[PATCH v6 0/2] MR179: vkd3d-shader/hlsl: Add support for ddx(), ddy() intrinsics.

[Ethan Lee (＠flibitijibibo)]

SPIR-V already handled DSX/DSY, so only D3DBC/TPF needed new case blocks.

You'll notice that there's no test for this one - in addition to being a pretty straightforward translation for all possible formats, this feature uses the render target width/height and I wasn't sure if there was a good way to ensure that the test would always make sense.

Instead, I did the test manually, and it's what you'd expect (EDIT: Previously the test used a uniform which always optimized to 0, new test uses VPOS instead):

HLSL:
```
float4 main(float4 pos : sv_position) : sv_target
{
    float4 x = ddx(pos.x);
    float4 y = ddy(pos.y);
    return x + y;
}
```

D3DBC:
```
ps_3_0
dcl_position0 vPos
mov r0.xyzw, vPos.xyzw
mov r1.x, r0.x
dsx r1.x, r1.x
mov r0.x, r0.yxxx
dsy r0.x, r0.x
mov r1.xyzw, r1.x
mov r0.xyzw, r0.x
add r0.xyzw, r1.xyzw, r0.xyzw
mov oC0.xyzw, r0.xyzw
```

DXBC-TPF:
```
ps_4_0
dcl_input_ps_siv linear v0.xyzw, position
dcl_output o0.xyzw
dcl_temps 2
mov r0.xyzw, v0.xyzw
mov r1.x, r0.x
dsx r1.x, r1.x
mov r0.x, r0.yxxx
dsy r0.x, r0.x
mov r1.xyzw, r1.x
mov r0.xyzw, r0.x
add r0.xyzw, r1.xyzw, r0.xyzw
mov o0.xyzw, r0.xyzw
ret
```

Fixes https://bugs.winehq.org/show_bug.cgi?id=54827

--
  v6: tests: Add tests for ddx(), ddy() intrinsics.

https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/179