http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58653
Bug ID: 58653 Summary: wrong code (segfaults) at -O3 on x86_64-linux-gnu in 64-bit mode (affecting gcc 4.6 to trunk) Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu The current gcc trunk (as well as 4.6, 4.7, and 4.8) mis-compiles the following code on x86_64-linux at -O3 in 64-bit mode, resulting in a segfault. $ gcc-trunk -v Using built-in specs. COLLECT_GCC=gcc-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../gcc-trunk/configure --enable-languages=c,c++,objc,obj-c++,fortran,lto --disable-werror --enable-checking=release --with-gmp=/usr/local/gcc-trunk --with-mpfr=/usr/local/gcc-trunk --with-mpc=/usr/local/gcc-trunk --with-cloog=/usr/local/gcc-trunk --prefix=/usr/local/gcc-trunk Thread model: posix gcc version 4.9.0 20131006 (experimental) [trunk revision 203227] (GCC) $ $ gcc-trunk -m64 -O2 small.c; a.out $ gcc-trunk -m32 -O3 small.c; a.out $ $ gcc-trunk -m64 -O3 small.c; a.out Segmentation fault (core dumped) $ gcc-4.8 -m64 -O3 small.c; a.out Segmentation fault (core dumped) $ gcc-4.7 -m64 -O3 small.c; a.out Segmentation fault (core dumped) $ gcc-4.6 -m64 -O3 small.c; a.out Segmentation fault (core dumped) $ --------------------------------- int a, c, e[5][2]; unsigned int d; int main () { for (d = 0; d < 2; d++) if (a ? 0 : e[c + 3][d] & e[c + 4][d]) break; return 0; }