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bors 000ccd651d Auto merge of #148766 - cjgillot:mir-const-runtime-checks, r=RalfJung,saethlin

Replace Rvalue::NullaryOp by a variant in mir::Operand.

Based on https://github.com/rust-lang/rust/pull/148151

This PR fully removes the MIR `Rvalue::NullaryOp`. After rust-lang/rust#148151, it was only useful for runtime checks like `ub_checks`, `contract_checks` and `overflow_checks`.

These are "runtime" checks, boolean constants that may only be `true` in codegen. It depends on a rustc flag passed to codegen, so we need to represent those flags cross-crate.

This PR replaces those runtime checks by special variants in MIR `ConstValue`. This allows code that expects constants to manipulate those as such, even if we may not always be able to evaluate them to actual scalars.

2025-12-22 06:58:28 +00:00

src

Auto merge of #148766 - cjgillot:mir-const-runtime-checks, r=RalfJung,saethlin

2025-12-22 06:58:28 +00:00

Cargo.toml

rustc_public: Make Id types !Send / !Sync

2025-11-19 19:46:18 +00:00

README.md

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rust-toolchain.toml

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README.md

This crate is currently developed in-tree together with the compiler.

Our goal is to start publishing stable_mir into crates.io. Until then, users will use this as any other rustc crate, by installing the rustup component rustc-dev, and declaring stable-mir as an external crate.

See the StableMIR "Getting Started" guide for more information.

Stable MIR Design

The stable-mir will follow a similar approach to proc-macro2. Its implementation is split between two main crates:

stable_mir: Public crate, to be published on crates.io, which will contain the stable data structure as well as calls to rustc_smir APIs. The translation between stable and internal constructs will also be done in this crate, however, this is currently implemented in the rustc_smir crate.¹.
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.

I.e., tools will depend on stable_mir crate, which will invoke the compiler using APIs defined in rustc_smir.

I.e.:

    ┌──────────────────────────────────┐           ┌──────────────────────────────────┐
    │   External Tool     ┌──────────┐ │           │ ┌──────────┐   Rust Compiler     │
    │                     │          │ │           │ │          │                     │
    │                     │stable_mir| │           │ │rustc_smir│                     │
    │                     │          │ ├──────────►| │          │                     │
    │                     │          │ │◄──────────┤ │          │                     │
    │                     │          │ │           │ │          │                     │
    │                     │          │ │           │ │          │                     │
    │                     └──────────┘ │           │ └──────────┘                     │
    └──────────────────────────────────┘           └──────────────────────────────────┘

More details can be found here: https://hackmd.io/XhnYHKKuR6-LChhobvlT-g?view

This is currently implemented in the rustc_smir crate, but we are working to change that. ↩︎