Add a test for assignment operator behavior which was changed in
r195239, as well as a comment about the fact that assigning over
a moved-from object was in fact tested. Addresses some of the review
feedback on r195239.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195260 91177308-0d34-0410-b5e6-96231b3b80d8
Make the moved-from SmallPtrSet be a valid, empty, small-state object.
Enhance the tests to actually require moves in C++11 mode, in addition
to testing the moved-from state. Further enhance the tests to cover
copy-assignment into a moved-from object and moving a large-state
object. (Note that we can't really test small-state vs. large-state as
that isn't an observable property of the API really.) This should finish
addressing review on r195239.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195261 91177308-0d34-0410-b5e6-96231b3b80d8
CR feedback for r195166: Add comments regarding type unit mapping and type units disabling cross-CU sharing.

Changes suggested by Manman Ren.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195262 91177308-0d34-0410-b5e6-96231b3b80d8
DwarfCompileUnit: Initialize DebugInfoOffset.

While not strictly necessary (the class has an invariant that
"setDebugInfoOffset" is called before "getDebugInfoOffset" - anyone
client that actually gets the default zero offset is buggy/broken) this
is consistent with the code as originally written and the removal of the
initialization was an accident in r195166.

Suggested by Manman Ren.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195263 91177308-0d34-0410-b5e6-96231b3b80d8
MachineBlockPlacement: Strengthen the source order bias when picking an exit block.

We now only allow breaking source order if the exit block frequency is
significantly higher than the other exit block. The actual bias is
currently under a flag so the best cut-off can be found; the flag
defaults to the old behavior. The idea is to get some benchmark coverage
over different values for the flag and pick the best one.

When we require the new frequency to be at least 20% higher than the old
frequency I see a 5% speedup on zlib's deflate when compressing a random
file on x86_64/westmere. Hal reported a small speedup on Fhourstones on
a BG/Q and no regressions in the test suite.

The test case is the full long_match function from zlib's deflate. I was
reluctant to add it for previous tweaks to branch probabilities because
it's large and potentially fragile, but changed my mind since it's an
important use case and more likely to break with all the current work
going into the PGO infrastructure.

Differential Revision: http://llvm-reviews.chandlerc.com/D2202

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195265 91177308-0d34-0410-b5e6-96231b3b80d8