Re: [eigen] aliasing system

[Andre Krause <post@xxxxxxxxxxxxxxxx>]

Schleimer, Ben wrote:
> Hi,
>    Won't matric.xpr().row(0) be a reference to a Matrix<double,2,2>::row?
> So couldn't we still check if it's memory location is the same as any of the expressions on the
> right side and if so, set an alias flag? Like:
>
> void _ET_magic_generated_func(M& u, const M& v, const M& w)
> {
>     if(&u == &v || &u == &w)
> {

even if it would be possible, an "IF" conditional branch is a very bad 
idea, except in debug mode. for release / optimized, final code it is 
the badest thing you can do to a prozessor: afaik conditional branches 
would stall the processor pipeline and cause huge speed impacts.