SILOptimizer: remove the unused findApplyFromDevirtualizedResult utility function

Author: eeckstein

include/swift/SILOptimizer/Utils/InstOptUtils.h

@@ -260,8 +260,6 @@ getConcreteValueOfExistentialBox(AllocExistentialBoxInst *existentialBox,
 SILValue getConcreteValueOfExistentialBoxAddr(SILValue addr,
                                               SILInstruction *ignoreUser);
 
-FullApplySite findApplyFromDevirtualizedResult(SILValue value);
-
 /// Cast a value into the expected, ABI compatible type if necessary.
 /// This may happen e.g. when:
 /// - a type of the return value is a subclass of the expected return type.

lib/SILOptimizer/Utils/InstOptUtils.cpp

@@ -810,20 +810,6 @@ getConcreteValueOfExistentialBoxAddr(SILValue addr, SILInstruction *ignoreUser)
   return getConcreteValueOfExistentialBox(box, singleStackStore);
 }
 
-// Devirtualization of functions with covariant return types produces
-// a result that is not an apply, but takes an apply as an
-// argument. Attempt to dig the apply out from this result.
-FullApplySite swift::findApplyFromDevirtualizedResult(SILValue v) {
-  if (auto Apply = FullApplySite::isa(v))
-    return Apply;
-
-  if (isa<UpcastInst>(v) || isa<EnumInst>(v) || isa<UncheckedRefCastInst>(v))
-    return findApplyFromDevirtualizedResult(
-        cast<SingleValueInstruction>(v)->getOperand(0));
-
-  return FullApplySite();
-}
-
 bool swift::mayBindDynamicSelf(SILFunction *F) {
   if (!F->hasDynamicSelfMetadata())
     return false;