Add the PPC64 ldbrx/stdbrx instructions

These are 64-bit load/store with byte-swap, and available on the P7 and the A2.
Like the similar instructions for 16- and 32-bit words, these are matched in the
target DAG-combine phase against load/store-bswap pairs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178276 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCSubtarget.h b/lib/Target/PowerPC/PPCSubtarget.h
index 070a9a9..36436f6 100644
--- a/lib/Target/PowerPC/PPCSubtarget.h
+++ b/lib/Target/PowerPC/PPCSubtarget.h
@@ -80,6 +80,7 @@
   bool HasSTFIWX;
   bool HasISEL;
   bool HasPOPCNTD;
+  bool HasLDBRX;
   bool IsBookE;
   bool HasLazyResolverStubs;
   bool IsJITCodeModel;
@@ -161,6 +162,7 @@
   bool hasMFOCRF() const { return HasMFOCRF; }
   bool hasISEL() const { return HasISEL; }
   bool hasPOPCNTD() const { return HasPOPCNTD; }
+  bool hasLDBRX() const { return HasLDBRX; }
   bool isBookE() const { return IsBookE; }
 
   const Triple &getTargetTriple() const { return TargetTriple; }