[DivergenceAnalysis] Separated definition of class into header.

The definition of the DivergenceAnalysis pass was in a CPP
file and wasn't accessible to users of the analysis to get it
through "getAnalysis<>()".
This patch extracts the definition into a separate header that
can be used by users of the analysis to fetch the results.

Patch by Volkan Keles (vkeles@apple.com)

llvm-svn: 248186

1 files changed, 48 insertions, 0 deletions

diff --git a/llvm/include/llvm/Analysis/DivergenceAnalysis.h b/llvm/include/llvm/Analysis/DivergenceAnalysis.h
new file mode 100644
index 00000000000..aa2de571ba1
--- /dev/null
+++ b/llvm/include/llvm/Analysis/DivergenceAnalysis.h
@@ -0,0 +1,48 @@
+//===- 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