[llvm-dev] Segfault in llc 3.8.0 building GHC

[Justin Bogner via llvm-dev]

Davide Italiano via llvm-dev <llvm-dev at lists.llvm.org> writes:
> On Fri, Oct 21, 2016 at 6:19 AM, Shea Levy via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> Hi all,
>>
>> I'm hitting a segfault in llc when trying to build GHC:
>> http://sprunge.us/ZVGB. What is the best way to debug this? I'm able to
>> bump to 3.8.1 if needed, but GHC tends to break when updating major
>> versions due to IR incompatibilities.
>>
>> Thanks,
>> Shea
>>
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>> llvm-dev at lists.llvm.org
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>>
>
> The stack dump contains the program arguments so you should be able to
> reproduce the crash yourself.
>
> 0. Program arguments:
> /nix/store/izlawmnrzpk5sbr62c757cxay0kdlgam-llvm-3.8.0/bin/llc -O3
> -relocation-model=dynamic-no-pic
> /private/tmp/nix-build-ghc-8.1.201601019.drv-3/ghc37608_0/ghc_5.bc -o
> /private/tmp/nix-build-ghc-8.1.201601019.drv-3/ghc37608_0/ghc_6.lm_s
> --enable-tbaa=true -mattr=+v7,+vfp3
> [...]
> 1. Running pass 'Function Pass Manager' on module
> '/private/tmp/nix-build-ghc-8.1.201601019.drv-3/ghc37608_0/ghc_5.bc'.
> 2. Running pass 'Prologue/Epilogue Insertion & Frame Finalization' on
> function '@"stg_unmaskAsyncExceptionszh_ret_info$def"'
>
> If you're able to repro, I recommend to get LLVM trunk from svn and
> see if you can still reproduce, and report a bug in that case (or if
> it doesn't, backport the commit(s) that fixed).

Note that bitcode is forward-compatible, so ghc_5.bc should be readable
by LLVM trunk, even if the textual IR might not be.