Lint more overlapping assignments in MIR.

[cjgillot]

In an effort to make bugs like #146383 more easily discovered, this PR extends the "overlapping assignment" MIR lint.

I had to whitelist some rvalues, as they are actually allowed to alias, like a = a + 1.

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[rustbot]

r? @saethlin

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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

[saethlin]

@bors r+ rollup

-Zlint-mir is off by default so this shouldn't be capable of causing perf impacts.

[bors]

📌 Commit acf0615 has been approved by saethlin

It is now in the queue for this repository.

[Zalathar]

This has a soft conflict with #146564, so I'm going to temporarily remove this PR from the queue to help the more-bitrotty PR land first.

@bors r-

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[saethlin]

I think this is in the clear now?

@bors r+

[bors]

📌 Commit 912785d has been approved by saethlin

It is now in the queue for this repository.

[Kobzol]

@rust-timer build a7976cf

Perf. run for #146698.

[rust-timer]

Finished benchmarking commit (a7976cf): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary 4.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.8%	[4.4%, 5.3%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -0.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.5%	[3.4%, 3.6%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.1%	[-4.3%, -2.2%]	3
All ❌✅ (primary)	-	-	0

Binary size

Results (secondary -0.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-	-	0

Bootstrap: 471.663s -> 470.424s (-0.26%)
Artifact size: 387.94 MiB -> 388.21 MiB (0.07%)