Update sample workload wasm-av1 and add workload XNNPACK (#443)

samples/workload/XNNPACK/README.md

@@ -0,0 +1,60 @@
+"XNNPACK" sample introduction
+==============
+This sample demonstrates how to build [XNNPACK](https://github.com/google/XNNPACK) benchmarks into WebAssembly with emcc toolchain and run them with iwasm.
+
+## Installation toolchains
+
+- **bazel**. Please install bazel from [latest release](https://github.com/bazelbuild/bazel/releases)
+
+- **emsdk**. Please install [emsdk](https://github.com/emscripten-core/emsdk) to /opt/emsdk:
+```bash
+cd /opt
+git clone https://github.com/emscripten-core/emsdk.git
+cd emsdk
+./emsdk install latest
+./emsdk activate latest
+```
+And set up ensdk environment:
+```bash
+source /opt/emsdk/emsdk_env.sh
+```
+
+## Build XNNPACK
+
+```bash
+cd <wamr-dir>/samples/workload/XNNPACK
+mkdir build
+cd build
+cmake ..
+```
+The wasm files are generated under folder samples/workload/XNNPACK/xnnpack/bazel-bin.
+
+## Run benchmarks
+
+Firstly please build iwasm with simd, libc-emcc and lib-pthread support:
+
+``` bash
+$ cd <wamr-dir>/product-mini/platforms/linux/
+$ mkdir build && cd build
+$ cmake .. -DWAMR_BUILD_SIMD=1 -DWAMR_BUILD_LIBC_EMCC=1 -DWAMR_BUILD_LIB_PTHREAD=1
+$ make
+```
+
+And please build wamrc:
+
+``` bash
+cd <wamr-dir>/wamr-compiler
+./build_llvm.sh
+mkdir build && cd build
+cmake ..
+make
+```
+
+Then compile wasm file to aot file and run:
+
+``` shell
+$ cd <wamr-dir>/samples/workload/XNNPACK/xnnpack/bazel-bin
+$ wamrc --enable-simd -o average_pooling_bench.aot average_pooling_bench.wasm  (or other wasm files)
+$ iwasm average_pooling_bench.aot
+```
+