ARM64: add acquire/release versions of the existing atomic intrinsics.

These will be needed to support IR-level lowering of atomic
operations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206489 91177308-0d34-0410-b5e6-96231b3b80d8
ARM64: switch to IR-based atomic operations.

Goodbye code!

(Game: spot the bug fixed by the change).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206490 91177308-0d34-0410-b5e6-96231b3b80d8
ManagedStatic is never built with a null constructor, remove support for it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206492 91177308-0d34-0410-b5e6-96231b3b80d8
ARM64: [su]xtw use W regs as inputs, not X regs.

Update the SXT[BHW]/UXTW instruction aliases and the shifted reg addressing
mode handling.

PR19455 and rdar://16650642

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206495 91177308-0d34-0410-b5e6-96231b3b80d8
Improve ARM64 vector creation

This patch improves the performance of vector creation in caseiswhere where
several of the lanes in the vector are a constant floating point value. It
also includes new patterns to fold together some of the instructions when the
value is 0.0f. Test cases included.

rdar://16349427

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206496 91177308-0d34-0410-b5e6-96231b3b80d8