-----Original Message----- From: sjg@google.com [mailto:sjg@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@konsulko.com; u- boot@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@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