Divergence analysis for GPU programs

[oota-llvm.git] / include / llvm / Analysis / TargetTransformInfo.h

diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index fdb20106a21b6557d418c9451df4cdeff6cd6972..1a7f6f6cfc04fdb55a50f6929154e91a57346854 100644 (file)
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -190,12 +190,21 @@ public:
   /// comments for a detailed explanation of the cost values.
   unsigned getUserCost(const User *U) const;
 
-  /// \brief hasBranchDivergence - Return true if branch divergence exists.
+  /// \brief Return true if branch divergence exists.
+  ///
   /// Branch divergence has a significantly negative impact on GPU performance
   /// when threads in the same wavefront take different paths due to conditional
   /// branches.
   bool hasBranchDivergence() const;
 
+  /// \brief Returns whether V is a source of divergence.
+  ///
+  /// This function provides the target-dependent information for
+  /// the target-independent DivergenceAnalysis. DivergenceAnalysis first
+  /// builds the dependency graph, and then runs the reachability algorithm
+  /// starting with the sources of divergence.
+  bool isSourceOfDivergence(const Value *V) const;
+
   /// \brief Test whether calls to a function lower to actual program function
   /// calls.
   ///
@@ -520,6 +529,7 @@ public:
                                     ArrayRef<const Value *> Arguments) = 0;
   virtual unsigned getUserCost(const User *U) = 0;
   virtual bool hasBranchDivergence() = 0;
+  virtual bool isSourceOfDivergence(const Value *V) = 0;
   virtual bool isLoweredToCall(const Function *F) = 0;
   virtual void getUnrollingPreferences(Loop *L, UnrollingPreferences &UP) = 0;
   virtual bool isLegalAddImmediate(int64_t Imm) = 0;
@@ -619,6 +629,9 @@ public:
   }
   unsigned getUserCost(const User *U) override { return Impl.getUserCost(U); }
   bool hasBranchDivergence() override { return Impl.hasBranchDivergence(); }
+  bool isSourceOfDivergence(const Value *V) override {
+    return Impl.isSourceOfDivergence(V);
+  }
   bool isLoweredToCall(const Function *F) override {
     return Impl.isLoweredToCall(F);
   }