ObjectOutliner: fix for handling set_deallocating instruction correctly.

rdar://problem/36692828

Author: eeckstein

lib/SILOptimizer/Transforms/ObjectOutliner.cpp

@@ -377,24 +377,26 @@ bool ObjectOutliner::optimizeObjectAllocation(
   // Replace the alloc_ref by global_value + strong_retain instructions.
   SILBuilder B(ARI);
   GlobalValueInst *GVI = B.createGlobalValue(ARI->getLoc(), Glob);
-  bool hasToRetain = true;
+  B.createStrongRetain(ARI->getLoc(), GVI, B.getDefaultAtomicity());
   llvm::SmallVector<Operand *, 8> Worklist(ARI->use_begin(), ARI->use_end());
   while (!Worklist.empty()) {
     auto *Use = Worklist.pop_back_val();
     SILInstruction *User = Use->getUser();
     switch (User->getKind()) {
-      case SILInstructionKind::DeallocRefInst:
       case SILInstructionKind::SetDeallocatingInst:
-        hasToRetain = false;
+        // set_deallocating is a replacement for a strong_release. Therefore
+        // we have to insert a strong_release to balance the strong_retain which
+        // we inserted after the global_value instruction.
+        B.setInsertionPoint(User);
+        B.createStrongRelease(User->getLoc(), GVI, B.getDefaultAtomicity());
+        LLVM_FALLTHROUGH;
+      case SILInstructionKind::DeallocRefInst:
         ToRemove.push_back(User);
         break;
       default:
         Use->set(GVI);
     }
   }
-  if (hasToRetain) {
-    B.createStrongRetain(ARI->getLoc(), GVI, B.getDefaultAtomicity());
-  }
   if (FindStringCall && NumTailElems > 16) {
     assert(&*std::next(ARI->getIterator()) != FindStringCall &&
            "FindStringCall must not be the next instruction after ARI because "

test/SILOptimizer/globalopt-iter.sil

@@ -8,13 +8,16 @@ class E : B { }
 
 // CHECK: sil @patatino : $@convention(thin) () -> () {
 // CHECK: bb0:
-// CHECK:   %0 = global_value @patatinoTv_ : $B
-// CHECK:   %1 = tuple ()
-// CHECK:   return %1 : $()
-// CHECK: }
+// CHECK-NEXT:   %0 = global_value @patatinoTv_ : $B
+// CHECK-NEXT:   strong_retain
+// CHECK-NEXT:   strong_release
+// CHECK-NEXT:   tuple ()
+// CHECK-NEXT:   return
+// CHECK-NEXT: }
 
 sil @patatino : $@convention(thin) () -> () {
   %1 = alloc_ref [stack] $B
+  set_deallocating %1 : $B
   dealloc_ref [stack] %1 : $B
   %45 = tuple ()
   return %45 : $()

test/SILOptimizer/objectoutliner.sil

@@ -76,7 +76,9 @@ bb0:
 
 // CHECK-LABEL: sil @handle_deallocation
 // CHECK:      global_value
+// CHECK-NEXT: strong_retain
 // CHECK-NEXT: ref_element_addr
+// CHECK-NEXT: strong_release
 // CHECK-NEXT: tuple
 // CHECK-NEXT: return
 sil @handle_deallocation : $@convention(thin) () -> () {