Fixing issues in type scavenger related to copy efficiency (#2030)

Author: jgstarIntel

lib/SPIRV/SPIRVTypeScavenger.cpp

@@ -344,7 +344,7 @@ bool SPIRVTypeScavenger::unifyType(Type *T1, Type *T2) {
         return false;
       if (!unifyType(FT1->getReturnType(), FT2->getReturnType()))
         return false;
-      for (auto [PT1, PT2] : zip(FT1->params(), FT2->params()))
+      for (const auto &[PT1, PT2] : zip(FT1->params(), FT2->params()))
         if (!unifyType(PT1, PT2))
           return false;
       return true;
@@ -414,7 +414,7 @@ void SPIRVTypeScavenger::typeModule(Module &M) {
   // If there are any type variables we couldn't resolve, fallback to assigning
   // them as an i8* type.
   Type *Int8Ty = Type::getInt8Ty(M.getContext());
-  for (auto [TypeVarNum, TypeVar] : enumerate(TypeVariables)) {
+  for (const auto &[TypeVarNum, TypeVar] : enumerate(TypeVariables)) {
     unsigned PrimaryVar = UnifiedTypeVars.join(TypeVarNum, TypeVarNum);
     Type *LeaderTy = TypeVariables[PrimaryVar];
     if (TypeVar)
@@ -605,7 +605,8 @@ bool SPIRVTypeScavenger::typeIntrinsicCall(
 void SPIRVTypeScavenger::typeFunctionParams(
     CallBase &CB, FunctionType *FT, unsigned ArgStart, bool IncludeRet,
     SmallVectorImpl<TypeRule> &TypeRules) {
-  for (auto [U, ArgTy] : zip(drop_begin(CB.args(), ArgStart), FT->params())) {
+  for (const auto &[U, ArgTy] :
+       zip(drop_begin(CB.args(), ArgStart), FT->params())) {
     if (hasPointerType(U->getType())) {
       TypeRules.push_back(TypeRule::is(U, ArgTy));
     }