https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67816
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> --- Reduction result looks the same. Maybe critical is that the compiler is built with release checking (though that would be pretty serious - code gen depending on CHECKING) > /gcc/spec/sb-czerny-head-64/x86_64/install-201510042000/bin/gcc -O3 iterate.i > -v -S Using built-in specs. COLLECT_GCC=/gcc/spec/sb-czerny-head-64/x86_64/install-201510042000/bin/gcc Target: x86_64-pc-linux-gnu Configured with: /gcc/spec/sb-czerny-head-64/gcc/configure --disable-bootstrap --prefix=/gcc/spec/sb-czerny-head-64/x86_64/install-201510042000 --enable-languages=c,c++,fortran --enable-threads=posix --disable-nls --enable-__cxa_atexit --enable-clocale=gnu --enable-checking=release --disable-libstdcxx-pch --disable-libsanitizer --disable-libcilkrts Thread model: posix gcc version 6.0.0 20151004 (experimental) [trunk revision 228461] (GCC) COLLECT_GCC_OPTIONS='-O3' '-v' '-S' '-mtune=generic' '-march=x86-64' /home/gcc/spec/sb-czerny-head-64/x86_64/install-201510042000/bin/../libexec/gcc/x86_64-pc-linux-gnu/6.0.0/cc1 -fpreprocessed iterate.i -quiet -dumpbase iterate.i -mtune=generic -march=x86-64 -auxbase iterate -O3 -version -o iterate.s GNU C11 (GCC) version 6.0.0 20151004 (experimental) [trunk revision 228461] (x86_64-pc-linux-gnu) compiled by GNU C version 4.8.3 20141208 [gcc-4_8-branch revision 218481], GMP version 5.1.2, MPFR version 3.1.2, MPC version 1.0 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C11 (GCC) version 6.0.0 20151004 (experimental) [trunk revision 228461] (x86_64-pc-linux-gnu) compiled by GNU C version 4.8.3 20141208 [gcc-4_8-branch revision 218481], GMP version 5.1.2, MPFR version 3.1.2, MPC version 1.0 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: f102ae58a97e9c99e076c734516f015f iterate.c: In function 'Iterate': iterate.c:17:5: internal compiler error: in duplicate_thread_path, at tree-ssa-threadupdate.c:2446 0xade9af duplicate_thread_path /gcc/spec/sb-czerny-head-64/gcc/gcc/tree-ssa-threadupdate.c:2445 0xade9af thread_through_all_blocks(bool) /gcc/spec/sb-czerny-head-64/gcc/gcc/tree-ssa-threadupdate.c:2632 0xa3c628 execute /gcc/spec/sb-czerny-head-64/gcc/gcc/tree-ssa-dom.c:622 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <http://gcc.gnu.org/bugs.html> for instructions.