Skip threading over no-op SetDiscriminant.

[cjgillot]

Fixes #119674

[rustbot]

r? @oli-obk

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[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[tmiasko]

@bors r+

[bors]

📌 Commit 41eb9a4 has been approved by tmiasko

It is now in the queue for this repository.

[bors]

⌛ Testing commit 41eb9a4 with merge 75c68cf...

[bors]

☀️ Test successful - checks-actions
Approved by: tmiasko
Pushing 75c68cf to master...

[rust-timer]

Finished benchmarking commit (75c68cf): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

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)	3.2%	[3.2%, 3.2%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.2%	[3.2%, 3.2%]	1

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: 666.132s -> 665.982s (-0.02%)
Artifact size: 308.40 MiB -> 308.42 MiB (0.00%)