T-compiler Meeting Agenda 2025-01-02

Announcements

“regression: ICE: tcx.extern_crate(LocalCrate) is not supported for this key” rust#134705
- Regression found in latest beta crater run, solved by #133585 (beta-backport approved)

triage logs for 2024-12-30

A pretty quiet week, with the exception of a significant improvement due to landing LTO for C / C++ programs compiled as part of the build.

Triage done by @simulacrum. Revision range: 0eca4dd3..93722f7e

Summary:

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	-	-	0
Improvements (primary)	-0.6%	[-5.6%, -0.2%]	265
Improvements (secondary)	-0.7%	[-1.8%, -0.2%]	187
All (primary)	-0.6%	[-5.6%, -0.2%]	265

0 Regressions, 1 Improvements, 1 Mixed; 0 of them in rollups 53 artifact comparisons made in total

No meaningful regressions this week.

CI: Add LTO support to clang in dist-x86_64-linux #134690 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	-	-	0
Regressions (secondary)	-	-	0
Improvements (primary)	-0.7%	[-5.5%, -0.3%]	275
Improvements (secondary)	-0.9%	[-2.6%, -0.2%]	235
All (primary)	-0.7%	[-5.5%, -0.3%]	275

Consider empty-unreachable otherwise branches in MatchBranchSimplification #131244 (Comparison Link)

(instructions:u)	mean	range	count
Regressions (primary)	0.2%	[0.2%, 0.2%]	1
Regressions (secondary)	0.3%	[0.2%, 0.3%]	4
Improvements (primary)	-0.6%	[-0.7%, -0.5%]	2
Improvements (secondary)	-0.2%	[-0.3%, -0.1%]	2
All (primary)	-0.3%	[-0.7%, 0.2%]	3

“Built-in attributes are treated differently vs prelude attributes, unstable built-in attributes can name-collide with stable macro, and built-in attributes can break back-compat” rust#134963
- Nominated by @Jieyou Xu, suggests not requiring immediate attention, can be postponed to next week

Next meetings’ agenda draft: hackmd link