http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55614
Bug #: 55614 Summary: vector extensions cause movdqa to be generated for memcpy on unaligned buffer Classification: Unclassified Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: soren.sandm...@gmail.com Created attachment 28891 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28891 Program in which memcpy() is miscompiled When the attached program is compiled with 4.7.2 with -O2, the memcpy() is expanded to a movdqa instruction, but the buffer passed is unaligned, so we get a crash. localhost:~% gcc -v Using built-in specs. COLLECT_GCC=/usr/bin/gcc COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.7.2/lto-wrapper Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --disable-build-with-cxx --disable-build-poststage1-with-cxx --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto --enable-plugin --enable-initfini-array --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix gcc version 4.7.2 20120921 (Red Hat 4.7.2-2) (GCC)