Deduce captures(none) for a return place and parameters #147890

tmiasko · 2025-10-19T19:21:00Z

No description provided.

tmiasko · 2025-10-19T19:25:00Z

@bors try @rust-timer queue

deduced_param_attrs: deduce captures(none)

rust-bors · 2025-10-19T19:33:55Z

💔 Test for abbaf96 failed: CI

tmiasko · 2025-10-19T19:43:09Z

@bors try @rust-timer queue

deduced_param_attrs: deduce captures(none)

bors · 2025-10-19T21:57:27Z

☔ The latest upstream changes (presumably #147884) made this pull request unmergeable. Please resolve the merge conflicts.

rust-bors · 2025-10-19T22:04:36Z

☀️ Try build successful (CI)
Build commit: 470704e (470704e31911d010ae90e062e13a88db578f8f08, parent: c6efb9019b3169fc672248339dbbf13e6a134de3)

rust-timer · 2025-10-19T23:14:38Z

Finished benchmarking commit (470704e): 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)	0.3%	[0.1%, 1.1%]	5
Improvements ✅ (primary)	-0.3%	[-0.4%, -0.2%]	8
Improvements ✅ (secondary)	-0.4%	[-1.2%, -0.1%]	27
All ❌✅ (primary)	-0.3%	[-0.4%, -0.2%]	8

Max RSS (memory usage)

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

Cycles

Results (primary 2.8%, secondary 3.4%)

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

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	3.4%	[2.6%, 4.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.8%	[2.8%, 2.8%]	1

Binary size

Results (primary 0.0%, 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)	0.0%	[0.0%, 0.1%]	10
Regressions ❌ (secondary)	0.1%	[0.0%, 0.2%]	10
Improvements ✅ (primary)	-0.0%	[-0.0%, -0.0%]	4
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	35
All ❌✅ (primary)	0.0%	[-0.0%, 0.1%]	14

Bootstrap: 472.659s -> 472.043s (-0.13%)
Artifact size: 390.57 MiB -> 390.61 MiB (0.01%)

rustbot · 2025-10-22T17:14:55Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

tmiasko · 2025-10-22T17:17:11Z

r? compiler

compiler/rustc_middle/src/middle/deduced_param_attrs.rs

compiler/rustc_ty_utils/src/abi.rs

cjgillot · 2025-10-23T02:26:11Z

compiler/rustc_mir_transform/src/deduce_param_attrs.rs

-                    // We're only interested in arguments.
-                    && let Some(param_index) = self.as_param(place.local)
                    && !place.is_indirect_first_projection()
+                    && let Some(i) = self.as_param(place.local)


Should we also check whether that argument's type may be passed indirectly? In case of projections in particular.

I would leave further improvements for a separate pull request (although, it looks like we have an extra temporary in such a case regardless).