SelectionDAG::getConstantPool will automatically determine an appropriate alignment if one is not specified. It does this by querying the type's preferred alignment. This can end up creating quite a lot of padding when the preferred alignment for vectors is 128.
In optimize-for-size mode, it makes sense to instead query the ABI type alignment which is often smaller and causes less padding.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284381 91177308-0d34-0410-b5e6-96231b3b80d8
