[committed] canonicalize LE comparisons

[Ian Lance Taylor]

Eric Christopher <echristo@redhat.com> writes:

> +  HOST_WIDE_INT original, plus_one;
> +
> +  if (GET_CODE (*cmp1) != CONST_INT)
> +    return false;
> +  
> +  original = INTVAL (*cmp1);
> +  plus_one = trunc_int_for_mode (original + 1, mode);
> +  
> +  switch (*code)
> +    {
> +    case LE:
> +      if (original < plus_one)

Since we've been just talking about it at length, aren't you relying
on signed integer overflow here?  If HOST_WIDE_INT is 4 bytes, and
original == 0x7fffffff, you seem to be assuming that original + 1 ==
0x80000000 < 0.  That is signed integer overflow, which is undefined
according to the C standard.

Or am I missing something?

Ian