-identity"
  - From: Ian Lance Taylor
- Re: [gcc-4.4.5] wrong code, segfault in libtommath-0.42.0 with "-O2 -fgraphite-identity"
  - From: Marcin Mirosław
- Re: [gcc-4.4.5] wrong code, segfault in libtommath-0.42.0 with "-O2 -fgraphite-identity"
  - From: Ian Lance Taylor

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