[LLVMdev] Adding ARM UDF / UND instruction to TableGen

Tim Northover t.p.northover at gmail.com
Sun Mar 31 10:52:18 PDT 2013

Hi Gordon,

> Does anyone have a preference for this?

I'd prefer going along with the documentation. If someone sees "UDF"
and doesn't know what it means they can look it up the same place as
any other instruction (the ARM architecture reference manual). If they
see "UND" they'd have less options.

> and adding an alias of UDF for assembly purposes.

Having an alias supporting both for assembly sounds like a good idea.

> Do any other assemblers even recognize this instruction by name?

Surprisingly, the ARM assembler itself seems to accept "UND" but not
"UDF" and can't disassemble either. Don't know about any others.


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