[SubZero] Branch optimization

src/IceTargetLoweringMIPS32.cpp

 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Implements the TargetLoweringMIPS32 class, which consists almost
@@ skipping 378 matching lines @@
     return;
   Func->dump("After stack frame mapping");
 
   // Nop insertion
   if (getFlags().getShouldDoNopInsertion()) {
     Func->doNopInsertion();
   }
 }
 
 bool TargetMIPS32::doBranchOpt(Inst *Instr, const CfgNode *NextNode) {
-  (void)Instr;
-  (void)NextNode;
-  UnimplementedError(getFlags());
+  if (auto *Br = llvm::dyn_cast<InstMIPS32Br>(Instr)) {
+    return Br->optimizeBranch(NextNode);
+  }
   return false;
 }
 
 namespace {
 
 const char *RegNames[RegMIPS32::Reg_NUM] = {
 #define X(val, encode, name, scratch, preserved, stackptr, frameptr, isInt,    \
           isI64Pair, isFP32, isFP64, isVec128, alias_init)                     \
   name,
     REGMIPS32_TABLE
@@ skipping 2162 matching lines @@
   Str << "\t.set\t"
       << "nomips16\n";
 }
 
 SmallBitVector TargetMIPS32::TypeToRegisterSet[RCMIPS32_NUM];
 SmallBitVector TargetMIPS32::TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
 SmallBitVector TargetMIPS32::RegisterAliases[RegMIPS32::Reg_NUM];
 
 } // end of namespace MIPS32
 } // end of namespace Ice