[llvm-dev] Invalid llvm-ir and unreachable code

[Jeroen Dobbelaere via llvm-dev]

Hi all,

I have found a case where an optimization pass is barfing on invalid code in an unreachable
basic block. A self referencing GEP '%x = getelementptr %x, 0, 1' is found inside a cycle of
two unreachable basic blocks)

The invalid code and the unreachable basic blocks were introduced by the function inliner.

I am wondering what is valid for these cases ?
(I did not find anything in LangRef, but I might as well have missed it)

- clearly 'dead code' (aka unreachable basic blocks) is valid in an IR ?
- I assume that the self reference in dead code is not valid ?
- should inlining do an extra effort of cleaning up such dead code blocks ?

Thanks,

Jeroen Dobbelaere