[llvm-dev] LLC Version 3.8 : Unsupported library call operation for a mul instruction

[Alberto Barbaro via llvm-dev]

Hi Irene,
I'm absolutely not but have you tried to compile your .c project using -O3
-march=native and see that call to bswap is not present after? Are we sure
that bswap was present in version 3.8.1?

Thanks

On Sun, Dec 16, 2018, 17:47 div code via llvm-dev <llvm-dev at lists.llvm.org
wrote:

> Hello List,
>
> 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 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.
>
>   %20 = call i256 @llvm.bswap.i256(i256 %msg.value)
>   %21 = mul i256 %20, 190
>
> 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 = add i256 %20, 190
>
> This seems really wired to me.. Any idea on that? Thank you!
>
>
> Best,
>
> Irene
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