Implement the `sign` HLSL Function

[llvm-beanz]

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

DirectX

There were no DXIL opcodes found for sign.

SPIR-V

FSign:

Description:

FSign

Result is 1.0 if x > 0, 0.0 if x = 0, or -1.0 if x < 0.

The operand x must be a scalar or vector whose component type is
floating-point.

Result Type and the type of x must be the same type. Results are
computed per component.

Number	Operand 1	Operand 2	Operand 3	Operand 4
6	<id> x

Test Case(s)

Example 1

//dxc sign_test.hlsl -T lib_6_8  -enable-16bit-types -spirv -fspv-target-env=universal1.5 -fcgl -O0

export int4 fn(float4 p1) {
    return sign(p1);
}

Example 2

//dxc sign_1_test.hlsl -T lib_6_8 -enable-16bit-types -O0

export int4 fn(uint4 p1) {
    return sign(p1);
}

Example 3

//dxc sign_2_test.hlsl -T lib_6_8 -enable-16bit-types -O0

export int4 fn(int4 p1) {
    return sign(p1);
}

HLSL:

Returns the sign of x.

ret sign(x)

Parameters

Item	Description
x	[in] The input value.

Return Value

Returns -1 if x is less than zero; 0 if x equals zero; and 1 if x is greater than zero.

Type Description

Name	Template Type	Component Type	Size
x	scalar, vector, or matrix	float, int	any
ret	same as input x	int	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) and higher shader models	yes
Shader Model 1 (DirectX HLSL)	yes (vs_1_1 and ps_1_4)

See also

Intrinsic Functions (DirectX HLSL)