[Bug middle-end/122323] [14/15/16 Regression] Failed to optimize copysign

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122323

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
y.cc should be

#include <cstdlib>

float t(float x)
{
  return -std::abs (x);
}