fix autodiff compile time regression

[ZuseZ4]

Tries to fix the regression from #133429

Tracking:

• Tracking Issue for autodiff #124509

[rustbot]

r? @petrochenkov

rustbot has assigned @petrochenkov.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[ZuseZ4]

Well fair enough, if I add r? @oli-obk in the homu-ignore section it will be ignored.

[workingjubilee]

derp.

[workingjubilee]

@bors try

[bors]

⌛ Trying commit 199ef41 with merge 719d8b8...

[bors]

☀️ Try build successful - checks-actions
Build commit: 719d8b8 (719d8b829f49aa1a90d25afcf05631f8db213bc4)

[workingjubilee]

@rust-timer queue

[lqd]

@rust-timer build 719d8b8

[rust-timer]

Finished benchmarking commit (719d8b8): 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 the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-30.3%	[-30.7%, -29.8%]	4
Improvements ✅ (secondary)	-30.0%	[-31.9%, -28.2%]	2
All ❌✅ (primary)	-30.3%	[-30.7%, -29.8%]	4

Max RSS (memory usage)

Results (secondary -2.2%)

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)	-2.2%	[-2.2%, -2.2%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (primary -31.0%, secondary -10.4%)

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)	3.4%	[2.3%, 5.6%]	3
Improvements ✅ (primary)	-31.0%	[-31.3%, -30.3%]	4
Improvements ✅ (secondary)	-31.3%	[-32.8%, -29.7%]	2
All ❌✅ (primary)	-31.0%	[-31.3%, -30.3%]	4

Binary size

Results (primary -0.1%, secondary 0.6%)

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)	0.0%	[0.0%, 0.0%]	3
Regressions ❌ (secondary)	0.6%	[0.6%, 0.6%]	2
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.1%	[-0.4%, 0.0%]	4

Bootstrap: 777.275s -> 777.68s (0.05%)
Artifact size: 328.69 MiB -> 328.71 MiB (0.01%)

[ZuseZ4]

Bingo.

[ZuseZ4]

We had a 43% primary regression, and here a 30% primary improvement.
143%*0.7=100.1%
Looks like my math lectures weren't completely useless.