[PPC64] Add support for clrbhrb, mfbhrbe, rfebb.

This patch adds support for the ISA 2.07 additions involving the
branch history rolling buffer and event-based branching.  These will
not be used by typical applications, so built-in support is not
required.  They will only be available via inline assembly.

Assembly/disassembly tests are included in the patch.

llvm-svn: 238032
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 43ffef2..f8ebae1 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1048,6 +1048,9 @@
   case PPCISD::ADDI_DTPREL_L:   return "PPCISD::ADDI_DTPREL_L";
   case PPCISD::VADD_SPLAT:      return "PPCISD::VADD_SPLAT";
   case PPCISD::SC:              return "PPCISD::SC";
+  case PPCISD::CLRBHRB:         return "PPCISD::CLRBHRB";
+  case PPCISD::MFBHRBE:         return "PPCISD::MFBHRBE";
+  case PPCISD::RFEBB:           return "PPCISD::RFEBB";
   case PPCISD::XXSWAPD:         return "PPCISD::XXSWAPD";
   case PPCISD::QVFPERM:         return "PPCISD::QVFPERM";
   case PPCISD::QVGPCI:          return "PPCISD::QVGPCI";