From ff8076d75ace8da247b927f7de37f3ed5081b55e Mon Sep 17 00:00:00 2001 From: Patrick Georgi Date: Wed, 27 Jan 2016 08:18:16 +0100 Subject: Provide a gcc-safe zero pointer zeroptr is a linker object pointing at 0 that can be used to thwart GCC's (and other compilers') "dereferencing NULL is undefined" optimization strategy when it gets in the way. Change-Id: I6aa6f28283281ebae73d6349811e290bf1b99483 Signed-off-by: Patrick Georgi Reviewed-on: https://review.coreboot.org/12294 Tested-by: Raptor Engineering Automated Test Stand Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth --- src/include/stddef.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'src/include/stddef.h') diff --git a/src/include/stddef.h b/src/include/stddef.h index b58f645a3b..35326ed6c6 100644 --- a/src/include/stddef.h +++ b/src/include/stddef.h @@ -34,4 +34,12 @@ typedef unsigned int wint_t; #define MAYBE_STATIC static #endif +#ifndef __ROMCC__ +/* Provide a pointer to address 0 that thwarts any "accessing this is + * undefined behaviour and do whatever" trickery in compilers. + * Use when you _really_ need to read32(zeroptr) (ie. read address 0). + */ +extern void *zeroptr; +#endif + #endif /* STDDEF_H */ -- cgit v1.2.3