[LLVMdev] Adding option to LLVM opt to disable a specific pass from command line

[David Blaikie]

> For instance, I figured out that loop-idiom pass has a BUG in
> LLVM 2.9, a llvm.memcpy is generated for an overlapping memory region and
> then x86 backend reorder loads/store thus generating a BUG.

Just for the record it seems this is a bug in your frontend, not in
the LLVM backend. The memcpy intrinsic, like the standard memcpy
function, requires that the regions be non-overlapping:
http://llvm.org/docs/LangRef.html#int_memcpy By violating this
contract it's possible you'll encounter all sorts of issues in other
passes too.

- David