[LifetimeCompletion] NFC: Add helper.

It visits users discovered by an SSAPrunedLiveness instance (such as
that used by InteriorLiveness) which are outside the LinearLifetime
boundary.

Author: nate-chandler

lib/SIL/Utils/OSSALifetimeCompletion.cpp

@@ -109,6 +109,43 @@ static bool endLifetimeAtLivenessBoundary(SILValue value,
   return changed;
 }
 
+static void visitUsersOutsideLinearLivenessBoundary(
+    SILValue value, const SSAPrunedLiveness &liveness,
+    llvm::function_ref<void(SILInstruction *)> visitor) {
+  if (value->getOwnershipKind() == OwnershipKind::None) {
+    return;
+  }
+  LinearLiveness linearLiveness(value);
+  linearLiveness.compute();
+  for (auto pair : liveness.getAllUsers()) {
+    if (pair.second.isEnding() || isa<ExtendLifetimeInst>(pair.first)) {
+      continue;
+    }
+    auto *user = pair.first;
+    if (linearLiveness.getLiveness().isWithinBoundary(user)) {
+      continue;
+    }
+    visitor(user);
+  }
+}
+
+namespace swift::test {
+// Arguments:
+// - SILValue: value
+// Dumps:
+// - the instructions outside the liveness boundary
+static FunctionTest LivenessPartialBoundaryOutsideUsersTest(
+    "liveness_partial_boundary_outside_users",
+    [](auto &function, auto &arguments, auto &test) {
+      SILValue value = arguments.takeValue();
+      InteriorLiveness liveness(value);
+      liveness.compute(test.getDominanceInfo());
+      visitUsersOutsideLinearLivenessBoundary(
+          value, liveness.getLiveness(),
+          [](auto *inst) { inst->print(llvm::outs()); });
+    });
+} // end namespace swift::test
+
 namespace {
 /// Implements OSSALifetimeCompletion::visitAvailabilityBoundary.  Finds
 /// positions as near as possible to unreachables at which `value`'s lifetime

test/SILOptimizer/ossa_lifetime_completion.sil

@@ -27,6 +27,10 @@ case none
 case some(Wrapped)
 }
 
+typealias AnyObject = Builtin.AnyObject
+
+protocol P : AnyObject {}
+
 // CHECK-LABEL: begin running test 1 of 1 on eagerConsumneOwnedArg: ossa_lifetime_completion with: @argument
 // CHECK-LABEL: OSSA lifetime completion on liveness boundary: %0 = argument of bb0 : $C
 // CHECK: sil [ossa] @eagerConsumneOwnedArg : $@convention(thin) (@owned C) -> () {
@@ -537,3 +541,28 @@ left:
 right:
   unreachable
 }
+
+// CHECK-LABEL: begin running test {{.*}} on loopy: liveness_partial_boundary_outside_users with: %o
+// CHECK:       end_borrow
+// CHECK-LABEL: end running test {{.*}} on loopy: liveness_partial_boundary_outside_users with: %o
+sil [ossa] @loopy : $@convention(thin) () -> () {
+  %o = apply undef() : $@convention(thin) () -> (@owned C)
+  specify_test "liveness_partial_boundary_outside_users %o"
+  %b = begin_borrow %o : $C
+  end_borrow %b : $C
+  br loop
+
+loop:
+  br loop
+}
+
+// CHECK-LABEL: begin running test {{.*}} on type_dependent_operand: liveness_partial_boundary_outside_users
+// There should be no out-of-boundary users.
+// CHECK-NEXT:  end running test {{.*}} on type_dependent_operand: liveness_partial_boundary_outside_users
+sil [ossa] @type_dependent_operand : $@convention(thin) (@owned any P) -> @owned AnyObject {
+bb0(%existential : @owned $any P):
+  %opened = open_existential_ref %existential : $any P to $@opened("00000000-0000-0000-0000-000000000000", any P) Self
+  specify_test "liveness_partial_boundary_outside_users %opened"
+  %ref_existential = init_existential_ref %opened : $@opened("00000000-0000-0000-0000-000000000000", any P) Self : $@opened("00000000-0000-0000-0000-000000000000", any P) Self, $AnyObject
+  return %ref_existential : $AnyObject
+}