Simplify a vpermil* with constant mask.

With a constant mask a vpermil* is just a shufflevector. This patch implements
that simplification. This allows us to produce denser code. It should also
allow more folding down the line.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206801 91177308-0d34-0410-b5e6-96231b3b80d8
ARM64: Refactor away a few redundant helpers.

The comment claimed that the register class information wasn't available
in the assembly parser, but that's not really true. It's just annoying to
get to. Replace the helper functions with references to the auto-generated
information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206802 91177308-0d34-0410-b5e6-96231b3b80d8
Set default value of HasExtractBitsInsn to false

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206803 91177308-0d34-0410-b5e6-96231b3b80d8
Store State objects by value in TableGen's DFAPacketizerEmitter

Removes some extra manual dynamic memory allocation/management. It does
get a bit quirky having to make State's members mutable and
pointers/references to const rather than non-const, but that's a
necessary workaround to dealing with the std::set elements.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206807 91177308-0d34-0410-b5e6-96231b3b80d8
Fix builds that use an stl missing std::set::emplace

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206821 91177308-0d34-0410-b5e6-96231b3b80d8