Use MCRegister in MCRegisterInfo's interfaces

[dsanders]

Summary

As part of this, define DenseMapInfo for MCRegister (and Register while I'm at it)

Depends on D65599

[dsanders]

Previous patch was based off an earlier attempt at this. Correct it to be based on D65599

[arsenm]

llvm/include/llvm/MC/MCRegister.h

72

Why *37?

llvm/lib/Target/Hexagon/BitTracker.cpp

343–344

Result should be Register?

[dsanders]

llvm/include/llvm/MC/MCRegister.h

72

No idea. It's copied directly from the DenseMapInfo<unsigned> implementation

llvm/lib/Target/Hexagon/BitTracker.cpp

343–344

Sure, I can make that change too. The reason I had to modify this line is because the ? operator couldn't decide whether to cast the third operand from Register to unsigned, or the second from unsigned to Register as both conversions exist

[arsenm]

llvm/include/llvm/MC/MCRegister.h

72

Is it possible to implement this by calling the unsigned version?

[dsanders]

• Implement DenseMapInfo<MCRegister> via DenseMapInfo<unsigned> (and likewise for Register)
• Nit in Hexagon/BitTracker.cpp

[arsenm]

LGTM

llvm/include/llvm/CodeGen/Register.h

public:
 
   bool isValid() const {
     return Reg != 0;
   }
 };
 
 // Provide DenseMapInfo for Register
 template<> struct DenseMapInfo<Register> {
-  static inline unsigned getEmptyKey() { return ~0U; }
-  static inline unsigned getTombstoneKey() { return ~0U - 1; }
-  static unsigned getHashValue(const unsigned& Val) { return Val * 37U; }
-
-  static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
-    return LHS == RHS;
+  static inline unsigned getEmptyKey() {
+    return DenseMapInfo<unsigned>::getEmptyKey();
+  }
+  static inline unsigned getTombstoneKey() {
+    return DenseMapInfo<unsigned>::getTombstoneKey();
+  }
+  static unsigned getHashValue(const unsigned &Val) {
+    return DenseMapInfo<unsigned>::getHashValue(Val);
+  }
+  static bool isEqual(const unsigned &LHS, const unsigned &RHS) {
+    return DenseMapInfo<unsigned>::isEqual(LHS, RHS);
   }
 };
 
 }
 
 #endif // ifndef LLVM_CODEGEN_REGISTER_H

llvm/include/llvm/MC/MCRegister.h

public:
 
   bool isValid() const {
     return Reg != 0;
   }
 };
 
 // Provide DenseMapInfo for MCRegister
 template<> struct DenseMapInfo<MCRegister> {
-  static inline unsigned getEmptyKey() { return ~0U; }
-  static inline unsigned getTombstoneKey() { return ~0U - 1; }
-  static unsigned getHashValue(const unsigned& Val) { return Val * 37U; }
-
-  static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
-    return LHS == RHS;
+  static inline unsigned getEmptyKey() {
+    return DenseMapInfo<unsigned>::getEmptyKey();
+  }
+  static inline unsigned getTombstoneKey() {
+    return DenseMapInfo<unsigned>::getTombstoneKey();
+  }
+  static unsigned getHashValue(const unsigned &Val) {
+    return DenseMapInfo<unsigned>::getHashValue(Val);
+  }
+  static bool isEqual(const unsigned &LHS, const unsigned &RHS) {
+    return DenseMapInfo<unsigned>::isEqual(LHS, RHS);
   }
 };
 
 }
 
 #endif // ifndef LLVM_MC_REGISTER_H

llvm/lib/Target/Hexagon/BitTracker.cpp

uint16_t BT::MachineEvaluator::getRegBitWidth(const RegisterRef &RR) const {
   // 1. find a physical register PhysR from the same class as RR.Reg,
   // 2. find a physical register PhysS that corresponds to PhysR:RR.Sub,
   // 3. find a register class that contains PhysS.
   if (Register::isVirtualRegister(RR.Reg)) {
     const auto &VC = composeWithSubRegIndex(*MRI.getRegClass(RR.Reg), RR.Sub);
     return TRI.getRegSizeInBits(VC);
   }
   assert(Register::isPhysicalRegister(RR.Reg));
-  unsigned PhysR =
+  Register PhysR =
       (RR.Sub == 0) ? Register(RR.Reg) : TRI.getSubReg(RR.Reg, RR.Sub);
   return getPhysRegBitWidth(PhysR);
 }
 
 BT::RegisterCell BT::MachineEvaluator::getCell(const RegisterRef &RR,
       const CellMapType &M) const {
   uint16_t BW = getRegBitWidth(RR);
 
   // Physical registers are assumed to be present in the map with an unknown