[AArch64][GlobalISel] NFC: Use CmpInst::isUnsigned instead of static helper

[paquette]

Summary

Reducing some code duplication.

We had a helper for checking if a predicate is unsigned. Remove that and use the existing function in Instructions.cpp.

llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp

static unsigned selectSelectOpc(MachineInstr &I, MachineRegisterInfo &MRI,
   LLT Ty = MRI.getType(I.getOperand(0).getReg());
   if (Ty == LLT::scalar(32))
     return IsFP ? AArch64::FCSELSrrr : AArch64::CSELWr;
   else if (Ty == LLT::scalar(64) || Ty == LLT::pointer(0, 64))
     return IsFP ? AArch64::FCSELDrrr : AArch64::CSELXr;
   return 0;
 }
 
-/// Returns true if \p P is an unsigned integer comparison predicate.
-static bool isUnsignedICMPPred(const CmpInst::Predicate P) {
-  switch (P) {
-  default:
-    return false;
-  case CmpInst::ICMP_UGT:
-  case CmpInst::ICMP_UGE:
-  case CmpInst::ICMP_ULT:
-  case CmpInst::ICMP_ULE:
-    return true;
-  }
-}
-
 static AArch64CC::CondCode changeICMPPredToAArch64CC(CmpInst::Predicate P) {
   switch (P) {
   default:
     llvm_unreachable("Unknown condition code!");
   case CmpInst::ICMP_NE:
     return AArch64CC::NE;
   case CmpInst::ICMP_EQ:
     return AArch64CC::EQ;
MachineInstr *AArch64InstructionSelector::tryFoldIntegerCompare(
   // Given this:
   //
   // z = G_AND x, y
   // G_ICMP z, 0
   //
   // Produce this if the compare is signed:
   //
   // tst x, y
-  if (!isUnsignedICMPPred(P) && LHSDef &&
+  if (!CmpInst::isUnsigned(P) && LHSDef &&
       LHSDef->getOpcode() == TargetOpcode::G_AND) {
     // Make sure that the RHS is 0.
     auto ValAndVReg = getConstantVRegValWithLookThrough(RHS.getReg(), MRI);
     if (!ValAndVReg || ValAndVReg->Value != 0)
       return nullptr;
 
     return emitTST(LHSDef->getOperand(1),
                    LHSDef->getOperand(2), MIRBuilder);