Revert "Revert r222040 because of bot failure."

This reverts commit r222203, reverting r222040 didn't end up turning the
bot green.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222261 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding A2_sub instruction
Renaming test files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222263 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Fix another infinite loop caused by visitFPTrunc

We would attempt to replace an frem's operand with the same operand.
This would cause InstCombine to think real work was done, causing
InstCombine to enter an infinite loop.

This fixes the second part of PR21576.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222265 91177308-0d34-0410-b5e6-96231b3b80d8
Fix an inaccurate comment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222267 91177308-0d34-0410-b5e6-96231b3b80d8