[RISCV] Separate the analysis part of RISCVInsertVSETVLI.

This analysis can be reused in other places.
Also, moved some utility functions into RISCVInstrInfo.

Author: Mikhail Gudim

llvm/lib/Target/RISCV/CMakeLists.txt

@@ -65,6 +65,7 @@ add_llvm_target(RISCVCodeGen
   RISCVTargetMachine.cpp
   RISCVTargetObjectFile.cpp
   RISCVTargetTransformInfo.cpp
+  RISCVVConfigAnalysis.cpp
   RISCVVectorMaskDAGMutation.cpp
   RISCVVectorPeephole.cpp
   RISCVVLOptimizer.cpp

llvm/lib/Target/RISCV/RISCV.h

@@ -111,6 +111,8 @@ void initializeRISCVO0PreLegalizerCombinerPass(PassRegistry &);
 FunctionPass *createRISCVPreLegalizerCombiner();
 void initializeRISCVPreLegalizerCombinerPass(PassRegistry &);
 
+void initializeRISCVVConfigWrapperPassPass(PassRegistry &);
+
 FunctionPass *createRISCVVLOptimizerPass();
 void initializeRISCVVLOptimizerPass(PassRegistry &);