[Bug ipa/97456] [10/11 Regression] An incorrect optimization causes a function to always return the same value when using -flto

[marxin at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97456

--- Comment #3 from Martin Liška <marxin at gcc dot gnu.org> ---
A bit reduced test-case:

$ #include <complex>

auto wrong(float &pos) -> int {
  auto a = std::complex(pos, pos);
  auto b = std::complex(0.0f, 0.0f);

  b = b + a;

  if (b == 0.0f)
    return 1;

  printf("%f\n", b.imag());
  return 0;
}

float val2 = 1.710780f;
float val3;

int main(int argc, char **argv) {
  auto val = argc == 1 ? val2 : val3;

  printf("val is %f\n", val);

  return (wrong(val), wrong(val));
}

It's not easy to bisect as it depends on definitions in complex.h.