On 17 September 2012 10:30, Laurent Desnogues
<laurent.desnog...@gmail.com> wrote:
> On Mon, Sep 17, 2012 at 1:08 AM, Aurelien Jarno <aurel...@aurel32.net> wrote:
>> +#define GEN_SHIFT(name) \
>> +static void gen_##name(TCGv dest, TCGv t0, TCGv t1) \
>> +{ \
>> + TCGv tmp1, tmp2; \
>> + tmp1 = tcg_temp_new_i32(); \
>> + tcg_gen_andi_i32(tmp1, t1, 0xff); \
>> + tmp2 = tcg_temp_new_i32(); \
>> + tcg_gen_setcondi_i32(TCG_COND_GE, tmp2, tmp1, 32); \
>> + tcg_gen_andi_i32(tmp1, tmp1, 0x1f); \
>
> I don't think the 'and 0x1f' is needed given that later you'll and
> with 0 if the shift amount is >= 32.
The TCG shift operations are undefined behaviour (not merely
undefined result) if the shift is >= 32, so we must avoid
doing that even if we're going to throw away the answer.
-- PMM
