As pointed out recently [1], sparse is parsing -march on RISC-V in order to obtain the default set of preprocessor macros to use. Back when this was written ISA string was a simple affair, but these days it's a lot more complicated. It's going to be a big chunk of work to get a proper ISA string parser into sparse, but we can at least fix the breakages for the subset of legal ISA strings that Linux currently uses (and are breaking users). This patch set does three things: * Stops die()ing on unknown ISA strings, unless the user has passed -Wsparse-error. This prints a warning and guesses at the macros to use, which is probably fine for Linux. * Cleans up some of the differences between GCC's -march parsing and sparse's. None of this should really matter for Linux, as GCC will blow up on bad ISA strings, but it just seemed worth doing when I was in there. * Adds support for the Zicsr and Zifencei extensions, which were recently enabled. With these the unknown ISA string warning goes away for Linux builds. They're all sort of independent (and happen in this order), but they're all touching the same code so I'm just sending it as a series. It's my first time touching sparse. I've poked around with the first patch on its own and it seems to largely work as expected: I'm still getting a bunch of sparse-related warnings when I turn on sparse in my builds, but at least I don't get an error (after updating to a binutils that supports the new arguments, so Linux detects them). I tried CF="-Wsparse-error", which also behaves as expected (that trinary boolean tripped me up for a bit). The first patch alone should be a sufficient band-aid for systems that are actively broken right now, the rest are cleanups -- these may be necessary to get the RISC-V port sparse-clean, but that's a WIP so there might be more. I'm going to play around with that, but just looking at the volume of spew it's probably going to take a while. I gave these patches a bit of testing one-by-one, but not nearly as much as the first. I just spun up a sparse repo [2] at kernel.org, these are on the riscv branch if that helps for anyone. I've also started messing around with parsing a few more of the multi-letter extensions, but there's so much coupling I got fed up -- it's on riscv-wip, but I definitely don't like that last patch. I figured it's better to send out these bits, as they look solid to me and builds are broken. The new stuff (B, K, and V) are all in GCC-12 anyway, so we have a bit of time before they're useful. [1]: https://lore.kernel.org/linux-sparse/mhng-c280d48c-477d-4589-baee-255c774b5a51@palmer-mbp2014/T/#maef705f448e4a1f12d853c0d8bc756f037ce1ce0 [2]: https://git.kernel.org/pub/scm/linux/kernel/git/palmer/sparse.git
