Remove `will_cache_on_disk_for_key_fn` by zetanumbers · Pull Request #154591 · rust-lang/rust

zetanumbers · 2026-03-30T13:46:27Z

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Refactors QueryVtables and removes will_cache_on_disk_for_key_fn as unnecessary indirection.

Based and blocked on #154576.

Expecting perf improvements.

lqd · 2026-03-30T19:34:28Z

@bors try @rust-timer queue

…<try> Remove `will_cache_on_disk_for_key_fn`

rust-bors · 2026-03-30T21:43:05Z

☀️ Try build successful (CI)
Build commit: 0f75a34 (0f75a344ce44035ffe18148c5886f45b63053573, parent: cf7da0b7277cad05b79f91b60c290aa08a17a6f0)

rust-timer · 2026-03-30T22:23:24Z

Finished benchmarking commit (0f75a34): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.8%	[0.8%, 0.8%]	1
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.1%]	2
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.2%]	8
All ❌✅ (primary)	-0.1%	[-0.1%, -0.1%]	2

Max RSS (memory usage)

Results (primary 4.0%, secondary 2.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	4.0%	[4.0%, 4.0%]	1
Regressions ❌ (secondary)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	4.0%	[4.0%, 4.0%]	1

Cycles

Results (primary 2.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.0%	[2.0%, 2.0%]	1

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 483.836s -> 484.325s (0.10%)
Artifact size: 394.90 MiB -> 394.81 MiB (-0.02%)

Zalathar · 2026-03-30T23:55:01Z

Diff between the two perf runs: https://perf.rust-lang.org/compare.html?start=5a1a969187f4afe604cb916bc5740a09c5062f4b&end=0f75a344ce44035ffe18148c5886f45b63053573&stat=instructions%3Au

All of the “significicant” results look like they could be noise, unfortunately.

zetanumbers · 2026-03-31T11:25:07Z

Diff between the two perf runs: https://perf.rust-lang.org/compare.html?start=5a1a969187f4afe604cb916bc5740a09c5062f4b&end=0f75a344ce44035ffe18148c5886f45b63053573&stat=instructions%3Au
All of the “significicant” results look like they could be noise, unfortunately.

Why would you think that? Every ctfe-stress-5 full build benchmark seems to improve besides the doc profile because its weird I guess. While every other ctfe-stress-5 benchmark (i.e. incremental unchanged and that doc build) didn't really regressed either.

https://perf.rust-lang.org/compare.html?start=5a1a969187f4afe604cb916bc5740a09c5062f4b&end=0f75a344ce44035ffe18148c5886f45b63053573&stat=instructions%3Au&nonRelevant=true&name=ctfe-stress-5

zetanumbers · 2026-03-31T11:27:57Z

Either way this is also a refactor PR.

rustbot · 2026-04-01T10:23:57Z

r? @jieyouxu

rustbot has assigned @jieyouxu.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler, query-system
compiler, query-system expanded to 69 candidates
Random selection from 12 candidates

Zalathar · 2026-04-01T11:32:09Z

I don’t quite understand the motivation behind this as a cleanup.

It removes a function pointer from the vtable, but replaces it with two booleans in the vtable, which doesn’t strike me as an improvement over the current code.

Is there some reason to prefer the approach in this PR?

jieyouxu · 2026-04-01T11:37:20Z

r? Zalathar (since you're already looking at it)

rustbot · 2026-04-01T11:37:26Z

Zalathar is not on the review rotation at the moment.
They may take a while to respond.

zetanumbers · 2026-04-01T11:49:28Z

I don’t quite understand the motivation behind this as a cleanup.
It removes a function pointer from the vtable, but replaces it with two booleans in the vtable, which doesn’t strike me as an improvement over the current code.
Is there some reason to prefer the approach in this PR?

Pair of bools is smaller than one function pointer. Removes some dynamic dispatch. Less lines of code overall.

cjgillot

r=me with a nit

View changes since this review

rustbot · 2026-05-26T08:43:28Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

zetanumbers · 2026-05-26T09:05:00Z

Since #155080 have been merged this PR might now have a more significant impact on perf.

cjgillot · 2026-05-29T20:38:47Z

@bors try @rust-timer queue

…<try> Remove `will_cache_on_disk_for_key_fn`

rust-bors · 2026-05-29T22:51:41Z

☀️ Try build successful (CI)
Build commit: aee8937 (aee89370c1190ed73a83e9fe0c453e894c0bbe7d, parent: 6368fd52cb9f230dfb156097625993e7a8891800)

rust-timer · 2026-05-29T23:32:17Z

Finished benchmarking commit (aee8937): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (primary 3.1%, secondary -5.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	3.1%	[3.1%, 3.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.4%	[-5.4%, -5.4%]	1
All ❌✅ (primary)	3.1%	[3.1%, 3.1%]	1

Cycles

Results (secondary 5.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.7%	[5.1%, 6.7%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 511.654s -> 509.773s (-0.37%)
Artifact size: 400.70 MiB -> 400.68 MiB (-0.01%)

cjgillot · 2026-05-30T09:31:26Z

@bors r+ rollup-

rust-bors · 2026-05-30T09:31:29Z

📌 Commit 9d82fce has been approved by cjgillot

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 1. This pull request will be tested once the tree is reopened.

…uwer Rollup of 12 pull requests Successful merges: - #154591 (Remove `will_cache_on_disk_for_key_fn`) - #156672 (Misc improvements to coroutine transform code) - #157027 (HIR ty lowering: Move some things into submodules) - #157051 (Allow two object files for a single CGU in CompiledModule) - #157100 (Some more per owner things) - #153497 (Use `trait_object_dummy_self` more & heavily fix+update related docs) - #155638 (Fix tupled closure signature in `AsyncFn` arg mismatch diagnostic) - #156826 (style: Clarify nullary call and `()` no-break rule applies past max width) - #157004 (Remove unused functions in `value_analysis.rs`) - #157032 (Fixed more &x ->&mut x suggestions) - #157033 (Note irrefutable while let in loop type errors) - #157139 (compiler: `ops::RangeInclusive` → `range::RangeInclusive`) Failed merges: - #156875 (Correct and document semantics of `yield` terminator)

Rollup merge of #154591 - zetanumbers:refactor_query_fns_and_traits, r=cjgillot Remove `will_cache_on_disk_for_key_fn` Refactors `QueryVtables` and removes `will_cache_on_disk_for_key_fn` as unnecessary indirection. Based and blocked on #154576. Expecting perf improvements.

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rust-borsBot pushed a commit that referenced this pull request Mar 30, 2026
Auto merge of#154591- zetanumbers:refactor_query_fns_and_traits, r=…
0f75a34
…<try> Remove `will_cache_on_disk_for_key_fn`

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Mar 30, 2026

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Mar 30, 2026

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zetanumbers force-pushed the refactor_query_fns_and_traits branch from 9e740ff to aa17145Compare April 1, 2026 10:22

zetanumbers marked this pull request as ready for review April 1, 2026 10:23

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 1, 2026

rustbot assigned jieyouxu Apr 1, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Apr 1, 2026

rustbot assigned Zalathar and unassigned jieyouxu Apr 1, 2026

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cjgillot reviewed May 25, 2026
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Comment threadcompiler/rustc_middle/src/query/plumbing.rs Outdated

Remove will_cache_on_disk_for_key_fn and AsLocalQueryKey
239e4dd

zetanumbers force-pushed the refactor_query_fns_and_traits branch from aa17145 to 239e4ddCompare May 26, 2026 08:43

zetanumbers added 3 commits May 26, 2026 11:50

Rename helper QueryVTable method back
76c099c

Fix and update changes
0a36812

Formatter
9d82fce

cjgillot self-assigned this May 29, 2026

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 29, 2026

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rust-borsBot pushed a commit that referenced this pull request May 29, 2026
Auto merge of#154591- zetanumbers:refactor_query_fns_and_traits, r=…
aee8937
…<try> Remove `will_cache_on_disk_for_key_fn`

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rustbot removed S-waiting-on-perf Status: Waiting on a perf run to be completed. perf-regression Performance regression. labels May 29, 2026

rust-borsBot 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 May 30, 2026

JonathanBrouwer mentioned this pull request May 30, 2026
Rollup of 12 pull requests #157149
Merged

rust-borsBot merged commit e8659d7 into rust-lang:mainMay 30, 2026
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rustbot added this to the 1.98.0 milestone May 30, 2026

zetanumbers deleted the refactor_query_fns_and_traits branch June 1, 2026 08:36

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rust-timer commented Mar 30, 2026

Overall result: ❌✅ regressions and improvements - please read the text below

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Overall result: no relevant changes - no action needed

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