Implement the `InstanceID` HLSL Function

[farzonl]

• Implement InstanceID clang builtin,
• Link InstanceID clang builtin with hlsl_intrinsics.h
• Add sema checks for InstanceID to CheckHLSLBuiltinFunctionCall in SemaChecking.cpp
• Add codegen for InstanceID to EmitHLSLBuiltinExpr in CGBuiltin.cpp
• Add codegen tests to clang/test/CodeGenHLSL/builtins/InstanceID.hlsl
• Add sema tests to clang/test/SemaHLSL/BuiltIns/InstanceID-errors.hlsl
• Create the int_dx_InstanceID intrinsic in IntrinsicsDirectX.td
• Create the DXILOpMapping of int_dx_InstanceID to 141 in DXIL.td
• Create the InstanceID.ll and InstanceID_errors.ll tests in llvm/test/CodeGen/DirectX/
• Create the int_spv_InstanceID intrinsic in IntrinsicsSPIRV.td
• In SPIRVInstructionSelector.cpp create the InstanceID lowering and map it to int_spv_InstanceID in SPIRVInstructionSelector::selectIntrinsic.
• Create SPIR-V backend test case in llvm/test/CodeGen/SPIRV/hlsl-intrinsics/InstanceID.ll

DirectX

DXIL Opcode	DXIL OpName	Shader Model	Shader Stages
141	InstanceID	6.3	('library', 'intersection', 'anyhit', 'closesthit')

SPIR-V

InstanceCustomIndexKHR

Short Description

InstanceCustomIndexKHR - Custom index associated with an intersected
instance

Description

InstanceCustomIndexKHR
A variable decorated with the InstanceCustomIndexKHR decoration will
contain the application-defined value of the instance that intersects
the current ray. This variable contains the value that was specified in
VkAccelerationStructureInstanceKHR
:: instanceCustomIndex for the current acceleration structure
instance in the lower 24 bits and the upper 8 bits will be zero.

Valid Usage

• 
  
  VUID-InstanceCustomIndexKHR-InstanceCustomIndexKHR-04251
  The InstanceCustomIndexKHR decoration must be used only within
  the IntersectionKHR , AnyHitKHR , or ClosestHitKHR
Execution Model

• 
  
  VUID-InstanceCustomIndexKHR-InstanceCustomIndexKHR-04252
  The variable decorated with InstanceCustomIndexKHR must be
  declared using the Input Storage Class

• 
  
  VUID-InstanceCustomIndexKHR-InstanceCustomIndexKHR-04253
  The variable decorated with InstanceCustomIndexKHR must be
  declared as a scalar 32-bit integer value

Test Case(s)

Example 1

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

export uint fn() {
    return InstanceID();
}

SPIRV Example(s):

Example 2

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

[shader("intersection")]
void fn() {
uint 	ret = InstanceID();
}

HLSL:

The user-provided identifier for the instance on the bottom-level acceleration structure instance within the top-level structure.

Syntax

uint InstanceID();

Remarks

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

• Any Hit Shader
• Closest Hit Shader
• Intersection Shader

See also

Direct3D 12 Raytracing HLSL Reference

[farzonl]

@EugeneZelenko These bugs were created via automation. There are going to be about 160+ of these coming in. This first run was just a test. Would you like me to add the metabug label to all the issues created by the bot?

[EugeneZelenko]

@farzonl: metabug label should be used for issues that are used for tracking multiple issues, so bot could apply the label to such issues.

[farzonl]

@EugeneZelenko This is the list of bugs we are going to be adding to llvm-project next week: please let me know if you see something glaring that would be painful for you: farzonl/test_repo#157

[EugeneZelenko]

@farzonl: This is good example of metabug :-) But I did not look on each issue. Some of them may be of metabug kind.