[LLVMdev] runOnFunction() being called many times on the same function

[John Regehr]

I have a FunctionPass that is being scheduled by the legacy pass manager 
using EP_OptimizerLast.  It is an instrumentation pass that makes a 
function bigger.  The problem is that runOnFunction() is being called 
many times for the same function, resulting in runaway growth and 
eventual OOM for the clang process.

I see that sanitizer passes are using EP_OptimizerLast, so obviously the 
capacity to run once is available.  Is there some mistake I might be 
making that would cause LLVM to do this?  If not, can someone let me 
know how to tell LLVM to call runOnFunction() only one time for each 
function?

This behavior does not happen for all functions or in all files, and it 
seems to be more common on Linux than Mac.  So perhaps an LLVM bug of 
some sort?

I see the same behavior using r238200 and r240137.

Thanks,

John