Summary: Reserving registers x1-7 is used to support CONFIG_ARM64_LSE_ATOMICS in Linux kernel. This change adds support for reserving registers x1 through x7.
Reviewers: javed.absar, efriedma, nickdesaulniers, srhines, phosek
Reviewed By: nickdesaulniers
Subscribers: manojgupta, jfb, cfe-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D48581
llvm-svn: 342100