More Tools To Create WASM Application

Use clang compiler

The recommended method to build a WASM binary is to use clang compiler clang-8. You can refer to apt.llvm.org for the detailed instructions. Here are referenced steps to install clang-8 in Ubuntu 16.04 and Ubuntu 18.04.

(1) Add source to your system source list from llvm website

For Ubuntu 16.04, add the following lines to /etc/apt/sources.list:

deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial main
deb-src http://apt.llvm.org/xenial/ llvm-toolchain-xenial main
# 8
deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main
deb-src http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main
# 9
deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main
deb-src http://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main

For Ubuntu 18.04, add the following lines to /etc/apt/sources.list:

# i386 not available
deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic main
deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic main
# 8
deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-8 main
deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic-8 main
# 9
deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main
deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main

(2) Download and install clang-8 tool-chain using following commands:

sudo wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
# Fingerprint: 6084 F3CF 814B 57C1 CF12 EFD5 15CF 4D18 AF4F 7421
sudo apt-get update
sudo apt-get install llvm-8 lld-8 clang-8

(3) Create a soft link under /usr/bin:

cd /usr/bin
sudo ln -s wasm-ld-8 wasm-ld

(4) Use the clang-8 command below to build the WASM C source code into the WASM binary.

clang-8 --target=wasm32 -O3 \
        -z stack-size=4096 -Wl,--initial-memory=65536 \
        -Wl,--allow-undefined,--export=main \
        -Wl,--strip-all,--no-entry -nostdlib \
        -o test.wasm test.c

You will get test.wasm which is the WASM app binary.

Using Docker

Another method available is using Docker. We assume you've already configured Docker (see Platform section above) and have a running interactive shell. Currently the Dockerfile only supports compiling apps with clang, with Emscripten planned for the future.

Use the clang-8 command below to build the WASM C source code into the WASM binary.

clang-8 --target=wasm32 -O3 \
        -z stack-size=4096 -Wl,--initial-memory=65536 \
        -Wl,--allow-undefined,--export=main \
        -Wl,--strip-all,--no-entry -nostdlib \
        -o test.wasm test.c

You will get test.wasm which is the WASM app binary.