[9] RFR (XS): loadUB2L_immI8 & loadUS2L_immI16 rules don't match some 8-bit/16-bit masks

[Vladimir Ivanov]

Dean, what do you think about the following:
   http://cr.openjdk.java.net/~vlivanov/8001622/webrev.03

Best regards,
Vladimir Ivanov

On 5/27/15 10:04 PM, Dean Long wrote:
> You should be able to use right_n_bits on x86 too, to allow the smaller
> encoding with an 8 bit immediate instead of 32.
>
> Also, for this on sparc
>
> 5791     __ set($mask$$constant, Rtmp);
>
> I believe
>
>    __ set(right_n_bits($mask$$constant, 16), Rtmp)
>
> will give the same result in fewer instructions.
>
> dl
>
> On 5/27/2015 11:19 AM, Vladimir Ivanov wrote:
>> Vladimir, Dean, thanks for the feedback.
>>
>> I like right_n_bits trick.
>> Here's an updated webrev:
>>   http://cr.openjdk.java.net/~vlivanov/8001622/webrev.02
>>
>> Got rid of immU16 since set can encode 32-bit constants.
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> On 5/23/15 7:49 AM, Dean Long wrote:
>>> Isn't this what you want:
>>>
>>> 5656 // Load Unsigned Byte (8 bit UNsigned) with 32-bit mask into Long
>>> Register
>>> 5657 instruct loadUB2L_immI(iRegL dst, memory mem, immI mask) %{
>>> 5658   match(Set dst (ConvI2L (AndI (LoadUB mem) mask)));
>>> 5659   ins_cost(MEMORY_REF_COST + DEFAULT_COST);
>>> 5660
>>> 5661   size(2*4);
>>> 5662   format %{ "LDUB   $mem,$dst\t# ubyte & 32-bit mask -> long\n\t"
>>> 5663             "AND    $dst,right_n_bits($mask, 8),$dst" %}
>>> 5664   ins_encode %{
>>> 5665     __ ldub($mem$$Address, $dst$$Register);
>>> 5666     __ and3($dst$$Register, right_n_bits($mask$$constant, 8),
>>> $dst$$Register);
>>> 5667   %}
>>> 5668   ins_pipe(iload_mem);
>>> 5669 %}
>>>
>>> dl
>>>
>>> On 5/22/2015 8:38 AM, Vladimir Ivanov wrote:
>>>> Updated webrev:
>>>>   http://cr.openjdk.java.net/~vlivanov/8001622/webrev.01
>>>>
>>>> Introduced immU8/immU16 operands on sparc.
>>>>
>>>> As a cleanup, sorted immI/immU operand declarations.
>>>>
>>>> Best regards,
>>>> Vladimir Ivanov
>>>>
>>>> On 5/22/15 6:14 PM, Vladimir Ivanov wrote:
>>>>> Thanks for looking into the fix, Roland.
>>>>>
>>>>> On 5/22/15 5:57 PM, Roland Westrelin wrote:
>>>>>>> http://cr.openjdk.java.net/~vlivanov/8001622/webrev.00
>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8001622
>>>>>>>
>>>>>>> Mask in loadUB2L_immI8 & loadUS2L_immI16 can be relaxed from
>>>>>>> immI8/immI16 to immI, since zero-extending move is used.
>>>>>>
>>>>>> The change on sparc doesn’t look good:
>>>>>> __ and3($dst$$Register, $mask$$constant, $dst$$Register);
>>>>>>
>>>>>> the and instruction cannot encode arbitrary large integer constants.
>>>>> Good catch. I missed that it is and3.
>>>>>
>>>>>> Isn’t the root of the problem that we want an unsigned 8 bit integer
>>>>>> and not a signed one?
>>>>> Yes, unsigned 8-bit integer work fine, but it can be generalized to
>>>>> arbitrary masks as well.
>>>>>
>>>>> I experimented with new operand types (immU8, immU16), but it was more
>>>>> code for no particular benefit. I can use them on sparc.
>>>>>
>>>>> Best regards,
>>>>> Vladimir Ivanov
>>>
>