#V2EX
### [Rust] Contributions to Rust and LLVM in 2025
文末广告 :)
2025
* Rust: Merged [28 PRs](https://github.com/rust-lang/rust/pulls?q=is%3Apr%20author%3Adianqk%20merged%3A2025-01-01..2025-12-31%20-label%3Arollup), reviewed [24 PRs](https://github.com/rust-lang/rust/pulls?q=is%3Apr%20merged%3A2025-01-01..2025-12-31%20assignee%3Adianqk)
* LLVM: Merged [13 PRs](https://github.com/llvm/llvm-project/pulls?q=is%3Apr%20author%3Adianqk%20merged%3A2025-01-01..2025-12-31)
2024
* Rust: Merged [40 PRs](https://github.com/rust-lang/rust/pulls?q=is%3Apr%20author%3Adianqk%20merged%3A2024-01-01..2024-12-31%20-label%3Arollup)
* LLVM: Merged [20 PRs](https://github.com/llvm/llvm-project/pulls?q=is%3Apr%20author%3Adianqk%20merged%3A2024-01-01..2024-12-31)
I have much less spare time this year because I have a baby :p. And I'm looking for a sustainable way to contribute.
I joined the Rust compiler team (in 2024! :3).
## LLVM: A performance regression in LLVM that affected Ajla and Python
This regression has been discussed elsewhere; see [lobste.rs/s/9paxz2/performance\_python\_3\_14\_tail\_call](https://lobste.rs/s/9paxz2/performance_python_3_14_tail_call).
I introduced the regression due to a limit for compile time in [llvm#78582](https://github.com/llvm/llvm-project/pull/78582).
Finally, I learned [a resolve](https://github.com/gcc-mirror/gcc/blob/7f67acf60c5429895d7c9e5df81796753e2913e0/gcc/bb-reorder.cc#L2757-L2761) from GCC, and then I fixed the regression in [llvm#114990](https://github.com/llvm/llvm-project/pull/114990) and [llvm#132536](https://github.com/llvm/llvm-project/pull/132536).
## Rust: Transforming “Clone” to “Copy”
To me, the most interesting issue is [rust#128081](https://github.com/rust-lang/rust/issues/128081).
The "Clone" method can be transformed to "Copy" in GVN. I have several PRs for this and am working on more.
The first key PR ([rust#128299](https://github.com/rust-lang/rust/pull/128299)) exposed variant miscompilations. Camille Gillot identified the root cause in [rust#147844](https://github.com/rust-lang/rust/pull/147844#issuecomment-3418734635):
> We can reason with the value behind a reference because it is UB to directly assign to the underlying local while the reference is live. We allow creating new derefs, this means *extending the liveness of references*, so we are creating UB.
## Rust: Debuginfo in MIR Basic Blocks
[rust#129931](https://github.com/rust-lang/rust/pull/129931) turns out that handling Debuginfo in MIR Basic Blocks is required. I implemented this in [rust#142771](https://github.com/rust-lang/rust/pull/142771).
This left some stuff:
* Better remapping locals for debuginfos; see [rust#147525](https://github.com/rust-lang/rust/pull/147525).
* A tracking issue: [Figure out all debugging information representations of statements #147679](https://github.com/rust-lang/rust/issues/147679).
* Add documentation for the change in the [Rust Compiler Development Guide](https://rustc-dev-guide.rust-lang.org/).
## Rust: 4 P-critical
I caused 4 P-critical issues. :(
* [Miscompilation due to MatchBranchSimplification MIR pass mixing up discriminants #124150](https://github.com/rust-lang/rust/issues/124150)
* [Panic while compiling http-body v0.4.6 with rustc 1.83.0-nightly (7042c269c 2024-09-23) #130769](https://github.com/rust-lang/rust/issues/130769)
* [Panic in nightly 1.83.0 and 1.84.0 with opt-level >= 1 when unwrapping Some variant #132353](https://github.com/rust-lang/rust/issues/132353)
* [staticlib with lto=fat now includes compiler\_builtins as llvm bitcode after rustup update #146145](https://github.com/rust-lang/rust/issues/146145)
The [rust#124150](https://github.com/rust-lang/rust/issues/124150) and [rust#132353](https://github.com/rust-lang/rust/issues/132353) are miscompilations in MIR opt. I'm investigating some translation validation tools, such as Miri, Alive2, and model checker, but I haven't made any progress. So far, I have only read Program Z3, and I have forgotten many things. Furthermore, I'm thinking about picking it up next year. :p
## Other
While reviewing PRs can be exhausting, it's also a great learning opportunity. For instance, working through PRs like [rust#142707](https://github.com/rust-lang/rust/pull/142707), [rust#143784](https://github.com/rust-lang/rust/pull/143784), [rust#136840](https://github.com/rust-lang/rust/pull/136840), and [rust#133832](https://github.com/rust-lang/rust/pull/133832) taught me a great deal.
I realize that the knowledge of the LLVM backend is essential to me, since more and more issues happened in the LLVM backend. I'm not sure how to tackle these issues, but I have begun studying *[LLVM Code Generation: A deep dive into compiler backend development](https://www.packtpub.com/en-us/product/llvm-code-generation-9781835462577)*.
MIR optimizations are still important to me. I'd like to thank [Camille Gillot](https://github.com/cjgillot) for their help on MIR.
I'm trying to immerse myself in English, and I have stopped using LLM for Chinese-to-English translation anymore. :p
I'm also learning Japanese for fun. If you are interested in anime and manga, I recommend you read [learnjapanese.moe](https://learnjapanese.moe).
---
家里没地方了 :(，卖掉我的 7950X 主机：
* CPU：AMD 7950X
* 主板：华硕 TUF GAMING B650M-PLUS
* 内存 2 条：金士顿 FURY 32G D5 6000
* 水冷：华硕 ROG STRIX 飞龙二代 360
* 硬盘：ZHITAI TiPlus7100 2TB
* 硬盘：Samsung SSD 980 PRO 2TB
* 显卡：AMD 撼讯 RX6600
* 电源：先马 XP850W 白金
* 机箱：乔思伯 松果 D31
价格 11000 。