This patch adds support for FPINST/FPINST2 as operands to vmsr/vmrs. These are optional registers that may be supported some ARM implementations to aid with resolution of floating point exceptions. The manual pages for vmsr and vmrs do not detail their use. Encodings and other information can be found in ARM Architecture Reference Manual section F, chapter 6, paragraph 3.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183733 91177308-0d34-0410-b5e6-96231b3b80d8
It adds support for negative zero offsets for loads and stores.
Negative zero is returned by the primary expression parser as INT32_MIN, so all that the method needs to do is to accept this value.
Behavior already present for Thumb2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183734 91177308-0d34-0410-b5e6-96231b3b80d8