{PING] [PATCH] Sign extension elimination

H. J. Lu hjl@lucon.org
Tue Apr 18 14:54:00 GMT 2006


On Tue, Apr 18, 2006 at 10:19:11AM +0300, Leehod Baruch wrote:
> >> > I don't think the current SEE worked well for x86-64. We have been
> >> > trying to extend it to x86-64. My main concern is when SEE is enabled,
> >> > some very odd x86-64 code is generated for some simple testcases.
> >> Can you point out, what are the testcases and what is the odd code that
> >> was generated.
> ...
> > logadd:
> >         addl    %edi, %esi
> >         movswl  %si,%eax
> >         ret
> >
> > With SEE, I got
> >
> > logadd:
> >         leal    (%rsi,%rdi), %eax
> >         cwtl
> >         ret
> >
> > I am not sure if the new one is better.
> Even if the code is not optimal, if it is correct I don't think
> that it is odd.
> 
> > The main problem for x86-64 is
> > SEE is just moving instructions around or replacing one with another.
> > For the testcase in
> >
> > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17387
> >
> > "-O2 -fsee" doesn't reduce number of total instructions at all. It
> > replaces
> Did you use the version that we are working on (with Denis' change)?
> If not, then we know what the problem is and we are on the way to fix it.
> If yes, please send me the dump file of the SEE and the one just before it
> and I'll try to see what is the problem.

Hi Leehod,

I sent you RTL dumps. I'd like to see SEE in first. Then we can make it
to work for x86-64.


H.J.



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