Linux/ARM: Bus error with -O3 flag of clang/llvm-3.6 while running unit-test of .NET Core

Renato Golin via llvm-commits llvm-commits at
Sun Jun 19 07:16:07 PDT 2016

On 19 June 2016 at 06:05, Geunsik Lim <leemgs at> wrote:
> I have evaluated the effect of the latest clang/llvm version to resolve
> "unassigned access (Bus error)" issue.

Ok, so we still have the problem, but it's hard for me to reproduce
because this is a C# thing.

Can you produce an IR file that, when used with upsteram llc,
reproduces the problem?

C# IR should be no different than any other, so if you can make your
front-end generate IR at O1 and O3, we could then compare and follow
them through the back-end and see what's wrong.

I'm guessing this has to do with the ARM load-store optimization pass.

The best course of action now is to create a bug in Bugzilla,
attaching the two IRs which show the bug with upstream (non-C#) LLVM,
using "llc -triple armv7a", and copy me and compnerd at

Feel free to also include the original sources, your compilation
command line and the other information in this email.


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