LifetimeDependenceDiagnostics: cleanup. remove unused code.

Author: atrick

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/LifetimeDependenceInsertion.swift

@@ -181,63 +181,3 @@ private func insertMarkDependencies(value: Value, initializer: Instruction?,
     currentValue = markDep
   }
 }
-
-/*
-/// Return base values that this return value depends on.
-///
-/// For lifetime copies, walk up the dependence chain to find the
-/// dependence roots, inserting dependencies for any
-/// LifetimeDependentApply.
-private func recursivelyFindDependenceBases(of apply: LifetimeDependentApply,
-                                            _ context: FunctionPassContext)
-  -> [Value] {
-  log("Creating dependencies for \(apply.applySite)")
-  var bases: [Value] = []
-  for lifetimeArg in apply.getLifetimeArguments() {
-    switch lifetimeArg.convention {
-    case .inherit:
-      // Inherit the argument's lifetime dependence by finding the
-      // roots.  This requires that a mark_dependence [nonescaping]
-      // already be created for any earlier LifetimeDependentApply.
-      _ = LifetimeDependence.visitDependenceRoots(enclosing: lifetimeArg.value,
-                                                  context)
-      { (scope: LifetimeDependence.Scope) in
-        if let updatedScope = recursivelyUpdate(scope: scope, context) {
-          log("Inherited lifetime from \(lifetimeArg.value)")
-          log("  depends on: \(updatedScope)")
-          bases.append(updatedScope.parentValue)
-        }
-        return .continueWalk
-      }
-    case .scope:
-      // Create a new dependence on the apply's access to the argument.
-      if let scope =
-           LifetimeDependence.Scope(base: lifetimeArg.value, context) {
-        log("Scoped lifetime from \(lifetimeArg.value)")
-        log("  scope: \(scope)")
-        bases.append(scope.parentValue)
-      }
-    }
-  }
-  return bases
-}
-
-// Recursively insert dependencies, assuming no cycle of dependent applies.
-//
-// TODO: needs unit test.
-private func recursivelyUpdate(scope: LifetimeDependence.Scope,
-  _ context: FunctionPassContext) -> LifetimeDependence.Scope? {
-  if let dependentApply =
-    LifetimeDependentApply(withResult: scope.parentValue) {
-    insertDependencies(for: dependentApply, context)
-    // If a mark_dependence [nonescaping] was created for this apply,
-    // then return it as the updated dependence. Otherwise, return the
-    // original dependence.
-    if let markDep = scope.parentValue.uses.singleUse?.instruction
-      as? MarkDependenceInst {
-      return LifetimeDependence(markDep, context)?.scope
-    }
-  }
-  return scope
-}
-*/