From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21107 invoked by alias); 3 May 2006 23:25:11 -0000 Received: (qmail 20977 invoked by uid 48); 3 May 2006 23:25:04 -0000 Date: Wed, 03 May 2006 23:25:00 -0000 Subject: [Bug c++/27412] New: Incorrect result with sse intrinsic while extracting int X-Bugzilla-Reason: CC Message-ID: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "gcc at povworld dot org" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2006-05/txt/msg00315.txt.bz2 List-Id: Following code sets a 4 32-bit int sse vector to 1 for all elements and extracts one int out of the vector. g++ returns an incorrect result when compiling with -O2 or -O3 but not with -O1 or -O0 // ----------------------- #include #include int main() { __m128i ix = _mm_set1_epi32(1); int res = ((int*)&ix)[1]; printf("results: %i\n", res); } // ----------------------- compiled with: $ g++-4.1.0 -O2 -msse2 expected result: 1 actual result: -1209151480 similar misbehavior by gcc-3.4.5 acutal result: 134513897 $ g++-4.1.0 -v Using built-in specs. Target: i686-pc-linux-gnu Configured with: /var/tmp/portage/gcc-4.1.0/work/gcc-4.1.0/configure --prefix=/usr --bindir=/usr/i686-pc-linux-gnu/gcc-bin/4.1.0 --includedir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.0/include --datadir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0 --mandir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0/man --infodir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0/info --with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.0/include/g++-v4 --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --disable-altivec --enable-nls --without-included-gettext --with-system-zlib --disable-checking --disable-werror --disable-libunwind-exceptions --disable-multilib --disable-libmudflap --disable-libssp --enable-java-awt=gtk --enable-languages=c,c++,java,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu Thread model: posix gcc version 4.1.0 (Gentoo 4.1.0) -- Summary: Incorrect result with sse intrinsic while extracting int Product: gcc Version: 4.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: gcc at povworld dot org GCC host triplet: i686 linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27412