Implement the WorldRayDirection HLSL Function

[farzonl]

• Implement WorldRayDirection clang builtin,
• Link WorldRayDirection clang builtin with hlsl_intrinsics.h
• Add sema checks for WorldRayDirection to CheckHLSLBuiltinFunctionCall in SemaChecking.cpp
• Add codegen for WorldRayDirection to EmitHLSLBuiltinExpr in CGBuiltin.cpp
• Add codegen tests to clang/test/CodeGenHLSL/builtins/WorldRayDirection.hlsl
• Add sema tests to clang/test/SemaHLSL/BuiltIns/WorldRayDirection-errors.hlsl
• Create the int_dx_WorldRayDirection intrinsic in IntrinsicsDirectX.td
• Create the DXILOpMapping of int_dx_WorldRayDirection to 148 in DXIL.td
• Create the WorldRayDirection.ll and WorldRayDirection_errors.ll tests in llvm/test/CodeGen/DirectX/
• Create the int_spv_WorldRayDirection intrinsic in IntrinsicsSPIRV.td
• In SPIRVInstructionSelector.cpp create the WorldRayDirection lowering and map it to int_spv_WorldRayDirection in SPIRVInstructionSelector::selectIntrinsic.
• Create SPIR-V backend test case in llvm/test/CodeGen/SPIRV/hlsl-intrinsics/WorldRayDirection.ll

DirectX

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

SPIR-V

WorldRayDirectionKHR

Short Description

WorldRayDirectionKHR - Ray direction in world space

Description

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

Valid Usage

• 
  
  VUID-WorldRayDirectionKHR-WorldRayDirectionKHR-04428
  The WorldRayDirectionKHR decoration must be used only within
  the IntersectionKHR , AnyHitKHR , ClosestHitKHR , or
  MissKHR Execution Model

• 
  
  VUID-WorldRayDirectionKHR-WorldRayDirectionKHR-04429
  The variable decorated with WorldRayDirectionKHR must be
  declared using the Input Storage Class

• 
  
  VUID-WorldRayDirectionKHR-WorldRayDirectionKHR-04430
  The variable decorated with WorldRayDirectionKHR must be
  declared as a three-component vector of 32-bit floating-point values

Test Case(s)

Example 1

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

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

SPIRV Example(s):

Example 2

//dxc WorldRayDirection_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 = WorldRayDirection();
}

HLSL:

The world-space direction for the current ray.

Syntax

float3 WorldRayDirection();

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