macro_rules: Add an expansion-local cache to span marker

[petrochenkov]

Most tokens in a macro body typically have the same syntax context.
So the cache should usually be hit.

This change can either be combined with #119689, or serve as its alternative, depending on perf results.

[rustbot]

r? @compiler-errors

(rustbot has picked a reviewer for you, use r? to override)

[petrochenkov]

@bors try @rust-timer queue

[bors]

⌛ Trying commit e1c08d6 with merge 44345bd...

[bors]

☀️ Try build successful - checks-actions
Build commit: 44345bd (44345bd55c7e750b6d039208576d3e2db2ea9d9e)

[rust-timer]

Finished benchmarking commit (44345bd): 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 a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	3.1%	[3.1%, 3.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.7%	[-2.5%, -0.2%]	69
Improvements ✅ (secondary)	-0.8%	[-1.9%, -0.3%]	13
All ❌✅ (primary)	-0.7%	[-2.5%, 3.1%]	70

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)	3.6%	[2.0%, 5.6%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.3%	[-3.3%, -3.2%]	2
All ❌✅ (primary)	-	-	0

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)	2.9%	[2.9%, 2.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.9%	[2.9%, 2.9%]	1

Binary size

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

Bootstrap: 665.728s -> 666.41s (0.10%)
Artifact size: 308.41 MiB -> 308.39 MiB (-0.01%)

[cjgillot]

r=me with an in-code comment explaining why we need the local cache.

[petrochenkov]

@bors r=cjgillot

[bors]

📌 Commit edec91d has been approved by cjgillot

It is now in the queue for this repository.

[bors]

⌛ Testing commit edec91d with merge 0ee9cfd...

[bors]

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 0ee9cfd to master...

[rust-timer]

Finished benchmarking commit (0ee9cfd): comparison URL.

Overall result: ✅ 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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.4%	[-20.5%, -0.2%]	80
Improvements ✅ (secondary)	-0.8%	[-1.9%, -0.3%]	16
All ❌✅ (primary)	-1.4%	[-20.5%, -0.2%]	80

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)	2.6%	[1.2%, 4.5%]	4
Improvements ✅ (primary)	-4.9%	[-5.6%, -4.1%]	3
Improvements ✅ (secondary)	-5.3%	[-9.6%, -1.1%]	2
All ❌✅ (primary)	-4.9%	[-5.6%, -4.1%]	3

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)	-12.8%	[-18.8%, -2.9%]	4
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-12.8%	[-18.8%, -2.9%]	4

Binary size

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

Bootstrap: 666.019s -> 667.831s (0.27%)
Artifact size: 308.38 MiB -> 308.39 MiB (0.00%)

[Kobzol]

The bit bitmaps win is a reverse of a blip from #119722 (comment).