https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121334
--- Comment #1 from Robin Dapp <rdapp at gcc dot gnu.org> ---
We actually don't consider the constant legitimate via
riscv_legitimate_constant_p but expr.cc says
if (!targetm.legitimate_constant_p (mode, y))
{
y = force_const_mem (mode, y);
/* If the target's cannot_force_const_mem prevented the spill,
assume that the target's move expanders will also take care
of the non-legitimate constant. */
if (!y)
y = y_cst;
our cannot_force_const_mem prohibits spilling to memory because we can't handle
VLA vectors:
/* There's no way to calculate VL-based values using relocations. */
subrtx_iterator::array_type array;
FOR_EACH_SUBRTX (iter, array, x, ALL)
if (GET_CODE (*iter) == CONST_POLY_INT)
return true;
That leaves us with a non-spillable const_vector that we have no expander for.
So from my current understanding of it there is no way around writing one.
