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

[Dean Long]

Looks good.

dl

On 5/28/2015 10:40 AM, Vladimir Ivanov wrote:
> 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
>>>>
>>