Choosing a "cfi" instead of the default "tmp" makes the intend clearer in an assembly dump.
More importantly: The dumps are more stable. The temp label numbers don't move around anymore when unrelated code calls
createTempSymbol() more or less often.
Temp labels names do not influence the generated object code (just the assembly output).
This is part of an effort to productize machine module passes. The goal here is to have llvm codegen produce the same output with/without a dummy machine module pass inserted into the pipeline.