<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/99118>99118</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
Implement the `fmod` 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 `fmod` clang builtin,
- [ ] Link `fmod` clang builtin with `hlsl_intrinsics.h`
- [ ] Add sema checks for `fmod` to `CheckHLSLBuiltinFunctionCall` in `SemaChecking.cpp`
- [ ] Add codegen for `fmod` to `EmitHLSLBuiltinExpr` in `CGBuiltin.cpp`
- [ ] Add codegen tests to `clang/test/CodeGenHLSL/builtins/fmod.hlsl`
- [ ] Add sema tests to `clang/test/SemaHLSL/BuiltIns/fmod-errors.hlsl`
- [ ] Create the `int_dx_fmod` intrinsic in `IntrinsicsDirectX.td`
- [ ] Create the `DXILOpMapping` of `int_dx_fmod` to `6` in `DXIL.td`
- [ ] Create the `fmod.ll` and `fmod_errors.ll` tests in `llvm/test/CodeGen/DirectX/`
- [ ] Create the `int_spv_fmod` intrinsic in `IntrinsicsSPIRV.td`
- [ ] In SPIRVInstructionSelector.cpp create the `fmod` lowering and map it to `int_spv_fmod` in `SPIRVInstructionSelector::selectIntrinsic`.
- [ ] Create SPIR-V backend test case in `llvm/test/CodeGen/SPIRV/hlsl-intrinsics/fmod.ll`
## DirectX
| DXIL Opcode | DXIL OpName | Shader Model | Shader Stages |
| ----------- | ----------- | ------------ | ------------- |
| 6 | FAbs | 6.0 | () |
## SPIR-V
# [OpFRem](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpFRem):
## Description:
The floating-point [*remainder*](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Remainder) whose sign matches the sign
of *Operand 1*.
*Result Type* must be a scalar or vector of [*floating-point
type*](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Floating).
The types of *Operand 1* and *Operand 2* both must be the same as
*Result Type*.
Results are computed per component. The resulting value is undefined if
*Operand 2* is 0. Otherwise, the result is the [*remainder*](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Remainder)
*r* of *Operand 1* divided by *Operand 2* where if *r* ≠ 0, the sign of
*r* is the same as the sign of *Operand 1*.
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<thead>
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<th>Word Count</th>
<th>Opcode</th>
<th>Results</th>
<th>Operands</th>
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<td class="tableblock halign-left valign-top"><p>5</p></td>
<td class="tableblock halign-left valign-top"><p>140</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>Operand 1</em></p></td>
<td
class="tableblock halign-left valign-top"><p><em><id></em><br />
<em>Operand 2</em></p></td>
</tr>
</tbody>
</table>
## Test Case(s)
### Example 1
```hlsl
//dxc fmod_test.hlsl -T lib_6_8 -enable-16bit-types -O0
export float4 fn(float4 p1, float4 p2) {
return fmod(p1, p2);
}
```
## HLSL:
Returns the floating-point remainder of x/y.
| *ret* fmod(*x*, *y*) |
|----------------------|
## Parameters
| Item | Description |
|--------------------------------------------------------|------------------------------------------------|
| <span id="x"></span><span id="X"></span>*x*<br/> | \[in\] The floating-point dividend.<br/> |
| <span id="y"></span><span id="Y"></span>*y*<br/> | \[in\] The floating-point divisor.<br/> |
## Return Value
The floating-point remainder of the *x* parameter divided by the *y* parameter.
## Remarks
The floating-point remainder is calculated such that x = i \* y + f, where i is an integer, f has the same sign as x, and the absolute value of f is less than the absolute value of y.
## 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 |
| *y* | same as input *x* | [**float**](/windows/desktop/WinProg/windows-data-types) | same dimension(s) as input *x* |
| *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 2 (DirectX HLSL)](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-sm2.md) and higher shader models | yes |
| [Shader Model 1 (DirectX HLSL)](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-sm1.md) | vs\_1\_1 |
## Requirements
| Requirement | Value |
|-------------------|--------------------------------------------------------------------------------------------|
| Header<br/> | <dl> <dt>Corecrt\_math.h</dt> </dl> |
## 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>
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