From: Linus Torvalds > Sent: 28 July 2024 23:23 > > On Sun, 28 Jul 2024 at 15:14, David Laight <David.Laight@xxxxxxxxxx> wrote: > > > > Ok, but those can't be used as array sizes or constants. > > So the temporaries don't matter. > > No, mut I don't want the insane size explosion from unnecessarily just > forcing it to use min()/max(). > > > Don't they just work with min() - if not where is the signednes mismatch? > > David - this whole discussion is BECAUSE THESE THINGS ARE A TOTAL > DISASTER WHEN USED IN DEEP MACRO EXPANSION. > > So no. It does not work - because core macros like HUGETLB_PAGE_ORDER > end up being used deep in the VM layer, and I don't want to see > another stupid multi-ten-kB line just because min() is such a pig. > > End result: I'm going to make the rule be that when you do macro > definitions using constants, then "MIN()/MAX()" is preferable simply > because it avoids the insane expansion noise. I think you still need the temporaries if values aren't constant. And you really don't want the casts unless you actually need them to do something 'useful' - unlikely especially since negative values are unusual. Now you may want to avoid the explosive nature of min(), but if MIN() (or MIN_T) evaluates its arguments twice someone will use it in the wrong place. David > > Then in normal *code* you should use min() and max(). But not for > things like macro "constants" even if those constants end up being > some computed thing. > > Linus - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
