[avr-libc-dev] [bug #36611] _delay_loop_2 must not use constraint "w" with all targets

[Georg-Johann Lay]

URL:
  <http://savannah.nongnu.org/bugs/?36611>

                 Summary: _delay_loop_2 must not use constraint "w" with all
targets
                 Project: AVR C Runtime Library
            Submitted by: gjlayde
            Submitted on: Fr 08 Jun 2012 22:36:27 GMT
                Category: Header
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Header files
                  Status: None
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 1.8.0
           Fixed Release: None

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Details:

./include/util/delay_basic.h

implements:

void
_delay_loop_2(uint16_t __count)
{
        __asm__ volatile (
                "1: sbiw %0,1" "\n\t"
                "brne 1b"
                : "=w" (__count)
                : "0" (__count)
        );
}

This won't work for tiny tiny targets because

- they don't have SBIW
- compiler with suprt for these targets empty the register
  class associated with "w".  Thus, the compiler will throw
  an error if it sees "w".







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