Move CacheDecoder to rustc_query_impl

[Zoxc]

This moves CacheDecoder back to rustc_query_impl in a new cache_decoder module.

A perf run could a be good idea.

r? @cjgillot

[cjgillot]

I'm not convinced by this PR. In general, it's preferable to keep Encodable and Decodable impls close together, as they need to evolve in close sync. In addition, we lose a lot of encapsulation in the cache, which is very unfortunate.

@bors try @rust-timer queue

[bors]

⌛ Trying commit 23e02152bb775a40ad5b203ac824e97590bf4342 with merge 087b665f9fbafa28735d2ac37ab29bc6d2cf323b...

[bors]

☀️ Try build successful - checks-actions
Build commit: 087b665f9fbafa28735d2ac37ab29bc6d2cf323b (087b665f9fbafa28735d2ac37ab29bc6d2cf323b)

[rust-timer]

Finished benchmarking commit (087b665f9fbafa28735d2ac37ab29bc6d2cf323b): comparison URL.

Overall result: ❌ regressions - 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)	0.2%	[0.2%, 0.2%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[0.2%, 0.2%]	1

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)	3.2%	[3.2%, 3.2%]	1
Improvements ✅ (primary)	-4.3%	[-4.3%, -4.3%]	1
Improvements ✅ (secondary)	-2.2%	[-2.2%, -2.2%]	1
All ❌✅ (primary)	-4.3%	[-4.3%, -4.3%]	1

Cycles

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.5%	[-4.9%, -4.2%]	4
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 643.403s -> 642.925s (-0.07%)

[Zoxc]

on_disk_cache.rs is large enough to warrant splitting into modules. I also intend to move CacheEncoder to a new module next to it. The loss of encapsulation is unfortunate, but that happens quite a bit in rustc since it's split into many crates. I do prefer that loss over use of unsafe code to keep it in rustc_query_impl however.

Another possible configuration would be to move CacheDecoder and CacheEncoder to rustc_query_system with the impls being next to the types, but that splits the impls up further. Keeping them in rustc_middle isn't a great option if we want to allow other crates to define queries.

[bors]

☔ The latest upstream changes (presumably #112877) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #112938) made this pull request unmergeable. Please resolve the merge conflicts.

[JohnCSimon]

@Zoxc
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.

[tranquillity-codes]

Closing this due to no activity. Feel free to open a new pr or reopen this