Remove PPC avoidWriteAfterWrite callback

As a follow-up to r158719, remove PPCRegisterInfo::avoidWriteAfterWrite.
Jakob pointed out in response to r158719 that this callback is currently unused
and so this has no effect (and the speedups that I thought that I had observed
as a result of implementing this function must have been noise).

llvm-svn: 177228

llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp

@@ -163,20 +163,6 @@ PPCRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
   }
 }
 
-bool
-PPCRegisterInfo::avoidWriteAfterWrite(const TargetRegisterClass *RC) const {
-  switch (RC->getID()) {
-  case PPC::G8RCRegClassID:
-  case PPC::GPRCRegClassID:
-  case PPC::F8RCRegClassID:
-  case PPC::F4RCRegClassID:
-  case PPC::VRRCRegClassID:
-    return true;
-  default:
-    return false;
-  }
-}
-
 //===----------------------------------------------------------------------===//
 // Stack Frame Processing methods
 //===----------------------------------------------------------------------===//

llvm/lib/Target/PowerPC/PPCRegisterInfo.h

@@ -47,8 +47,6 @@ public:
 
   BitVector getReservedRegs(const MachineFunction &MF) const;
 
-  virtual bool avoidWriteAfterWrite(const TargetRegisterClass *RC) const;
-
   /// We require the register scavenger.
   bool requiresRegisterScavenging(const MachineFunction &MF) const {
     return true;