[llvm-dev] MIR YAML deserialisation failure

[Valentin Churavy via llvm-dev]

Thank you both!

I was running into the issue that bugpoint was reducing my test-case into
other failures and I hadn't managed yet to find the right point in the
Julia pass pipeline to insert the module to reproduce the issue reliably
from llc and that's why I started looking at using the MIR.

I will go back at looking at the pass pipeline and the IR and get a
reproducer that way!

Thanks,
Valentin

On Tue, 20 Mar 2018 at 07:51 Nemanja Ivanovic <nemanja.i.ibm at gmail.com>
wrote:

> Valentin,
> in terms of limitations as Sean pointed out, an important one is that .mir
> doesn't have MachineFunctionInfo which may result in failure on accesses to
> global variables due to use of register X2. The verifier considers it an
> undefined register.
> Also, it's probably easier to reduce test cases using bugpoint starting
> from an IR test case. With the code you provided, I get a different crash
> than what you apparently get. Here are the test case and the backtrace.
>
> Test case: https://pastebin.com/fxjRtJD0
> Backtrace: https://pastebin.com/FsXMvbGK
>
> Nemanja
>
> On Mon, Mar 19, 2018 at 11:51 PM, Sean Fertile via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hello Valentin,
>>
>> To generate a mir test case i think the process is to first create an IR
>> file by passing '-S -emit-llvm' to clang, then you can feed that file into
>> llc and use stop-before to get the mir just before the if-converter pass,
>> eg: `llc -stop-before=if-converter  -simplify-mir -o test.mir test.ll`.
>>
>> Also there is a MIR language reference:
>> https://llvm.org/docs/MIRLangRef.html which has some of the limitations
>> documented, as well as tips for further simplifying the generated mir if
>> need be.
>>
>> Regards,
>> Sean
>>
>> On Mon, Mar 19, 2018 at 7:53 PM, Valentin Churavy via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hello,
>>>
>>> I am trying to isolate an assertion failure in if-converter (on PPC) and
>>> I generated a textual debuglog with:
>>>
>>> ```
>>> LLVM_ARGS=-print-before-all -print-module-scope
>>> -filter-print-funcs=japi1__require_7687
>>> ```
>>>
>>> and after splicing out the the MIR before the if-converter pass
>>> I would like to run `llc -march=ppc64le -run-pass=if-converter
>>> input.mir` so that I can start minimising the MIR.
>>>
>>> This steps fails for me with a:
>>> ```
>>> error: YAML:188:20: Unrecognized character while tokenizing.
>>> Function Live Ins: %x4
>>>                    ^
>>>
>>> error: YAML:188:1: Map value must not be empty
>>> Function Live Ins: %x4
>>> ^~~~~~~~~~~~~~~~~
>>> ```
>>>
>>> Should I expect this to work, or is some part of my workflow wrong?
>>>
>>> I put the full log and just the extracted MIR file online:
>>> https://drive.google.com/open?id=1Br0s9Qvr4tzPv8nqbnV_nWezpEH5Ci7B and
>>> would appreciate any guidance whether I should file this as a deserialiser
>>> bug.
>>>
>>> Best,
>>> Valentin
>>>
>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>>
>>
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>>
>
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