Encode shorthands for spans in metadata.

[cjgillot]

Spans occupy a typically large proportion of metadata.
This PR deduplicates encoded spans in order to reduce encoded length.

[cjgillot]

@bors try @rust-timer queue

[bors]

⌛ Trying commit d73fdaacd72b82107467b30d547496d2517ad625 with merge 3fe9b8f877a65dfbdfe4b12565d256386178bf06...

[bors]

☀️ Try build successful - checks-actions
Build commit: 3fe9b8f877a65dfbdfe4b12565d256386178bf06 (3fe9b8f877a65dfbdfe4b12565d256386178bf06)

[rust-timer]

Finished benchmarking commit (3fe9b8f877a65dfbdfe4b12565d256386178bf06): 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)	0.9%	[0.2%, 1.2%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.6%]	2
All ❌✅ (primary)	-	-	0

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)	1.7%	[0.7%, 3.7%]	53
Regressions ❌ (secondary)	2.4%	[1.1%, 4.4%]	23
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.7%	[0.7%, 3.7%]	53

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)	1.2%	[1.0%, 1.3%]	2
Regressions ❌ (secondary)	5.0%	[2.0%, 7.7%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.6%	[-6.0%, -5.4%]	3
All ❌✅ (primary)	1.2%	[1.0%, 1.3%]	2

Binary size

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)	1.4%	[1.4%, 1.4%]	6
Improvements ✅ (primary)	-2.2%	[-7.8%, -0.1%]	117
Improvements ✅ (secondary)	-3.2%	[-12.3%, -0.0%]	64
All ❌✅ (primary)	-2.2%	[-7.8%, -0.1%]	117

Bootstrap: 647.294s -> 647.078s (-0.03%)

[cjgillot]

Instruction count results are not very interesting. Meanwhile, we get up to 12% reduction of metadata size.

r? compiler

[compiler-errors]

Awesome -- straightforward impl and great to see it has such an effect on metadata.

r? @compiler-errors @bors r+

[bors]

📌 Commit 186be72 has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit 186be72 with merge fdfcdad...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing fdfcdad to master...

[rust-timer]

Finished benchmarking commit (fdfcdad): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

@rustbot label: -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)	0.3%	[0.3%, 0.3%]	1
Regressions ❌ (secondary)	0.9%	[0.3%, 1.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.6%]	2
All ❌✅ (primary)	0.3%	[0.3%, 0.3%]	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)	1.7%	[0.6%, 3.5%]	53
Regressions ❌ (secondary)	2.5%	[1.2%, 5.8%]	24
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.7%	[0.6%, 3.5%]	53

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)	3.8%	[1.0%, 7.4%]	15
Regressions ❌ (secondary)	5.9%	[2.3%, 8.6%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.3%	[-5.9%, -5.0%]	3
All ❌✅ (primary)	3.8%	[1.0%, 7.4%]	15

Binary size

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)	1.4%	[1.4%, 1.4%]	6
Improvements ✅ (primary)	-2.2%	[-7.8%, -0.1%]	117
Improvements ✅ (secondary)	-3.2%	[-12.3%, -0.0%]	64
All ❌✅ (primary)	-2.2%	[-7.8%, -0.1%]	117

Bootstrap: 647.294s -> 647.681s (0.06%)