<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/99101>99101</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Implement the `ddy_fine` HLSL Function
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            metabug,
            backend:DirectX,
            HLSL,
            backend:SPIR-V,
            bot:HLSL
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          farzonl
      </td>
    </tr>
</table>

<pre>
    - [ ] Implement `ddy_fine` clang builtin,
- [ ] Link `ddy_fine` clang builtin with `hlsl_intrinsics.h`
- [ ] Add sema checks for `ddy_fine` to `CheckHLSLBuiltinFunctionCall` in `SemaChecking.cpp`
- [ ] Add codegen for `ddy_fine` to `EmitHLSLBuiltinExpr` in `CGBuiltin.cpp`
- [ ] Add codegen tests to `clang/test/CodeGenHLSL/builtins/ddy_fine.hlsl`
- [ ] Add sema tests to `clang/test/SemaHLSL/BuiltIns/ddy_fine-errors.hlsl`
- [ ] Create the `int_dx_ddy_fine` intrinsic in `IntrinsicsDirectX.td`
- [ ] Create the `DXILOpMapping` of `int_dx_ddy_fine` to  `86` in `DXIL.td`
- [ ] Create the  `ddy_fine.ll` and `ddy_fine_errors.ll` tests in `llvm/test/CodeGen/DirectX/`
- [ ] Create the `int_spv_ddy_fine` intrinsic in `IntrinsicsSPIRV.td`
- [ ] In SPIRVInstructionSelector.cpp create the `ddy_fine` lowering and map  it to `int_spv_ddy_fine` in `SPIRVInstructionSelector::selectIntrinsic`.
- [ ] Create SPIR-V backend test case in `llvm/test/CodeGen/SPIRV/hlsl-intrinsics/ddy_fine.ll`

## DirectX

| DXIL Opcode | DXIL OpName | Shader Model | Shader Stages |
| ----------- | ----------- | ------------ | ------------- |
| 86 | DerivFineY | 6.0 | ('library', 'pixel', 'compute', 'amplification', 'mesh', 'node') |

## SPIR-V

# [OpDPdyFine](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpDPdyFine):

## Description:
  
Result is the partial derivative of *P* with respect to the window *y*
coordinate.Uses local differencing based on the value of *P* for the
current fragment and its immediate neighbor(s).  
  
*Result Type* must be a scalar or vector of [*floating-point
type*](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Floating) using the IEEE 754 encoding. The component width must
be 32 bits.  
  
The type of *P* must be the same as *Result Type*. *P* is the value to
take the derivative of.  
  
This instruction is only valid in the **Fragment** [Execution
Model](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Execution_Model).

[Capability](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Capability):  
**DerivativeControl**

<table>
<colgroup>
<col style="width: 20%" />
<col style="width: 20%" />
<col style="width: 20%" />
<col style="width: 20%" />
<col style="width: 20%" />
</colgroup>
<thead>
<tr>
<th>Word Count</th>
<th>Opcode</th>
<th>Results</th>
<th>Operands</th>
<th></th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p>4</p></td>
<td class="tableblock halign-left valign-top"><p>211</p></td>
<td
class="tableblock halign-left valign-top"><p><em>&lt;id&gt;</em><br />
<em>Result Type</em></p></td>
<td class="tableblock halign-left valign-top"><p><a
href="#ResultId"><em>Result &lt;id&gt;</em></a></p></td>
<td
class="tableblock halign-left valign-top"><p><em>&lt;id&gt;</em><br />
<em>P</em></p></td>
</tr>
</tbody>
</table>



## Test Case(s)

 
 ### Example 1
```hlsl
//dxc ddy_fine_test.hlsl -T lib_6_8 -enable-16bit-types -O0

export float4 fn(float4 p1) {
    return ddy_fine(p1);
}
```
## HLSL:

Computes a high precision partial derivative with respect to the screen-space x-coordinate.

## Syntax

``` syntax
float ddy_fine(
  in float value
);
```

## Parameters

<dl> <dt>

*value* \[in\]
</dt> <dd>

Type: **float**

The input value.

</dd> </dl>

## Return value

Type: **float**

The high precision partial derivative of *value*.

## Remarks

The following overloaded versions are also available:

``` syntax
float2 ddy_fine(float2 value);
float3 ddy_fine(float3 value);
float4 ddy_fine(float4 value);  
```

### Minimum Shader Model

This function is supported in the following shader models.



| Shader Model                                                                | Supported |
|-----------------------------------------------------------------------------|-----------|
| [Shader Model 5](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/d3d11-graphics-reference-sm5.md) and higher shader models | yes       |



 

This function is supported in the following types of shaders:



| Vertex | Hull | Domain | Geometry | Pixel | Compute |
|--------|------|--------|----------|-------|---------|
|        |      |        |          | x     |         |



 

## See also

<dl> <dt>

[Intrinsic Functions](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-intrinsic-functions.md)
</dt> <dt>

[Shader Model 5](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/d3d11-graphics-reference-sm5.md)
</dt> </dl>
</pre>
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