R600/SI: Add some mubuf testcases.

I noticed some odd looking cases where addr64 wasn't set
when storing to a pointer in an SGPR. This seems to be intentional,
and partially tested already.

The documentation seems to describe addr64 in terms of which registers
addressing modifiers come from, but I would expect to always need
addr64 when using 64-bit pointers. If no offset is applied,
it makes sense to not need to worry about doing a 64-bit add
for the final address. A small immediate offset can be applied,
so is it OK to not have addr64 set if a carry is necessary when adding
the base pointer in the resource to the offset?

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217785 91177308-0d34-0410-b5e6-96231b3b80d8
Add unit test for r217454


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217786 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Make sure double vector fmul is tested

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217787 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Prefer selecting more e64 instruction forms.

Add some more tests to make sure better operand
choices are still made. Leave some cases that seem
to have no reason to ever be e64 alone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217789 91177308-0d34-0410-b5e6-96231b3b80d8