Check for asm support in UI tests that require it

[tmiasko]

Add needs-asm-support compiletest directive, and use it in asm tests
that require asm support without relying on any architecture specific
features.

Closes #84038.

[rust-highfive]

r? @Mark-Simulacrum

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[Mark-Simulacrum]

Hm, I wonder if we should avoid limiting to just x86_64 - regardless, I would like to see the comment annotated with why we're requiring that target/platform.

r? @Amanieu

[tmiasko]

We could add needs-asm-support directive in compiletest.

[Amanieu]

All the other asm tests do this. The main reason is that, although the specific functionality that is being tested is not arch-specific, we still need to pick an architecture that supports asm!.

For simplicity we only run the tests on x86_64 to ensure they are tested by CI. The arch-specific parts of asm! are tested in src/test/assembly/asm which uses #![no_core] to ensure the tests are always run no matter the host arch.

[Mark-Simulacrum]

Makes sense, OK. I think comments or using something like needs-asm-support would be good, but not necessarily blockers.

[Amanieu]

@bors r+

[bors]

📌 Commit 5e87f97 has been approved by Amanieu

[Dylan-DPC-zz]

failed in rollup

@bors r-

[Amanieu]

@bors r+

[bors]

📌 Commit da40e69 has been approved by Amanieu

[bors]

⌛ Testing commit da40e69 with merge 2e7eb85...

[bors]

☀️ Test successful - checks-actions
Approved by: Amanieu
Pushing 2e7eb85 to master...