静态博客程序emscripten

 

Download and install

Note

You can also build Emscripten from source if you prefer that to downloading binaries using the emsdk.

Tip

if you’d like to install emscripten using the unofficial packages instead of the officially supported emsdk, see the bottom of the page.

Installation instructions using the emsdk (recommended)

First check the Platform-specific notes below and install any prerequisites.

The core Emscripten SDK (emsdk) driver is a Python script. You can get it for the first time with

# Get the emsdk repo
git clone https://github.com/emscripten-core/emsdk

# Enter that directory
cd emsdk

Note

You can also get the emsdk without git, by selecting “Clone or download => Download ZIP” on the emsdk GitHub page.

Run the following emsdk commands to get the latest tools from GitHub and set them as active:

# Fetch the latest version of the emsdk (not needed the first time you clone)
git pull

# Download and install the latest SDK tools.
./emsdk install latest

# Make the "latest" SDK "active" for the current user. (writes .emscripten file)
./emsdk activate latest

# Activate PATH and other environment variables in the current terminal
source ./emsdk_env.sh

Note

On Windows, run emsdk.bat instead of ./emsdk, and emsdk_env.bat instead of source ./emsdk_env.sh.

Note

On Windows, if you use the activate command, the step of emsdk_env.bat is optional. If you want to know more, see activate SDK version.

Note

git pull will fetch the current list of tags, but very recent ones may not yet be present there. You can run ./emsdk update-tags to update the list of tags directly.

If you change the location of the SDK (e.g. take it to another computer on an USB), re-run the ./emsdk activate latest and source ./emsdk_env.sh commands.

Emsdk install targets

In the description above we asked the emsdk to install and activate latest, which is the latest tagged release. That is often what you want.

You can also install a specific version by specifying it, for example,

./emsdk install 1.38.45

Note

When installing old versions from before the build infrastructure rewrite (anything before 1.38.33), you need to write something like ./emsdk install sdk-1.38.20-64bit (add sdk- and -64bit) as that was the naming convention at the time.

There are also “tip-of-tree builds”, which are the very latest code that passes integration tests on Chromium CI. This is updated much more frequently than tagged releases, but may be less stable (we tag releases manually using a more careful procedure). Tip-of-tree builds may be useful for continuous integration that uses the emsdk (as Emscripten’s GitHub CI does), and you may want to use it in your own CI as well, so that if you find a regression on your project you can report it and prevent it from reaching a tagged release. Tip-of-builds may also be useful if you want to test a feature that just landed but didn’t reach a release yet. To use a tip-of-tree build, use the tot target, and note that you must specify the backend explicitly,

# Get a tip-of-tree
./emsdk install tot

(In the above examples we installed the various targets; remember to also activate them as in the full example from earlier.)

Platform-specific notes

Windows

1. Install Python 3.6 or newer (older versions may not work due to a GitHub change with SSL).

Note

Instead of running emscripten on Windows directly, you can use the Windows Subsystem for Linux to run it in a Linux environment.

macOS

Note

Emscripten requires macOS 10.14 Mojave or above.

If you use the Emscripten SDK it includes a bundled version of Python 3. Otherwise you will need to manually install and use Python 3.6 or newer.

These instructions explain how to install all the required tools. You can test whether some of these are already installed on the platform and skip those steps.

1. Install the Xcode Command Line Tools. These are a precondition for git.

• Install Xcode from the macOS App Store.

• In Xcode | Preferences | Downloads, install Command Line Tools.

1. Install git:

• Make sure the OS allows installing git.

• Install Xcode and the Xcode Command Line Tools (should already have been done). This will provide git to the system PATH (see this stackoverflow post).

• Download and install git directly from http://git-scm.com/.

1. Install cmake if you do not have it yet:

• Download and install latest CMake from Kitware CMake downloads.

Linux

Note

Emsdk does not install any tools to the system, or otherwise interact with Linux package managers. All file changes are done inside the emsdk/ directory.

• Python is not provided by emsdk. The user is expected to install this beforehand with the system package manager:

  # Install Python
  sudo apt-get install python3
  
  # Install CMake (optional, only needed for tests and building Binaryen or LLVM)
  sudo apt-get install cmake
  

Note

If you want to use your system’s Node.js instead of the emsdk’s, it may be node instead of nodejs, and you can adjust the NODE_JS attribute of your .emscripten file to point to it.

• Git is not installed automatically. Git is only needed if you want to use tools from a development branch.

  # Install git
  sudo apt-get install git
  

Verifying the installation

The easiest way to verify the installation is to compile some code using Emscripten.

You can jump ahead to the Emscripten Tutorial, but if you have any problems building you should run through the basic tests and troubleshooting instructions in Verifying the Emscripten Development Environment.

Updating the SDK

Tip

You only need to install the SDK once! After that you can update to the latest SDK at any time using Emscripten SDK (emsdk).

Type the following in a command prompt

# Fetch the latest registry of available tools.
./emsdk update

# Download and install the latest SDK tools.
./emsdk install latest

# Set up the compiler configuration to point to the "latest" SDK.
./emsdk activate latest

# Activate PATH and other environment variables in the current terminal
source ./emsdk_env.sh

The package manager can do many other maintenance tasks ranging from fetching specific old versions of the SDK through to using the versions of the tools on GitHub (or even your own fork). Check out all the possibilities in the “How to” guides.

from https://emscripten.org/docs/getting_started/downloads.html

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Building Emscripten from Source

Building Emscripten yourself is an alternative to getting binaries using the emsdk.

Emscripten itself is written in Python and JavaScript so it does not need to be compiled. However, after checkout you will need to perform various steps before it can be used (e.g. npm install). The bootstrap script in the top level of the repository takes care of running these steps and emcc will error out if it detects that bootstrap needs to be run.

In addition to the main emscripten repository you will also need to checkout and build LLVM and Binaryen (as detailed below). After compiling these, you will need to edit your .emscripten file to point to their corresponding locations.

Use the main branches of each of these repositories, or check the Packaging instructions to identify precise commits used in a specific release.

Building LLVM

Build LLVM from the git repo. Include clang and wasm-ld (using something like -DLLVM_ENABLE_PROJECTS='lld;clang') and the Wasm backend (which is included by default; just don’t disable it), following that project’s instructions. For example, something like this can work:

mkdir build
cd build/
cmake ../llvm -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS='lld;clang' -DLLVM_TARGETS_TO_BUILD="host;WebAssembly" -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_TESTS=OFF  # -DLLVM_ENABLE_ASSERTIONS=ON
cmake --build .

Then set the environment variable EM_LLVM_ROOT to <llvm_src>/build/bin (no need to install).

If you need to match the emsdk releases of LLVM, review the emscripten-release build and test scripts. Specifically src/build.py.

Please refer to the upstream docs for more detail.

Building Binaryen

See the Binaryen build instructions.

• Emscripten Toolchain Requirements
• Configuring Emscripten Settings when Manually Building from Source
• Verifying the Emscripten Development Environment

from https://emscripten.org/docs/building_from_source/index.html#installing-from-source

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https://emscripten.org/docs/getting_started/Tutorial.html

https://gitlab.com/pages/emscripten

https://github.com/emscripten-core/emscripten