<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/99227>99227</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
Implement the `pack_s8` 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 `pack_s8` clang builtin,
- [ ] Link `pack_s8` clang builtin with `hlsl_intrinsics.h`
- [ ] Add sema checks for `pack_s8` to `CheckHLSLBuiltinFunctionCall` in `SemaChecking.cpp`
- [ ] Add codegen for `pack_s8` to `EmitHLSLBuiltinExpr` in `CGBuiltin.cpp`
- [ ] Add codegen tests to `clang/test/CodeGenHLSL/builtins/pack_s8.hlsl`
- [ ] Add sema tests to `clang/test/SemaHLSL/BuiltIns/pack_s8-errors.hlsl`
- [ ] Create the `int_dx_pack_s8` intrinsic in `IntrinsicsDirectX.td`
- [ ] Create the `DXILOpMapping` of `int_dx_pack_s8` to `220` in `DXIL.td`
- [ ] Create the `pack_s8.ll` and `pack_s8_errors.ll` tests in `llvm/test/CodeGen/DirectX/`
- [ ] Create the `int_spv_pack_s8` intrinsic in `IntrinsicsSPIRV.td`
- [ ] In SPIRVInstructionSelector.cpp create the `pack_s8` lowering and map it to `int_spv_pack_s8` in `SPIRVInstructionSelector::selectIntrinsic`.
- [ ] Create SPIR-V backend test case in `llvm/test/CodeGen/SPIRV/hlsl-intrinsics/pack_s8.ll`
## DirectX
| DXIL Opcode | DXIL OpName | Shader Model | Shader Stages |
| ----------- | ----------- | ------------ | ------------- |
| 220 | Pack4x8 | 6.6 | () |
## SPIR-V
# [OpBitcast](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpBitcast):
## Description:
Bit pattern-preserving type conversion.
*Result Type* must be an [**OpTypePointer**](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpTypePointer), or a
scalar or vector of [*numerical-type*](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Numerical).
*Operand* must have a type of [**OpTypePointer**](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpTypePointer), or a
scalar or vector of [*numerical-type*](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Numerical). It must be a
different type than *Result Type*.
Before **version 1.5**: If either *Result Type* or *Operand* is a
pointer, the other must be a pointer or an integer scalar.
Starting with **version 1.5**: If either *Result Type* or *Operand* is a
pointer, the other must be a pointer, an integer scalar, or an integer
vector.
If both *Result Type* and the type of *Operand* are pointers, they both
must point into same [storage class](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Storage_Class).
Behavior is undefined if the [storage class](https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#Storage_Class) of *Result
Type* does not match the one used by the operation that produced the
value of *Operand*.
If *Result Type* has the same number of components as *Operand*, they
must also have the same component width, and results are computed per
component.
If *Result Type* has a different number of components than *Operand*,
the total number of bits in *Result Type* must equal the total number of
bits in *Operand*. Let *L* be the type, either *Result Type* or
*Operand’s* type, that has the larger number of components. Let *S* be
the other type, with the smaller number of components. The number of
components in *L* must be an integer multiple of the number of
components in *S*. The first component (that is, the only or
lowest-numbered component) of *S* maps to the first components of *L*,
and so on, up to the last component of *S* mapping to the last
components of *L*. Within this mapping, any single component of *S*
(mapping to multiple components of *L*) maps its lower-ordered bits to
the lower-numbered components of *L*.
<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>124</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</em></p></td>
</tr>
</tbody>
</table>
## Test Case(s)
### Example 1
```hlsl
//dxc pack_s8_test.hlsl -T lib_6_8 -enable-16bit-types -O0
export int8_t4_packed fn(int4 p1) {
return pack_s8(p1);
}
```
## HLSL:
## Syntax
```syntax
p32i8 pack_s8(any_int16or32<4> v);
```
## Type Description
| Name | [**Template Type**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/../direct3dhlsl/dx-graphics-hlsl-data-types.md)| [**Component Type**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/../direct3dhlsl/dx-graphics-hlsl-data-types.md) | Size |
|-------|--------------------------------------------------------------------|----------------------------------------------------------------------|------|
| *ret* | [**scalar**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/../direct3dhlsl/dx-graphics-hlsl-scalar.md) | [**int8_t4_packed**](../WinProg/windows-data-types) | 1 |
| *v* | [**vector**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/../direct3dhlsl/dx-graphics-hlsl-vector.md) | [**int**](../WinProg/windows-data-types), [**int16_t**](https://github.com/microsoft/DirectXShaderCompiler/wiki/16-Bit-Scalar-Types), [**uint**](../WinProg/windows-data-types), or [**uint16_t**](https://github.com/microsoft/DirectXShaderCompiler/wiki/16-Bit-Scalar-Types) | 4 |
## Minimum Shader Model
This function is supported in the following shader models.
|Shader Model | Supported|
|-------------|----------|
|[Shader Model 6.6](https://microsoft.github.io/DirectX-Specs/d3d/HLSL_ShaderModel6_6) and higher shader models | yes |
## Shader Stages
## See also
- [**Intrinsic Functions (DirectX HLSL)**](https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src//direct3dhlsl/../direct3dhlsl/dx-graphics-hlsl-intrinsic-functions.md)
- **See [Pack Intrinsics](https://microsoft.github.io/DirectX-Specs/d3d/HLSL_SM_6_6_Pack_Unpack_Intrinsics#pack-intrinsics)**
</pre>
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