struct_target_features: reduce serialized rmeta

[veluca93]

Reduce the amount of serialized information in rmeta. This should fix the binary size regression in #127537 and may also fix the speed regression.

r? compiler-errors

Tracking issue: #129107

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit c38046b with merge c202448...

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 3bea594 with merge 17d65a0...

[bors]

☀️ Try build successful - checks-actions
Build commit: 17d65a0 (17d65a0422d37eedbe37cfdb1221bd711485586a)

[rust-timer]

Finished benchmarking commit (17d65a0): comparison URL.

Overall result: ❌✅ regressions and improvements - 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 is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.2%	[3.2%, 3.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-6.4%	[-6.4%, -6.4%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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

Cycles

Results (secondary -5.2%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.2%	[-5.2%, -5.2%]	1
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -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)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.5%, -0.0%]	32
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-0.5%, -0.0%]	32

Bootstrap: missing data
Artifact size: 338.73 MiB -> 338.65 MiB (-0.03%)

[veluca93]

The results confuse me slightly (they seem to report only a subset of the results that showed regressions in the previous PR?), but it seems like this does indeed fix the binary size regression introduced in #127537, at least for those crates that results were reported about.

Will look at the instruction count regression next (in a separate PR ;-))

[compiler-errors]

@bors r+

[bors]

📌 Commit 3bea594 has been approved by compiler-errors

It is now in the queue for this repository.

[Kobzol]

@bors r-

We think that the original PR might have introduced perf. instability, so we might have to revert it (#129854). Let's not add additional stuff on top of it until we resolve the perf. results instability (the perf. result reported above is incomplete anyway, due to our current perf. collector problems).

[bors]

☔ The latest upstream changes (presumably #129854) made this pull request unmergeable. Please resolve the merge conflicts.