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Zero-Sized Types Actually Exist in MIR

• Series: Rust (mir) compiler bites
• Channel: Regional Tantrums
• Demo repo: zst-in-mir-demo (this repo — cargo rustc -- -Zunpretty=mir)

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Intro

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Promoted Constants in Rust MIR

This document explains how Rust handles promoted constants, why they exist.

Table of Contents

1. What Are Promoted Constants?
2. MIR Syntax
3. Memory Layout
4. Code References

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Your for Loop Is a Lie: How Rust Desugars Iterators in MIR

Table of Contents

1. The Code
2. Dumping the MIR
3. The Desugaring Chain
4. Anatomy of the MIR
5. What Iterator::next() Does Internally
6. Checked Arithmetic: Why sum += i Returns a Tuple

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Closures Are Just Structs: MIR's Closure Desugaring

When you write |x| x + factor, Rust creates an anonymous struct, implements a trait on it, and calls a method.

Table of Contents

1. The Code
2. Dumping the MIR
3. The Desugaring Chain

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stable-mir

For a video version of this — https://www.youtube.com/watch?v=lfi2pCOaGGk&t=927s

Disclaimer

MIR - Rust’s mid-level IR

• Simplified, control-flow-oriented representation.

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./x build
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.07s
$ cargo +nightly-aarch64-apple-darwin build --manifest-path /Users/nihalpasham/devspace/rust/compiler/rustc_public/rustc_public/Cargo.toml --all-targets
   Compiling rustc_public v0.1.0-preview (/Users/nihalpasham/devspace/rust/compiler/rustc_public/rustc_public)
error[E0412]: cannot find type `DynKind` in module `rustc_ty`
   --> rustc_public/src/unstable/convert/internal.rs:464:30
    |
464 |     type T<'tcx> = rustc_ty::DynKind;
    |                              ^^^^^^^

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GP-GPU Programming Ramblings

#nvidia #cuda #gpu #arch #metal #rocm #triton

• Tensor Cores and Tensor Memory Accelerator
• Split Barriers (Ampere and above)
• Thread Block Cluster (Hopper and above)
• Producer-Consumer Queues

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True cross-platform GPU compute —WebGPU + WGML


WebGPU vs WebGL

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High-level overview focusing on graph structure, search-based compilation, and visualization:

Luminal Architecture Overview

1. Core Graph Structure

Luminal is built around a directed acyclic graph (DAG) representation where:

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Cranelift

#idempotent

Cranelift IR:

• Functions are compiled individually
• The instructions in the function body use and produce values in SSA form i.e. Single Static Assignment