Give SplitBlockAndInsertIfThen the ability to update a domtree.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213045 91177308-0d34-0410-b5e6-96231b3b80d8
[dfsan] Move combineShadows to DFSanFunction in preparation for it to use a domtree.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213046 91177308-0d34-0410-b5e6-96231b3b80d8
[dfsan] Introduce an optimization to reduce the number of union queries.

Specifically, when building a union query, if we are dominated by an identical
query then use the result of that query instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213047 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "[FastISel][X86] Remove no longer needed functions."
Revert "[FastISel][X86] Implement the FastLowerIntrinsicCall hook."
Revert "[FastISel][X86] Implement the FastLowerCall hook."

This reverts commit r213035, r213036, and r213037 to make the
buildbots happy again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213048 91177308-0d34-0410-b5e6-96231b3b80d8