[Bug rtl-optimization/62041] vector fneg codegen uses a subtract instead of an xor (x86-64)

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62041

--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> ---
(The gimple version works with -ffast-math at least)

In fold-const.c, fold_real_zero_addition_p has:

  /* In a vector or complex, we would need to check the sign of all zeros.  */
  if (TREE_CODE (addend) != REAL_CST)
    return false;

We should probably check the sign of all zeros indeed.