[EXPERIMENT] Can we re-use layout_array here?

[scottmcm]

r? ghost

[scottmcm]

@bors try @rust-timer queue

[rust-log-analyzer]

The job tidy failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[TIMING:end] tool::ToolBuild { build_compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, tool: "tidy", path: "src/tools/tidy", mode: ToolBootstrap, source_type: InTree, extra_features: [], allow_features: "", cargo_args: [], artifact_kind: Binary } -- 9.560
[TIMING:end] tool::Tidy { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu } -- 0.000
fmt check
Diff in /checkout/library/alloc/src/raw_vec/mod.rs:526:
             let layout = layout_array(self.cap.as_inner(), elem_layout);
             // SAFETY: this memory has already been allocated so we know it can't overflow.
             // Use the checked-then-unchecked to communicate the length restriction to the optimizer.
-            unsafe {
-                Some((self.ptr.into(), layout.unwrap_unchecked()))
-            }
+            unsafe { Some((self.ptr.into(), layout.unwrap_unchecked())) }
         }

[rust-bors]

☀️ Try build successful (CI)
Build commit: 4ddc7cf (4ddc7cfd9365a691c613cd910d96c2e5595a9096, parent: 683dd08db5808c41baceef49368fc82a6c4767bb)

[rust-timer]

Finished benchmarking commit (4ddc7cf): 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)	0.6%	[0.4%, 0.8%]	9
Regressions ❌ (secondary)	2.0%	[0.3%, 8.8%]	8
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.1%]	3
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.1%]	13
All ❌✅ (primary)	0.4%	[-0.2%, 0.8%]	12

Max RSS (memory usage)

Results (primary 5.4%, secondary 1.5%)

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

	mean	range	count
Regressions ❌ (primary)	5.4%	[5.4%, 5.4%]	1
Regressions ❌ (secondary)	3.7%	[2.7%, 4.8%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.6%	[-2.3%, -0.7%]	3
All ❌✅ (primary)	5.4%	[5.4%, 5.4%]	1

Cycles

Results (secondary 2.1%)

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)	4.1%	[2.5%, 9.9%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.5%	[-2.8%, -2.2%]	3
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.2%, 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)	0.2%	[0.0%, 0.7%]	12
Regressions ❌ (secondary)	0.1%	[0.0%, 0.1%]	2
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.0%]	2
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	19
All ❌✅ (primary)	0.2%	[-0.1%, 0.7%]	14

Bootstrap: 470.773s -> 473.478s (0.57%)
Artifact size: 388.83 MiB -> 389.05 MiB (0.06%)