| //===- llvm/Analysis/DivergenceAnalysis.h - Divergence Analysis -*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // The divergence analysis is an LLVM pass which can be used to find out |
| // if a branch instruction in a GPU program is divergent or not. It can help |
| // branch optimizations such as jump threading and loop unswitching to make |
| // better decisions. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/Pass.h" |
| |
| namespace llvm { |
| class Value; |
| class DivergenceAnalysis : public FunctionPass { |
| public: |
| static char ID; |
| |
| DivergenceAnalysis() : FunctionPass(ID) { |
| initializeDivergenceAnalysisPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| bool runOnFunction(Function &F) override; |
| |
| // Print all divergent branches in the function. |
| void print(raw_ostream &OS, const Module *) const override; |
| |
| // Returns true if V is divergent. |
| bool isDivergent(const Value *V) const { return DivergentValues.count(V); } |
| |
| // Returns true if V is uniform/non-divergent. |
| bool isUniform(const Value *V) const { return !isDivergent(V); } |
| |
| private: |
| // Stores all divergent values. |
| DenseSet<const Value *> DivergentValues; |
| }; |
| } // End llvm namespace |