Start using pattern types in libcore #136006

oli-obk · 2025-01-24T16:24:51Z

Replaces the innards of NonNull with *const T is !null.

This does affect LLVM's optimizations, as now reading the field preserves the metadata that the field is not null, and transmuting to another type (e.g. just a raw pointer), will also preserve that information for optimizations. This can cause LLVM opts to do more work, but it's not guaranteed to produce better machine code.

Once we also remove all uses of rustc_layout_scalar_range_start from rustc itself, we can remove the support for that attribute entirely and handle all such needs via pattern types

compiler-errors

Well r=me when/if it does get unblocked.

library/core/src/num/niche_types.rs

rustbot · 2025-01-27T09:38:22Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Veykril · 2025-01-27T09:54:06Z

Re rust-analyzer blocker, as it turns out to implement pattern types (to a degree that would unblock this) it comes down to the same architecture changes required as for rust-lang/rust-analyzer#7434 (which I am currently looking into), so that will take a bit.

rustbot · 2025-01-27T15:53:28Z

Some changes occurred to the CTFE machinery

cc @rust-lang/wg-const-eval

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

compiler/rustc_const_eval/src/interpret/validity.rs

bors · 2025-11-17T11:23:17Z

☔ The latest upstream changes (presumably #149013) made this pull request unmergeable. Please resolve the merge conflicts.

…BoxyUwU Add NonNull pattern types These are the final piece missing for * rust-lang#136006 We cannot use the previous scheme of using an integer range for raw pointers, as we're not just changing the layout of raw pointers anymore, but also the type representation. And we can't represent "any provenance or NonZero<usize>" natively as patterns. So I created a new `!null` pattern. Since this is all unstable representation stuff for replacing rustc_layout_scalar_range_start with pattern types, the divergence from normal patterns is fine, especially since T-lang seems interested in exploring general negation patterns r? `@BoxyUwU`

Add proper name mangling for pattern types requires adding demangler support first rust-lang/rustc-demangle#81 needed for rust-lang/rust#136006 (comment) as otherwise we will have symbol collisions

Add NonNull pattern types These are the final piece missing for * rust-lang/rust#136006 We cannot use the previous scheme of using an integer range for raw pointers, as we're not just changing the layout of raw pointers anymore, but also the type representation. And we can't represent "any provenance or NonZero<usize>" natively as patterns. So I created a new `!null` pattern. Since this is all unstable representation stuff for replacing rustc_layout_scalar_range_start with pattern types, the divergence from normal patterns is fine, especially since T-lang seems interested in exploring general negation patterns r? `@BoxyUwU`

Start using pattern types in libcore (NonZero and friends) part of #136006 This PR only changes the internal representation of `NonZero`, `NonMax`, ... and other integral range types in libcore. This subsequently affects other types made up of it, but nothing really changes except that the field of `NonZero` is now accessible safely in contrast to the `rustc_layout_scalar_range_start` attribute, which has all kinds of obscure rules on how to properly access its field.

Start using pattern types in libcore (NonZero and friends) part of rust-lang/rust#136006 This PR only changes the internal representation of `NonZero`, `NonMax`, ... and other integral range types in libcore. This subsequently affects other types made up of it, but nothing really changes except that the field of `NonZero` is now accessible safely in contrast to the `rustc_layout_scalar_range_start` attribute, which has all kinds of obscure rules on how to properly access its field.

rustbot · 2026-02-13T10:22:21Z

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.

oli-obk · 2026-02-13T10:22:27Z

@bors try @rust-timer queue

Start using pattern types in libcore

Use `!null` pattern type in libcore

rust-bors · 2026-02-13T12:35:23Z

☀️ Try build successful (CI)
Build commit: 224f039 (224f0390307c2a60250e46665674e8530fa32631, parent: 47611e16044c68ef27bac31c35fda2ba1dc20b73)

rust-timer · 2026-02-13T13:45:20Z

Finished benchmarking commit (224f039): 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)	0.2%	[0.2%, 0.2%]	1
Regressions ❌ (secondary)	0.5%	[0.0%, 1.8%]	8
Improvements ✅ (primary)	-0.8%	[-3.2%, -0.2%]	20
Improvements ✅ (secondary)	-1.1%	[-1.8%, -0.1%]	5
All ❌✅ (primary)	-0.7%	[-3.2%, 0.2%]	21

Max RSS (memory usage)

Results (primary 2.5%, secondary -2.6%)

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

	mean	range	count
Regressions ❌ (primary)	3.9%	[2.4%, 5.7%]	4
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-2.6%	[-3.4%, -1.7%]	2
All ❌✅ (primary)	2.5%	[-2.9%, 5.7%]	5

Cycles

Results (primary -2.5%, secondary -0.0%)

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)	4.2%	[2.4%, 8.3%]	4
Improvements ✅ (primary)	-2.5%	[-2.5%, -2.5%]	1
Improvements ✅ (secondary)	-2.9%	[-5.5%, -2.1%]	6
All ❌✅ (primary)	-2.5%	[-2.5%, -2.5%]	1

Binary size

Results (primary -0.1%, secondary 0.2%)

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

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.0%, 0.9%]	9
Regressions ❌ (secondary)	1.0%	[0.0%, 5.3%]	7
Improvements ✅ (primary)	-0.2%	[-1.1%, -0.0%]	26
Improvements ✅ (secondary)	-0.1%	[-0.9%, -0.0%]	22
All ❌✅ (primary)	-0.1%	[-1.1%, 0.9%]	35

Bootstrap: 482.691s -> 481.225s (-0.30%)
Artifact size: 398.13 MiB -> 396.21 MiB (-0.48%)

rustbot assigned ibraheemdev Jan 24, 2025

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rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jan 24, 2025

oli-obk added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 24, 2025

oli-obk unassigned ibraheemdev Jan 24, 2025