https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71009
--- Comment #3 from Eric Gallager <egall at gwmail dot gwu.edu> --- Still happens with: $ /usr/local/bin/g++ -v Using built-in specs. COLLECT_GCC=/usr/local/bin/g++ COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/i386-apple-darwin9.8.0/7.0.0/lto-wrapper Target: i386-apple-darwin9.8.0 Configured with: ../configure --disable-werror --enable-languages=c,c++,lto,objc,obj-c++ --enable-stage1-checking=release -C --with-system-libunwind --enable-secureplt --enable-frame-pointer --enable-debug --without-isl --enable-objc-gc --enable-host-shared CC=/usr/local/bin/gcc CXX=/usr/local/bin/g++ Thread model: posix gcc version 7.0.0 20160526 (experimental) (GCC) This time I attached gdb and got a backtrace: (gdb) bt #0 0x00ed6004 in internal_error () #1 0x00ed5040 in fancy_abort () #2 0x00719077 in gen_reg_rtx () #3 0x0048fc28 in gen_split_343 () #4 0x00569b62 in split_8 () #5 0x00720956 in try_split () #6 0x00a6a7be in split_insn () #7 0x00a6ec9a in split_all_insns () #8 0x00a6ecfb in (anonymous namespace)::pass_split_after_reload::execute () #9 0x00a3c567 in execute_one_pass () #10 0x00a3cb59 in execute_pass_list_1 () #11 0x00a3cb6c in execute_pass_list_1 () #12 0x00a3cb6c in execute_pass_list_1 () #13 0x00a3cbba in execute_pass_list () #14 0x0063b7d9 in cgraph_node::expand () #15 0x0063d244 in symbol_table::compile () #16 0x0063f74d in symbol_table::finalize_compilation_unit () #17 0x00b19b51 in compile_file () #18 0x0177f168 in toplev::main () #19 0x01780a24 in main () I'll have to rebuild gcc for debugging to get further info.