Now that InstCombine canonicalises add+gep to gep+gep, LoopFlatten needs to recognise (gep (gep ptr (i*M)), j) as being something it can optimise.
Now that InstCombine canonicalises add+gep to gep+gep, LoopFlatten needs to recognise (gep (gep ptr (i*M)), j) as being something it can optimise.