perf: Don't track specific live points for promoteds

[Mark-Simulacrum]

We don't query this information out of the promoted (it's basically a single "unit" regardless of the complexity within it) and this saves on re-initializing the SparseIntervalMatrix's backing IndexVec with mostly empty rows for all of the leading regions in the function. Typical promoteds will only contain a few regions that need up be uplifted, while the parent function can have thousands.

For a simple function repeating println!("Hello world"); 50,000 times this reduces compile times from 90 to 15 seconds in debug mode. The previous implementations re-initialization led to an overall roughly n^2 runtime as each promoted initialized slots for ~n regions, now we scale closer to linearly (5000 hello worlds takes 1.1 seconds).

cc #50994, #86244

[rustbot]

r? @davidtwco

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

[Mark-Simulacrum]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 5d68fa6 with merge 6c5cf74...

[bors]

☀️ Try build successful - checks-actions
Build commit: 6c5cf74 (6c5cf740e641e2fce388298e58f7f6d57b6647e9)

[rust-timer]

Finished benchmarking commit (6c5cf74): comparison URL.

Overall result: ❌ regressions - 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.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@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)	0.3%	[0.2%, 0.7%]	18
Regressions ❌ (secondary)	2.0%	[0.2%, 4.1%]	12
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.2%, 0.7%]	18

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)	0.9%	[0.9%, 0.9%]	2
Improvements ✅ (primary)	-2.8%	[-2.8%, -2.8%]	1
Improvements ✅ (secondary)	-3.2%	[-3.8%, -2.4%]	4
All ❌✅ (primary)	-2.8%	[-2.8%, -2.8%]	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)	2.8%	[2.1%, 4.9%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 666.532s -> 665.384s (-0.17%)
Artifact size: 308.23 MiB -> 308.26 MiB (0.01%)

[Mark-Simulacrum]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 6785738 with merge b01358a...

[bors]

☀️ Try build successful - checks-actions
Build commit: b01358a (b01358a8a46e428d229b1454567a449404dcf604)

[rust-timer]

Finished benchmarking commit (b01358a): comparison URL.

Overall result: no relevant changes - 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 benchmark run did not return any relevant results for this metric.

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)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	2.2%	[1.1%, 4.3%]	6
Improvements ✅ (primary)	-2.8%	[-2.8%, -2.8%]	1
Improvements ✅ (secondary)	-1.4%	[-1.4%, -1.4%]	1
All ❌✅ (primary)	0.0%	[-2.8%, 2.8%]	2

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)	2.2%	[2.2%, 2.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 664.881s -> 664.279s (-0.09%)
Artifact size: 308.33 MiB -> 308.36 MiB (0.01%)

[Mark-Simulacrum]

Alright, that eliminated the regression in perf benchmarks and this still is a significant win for the toy examples in #50994 and #86244, so I think this is ready to be reviewed.

I'm not sure how I feel about the additional complexity here for what is relatively speaking a pretty rare case... but I don't see trivial ways to make things cleaner and it does seem like the pathological cases could be seen in practical programs (e.g., due to macros emitting a bunch of promoteds and a large function).

[davidtwco]

This seems reasonable to me

[davidtwco]

r=me after rebase

[Mark-Simulacrum]

@bors r=davidtwco

[bors]

📌 Commit c3364a2 has been approved by davidtwco

It is now in the queue for this repository.

[bors]

⌛ Testing commit c3364a2 with merge 227abac...

[bors]

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing 227abac to master...

[rust-timer]

Finished benchmarking commit (227abac): comparison URL.

Overall result: ❌ regressions - 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)	1.5%	[1.5%, 1.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
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)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	2.3%	[1.8%, 2.8%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-3.5%, -2.4%]	2
All ❌✅ (primary)	2.6%	[2.6%, 2.6%]	1

Cycles

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

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)	-	-	0
Improvements ✅ (primary)	-0.5%	[-0.5%, -0.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.5%	[-0.5%, -0.5%]	1

Bootstrap: 665.922s -> 665.464s (-0.07%)
Artifact size: 308.32 MiB -> 308.33 MiB (0.00%)