Use const-ref in range-loop for to avoid copying pairs of std::string

No reason to create temporaries.

Differential Revision: https://reviews.llvm.org/D29871

Patch by sergio.martins!

llvm-svn: 295807

llvm/lib/IR/Attributes.cpp

@@ -1380,7 +1380,7 @@ bool AttrBuilder::overlaps(const AttrBuilder &B) const {
     return true;
 
   // Then check if any target dependent ones do.
-  for (auto I : td_attrs())
+  for (const auto &I : td_attrs())
     if (B.contains(I.first))
       return true;
 

llvm/lib/Transforms/Utils/CodeExtractor.cpp

@@ -364,7 +364,7 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
   //           attribute can not be inherited.
   AttributeSet OldFnAttrs = oldFunction->getAttributes().getFnAttributes();
   AttrBuilder AB(OldFnAttrs, AttributeSet::FunctionIndex);
-  for (auto Attr : AB.td_attrs())
+  for (const auto &Attr : AB.td_attrs())
     newFunction->addFnAttr(Attr.first, Attr.second);
 
   newFunction->getBasicBlockList().push_back(newRootNode);