ARM: Negative offset support problem

This patch is to permit a negative offset usage for a non frame access.

Patch by Igor Oblakov.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217431 91177308-0d34-0410-b5e6-96231b3b80d8
[mips] Add assembler support for .set push/pop directive.

Summary:
These directives are used to save the current assembler options (in the case of ".set push") and restore the previously saved options (in the case of ".set pop").

Contains work done by Matheus Almeida.

Reviewers: dsanders

Reviewed By: dsanders

Differential Revision: http://reviews.llvm.org/D4821

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217432 91177308-0d34-0410-b5e6-96231b3b80d8