[PATCH] [AArch64 NEON] Invalid constant is used in vselect condition.

[Andrea Di Biagio]

  Hi Kevin,

  your patch looks good to me.
  My original code worked under the wrong assumption that the vector element type and the type of each ConstantSDNode in the build_vector were the same.
  However, when promoting the integer operand of a legally typed build_vector, the operand type and the vector element type do not need to be the same (See method 'DAGTypeLegalizer::PromoteIntOp_BUILD_VECTOR' in LegalizeIntegerTypes.cpp).

  in AArch64 backend, the following dag sequence:

  C0: i1 = Constant<0>
  C1: i1 = Constant<-1>
  V: v8i1 = BUILD_VECTOR C1, C1, C0, C0, C0, C0, C0, C0

  is type-legalized into:

  NewC0: i32 = Constant<0>
  NewC1: i32 = Constant<1>
  V: v8i8 = BUILD_VECTOR NewC1, NewC1, NewC0, NewC0, NewC0, NewC0, NewC0, NewC0

  Forcing a getZeroExtend to VTBits to ensure that the new constant is correctly generated looks good to me!

  Thanks,
  Andrea Di Biagio

http://llvm-reviews.chandlerc.com/D2503