<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/99157>99157</a>
        </td>
    </tr>

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

    <tr>
      <th>Labels</th>
      <td>
            metabug,
            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 `step` clang builtin,
- [ ] Link `step` clang builtin with `hlsl_intrinsics.h`
- [ ] Add sema checks for `step` to `CheckHLSLBuiltinFunctionCall` in `SemaChecking.cpp`
- [ ] Add codegen for `step` to `EmitHLSLBuiltinExpr` in `CGBuiltin.cpp`
- [ ] Add codegen tests to `clang/test/CodeGenHLSL/builtins/step.hlsl`
- [ ] Add sema tests to `clang/test/SemaHLSL/BuiltIns/step-errors.hlsl`
- [ ] Create the `int_spv_step` intrinsic in `IntrinsicsSPIRV.td`
- [ ] In SPIRVInstructionSelector.cpp create the `step` lowering and map  it to `int_spv_step` in `SPIRVInstructionSelector::selectIntrinsic`.
- [ ] Create SPIR-V backend test case in `llvm/test/CodeGen/SPIRV/hlsl-intrinsics/step.ll`

## DirectX

There were no DXIL opcodes found for `step`.

## SPIR-V

# Step:

## Description:
**Step**  
  
Result is 0.0 if *x* \< *edge*; otherwise result is 1.0.  
  
The operands must all be a scalar or vector whose component type is
floating-point.  
  
*Result Type* and the type of all operands must be the same type.
Results are computed per component.

<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>Number</th>
<th>Operand 1</th>
<th>Operand 2</th>
<th>Operand 3</th>
<th>Operand 4</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p>48</p></td>
<td
class="tableblock halign-left valign-top"><p><em>&lt;id&gt;</em><br />
<em>edge</em></p></td>
<td
class="tableblock halign-left valign-top"><p><em>&lt;id&gt;</em><br />
<em>x</em></p></td>
<td></td>
<td></td>
</tr>
</tbody>
</table>



## Test Case(s)

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

export float4 fn(float4 p1, float4 p2) {
 return step(p1, p2);
}
```
## HLSL:

Compares two values, returning 0 or 1 based on which value is greater.



| *ret* step(*y*, *x*) |
|----------------------|



 

## Parameters



| Item | Description |
|--------------------------------------------------------|---------------------------------------------------------------|
| <span id="y"></span><span id="Y"></span>*y*<br/> | \[in\] The first floating-point value to compare.<br/>  |
| <span id="x"></span><span id="X"></span>*x*<br/> | \[in\] The second floating-point value to compare.<br/> |



 

## Return Value

1 if the *x* parameter is greater than or equal to the *y* parameter; otherwise, 0.

## Remarks

This function uses the following formula: (*x* >= *y*) ? 1 : 0. The function returns either 0 or 1 depending on whether the *x* parameter is greater than the *y* parameter. To compute a smooth interpolation between 0 and 1, use the [**smoothstep**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/dx-graphics-hlsl-smoothstep.md) HLSL intrinsic function.

## 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 |
|-------|----------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------|--------------------------------|
| *y*   | [**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                            |
| *x*   | same as input *y* | [**float**](/windows/desktop/WinProg/windows-data-types) | same dimension(s) as input *y* |
| *ret* | same as input *y* | [**float**](/windows/desktop/WinProg/windows-data-types) | same dimension(s) as input *y* |



 

## 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) | yes (vs\_1\_1 and ps\_1\_4) |



 

## 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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