Memory Dependence Analysis: fix a miscompile that uses DT to approxmiate the
reachablity.

We conservatively approximate the reachability analysis by saying it is not
reachable if there is a single path starting from "From" and the path does not
reach "To".

rdar://12801584

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171512 91177308-0d34-0410-b5e6-96231b3b80d8
After reducing the size of an operation in the DAG we zero-extend the reduced
bitwidth op back to the original size. If we reduce ANDs then this can cause
an endless loop. This patch changes the ZEXT to ANY_EXTEND if the demanded bits
are equal or smaller than the size of the reduced operation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170505 91177308-0d34-0410-b5e6-96231b3b80d8
LegalizeDAG: Allow type promotion for scalar stores

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169772 91177308-0d34-0410-b5e6-96231b3b80d8
LegalizeDAG: Allow type promotion of scalar loads

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169773 91177308-0d34-0410-b5e6-96231b3b80d8