lld 20 and 21 cause segmentation fault. mold and ld work. Code compiled with clang.

[mcarans]

I have updated the game Oolite to build with clang (20 or 21). It works fine on Linux when linking with ld or mold. When linking with lld 20 or 21, the resulting executable fails with a segmentation fault. Please advise.

[DhanashreePetare]

Greetings @mcarans, I am interested to work on the issue. Can you please assign it to me. Thankyou.

[shafik]

@MaskRay any advice here on what we need to help figure out the issue?

[mcarans]

@DhanashreePetare I would be happy to assign it to you, but I do not have the permissions to do so. It probably requires an LLVM dev to do it.

[hstk30-hw]

First at all, need a reproduce. Add --reproduce= for lld, to get a reproduce.

[llvmbot]

@llvm/issue-subscribers-lld-elf

Author: Mike (mcarans)

Details

I have updated the game [Oolite](https://github.com/OoliteProject/oolite/) to build with clang (20 or 21). It works fine on Linux when linking with ld or mold. When linking with lld 20 or 21, the resulting executable fails with a segmentation fault. Please advise.

[MaskRay]

Can you upload the reproduce tarball somewhere?

Either or the following command creates a reproduce tarball

clang -fuse-ld=lld -Wl,--reproduce=/tmp/rep.tar a.o b.o
LLD_REPRODUCE=/tmp/rep.tar clang -fuse-ld=lld a.o b.o

You can then unpack the tarball, navigate to the directory, and invoke LLD with the response file:

cd /tmp; tar xf rep.tar; cd rep
ld.lld @response.txt # append options like -y foo

The response file includes the --chroot option, which GNU ld does not support.
In most cases, you can simply remove this option to examine GNU ld's behavior.

ld.bfd @response.txt

[mcarans]

@MaskRay Thanks for this explanation. I did not know about the --reproduce option. Please find rep.tar file here:
https://www.filemail.com/d/jpphgknlptloyih

I confirmed after adding -Wl,--reproduce=/tmp/rep.tar that running the original executable produced by lld fails with a segmentation fault.

ld.bfd @response.txt gives ld.bfd: bad -plugin-opt option I tried deleting -plugin-opt=mcpu=x86-64 from response.txt, but that gave home/mcarans/Code/OoliteRelated/oolite_mcarans/obj.spk/oolite.obj/legacy_random.c.o: file not recognized: file format not recognized

mold @response.txt gives mold: fatal: home/mcarans/Code/OoliteRelated/oolite_mcarans/obj.spk/oolite.obj/legacy_random.c.o: unable to handle this LTO object file because the -plugin option was not provided. Please make sure you added -flto not only when creating object files but also when linking the final executable. Note that -flto was added to both compiler and linker flags.