[llvm] [SPIR-V][Codegen] Add isPhi bit to MCInstrDesc/MIR definitions (PR #110019)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

Thanks @VyacheslavLevytskyy for the reply.

After some discussions with a colleague, looks like there is another way which spares this precious bit: adding the info into TargetInstrInfo, and using this to check the opcode/offset.
Updated the PR to match this new version. Running tests now to verify my implementation, and will update this PR.


https://github.com/llvm/llvm-project/pull/110019