rustc_codegen_ssa: Buffer file writes in link_rlib

[osiewicz]

This makes this step take ~25ms on my machine (M3 Max 64GB) for Zed repo instead of ~150ms (on editor crate). Additionally it takes down the time needed for a clean cargo build of ripgrep from ~6.1s to 5.9s.

This change is mostly relevant for dev builds of crates with multiple large CGUs.
I imagine it could be quite relevant for dev scenarios on Windows, but sadly I have no way to measure that myself.

[rustbot]

r? @estebank

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[clubby789]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 563920c with merge 943e472...

[bors]

☀️ Try build successful - checks-actions
Build commit: 943e472 (943e4725c2aa4a9b784736253372f8b6fec3f1e4)

[rust-timer]

Finished benchmarking commit (943e472): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

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

Instruction count

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

Max RSS (memory usage)

Results (primary -2.3%, secondary 0.2%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.6%	[1.6%, 1.6%]	1
Improvements ✅ (primary)	-2.3%	[-2.5%, -2.2%]	2
Improvements ✅ (secondary)	-1.2%	[-1.2%, -1.2%]	1
All ❌✅ (primary)	-2.3%	[-2.5%, -2.2%]	2

Cycles

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

Binary size

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

Bootstrap: 763.109s -> 762.744s (-0.05%)
Artifact size: 325.47 MiB -> 325.48 MiB (0.00%)

[bjorn3]

Makes sense. It would be nice to keep the newlines though to somewhat delineate logical sections inside this function.

[bjorn3]

r? @bjorn3

@bors r+ rollup=never

[bors]

📌 Commit 586a805 has been approved by bjorn3

It is now in the queue for this repository.

[bors]

⌛ Testing commit 586a805 with merge 84e9308...

[bors]

☀️ Test successful - checks-actions
Approved by: bjorn3
Pushing 84e9308 to master...

[rust-timer]

Finished benchmarking commit (84e9308): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (secondary 3.8%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.8%	[2.3%, 5.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 2.8%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.8%	[2.3%, 3.3%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 760.358s -> 759.369s (-0.13%)
Artifact size: 325.48 MiB -> 325.57 MiB (0.03%)