带Protobuf的C++程序编译为WASM后无法用Wasmtime运行的问题咨询

我尝试用Emscripten将基于Protobuf的C++程序编译为WASM，但编译成功后，既无法用Wasmtime运行，也无法用wasm2wat转换为.wat格式。

具体错误信息 #

1. Wasmtime运行报错 #

# wasmtime person.wasm
Error: failed to run main module `person.wasm`

Caused by:
    0: if you're trying to run a precompiled module, pass --allow-precompiled
    1: failed to compile wasm function 79 at offset 0x293c
    2: WebAssembly translation error
    3: Invalid input WebAssembly code at offset 10632: threads support is not enabled

2. wasm2wat转换报错 #

# wasm2wat person.wasm
000298a: error: unexpected opcode: 0xfe 0x10

文件目录结构 #

protobuf_wasm_test/
  -lib/
    -libprotobuf-lite.a
    -libprotobuf.a
    -libprotoc.a
  -pb/
    -person.pb.cc
    -person.pb.h
  -CMakeLists.txt
  -person.cpp

相关文件内容 #

pb/person.proto #

syntax = "proto3";
message Person {
    string id = 1;
    string name = 2;
}

person.cpp #

#include <iostream>
#include "./pb/person.pb.h"

int main()
{
    Person *person = (Person*)malloc(sizeof(Person));
    person->set_id("12345");
    person->set_name("abc");
    std::cout<<"id: "<<person->id()<<", name: "<<person->name()<<std::endl;
    free(person);
    return 0;
}

CMakeLists.txt #

cmake_minimum_required(VERSION 3.5)
project(protobuf_wasm_test)

add_compile_options(-sSTANDALONE_WASM -Wno-unused-command-line-argument)

include_directories("${CMAKE_CURRENT_BINARY_DIR}/../pb")
include_directories("/home/hzb/protobuf_wasm/protobuf_src/src")

link_directories("${CMAKE_CURRENT_BINARY_DIR}/../lib")


set(proto_srcs "${CMAKE_CURRENT_BINARY_DIR}/../pb/person.pb.cc")
set(proto_hdrs "${CMAKE_CURRENT_BINARY_DIR}/../pb/person.pb.h")

add_library(proto
    ${proto_srcs}
    ${proto_hdrs})


add_executable(person
    person.cpp)

target_link_libraries(person
    proto
    protobuf)

编译过程 #

我已用Emscripten重新编译Protobuf源码，生成libprotobuf.a存于./lib/目录，编译命令及日志如下：

编译命令 #

emcmake ..
emmake make

编译日志 #

configure: cmake .. -DCMAKE_TOOLCHAIN_FILE=/home/hzb/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -DCMAKE_CROSSCOMPILING_EMULATOR=/home/hzb/emsdk/node/14.18.2_64bit/bin/node;--experimental-wasm-bulk-memory;--experimental-wasm-threads
-- Configuring done
-- Generating done
-- Build files have been written to: /home/hzb/protobuf_wasm/protobuf_wasm_test/build
make: make
[ 25%] Building CXX object CMakeFiles/proto.dir/pb/person.pb.cc.o
[ 50%] Linking CXX static library libproto.a
[ 50%] Built target proto
[ 75%] Building CXX object CMakeFiles/person.dir/person.cpp.o
[100%] Linking CXX executable person.js
[100%] Built target person

额外疑问 #

如何将包含第三方库的复杂C++程序编译为WASM并在Wasmtime等非Web WASM运行时运行？将每个库编译为WASM静态库（libxxx.a）后再链接到目标程序是否可行？

内容的提问来源于stack exchange，提问作者Han