They are the same: asm! was replaced by llvm_asm! because it currently only supports llvm asm and the name might suggest otherwise [1]. A backend independant syntax for asm! was recently specified [2], but that will take some time to implement.

[1] https://github.com/rust-lang/rfcs/pull/2843

[2] https://github.com/rust-lang/rfcs/pull/2873

They are not the same, and the asm! version is already implemented; the RFC came with an implementation.

That first PR moved the old asm to llvm_asm, and then the new asm was built after a period of time so folks could migrate their code to llvm_asm, as a temporary measure. This commit happened after that transition so this has to be from the new asm back to the transition version.

Oops, my bad, I was working with an outdated understanding of the situation. Thanks for correcting me.

No problem :) It was a feature that had no changes for a long time, and now has had a bunch of improvements and is finally on a path to stable. It can be hard to keep up with things sometimes.

I couldn't get it working and was familiar with the `llvm_asm!` syntax. Although, I may have to go back and switch it around again.