asm: Match clang behavior for inlateout fixed register operands

[Amanieu]

We have 2 options for representing LLVM constraints for inlateout operands on a fixed register (e.g. r0): ={r0},0 or ={r0},{r0}.

This PR changes the behavior to the latter, which matches the behavior of Clang since https://reviews.llvm.org/D87279.

[rust-highfive]

r? @cjgillot

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[cjgillot]

I don't know enough about asm to review this, sorry.
r? compiler

[davidtwco]

Likewise, maybe bjorn?

r? @bjorn3

[bjorn3]

I don't know enough about LLVM to know why this would be beneficial/necessary, but it doesn't look like it would break anything either.

@bors r+

[bors]

📌 Commit 6bfe7f0 has been approved by bjorn3

It is now in the queue for this repository.

[bors]

⌛ Testing commit 6bfe7f0 with merge 41812cc416495286dabb10d5270c92cc0b6c9e7f...

[bors]

💔 Test failed - checks-actions

[rust-log-analyzer]

The job mingw-check failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[Amanieu]

Network error
@bors retry

[bors]

⌛ Testing commit 6bfe7f0 with merge 47c008e...

[bors]

☀️ Test successful - checks-actions
Approved by: bjorn3
Pushing 47c008e to master...

[rust-timer]

Finished benchmarking commit (47c008e): 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)	0.9%	[0.5%, 1.1%]	3
Regressions ❌ (secondary)	4.4%	[4.4%, 4.4%]	1
Improvements ✅ (primary)	-0.5%	[-0.5%, -0.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[-0.5%, 1.1%]	4

Cycles

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