http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50682
--- Comment #4 from Zdenek Sojka <zsojka at seznam dot cz> 2011-11-27 13:13:45 UTC --- Created attachment 25919 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25919 another testcase This testcase doesn't need any -fno-* flags. It might be the same problem (the backtrace is the same). $ gcc -O2 -fnon-call-exceptions -mfma4 testcase.C ==18808== Invalid read of size 4 ==18808== at 0xB961F3: main_block_label(tree_node*) (tree-cfg.c:1092) ==18808== by 0xB9A56B: cleanup_dead_labels() (tree-cfg.c:1121) ==18808== by 0xBEAB9C: execute_cleanup_cfg_post_optimizing() (tree-optimize.c:162) ==18808== by 0xA89CF4: execute_one_pass(opt_pass*) (passes.c:2074) ==18808== by 0xA8A094: execute_pass_list(opt_pass*) (passes.c:2129) ==18808== by 0xBEB5BD: tree_rest_of_compilation(tree_node*) (tree-optimize.c:420) ==18808== by 0x83F949: cgraph_expand_function(cgraph_node*) (cgraphunit.c:1819) ==18808== by 0x8416EB: cgraph_optimize() (cgraphunit.c:1886) ==18808== by 0x841E59: cgraph_finalize_compilation_unit() (cgraphunit.c:1327) ==18808== by 0x6632EA: cp_write_global_declarations() (decl2.c:4050) ==18808== by 0xB7EE43: toplev_main(int, char**) (toplev.c:581) ==18808== by 0x674ED2C: (below main) (in /lib64/libc-2.12.2.so) ==18808== Address 0x50 is not stack'd, malloc'd or (recently) free'd ==18808== testcase.C: In function 'void test01()': testcase.C:21:1: internal compiler error: Segmentation fault Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. However, when the code is modified a little (ternary operator is replaced by if/else), the crash is different: $ gcc -O2 -fnon-call-exceptions -mfma4 testcase.C testcase.C: In function 'void test01()': testcase.C:21:1: error: BB 2 can not throw but has an EH edge testcase.C:21:1: internal compiler error: verify_flow_info failed Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions.