[LLVMdev] PassManager Mysteries

[David Greene]

I've never been able to figure this one out:

llvm/lib/VMCore/PassManager.cpp:938: virtual void 
llvm::PMDataManager::addLowerLevelRequiredPass(llvm::Pass*, llvm::Pass*): 
Assertion `0 && "Unable to handle Pass that requires lower level Analysis 
pass"' failed.

In the past, I've resolved this by disabling random addRequired calls in the
offending Pass, even when those dependencies are real.

So what does this assert mean, exactly?  How do I find out just what is wrong
with the Pass dependencies?

                                             -Dave