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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 9 Nov 2015 15:31:22 +0000
Message-ID: <CAFEAcA-dkuA2k0Pw8MLRc8u13urPuAbQCpF90xMZOY38EPkkFQ@mail.gmail.com>
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Subject: Re: [Qemu-devel] [PATCH for-2.5] configure: Don't disable
 optimization for non-fortify builds
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: John Snow <jsnow@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, Patch Tracking <patches@linaro.org>

On 9 November 2015 at 15:28, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
>
> On 09/11/2015 16:14, Peter Maydell wrote:
>> Commit b553a0428014636bc inadvertently disabled optimization
>> for all non-fortify builds. Fix this bug so we only do an
>> unoptimized build if we want debug.
>>
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>>  configure | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/configure b/configure
>> index b687764..46fd8bd 100755
>> --- a/configure
>> +++ b/configure
>> @@ -4451,6 +4451,8 @@ if test "$gcov" = "yes" ; then
>>    LDFLAGS="-fprofile-arcs -ftest-coverage $LDFLAGS"
>>  elif test "$fortify_source" = "yes" ; then
>>    CFLAGS="-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
>> +elif test "$debug" = "no"; then
>> +  CFLAGS="-O2 $CFLAGS"
>>  fi
>
> I think what was intended is:
>
> if test "$gcov" = "yes" ; then
>   CFLAGS="-fprofile-arcs -ftest-coverage -g $CFLAGS"
>   LDFLAGS="-fprofile-arcs -ftest-coverage $LDFLAGS"
> elif test "$debug" = "no" ; then
>   if test "$fortify_source" = "yes"; then
>     CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
>   fi
>   CFLAGS="-O2 $CFLAGS"
> fi
>
> ... so that --enable-debug does not disable _FORTIFY_SOURCE.

Commit b553a04280146 specifically sets fortify_source=no
in the handling of the --enable-debug option, so John
obviously intended that it should disable _FORTIFY_SOURCE.
The feature_test_macros(7) manpage says _FORTIFY_SOURCE
only kicks in at -O1 and above anyway, so that makes sense.

thanks
-- PMM