Use unstable_target_features when checking inline assembly

[Amanieu]

This is necessary to properly validate register classes even when the relevant target feature name is still unstable.

[rustbot]

r? @b-naber

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[rustbot]

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo

[compiler-errors]

Is there a test for this? Or an issue to link?

[Amanieu]

This was mostly caught by checking that asm consistently uses unstable_target_features instead of target_features.

The new form is "more correct" since it matches other uses of target features for inline asm checking, but I couldn't figure out an example of where this actually makes a difference in codegen.

[b-naber]

Does seem reasonable to me, but I'm not sure I fully understand the implications of this change.

r? @oli-obk mabye?

[rustbot]

Could not assign reviewer from: oli-obk.
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[b-naber]

r? compiler

[davidtwco]

It would be great if we could add a test for this, but this has been open a while and is a very small change so I'll approve.

[davidtwco]

@bors r+

[bors]

📌 Commit a3ab31c has been approved by davidtwco

It is now in the queue for this repository.

[bors]

⌛ Testing commit a3ab31c with merge c1699a7...

[bors]

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing c1699a7 to master...

[rust-timer]

Finished benchmarking commit (c1699a7): 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)	-	-	0
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-2.3%	[-2.7%, -2.0%]	3
Improvements ✅ (secondary)	-2.1%	[-2.1%, -2.1%]	1
All ❌✅ (primary)	-2.3%	[-2.7%, -2.0%]	3

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: 632.523s -> 633.856s (0.21%)
Artifact size: 346.66 MiB -> 346.73 MiB (0.02%)