[PATCH] D40591: [SelectionDAG][X86] Teach promotion legalization for fp_to_sint/fp_to_uint to insert an assertsext/assertzext based on the original type

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

Here's the comment from the existing code

  // Assert that the converted value fits in the original type.  If it doesn't
  // (eg: because the value being converted is too big), then the result of the
  // original operation was undefined anyway, so the assert is still correct.
  //
  // NOTE: fp-to-uint to fp-to-sint promotion guarantees zero extend. For example:
  //   before legalization: fp-to-uint16, 65534. -> 0xfffe
  //   after legalization: fp-to-sint32, 65534. -> 0x0000fffe
  return DAG.getNode(N->getOpcode() == ISD::FP_TO_UINT ?
                     ISD::AssertZext : ISD::AssertSext, dl, NVT, Res,
                     DAG.getValueType(N->getValueType(0).getScalarType()));


https://reviews.llvm.org/D40591