[llvm-dev] Miscompilation bugs in GVN.cpp and PromoteMemoryToRegister.cpp?

[Jeehoon Kang via llvm-dev]

First of all, thank you for your input :)  As many of you said, my question
was somewhat vague.  I'd like to clarify what we want to know, and what we
did.


We're enumerating all the miscompilation bugs in the mem2reg and gvn passes
(but not in the analysis passes they depend on), which was discovered after
the release of LLVM 3.7.1 (5th Jan 2016).
That's why I specifically asked about the bugs in GVN.cpp and
PromoteMemoryToRegister.cpp.

In order to know that, we searched "sroa", "mem2reg",
"PromoteMemoryToRegister", and "gvn" in the LLVM bugzilla.
By manually inspecting the entire search result, we could find a handful of
such bugs.

However, searching bugzilla may miss some bugs.  A bug may not be reported
in the bugzilla, but be patched in the trunk directly.
We'd like to know whether there are such bugs.


So I'd like to ask if you know any miscompilation bug that is (1) in
PromoteMemoryToRegister.cpp or GVN.cpp; (2) discovered after the release of
LLVM 3.7.1; *and* (3) not reported in the LLVM bugzilla.


I'm sorry that I asked a vague question.  I hope this email clarifies my
question.  Also thank you again for valuable comments!

Best,
Jeehoon




2018-04-11 4:21 GMT+09:00 Andrew Kelley via llvm-dev <
llvm-dev at lists.llvm.org>:

>
>
> On Tue, Apr 10, 2018 at 3:09 PM, Daniel Berlin via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>>
>>
>> On Tue, Apr 10, 2018 at 10:28 AM, Friedman, Eli via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> On 4/9/2018 8:19 PM, Jeehoon Kang via llvm-dev wrote:
>>>
>>> Dear llvm-dev,
>>>
>>>
>>> Hi!  We're collecting mis-compilation bugs in gvn and mem2reg since
>>> 3.7.1.  Specifically, We're interested in bugs in the following files:
>>>
>>> llvm/lib/Transforms/Scalar/GVN.cpp
>>> llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
>>>
>>>
>>> 3.7 was released over two years ago; there have been many bugfixes to
>>> both GVN and the analysis passes it depends on since then.  Do you have
>>> some idea of what, specifically, you're looking for?
>>>
>>> mem2reg is a very simple pass; I would be surprised if you found
>>> miscompile bug in it.
>>>
>>
>> There are definitely a few miscompile bugs floating around in the edge
>> cases of mem2reg.
>>
>
> Here's one: https://bugs.llvm.org/show_bug.cgi?id=36578
>
>
>>
>>
>> On Tue, Apr 10, 2018 at 10:28 AM, Friedman, Eli via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> On 4/9/2018 8:19 PM, Jeehoon Kang via llvm-dev wrote:
>>>
>>> Dear llvm-dev,
>>>
>>>
>>> Hi!  We're collecting mis-compilation bugs in gvn and mem2reg since
>>> 3.7.1.  Specifically, We're interested in bugs in the following files:
>>>
>>> llvm/lib/Transforms/Scalar/GVN.cpp
>>> llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
>>>
>>>
>>> 3.7 was released over two years ago; there have been many bugfixes to
>>> both GVN and the analysis passes it depends on since then.  Do you have
>>> some idea of what, specifically, you're looking for?
>>>
>>> mem2reg is a very simple pass; I would be surprised if you found
>>> miscompile bug in it.
>>>
>>> -Eli
>>>
>>> --
>>> Employee of Qualcomm Innovation Center, Inc.
>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>>>
>>>
>>> _______________________________________________
>>> 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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>


-- 
Jeehoon Kang (Ph.D. student) <http://sf.snu.ac.kr/jeehoon.kang>
Software Foundations Laboratory <http://sf.snu.ac.kr>
Seoul National University <http://www.snu.ac.kr>
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