https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88971
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> This is because it still needs to generate the std::string objects at the
> caller
> site (outside of the if (print)). This involves quite some code to get
> rid of, and even at -O3 we do not inline basic_string::basic_string it seems
> (ISTR that is out-of-line in the library):
>
> __asm__ __volatile__("mfence" : : : "memory");
> _6 = MEM[(const int *)&data + 4B];
> if (_6 > 0)
> goto <bb 3>; [41.48%]
> else
> goto <bb 11>; [58.52%]
>
> <bb 3> [local count: 445388109]:
> std::basic_string<char>::basic_string (&D.39204, "<", &D.39205);
> _7 = MEM[(char * *)&D.39204];
> _8 = _7 + 18446744073709551592;
> if (_8 != &_S_empty_rep_storage)
> goto <bb 5>; [10.00%]
> else
> goto <bb 4>; [90.00%]
Looks like you're using -D_GLIBCXX_USE_CXX11_ABI=0 but the OP is not.
