[LCG] Rather than doing a linear time SmallSetVector removal of each
child from the worklist, wait until we actually need to pop another
element off of the worklist and skip over any that were already visited
by the DFS. This also enables swapping the nodes of the SCC into the
worklist. No functionality changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207212 91177308-0d34-0410-b5e6-96231b3b80d8
[LCG] During the incremental re-build of an SCC after removing an edge,
remove the nodes in the SCC from the SCC map entirely prior to the DFS
walk. This allows the SCC map to represent both the state of
not-yet-re-added-to-an-SCC and added-back-to-this-SCC independently. The
first is being missing from the SCC map, the second is mapping back to
'this'. In a subsequent commit, I'm going to use this property to
simplify the new node list for this SCC.

In theory, I think this also makes the contract for orphaning a node
from the graph slightly less confusing. Now it is also orphaned from the
SCC graph. Still, this isn't quite right either, and so I'm not adding
test cases here. I'll add test cases for the behavior of orphaning nodes
when the code *actually* supports it. The change here is mostly
incidental, my goal is simplifying the algorithm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207213 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM64] Support crc predicate on ARM64.

According to the specification, CRC is an optional extension of the
architecture.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207214 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM64] Add RUN lines for "–target arm64 –mattr=-fp-armv8" on AArch64 no-fp test.

This patch is a supplement of implementing predicate of FP, enabling aarch64 backend
no-fp tests on arm64 target for verification. During this, one bug is exposed and
fixed by this patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207215 91177308-0d34-0410-b5e6-96231b3b80d8
[LCG] During the incremental update of an SCC, switch to using the
SCCMap to test for nodes that have been re-added to the root SCC rather
than a set vector. We already have done the SCCMap lookup, we juts need
to test it in two different ways. In turn, do most of the processing of
these nodes as they go into the root SCC rather than lazily. This
simplifies the final loop to just stitch the root SCC into its
children's parent sets. No functionlatiy changed.

However, this makes a few things painfully obvious, which was my intent.
=] There is tons of repeated code introduced here and elsewhere. I'm
splitting the refactoring of that code into helpers from this change so
its clear that this is the change which switches the datastructures used
around, and the other is a pure factoring & deduplication of code
change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207217 91177308-0d34-0410-b5e6-96231b3b80d8