From 235e83aba608cf3d94b033bfbf551f8c136a3fab Mon Sep 17 00:00:00 2001
From: Rasmus Munk Larsen <rmlarsen@google.com>
Date: Thu, 14 Apr 2016 13:57:35 -0700
Subject: Eigen cost model part 1. This implements a basic recursive framework
 to estimate the cost of evaluating tensor expressions.

---
 unsupported/Eigen/CXX11/src/Tensor/TensorReverse.h | 40 ++++++++++++++--------
 1 file changed, 26 insertions(+), 14 deletions(-)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorReverse.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorReverse.h b/unsupported/Eigen/CXX11/src/Tensor/TensorReverse.h
index 96d92038c..1a59cc8f7 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorReverse.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorReverse.h
@@ -104,6 +104,10 @@ struct TensorEvaluator<const TensorReverseOp<ReverseDimensions, ArgType>, Device
   typedef typename XprType::Index Index;
   static const int NumDims = internal::array_size<ReverseDimensions>::value;
   typedef DSizes<Index, NumDims> Dimensions;
+  typedef typename XprType::Scalar Scalar;
+  typedef typename XprType::CoeffReturnType CoeffReturnType;
+  typedef typename PacketType<CoeffReturnType, Device>::type PacketReturnType;
+  static const int PacketSize = internal::unpacket_traits<PacketReturnType>::size;
 
   enum {
     IsAligned = false,
@@ -135,10 +139,6 @@ struct TensorEvaluator<const TensorReverseOp<ReverseDimensions, ArgType>, Device
     }
   }
 
-  typedef typename XprType::Scalar Scalar;
-  typedef typename XprType::CoeffReturnType CoeffReturnType;
-  typedef typename PacketType<CoeffReturnType, Device>::type PacketReturnType;
-
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
   const Dimensions& dimensions() const { return m_dimensions; }
 
@@ -195,21 +195,33 @@ struct TensorEvaluator<const TensorReverseOp<ReverseDimensions, ArgType>, Device
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
   PacketReturnType packet(Index index) const
   {
-    const int packetSize = internal::unpacket_traits<PacketReturnType>::size;
-    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
-    eigen_assert(index+packetSize-1 < dimensions().TotalSize());
+    EIGEN_STATIC_ASSERT(PacketSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
+    eigen_assert(index+PacketSize-1 < dimensions().TotalSize());
 
     // TODO(ndjaitly): write a better packing routine that uses
     // local structure.
     EIGEN_ALIGN_MAX typename internal::remove_const<CoeffReturnType>::type
-                                                            values[packetSize];
-    for (int i = 0; i < packetSize; ++i) {
+                                                            values[PacketSize];
+    for (int i = 0; i < PacketSize; ++i) {
       values[i] = coeff(index+i);
     }
     PacketReturnType rslt = internal::pload<PacketReturnType>(values);
     return rslt;
   }
 
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorOpCost costPerCoeff(bool vectorized) const {
+    double compute_cost = NumDims * (2 * TensorOpCost::AddCost<Index>() +
+                                     2 * TensorOpCost::MulCost<Index>() +
+                                     TensorOpCost::DivCost<Index>());
+    for (int i = 0; i < NumDims; ++i) {
+      if (m_reverse[i]) {
+        compute_cost += 2 * TensorOpCost::AddCost<Index>();
+      }
+    }
+    return m_impl.costPerCoeff(vectorized) +
+           TensorOpCost(0, 0, compute_cost, false /* vectorized */, PacketSize);
+  }
+
   EIGEN_DEVICE_FUNC Scalar* data() const { return NULL; }
 
  protected:
@@ -246,6 +258,7 @@ struct TensorEvaluator<TensorReverseOp<ReverseDimensions, ArgType>, Device>
   typedef typename XprType::Scalar Scalar;
   typedef typename XprType::CoeffReturnType CoeffReturnType;
   typedef typename PacketType<CoeffReturnType, Device>::type PacketReturnType;
+  static const int PacketSize = internal::unpacket_traits<PacketReturnType>::size;
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
   const Dimensions& dimensions() const { return this->m_dimensions; }
@@ -256,14 +269,13 @@ struct TensorEvaluator<TensorReverseOp<ReverseDimensions, ArgType>, Device>
 
   template <int StoreMode> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
   void writePacket(Index index, const PacketReturnType& x) {
-    const int packetSize = internal::unpacket_traits<PacketReturnType>::size;
-    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
-    eigen_assert(index+packetSize-1 < dimensions().TotalSize());
+    EIGEN_STATIC_ASSERT(PacketSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
+    eigen_assert(index+PacketSize-1 < dimensions().TotalSize());
 
     // This code is pilfered from TensorMorphing.h
-    EIGEN_ALIGN_MAX CoeffReturnType values[packetSize];
+    EIGEN_ALIGN_MAX CoeffReturnType values[PacketSize];
     internal::pstore<CoeffReturnType, PacketReturnType>(values, x);
-    for (int i = 0; i < packetSize; ++i) {
+    for (int i = 0; i < PacketSize; ++i) {
       this->coeffRef(index+i) = values[i];
     }
   }
-- 
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