[U-Boot] [PATCH] powerpc/mpc85xx:Add GCC flag -fno-delete-null-pointer-checks

[Scott Wood]

On Wed, 2015-05-20 at 10:10 -0700, York Sun wrote:
> Scott,
> 
> Please comment on this patch.
> 
> York

I think this should be set treewide (as Linux does), not just for
mpc85xx.  But use cc-option to make sure that the compiler supports the
option.

-Scott

> 
> On 05/06/2015 11:07 PM, Prabhakar Kushwaha wrote:
> >  -fdelete-null-pointer-checks flag controls global dataflow analyses and
> >  eliminate useless checks for null pointers; It assume that if a pointer is
> >  checked after it has already been dereferenced, it cannot be null.
> >  This flag is enabled by default.
> > 
> >  gcc v4.9 has more optimizations added to this option. Hence it is very
> >  aggressive with GCC v4.9 series. Add -fno-delete-null-pointer-checks to
> >  disable the optimization
> > 
> > Signed-off-by: Rohit Dharmakan <rohitarulraj at freescale.com>
> > Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
> > ---
> >  arch/powerpc/cpu/mpc85xx/config.mk | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/cpu/mpc85xx/config.mk b/arch/powerpc/cpu/mpc85xx/config.mk
> > index 72c964c..2aedd24 100644
> > --- a/arch/powerpc/cpu/mpc85xx/config.mk
> > +++ b/arch/powerpc/cpu/mpc85xx/config.mk
> > @@ -5,7 +5,8 @@
> >  # SPDX-License-Identifier:	GPL-2.0+
> >  #
> >  
> > -PLATFORM_CPPFLAGS += -Wa,-me500 -msoft-float -mno-string
> > +PLATFORM_CPPFLAGS += -Wa,-me500 -msoft-float -mno-string \
> > +					-fno-delete-null-pointer-checks
> >  
> >  # -mspe=yes is needed to have -mno-spe accepted by a buggy GCC;
> >  # see "[PATCH,rs6000] make -mno-spe work as expected" on
> >