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MIR move elimination [5/6]: Storage reconstruction - #163339

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Amanieu:move-elimination/storage-reconstruction
Nov 1, 2026
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MIR move elimination [5/6]: Storage reconstruction#163339
rust-bors[bot] merged 2 commits into
rust-lang:mainfrom
Amanieu:move-elimination/storage-reconstruction

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@Amanieu

@Amanieu Amanieu commented Sep 25, 2026 •
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Depends on #163338

This PR extends the MoveElimination pass from rust-lang/rfcs#3943 to reconstruct StorageLive/StorageDead statements for all locals by using the liveness information collected by PreciseLiveness.

r? tmiasko

@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-clippy Relevant to the Clippy team. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Sep 25, 2026
@Amanieu

Amanieu commented Sep 25, 2026 •
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LLM disclosure: LLMs were used to generate the boilerplate for the MIR tests, but each test was manually reviewed and adjusted before committing. LLMs were also used to audit this pass against the rest of the compiler MIR transforms and Miri semantics.

@Amanieu Amanieu added the llm-assisted An LLM-assisted PR as defined by the LLM policy. Requires ahead-of-time consent by assignee. label Sep 25, 2026
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 6745385 to 96e6975 Compare September 26, 2026 01:05
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 96e6975 to 7736978 Compare September 30, 2026 12:49
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 7736978 to eab2d36 Compare September 30, 2026 13:03
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from eab2d36 to 53be078 Compare October 8, 2026 23:26
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 53be078 to 579316a Compare October 9, 2026 11:11
@rustbot rustbot added the A-attributes Area: Attributes (`#[…]`, `#![…]`) label Oct 9, 2026
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 579316a to 6256aaa Compare October 10, 2026 17:58
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 4d906d5 to 07bdf02 Compare October 19, 2026 20:54
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 07bdf02 to 74b0f10 Compare October 20, 2026 07:53
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from 74b0f10 to 3f8e6da Compare October 21, 2026 15:32
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Amanieu marked this pull request as ready for review October 21, 2026 15:32
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Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 21, 2026
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dianqk commented Oct 22, 2026

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I think this is a bit similar to #142531. I don't actually see any mir-opt pass that uses storage's UB in the real world. Should we have a dedicated StorageReconstruction pass placed later in the pipeline?
When using a local at a new location, we just remove the storage marks. StorageReconstruction will bring them back.
I think this should benefit other passes, such as Inline.

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 28, 2026
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tmiasko commented Oct 29, 2026

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@bors r+

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📌 Commit fd0bab6 has been approved by tmiasko

It is now in the queue for this repository.

@rust-bors rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 29, 2026
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Amanieu force-pushed the move-elimination/storage-reconstruction branch from fd0bab6 to 0827b4d Compare October 29, 2026 20:24
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⚠️ A new commit 0827b4d71504bc9844a2c8c6dd2af4816857e6c4 was pushed.

This pull request was unapproved.

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Amanieu commented Oct 29, 2026

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Collapsed the commits

@bors r= tmiasko

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Unknown value for argument "r". Run @bors help or go to https://bors.rust-lang.org/help to see available commands.

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@bors r=tmiasko

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📌 Commit 0827b4d has been tentatively approved by tmiasko

It will be put into the queue for this repository once PR CI succeeds.

@rust-bors rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 29, 2026
@JonathanBrouwer

JonathanBrouwer commented Oct 30, 2026

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@bors rollup=iffy
Making a rollup of perf sensitive prs

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Oct 30, 2026
@JonathanBrouwer
Rollup merge of rust-lang#163339 - Amanieu:move-elimination/storage-r…
e8f3f5e 
…econstruction, r=tmiasko

MIR move elimination [5/6]: Storage reconstruction

Depends on rust-lang#163338

This PR extends the `MoveElimination` pass from rust-lang/rfcs#3943 to reconstruct `StorageLive`/`StorageDead` statements for all locals by using the liveness information collected by `PreciseLiveness`.

r? tmiasko
@JonathanBrouwer JonathanBrouwer mentioned this pull request Oct 30, 2026
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@Amanieu

Amanieu commented Oct 30, 2026

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This one has no perf impact, the optimization is disabled by default.

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JonathanBrouwer commented Oct 30, 2026

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Ah I see, thanks!
Well it's in the perf rollup now so I'll just let it be :)

rust-bors Bot pushed a commit that referenced this pull request Oct 30, 2026
@bors
Auto merge of #165205 - JonathanBrouwer:rollup-mjatgnE, r=JonathanBro…
6a78c37 
…uwer

Rollup of 7 perf-sensitive pull requests

Successful merges:

 - #163339 (MIR move elimination [5/6]: Storage reconstruction)
 - #163525 (Move lang item collection to the resolver)
 - #163928 (do not prefer trivially true candidates with `-Znext-solver` )
 - #164341 (Expand an early return case in `coerce_unsized`)
 - #164484 (Use adaptive sparse encoding for metadata tables)
 - #164607 (destringlyfy lint infrastructure)
 - #165160 (New solver opts for diesel (part 3))

> [!WARNING]
> This rollup conflicts with pending auto build #165178 and may need to be recreated if the pending build succeeds.
rust-bors Bot pushed a commit that referenced this pull request Oct 31, 2026
@bors
Auto merge of #165205 - JonathanBrouwer:rollup-mjatgnE, r=JonathanBro…
62b4d9e 
…uwer

Rollup of 7 perf-sensitive pull requests

Successful merges:

 - #163339 (MIR move elimination [5/6]: Storage reconstruction)
 - #163525 (Move lang item collection to the resolver)
 - #163928 (do not prefer trivially true candidates with `-Znext-solver` )
 - #164341 (Expand an early return case in `coerce_unsized`)
 - #164484 (Use adaptive sparse encoding for metadata tables)
 - #164607 (destringlyfy lint infrastructure)
 - #165160 (New solver opts for diesel (part 3))

> [!WARNING]
> This rollup conflicts with pending auto build #165178 and may need to be recreated if the pending build succeeds.
rust-bors Bot pushed a commit that referenced this pull request Oct 31, 2026
@bors
Auto merge of #165205 - JonathanBrouwer:rollup-mjatgnE, r=JonathanBro…
263868e 
…uwer

Rollup of 7 perf-sensitive pull requests

Successful merges:

 - #163339 (MIR move elimination [5/6]: Storage reconstruction)
 - #163525 (Move lang item collection to the resolver)
 - #163928 (do not prefer trivially true candidates with `-Znext-solver` )
 - #164341 (Expand an early return case in `coerce_unsized`)
 - #164484 (Use adaptive sparse encoding for metadata tables)
 - #164607 (destringlyfy lint infrastructure)
 - #165160 (New solver opts for diesel (part 3))

> [!WARNING]
> This rollup conflicts with pending auto build #165178 and may need to be recreated if the pending build succeeds.
@JonathanBrouwer JonathanBrouwer mentioned this pull request Oct 31, 2026
Merged
rust-bors Bot pushed a commit that referenced this pull request Oct 31, 2026
@bors
Auto merge of #165244 - JonathanBrouwer:rollup-qKlclC9, r=JonathanBro…
6fdaa71 
…uwer

Rollup of 7 perf-sensitive pull requests

Successful merges:

 - #163339 (MIR move elimination [5/6]: Storage reconstruction)
 - #163359 (MIR move elimination [1.5/6]: Ensure ZSTs are always initialized)
 - #163525 (Move lang item collection to the resolver)
 - #163928 (do not prefer trivially true candidates with `-Znext-solver` )
 - #164341 (Expand an early return case in `coerce_unsized`)
 - #164484 (Use adaptive sparse encoding for metadata tables)
 - #164607 (destringlyfy lint infrastructure)
@rust-bors
rust-bors Bot merged commit 6a099dc into rust-lang:main Nov 1, 2026
14 checks passed
@rustbot rustbot added this to the 1.101.0 milestone Nov 1, 2026
rust-bors Bot pushed a commit that referenced this pull request Nov 1, 2026
@bors
Unrolled build for #163339 in rollup 165244
81111e9 
Rollup merge of #163339 - Amanieu:move-elimination/storage-reconstruction, r=tmiasko

MIR move elimination [5/6]: Storage reconstruction

Depends on #163338

This PR extends the `MoveElimination` pass from rust-lang/rfcs#3943 to reconstruct `StorageLive`/`StorageDead` statements for all locals by using the liveness information collected by `PreciseLiveness`.

r? tmiasko
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