[DirectX][DXIL] Align TableGen DXIL Op type spec with that of LLVM Intrinsic

[bharadwajy]

Problem Description

Consider an HLSL intrinsic with void return type, such as void barrier(mask). Its TableGen specification would be

  def int_dx_barrier  : Intrinsic<[], [llvm_i32_ty], [IntrNoDuplicate, IntrWillReturn]>;

The specification of DXIL Op that maps to it would be

  def Barrier : DXILOpMapping<80, barrier, int_dx_barrier,
                          "Inserts a memory barrier in the shader",
                          [llvm_void_ty, llvm_i32_ty]>;

There should be no need to specify overriding types for the DXIL Op Barrier, as its types are the same as those of the LLVM Intrinsic it maps to. Such a need arises because the current implementation in DXIL.td represents return types and parameter types as a single combined list with an assumption that return type at index 0 of the list.

Solution

The specification of return and parameter types needs to be separated as is done in LLVM Intrinsic specification. As a result, the type specification will be uniform across LLVM Intrinsic and DXIL Op. Consequently, DXIL Op type specification can inherit types from LLVM Intrinsic and can be specified more succinctly.

Changes to DXILEmitter to handle the separate specification of return and parameter types also need to be made.

[bharadwajy]

Taking a different design direction - see PR #87803. Closing.