From: Linus Torvalds > Sent: 27 February 2022 21:05 ... > And then the C standards people decided that "because our job isn't to > describe all the architectural issues you can hit, we'll call it > undefined, and in the process let compiler people intentionally break > it". > > THAT is a problem. I'm waiting for them to decide that memset(ptr, 0, len) of any structure that contains a pointer is UB (because a NULL pointer need not be the all zero bit pattern) so decide to discard the call completely (or some such). Non-zero NULL pointers is the only reason arithmetic on NULL pointers isn't valid. Or maybe that character range tests are UB because '0' to '9' don't have to be adjacent - they are even adjacent in EBCDIC. Some of the 'strict aliasing' bits are actually useful since they let the compiler reorder reads and writes. But the definition is brain-dead. Sometimes it would be nice to have byte writes reordered, but even using int:8 doesn't work. I have never worked out what 'restrict' actually does, in any places I've tried it did nothing. Although I may have been hoping it would still help when the function got inlined. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
