6 files changed, 46 insertions, 0 deletions
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfo.h b/llvm/include/llvm/Analysis/TargetTransformInfo.h
index a769d5f67dd..ee40a36ccaf 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfo.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfo.h
@@ -753,6 +753,9 @@ public:
   bool useReductionIntrinsic(unsigned Opcode, Type *Ty,
                              ReductionFlags Flags) const;
 
+  /// \returns True if the target wants to expand the given reduction intrinsic
+  /// into a shuffle sequence.
+  bool shouldExpandReduction(const IntrinsicInst *II) const;
   /// @}
 
 private:
@@ -910,6 +913,7 @@ public:
                                         VectorType *VecTy) const = 0;
   virtual bool useReductionIntrinsic(unsigned Opcode, Type *Ty,
                                      ReductionFlags) const = 0;
+  virtual bool shouldExpandReduction(const IntrinsicInst *II) const = 0;
 };
 
 template <typename T>
@@ -1219,6 +1223,9 @@ public:
                              ReductionFlags Flags) const override {
     return Impl.useReductionIntrinsic(Opcode, Ty, Flags);
   }
+  bool shouldExpandReduction(const IntrinsicInst *II) const override {
+    return Impl.shouldExpandReduction(II);
+  }
 };
 
 template <typename T>
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
index 83b975e94f6..1760dbf2548 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -462,6 +462,10 @@ public:
     return false;
   }
 
+  bool shouldExpandReduction(const IntrinsicInst *II) const {
+    return true;
+  }
+
 protected:
   // Obtain the minimum required size to hold the value (without the sign)
   // In case of a vector it returns the min required size for one element.
diff --git a/llvm/include/llvm/CodeGen/ExpandReductions.h b/llvm/include/llvm/CodeGen/ExpandReductions.h
new file mode 100644
index 00000000000..c6aaaad967b
--- /dev/null
+++ b/llvm/include/llvm/CodeGen/ExpandReductions.h
@@ -0,0 +1,24 @@
+//===----- ExpandReductions.h - Expand experimental reduction intrinsics --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_EXPANDREDUCTIONS_H
+#define LLVM_CODEGEN_EXPANDREDUCTIONS_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class ExpandReductionsPass
+    : public PassInfoMixin<ExpandReductionsPass> {
+public:
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_EXPANDREDUCTIONS_H
diff --git a/llvm/include/llvm/CodeGen/Passes.h b/llvm/include/llvm/CodeGen/Passes.h
index 42299b52941..811dc5f78a5 100644
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -405,6 +405,10 @@ namespace llvm {
   /// printing assembly.
   ModulePass *createMachineOutlinerPass();
 
+  /// This pass expands the experimental reduction intrinsics into sequences of
+  /// shuffles.
+  FunctionPass *createExpandReductionsPass();
+
 } // End llvm namespace
 
 /// Target machine pass initializer for passes with dependencies. Use with
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index aae84ffd851..7ee0f678197 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -130,6 +130,7 @@ void initializeEfficiencySanitizerPass(PassRegistry&);
 void initializeEliminateAvailableExternallyLegacyPassPass(PassRegistry&);
 void initializeExpandISelPseudosPass(PassRegistry&);
 void initializeExpandPostRAPass(PassRegistry&);
+void initializeExpandReductionsPass(PassRegistry&);
 void initializeExternalAAWrapperPassPass(PassRegistry&);
 void initializeFEntryInserterPass(PassRegistry&);
 void initializeFinalizeMachineBundlesPass(PassRegistry&);
diff --git a/llvm/include/llvm/Transforms/Utils/LoopUtils.h b/llvm/include/llvm/Transforms/Utils/LoopUtils.h
index 94d10c98eb0..561f9488062 100644
--- a/llvm/include/llvm/Transforms/Utils/LoopUtils.h
+++ b/llvm/include/llvm/Transforms/Utils/LoopUtils.h
@@ -491,6 +491,12 @@ bool canSinkOrHoistInst(Instruction &I, AAResults *AA, DominatorTree *DT,
                         LoopSafetyInfo *SafetyInfo,
                         OptimizationRemarkEmitter *ORE = nullptr);
 
+/// Generates a vector reduction using shufflevectors to reduce the value.
+Value *getShuffleReduction(IRBuilder<> &Builder, Value *Src, unsigned Op,
+                           RecurrenceDescriptor::MinMaxRecurrenceKind
+                               MinMaxKind = RecurrenceDescriptor::MRK_Invalid,
+                           ArrayRef<Value *> RedOps = ArrayRef<Value *>());
+
 /// Create a target reduction of the given vector. The reduction operation
 /// is described by the \p Opcode parameter. min/max reductions require
 /// additional information supplied in \p Flags.