[CodeGen] Use Register in SwitchLoweringUtils. NFC (#109092)

Use an empty Register() instead of -1U.

llvm/include/llvm/CodeGen/SwitchLoweringUtils.h

@@ -170,7 +170,7 @@ struct CaseBlock {
 struct JumpTable {
   /// The virtual register containing the index of the jump table entry
   /// to jump to.
-  unsigned Reg;
+  Register Reg;
   /// The JumpTableIndex for this jump table in the function.
   unsigned JTI;
   /// The MBB into which to emit the code for the indirect jump.
@@ -182,7 +182,7 @@ struct JumpTable {
   /// The debug location of the instruction this JumpTable was produced from.
   std::optional<SDLoc> SL; // For SelectionDAG
 
-  JumpTable(unsigned R, unsigned J, MachineBasicBlock *M, MachineBasicBlock *D,
+  JumpTable(Register R, unsigned J, MachineBasicBlock *M, MachineBasicBlock *D,
             std::optional<SDLoc> SL)
       : Reg(R), JTI(J), MBB(M), Default(D), SL(SL) {}
 };
@@ -218,7 +218,7 @@ struct BitTestBlock {
   APInt First;
   APInt Range;
   const Value *SValue;
-  unsigned Reg;
+  Register Reg;
   MVT RegVT;
   bool Emitted;
   bool ContiguousRange;
@@ -229,7 +229,7 @@ struct BitTestBlock {
   BranchProbability DefaultProb;
   bool FallthroughUnreachable = false;
 
-  BitTestBlock(APInt F, APInt R, const Value *SV, unsigned Rg, MVT RgVT, bool E,
+  BitTestBlock(APInt F, APInt R, const Value *SV, Register Rg, MVT RgVT, bool E,
                bool CR, MachineBasicBlock *P, MachineBasicBlock *D,
                BitTestInfo C, BranchProbability Pr)
       : First(std::move(F)), Range(std::move(R)), SValue(SV), Reg(Rg),

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -838,7 +838,7 @@ void IRTranslator::splitWorkItem(SwitchCG::SwitchWorkList &WorkList,
 void IRTranslator::emitJumpTable(SwitchCG::JumpTable &JT,
                                  MachineBasicBlock *MBB) {
   // Emit the code for the jump table
-  assert(JT.Reg != -1U && "Should lower JT Header first!");
+  assert(JT.Reg && "Should lower JT Header first!");
   MachineIRBuilder MIB(*MBB->getParent());
   MIB.setMBB(*MBB);
   MIB.setDebugLoc(CurBuilder->getDebugLoc());

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -2981,7 +2981,7 @@ void SelectionDAGBuilder::visitSwitchCase(CaseBlock &CB,
 void SelectionDAGBuilder::visitJumpTable(SwitchCG::JumpTable &JT) {
   // Emit the code for the jump table
   assert(JT.SL && "Should set SDLoc for SelectionDAG!");
-  assert(JT.Reg != -1U && "Should lower JT Header first!");
+  assert(JT.Reg && "Should lower JT Header first!");
   EVT PTy = DAG.getTargetLoweringInfo().getJumpTableRegTy(DAG.getDataLayout());
   SDValue Index = DAG.getCopyFromReg(getControlRoot(), *JT.SL, JT.Reg, PTy);
   SDValue Table = DAG.getJumpTable(JT.JTI, PTy);
@@ -3261,10 +3261,9 @@ void SelectionDAGBuilder::visitBitTestHeader(BitTestBlock &B,
 
 /// visitBitTestCase - this function produces one "bit test"
 void SelectionDAGBuilder::visitBitTestCase(BitTestBlock &BB,
-                                           MachineBasicBlock* NextMBB,
+                                           MachineBasicBlock *NextMBB,
                                            BranchProbability BranchProbToNext,
-                                           unsigned Reg,
-                                           BitTestCase &B,
+                                           Register Reg, BitTestCase &B,
                                            MachineBasicBlock *SwitchBB) {
   SDLoc dl = getCurSDLoc();
   MVT VT = BB.RegVT;

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h

@@ -526,7 +526,7 @@ public:
   void visitBitTestHeader(SwitchCG::BitTestBlock &B,
                           MachineBasicBlock *SwitchBB);
   void visitBitTestCase(SwitchCG::BitTestBlock &BB, MachineBasicBlock *NextMBB,
-                        BranchProbability BranchProbToNext, unsigned Reg,
+                        BranchProbability BranchProbToNext, Register Reg,
                         SwitchCG::BitTestCase &B, MachineBasicBlock *SwitchBB);
   void visitJumpTable(SwitchCG::JumpTable &JT);
   void visitJumpTableHeader(SwitchCG::JumpTable &JT,

llvm/lib/CodeGen/SwitchLoweringUtils.cpp

@@ -254,7 +254,7 @@ bool SwitchCG::SwitchLowering::buildJumpTable(const CaseClusterVector &Clusters,
                      ->createJumpTableIndex(Table);
 
   // Set up the jump table info.
-  JumpTable JT(-1U, JTI, JumpTableMBB, nullptr, SL);
+  JumpTable JT(Register(), JTI, JumpTableMBB, nullptr, SL);
   JumpTableHeader JTH(Clusters[First].Low->getValue(),
                       Clusters[Last].High->getValue(), SI->getCondition(),
                       nullptr, false);
@@ -455,7 +455,7 @@ bool SwitchCG::SwitchLowering::buildBitTests(CaseClusterVector &Clusters,
     BTI.push_back(BitTestCase(CB.Mask, BitTestBB, CB.BB, CB.ExtraProb));
   }
   BitTestCases.emplace_back(std::move(LowBound), std::move(CmpRange),
-                            SI->getCondition(), -1U, MVT::Other, false,
+                            SI->getCondition(), Register(), MVT::Other, false,
                             ContiguousRange, nullptr, nullptr, std::move(BTI),
                             TotalProb);