[FuzzMutate] InstModStrategy: switch nsw/nuw/inbount instead of repeated setting it

llvm/lib/FuzzMutate/IRMutator.cpp

void InstModificationIRStrategy::mutate(Instruction &Inst,
   switch (Inst.getOpcode()) {
   default:
     break;
   // Add nsw, nuw flag
   case Instruction::Add:
   case Instruction::Mul:
   case Instruction::Sub:
   case Instruction::Shl:
-    Modifications.push_back([&Inst]() { Inst.setHasNoSignedWrap(true); });
-    Modifications.push_back([&Inst]() { Inst.setHasNoSignedWrap(false); });
-    Modifications.push_back([&Inst]() { Inst.setHasNoUnsignedWrap(true); });
-    Modifications.push_back([&Inst]() { Inst.setHasNoUnsignedWrap(false); });
+    Modifications.push_back(
+        [&Inst]() { Inst.setHasNoSignedWrap(!Inst.hasNoSignedWrap()); });
+    Modifications.push_back(
+        [&Inst]() { Inst.setHasNoUnsignedWrap(!Inst.hasNoUnsignedWrap()); });
     break;
   case Instruction::ICmp:
     CI = cast<ICmpInst>(&Inst);
     for (unsigned p = CmpInst::FIRST_ICMP_PREDICATE;
          p <= CmpInst::LAST_ICMP_PREDICATE; p++) {
       Modifications.push_back(
           [CI, p]() { CI->setPredicate(static_cast<CmpInst::Predicate>(p)); });
     }
     break;
   // Add inbound flag.
   case Instruction::GetElementPtr:
     GEP = cast<GetElementPtrInst>(&Inst);
-    Modifications.push_back([GEP]() { GEP->setIsInBounds(true); });
-    Modifications.push_back([GEP]() { GEP->setIsInBounds(false); });
+    Modifications.push_back(
+        [GEP]() { GEP->setIsInBounds(!GEP->isInBounds()); });
     break;
   // Add exact flag.
   case Instruction::UDiv:
   case Instruction::SDiv:
   case Instruction::LShr:
   case Instruction::AShr:
     Modifications.push_back([&Inst] { Inst.setIsExact(!Inst.isExact()); });
     break;