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

[Alfie Richards via llvm-commits]

AlfieRichardsArm wrote:

Okay, I will create a ticket for this and pick it up. 

By "trace this back" do you mean find a reference to this in GCC? Or find a source for the previous behavior in LLVM?

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