How to track down a bad llvm optimization pass

[Kagamin via digitalmars-d-ldc]

On Friday, 17 June 2016 at 08:48:01 UTC, David Nadlinger wrote:
> As a general comment, it is of course possible that we are 
> hitting a genuine LLVM bug here, but I'd also be on the lookout 
> for cases where we might be generating invalid IR (in the sense 
> that we trigger some documented undefined behaviour, violate 
> some assumptions, etc.).

Can't it be ruled out by the `opt` tool? Though I thought it's 
strange how it works on ir-to-ir level.