On Thu, 19 Nov 2020 08:37:35 -0600 Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> wrote: > > Note that we have a fairly extensive tradition of defining away UB with > > language extentions, -fno-strict-overflow, -fno-strict-aliasing, > > These are options to make a large swath of not correct C programs > compile (and often work) anyway. This is useful because there are so > many such programs, because a) people did not lint; and/or b) the > problem never was obvious with some other (or older) compiler; and/or > c) people do not care about writing portable C and prefer writing in > their own non-C dialect. Note, this is not about your average C program. This is about the Linux kernel, which already does a lot of tricks in C. There's a lot of code in assembly that gets called from C (and vise versa). We modify code on the fly (which tracepoints use two methods of that - with asm-goto/jump-labels and static functions). As for your point c), I'm not sure what you mean about portable C (stuck to a single compiler, or stuck to a single architecture?). Linux obviously supports multiple architectures (more than any other OS), but it is pretty stuck to gcc as a compiler (with LLVM just starting to work too). We are fine with being stuck to a compiler if it gives us what we want. -- Steve
