From: Linus Torvalds > Sent: 31 July 2024 00:04 > > On Tue, 30 Jul 2024 at 15:44, Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxx> wrote: > > > > Does this work for you? > > It seems to at least build cleanly here, but I'm not claiming it's all > that great. > > The nested __cmp() is still rather less than optimal from an expansion > standpoint, but at least it expands only those unique temporaries. That is the main gain, IIRC Arnd did suggest splitting it but that is a relatively small gain. > [ Side note: having not looked at a lot of the resulting pre-processed > mess, I'm not convinced it really helps to make those unique names so > long. > > The whole "__UNIQUE_ID_" prefix looks good once, but to some degree > it actually hides the important part, which is the actual prefix and > the unique number. I just passed __COUNTER__ through in my min3() patch to avoid passing lots of parameters and then appended it to the name giving _x_12345 (etc). The __UNIQUE_ID_() define just seemed excessive - especially since all compiler versions support __COUNTER__. Just need to remember a relay #define since #define arguments get expanded when they are substituted not at the 'call' site. (Which is also true for __UNIQUE_ID()) That also makes it much easier to add an extra unique name. > But honestly, nobody ever looks at this part normally, so it > probably doesn't matter ] Except that when you do it is all a right PITA. Not helped by the actual name being rammed on the end. > > It might be possible to cut down on that by doing them in series > instead of nested, but I think that would require something like > generating a fourth unique name, and something along the lines of > > __auto_type u4 = __cmp(op, ux, uy); __cmp(op, u4, uz); > > as that last line. > > And no, I did *not* try that, and there might be something I'm missing. If you have to pass through a 'u4' name that could easily take longer. David > > Linus - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
