Make better use of the PHINode API.

Change various bits of code to make better use of the existing PHINode
API, to insulate them from forthcoming changes in how PHINodes store
their operands.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133434 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed