Subzero: Refactor x86 register representation to actively use aliases.

src/IceTargetLoweringMIPS32.h

Index: src/IceTargetLoweringMIPS32.h
diff --git a/src/IceTargetLoweringMIPS32.h b/src/IceTargetLoweringMIPS32.h
index 3cd1687ea0ed1ae1458d946a7299702f00b398f2..a63ca353e7bb3301357238115814258b7c9ab0e9 100644
--- a/src/IceTargetLoweringMIPS32.h
+++ b/src/IceTargetLoweringMIPS32.h
@@ -23,6 +23,9 @@
 
 namespace Ice {
 
+// Extend enum RegClass with MIPS32-specific register classes (if any).
+enum RegClassMIPS32 : uint8_t { RCMIPS32_NUM = RC_Target };
+
 class TargetMIPS32 : public TargetLowering {
   TargetMIPS32() = delete;
   TargetMIPS32(const TargetMIPS32 &) = delete;
@@ -42,8 +45,11 @@ public:
   IceString getRegName(SizeT RegNum, Type Ty) const override;
   llvm::SmallBitVector getRegisterSet(RegSetMask Include,
                                       RegSetMask Exclude) const override;
-  const llvm::SmallBitVector &getRegisterSetForType(Type Ty) const override {
-    return TypeToRegisterSet[Ty];
+  const llvm::SmallBitVector &
+  getRegistersForClass(const Variable *Var) const override {
+    RegClass RC = Var->getRegClass();
+    assert(RC < RC_Target);
+    return TypeToRegisterSet[RC];
   }
   const llvm::SmallBitVector &getAliasesForRegister(SizeT Reg) const override {
     return RegisterAliases[Reg];
@@ -231,7 +237,7 @@ protected:
 
   bool UsesFramePointer = false;
   bool NeedsStackAlignment = false;
-  static llvm::SmallBitVector TypeToRegisterSet[IceType_NUM];
+  static llvm::SmallBitVector TypeToRegisterSet[RCMIPS32_NUM];
   static llvm::SmallBitVector RegisterAliases[RegMIPS32::Reg_NUM];
   static llvm::SmallBitVector ScratchRegs;
   llvm::SmallBitVector RegsUsed;