Build xtensa for Vision P6.

Confirmed that all tests pass for vision P6:
```
make -f tensorflow/lite/micro/tools/make/Makefile TARGET=xtensa OPTIMIZED_KERNEL_DIR=xtensa TARGET_ARCH=vision_p6 XTENSA_CORE=P6_200528 test
```

tensorflow/lite/micro/kernels/BUILD

@@ -34,7 +34,9 @@ cc_library(
         ],
     }),
     copts = micro_copts(),
-    deps = select({
+    deps = [
+        ":xtensa",
+    ] + select({
         "//conditions:default": [],
         ":xtensa_hifimini": [
             #"//third_party/xtensa/cstub64s:hifi_mini",
@@ -62,6 +64,7 @@ cc_library(
     deps = [
         ":fixedpoint_utils",
         ":kernel_util",
+        ":xtensa",
         "//tensorflow/lite/c:common",
         "//tensorflow/lite/kernels:kernel_util",
         "//tensorflow/lite/kernels/internal:common",
@@ -162,6 +165,7 @@ cc_library(
         ":kernel_util",
         ":fixedpoint_utils",
         ":micro_utils",
+        ":xtensa",
         "//tensorflow/lite/c:common",
         "//tensorflow/lite/kernels:kernel_util",
         "//tensorflow/lite/kernels:op_macros",
@@ -183,6 +187,24 @@ cc_library(
     }),
 )
 
+cc_library(
+    name = "xtensa",
+    hdrs = select({
+        "//conditions:default": [
+        ],
+        ":xtensa_hifimini": [
+            "xtensa/xtensa.h",
+        ],
+    }),
+    copts = micro_copts(),
+    deps = select({
+        "//conditions:default": [],
+        ":xtensa_hifimini": [
+            #"//third_party/xtensa/cstub64s:hifi_mini",
+        ],
+    }),
+)
+
 test_suite(
     name = "all_tests",
 )

tensorflow/lite/micro/kernels/xtensa/conv.cc

@@ -13,20 +13,18 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#include "tensorflow/lite/kernels/internal/reference/conv.h"
-
-#include <xtensa/tie/xt_hifi2.h>
-
 #include "tensorflow/lite/c/builtin_op_data.h"
 #include "tensorflow/lite/c/common.h"
 #include "tensorflow/lite/kernels/internal/common.h"
 #include "tensorflow/lite/kernels/internal/quantization_util.h"
+#include "tensorflow/lite/kernels/internal/reference/conv.h"
 #include "tensorflow/lite/kernels/internal/reference/integer_ops/conv.h"
 #include "tensorflow/lite/kernels/internal/tensor_ctypes.h"
 #include "tensorflow/lite/kernels/kernel_util.h"
 #include "tensorflow/lite/kernels/padding.h"
 #include "tensorflow/lite/micro/kernels/kernel_util.h"
 #include "tensorflow/lite/micro/kernels/xtensa/fixedpoint_utils.h"
+#include "tensorflow/lite/micro/kernels/xtensa/xtensa.h"
 
 namespace tflite {
 namespace {

tensorflow/lite/micro/kernels/xtensa/depthwise_conv.cc

@@ -13,21 +13,19 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#include "tensorflow/lite/kernels/internal/reference/integer_ops/depthwise_conv.h"
-
-#include <xtensa/tie/xt_hifi2.h>
-
 #include "tensorflow/lite/c/builtin_op_data.h"
 #include "tensorflow/lite/c/common.h"
 #include "tensorflow/lite/kernels/internal/common.h"
 #include "tensorflow/lite/kernels/internal/quantization_util.h"
 #include "tensorflow/lite/kernels/internal/reference/depthwiseconv_float.h"
 #include "tensorflow/lite/kernels/internal/reference/depthwiseconv_uint8.h"
+#include "tensorflow/lite/kernels/internal/reference/integer_ops/depthwise_conv.h"
 #include "tensorflow/lite/kernels/internal/tensor_ctypes.h"
 #include "tensorflow/lite/kernels/kernel_util.h"
 #include "tensorflow/lite/kernels/padding.h"
 #include "tensorflow/lite/micro/kernels/kernel_util.h"
 #include "tensorflow/lite/micro/kernels/xtensa/fixedpoint_utils.h"
+#include "tensorflow/lite/micro/kernels/xtensa/xtensa.h"
 
 namespace tflite {
 namespace {

tensorflow/lite/micro/kernels/xtensa/fixedpoint_utils.h

@@ -16,16 +16,17 @@ limitations under the License.
 #ifndef TENSORFLOW_LITE_MICRO_KERNELS_XTENSA_HIFIMINI_FIXEDPOINT_UTILS_H_
 #define TENSORFLOW_LITE_MICRO_KERNELS_XTENSA_HIFIMINI_FIXEDPOINT_UTILS_H_
 
-#include <xtensa/tie/xt_hifi2.h>
-
 #include <algorithm>
 #include <cmath>
 #include <cstdint>
 
 #include "tensorflow/lite/kernels/internal/compatibility.h"
+#include "tensorflow/lite/micro/kernels/xtensa/xtensa.h"
 
 namespace tflite {
 
+#if defined(HIFIMINI)
+
 // INT24 MIN/MAX
 #define INT24_MIN -8388608
 #define INT24_MAX 8388607
@@ -132,6 +133,8 @@ inline int CreateQConstantForInt24(int integer_bits, float f) {
   return static_cast<int>(raw);
 }
 
+#endif  // defined(HIFIMINI)
+
 }  // namespace tflite
 
 #endif  // TENSORFLOW_LITE_MICRO_KERNELS_XTENSA_HIFIMINI_FIXEDPOINT_UTILS_H_

tensorflow/lite/micro/kernels/xtensa/fully_connected.cc

@@ -13,19 +13,17 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#include "tensorflow/lite/kernels/internal/reference/fully_connected.h"
-
-#include <xtensa/tie/xt_hifi2.h>
-
 #include "tensorflow/lite/c/builtin_op_data.h"
 #include "tensorflow/lite/c/common.h"
 #include "tensorflow/lite/kernels/internal/common.h"
 #include "tensorflow/lite/kernels/internal/quantization_util.h"
+#include "tensorflow/lite/kernels/internal/reference/fully_connected.h"
 #include "tensorflow/lite/kernels/internal/reference/integer_ops/fully_connected.h"
 #include "tensorflow/lite/kernels/internal/tensor_ctypes.h"
 #include "tensorflow/lite/kernels/kernel_util.h"
 #include "tensorflow/lite/micro/kernels/kernel_util.h"
 #include "tensorflow/lite/micro/kernels/xtensa/fixedpoint_utils.h"
+#include "tensorflow/lite/micro/kernels/xtensa/xtensa.h"
 
 namespace tflite {
 namespace {

tensorflow/lite/micro/kernels/xtensa/quantize.cc

@@ -13,8 +13,6 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#include <xtensa/tie/xt_hifi2.h>
-
 #include "tensorflow/lite/c/common.h"
 #include "tensorflow/lite/kernels/internal/quantization_util.h"
 #include "tensorflow/lite/kernels/internal/reference/quantize.h"
@@ -24,6 +22,7 @@ limitations under the License.
 #include "tensorflow/lite/micro/kernels/kernel_util.h"
 #include "tensorflow/lite/micro/kernels/quantize.h"
 #include "tensorflow/lite/micro/kernels/xtensa/fixedpoint_utils.h"
+#include "tensorflow/lite/micro/kernels/xtensa/xtensa.h"
 #include "tensorflow/lite/micro/micro_utils.h"
 
 namespace tflite {

tensorflow/lite/micro/kernels/xtensa/softmax.cc

@@ -13,12 +13,11 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#include "tensorflow/lite/kernels/internal/reference/softmax.h"
-
 #include "tensorflow/lite/c/builtin_op_data.h"
 #include "tensorflow/lite/c/common.h"
 #include "tensorflow/lite/kernels/internal/common.h"
 #include "tensorflow/lite/kernels/internal/quantization_util.h"
+#include "tensorflow/lite/kernels/internal/reference/softmax.h"
 #include "tensorflow/lite/kernels/internal/tensor_ctypes.h"
 #include "tensorflow/lite/kernels/kernel_util.h"
 #include "tensorflow/lite/kernels/op_macros.h"

tensorflow/lite/micro/kernels/xtensa/svdf.cc

@@ -13,10 +13,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#include "tensorflow/lite/micro/kernels/svdf.h"
-
-#include <math.h>
-#include <xtensa/tie/xt_hifi2.h>
+#include <cmath>
 
 #include "tensorflow/lite/c/builtin_op_data.h"
 #include "tensorflow/lite/c/common.h"
@@ -27,7 +24,9 @@ limitations under the License.
 #include "tensorflow/lite/kernels/op_macros.h"
 #include "tensorflow/lite/micro/kernels/activation_utils.h"
 #include "tensorflow/lite/micro/kernels/kernel_util.h"
+#include "tensorflow/lite/micro/kernels/svdf.h"
 #include "tensorflow/lite/micro/kernels/xtensa/fixedpoint_utils.h"
+#include "tensorflow/lite/micro/kernels/xtensa/xtensa.h"
 
 namespace tflite {
 namespace {

tensorflow/lite/micro/kernels/xtensa/xtensa.h

@@ -0,0 +1,23 @@
+/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#ifndef TENSORFLOW_LITE_MICRO_KERNELS_XTENSA_XTENSA_H_
+#define TENSORFLOW_LITE_MICRO_KERNELS_XTENSA_XTENSA_H_
+
+#if defined(HIFIMINI)
+#include <xtensa/tie/xt_hifi2.h>
+#endif
+
+#endif  // TENSORFLOW_LITE_MICRO_KERNELS_XTENSA_XTENSA_H_