VPlan + RV
This is the LLVM fork of the VPlan+RV project, a joint effort by Saarland University and Intel. The aim of the VPlan+RV project is to bring functionality of RV, the Region Vectorizer, to LLVM. The project was first presented at the US LLVM Developers' Meeting in 2017.
A new DivergenceAnalysis
VPlan+RV includes a new divergence analysis that can be used in the LoopVectorizer and as a replacement for the existing DivergenceAnalysis. This new DivergenceAnalysis supports unstructured, reducible control flow and has a statically-precise notion of sync dependence.
Divergence Analysis for GPU kernels (GPUDivergenceAnalysis)
Pass -use-rv-da to opt and the existing DivergenceAnalysis pass will turn into a wrapper for the new DivergenceAnalysis.
In that mode, all divergence queries in the LLVM code base will be handled by the new implementation (AMDGPU, NVPTX, StructurizeCFG, ...).
Divergence Analysis for LoopVectorizer (LoopDivergenceAnalysis)
The tests (test/Analysis/DivergenceAnalysis/Loops) show some divergence queries that will occur once outer-loop vectorization is supported by LLVM.