They promised to release source in August and they seem to have worked hard to make the deadline. But they're following the "throw code over the wall" open source model, with important parts yet to be released. The compiler toolchain so far only supports compiling some Java samples, full support for Java and JavaScript will only be coming later.

From the readme: https://code.opensource.huaweicloud.com/HarmonyOS/OpenArkCom...

开源计划

编译器框架代码开源

时间：2019年8月

开源范围：编译器IR+中端语言实现

开放能力：

框架开源供参考学习，了解方舟编译器架构及框架代码

开发者可构建出完整编译器工具链，支持Java Sample程序编译（非应用）

后续开源范围

陆续开源编译器前端、后端、编译优化；完整支持Java程序编译、JavaScript语言应用的编译等。

计划持续更新...

EDIT: since most readers on HN probably can't read Chinese, you might be interested in the documentation for the intermediate representation, which is in English: https://code.opensource.huaweicloud.com/HarmonyOS/OpenArkCom...

The website wouldn't load for me on Firefox (android and linux) but did load on chrome on linux...