[X86] Use min/max to optimze unsigend vector comparison on X86

Use PMIN/PMAX for UGE/ULE vector comparions to reduce the number of required
instructions. This trick also works for UGT/ULT, but there is no advantage in
doing so. It wouldn't reduce the number of instructions and it would actually
reduce performance.

Reviewer: Ben

radar:5972691



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186432 91177308-0d34-0410-b5e6-96231b3b80d8
Reapply r185393.

Original commit message:

Remove floating point computations from SpillPlacement.cpp.

Patch by Benjamin Kramer!

Use the BlockFrequency class instead of floats in the Hopfield network
computations. This rescales the node Bias field from a [-2;2] float
range to two block frequencies BiasN and BiasP pulling in opposite
directions. This construct has a more predictable behavior when block
frequencies saturate.

The per-node scaling factors are no longer necessary, assuming the block
frequencies around a bundle are consistent.

This patch can cause the register allocator to make different spilling
decisions. The differences should be small.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186434 91177308-0d34-0410-b5e6-96231b3b80d8
Remove floats from live range splitting costs.

These floats all represented block frequencies anyway, so just use the
BlockFrequency class directly.

Some floating point computations remain in tryLocalSplit(). They are
estimating spill weights which are still floats.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186435 91177308-0d34-0410-b5e6-96231b3b80d8
Cleanup testing case by using a shorter name for types.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186436 91177308-0d34-0410-b5e6-96231b3b80d8
Fix test not to fail when the target doesn't use leading underscores on symbols.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186439 91177308-0d34-0410-b5e6-96231b3b80d8
Label names also differ between platforms. Use a relaxed regex.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186442 91177308-0d34-0410-b5e6-96231b3b80d8