Use less catch_unwind in lang_start_internal

[joboet]

Moving abort guards to destructors can yield better codegen than catch_unwind in user code, so perhaps it also works for lang_start?

Could someone trigger rust-timer for me, please? I don't have permissions.

Using an aborting drop guard to stop unwinding is a bit cleaner and avoids the footguns associated with catch_unwind.

The impact on binary size is unfortunately negligible (-4kB on my machine for "hello world").

[rustbot]

r? @Mark-Simulacrum

(rustbot has picked a reviewer for you, use r? to override)

[Noratrieb]

I don't think rustc perf will have any useful results, the compiler is a very big program so this small one time startup change will probably not make it over the noise threshold. You're probably better off benchmarking a hello world or something like that locally.

[joboet]

I don't think rustc perf will have any useful results, the compiler is a very big program so this small one time startup change will probably not make it over the noise threshold. You're probably better off benchmarking a hello world or something like that locally.

lang_start did previously have a perf-impact (#88988), so I'm curious whether it does here as well. But sure, I'll test it locally first.

[Noratrieb]

Well, I can start one anyways, we have enough
@bors try @rust-timer queue

[bors]

⌛ Trying commit 19910f1a550a300ef0153176fdb69baacff3d0cb with merge 71e1728448334ed5b308e433eb07ff411a98b7e6...

[bors]

☀️ Try build successful - checks-actions
Build commit: 71e1728448334ed5b308e433eb07ff411a98b7e6 (71e1728448334ed5b308e433eb07ff411a98b7e6)

[rust-timer]

Finished benchmarking commit (71e1728448334ed5b308e433eb07ff411a98b7e6): 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

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)	3.5%	[2.8%, 4.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.5%	[-2.5%, -2.5%]	1
All ❌✅ (primary)	-	-	0

Cycles

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

[rustbot]

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

• Stabilizing library features
• Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
• Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
• Changing public documentation in ways that create new stability guarantees
• Changing observable runtime behavior of library APIs

[joboet]

@rustbot author
Until I figure out CI...

[JohnCSimon]

@joboet

ping from triage - can you post your status on this PR? There hasn't been an update in a few months. Thanks!

FYI: when a PR is ready for review, send a message containing
@rustbot ready to switch to S-waiting-on-review so the PR is in the reviewer's backlog.

[joboet]

This doesn't really have an impact except maybe making the code a bit more readable, so I'm not really motivated to find the issue that caused CI to fail here. I'll just close this.