Add the PPC64 popcntd instruction

PPC ISA 2.06 (P7, A2, etc.) has a popcntd instruction. Add this instruction and
tell TTI about it so that popcount-loop recognition will know about it.

llvm-svn: 178233
diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
index 5e9ad34..00037ed 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -122,9 +122,8 @@
 
 PPCTTI::PopcntSupportKind PPCTTI::getPopcntSupport(unsigned TyWidth) const {
   assert(isPowerOf2_32(TyWidth) && "Ty width must be power of 2");
-  // FIXME: PPC currently does not have custom popcnt lowering even though
-  // there is hardware support. Once this is fixed, update this function
-  // to reflect the real capabilities of the hardware.
+  if (ST->hasPOPCNTD() && TyWidth <= 64)
+    return PSK_FastHardware;
   return PSK_Software;
 }