Fix a logic bug when copying fast-math flags.

"Setting" does not equal "copying". This bug has sat dormant for 2 reasons:
1. The unit test was not adequate.
2. Every current user of the "copyFastMathFlags" API is operating on a new instruction.
   (ie, all existing fast-math flags are off). If you copy flags to an existing
   instruction that has some flags on already, you will not necessarily turn them off
   as expected.

I uncovered this bug while trying to implement a fix for PR20802.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216939 91177308-0d34-0410-b5e6-96231b3b80d8
Fix MemoryDependenceAnalysis in cases where QueryInstr is a CmpXchg or a AtomicRMW

Summary:
MemoryDependenceAnalysis is currently cautious when the QueryInstr is an atomic
load or store, but I forgot to check for atomic cmpxchg/atomicrmw. This patch
is a way of fixing that, and making it less brittle (i.e. no risk that I forget
another possible kind of atomic, even if the IR ends up changing in the future),
by adding a fallback checking mayReadOrWriteFromMemory.

Thanks to Philip Reames for finding this bug and suggesting this solution in
http://reviews.llvm.org/D4845

Sadly, I don't see how to add a test for this, since the passes depending on
MemoryDependenceAnalysis won't trigger for an atomic rmw anyway. Does anyone
see a way for testing it?

Test Plan: none possible at first sight

Reviewers: jfb, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5019

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216940 91177308-0d34-0410-b5e6-96231b3b80d8
cmake: Don't reject unknown cpp files that start with .

Some editors create hidden file backups in the same
directory as the file, and it's annoying when cmake
errors on them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216941 91177308-0d34-0410-b5e6-96231b3b80d8
Refactor LowerFABS and LowerFNEG into one function (x86) (NFC)

We duplicate ~30 lines of code to lower FABS and FNEG for x86, so this patch combines them into one function. 
No functional change intended, so no additional test cases. Test-suite behavior is unchanged.

Differential Revision: http://reviews.llvm.org/D5064



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216942 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Fix hardcoded register numbers in test

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216944 91177308-0d34-0410-b5e6-96231b3b80d8