Deduce the "returned" argument attribute by collecting all potentially
Note: Not only the unique return value, if any, can be used by
subsequent attributes but also the set of all potentially returned
values as well as the mapping from returned values to return
instructions that they originate from.
Change in statistics (-stats) for LLVM-TS + Spec2006, totaling ~14% more "returned" arguments.
ADDED: attributor NumAttributesManifested n/a -> 610 ADDED: attributor NumAttributesValidFixpoint n/a -> 25385 ADDED: attributor NumFnArgumentReturned n/a -> 610 ADDED: attributor NumFnKnownReturns n/a -> 25385 ADDED: attributor NumFnUniqueReturned n/a -> 13265 REMOVED: functionattrs NumReturned 535 -> n/a CHANGED: indvars NumElimIdentity 125 -> 151 ( +20.800%)