Replace ZST operands and debuginfo by constants.

[cjgillot]

This is work that ConstProp will not have to do.
Split from #107267

[rustbot]

r? @Nilstrieb

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

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[Noratrieb]

The change looks good, but I'll give it over to someone more familiar with MIR opts for a second look

r? mir-opt

[oli-obk]

@bors r+

[bors]

📌 Commit f922c5f223e560470ce1dab4218f91acd5a99f67 has been approved by oli-obk

It is now in the queue for this repository.

[oli-obk]

@bors r+

[bors]

📌 Commit 49f4399 has been approved by oli-obk

It is now in the queue for this repository.

[matthiaskrgr]

I think this failed in a rollup? #107327
@bors r-

[cjgillot]

Rebased and blessed the modified test.
@bors r=oli-obk

[bors]

📌 Commit 67270568b5874935958142351802bb0c6e64aeec has been approved by oli-obk

It is now in the queue for this repository.

[bors]

☔ The latest upstream changes (presumably #108872) made this pull request unmergeable. Please resolve the merge conflicts.

[oli-obk]

@bors r+

[bors]

📌 Commit e8afb08 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit e8afb08 with merge e386217...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing e386217 to master...

[rust-timer]

Finished benchmarking commit (e386217): 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)	1.2%	[0.4%, 1.9%]	4
Regressions ❌ (secondary)	0.7%	[0.7%, 0.7%]	1
Improvements ✅ (primary)	-0.5%	[-0.6%, -0.3%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[-0.6%, 1.9%]	7

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)	3.6%	[0.0%, 9.3%]	8
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.2%	[-2.4%, -0.5%]	3
Improvements ✅ (secondary)	-4.4%	[-4.4%, -4.4%]	1
All ❌✅ (primary)	2.3%	[-2.4%, 9.3%]	11

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)	4.1%	[4.0%, 4.2%]	2
Improvements ✅ (primary)	-0.5%	[-0.5%, -0.4%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.5%	[-0.5%, -0.4%]	3

[cjgillot]

Perf report:

• on instruction count: 3 regressions >1% on optimized builds, to balance with many small improvements. On average, +0.14% regression and -0.22% improvements;
• improvement on crate metadata size, on average -0.15% up to 2% ;
• likewise on binary size (-0.22% up to 1%).

[nnethercote]

Yes, it's a mix of results, but overall the wins exceed the losses.

@rustbot label: +perf-regression-triaged