[14] RFR (S): 8234387: C2: Better support of operands with multiple match rules in AD files

[Vladimir Ivanov]

Hi Dean,

Actually there are many operands declared with multiple match rules.

The one which is hit the hardest (matching failures) is being added by 
8234391 [1]:

+operand vec() %{
+  constraint(ALLOC_IN_RC(dynamic));
+  match(VecX);
+  match(VecY);
+  match(VecZ);
+  match(VecS);
+  match(VecD);
+
+  format %{ %}
+  interface(REG_INTER);
+%}

But there are existing operand declarations which are affected:

operand rRegP()
%{
   constraint(ALLOC_IN_RC(ptr_reg));
   match(RegP);
   match(rax_RegP);
   match(rbx_RegP);
   match(rdi_RegP);
   match(rsi_RegP);
   match(rbp_RegP);  // See Q&A below about
   match(r15_RegP);  // r15_RegP and rbp_RegP.

   format %{ %}
   interface(REG_INTER);
%}

There was no rbp_RegP operand declared and ADLC didn't notice it since 
it didn't enumerate all the match rules.

Best regards,
Vladimir Ivanov

[1] 
https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-November/036016.html

On 20.11.2019 01:16, dean.long at oracle.com wrote:
> Hi Vladimir.  The change seems to be doing what you describe, however 
> for my curiosity, could you give an example of an operand with multiple 
> match rules?
> 
> dl
> 
> On 11/19/19 5:00 AM, Vladimir Ivanov wrote:
>> http://cr.openjdk.java.net/~vlivanov/jbhateja/8234387/webrev.00
>> https://bugs.openjdk.java.net/browse/JDK-8234387
>>
>> Though ADLC accepts operands with multiple match rules, it doesn't 
>> generate correct code to handle them except the first one.
>>
>> It doesn't cause any noticeable problems for existing code, but is a 
>> major limitation for generic vector operands (JDK-8234391 [1]).
>>
>> Proposed fix enumerates all match rules.
>>
>> Fixed some missing declarations along the way.
>>
>> Contributed-by: Jatin Bhateja <jatin.bhateja at intel.com>
>> Reviewed-by: vlivanov, sviswanathan, ?
>>
>> Testing: tier1-4 (both with and without generic vectors)
>>
>> Best regards,
>> Vladimir Ivanov
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8234391
>