On 24.02.2020 15:04, Jason Thorpe wrote: > >> On Feb 24, 2020, at 4:22 AM, Kamil Rytarowski <n54%gmx.com@localhost> wrote: >> >> A compiler once being smart enough can introduce ILL/SEGV traps into >> code that performs operations on NULL pointers. This already bitten us >> when we were registering a handler at address 0x0 for the kernel code, >> GCC changed the operation into a cpu trap. (IIRC it was in the sparc code.) > > Nonsense, I think it's fair to classify that as a bug. That sort of stuff is *not* supposed to happen if -ffreestanding is passed to the compiler. > > -- thorpej > If we use 0x0, it can be a valid pointer. If we use NULL, it's not expected to work and will eventually generate a syntax erro. UBSan as a runtime tool tries to indirectly catch the latter with the former and is prone to some rare false positives (so far not reported). If a compiler is too smart for 0x0 pointers, transforming them to abort traps, it is a compiler bug. I noted that this already happens. On 24.02.2020 15:05, Mouse wrote: > (3) If you have reason to think the C committee would be interested in > having me as a member, let me know whom to talk to. I might or might > not actually end up interested in joining, but I'd like more info. http://www.open-std.org/jtc1/sc22/wg14/
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