Xcode 8.0 Release was released on 13 Sep 2016 and requires macOS 10.11.5+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_8/Xcode_8.xip.
Release notes are located at https://developer.apple.com/library/content/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW78.
The SDKs it contains are:
- iOS 14A345
- macOS 16A300
- tvOS 14T328
- watchOS 14S326
The compilers it contains are:
- clang 8.0.0 (Build 800.0.38)
- swift 3.0 (Build 800.0.46.2)
- LLVM-GCC 3.9.0 (Build )