rustc_metadata: Remove Span from ModChild

[petrochenkov]

It can be decoded on demand from regular def_span tables.

Partially mitigates perf regressions from #109500.

[rustbot]

r? @eholk

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

[petrochenkov]

@bors try @rust-timer queue

[bors]

⌛ Trying commit f886a6f216c97de7c0f76c5b178cd446f4d09d38 with merge 8d909089726b8407c014ce90cbccb7f4ce87e7d0...

[bors]

☀️ Try build successful - checks-actions
Build commit: 8d909089726b8407c014ce90cbccb7f4ce87e7d0 (8d909089726b8407c014ce90cbccb7f4ce87e7d0)

[eholk]

Since this says [WIP], I'm assuming it's not ready to be merged. I'll mark this was waiting on author in the meantime, but feel free to send it back if/when you're ready to have it reviewed.

@rustbot author

[petrochenkov]

I'm going to block this on #109500 for now.

[petrochenkov]

@bors try @rust-timer queue

[bors]

⌛ Trying commit e6fb8c06af6ea4e83b9b77795712b9aa1329d334 with merge 20dbcc2611924671c4202366c03504fe3b1e5e15...

[bors]

☀️ Try build successful - checks-actions
Build commit: 20dbcc2611924671c4202366c03504fe3b1e5e15 (20dbcc2611924671c4202366c03504fe3b1e5e15)

[bors]

📌 Commit c271d39c481e400583495a1c7ae4a182e8d1edc5 has been approved by cjgillot

It is now in the queue for this repository.

[bors]

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

1. git checkout slimchild (switch to your branch)
2. git fetch upstream master (retrieve the latest master)
3. git rebase upstream/master -p (rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self slimchild --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging compiler/rustc_metadata/src/rmeta/encoder.rs
CONFLICT (content): Merge conflict in compiler/rustc_metadata/src/rmeta/encoder.rs
Automatic merge failed; fix conflicts and then commit the result.

[bors]

☔ The latest upstream changes (presumably #110458) made this pull request unmergeable. Please resolve the merge conflicts.

[cjgillot]

@bors r+

[bors]

📌 Commit ec8f688 has been approved by cjgillot

It is now in the queue for this repository.

[bors]

⌛ Testing commit ec8f688 with merge c609da5...

[bors]

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing c609da5 to master...

[rust-timer]

Finished benchmarking commit (c609da5): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.4%	[0.3%, 0.5%]	5
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-0.4%	[-0.7%, -0.2%]	15
Improvements ✅ (secondary)	-1.4%	[-4.2%, -0.4%]	13
All ❌✅ (primary)	-0.2%	[-0.7%, 0.5%]	20

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)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	3.2%	[2.1%, 4.3%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.6%	[-2.9%, -2.1%]	6
All ❌✅ (primary)	2.6%	[2.6%, 2.6%]	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)	-2.9%	[-3.9%, -2.0%]	4
All ❌✅ (primary)	-	-	0

[nnethercote]

The perf wins greatly outweigh losses.

@rustbot label: +perf-regression-triaged