https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86590
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2018-07-20 Ever confirmed|0 |1 --- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> --- So we could try to somehow pattern-match this "is-this-string-compile-time-constant" test or add a __builtin_cstring_constant_p () ... after all we end up evaluating this to false in the end, using __builtin_strlen but then passing it the constant and folding it anyway. <bb 3> [local count: 10037315480]: # __s_63 = PHI <"Hello world"(2), __s_66(5)> _64 = *__s_63; _65 = __builtin_constant_p (_64); if (_65 == 0) goto <bb 6>; [5.50%] else goto <bb 4>; [94.50%] <bb 4> [local count: 9485263123]: if (_64 == 0) goto <bb 6>; [5.50%] else goto <bb 5>; [94.50%] <bb 5> [local count: 8963573645]: __s_66 = __s_63 + 1; goto <bb 3>; [100.00%] <bb 6> [local count: 1073741826]: # _67 = PHI <_65(3), _65(4)> if (_67 != 0) goto <bb 7>; [50.00%] else goto <bb 9>; [50.00%] <bb 7> [local count: 4880644630]: # __i_68 = PHI <0(6), __i_71(8)> _69 = "Hello world" + __i_68; _70 = *_69; if (_70 != 0) goto <bb 8>; [89.00%] else goto <bb 10>; [11.00%] <bb 8> [local count: 4343773717]: __i_71 = __i_68 + 1; goto <bb 7>; [100.00%] <bb 9> [local count: 536870913]: _72 = 11; <bb 10> [local count: 1073741817]: # _73 = PHI <__i_68(7), _72(9)> so we have if (complicated way to tell the string is constant) { yay, compute it inline with a loop! } else lenght = 11; stupid. Very stupid.