[llvm] [Hexagon] Provide a custom decoder for Y4_crswap10 (PR #153849)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> In Hexagon, similar cases are handled in a switch inside `HexagonDisassembler::getSingleInstruction`, look for `J4_cmpeqn1_f_jumpnv_nt` and others.

Thanks for the pointer, I'll do it there for consistency.

>  I don't know if there is a valid method in LLVM in general to create a fake operand without overriding the whole instruction.

There isn't. Some targets override DecoderMethod, others go the Hexagon way of adding missing operands after decoding is complete. I'm working on fixing this (and this is how I found the bug).


https://github.com/llvm/llvm-project/pull/153849