Implement the `WorldRayOrigin` HLSL Function

[farzonl]

• Implement WorldRayOrigin clang builtin,
• Link WorldRayOrigin clang builtin with hlsl_intrinsics.h
• Add sema checks for WorldRayOrigin to CheckHLSLBuiltinFunctionCall in SemaChecking.cpp
• Add codegen for WorldRayOrigin to EmitHLSLBuiltinExpr in CGBuiltin.cpp
• Add codegen tests to clang/test/CodeGenHLSL/builtins/WorldRayOrigin.hlsl
• Add sema tests to clang/test/SemaHLSL/BuiltIns/WorldRayOrigin-errors.hlsl
• Create the int_dx_WorldRayOrigin intrinsic in IntrinsicsDirectX.td
• Create the DXILOpMapping of int_dx_WorldRayOrigin to 147 in DXIL.td
• Create the WorldRayOrigin.ll and WorldRayOrigin_errors.ll tests in llvm/test/CodeGen/DirectX/
• Create the int_spv_WorldRayOrigin intrinsic in IntrinsicsSPIRV.td
• In SPIRVInstructionSelector.cpp create the WorldRayOrigin lowering and map it to int_spv_WorldRayOrigin in SPIRVInstructionSelector::selectIntrinsic.
• Create SPIR-V backend test case in llvm/test/CodeGen/SPIRV/hlsl-intrinsics/WorldRayOrigin.ll

DirectX

DXIL Opcode	DXIL OpName	Shader Model	Shader Stages
147	WorldRayOrigin	6.3	('library', 'intersection', 'anyhit', 'closesthit', 'miss')

SPIR-V

WorldRayOriginKHR

Short Description

WorldRayOriginKHR - Ray origin in world space

Description

WorldRayOriginKHR
A variable decorated with the WorldRayOriginKHR decoration will
specify the origin of the ray being processed, in world space. The value
is the parameter passed into the pipeline trace ray instruction.

Valid Usage

• 
  VUID-WorldRayOriginKHR-WorldRayOriginKHR-04431
  
  The WorldRayOriginKHR decoration must be used only within the
  IntersectionKHR , AnyHitKHR , ClosestHitKHR , or
  MissKHR Execution Model

• 
  VUID-WorldRayOriginKHR-WorldRayOriginKHR-04432
  
  The variable decorated with WorldRayOriginKHR must be declared
  using the Input Storage Class

• 
  VUID-WorldRayOriginKHR-WorldRayOriginKHR-04433
  
  The variable decorated with WorldRayOriginKHR must be declared
  as a three-component vector of 32-bit floating-point values

Test Case(s)

Example 1

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

export float3 fn() {
    return WorldRayOrigin();
}

SPIRV Example(s):

Example 2

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

[shader("intersection")]
void fn() {
float3 	ret = WorldRayOrigin();
}

HLSL:

The world-space origin of the current ray.

Syntax

float3 WorldRayOrigin();

Remarks

This function can be called from the following raytracing shader types:

• Any Hit Shader
• Closest Hit Shader
• Intersection Shader
• Miss Shader

See also

Direct3D 12 Raytracing HLSL Reference