https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67600
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Known to work| |4.9.3 Keywords| |wrong-code Last reconfirmed| |2015-09-16 Component|libstdc++ |ipa CC| |hubicka at gcc dot gnu.org Ever confirmed|0 |1 Summary|[5/6] Segfault when |[5/6 Regression] Segfault |assigning only one char to |when assigning only one |ostreambuf_iterator<char> |char to |compiled with -O2 or -O3 |ostreambuf_iterator<char> | |compiled with -O2 or -O3 Target Milestone|--- |5.3 Known to fail| |5.2.0 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed. <bb 2>: std::basic_ostringstream<char>::basic_ostringstream (&ostr, 16); _52 = MEM[(char_type * *)&ostr + 48B]; returns NULL. Dump of assembler code for function main(): 0x0000000000400ad0 <+0>: push %rbx 0x0000000000400ad1 <+1>: mov $0x10,%esi 0x0000000000400ad6 <+6>: sub $0x180,%rsp 0x0000000000400add <+13>: lea 0x20(%rsp),%rdi 0x0000000000400ae2 <+18>: callq 0x400ab0 <_ZNSt19basic_ostringstreamIcSt11char_traitsIcESaIcEEC1ESt13_Ios_Openmode@plt> 0x0000000000400ae7 <+23>: mov 0x50(%rsp),%rax 0x0000000000400aec <+28>: lea 0x28(%rsp),%rsi 0x0000000000400af1 <+33>: lea 0x10(%rsp),%rdi => 0x0000000000400af6 <+38>: movb $0x58,(%rax) looks like a devirt issue again, -fno-devirtualize fixes it and -fdump-tree-all without it ICEs: > /space/rguenther/install/gcc-5.2/bin/g++ t.c -O2 -g -fdump-tree-all t.c: In function 'int main()': t.c:4:5: internal compiler error: Segmentation fault int main() ^ 0xacaeff crash_signal /space/rguenther/src/svn/gcc-5-branch/gcc/toplev.c:383 0x7cce20 symtab_node::name() const /space/rguenther/src/svn/gcc-5-branch/gcc/symtab.c:479 0xbe1083 eliminate_dom_walker::before_dom_children(basic_block_def*) /space/rguenther/src/svn/gcc-5-branch/gcc/tree-ssa-pre.c:4405 0xfaf581 dom_walker::walk(basic_block_def*) /space/rguenther/src/svn/gcc-5-branch/gcc/domwalk.c:188 0xbdf58b eliminate /space/rguenther/src/svn/gcc-5-branch/gcc/tree-ssa-pre.c:4540 0xbdf8a5 execute /space/rguenther/src/svn/gcc-5-branch/gcc/tree-ssa-pre.c:4978 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report.