This patch adds system registers for controlling aspects of SVE:
- ZCR_EL1 (r/w) visible at EL1 and EL0.
- ZCR_EL2 (r/w) visible at EL2 and Non-secure EL1 and EL0.
- ZCR_EL3 (r/w) visible at all exception levels.
and a system register identifying SVE:
- ID_AA64ZFR0_EL1 (r) SVE Feature identifier.
Reviewers: SjoerdMeijer, samparker, pbarrio, fhahn, javed.absar
Reviewed By: SjoerdMeijer
Differential Revision: https://reviews.llvm.org/D50885
llvm-svn: 340158