add a note about how we should implement this FIXME from the legalizer:

    // FIXME: revisit this when we have some kind of mechanism by which targets
    // can decided legality of vector constants, of which there may be very
    // many.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25733 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed