Introduction to Emscripten
Explore how Emscripten converts C/C++ code into WebAssembly modules using Clang and LLVM. Understand the role of emsdk in managing toolchains, generate asm.js for Node.js and browsers, and learn about optimization techniques to improve WebAssembly performance.
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Overview
In this chapter, we’ll learn about Emscripten, which is a toolchain to convert C/C++ code into a WebAssembly module.
Emscripten consists of two components:
- Emscripten compiler frontend
- Emscripten SDK (emsdk)
The Clang compiler frontend compiles C/C++ code into LLVM intermediate representation (LLVM IR) and then uses the LLVM backend to convert the LLVM IR into native code. The Clang compiler is fast, uses little memory, and is compatible with GNU Compiler Collection (GCC). Emscripten is similar to Clang; the former produces a wasm binary while the latter produces a native binary. The Emscripten compiler frontend (emcc) is the compiler frontend that converts C/C++ into LLVM IR (both binary and human-readable form) and into the WebAssembly binary or asm.js, such as JavaScript.
The Emscripten SDK, or emsdk, helps manage and maintain the Emscripten toolchain components and set up the runtime/terminal environment to run emcc.
In this chapter, we’ll learn how to install Emscripten. Then, we’ll use Emscripten to generate asm.js, a WebAssembly module that runs on Node.js and the browser. After that, we’ll explore the emsdk tool. Finally, we’ll explore various optimizations provided by Emscripten.
Did You Know?
asm.js is a subset of JavaScript that is optimized to run at near-native performance in the browser. The asm.js spec was not accepted by all browser vendors. asm.js has evolved into WebAssembly.