# Julia transplant

**URL:** <https://discourse.julialang.org/t/julia-transplant/73292>\
**Category:** Internals & Design\
**Created:** [December 18, 2021, 7:50am UTC](https://discourse.julialang.org/t/julia-transplant/73292 "2021-12-18T07:50:30Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![envyslee](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/envyslee/32/32033_2.png) [@envyslee](https://discourse.julialang.org/u/envyslee)\
**Post date:** [December 18, 2021, 7:50am UTC](https://discourse.julialang.org/t/julia-transplant/73292/1 "2021-12-18T07:50:30Z")

</div>

Julia Version 1.6.3  
LLVM 11.1.0  
File: jltypes.c  
Function: typekeyvalue\_hash

I am devloping a new backend for Julia. I have made some modification for now and I got the executable file Julia in path /usr/lib/bin. Everything seems OK until running “./julia -C “native” --output-ji ~/julia/corecompiler.ji.tmp --startup-file=no --warn-overwrite=yes -g0 -O0 compiler/compiler.jl”, I got a “Segmentation fault”, I add a print before“hj = ((jl\_datatype\_t\*)jl\_typeof(kj))-\>hash;”,and get below result:

```julia
&((jl_datatype_t*)jl_typeof(kj))->hash = 0x20004b30110, (jl_datatype_t*)jl_typeof(kj) = 0x20004b300d0, kj = 0x20008c6ab40, j = 1
&((jl_datatype_t*)jl_typeof(kj))->hash = 0x20004b30c50, (jl_datatype_t*)jl_typeof(kj) = 0x20004b30c10, kj = 0x20004b89db0, j = 1
&((jl_datatype_t*)jl_typeof(kj))->hash = 0x20004cd3f50, (jl_datatype_t*)jl_typeof(kj) = 0x20004cd3f10, kj = 0x20004b40268, j = 0
&((jl_datatype_t*)jl_typeof(kj))->hash = 0x40, (jl_datatype_t*)jl_typeof(kj) = (nil), kj = 0x20004c62aa0, j = 2

```

Obviously，jl\_typeof(kj) is 0x0. It confuse me several days.Could anyone give me some guidances to solve this problem?Or maybe someone can tell me what steps exactly should I do when adding a new backend in Julia.  
Thanks a lot.

---

<div class="post-metadata">

**Author:** ![StefanKarpinski](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stefankarpinski/32/24_2.png) [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)\
**Post date:** [December 18, 2021, 1:31pm UTC](https://discourse.julialang.org/t/julia-transplant/73292/2 "2021-12-18T13:31:12Z")

</div>

Hard to say anything useful without knowing how you modified it.