- Avoid using floating point stores to implement memset unless the value is zero.

- Avoid using floating point stores to implement memset unless the value is zero.
- Do not try to infer GV alignment unless its type is sized. It's not possible to infer alignment if it has opaque type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100118 91177308-0d34-0410-b5e6-96231b3b80d8