Re: C++ virtual function calls

joe@sanskrit.ho.att.com (Joe Orost)
Mon, 30 Oct 1995 13:21:02 GMT

          From comp.compilers
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Newsgroups: comp.compilers
From: joe@sanskrit.ho.att.com (Joe Orost)
Keywords: C++, optimize
Organization: AT&T
References: 95-10-029
Date: Mon, 30 Oct 1995 13:21:02 GMT

I don't think it is legal to hoist the virtual function lookup
out of the loop:


for( ...) {
p->virt_func();
}


because "p" is passed to virt_func as "this", and therefore the
function could change the subtype of "p", causing a different
function to be called next time around the loop!


                                                                regards,
                                                                joe


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