Re-apply the memory operand changes, with a fix for the static

Re-apply the memory operand changes, with a fix for the static
initializer problem, a minor tweak to the way the
DAGISelEmitter finds load/store nodes, and a renaming of the
new PseudoSourceValue objects.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46827 91177308-0d34-0410-b5e6-96231b3b80d8