[silgen] When checking we check if a failable initializer that we delegated to returned null, reload self using the normal semantics.

We have already finished the delegation sequence at this point, so we should go
through normal semantics.

rdar://33358110

Author: gottesmm

lib/SILGen/SILGenExpr.cpp

@@ -3473,8 +3473,20 @@ RValue RValueEmitter::visitRebindSelfInConstructorExpr(
       !calledCtor->isImplicit() &&
       usesObjCAllocator(classDecl)) {
 
-    // Check whether the new self is null.
-    SILValue isNonnullSelf = SGF.B.createIsNonnull(E, newSelf.getValue());
+    // Check whether the new self is null. *NOTE* At this point, we can not
+    // access the actual new value using newSelf anymore. We need to grab self
+    // via the normal manner of doing so.
+    SILValue isNonnullSelf;
+    {
+      Scope S(SGF, E);
+      RValue selfRValue =
+          SGF.emitRValueForDecl(E, selfDecl, selfTy->getCanonicalType(),
+                                AccessSemantics::DirectToStorage,
+                                SGFContext::AllowGuaranteedPlusZero);
+      ManagedValue reloadedSelf =
+          std::move(selfRValue).getAsSingleValue(SGF, E);
+      isNonnullSelf = SGF.B.createIsNonnull(E, reloadedSelf.getValue());
+    }
     Condition cond = SGF.emitCondition(isNonnullSelf, E, 
                                        /*hasFalseCode=*/false,
                                        /*invertValue=*/true,

test/SILGen/objc_thunks.swift

@@ -427,7 +427,9 @@ extension Hoozit {
     // CHECK: [[CTOR:%[0-9]+]] = class_method [volatile] [[SELF:%[0-9]+]] : $Hoozit, #Hoozit.init!initializer.1.foreign : (Hoozit.Type) -> (Int) -> Hoozit, $@convention(objc_method) (Int, @owned Hoozit) -> @owned Hoozit
     // CHECK: [[NEW_SELF:%[0-9]+]] = apply [[CTOR]]
     // CHECK: store [[NEW_SELF]] to [init] [[PB_BOX]] : $*Hoozit
-    // CHECK: [[NONNULL:%[0-9]+]] = is_nonnull [[NEW_SELF]] : $Hoozit
+    // CHECK: [[RELOADED_SELF:%.*]] = load_borrow [[PB_BOX]]
+    // CHECK: [[NONNULL:%[0-9]+]] = is_nonnull [[RELOADED_SELF]] : $Hoozit
+    // CHECK: end_borrow [[RELOADED_SELF]] from [[PB_BOX]]
     // CHECK-NEXT: cond_br [[NONNULL]], [[NONNULL_BB:bb[0-9]+]], [[NULL_BB:bb[0-9]+]]
     // CHECK: [[NULL_BB]]:
     // CHECK-NEXT: destroy_value [[X_BOX]] : ${ var X }