Merge pull request #24876 from 1e100:master

PiperOrigin-RevId: 236012087

tensorflow/lite/g3doc/devguide.md

@@ -215,11 +215,14 @@ trained Tensorflow models to the
 devices. To use the converter, refer to the
 [Tensorflow-CoreML converter documentation](https://github.com/tf-coreml/tf-coreml).
 
-### Raspberry Pi
+### ARM32 and ARM64 Linux
 
 Compile Tensorflow Lite for a Raspberry Pi by following the
-[RPi build instructions](rpi.md) This compiles a static library file (`.a`) used
-to build your app. There are plans for Python bindings and a demo app.
+[RPi build instructions](rpi.md) Compile Tensorflow Lite for a generic aarch64
+board such as Odroid C2, Pine64, NanoPi, and others by following the
+[ARM64 Linux build instructions](linux_aarch64.md) This compiles a static
+library file (`.a`) used to build your app. There are plans for Python bindings
+and a demo app.
 
 ## 4. Optimize your model (optional)
 

tensorflow/lite/g3doc/linux_aarch64.md

@@ -0,0 +1,62 @@
+# TensorFlow Lite for generic ARM64 boards
+
+## Cross compiling
+
+### Installing the toolchain
+
+```bash
+sudo apt-get update
+sudo apt-get install crossbuild-essential-arm64
+```
+
+> If you are using Docker, you may not use `sudo`.
+
+### Building
+
+Clone this Tensorflow repository. Run this script at the root of the repository
+to download all the dependencies:
+
+> The Tensorflow repository is in `/tensorflow` if you are using
+> `tensorflow/tensorflow:nightly-devel` docker image, just try it.
+
+```bash
+./tensorflow/lite/tools/make/download_dependencies.sh
+```
+
+Note that you only need to do this once.
+
+Compile:
+
+```bash
+./tensorflow/lite/tools/make/build_aarch64_lib.sh
+```
+
+This should compile a static library in:
+`tensorflow/lite/gen/gen/aarch64_armv8-a/lib/libtensorflow-lite.a`.
+
+## Native compiling
+
+These steps were tested on HardKernel Odroid C2, gcc version 5.4.0.
+
+Log in to your board, install the toolchain.
+
+```bash
+sudo apt-get install build-essential
+```
+
+First, clone the TensorFlow repository. Run this at the root of the repository:
+
+```bash
+./tensorflow/lite/tools/make/download_dependencies.sh
+```
+
+Note that you only need to do this once.
+
+Compile:
+
+```bash
+./tensorflow/lite/tools/make/build_aarch64_lib.sh
+```
+
+This should compile a static library in:
+`tensorflow/lite/gen/gen/aarch64_armv8-a/lib/libtensorflow-lite.a`.

tensorflow/lite/tools/make/Makefile

@@ -1,3 +1,7 @@
+# Make uses /bin/sh by default, which is incompatible with the bashisms seen
+# below.
+SHELL := /bin/bash
+
 # Find where we're running from, so we can store generated files here.
 ifeq ($(origin MAKEFILE_DIR), undefined)
 	MAKEFILE_DIR := $(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))

tensorflow/lite/tools/make/build_aarch64_lib.sh

@@ -0,0 +1,22 @@
+#!/bin/bash -x
+# Copyright 2017 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.
+# ==============================================================================
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR/../../../.."
+
+CC_PREFIX=aarch64-linux-gnu- make -j 3 -f tensorflow/lite/tools/make/Makefile TARGET=aarch64 TARGET_ARCH=armv8-a

tensorflow/lite/tools/make/targets/aarch64_makefile.inc

@@ -0,0 +1,33 @@
+# Settings for generic aarch64 boards such as Odroid C2 or Pine64.
+ifeq ($(TARGET),aarch64)
+  # The aarch64 architecture covers all 64-bit ARM chips. This arch mandates
+  # NEON, so FPU flags are not needed below.
+  TARGET_ARCH := armv8-a
+  TARGET_TOOLCHAIN_PREFIX := aarch64-linux-gnu-
+
+  CXXFLAGS += \
+    -march=armv8-a \
+    -funsafe-math-optimizations \
+    -ftree-vectorize \
+    -fPIC
+
+  CCFLAGS += \
+    -march=armv8-a \
+    -funsafe-math-optimizations \
+    -ftree-vectorize \
+    -fPIC
+
+  LDFLAGS := \
+    -Wl,--no-export-dynamic \
+    -Wl,--exclude-libs,ALL \
+    -Wl,--gc-sections \
+    -Wl,--as-needed
+
+       
+  LIBS := \
+    -lstdc++ \
+    -lpthread \
+    -lm \
+    -ldl
+
+endif