Runs well on arm64 for me. Tested on 4.0_pre1 and 3.5-r2. RESTRICT=test so haven't run the tests.
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=6a3b29c9a74907ad138c838d93ad2d4eba0df048 https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=675012d3f892c605b8f3e28cbaa23b396166d345