From ef9dfee7bdc8e0d82c9b7ddf9414ef99d866d7ba Mon Sep 17 00:00:00 2001
From: Eugene Zhulenev <ezhulenev@google.com>
Date: Tue, 24 Sep 2019 12:52:45 -0700
Subject: Tensor block evaluation V2 support for unary/binary/broadcsting

---
 .../CXX11/src/Tensor/TensorForwardDeclarations.h   | 46 ++++++++++++++++++++--
 1 file changed, 42 insertions(+), 4 deletions(-)

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

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h b/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h
index 772dbbe35..f33489a33 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorForwardDeclarations.h
@@ -154,23 +154,61 @@ struct IsVectorizable<GpuDevice, Expression> {
                             TensorEvaluator<Expression, GpuDevice>::IsAligned;
 };
 
+// Tiled evaluation strategy.
+#if !EIGEN_HAS_CXX11
+// To be able to use `TiledEvaluation::Off` in C++03 we need a namespace.
+// (Use of enumeration in a nested name specifier is a c++11 extension).
+namespace TiledEvaluation {
+#endif
+enum TiledEvaluation {
+  Off = 0,    // tiled evaluation is not supported
+  On = 1,     // still work in progress (see TensorBlockV2.h)
+  Legacy = 2  // soon to be deprecated (see TensorBock.h)
+};
+#if !EIGEN_HAS_CXX11
+}   // namespace TiledEvaluation
+#endif
+
 template <typename Device, typename Expression>
 struct IsTileable {
+#if !EIGEN_HAS_CXX11
+  typedef TiledEvaluation::TiledEvaluation TiledEvaluation;
+#endif
+
   // Check that block evaluation is supported and it's a preferred option (at
   // least one sub-expression has much faster block evaluation, e.g.
   // broadcasting).
-  static const bool value = TensorEvaluator<Expression, Device>::BlockAccess &&
-                            TensorEvaluator<Expression, Device>::PreferBlockAccess;
+  static const bool BlockAccess =
+      TensorEvaluator<Expression, Device>::BlockAccess &&
+      TensorEvaluator<Expression, Device>::PreferBlockAccess;
+
+  static const bool BlockAccessV2 =
+      TensorEvaluator<Expression, Device>::BlockAccessV2 &&
+      TensorEvaluator<Expression, Device>::PreferBlockAccess;
+
+
+  static const TiledEvaluation value =
+      BlockAccessV2
+          ? TiledEvaluation::On
+          : (BlockAccess ? TiledEvaluation::Legacy : TiledEvaluation::Off);
 };
 
+#if EIGEN_HAS_CXX11
+template <typename Expression, typename Device,
+          bool Vectorizable      = IsVectorizable<Device, Expression>::value,
+          TiledEvaluation Tiling = IsTileable<Device, Expression>::value>
+class TensorExecutor;
+#else
 template <typename Expression, typename Device,
           bool Vectorizable = IsVectorizable<Device, Expression>::value,
-          bool Tileable = IsTileable<Device, Expression>::value>
+          TiledEvaluation::TiledEvaluation Tiling = IsTileable<Device, Expression>::value>
 class TensorExecutor;
+#endif
 
+// TODO(ezhulenev): Add TiledEvaluation support to async executor.
 template <typename Expression, typename Device, typename DoneCallback,
           bool Vectorizable = IsVectorizable<Device, Expression>::value,
-          bool Tileable = IsTileable<Device, Expression>::value>
+          bool Tileable     = IsTileable<Device, Expression>::BlockAccess>
 class TensorAsyncExecutor;
 
 }  // end namespace internal
-- 
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