Re: [PATCH] [4.0] Fix performance regressions due to inlining

[Jeffrey A Law <law at redhat dot com>]

On Fri, 2005-03-04 at 08:39 -0800, Mark Mitchell wrote:
> Richard Guenther wrote:
> 
> > patch one: ignore stores to DECL_IGNORED variables in estimate_num_insns
> > patch two: adjust inlining limits to 10% below the 3.4 values
> > patch three: make cost of CALL_EXPR depend on size of arguments
> > patch four: do not allow shrinking of unit size due to inlining
> 
> >  #1 is patches one and two
> >  #2 is #1 + patch three
> >  #3 is #1 + patch four
> 
> > How do I need to proceed to get #2 considered for 4.0?  Can someone
> > throw SPEC at that combination?  Does anyone have stuff like PR8361
> > that includes _run_-time testing?
> 
> I don't understand patch one.  (Not "#1", "patch one".)  Why don't 
> stores to DECL_IGNORED variables matter?  I understand why this helps 
> certain codes, but it seems like a hack, rather than a conceptually 
> sound change.  I understand that you're trying to avoid counting nodes 
> that won't actually result in code generation, but I don't think this 
> approach is sound.
Agreed.  Just because DECL_IGNORED is set does not mean the statement
is going to generate no code.  It merely means the LHS of the
assignment is a compiler generated temporary -- it does _not_ correspond
to whether or not the assignment is going to generate code.

jeff