[llvm] [ARM][TableGen][MC] Change the ARM mnemonic operands to be optional for ASM parsing (PR #83436)

[Peter Smith via llvm-commits]

smithp35 wrote:

It does look like GCC will accept these alternative forms. I expect that this will have been an unofficial/undocumented bit of GCC behaviour that clang has copied.




https://github.com/llvm/llvm-project/pull/83436