Hi Dylan,
the following code
volatile uint8_t v1;
volatile uint8_t v2;
__attribute__((interrupt)) void __vector_21(void) {
v2 = v1;
}
produces in C mode:
00000092 <__vector_21>:
92: 80 91 61 00 lds r24, 0x0061 ; 0x800061 <v1>
96: 80 93 60 00 sts 0x0060, r24 ; 0x800060 <__data_end>
9a: 08 95 ret
and in C++ mode:
00000074 <_Z11__vector_21v>:
74: 80 91 60 00 lds r24, 0x0060 ; 0x800060 <__data_end>
78: 80 93 61 00 sts 0x0061, r24 ; 0x800061 <v2>
7c: 08 95 ret
So, in C++ mode it is not recognized as ISR due to name mangling.
Furthermore there are no register push/pos and no reti.
Whats wrong?
Thanks.
Am 11.03.20 um 08:13 schrieb Dylan McKay:> Here you go Wilhelm,
>
> https://github.com/dylanmckay/clang-avr-libc-interrupt-example
>
>
>
> On Thu, Mar 5, 2020 at 4:05 AM Wilhelm Meier <wilhelm.meier at hs-kl.de
> <mailto:wilhelm.meier at hs-kl.de>> wrote:
>
> Am 04.03.20 um 13:28 schrieb Dylan McKay:
>
> >
> > * *The C/C++ function needs to be declared with either the
calling
> > convention avr-interrupt or avr-non-blocking-interrupt.*
Skipping
> > this step will cause regular ret instructions to be emitted
for
> > return-from-subroutine, instead of the required reti for
interrupt
> > handlers. ISRs also have stricter requirements on which
registers
> > must not be clobbered after execution, which the backend will
> handle
> > properly by restoring all clobbered registers in the interrupt
> > handler epilogue
> > * *The symbol names of the ISR function handlers must match
those
> > referred to in avr-libc/avr-libgcc/crt*. This is because the
ISR
> > table is specified in assembly inside the GCC AVR CRT. The way
it
> > works is that the external symbol references in the CRT object
> files
> > are declared with an exotic linkage type that causes the
linker to
> > skip linking of the symbols if they are undefined references.
> If you
> > chose a custom ISR table in a custom CRT or runtime library,
you
> > would be free to choose ISR names as you pleased.
> >
> Thank you for your explanation. But I suspect I didn't get it
right. Can
> you please provide an example?
>
> Thanks
>
Answering partly to myself there was a extern "C" missing. But the register pushes ans reti are still missing. Whats wrong? Am 28.03.20 um 06:26 schrieb Wilhelm Meier via llvm-dev:> Hi Dylan, > > the following code > > volatile uint8_t v1; > volatile uint8_t v2; > > __attribute__((interrupt)) void __vector_21(void) { > v2 = v1; > } > > produces in C mode: > > 00000092 <__vector_21>: > 92: 80 91 61 00 lds r24, 0x0061 ; 0x800061 <v1> > 96: 80 93 60 00 sts 0x0060, r24 ; 0x800060 <__data_end> > 9a: 08 95 ret > > and in C++ mode: > > 00000074 <_Z11__vector_21v>: > 74: 80 91 60 00 lds r24, 0x0060 ; 0x800060 <__data_end> > 78: 80 93 61 00 sts 0x0061, r24 ; 0x800061 <v2> > 7c: 08 95 ret > > So, in C++ mode it is not recognized as ISR due to name mangling. > > Furthermore there are no register push/pos and no reti. > > Whats wrong? > > Thanks. > > > Am 11.03.20 um 08:13 schrieb Dylan McKay: >> Here you go Wilhelm, >> >> https://github.com/dylanmckay/clang-avr-libc-interrupt-example >> >> >> >> On Thu, Mar 5, 2020 at 4:05 AM Wilhelm Meier <wilhelm.meier at hs-kl.de >> <mailto:wilhelm.meier at hs-kl.de>> wrote: >> >> Am 04.03.20 um 13:28 schrieb Dylan McKay: >> >> > >> > * *The C/C++ function needs to be declared with either the calling >> > convention avr-interrupt or avr-non-blocking-interrupt.* Skipping >> > this step will cause regular ret instructions to be emitted for >> > return-from-subroutine, instead of the required reti for interrupt >> > handlers. ISRs also have stricter requirements on which registers >> > must not be clobbered after execution, which the backend will >> handle >> > properly by restoring all clobbered registers in the interrupt >> > handler epilogue >> > * *The symbol names of the ISR function handlers must match those >> > referred to in avr-libc/avr-libgcc/crt*. This is because the ISR >> > table is specified in assembly inside the GCC AVR CRT. The way it >> > works is that the external symbol references in the CRT object >> files >> > are declared with an exotic linkage type that causes the linker to >> > skip linking of the symbols if they are undefined references. >> If you >> > chose a custom ISR table in a custom CRT or runtime library, you >> > would be free to choose ISR names as you pleased. >> > >> Thank you for your explanation. But I suspect I didn't get it right. Can >> you please provide an example? >> >> Thanks >> > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >
Hey Wilhelm, Could you post the LLVM IR generated from your C++ file? This can be achieved with 'clang -S -emit-llvm' Cheers On Sat, Mar 28, 2020 at 6:36 PM Wilhelm Meier <wilhelm.meier at hs-kl.de> wrote:> Answering partly to myself there was a extern "C" missing. > > But the register pushes ans reti are still missing. > > Whats wrong? > > Am 28.03.20 um 06:26 schrieb Wilhelm Meier via llvm-dev: > > Hi Dylan, > > > > the following code > > > > volatile uint8_t v1; > > volatile uint8_t v2; > > > > __attribute__((interrupt)) void __vector_21(void) { > > v2 = v1; > > } > > > > produces in C mode: > > > > 00000092 <__vector_21>: > > 92: 80 91 61 00 lds r24, 0x0061 ; 0x800061 <v1> > > 96: 80 93 60 00 sts 0x0060, r24 ; 0x800060 <__data_end> > > 9a: 08 95 ret > > > > and in C++ mode: > > > > 00000074 <_Z11__vector_21v>: > > 74: 80 91 60 00 lds r24, 0x0060 ; 0x800060 <__data_end> > > 78: 80 93 61 00 sts 0x0061, r24 ; 0x800061 <v2> > > 7c: 08 95 ret > > > > So, in C++ mode it is not recognized as ISR due to name mangling. > > > > Furthermore there are no register push/pos and no reti. > > > > Whats wrong? > > > > Thanks. > > > > > > Am 11.03.20 um 08:13 schrieb Dylan McKay: > >> Here you go Wilhelm, > >> > >> https://github.com/dylanmckay/clang-avr-libc-interrupt-example > >> > >> > >> > >> On Thu, Mar 5, 2020 at 4:05 AM Wilhelm Meier <wilhelm.meier at hs-kl.de > >> <mailto:wilhelm.meier at hs-kl.de>> wrote: > >> > >> Am 04.03.20 um 13:28 schrieb Dylan McKay: > >> > >> > > >> > * *The C/C++ function needs to be declared with either the > calling > >> > convention avr-interrupt or avr-non-blocking-interrupt.* > Skipping > >> > this step will cause regular ret instructions to be emitted > for > >> > return-from-subroutine, instead of the required reti for > interrupt > >> > handlers. ISRs also have stricter requirements on which > registers > >> > must not be clobbered after execution, which the backend will > >> handle > >> > properly by restoring all clobbered registers in the interrupt > >> > handler epilogue > >> > * *The symbol names of the ISR function handlers must match > those > >> > referred to in avr-libc/avr-libgcc/crt*. This is because the > ISR > >> > table is specified in assembly inside the GCC AVR CRT. The > way it > >> > works is that the external symbol references in the CRT object > >> files > >> > are declared with an exotic linkage type that causes the > linker to > >> > skip linking of the symbols if they are undefined references. > >> If you > >> > chose a custom ISR table in a custom CRT or runtime library, > you > >> > would be free to choose ISR names as you pleased. > >> > > >> Thank you for your explanation. But I suspect I didn't get it > right. Can > >> you please provide an example? > >> > >> Thanks > >> > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200331/919d9b1c/attachment-0001.html>