[Subzero][MIPS] Implement conditional branches and integer comparisons

src/IceTargetLoweringMIPS32.h

 //===- subzero/src/IceTargetLoweringMIPS32.h - MIPS32 lowering ---*- C++-*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 198 matching lines @@
   }
 
   void _or(Variable *Dest, Variable *Src0, Variable *Src1) {
     Context.insert<InstMIPS32Or>(Dest, Src0, Src1);
   }
 
   void _ori(Variable *Dest, Variable *Src, uint32_t Imm) {
     Context.insert<InstMIPS32Ori>(Dest, Src, Imm);
   }
 
+  void _slt(Variable *Dest, Variable *Src0, Variable *Src1) {
+    Context.insert<InstMIPS32Slt>(Dest, Src0, Src1);
+  }
+
+  void _slti(Variable *Dest, Variable *Src, uint32_t Imm) {
+    Context.insert<InstMIPS32Slti>(Dest, Src, Imm);
+  }
+
+  void _sltiu(Variable *Dest, Variable *Src, uint32_t Imm) {
+    Context.insert<InstMIPS32Sltiu>(Dest, Src, Imm);
+  }
+
+  void _sltu(Variable *Dest, Variable *Src0, Variable *Src1) {
+    Context.insert<InstMIPS32Sltu>(Dest, Src0, Src1);
+  }
+
   void _sub(Variable *Dest, Variable *Src0, Variable *Src1) {
     Context.insert<InstMIPS32Sub>(Dest, Src0, Src1);
   }
 
-  void _sltu(Variable *Dest, Variable *Src0, Variable *Src1) {
-    Context.insert<InstMIPS32Sltu>(Dest, Src0, Src1);
-  }
-
   void _subu(Variable *Dest, Variable *Src0, Variable *Src1) {
     Context.insert<InstMIPS32Subu>(Dest, Src0, Src1);
   }
 
   void _xor(Variable *Dest, Variable *Src0, Variable *Src1) {
     Context.insert<InstMIPS32Xor>(Dest, Src0, Src1);
   }
 
+  void _xori(Variable *Dest, Variable *Src, uint32_t Imm) {
+    Context.insert<InstMIPS32Xori>(Dest, Src, Imm);
+  }
+
   void lowerArguments() override;
 
   /// Operand legalization helpers.  To deal with address mode constraints,
   /// the helpers will create a new Operand and emit instructions that
   /// guarantee that the Operand kind is one of those indicated by the
   /// LegalMask (a bitmask of allowed kinds).  If the input Operand is known
   /// to already meet the constraints, it may be simply returned as the result,
   /// without creating any new instructions or operands.
   enum OperandLegalization {
     Legal_None = 0,
     Legal_Reg = 1 << 0, // physical register, not stack location
     Legal_Imm = 1 << 1,
     Legal_Mem = 1 << 2,
     Legal_Default = ~Legal_None
   };
   typedef uint32_t LegalMask;
   Operand *legalize(Operand *From, LegalMask Allowed = Legal_Default,
                     RegNumT RegNum = RegNumT());
 
   Variable *legalizeToVar(Operand *From, RegNumT RegNum = RegNumT());
 
   Variable *legalizeToReg(Operand *From, RegNumT RegNum = RegNumT());
 
   Variable *makeReg(Type Ty, RegNumT RegNum = RegNumT());
 
+  Variable *getZero() {
+    return getPhysicalRegister(RegMIPS32::Reg_ZERO, IceType_i32);
+  }
+
   Variable *I32Reg(RegNumT RegNum = RegNumT()) {
     return makeReg(IceType_i32, RegNum);
   }
 
   static Type stackSlotType();
   Variable *copyToReg(Operand *Src, RegNumT RegNum = RegNumT());
 
   void addProlog(CfgNode *Node) override;
   void addEpilog(CfgNode *Node) override;
 
@@ skipping 16 matching lines @@
   void lowerInt64Arithmetic(const InstArithmetic *Instr, Variable *Dest,
                             Operand *Src0, Operand *Src1);
   void lowerAssign(const InstAssign *Instr) override;
   void lowerBr(const InstBr *Instr) override;
   void lowerBreakpoint(const InstBreakpoint *Instr) override;
   void lowerCall(const InstCall *Instr) override;
   void lowerCast(const InstCast *Instr) override;
   void lowerExtractElement(const InstExtractElement *Instr) override;
   void lowerFcmp(const InstFcmp *Instr) override;
   void lowerIcmp(const InstIcmp *Instr) override;
+  void lower64Icmp(const InstIcmp *Instr);
   void lowerIntrinsicCall(const InstIntrinsicCall *Instr) override;
   void lowerInsertElement(const InstInsertElement *Instr) override;
   void lowerLoad(const InstLoad *Instr) override;
   void lowerPhi(const InstPhi *Instr) override;
   void lowerRet(const InstRet *Instr) override;
   void lowerSelect(const InstSelect *Instr) override;
   void lowerStore(const InstStore *Instr) override;
   void lowerSwitch(const InstSwitch *Instr) override;
   void lowerUnreachable(const InstUnreachable *Instr) override;
   void prelowerPhis() override;
@@ skipping 62 matching lines @@
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H