Re: How to profile a VC++ program?

From:

Tamas Demjen <tdemjen@yahoo.com>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 02 May 2006 10:08:41 -0700

Message-ID:

<#WZOSsgbGHA.1112@TK2MSFTNGP05.phx.gbl>

fastgo@gmail.com wrote:

Thanks for the tips. I tried VTune evaluation version. The result is a
little bit wierd. Those inline getter methods are taking much longer
time than they would take under gcc.

Getter functions returning classes are hard to optimize, and often the
convenient getter functions are suboptimal, because returning a class by
value involves making a copy.

If it's possible, you can try to return values by reference, like this:

class A
{
public:
    std::string SlowGetter() const { return s; }
    const std::string& FastGetter() const { return s; }
private:
    std::string s;
};

It's not always possible, like in this case:
    std::string GetPathName() const { return dir + "\" + path; }

In this case a less convenient getter function has a chance to be faster:
    void GetPathName(std::string& s)
    {
       s.reserve(dir.size() + 1 + path.size());
       s = dir; s += "\"; s += path;
    }

Andrei Alexandrescu has an article about optimizing return values from
functions:

http://www.ddj.com/dept/cpp/184403855

Tom