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

[Kushwaha Prabhakar]

> -----Original Message-----
> From: sjg at google.com [mailto:sjg at google.com] On Behalf Of Simon Glass
> Sent: Tuesday, June 30, 2015 8:28 PM
> To: Kushwaha Prabhakar-B32579
> Cc: Wood Scott-B07421; Sun York-R58495; trini at konsulko.com; u-
> boot at lists.denx.de; Dharmakan Rohit-B30502
> Subject: Re: [PATCH] powerpc/mpc85xx:Add GCC flag -fno-delete-null-
> pointer-checks
> 
> Hi,
> 
> On 29 June 2015 at 22:18, Kushwaha Prabhakar <prabhakar at freescale.com>
> wrote:
> > Hi Simon, Tom,
> >
> > -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. It is also well documented in the GCC v4.9
> release notes:
> > https://gcc.gnu.org/gcc-4.9/porting_to.html
> >
> > There is possibility after moving to gcc-4.9 some platform may/may not
> work properly.
> > I tested this patch for freescale powerpc platforms.
> > But It may needs be taken care by all architecture like ARM, powerpc.
> > If this is the case; this flag should be in top level Makefile (not
> > sure)
> >
> 
> I suspect a top-level option would be best, perhaps near this one in Makefile:
> 
> KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
> 

I agree to put it here. 

But how to test it against different platform supported by u-boot.  

--prabhakar