Re: [DotGNU]gcc -O3 cannot compile engine/cvm.c

[Blair Zajac]

Gopal V wrote:
> 
> If memory serves me right, Blair Zajac wrote:
> > Compiling cvm.c fails:
> >
> > /opt/i386-linux/installed/gcc-3.2.1/bin/gcc -DHAVE_CONFIG_H -I. -I. \
> > -I../include    -I../libffi/include -fno-gcse -I../include  \
> > -I../libffi/include -I. -O3 -Wall -c cvm.c
> 
> Expected failure ... -O3 messes up the engine and tries to push the
> fast variables into the stack ... Which is what I understood ...
> 
> > Is this a bug in pnet and/or gcc?  Should this bug be reported to the gcc
> > folks?
> 
> #if defined(CVM_X86) && defined(__GNUC__) && !defined(IL_NO_ASM)
>     #define REGISTER_ASM_PC(x)              register x asm ("esi")
>     #define REGISTER_ASM_STACK(x)           register x asm ("edi")
>     #define REGISTER_ASM_FRAME(x)           register x asm ("ebx")
> 
> Does this answer your question ? ... GCC left to itself knows to manage
> correctly ... but this is obviously a low level override ... (this did
> a 15% speed gain , if pnetmark is right ...)
> 
> Live happily everafter with -O2 .. :-)
> Gopal

Thanks for the quick response.

Hmmm, maybe have a specific Makefile rule for cvm.c to s/-O3/-O2/ on
CFLAGS.  Or to have configure generate a warning if CFLAGS has -O3 in it.

Best,
Blair

-- 
Blair Zajac <address@hidden>
Web and OS performance plots - http://www.orcaware.com/orca/