[x86] Teach the new vector shuffle lowering about the zero masking
abilities of INSERTPS which are really powerful and come up in very
important contexts such as forming diagonal matrices, etc.

With this I ended up being able to remove the somewhat weird helper
I added for INSERTPS because we can collapse the entire state to a no-op
mask. Added a bunch of tests for inserting into a zero-ish vector.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217117 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Add target-specific lowering for logical operations.

This change adds support for immediate and shift-left folding into logical
operations.

This fixes rdar://problem/18223183.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217118 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Cleanup and simplify 'fastSelectInstruction'. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217119 91177308-0d34-0410-b5e6-96231b3b80d8