[LLVMdev] Why some registered passes are not available through opt?

[Duncan Sands]

Hi Dmitry,

> Sorry, then I don't understand. If I invoke backend with
> target->addPassesToEmitFile, it adds both opt and llc passes.

it would be more correct to say that llc contains IR level passes and codegen
level passes (the IR level passes do some cleaning and preparation of the IR
before the IR is lowered codegen form).  The IR level passes used by llc and
the IR level passes used by opt are not the same.

Unfortunately the set of passes used by llc cannot be adjusted, unlike with
opt where you can specify what you want in the order you want.  There is some
ongoing work to improve this, but for the moment you can't use bugpoint to
narrow down codegen problems to a particular codegen pass like you can with
opt's IR level passes.

Ciao, Duncan.

  Thus,
> PassManager contains both opt and llc passes after that. In case of
> crash, bugpoint reloads all passes from the failing pass manager to
> the separate instance of opt. If opt and llc both do not support such
> mixing, then I'm guessing I need to replace "opt" with some customized
> pass loader in bugpoint.
>
> - D.
>
> 2012/6/29 Duncan Sands <baldrick at free.fr>:
>> Hi Dmitry,
>>
>>
>>> Is it correct that opt does not understand codegen passes, but llc
>>> understands both analysis/transformation and codegen passes?
>>
>>
>> no.
>>
>> Ciao, Duncan.
>>
>>
>>   I would
>>>
>>> like to modify bugpoint to work on this end.
>>>
>>> Thanks,
>>> - D.
>>>
>>> 2012/6/29 Duncan Sands <baldrick at free.fr>:
>>>>
>>>> Hi Dima,
>>>>
>>>>> I'm trying to understand why opt tool does not know some of the
>>>>> registered passes, for example, -targetpassconfig, -gc-lowering,
>>>>> -unreachableblockelim, -unreachableblockelim, -stack-protector,
>>>>> -machinemoduleinfo. This prevents me from using bugpoint to reduce the
>>>>> crash in backend. As I understand, they should be registered and
>>>>> available through the command line in the same way as all other
>>>>> passes, shouldn't they?
>>>>
>>>>
>>>> these are codegen passes not IR passes, and thus are available from llc
>>>> not opt.
>>>>
>>>> Ciao, Duncan.
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>>