Re: [PATCH] [5/5] kbuild: Set -fconserve-stack option for gcc 4.5

[Sam Ravnborg <sam@ravnborg.org>]

On Mon, Sep 14, 2009 at 02:36:15PM -0700, Andrew Morton wrote:
> On Mon, 14 Sep 2009 22:18:11 +0200 (CEST)
> Andi Kleen <andi@firstfloor.org> wrote:
> 
> > 
> > The upcomming gcc 4.5 has a new -fconserve-stack option 
> > that tells the inliner to take stack frame size in account.
> > Set it if the compiler supports it.
> > 
> > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > 
> > ---
> >  Makefile |    3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > Index: linux-2.6.31-rc3-ak/Makefile
> > ===================================================================
> > --- linux-2.6.31-rc3-ak.orig/Makefile
> > +++ linux-2.6.31-rc3-ak/Makefile
> > @@ -575,6 +575,9 @@ KBUILD_CFLAGS	+= $(call cc-option,-fno-s
> >  # revert to pre-gcc-4.4 behaviour of .eh_frame
> >  KBUILD_CFLAGS	+= $(call cc-option,-fno-dwarf2-cfi-asm)
> >  
> > +# conserve stack if available
> > +KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)
> 
> Do we have any info about what effects this option has upon the
> generated code?  Text size changes, runtime stack usage changes, etc?

I merged this despite the relevant questions above was not answered.
But maybe we should wait until Andi gets back with numbers?

	Sam