Turn moves into copies after copy propagation

[tmiasko]

Previously copy propagation presumed that there is further unspecified distinction between move operands and copy operands in assignments and propagated moves from assignments into terminators. This is inconsistent with current operational semantics.

Turn moves into copies after copy propagation to preserve existing behavior.

Fixes #137936.
Fixes #146423.

r? @cjgillot

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[tmiasko]

@bors2 try @rust-timer queue

[rust-bors]

💥 Test timed out after 21600s

[tmiasko]

@bors try

[rust-bors]

☀️ Try build successful (CI)
Build commit: 09003ac (09003acc28104d3fbe9b443536d97a793f68ffde, parent: f46475914de626785090a05ae037578aaa119fc8)

[rust-timer]

Finished benchmarking commit (09003ac): comparison URL.

Overall result: ❌ regressions - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@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)	1.2%	[0.2%, 3.6%]	39
Regressions ❌ (secondary)	1.8%	[0.3%, 10.1%]	21
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	1.2%	[0.2%, 3.6%]	39

Max RSS (memory usage)

Results (primary 1.5%, secondary 4.1%)

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

	mean	range	count
Regressions ❌ (primary)	1.5%	[1.5%, 1.5%]	1
Regressions ❌ (secondary)	4.1%	[4.1%, 4.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.5%	[1.5%, 1.5%]	1

Cycles

Results (primary -0.5%, secondary 5.5%)

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

	mean	range	count
Regressions ❌ (primary)	1.6%	[1.6%, 1.6%]	1
Regressions ❌ (secondary)	5.5%	[3.5%, 8.9%]	4
Improvements ✅ (primary)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.5%	[-2.6%, 1.6%]	2

Binary size

Results (primary 0.7%, secondary 0.2%)

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

	mean	range	count
Regressions ❌ (primary)	0.7%	[0.0%, 3.3%]	63
Regressions ❌ (secondary)	0.2%	[0.0%, 0.8%]	30
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[0.0%, 3.3%]	63

Bootstrap: 475.372s -> 475.243s (-0.03%)
Artifact size: 390.39 MiB -> 390.39 MiB (0.00%)