Fix performance issue in liveness checking

[chenyukang]

r? @ghost

from #150955 (comment)

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[chenyukang]

@bors try @rust-timer queue

[lqd]

Cool. r=me with green perf

View changes since this review

[rust-bors]

☀️ Try build successful (CI)
Build commit: 3a8fd6c (3a8fd6ccca553ed0605e839cc9eac17a3aa80166, parent: d940e56841ddcc05671ead99290e35ff2e98369f)

[rust-timer]

Finished benchmarking commit (3a8fd6c): comparison URL.

Overall result: ❌ regressions - no action needed

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.

@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)	0.1%	[0.1%, 0.2%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary 3.9%)

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)	3.9%	[3.9%, 3.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -2.5%)

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

Binary size

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

Bootstrap: 473.058s -> 474.35s (0.27%)
Artifact size: 383.29 MiB -> 383.32 MiB (0.01%)

[chenyukang]

@bors r=lqd

[rust-bors]

📌 Commit 54f9a44 has been approved by lqd

It is now in the queue for this repository.

[lqd]

It didn’t fix the issue you were trying to fix, right?

[chenyukang]

It didn’t fix the issue you were trying to fix, right?

seems that PR #150955 don't have that big performance regression:
#150955 (comment)

[lqd]

It doesn't indeed.

[lqd]

In any case, this new code is in a good spot now (but it's also not clear that it was causing much in the previous place) so let's land it.