[PATCH][AArch64] Add llvm-mc test for asm code generated from all LLVM IR tests

[Ana Pazos]

Hi Jiangning,

 

With this scheme you would still be testing the MC layer encoding against
the MC layer decoding, right?

You cannot guarantee your MC layer encoding and decoding are correct in this
way, since you are testing against MC layer itself.

Probably this is the reason it is discouraged in CodeGen tests.

 

Ana.

 

From: llvm-commits-bounces at cs.uiuc.edu
[mailto:llvm-commits-bounces at cs.uiuc.edu] On Behalf Of Jiangning Liu
Sent: Sunday, December 01, 2013 7:54 PM
To: Jim Grosbach
Cc: llvm-commits at cs.uiuc.edu for LLVM
Subject: Re: [PATCH][AArch64] Add llvm-mc test for asm code generated from
all LLVM IR tests

 

Jim,

 

I'm not fully convinced by Tim's explanation yet, so could you please
provide more explanation?

 

The key point of this improvement is to enlarge the testing coverage. We
don't really have a mechanism to check if all of the code generated in
CodeGen can pass MClayer yet.

 

It would be also OK if we can provide a general mechanism to ask the asm
result generated by llc in CodeGen to pass MC test.

 

This is kind of test can obviously expose some bugs, and those bugs could be
caused by either incorrect pattern match of pattern match with loose
constraint. 

 

I think it is not always easy to cover all of the scenarios in MCLayer test,
and particularly it's hard to cover every corner of negative test scenarios.
Enlarging testing coverage should be helpful to build a robust compiler
infrastructure, right?

 

As I mentioned above, we did find bugs using this test. Also, this kind of
test should be very fast, and I don't think it would increase regression
test time.

 

Looking forward to your response!

 

Thanks,

-Jiangning

 

 

 

 

2013/11/28 Tim Northover <t.p.northover at gmail.com>

Hi Jiangning,

I think this might be a layering violation (I've CCed Jim Grosbach,
who's pretty much the authority). I know that object file tests are
discouraged from CodeGen, and this seems very similar.

I think the preferred option would be to make sure any test you
believe it's usefully doing is part of the test/MC hierarchy.

Cheers.

Tim.





 

-- 

Thanks,

-Jiangning

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