[FastISel] Add basic infrastructure to support a target-independent call lowering hook in FastISel. WIP

The infrastructure mimics the call lowering we have already in place for
SelectionDAG, but with limitations. For example structure return demotion and
non-simple types are not supported (yet).

Currently every backend has its own implementation and duplicated code for call
lowering. There is also no specified interface that could be called from
target-independent code. The target-hook is opt-in and doesn't affect current
implementations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212848 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel] Add target-independent patchpoint intrinsic support. WIP.

This implements the target-independent lowering for the patchpoint
intrinsic. Targets have to implement the FastLowerCall
hook to support this intrinsic.

Related to <rdar://problem/17427052>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212849 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan] Introduce a struct representing the layout of metadata entry in llvm.asan.globals.

No functionality change.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212850 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][X86] Implement the FastLowerIntrinsicCall hook.

Rename X86VisitIntrinsicCall -> FastLowerIntrinsicCall, which effectively
implements the target hook.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212851 91177308-0d34-0410-b5e6-96231b3b80d8