msp430 internal error ASG

The standalone reduced code below produces the following diagnostic with msp430-4.1.1 and msp430-4.1.2 under Linux:

char *
xtoa (long long sval,
      char * str,
      int radix)
{
  unsigned long long uval;
  char *sp = str;

  do {
    char rem = uval % radix;
    uval /= radix;
    if (10 > rem) {
      *sp++ = '0' + rem;
    } else {
      *sp++ = 'A' + rem - 10;
    }
  } while (0 < uval);

  return str;
}

Build with:

llc[1242]$ cl430 --relaxed_ansi  -c /tmp/x.c
 /tmp/x.c, line 10: INTERNAL ERROR: no match for ASG


This may be a serious problem.  Please contact customer support with a
description of this problem and a sample of the source files that caused this
INTERNAL ERROR message to appear.

Cannot continue compilation - ABORTING!


 Compilation failure