BOOST_FOREACH less efficient than handcoded loop for some testcases

[Erik]

I made some tests of BOOST_FOREACH (from boost-1.34) to see if it
generates as good code as a handcoded loop. The answer is that it does
under certain circumstances. I tested g++-4.2.0 and g++-4.1.2 and the
optimizations levels O3, O2 and Os. Here is the first testcase (where a
reference to the vector is passed as a parameter):

//////////////////////////////////////////////////////////////////////////////

void f(float);
#include <boost/foreach.hpp>
#include <vector>

void g(const std::vector<float> & v) {

   BOOST_FOREACH(float i, v)
      f(i);
}

//////////////////////////////////////////////////////////////////////////////

This is as efficient as a handcoded loop if and only if the g++ version is 4.2.0 and the optimization level is O3. There will be 21 assembly instructions.

Here is the other testcase:
//////////////////////////////////////////////////////////////////////////////
void f(float);
#include <boost/foreach.hpp>
#include <vector>

struct A {
   void g() const;
   char name[52];
   std::vector<float> const v;
};

void A::g() const {

   BOOST_FOREACH(float i, v)
      f(i);
}
//////////////////////////////////////////////////////////////////////////////

Unfortunately this gives as much as 24 instructions, while then handcoded version still gives only 21 instructions.

I attach the script I used for testing. If you want to try it yourself, put the script in an empty directory and run from there; it will create some files. After running it, it may be interesting to compare the generated code, for example:
diff -dU2 iterate_vector-member-g++-4.2.0-O3.s BOOST_FOREACH-member-g++-4.2.0-O3.s|kompare -

Can gcc be fixed so that it optimizes BOOST_FOREACH to be as efficient as a handcoded loop? Should I report it to the bugtracker?

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