swift234

[Global Load Store Opts] fix a issue when a BB is its own predecessor.

When BB is its own predecessor, we can't do the following
state[BB] = state[first pred of BB]
state[BB].merge(state[other predecessors])
--> here we are merging in the updated state[BB]

Instead we should do
state[BB].merge(state[predecessors other than BB])


Swift SVN r20114