Use DomTree in MachineSink to sink over diamonds.

According to a previous FIXME comment we now not only look at MBB
successors, but also handle code sinking past them:

  x = computation
  if () {} else {}
  use x

The instruction could be sunk over the whole diamond for the
if/then/else (or loop, etc), allowing it to be sunk into other blocks
after that.

Modified test added in r204522, due to one spill less present.

Minor fixes in comments.

Patch provided by Jonas Paulsson. Reviewed by Hal Finkel.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223350 91177308-0d34-0410-b5e6-96231b3b80d8
test-release.sh: Correct the logged configure command to match the one actually issued.

--disable-timestamps was added to the configure command way back in r142647 but
the command that echos this command to the log was not updated at the time.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223351 91177308-0d34-0410-b5e6-96231b3b80d8
[X86] Simplify code. NFC.

Replaced some logic that checked if a build_vector node is doing a splat of a
non-undef value with a call to method BuildVectorSDNode::getSplatValue().
No functional change intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223354 91177308-0d34-0410-b5e6-96231b3b80d8