Implement the pack_clamp_s8 HLSL Function

[farzonl]

• Implement pack_clamp_s8 clang builtin,
• Link pack_clamp_s8 clang builtin with hlsl_intrinsics.h
• Add sema checks for pack_clamp_s8 to CheckHLSLBuiltinFunctionCall in SemaChecking.cpp
• Add codegen for pack_clamp_s8 to EmitHLSLBuiltinExpr in CGBuiltin.cpp
• Add codegen tests to clang/test/CodeGenHLSL/builtins/pack_clamp_s8.hlsl
• Add sema tests to clang/test/SemaHLSL/BuiltIns/pack_clamp_s8-errors.hlsl
• Create the int_dx_pack_clamp_s8 intrinsic in IntrinsicsDirectX.td
• Create the DXILOpMapping of int_dx_pack_clamp_s8 to 220 in DXIL.td
• Create the pack_clamp_s8.ll and pack_clamp_s8_errors.ll tests in llvm/test/CodeGen/DirectX/
• Create the int_spv_pack_clamp_s8 intrinsic in IntrinsicsSPIRV.td
• In SPIRVInstructionSelector.cpp create the pack_clamp_s8 lowering and map it to int_spv_pack_clamp_s8 in SPIRVInstructionSelector::selectIntrinsic.
• Create SPIR-V backend test case in llvm/test/CodeGen/SPIRV/hlsl-intrinsics/pack_clamp_s8.ll

DirectX

DXIL Opcode	DXIL OpName	Shader Model	Shader Stages
220	Pack4x8	6.6	()

SPIR-V

SClamp:

Description:

SClamp

Result is min(max(x, minVal), maxVal), where x, minVal and
maxVal are interpreted as signed integers. Result is undefined if
minVal > maxVal.

Result Type and the type of the operands must both be integer scalar
or integer vector types. Result Type and operand types must have the
same number of components with the same component width. Results are
computed per component.

Number	Operand 1	Operand 2	Operand 3	Operand 4
45	<id> x	<id> minVal	<id> maxVal

Test Case(s)

Example 1

//dxc pack_clamp_s8_test.hlsl -T lib_6_8 -enable-16bit-types -O0

export int8_t4_packed fn(int4 p1) {
    return pack_clamp_s8(p1);
}

HLSL:

Syntax

p32i8 pack_clamp_s8(sint16or32_only<4> v);

Type Description

Name	Template Type	Component Type	Size
ret	scalar	int8_t4_packed	1
v	vector	int or int16_t	4

Minimum Shader Model

This function is supported in the following shader models.

Shader Model	Supported
Shader Model 6.6 and higher shader models	yes

Shader Stages

See also

• Intrinsic Functions (DirectX HLSL)
• See Pack Intrinsics