Jiong Wang writes:
> + /* If we have
> +
> +(ior (lshiftrt A imm1) (and (ashiftrt (A imm2)) mask))
> +
> + where imm1 = imm2 + 1
> +mask = ((1 << imm1) - 1) << (mode_size (A) - imm1)
> +
> + then we may simplify this into
> +
> +(ashiftrt A imm1).
> +
> +
Suppose the following shift:
T A = (T) B << C
which met the following conditions:
* T is a signed type with 2 x word_size.
* B is with signed type with the size <= word_size.
* C + sizeof (B) < word_size.
|< T >|
| high | low |
| B shifted to |
| E
