Re: GCC 3.5 Plan, Take 2

[Daniel Berlin <dberlin at dberlin dot org>]

On Aug 15, 2004, at 10:40 PM, Andrew Pinski wrote:

> On Aug 15, 2004, at 6:47 PM, Mark Mitchell wrote:
>
> > We're already better than GCC 3.4 on a lot of these axes.  Right now,
> > we're probably losing a bit on compile-time, especially with
> > optimization enabled, and most people seem to think code generation is
> > about a wash.
>
> Also the reason behind the wash in code generation is because the tree 
> optimizations
> do not do much more than the current generation of RTL optimizers 
> except for SRA which
> is the single biggest win for more C++ programs.

Uh, as we've demonstrated earlier today, GVN-PRE is doing a heck of a 
lot more than the RTL level PRE.
Otherwise, the RTL level PRE would have had the same exact problem by 
now (since it doesn't have any register pressure controls either)!

Just off the top of my head.

I doubt you can make blanket statements like you did above and have 
them be anywhere near true.

You also have to realize that we are going to soon hit a point (if we 
aren't there already) where we are going to need to significantly 
improve our register allocation and scheduling behavior in order to 
actually be producing better code.
Personally, except for some aliasing issues, and high level loop nest 
optimizations (IE vectorization, unimodular transforms, etc), i'm 
pretty happy when i look at the code the middle end now produces.

Does anyone actually look at the .optimized dump these days and say 
"Wow, this is just terrible?" (as opposed to "we missed something here 
or there")?