Boost Users :
Subject: Re: [Boost-users] [bind] performance implications?
From: Peter Dimov (pdimov_at_[hidden])
Date: 2009-05-07 13:29:37
> Probably a silly question, but has anyone performed benchmarks on
> using a std::for_each(begin, end, bind(&C::f, _1)); compared to the
> hand written loop? Under the debugger I see bind adds a 4 or 5 stack
> frames between the for_each frame and the C::f frame, so I'm wondering
> if there is any overhead in these?
It depends (heavily) on the amount of inlining the compiler does. In the
simple case of
extern int N;
extern X x;
std::for_each( x, x + N, boost::bind( &X::f, _1 ) );
the loop generated by MSVC 7.1 in a release build is
mov ecx, esi
cmp esi, edi
jne SHORT $L9292
where ebx points at X::f. More complicated examples would probably carry
more overhead as the compiler inlining threshold is reached.
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