RFH: _inter_-procedure optimizations "CALL_REALLY_USED_REGISTERS"

[Björn Haase]

Steven Bosscher wrote:
> In
> any case, you should assume that it is a much bigger job than just
> modifying the call expander.

Ok, I had a closer look at what is happening in present state gcc and I 
understand that it is indeed a much more complex task than I first thought. 
One Issue would be also, that it probably would be worth considering which 
other kind of information (except register clobbering information) on a 
static leaf function would be worth to be shared with the caller:

memory usage of the called function / memory clobbers, information on whether 
it's a pure function ?

Probably once one starts to try to implement kind of a database containing 
information on all the functions that are already compiled, one might make 
efforts to support all of the most useful information. Of course there always 
will be trade-offs concerning compilation time and memory consumption. 

I still would like to try my very best to look after this, but I'd prefer to 
start by scanning literature. If anyone could help me out recommending good 
articles / textbooks dealing with inter-function optimizations. It would be 
appreciated :-).

Yours,

Björn