[avr-gcc-list] possible 4.1.2 bug

[John Regehr]

Hi all-

The code below, compiled with avr-gcc 4.1.2 like this

  avr-gcc -c -Os -mmcu=atmega128 prob.c

produces faulty assembly code that attempts ldi into r14.  I'm not at 
all sure that the asm is correct (didn't write it) but it seems that gcc 
shouldn't be picking an unusable register in any case.  The only other 
version I tried is 3.4.3 which has the same problem.

Figured I'd check here to see if I'm missing something silly before 
filing a bug.

John Regehr


void foo (char, char, char, char, char);

short bar (void)
{
  char a = 0;
  volatile char b = 0;
  char c = 0;
  char d = 0;
  char e = 0;
  int in;
  int out;

  foo (e, d, c, b, a);

  __asm__ ("swap %B1 \n\t"
           "swap %C1 \n\t"
           "swap %D1 \n\t"
           "ldi %A1, 0xf0 \n\t"
           "eor %D1, %C1 \n\t"
           "and %D1, %A1 \n\t"
           "eor %D1, %C1 \n\t"
           "eor %C1, %B1 \n\t"
           "and %C1, %A1 \n\t"
           "eor %C1, %B1 \n\t"
           "movw %A0, %C1 \n\t"
           : "=&r" (out) : "r" (in));

  return out;
}