[PATCH] Speedup CONSTRAINT_LEN

[Richard Guenther]

On Sun, 1 Apr 2007, Richard Guenther wrote:

> into tm-preds.h.  With this patch genpreds.c recognizes same-length
> subcodes (we only have such at the moment, only s390 has two of them).

Actually s390 is worse, we generate

static inline size_t
insn_constraint_len_s (char fc, const char *str ATTRIBUTE_UNUSED)
{
  switch (fc)
    {
    case 'A':
        return 2;
      break;
    case 'B':
        return 2;
      break;
    case 'N':
        return 5;
      break;
    case 'O':
        return 2;
      break;
    default: break;
    }
  return 1;
}

I guess exchanging 'O' and 'C' names and 'N' and 'D' would generate 
somewhat better code.  Or even merging 'A', 'B' and 'O'.  Still the
above should be not too bad.

Richard.