FORCE_FAIL
  if defined ensure fail to check for vacuous passing

IMPLEMENT_VOTE_INTRINSICS
  if defined use intrinsics
  else define as uninterpreted functions

IMPLEMENT_VECTOR
  if defined use builtin vector-scalar functions
  else work around

IMPLEMENT_SURFACE
  if defined use surfaces
  else ignore for now

KERNEL_BUG
  if defined then don't fix the bug
