Transforms: use typedef rather than using aliases

Visual Studio 2012 apparently does not support using alias declarations.  Use
the more traditional typedef approach.  This should let the Windows buildbots
pass.  NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221554 91177308-0d34-0410-b5e6-96231b3b80d8
[Reassociate] Better preserve NSW/NUW flags.
Part of PR12985.

Phabricator Revision: http://reviews.llvm.org/D6172

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221555 91177308-0d34-0410-b5e6-96231b3b80d8
SelectionDAG: Assert if we truncate SDNode's NumOperands or NumValues

No functionality change intended, this just stops us early if we created
a bad SDNode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221560 91177308-0d34-0410-b5e6-96231b3b80d8