[mlir] Compare elements directly rather than creating pair first

[jpienaar]

Summary

This avoided some conversion overhead on a model in TypeUniquer.

[rriddle]

Thanks!

Can you clarify in the description that the conversion is from ArrayRef -> TypeRange? The description is a little difficult to parse right now.

mlir/lib/IR/TypeDetail.h

struct FunctionTypeStorage : public TypeStorage {
   FunctionTypeStorage(unsigned numInputs, unsigned numResults,
                       Type const *inputsAndResults)
       : numInputs(numInputs), numResults(numResults),
         inputsAndResults(inputsAndResults) {}
 
   /// The hash key used for uniquing.
   using KeyTy = std::pair<TypeRange, TypeRange>;
   bool operator==(const KeyTy &key) const {
-    return key == KeyTy(getInputs(), getResults());
+    if (std::get<0>(key) == getInputs())
+      return std::get<1>(key) == getResults();
+    return false;
   }
 
   /// Construction.
   static FunctionTypeStorage *construct(TypeStorageAllocator &allocator,
                                         const KeyTy &key) {
     TypeRange inputs = key.first, results = key.second;
 
     // Copy the inputs and results into the bump pointer.