<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/99099>99099</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
Implement the `ddy` 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` clang builtin,
- [ ] Link `ddy` clang builtin with `hlsl_intrinsics.h`
- [ ] Add sema checks for `ddy` to `CheckHLSLBuiltinFunctionCall` in `SemaChecking.cpp`
- [ ] Add codegen for `ddy` to `EmitHLSLBuiltinExpr` in `CGBuiltin.cpp`
- [ ] Add codegen tests to `clang/test/CodeGenHLSL/builtins/ddy.hlsl`
- [ ] Add sema tests to `clang/test/SemaHLSL/BuiltIns/ddy-errors.hlsl`
- [ ] Create the `int_dx_ddy` intrinsic in `IntrinsicsDirectX.td`
- [ ] Create the `DXILOpMapping` of `int_dx_ddy` to `84` in `DXIL.td`
- [ ] Create the `ddy.ll` and `ddy_errors.ll` tests in `llvm/test/CodeGen/DirectX/`
- [ ] Create the `int_spv_ddy` intrinsic in `IntrinsicsSPIRV.td`
- [ ] In SPIRVInstructionSelector.cpp create the `ddy` lowering and map it to `int_spv_ddy` in `SPIRVInstructionSelector::selectIntrinsic`.
- [ ] Create SPIR-V backend test case in `llvm/test/CodeGen/SPIRV/hlsl-intrinsics/ddy.ll`
## DirectX
| DXIL Opcode | DXIL OpName | Shader Model | Shader Stages |
| ----------- | ----------- | ------------ | ------------- |
| 84 | DerivCoarseY | 6.0 | ('library', 'pixel', 'compute', 'amplification', 'mesh', 'node') |
## SPIR-V
# [OpDPdy](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpDPdy):
## Description:
Same result as either [**OpDPdyFine**](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpDPdyFine) or
[**OpDPdyCoarse**](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpDPdyCoarse) on *P*. Selection of which one is
based on external factors.
*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):
**Shader**
<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>208</p></td>
<td
class="tableblock halign-left valign-top"><p><em><id></em><br />
<em>Result Type</em></p></td>
<td class="tableblock halign-left valign-top"><p><a
href="#ResultId"><em>Result <id></em></a></p></td>
<td
class="tableblock halign-left valign-top"><p><em><id></em><br />
<em>P</em></p></td>
</tr>
</tbody>
</table>
## Test Case(s)
### Example 1
```hlsl
//dxc ddy_test.hlsl -T lib_6_8 -enable-16bit-types -O0
export float4 fn(float4 p1) {
return ddy(p1);
}
```
## HLSL:
Returns the partial derivative of the specified value with respect to the screen-space y-coordinate.
| *ret* ddy(*x*) |
|----------------|
This function computes the partial derivative with respect to the screen-space y-coordinate. To compute the partial derivative with respect to the screen-space x-coordinate, use the [**ddx**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-ddx.md) function.
This function is only supported in pixel shaders.
## Parameters
| Item | Description |
|--------------------------------------------------------|----------------------------------------|
| <span id="x"></span><span id="X"></span>*x*<br/> | \[in\] The specified value.<br/> |
## Return Value
The partial derivative of the *x* parameter.
## Type Description
| Name | [**Template Type**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-intrinsic-functions.md) | [**Component Type**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-intrinsic-functions.md) | Size |
|-------|----------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------|--------------------------------|
| *x* | [**scalar**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-intrinsic-functions.md), **vector**, or **matrix** | [**float**](/windows/desktop/WinProg/windows-data-types) | any |
| *ret* | same as input *x* | [**float**](/windows/desktop/WinProg/windows-data-types) | same dimension(s) as input *x* |
## 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 |
| [Shader Model 4](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-sm4.md) | yes |
| [Shader Model 3 (DirectX HLSL)](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-sm3.md) | yes |
| [Shader Model 2 (DirectX HLSL)](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-sm2.md) | yes in ps\_2\_x; unsupported in ps\_2\_0. |
| [Shader Model 1 (DirectX HLSL)](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-sm1.md) | no |
This function is supported in the following types of shaders:
| Vertex | Hull | Domain | Geometry | Pixel | Compute |
|--------|------|--------|----------|-------|---------|
| | | | | x | |
## See also
<dl> <dt>
[**Intrinsic Functions (DirectX HLSL)**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-intrinsic-functions.md)
</dt> </dl>
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzUGl1P47j215gXK1Xq0EIfeCiF7iLN3EHLaHbvE3Lj08YXx45sB9r99VfHTtKEFpiP5c7cCEF8bJ9vnw8H7pzcaIALMrkkk6sTXvvC2Is1t38brU5WRuwuEkoml5RMruhNWSkoQXtKpqkQOzJNaa643tBVLZWXmrAFSef7DR-kfnhpLX2SvsDJQjl1L7W3UjuZu1FBpukAy1wI6qDkNC8gf3B0bWwPqTc4WODU7x_uPlxG7Mta514aveBK4SqpcdUdlDyslHozyqvqGKXcCNiAPkrlupS-R-R6W9k98sVvDfgtzB6cdw3GoBLClggjbLkwAn4DjTQIWzaacoQthdiNUFEv6uYVpCh1gzFweNNiTMBaY91RxAsL3AP1BSBGqf292N43yuiM1Uh-0xnvSlrI_V8jL17Hd_XXzYdP1UdeVVJvEKVZH5LxhiLw_HSvY9z3OvLGZqNodq5FA7hvZI3wqK2IU6nH8sAChC0bWQhbvq0bVz2-rZy725s_vhzh_kbTMHWjnbd1cNs7UJB7Y9GVaD4g15BR5gms1JsgYskrSqVvzH_AUHD9FyiQbE6yuQujjlUyTUfHJEYkyRe64vkDaBG0SHPu4A1NBtqELdHPkv1Jb9xaNb6HPywjLKOt5iPsbEHR7PRThQeI9sb_4mUc3xVcgKUfjQDVB9x5vgGHkAZRsn_oG-NDQNJDdH4aGQErHxeGWwf_DoDpKA1_CTsn7EzJleV2R9gZYQg7q-QW1H6Ym7KqPewBvKyUXMuco4n24BJcsR9pI-KWWctQp7looA6E9vtUXd2KHZlcEXZeeF85tDhbEra0sJHO293oobBGGzcydtNYK0FzuQqCkWot1xLEuLXkqPClIixrMLMZYhzYD1xuZRVkCFOUknR-h9ay4GrlKXcUpC_AIoeEzQmbR2xLqSGO34_jSGNGjUWWh_SjLd-bg5bKjBpNCZvfEjYf0XgkpdEYDZ8KmRfUaKDSkXS-4g4EroatB6u5omuOx9eNgm7DL8Lmf0T1ft5VKAMta-fpCiinLueKW2osfQzHPgTcIPpaGe6l3iSVkdqTdO7j5veQftnQQslrh9ELg9rN9fU1PZucUtC5EZia6ecCKB4Oo7HaeJLCF0EY1ATQjNGV9H3RcT3yHcSK-uyERxIOfY87eqCiUbdcurDykasaqDeoCP4Qdws85dzLR8Q_oCoxiXQxFXEYrXaIRAoMiiFmB2daWr7B0imOUPfXW8jrcEbSeYhc76Hxjsh9JMFmo-aoTi4XvOIrqaR_l-jQwx4iROOhhM1jcG7OWGQmW3i-UkCy6zjKjdpYU1d9AHV-h0uuCGPBIxApSwmbEMYoMv3_vJiw5YHQvgAu9iPbmyDZ9Z_GCrowtfZxewD25mO-PD4XD4F7aSNYrsULswdQHNnBaMg2NhFHhRDYEDgXtRPsv1Imf6AFV3KjEwVrH07SRifeVISxSB31cxopVXt-xD-Cl6Xnr2Im6fy7cZNsASX-ZVPlSXYpBWHTDb5FQnEyW6zswDECuB-0BovfQwkkW3CSzgsL67idsCwycCO6hX223pKIsCV_i92fpdnbr9PnoZMP3BoBvQCWDuuhz1gnLzhm_HOH0TBMhjQSV-Ci6y0Wf0DHODtN40_ozNImIottTrGTwfo69Gw0-UyVXN1P789pAhoZSMbTlfQJ5kJHk09NXQ3bylhPQ6o_pWtN2HnzXo1jGXkZchqlFnxtNZIh7DxMohax5r3q87WXLTSWbf33R9gdE2nFrZdcDZNnTMYV5CFnNMk2XARYQHBoYcKa3ALoxFU8B7pLcmOskJp7GA30GyrtuQVMqw3ThM23IbfM9uV68uzZl82dJdp0vm4uDmhTm78ozLdxTT-bFuN3I9z2EGIrULumKWxLWCG2L1euG-mLejXKDbZoH2VujTNrf2VCEn-SOmOELVfKrNDTIlSAe_CmSpzNGw8MjVkmgluiQyYby6tC5i4JvZ0Q21EpUPWtGkfHVNuWSa6u0C8hlEqhNaIu1AZuNDg_t9zyEjxY99z4Nx5K-u1PbN26JuVlR_na5xu27ntIki1cxTWVIga9bRfUQnnFdRwM1vx1bE3j8RjgYnyLLehkQSaXUoe_V6GkfnbyRs-2HDkTjQXiwaZfcFdr0deOeMMSroiWGxoU89igS3xm1tDYN0I0vv0ZykpxD23h_hO9vLvBSFqPdo3XDzhedP3Lr87ynfwbDs7AD5yG733-AZJfgaJ3ABsvfeZqsVf-RQ0W74CQtdjIN2yyBfb2cVByb-W2bTT7koWk3xcsMizMU49JwpZ_Sn1rzWY_mwjueawqWqfhevdGiD1I0DhqO3Gpq9p3Fng3LgM5IUvQLtyohfrrKP2Xg99HqWVZl4NbxhfS2iCjYSBcG6XMk9SbJrPREne7gypmcIP5g0_A1zHyw7nte8_Z8SM3uRyIOvlfHbBMjMf7M2ZhDRZ0DokrJ00k5FrQQm4KsENbBX3uwH299l-Q9fRnBRNXnvai_W5wI_6cyYwSdt5cwMfins1-Ht_ZM75_1ATsl5KOPZMOq2BHJot7hr-2JLuktR4WyfvpdPSKnONfSs5xT05tviGMvdmkvR5yYxds1m1Xsf9O0cXdL2A9bANnv9cqfjy6MiWXoSmgv4EpwdtdGNyGDgXfFk0ndxBbu9djsOGgD94bshfCu5cePAK2wzUv6qr9KARAuXKmu2sVKhT82UL4_YVFm327j4C0_YbujjnTL1odtbcxQTLavKO4J-IiE7Nsxk_gYnzGxuPJ7Gw8Piku0vMcVoxNJnx9tk6nZ6vx7AzG49VkLPgpwPREXrCUnaZn4-l4NpmMx6N8PU1PV-fjbHrGZ-N0Rk5TKLlUI6Uey5GxmxPpXA0Xs1k6m50ovgLlwj9YMFaC56t6E-7UFoSx5ksqyebd1-ZmJur5YFl7_d5OGE-yebt2cnViL5CJZFVvHDlNlXTe7dny0iu42P8Xx_CLMmLpbH5SW3XximGbT72BWGXNfyD3hC2D3GjRKPrjBftvAAAA__8W9PzB">