Bit late to mention it here, but GCC Explorer now supports GCC 5.1, and in fact has done since the day it was released!
GCC 5.1 has a bunch of link-time optimizations that aren’t well-demonstrated by GCC Explorer, so I’m going to have to revamp it a little. Watch this space!
Matt Godbolt is a C++ developer living in Chicago. He works for Hudson River Trading on super fun but secret things. He is one half of the Two's Complement podcast. Follow him on Mastodon or Bluesky.