[llvm-dev] LLVM Error: Unsupported library call operation

[div code via llvm-dev]

Any one can shed some light on this? I still cannot figure a principled way
to interpret the error msg. Thanks a lot.

Best,
Irene

On Fri, Dec 14, 2018 at 3:50 PM div code <divsubmission at gmail.com> wrote:

> Hello Philip,
>
> Thank you so much for the info. These legacy LLVM IR code is not produced
> on my side so I don't even know the version of the compiler they use..
>
> I tried to do some "delta debugging" and eventually locate the buggy line
> of the code. So as shown below, the following code cause llc (version
> 3.8.1) throws the "Unsupported library call operation" issue, but it works
> fine for llc version 3.9.
>
>
>   %10 = call i256 @llvm.bswap.i256(i256 %9)
>   %11 = call i256 @llvm.ctlz.i256(i256 0, i1 false)
>   %lz22 = trunc i256 %11 to i64
>   %sigBits23 = sub i64 256, %lz22
>   %12 = add i64 %sigBits23, 7
>   %13 = udiv i64 %12, 8
>   %14 = mul nuw i64 %13, 10*  call void @test.check(i64* %gas.ptr, i64 %14, i8* %jmpBuf)
>   %15 = call i256 @test.udiv.i256(i256 %10, i256 1) <-- this seems fine*
>
>
>   ...
>   %20 = call i256 @llvm.bswap.i256(i256 %msg.value)*  %21 = mul i256 %20, 190
>   %22 = call i256 @test.udiv.i256(i256 %21, i256 100) <--- this cause the issue for llc 3.8.1
> *
> define private i256 @test.udiv.i256(i256 %x, i256 %y) {
>   %1 = call <2 x i256> @evm.udivrem.i256(i256 %x, i256 %y)
>   %2 = extractelement <2 x i256> %1, i64 0
>   ret i256 %2
> }
>
>
> I tried to tweak the buggy lines into the following code, and it can also
> pass the compilation:
>
>
>   %20 = call i256 @llvm.bswap.i256(i256 %msg.value)
>   %21 = call i256 @test.udiv.i256(i256 %20, i256 100)
>
>
> This seems really wired to me.. Any idea on that? Thank you!
>
> Best,
> Irene
>
>
>
> On Fri, Dec 14, 2018 at 1:20 PM Philip Pfaffe <philip.pfaffe at gmail.com>
> wrote:
>
>> Hi Irene,
>>
>> the error means that the IR contains a call to a runtime library function
>> that the backend doesn't know as of 3.8. You probably created the IR with a
>> different llvm version than tha.
>>
>> Cheers,
>> Philip
>>
>> On Fri, Dec 14, 2018 at 11:27 AM div code via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hello,
>>>
>>> I am on the hook to instrument a piece of legacy LLVM IR code, and then
>>> we are planning to feed to the SeaHorn framework for some model checking
>>> tasks.
>>>
>>> After the instrumentation, I tried to use llc (version 3.9) to compile
>>> the IR code, and it works fine. However, when I try to use llc (version
>>> 3.8.1, the default llvm version of SeaHorn) to compile the IR code, it
>>> shows the following error:
>>>
>>> LLVM ERROR: Unsupported library call operation!
>>>
>>> I can dig into the IR code and do some "alpha debugging" to see which
>>> part of the IR leads to such issue; however, our legacy code is quite large
>>> so it could take a while.. Also, I really have no idea on what is "library
>>> call operation".. Does it mean some external declared functions? In the IR
>>> code we have quite a lot of that.
>>>
>>> So could anyone shed some light on this? What would be the general cause
>>> of this issue? Thank you. Any advice or suggestions would be appreciated.
>>>
>>> Best,
>>> Irene
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
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