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

[sergio.martins]

Summary

No reason to create temporaries.

[silvas]

Thanks, this LGTM. Do you need me to commit this for you?

[sergio.martins]

In D29871#680819, @silvas wrote:

Thanks, this LGTM. Do you need me to commit this for you?

yes, please commit

thanks

[silvas]

r295807, thanks! (and sorry for the delay)

lib/IR/Attributes.cpp

 }
 
 bool AttrBuilder::overlaps(const AttrBuilder &B) const {
   // First check if any of the target independent attributes overlap.
   if ((Attrs & B.Attrs).any())
     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;
 
   return false;
 }
 
 bool AttrBuilder::contains(StringRef A) const {
   return TargetDepAttrs.find(A) != TargetDepAttrs.end();

lib/Transforms/Utils/CodeExtractor.cpp

Function *CodeExtractor::constructFunction(const ValueSet &inputs,
   // Inherit all of the target dependent attributes.
   //  (e.g. If the extracted region contains a call to an x86.sse
   //  instruction we need to make sure that the extracted region has the
   //  "target-features" attribute allowing it to be lowered.
   // FIXME: This should be changed to check to see if a specific
   //           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);
 
   // Create an iterator to name all of the arguments we inserted.
   Function::arg_iterator AI = newFunction->arg_begin();
 
   // Rewrite all users of the inputs in the extracted region to use the