llvm dev - Dec 2015 - Question about Decoding Conflict of DisassemblerTables from TableGen

Hi All,

I have faced decoding conflict of DisassemblerTables from TableGen. I
have instructions with same encoding and different mnemonic among
different architecture versions. I have used Predicates and
AssemblerPredicates to distinguish them on Codegen and Assembler but
it does not work on Disassembler. When I look at
TableGen/FixedLenDecoderEmitter.cpp, once there is decoding conflict,
tablegen does not generate table entry. I think it means even though
there are predicates, it does not affect to the table entry. Could
someone let me know how to avoid decoding conflict in this situation?
If I missed something, please let me know.

Thanks,
JinGu Kang

Hi JinGu,

You can use different DecoderNamespace values in order to separate out different
conflict-free groups. For a simple example, look at how QPX disassembly is
handled in the PowerPC backend.

 -Hal

----- Original Message -----
> From: "jingu kang via llvm-dev" <llvm-dev at
lists.llvm.org>
> To: llvm-dev at lists.llvm.org
> Sent: Saturday, December 5, 2015 5:37:00 AM
> Subject: [llvm-dev] Question about Decoding Conflict of DisassemblerTables
from TableGen
> 
> Hi All,
> 
> I have faced decoding conflict of DisassemblerTables from TableGen. I
> have instructions with same encoding and different mnemonic among
> different architecture versions. I have used Predicates and
> AssemblerPredicates to distinguish them on Codegen and Assembler but
> it does not work on Disassembler. When I look at
> TableGen/FixedLenDecoderEmitter.cpp, once there is decoding conflict,
> tablegen does not generate table entry. I think it means even though
> there are predicates, it does not affect to the table entry. Could
> someone let me know how to avoid decoding conflict in this situation?
> If I missed something, please let me know.
> 
> Thanks,
> JinGu Kang
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> 
-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory

Great!!! It is working. Thank you very much Hal!

Sincerely,
JinGu Kang

2015-12-05 13:38 GMT+00:00 Hal Finkel <hfinkel at
anl.gov>:
> Hi JinGu,
>
> You can use different DecoderNamespace values in order to separate out
different conflict-free groups. For a simple example, look at how QPX
disassembly is handled in the PowerPC backend.
>
>  -Hal
>
> ----- Original Message -----
>> From: "jingu kang via llvm-dev" <llvm-dev at
lists.llvm.org>
>> To: llvm-dev at lists.llvm.org
>> Sent: Saturday, December 5, 2015 5:37:00 AM
>> Subject: [llvm-dev] Question about Decoding Conflict of
DisassemblerTables    from TableGen
>>
>> Hi All,
>>
>> I have faced decoding conflict of DisassemblerTables from TableGen. I
>> have instructions with same encoding and different mnemonic among
>> different architecture versions. I have used Predicates and
>> AssemblerPredicates to distinguish them on Codegen and Assembler but
>> it does not work on Disassembler. When I look at
>> TableGen/FixedLenDecoderEmitter.cpp, once there is decoding conflict,
>> tablegen does not generate table entry. I think it means even though
>> there are predicates, it does not affect to the table entry. Could
>> someone let me know how to avoid decoding conflict in this situation?
>> If I missed something, please let me know.
>>
>> Thanks,
>> JinGu Kang
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory