From 0d300ac678cfc69724861c7c94c3daa3eb15fac1 Mon Sep 17 00:00:00 2001 From: "Celina G. Val" Date: Fri, 13 Sep 2024 14:01:02 -0700 Subject: [PATCH] Update StableMIR doc to reflect current status We no longer use git subtree, and we have 2 different crates. --- compiler/stable_mir/README.md | 102 +++++----------------------------- 1 file changed, 14 insertions(+), 88 deletions(-) diff --git a/compiler/stable_mir/README.md b/compiler/stable_mir/README.md index 31dee955f49..89f610e110e 100644 --- a/compiler/stable_mir/README.md +++ b/compiler/stable_mir/README.md @@ -1,93 +1,25 @@ -This crate is regularly synced with its mirror in the rustc repo at `compiler/rustc_smir`. +This crate is currently developed in-tree together with the compiler. -We use `git subtree` for this to preserve commits and allow the rustc repo to -edit these crates without having to touch this repo. This keeps the crates compiling -while allowing us to independently work on them here. The effort of keeping them in -sync is pushed entirely onto us, without affecting rustc workflows negatively. -This may change in the future, but changes to policy should only be done via a -compiler team MCP. - -## Instructions for working on this crate locally - -Since the crate is the same in the rustc repo and here, the dependencies on rustc_* crates -will only either work here or there, but never in both places at the same time. Thus we use -optional dependencies on the rustc_* crates, requiring local development to use - -``` -cargo build --no-default-features -Zavoid-dev-deps -``` - -in order to compile successfully. - -## Instructions for syncing - -### Updating this repository - -In the rustc repo, execute - -``` -git subtree push --prefix=compiler/rustc_smir url_to_your_fork_of_project_stable_mir some_feature_branch -``` - -and then open a PR of your `some_feature_branch` against https://github.com/rust-lang/project-stable-mir - -### Updating the rustc library - -First we need to bump our stack limit, as the rustc repo otherwise quickly hits that: - -``` -ulimit -s 60000 -``` - -#### Maximum function recursion depth (1000) reached - -Then we need to disable `dash` as the default shell for sh scripts, as otherwise we run into a -hard limit of a recursion depth of 1000: - -``` -sudo dpkg-reconfigure dash -``` - -and then select `No` to disable dash. - - -#### Patching your `git worktree` - -The regular git worktree does not scale to repos of the size of the rustc repo. -So download the `git-subtree.sh` from https://github.com/gitgitgadget/git/pull/493/files and run - -``` -sudo cp --backup /path/to/patched/git-subtree.sh /usr/lib/git-core/git-subtree -sudo chmod --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree -sudo chown --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree -``` - -#### Actually doing a sync - -In the rustc repo, execute - -``` -git subtree pull --prefix=compiler/rustc_smir https://github.com/rust-lang/project-stable-mir smir -``` - -Note: only ever sync to rustc from the project-stable-mir's `smir` branch. Do not sync with your own forks. - -Then open a PR against rustc just like a regular PR. +Our goal is to start publishing `stable_mir` into crates.io. +Until then, users will use this as any other rustc crate, via extern crate. ## Stable MIR Design The stable-mir will follow a similar approach to proc-macro2. It’s -implementation will eventually be broken down into two main crates: +implementation is done using two main crates: - `stable_mir`: Public crate, to be published on crates.io, which will contain -the stable data structure as well as proxy APIs to make calls to the -compiler. -- `rustc_smir`: The compiler crate that will translate from internal MIR to -SMIR. This crate will also implement APIs that will be invoked by -stable-mir to query the compiler for more information. +the stable data structure as well as calls to `rustc_smir` APIs and +translation between stable and internal constructs. +- `rustc_smir`: This crate implements the public APIs to the compiler. +It is responsible for gathering all the information requested, and providing +the data in its unstable form. -This will help tools to communicate with the rust compiler via stable APIs. Tools will depend on -`stable_mir` crate, which will invoke the compiler using APIs defined in `rustc_smir`. I.e.: +I.e., +tools will depend on `stable_mir` crate, +which will invoke the compiler using APIs defined in `rustc_smir`. + +I.e.: ``` ┌──────────────────────────────────┐ ┌──────────────────────────────────┐ @@ -104,9 +36,3 @@ This will help tools to communicate with the rust compiler via stable APIs. Tool More details can be found here: https://hackmd.io/XhnYHKKuR6-LChhobvlT-g?view - -For now, the code for these two crates are in separate modules of this crate. -The modules have the same name for simplicity. We also have a third module, -`rustc_internal` which will expose APIs and definitions that allow users to -gather information from internal MIR constructs that haven't been exposed in -the `stable_mir` module.