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Re: [avr-gcc-list] Unused registers saves/restores ?
From: |
E. Weddington |
Subject: |
Re: [avr-gcc-list] Unused registers saves/restores ? |
Date: |
Mon, 9 Jun 2003 23:03:45 GMT |
> 10 Jun 2003 09:20 Eric wrote:
> > > 10 Jun 2003 08:12 Eric wrote:
> > > > > Hello all,
> > > > >
> > > > > Compiler:
> > > > > avr-gcc --version
> > > > > avr-gcc (GCC) 3.3.1 20030519 (prerelease)
> > > > >
> > > > > Programm:
> > > > > typedef struct { long a; int b; } lo_in;
> > > > >
> > > > > lo_in foo_lo_in (void)
> > > > > {
> > > > > lo_in x;
> > > > > x.a = 1;
> > > > > x.b = 2;
> > > > > return x;
> > > > > };
> > > > >
> > > > > Compile with:
> > > > > avr-gcc -O3 -S foo_lo_in.c
> > > > >
> > > > > Result: r2,3,4,7,... not used, but saved/restored:
> > > >
> > > > Do you get the same with other optimizations?
> >
> > Including -Os?
> >
> > > > Eric
> > >
> > > avr-gcc -Os -S foo_lo_in.c ==> roughly the same
> >
>
> > Is there an optimization level where it doesn't produce
a
> > problem? (i.e. -O0, -O1, -O2)
> >
> > Eric
>
> avr-gcc -O0 -S ==> best result:
> /* File "foo_lo_in.c": code 75 = 0x004b ( 40),
prologues 18, epilogues
> 17 */
> Body is greate, but prologue/epilogue small.
>
Unless anyone else (Denis? Marek?) has any other comments
to add, I would suggest filing a GCC bug report:
<http://gcc.gnu.org/bugzilla/>
Eric Weddington
Re: [avr-gcc-list] Unused registers saves/restores ?, E. Weddington, 2003/06/09