Add fp128 rtlib function names to LLVM

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171867 91177308-0d34-0410-b5e6-96231b3b80d8
Rename the enum members to match the LLVM coding style.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171868 91177308-0d34-0410-b5e6-96231b3b80d8
Code cleanup: refactor the switch statements in the generation of reduction variables into an IR builder call.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171871 91177308-0d34-0410-b5e6-96231b3b80d8
Rename statistic for instruction fragments -> relaxable



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171872 91177308-0d34-0410-b5e6-96231b3b80d8
Docs: mention that we support float reductions when -ffast-math is used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171873 91177308-0d34-0410-b5e6-96231b3b80d8