Stable Hash: Ignore all HirIds that just identify the node itself

[oli-obk]

This should provide better incremental caching, but it seems there is more to it.

These IDs also serve no purpose being in the stable hash of the item they refer to, only when referring to another item is it important that we hash the HirId. So we can at least avoid the cost during stable hashing, even if we don't benefit from it by avoiding some queries' caches from being invalidated

Unsure how to make sure we do this right by construction. Would be nice to do something type based

[rustbot]

r? @petrochenkov

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[oli-obk]

@bors try @rust-timer queue

[bors]

⌛ Trying commit ad7bb20 with merge f0fb86e...

[bors]

☀️ Try build successful - checks-actions
Build commit: f0fb86e (f0fb86e6d75f7775a227ea2728a902286d87427a)

[rust-timer]

Finished benchmarking commit (f0fb86e): comparison URL.

Overall result: ✅ 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 the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-1.0%, -0.1%]	175
Improvements ✅ (secondary)	-0.5%	[-1.3%, -0.1%]	87
All ❌✅ (primary)	-0.4%	[-1.0%, -0.1%]	175

Max RSS (memory usage)

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

Cycles

Results (primary -1.4%, secondary -6.2%)

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)	2.4%	[2.4%, 2.4%]	1
Improvements ✅ (primary)	-1.4%	[-1.4%, -1.4%]	1
Improvements ✅ (secondary)	-7.6%	[-8.8%, -6.7%]	6
All ❌✅ (primary)	-1.4%	[-1.4%, -1.4%]	1

Binary size

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

Bootstrap: 763.376s -> 765.068s (0.22%)
Artifact size: 325.75 MiB -> 325.77 MiB (0.01%)

[oli-obk]

Hmm sad, no changes in query executions, meaning I didn't improve caching but just avoided the unnecessary hashing. Oh well, a win is a win, I'll investigate further

[oli-obk]

r? compiler

[Noratrieb]

@bors r+

[bors]

📌 Commit ad7bb20 has been approved by Noratrieb

It is now in the queue for this repository.

[bors]

⌛ Testing commit ad7bb20 with merge 6067b36...

[bors]

☀️ Test successful - checks-actions
Approved by: Noratrieb
Pushing 6067b36 to master...

[rust-timer]

Finished benchmarking commit (6067b36): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-0.9%, -0.1%]	169
Improvements ✅ (secondary)	-0.5%	[-1.3%, -0.1%]	85
All ❌✅ (primary)	-0.4%	[-0.9%, -0.1%]	169

Max RSS (memory usage)

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

Cycles

Results (primary -0.8%, secondary -3.4%)

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)	-0.8%	[-0.8%, -0.8%]	1
Improvements ✅ (secondary)	-3.4%	[-3.7%, -2.8%]	3
All ❌✅ (primary)	-0.8%	[-0.8%, -0.8%]	1

Binary size

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

Bootstrap: 763.784s -> 763.854s (0.01%)
Artifact size: 326.10 MiB -> 326.09 MiB (-0.00%)