pack-optimized issue with domain shader

Hi,

I am having an issue with a domain shader which reorganizes input/output signature in an unexpected way when pack-optimized compiler flag is used. This in turn gives the following error in dx12 debug layer:

D3D12 ERROR: ID3D12Device::CreateGraphicsPipelineState: Domain Shader - Pixel Shader linkage error: Signatures between stages are incompatible. Semantic 'CLIP' of the input stage has a hardware register component mask that is not a subset of the output of the previous stage. [ STATE_CREATION ERROR #662: CREATEGRAPHICSPIPELINESTATE_SHADER_LINKAGE_REGISTERMASK]

The signature passed through from VS-HS-DS-PS stages is this (it's in a shared header, so it should be the same in all stages):

struct PixelInput
{
	float4 pos : SV_POSITION;
	float  clip : SV_ClipDistance0;
	float4 pre : PREVIOUSPOSITION;
	float3 nor : NORMAL;
};

In the disassembly I can see this when using pack-optimized for domain shader:

; Output signature:
;
; Name                 Index   Mask Register SysValue  Format   Used
; -------------------- ----- ------ -------- -------- ------- ------
; PREVIOUSPOSITION         0   xyzw        0     NONE   float   xyzw
; SV_Position              0   xyzw        1      POS   float   xyzw
; SV_ClipDistance          0      w        2  CLIPDST   float      w
; NORMAL                   0   xyz         2     NONE   float   xyz

And when NOT using pack-optimized:

; Output signature:
;
; Name                 Index   Mask Register SysValue  Format   Used
; -------------------- ----- ------ -------- -------- ------- ------
; SV_Position              0   xyzw        0      POS   float   xyzw
; SV_ClipDistance          0   x           1  CLIPDST   float   x
; PREVIOUSPOSITION         0   xyzw        2     NONE   float   xyzw
; NORMAL                   0   xyz         3     NONE   float   xyz

And the pixel shader input signature when using pack-optimized:

; Input signature:
;
; Name                 Index   Mask Register SysValue  Format   Used
; -------------------- ----- ------ -------- -------- ------- ------
; SV_Position              0   xyzw        0      POS   float   xy
; SV_ClipDistance          0   x           1  CLIPDST   float
; PREVIOUSPOSITION         0   xyzw        2     NONE   float   xy w

The pack-optimized version of domain output and pixel input doesn't match as you see, which is a problem.
I am attaching the dissassemblies and command line args.
disasm.zip

Best regards,
Janos

Start by reproducing the domain-shader compilation with the attached command-line arguments and disassemblies, comparing output and pixel-input signatures with and without pack-optimized. Trace the signature-packing path responsible for the register assignment; done means the domain output and pixel input signatures link successfully under DirectX 12.