make mir dataflow graphviz dumps opt-in

[lqd]

This should save some MIR traversals and allocations that are not really needed.

Small win but noticeable locally. Let's see what LTO/PGO say.

r? @ghost

[lqd]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 9395e27 with merge ec22fd018cf26f422e5014619d319a33e12a7f27...

[bors]

☀️ Try build successful - checks-actions
Build commit: ec22fd018cf26f422e5014619d319a33e12a7f27 (ec22fd018cf26f422e5014619d319a33e12a7f27)

[rust-timer]

Finished benchmarking commit (ec22fd018cf26f422e5014619d319a33e12a7f27): 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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.2%]	9
Improvements ✅ (secondary)	-0.4%	[-0.5%, -0.2%]	9
All ❌✅ (primary)	-0.3%	[-0.5%, -0.2%]	9

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)	3.3%	[3.3%, 3.3%]	1
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.3%	[-0.1%, 2.8%]	2

Cycles

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

Binary size

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

Bootstrap: 648.428s -> 649.822s (0.21%)

[lqd]

While the feature seems useful for debugging, it need not impact the happy path. So I think this change makes some sense, what do you think: r? @tmiasko.

[tmiasko]

@bors r+

[bors]

📌 Commit 9395e27 has been approved by tmiasko

It is now in the queue for this repository.

[bors]

⌛ Testing commit 9395e27 with merge c911e08...

[bors]

☀️ Test successful - checks-actions
Approved by: tmiasko
Pushing c911e08 to master...

[rust-timer]

Finished benchmarking commit (c911e08): 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)	0.6%	[0.6%, 0.7%]	3
Regressions ❌ (secondary)	0.6%	[0.6%, 0.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.5%	[-0.6%, -0.4%]	6
All ❌✅ (primary)	0.6%	[0.6%, 0.7%]	3

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
Improvements ✅ (primary)	-1.6%	[-1.6%, -1.6%]	1
Improvements ✅ (secondary)	-2.8%	[-2.8%, -2.8%]	1
All ❌✅ (primary)	-1.6%	[-1.6%, -1.6%]	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)	1.3%	[1.3%, 1.3%]	1
Regressions ❌ (secondary)	2.4%	[2.4%, 2.4%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.3%	[1.3%, 1.3%]	1

Binary size

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

Bootstrap: 656.587s -> 656.978s (0.06%)

[Kobzol]

The helloworld changes are noise, it also happened on other PRs recently.

@rustbot label: +perf-regression-triaged