On Wed, Mar 6, 2013 at 8:29 AM, Jens Rottmann <[email protected]> wrote:
> Per default, after any *ptr, GCC assumes a SEGFAULT would occur if ptr was > ==0, so if control flow does reach the following code ptr must be !=0. ==> > After any *ptr GCC will optimize away all ptr==0 or !=0 checks. I know that > because I recently hunted a related bug for a week (U-Boot, ARM, different > project) until I looked at the actual assembly code. And here I thought that no-delete-null-pointer-checks had been taken out after all the problems it caused. Silly me. I wonder how many of the gcc compiler writers understand C's original purpose :-) I was quite shocked when I read of this "optimization" some years ago. Yeah, we need to ensure -fno-delete-null-pointer-checks is set on any compiler foolish enough to implement this sort of thing. ron -- coreboot mailing list: [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
