On 22 Sep 2015, at 12:39, H.J. Lu via cfe-dev <cfe-...@lists.llvm.org> wrote: > > The center piece of my proposal is not to change how parameters > are passed in compiler. As for user experience, the feedbacks on > my proposal from our users are very positive.
Implementing the intrinsics for getting the current interrupt requires a lot of support code for it to actually be useful. For it to be useful, you are requiring all of the C code to be run with interrupts disabled (and even that doesn’t work if you get a NMI in the middle). Most implementations use a small amount of assembly to capture the interrupt cause and the register state on entry to the handler, then reenable interrupts while the C code runs. This means that any interrupts (e.g. page faults, illegal instruction traps, whatever) that happen while the C code is running do not mask the values. Accessing these values from *existing* C code is simply a matter of loading a field from a structure. I’m really unconvinced by something that something with such a narrow use case (and one that encourages writing bad code) belongs in the compiler. David
