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Editorial Team
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Asked: 2026-06-11T06:36:08+00:00

I’m interested in writing good code from the beginning instead of optimizing the code

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I’m interested in writing good code from the beginning instead of optimizing the code later. Sorry for not providing benchmark I don’t have a working scenario at the moment. Thanks for your attention!

What are the performance gains of using FunctionY over FunctionX?

There is a lot of discussion on stackoverflow about this already but I’m in doubts in the case when accessing sub-members (recursive) as shown below. Will the compiler (say VS2008) optimize FunctionX into something like FunctionY?

void FunctionX(Obj * pObj)
{
   pObj->MemberQ->MemberW->MemberA.function1();
   pObj->MemberQ->MemberW->MemberA.function2();
   pObj->MemberQ->MemberW->MemberB.function1();
   pObj->MemberQ->MemberW->MemberB.function2();
   ..
   pObj->MemberQ->MemberW->MemberZ.function1();
   pObj->MemberQ->MemberW->MemberZ.function2();
}

void FunctionY(Obj * pObj)
{
   W * localPtr = pObj->MemberQ->MemberW;
   localPtr->MemberA.function1();
   localPtr->MemberA.function2();
   localPtr->MemberB.function1();
   localPtr->MemberB.function2();
   ...
   localPtr->MemberZ.function1();
   localPtr->MemberZ.function2();
}
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1 Answer

  1. Editorial Team

    In case none of the member pointers are volatile or pointers to volatile and you don’t have the operator -> overloaded for any members in a chain both functions are the same.
    The optimization rule you suggested is widely known as Common Expression Elimination and is supported by vast majority of compilers for many decades.

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