Fix C4018

```
warning C4018: '<' : signed/unsigned mismatch
```

compiler/codegen/CodeGenGC.cpp

@@ -233,7 +233,7 @@ OMR::CodeGenerator::buildGCMapForInstruction(TR::Instruction *instr)
            localCursor = automaticIterator.getNext())
          {
          int32_t mapIndex = localCursor->getGCMapIndex();
-         if (mapIndex >= 0 && mapIndex < atlas->getIndexOfFirstSpillTemp())
+         if (mapIndex >= 0 && unsigned(mapIndex) < atlas->getIndexOfFirstSpillTemp())
             {
             if (liveLocals && liveLocals->get(localCursor->getLiveLocalIndex()))
                {
@@ -296,7 +296,7 @@ OMR::CodeGenerator::buildGCMapForInstruction(TR::Instruction *instr)
             continue;
             }
 
-         TR_ASSERT( s->getGCMapIndex() >= atlas->getIndexOfFirstSpillTemp(), "Code Gen: error in building stack map");
+         TR_ASSERT(unsigned(s->getGCMapIndex()) >= atlas->getIndexOfFirstSpillTemp(), "Code Gen: error in building stack map");
          map->setBit(s->getGCMapIndex());
          }
       }

compiler/codegen/CodeGenRA.cpp

@@ -370,9 +370,8 @@ OMR::CodeGenerator::prepareRegistersForAssignment()
    TR_Array<TR::Register *>&    regArray=self()->getRegisterArray();
    TR::Register               *registerCursor;
    TR_RegisterMask           km, foundKindsMask = 0;
-   int i;
 
-   for (i=0; i < regArray.size(); i++)
+   for (auto i = 0U; i < regArray.size(); i++)
       {
       registerCursor = regArray[i];
       if (registerCursor->getKind() != TR_SSR)
@@ -2790,11 +2789,11 @@ OMR::CodeGenerator::simulateNodeEvaluation(TR::Node *node, TR_RegisterPressureSt
       }
 
    if (summary->_gprPressure < summary->PRESSURE_LIMIT)
-      TR_ASSERT(state->_gprPressure <= summary->_gprPressure, "Children of %s must record max register gprPressure in summary; %d > %d", self()->getDebug()->getName(node), state->_gprPressure, summary->_gprPressure);
+      TR_ASSERT(unsigned(state->_gprPressure) <= summary->_gprPressure, "Children of %s must record max register gprPressure in summary; %d > %d", self()->getDebug()->getName(node), state->_gprPressure, summary->_gprPressure);
    if (summary->_fprPressure < summary->PRESSURE_LIMIT )
-      TR_ASSERT(state->_fprPressure <= summary->_fprPressure, "Children of %s must record max register fprPressure in summary; %d > %d", self()->getDebug()->getName(node), state->_fprPressure, summary->_fprPressure);
+      TR_ASSERT(unsigned(state->_fprPressure) <= summary->_fprPressure, "Children of %s must record max register fprPressure in summary; %d > %d", self()->getDebug()->getName(node), state->_fprPressure, summary->_fprPressure);
    if (summary->_vrfPressure <= summary->PRESSURE_LIMIT)
-      TR_ASSERT(state->_vrfPressure <= summary->_vrfPressure, "Children of %s must record max register vrfPressure in summary; %d > %d", self()->getDebug()->getName(node), state->_vrfPressure, summary->_vrfPressure);
+      TR_ASSERT(unsigned(state->_vrfPressure) <= summary->_vrfPressure, "Children of %s must record max register vrfPressure in summary; %d > %d", self()->getDebug()->getName(node), state->_vrfPressure, summary->_vrfPressure);
 
 
    // Dec children's ref counts.
@@ -3341,15 +3340,15 @@ OMR::CodeGenerator::TR_RegisterPressureSummary::accumulate(
    // increase pressure.
 
    uint32_t gprs = state->_gprPressure + gprTemps;
-   if (gprs > state->_gprLimit && state->pressureIsAtRisk())
+   if (gprs > unsigned(state->_gprLimit) && state->pressureIsAtRisk())
       spill(TR_gprSpill, cg);
 
    uint32_t fprs = state->_fprPressure + fprTemps;
-   if (fprs > state->_fprLimit && state->pressureIsAtRisk())
+   if (fprs > unsigned(state->_fprLimit) && state->pressureIsAtRisk())
       spill(TR_fprSpill, cg);
 
    uint32_t vrfs = state->_vrfPressure + vrfTemps;
-   if (vrfs > state->_vrfLimit && state->pressureIsAtRisk())
+   if (vrfs > unsigned(state->_vrfLimit) && state->pressureIsAtRisk())
       spill(TR_vrfSpill, cg);
 
    accumulate(gprs, fprs, vrfs);

compiler/codegen/OMRCodeGenerator.cpp

@@ -2093,7 +2093,7 @@ OMR::CodeGenerator::compute32BitMagicValues(
          *s = div32BitMagicValues[mid][2];
          return;
          }
-      else if (d > div32BitMagicValues[mid][0])
+      else if (unsigned(d) > div32BitMagicValues[mid][0])
          {
          first = mid+1;
          }

compiler/codegen/OMRRegisterDependency.hpp

@@ -87,7 +87,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    bool containsVirtualRegister(TR::Register *r, uint32_t numberOfRegisters)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRegister() == r)
             return true;
@@ -98,7 +98,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    TR::Register *searchForRegister(TR::RealRegister::RegNum rr, uint32_t numberOfRegisters)
       {
-      for (auto i = 0;  i < numberOfRegisters; ++i)
+      for (auto i = 0U;  i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRealRegister() == rr)
             return _dependencies[i].getRegister();
@@ -109,7 +109,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    TR::Register *searchForRegister(TR::Register* vr, uint8_t flag, uint32_t numberOfRegisters, TR::CodeGenerator *cg)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRegister() == vr && (_dependencies[i].getFlags() & flag))
             return _dependencies[i].getRegister();
@@ -120,7 +120,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    TR::Register *searchForRegister(TR::RealRegister::RegNum rr, uint8_t flag, uint32_t numberOfRegisters, TR::CodeGenerator *cg)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRealRegister() == rr && (_dependencies[i].getFlags() & flag))
             return _dependencies[i].getRegister();
@@ -131,7 +131,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    int32_t searchForRegisterPos(TR::Register* vr, uint8_t flag, uint32_t numberOfRegisters, TR::CodeGenerator *cg)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRegister() == vr && (_dependencies[i].getFlags() & flag))
             return i;
@@ -147,7 +147,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    void blockRegisters(uint32_t numberOfRegisters, TR::CodeGenerator *cg = NULL)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRegister())
             {
@@ -158,7 +158,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    void unblockRegisters(uint32_t numberOfRegisters, TR::CodeGenerator *cg = NULL)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          if (_dependencies[i].getRegister())
             {
@@ -169,7 +169,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    void stopUsingDepRegs(uint32_t numberOfRegisters, TR::Register *ret1, TR::Register *ret2, TR::CodeGenerator *cg)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          auto depReg = _dependencies[i].getRegister();
          if (depReg != ret1 && depReg != ret2)
@@ -181,7 +181,7 @@ class OMR_EXTENSIBLE RegisterDependencyGroup
 
    void stopUsingDepRegs(uint32_t numberOfRegisters, int numRetReg, TR::Register **retReg, TR::CodeGenerator *cg)
       {
-      for (auto i = 0; i < numberOfRegisters; ++i)
+      for (auto i = 0U; i < numberOfRegisters; ++i)
          {
          TR::Register *depReg = _dependencies[i].getRegister();
          bool found = false;

compiler/codegen/StorageInfo.cpp

@@ -309,7 +309,7 @@ TR_StorageInfo::mayOverlapWith(TR_StorageInfo *info)
             }
          else
             {
-            if (startOne + std::min(_length, info->_length) - 1 >= overlapStart)
+            if (startOne + std::min(_length, info->_length) - 1 >= unsigned(overlapStart))
                {
                // 1 + std::min(3,6) - 1 >= 3 --> 3 >= 3
                //        123456

compiler/compile/OMRCompilation.cpp

@@ -1349,7 +1349,7 @@ bool OMR::Compilation::incInlineDepth(TR_OpaqueMethodBlock *methodInfo, TR::Reso
    int32_t maxCallerIndex = TR_ByteCodeInfo::maxCallerIndex;
    //This restriction is due to a limited number of bits allocated to callerIndex in TR_ByteCodeInfo
    //For example, in Java TR_ByteCodeInfo::maxCallerIndex is set to 4095 (12 bits and one used for signness)
-   if (self()->getNumInlinedCallSites() >= maxCallerIndex)
+   if (self()->getNumInlinedCallSites() >= unsigned(maxCallerIndex))
       {
       traceMsg(self(), "The maximum number of inlined methods %d is reached\n", TR_ByteCodeInfo::maxCallerIndex);
       return false;
@@ -1392,7 +1392,7 @@ void OMR::Compilation::decInlineDepth(bool removeInlinedCallSitesEntry)
    {
    if (removeInlinedCallSitesEntry)
       {
-      while (self()->getCurrentInlinedSiteIndex() < _inlinedCallSites.size())
+      while (unsigned(self()->getCurrentInlinedSiteIndex()) < _inlinedCallSites.size())
          _inlinedCallSites.remove(self()->getCurrentInlinedSiteIndex());
       if (self()->getOption(TR_EnableOSR))
          {
@@ -2364,7 +2364,7 @@ OMR::Compilation::setOSRCallSiteRemat(uint32_t callSiteIndex, TR::SymbolReferenc
    // Check the pending push is valid
    uint32_t callerNumPPSlots = self()->getOSRCallSiteRematSize(callSiteIndex);
    TR_ASSERT(ppSymRef->getSymbol()->isPendingPush(), "can only perform call site remat on pending pushes");
-   TR_ASSERT(slot >= 0 && slot < callerNumPPSlots, "can only perform call site remat for the caller's pending pushes");
+   TR_ASSERT(slot >= 0 && unsigned(slot) < callerNumPPSlots, "can only perform call site remat for the caller's pending pushes");
 #endif
 
    table[slot * 2] = ppSymRef->getReferenceNumber();

compiler/compile/OMRSymbolReferenceTable.cpp

@@ -1888,7 +1888,7 @@ bool OMR::SymbolReferenceTable::isNonHelper(TR::SymbolReference *symRef, CommonN
 
 bool OMR::SymbolReferenceTable::isNonHelper(int32_t ref, CommonNonhelperSymbol s)
    {
-   if (ref >= _numHelperSymbols && ref < _numHelperSymbols + getLastCommonNonhelperSymbol() && s < getLastCommonNonhelperSymbol())
+   if (unsigned(ref) >= _numHelperSymbols && unsigned(ref) < _numHelperSymbols + getLastCommonNonhelperSymbol() && s < getLastCommonNonhelperSymbol())
       {
       return ref == getNonhelperIndex(s);
       }
@@ -1905,7 +1905,7 @@ bool OMR::SymbolReferenceTable::isNonHelper(TR::SymbolReference *symRef)
 
 bool OMR::SymbolReferenceTable::isNonHelper(int32_t ref)
    {
-   return (ref >= _numHelperSymbols && ref < _numHelperSymbols + getLastCommonNonhelperSymbol());
+   return (unsigned(ref) >= _numHelperSymbols && unsigned(ref) < _numHelperSymbols + getLastCommonNonhelperSymbol());
    }
 
 OMR::SymbolReferenceTable::CommonNonhelperSymbol OMR::SymbolReferenceTable::getNonHelperSymbol(TR::SymbolReference *symRef)

compiler/compile/OSRData.cpp

@@ -135,7 +135,7 @@ TR_OSRCompilationData::addInstruction(int32_t instructionPC, TR_ByteCodeInfo bcI
 
    while (1)
       {
-      if (bcInfo.getCallerIndex()+1 >= getOSRMethodDataArray().size())
+      if (unsigned(bcInfo.getCallerIndex()+1) >= getOSRMethodDataArray().size())
          {
          if (trace)
             traceMsg(comp, "  rejected: caller index %d +1 >= %d\n", bcInfo.getCallerIndex(), getOSRMethodDataArray().size());
@@ -245,7 +245,7 @@ TR_OSRCompilationData::compressInstruction2SharedSlotMap()
          if (curInfo.size() != nextInfo.size())
             break;
 
-         int j;
+         size_t j;
          for (j = 0; j < curInfo.size(); j++)
             if (!(curInfo[j] == nextInfo[j]))
                break;
@@ -391,7 +391,7 @@ TR_OSRCompilationData::writeInstruction2SharedSlotMap(uint8_t* buffer) const
       {
       *((int32_t*)buffer) = (*itr).instructionPC; buffer += sizeof(int32_t);
       *((int32_t*)buffer) = (*itr).scratchBufferInfos.size(); buffer += sizeof(int32_t);
-      for (int j = 0; j < (*itr).scratchBufferInfos.size(); j++)
+      for (auto j = 0U; j < (*itr).scratchBufferInfos.size(); j++)
          {
          const TR_ScratchBufferInfo info = (*itr).scratchBufferInfos[j];
          buffer += info.writeToBuffer(buffer);
@@ -569,7 +569,7 @@ void TR_OSRCompilationData::buildDefiningMap(TR::Region &region)
    DefiningMaps definingMapAtOSRCodeBlocks(numOfMethods, static_cast<DefiningMap*>(NULL), comp->trMemory()->currentStackRegion());
    DefiningMaps definingMapAtPrepareForOSRCalls(numOfMethods, static_cast<DefiningMap*>(NULL), comp->trMemory()->currentStackRegion());
 
-   for (auto i = 0; i < methodDataArray.size(); ++i)
+   for (auto i = 0U; i < methodDataArray.size(); ++i)
       {
       TR_OSRMethodData *osrMethodData = methodDataArray[i];
       if (!osrMethodData)
@@ -607,7 +607,7 @@ void TR_OSRCompilationData::buildDefiningMap(TR::Region &region)
 
    if (comp->getOption(TR_TraceOSR))
       {
-      for (auto i = 0; i < methodDataArray.size(); ++i)
+      for (auto i = 0U; i < methodDataArray.size(); ++i)
          {
          TR_OSRMethodData *osrMethodData = methodDataArray[i];
          if (!osrMethodData)
@@ -625,7 +625,7 @@ void TR_OSRCompilationData::buildDefiningMap(TR::Region &region)
 void TR_OSRCompilationData::clearDefiningMap()
    {
    const TR_Array<TR_OSRMethodData *>& methodDataArray = getOSRMethodDataArray();
-   for (auto i = 0; i < methodDataArray.size(); ++i)
+   for (auto i = 0U; i < methodDataArray.size(); ++i)
       {
       TR_OSRMethodData *osrMethodData = methodDataArray[i];
       if (osrMethodData)
@@ -935,7 +935,7 @@ TR_OSRMethodData::collectSubTreeSymRefs(TR::Node *node, TR_BitVector *subTreeSym
 
 void TR_OSRCompilationData::buildSymRefOrderMap()
    {
-   for (int i = 0; i < getOSRMethodDataArray().size(); i++)
+   for (auto i = 0U; i < getOSRMethodDataArray().size(); i++)
       {
       TR_OSRMethodData* osrMethodData = getOSRMethodDataArray()[i];
       if (osrMethodData == NULL ||
@@ -953,7 +953,7 @@ void TR_OSRCompilationData::buildSymRefOrderMapAux( TR_Array<List<TR::SymbolRefe
    if (symListArray == NULL)
       return;
 
-   for (auto j = 0; j < symListArray->size(); j++)
+   for (auto j = 0U; j < symListArray->size(); j++)
       {
       List<TR::SymbolReference>& symList = (*symListArray)[j];
       bool sharedSlot = symList.getSize() > 1;
@@ -981,7 +981,7 @@ TR::Compilation& operator<< (TR::Compilation& out, const TR_OSRCompilationData&
    {
    out << "{";
    bool first = true;
-   for (int i = 0; i < osrCompilationData.getOSRMethodDataArray().size(); i++)
+   for (auto i = 0U; i < osrCompilationData.getOSRMethodDataArray().size(); i++)
       {
       TR_OSRMethodData* osrMethodData = osrCompilationData.getOSRMethodDataArray()[i];
       if (osrMethodData == NULL || osrMethodData->getOSRCodeBlock() == NULL || osrMethodData->isEmpty()) continue;
@@ -1008,7 +1008,7 @@ TR::Compilation& operator<< (TR::Compilation& out, const TR_OSRCompilationData&
          sprintf(tmp, "%x", (*itr).instructionPC);
          const  TR_OSRCompilationData::TR_ScratchBufferInfos& array2 = (*itr).scratchBufferInfos;
          out << tmp << " -> " << array2.size() << "[ ";
-         for (int j = 0; j < array2.size(); j++)
+         for (auto j = 0U; j < array2.size(); j++)
             {
             if (j != 0)
                out << ", ";
@@ -1113,7 +1113,7 @@ bool
 TR_OSRMethodData::inlinesAnyMethod() const
    {
    TR::Compilation* comp = getMethodSymbol()->comp();
-   for (int32_t i = 0; i < comp->getNumInlinedCallSites(); i++)
+   for (auto i = 0U; i < comp->getNumInlinedCallSites(); i++)
       {
       TR_InlinedCallSite& ics = comp->getInlinedCallSite(i);
       if (ics._byteCodeInfo.getCallerIndex() == inlinedSiteIndex)
@@ -1312,7 +1312,7 @@ TR_OSRMethodData::addInstruction(int32_t instructionPC, int32_t byteCodeIndex)
          bcInfoHashTab.DataAt(hashIndex)->getSlotInfos();
       TR_OSRCompilationData::TR_ScratchBufferInfos info(comp()->trMemory());
       //The "composition" of the three types of tuples happens here
-      for (int i = 0; i < slotInfos.size(); i++)
+      for (auto i = 0U; i < slotInfos.size(); i++)
          {
          int32_t scratchBufferOffset;
          bool found = slot2ScratchBufferOffset.Locate(slotInfos[i].slot, hashIndex);
@@ -1453,7 +1453,7 @@ TR_OSRSlotSharingInfo::addSlotInfo(int32_t slot, int32_t symRefNum, int32_t symR
    static bool trace = comp->getOption(TR_TraceOSR);
    TR::SymbolReferenceTable* symRefTab = comp->getSymRefTab();
    bool found = false;
-   for (int i = 0; i < slotInfos.size(); i++)
+   for (auto i = 0U; i < slotInfos.size(); i++)
       {
       TR_SlotInfo& info = slotInfos[i];
       if (info.symRefNum != -1)
@@ -1507,7 +1507,7 @@ TR_OSRSlotSharingInfo::addSlotInfo(int32_t slot, int32_t symRefNum, int32_t symR
 TR::Compilation& operator<< (TR::Compilation& out, const TR_OSRSlotSharingInfo* osrSlotSharingInfo)
    {
    out << "{slotInfos: [";
-   for (int i = 0; i < osrSlotSharingInfo->slotInfos.size(); i++)
+   for (auto i = 0U; i < osrSlotSharingInfo->slotInfos.size(); i++)
       {
       const TR_OSRSlotSharingInfo::TR_SlotInfo& info = osrSlotSharingInfo->slotInfos[i];
       if (i != 0)

compiler/compile/ResolvedMethod.cpp

@@ -551,12 +551,12 @@ void TR_ResolvedMethod::makeParameterList(TR::ResolvedMethodSymbol *methodSym)
    int32_t ordinal = 0;
 
    uint32_t parmSlots = numberOfParameterSlots();
-   for (int32_t parmIndex = 0; parmIndex < parmSlots; ++parmIndex)
+   for (auto parmIndex = 0U; parmIndex < parmSlots; ++parmIndex)
       {
       parmSymbol = methodSym->comp()->getSymRefTab()->createParameterSymbol(methodSym, slot, parmType(parmIndex));
       parmSymbol->setOrdinal(ordinal++);
 
-      char *s = getParameterTypeSignature(parmIndex);
+      char *s = getParameterTypeSignature(static_cast<int32_t>(parmIndex));
       uint32_t len = static_cast<uint32_t>(strlen(s));
       parmSymbol->setTypeSignature(s, len);