[cfe-dev] RFC: Support x86 interrupt and exception handlers

H.J. Lu via cfe-dev cfe-dev at lists.llvm.org
Wed Sep 16 06:11:49 PDT 2015

On Wed, Sep 16, 2015 at 1:28 AM, David Chisnall
<David.Chisnall at cl.cam.ac.uk> wrote:
> On 15 Sep 2015, at 23:17, H.J. Lu via cfe-dev <cfe-dev at lists.llvm.org> wrote:
>> In my proposal, there are only 2 handlers: interrupt and exception.
>> __builtin_interrupt_data is provided to programmers to implement
>> different variants of those handlers.
> The thing that is still missing here is a use case.  Interrupt handlers in existing operating systems all contain some assembly code because they need to do complicated things, like mask interrupts long enough to get a consistent state, store things in OS-specific context switch structures, and so on.  I can’t imagine any OS using this feature in the compiler.
> Existing compilers provide similar functionality for embedded targets, where you are not running an OS, but these often rely on some assembly code shipped with the compiler to allow the C versions to work (do you intend to contribute this code to compiler-rt for x86?).  Are enough (any?) people doing bare-metal x86 embedded work for this to be a useful feature?

Yes, this feature is intended for IA MCU, which runs bare-metal/embedded
OS.  I don't know how compiler-rt will be used for this purpose.  Do you
have an example?


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