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From: "edwintorok at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/35643] New: gcc-4.2 -O1 -fstrict-aliasing misoptimization Date: Wed, 19 Mar 2008 18:51:00 -0000 [thread overview] Message-ID: <bug-35643-15165@http.gcc.gnu.org/bugzilla/> (raw) When I compile the testcase with -O2, or with '-O1 -fstrict-aliasing' incorrect code is generated. The testcase calls abort() in this case. This is a regression in gcc-4.2 only: gcc-4.1 and gcc-4.3 do not show the bug. $ gcc-4.2 -O1 test.i -o ok && ./ok $ gcc-4.2 -O2 test.i -o fails && ./fails Aborted $ gcc-4.2 -O1 -fstrict-aliasing test.i -o fails2 && ./fails2 Aborted $ gcc-4.2 -O3 test.i -o fails3 && ./fails3 Aborted The testcase gives no warnings: $ gcc-4.2 -Wall -W -O2 -Wstrict-aliasing test.i The original code that is miscompiled is ClamAV, but only if -O3 is used. I created an initial reduced testcase using delta. Manually inlining some functions show this bug even at -O2 on the reduced testcase. I reproduced this on 2 different systems: edwin@lightspeed2:~$ uname -a Linux lightspeed2 2.6.25-rc4-00134-g84c6f60 #4 Sun Mar 9 19:40:34 EET 2008 x86_64 GNU/Linux edwin@lightspeed2:~$ gcc-4.2 -v Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --disable-libmudflap --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.2.3 (Debian 4.2.3-2) I also reproduced the bug with gcc 4.2.3 built with --enable-checking=yes: edwin@lightspeed2:~$ gcc-4.2.3/inst/bin/gcc -O1 -fstrict-aliasing test.i -o fails && ./fails Aborted edwin@lightspeed2:~$ gcc-4.2.3/inst/bin/gcc -v Using built-in specs. Target: x86_64-linux-gnu Configured with: ../configure --enable-languages=c --prefix=/home/edwin/gcc-4.2.3/obj/../inst --enable-checking=yes --disable-multilib --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap Thread model: posix gcc version 4.2.3 The second system: edwin@thunder:~$ uname -a Linux thunder 2.6.25-rc5-00323-g9a9e0d6 #22 SMP PREEMPT Sun Mar 16 10:23:46 EET 2008 i686 GNU/Linux edwin@thunder:~$ gcc-4.2 -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --disable-libmudflap --enable-targets=all --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.2.3 (Debian 4.2.3-2) -- Summary: gcc-4.2 -O1 -fstrict-aliasing misoptimization Product: gcc Version: 4.2.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: edwintorok at gmail dot com GCC build triplet: x86_64-linux-gnu GCC host triplet: x86_64-linux-gnu GCC target triplet: x86_64-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35643
next reply other threads:[~2008-03-19 18:51 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2008-03-19 18:51 edwintorok at gmail dot com [this message] 2008-03-19 18:55 ` [Bug rtl-optimization/35643] " edwintorok at gmail dot com 2008-03-19 19:36 ` edwintorok at gmail dot com 2008-03-19 19:57 ` [Bug rtl-optimization/35643] [4.2 Regression] " rguenth at gcc dot gnu dot org 2008-05-19 20:35 ` jsm28 at gcc dot gnu dot org 2009-03-31 15:35 ` jsm28 at gcc dot gnu dot org
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