This patch implements the SPIR-V lowering for the following HLSL
intrinsics:
- SampleBias
- SampleGrad
- SampleLevel
- SampleCmp
- SampleCmpLevelZero
It defines the required LLVM intrinsics in 'IntrinsicsDirectX.td' and
'IntrinsicsSPIRV.td'.
It updates 'SPIRVInstructionSelector.cpp' to handle the new intrinsics
and
generates the correct 'OpImageSample*' instructions with the required
operands
(Bias, Grad, Lod, ConstOffset, MinLod, etc.).
CodeGen tests are added to verify the implementation for images with
dimension 1D, 2D, 3D, and Cube.
Assisted-by: Gemini
e1d2ff6caf