ARM: fix yet another stack-folding bug

We were trying to fold the stack adjustment into the wrong instruction in the
situation where the entire basic-block was epilogue code. Really, it can only
ever be valid to do the folding precisely where the "add sp, ..." would be
placed so there's no need for a separate iterator to track that.

Should fix PR18136.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196493 91177308-0d34-0410-b5e6-96231b3b80d8
[mips][msa] Fix issue with immediate fields of LD/ST instructions
not being correctly encoded/decoded.
In more detail, immediate fields of LD/ST instructions should be
divided/multiplied by the size of the data format before encoding and
after decoding, respectively.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196494 91177308-0d34-0410-b5e6-96231b3b80d8