more than 10 operands in `asm', but there aren't.

[Jeffrey A Law]

  In message < 199903031043.LAA23472@pauillac.inria.fr >you write:
  > I thought the "+" constraint would solve my problem with inline asm
  > complaining about too many operands.  Here's the first example I tried:
  > 
  >   asm ("adds    %0, %0, %4
  >         adcs    %1, %1, %5
  >         adcs    %2, %2, %6
  >         adc     %3, %3, %7"
  >       : "+r" (x0), "+r" (x1), "+r" (x2), "+r" (x3)
  >       : "r" (y0), "r" (y1), "r" (y2), "r" (y3)
  >       : "cc"
  >       );
  > 
  > to add two 128-bit numbers on ARM.  But it gives the:
  > 
  >   more than 10 operands in `asm'
  > 
  > 
  > error even though there are only 8 operands.  =:-(
  > 
  > Presumably the 8 are getting expanded internally into 12 before the
  > check is done.  Sure enough in stmt.c, the expand_asm_operands()
  > function does:
Correct.


  > 
  >   asm volatile (
  >        "adds    %0, %0, %3
  >         adcs    %1, %1, %4
  >         adc     %2, %2, %5"
  >       : "+r" (x0), "+r" (x1), "+r" (x2)
  >       : "r" (y0), "r" (y1), "r" (y2)
  >       : "cc"
  >       );
  > 
  > This goes through fine.  But then if I break it by accessing
  > non-existant operands %6, %7 or %8, say like this:
  > 
  >   asm volatile (
  >        "adds    %0, %0, %3
  >         adcs    %1, %1, %4
  >         adc     %2, %2, %8"
  >       : "+r" (x0), "+r" (x1), "+r" (x2)
  >       : "r" (y0), "r" (y1), "r" (y2)
  >       : "cc"
  >       );
  > 
  > then it goes through as well and produces bogus code instead of the:
  > 
  >   invalid `asm': operand number out of range
No, the error is valid.  You're not supposed to be able to access operands
outside the ones you explicitly declare.


jeff