Replace query erase_and_anonymize_regions_ty with a helper function

[Zalathar]

The comments for this query suggest that it shouldn't call any other queries, and is a pure function of its input that only uses the query system for caching its return value.

If that's accurate, then we should be able to replace the query with a plain function that does its own caching.

[Zalathar]

@bors try @rust-timer queue

[rust-bors]

☔ The latest upstream changes (presumably #153846) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-bors]

☀️ Try build successful (CI)
Build commit: bc5cc60 (bc5cc606b9d8c5b37deaf2f3fbdb3d382521390d, parent: a0e206b5665d7c075cdc0ca5f3637a697e8ff55a)

[rust-timer]

Finished benchmarking commit (bc5cc60): comparison URL.

Overall result: ❌✅ regressions and improvements - 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)	0.0%	[0.0%, 0.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -2.4%, secondary 0.5%)

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)	1.0%	[0.9%, 1.1%]	2
Improvements ✅ (primary)	-2.4%	[-2.4%, -2.4%]	1
Improvements ✅ (secondary)	-0.7%	[-0.7%, -0.7%]	1
All ❌✅ (primary)	-2.4%	[-2.4%, -2.4%]	1

Cycles

Results (primary -2.2%, secondary -4.6%)

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)	-2.2%	[-2.2%, -2.2%]	1
Improvements ✅ (secondary)	-4.6%	[-4.6%, -4.6%]	1
All ❌✅ (primary)	-2.2%	[-2.2%, -2.2%]	1

Binary size

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

Bootstrap: 481.291s -> 480.666s (-0.13%)
Artifact size: 394.91 MiB -> 394.79 MiB (-0.03%)

[Zoxc]

Same as #139240

[Zalathar]

Heh, maybe I should put a note in the source warning that this has been tried multiple times.

And yeah, if this doesn’t bring a meaningful perf improvement or a meaningful simplification, then it’s hard to justify doing something custom instead of just using the query machinery.