[llvm] [AMDGPU] Move renamedInGFX9 from TableGen to SIInstrInfo helper function/macro to free up a bit slot (PR #82787)

[Jay Foad via llvm-commits]

jayfoad wrote:

rampitec said:
> I never liked that bit.

arsenm said:
> pseudoToMCOpcode now requires much more manual effort than should really be required.

A better solution for this mess would be to fix the `getMCOpcodeGen` table to support using the same Real for different encoding families, as described above:
> It's because GFX8 and GFX9 use the same Real for some instructions. The obvious way to support this would be to have it directly represented in the getMCOpcodeGen table, i.e. have the same value (Real) in multiple columns (EncodingFamilies) of the same row (Pseudo). But the table is defined with InstrMapping which does not let you do that.

Nicolai previously suggested we could do that by "extending the InstrMapping infrastructure so that column fields in TableGen can be given as lists".

https://github.com/llvm/llvm-project/pull/82787