Re: On inlining in C++

[Andrew Pinski <pinskia at physics dot uc dot edu>]

On Tuesday, Aug 5, 2003, at 22:00 US/Eastern, Joe Buck wrote:

> > > There are tons of messages in this (or related thread) so it might be
> > > possible that I missed a message that disagreed with the
> > > interpretation of the documentation I quoted.  Can you give reference
> > > to such a message?
>
> On Tue, Aug 05, 2003 at 11:16:56AM -0700, Geoff Keating wrote:
> > I would point out that the documentation says "as fast as a macro",
> > but it should really say "as fast or faster than a macro".
>
> Ah, but even if we fix the inlining issues, we still aren't keeping the
> promise: inline functions are still slower in many cases if 
> struct/class
> objects with more than one member are passed by reference.
 (but that macro is not equivalent to that function).
> Compile the following code with "gcc -O2 -S il.C" using the trunk on 
> x86,
> and take a look.  The problem is that we prematurely commit the tmp 
> object
> to the stack, even though after inlining its address is not taken.

Yes this is a know defect in gcc which should be fixed soon on the 
tree-ssa branch,
it is not yet but it should be soon.

Thanks,
Andrew Pinski