Teach the foldable tables about 128-bit AVX instructions and make the

Teach the foldable tables about 128-bit AVX instructions and make the
alignment check for 256-bit classes more strict. There're no testcases
but we catch more folding cases for AVX while running single and multi
sources in the llvm testsuite.

Since some 128-bit AVX instructions have different number of operands
than their SSE counterparts, they are placed in different tables.

256-bit AVX instructions should also be added in the table soon. And
there a few more 128-bit versions to handled, which should come in
the following commits.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139687 91177308-0d34-0410-b5e6-96231b3b80d8