[llvm] [SPIRV] Migrate NSDI emission from a machine pass to DebugHandlerBase (PR #191212)

[Steven Perron via llvm-commits]

s-perron wrote:

> It worked around this by scanning the MIR for existing type and constant instructions and reusing their virtual registers as operands, relying on SPIRVModuleAnalysis aliasing those registers to the correct final IDs. 

If we can stop this, I will be dancing in the streets. We cannot remove seemingly dead constant instruction in during instruction selection because the may be needed later. I never did look into the specific places they are needed and how to avoid it. I hope this is the only place this happens.

https://github.com/llvm/llvm-project/pull/191212