Implement the `dst` HLSL Function

[farzonl]

• implement dst algorithm in the hlsl_intrinsics.h
• Add HLSL codegen tests to clang/test/CodeGenHLSL/builtins/dst.hlsl
• Add sema tests to clang/test/SemaHLSL/BuiltIns/dst-errors.hlsl

DirectX

There were no DXIL opcodes found for dst.

SPIR-V

There were no SPIRV GL ext opcodes found for dst.

OpFMul:

Description:

Floating-point multiplication of Operand 1 and Operand 2.

Result Type must be a scalar or vector of floating-point
type.

The types of Operand 1 and Operand 2 both must be the same as
Result Type.

Results are computed per component.

Word Count	Opcode	Results	Operands
5	133	<id> Result Type	Result <id>	<id> Operand 1	<id> Operand 2

Test Case(s)

Example 1

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

export float4 fn(float4 p1, float4 p2) {
    return dst(p1, p2);
}

HLSL:

Calculates a distance vector.

Syntax

fVector dst(
  in fVector src0,
  in fVector src1
);

Parameters

src0 [in]

Type: fVector

The first vector.

src1 [in]

Type: fVector

The second vector.

Return value

Type: fVector

The computed distance vector.

Remarks

This intrinsic function provides the same functionality as the Vertex Shader instruction dst.

See also

Intrinsic Functions

[davidcook-msft]

@farzonl to outline the header implementation.

[farzonl]

@davidcook-msft this ready for planning.