OSSA ownership optimization RAUW utility fixes.

Verify that the OwnershipRAUWUtility always preserves the original
borrow scope by exhaustively switching over OperandOwnership.

And related cleanup.

Author: atrick

include/swift/SIL/OwnershipUtils.h

@@ -76,12 +76,10 @@ inline bool isForwardingConsume(SILValue value) {
 }
 
 class ForwardingOperand {
-  Operand *use;
-
-  ForwardingOperand(Operand *use) : use(use) {}
+  Operand *use = nullptr;
 
 public:
-  static ForwardingOperand get(Operand *use);
+  explicit ForwardingOperand(Operand *use);
 
   OwnershipConstraint getOwnershipConstraint() const {
     // We use a force unwrap since a ForwardingOperand should always have an
@@ -665,25 +663,26 @@ struct InteriorPointerOperand {
     llvm_unreachable("Covered switch isn't covered?!");
   }
 
-  /// Compute the list of implicit uses that this interior pointer operand puts
-  /// on its parent guaranted value.
+  /// Transitively compute the list of uses that this interior pointer operand
+  /// puts on its parent guaranted value.
   ///
   /// Example: Uses of a ref_element_addr can not occur outside of the lifetime
   /// of the instruction's operand. The uses of that address act as liveness
   /// requirements to ensure that the underlying class is alive at all use
   /// points.
-  bool getImplicitUses(SmallVectorImpl<Operand *> &foundUses,
-                       std::function<void(Operand *)> *onError = nullptr) {
-    return getImplicitUsesForAddress(getProjectedAddress(), foundUses, onError);
+  bool findTransitiveUses(SmallVectorImpl<Operand *> &foundUses,
+                          std::function<void(Operand *)> *onError = nullptr) {
+    return findTransitiveUsesForAddress(getProjectedAddress(), foundUses,
+                                        onError);
   }
 
   /// The algorithm that is used to determine what the verifier will consider to
-  /// be implicit uses of the given address. Used to implement \see
-  /// getImplicitUses.
+  /// be transitive uses of the given address. Used to implement \see
+  /// findTransitiveUses.
   static bool
-  getImplicitUsesForAddress(SILValue address,
-                            SmallVectorImpl<Operand *> &foundUses,
-                            std::function<void(Operand *)> *onError = nullptr);
+  findTransitiveUsesForAddress(SILValue address,
+                               SmallVectorImpl<Operand *> &foundUses,
+                               std::function<void(Operand *)> *onError = nullptr);
 
   Operand *operator->() { return operand; }
   const Operand *operator->() const { return operand; }

include/swift/SILOptimizer/Utils/OwnershipOptUtils.h

@@ -38,6 +38,9 @@ struct OwnershipFixupContext {
   DeadEndBlocks &deBlocks;
   JointPostDominanceSetComputer &jointPostDomSetComputer;
 
+  SmallVector<Operand *, 8> transitiveBorrowedUses;
+  SmallVector<BorrowingOperand, 8> recursiveReborrows;
+
   /// Extra state initialized by OwnershipRAUWFixupHelper::get() that we use
   /// when RAUWing addresses. This ensures we do not need to recompute this
   /// state when we perform the actual RAUW.
@@ -67,6 +70,8 @@ struct OwnershipFixupContext {
 
   void clear() {
     jointPostDomSetComputer.clear();
+    transitiveBorrowedUses.clear();
+    recursiveReborrows.clear();
     extraAddressFixupInfo.allAddressUsesFromOldValue.clear();
     extraAddressFixupInfo.intPtrOp = InteriorPointerOperand();
   }

lib/SIL/Utils/OwnershipUtils.cpp

@@ -520,7 +520,7 @@ bool BorrowedValue::visitInteriorPointerOperands(
 //                           InteriorPointerOperand
 //===----------------------------------------------------------------------===//
 
-bool InteriorPointerOperand::getImplicitUsesForAddress(
+bool InteriorPointerOperand::findTransitiveUsesForAddress(
     SILValue projectedAddress, SmallVectorImpl<Operand *> &foundUses,
     std::function<void(Operand *)> *onError) {
   SmallVector<Operand *, 8> worklist(projectedAddress->getUses());
@@ -882,12 +882,12 @@ OwnedValueIntroducer swift::getSingleOwnedValueIntroducer(SILValue inputValue) {
 //                             Forwarding Operand
 //===----------------------------------------------------------------------===//
 
-ForwardingOperand ForwardingOperand::get(Operand *use) {
+ForwardingOperand::ForwardingOperand(Operand *use) {
   if (use->isTypeDependent())
-    return nullptr;
+    return;
 
   if (!OwnershipForwardingMixin::isa(use->getUser())) {
-    return nullptr;
+    return;
   }
 #ifndef NDEBUG
   switch (use->getOperandOwnership()) {
@@ -909,7 +909,7 @@ ForwardingOperand ForwardingOperand::get(Operand *use) {
     llvm_unreachable("this isn't the operand being forwarding!");
   }
 #endif
-  return {use};
+  this->use = use;
 }
 
 ValueOwnershipKind ForwardingOperand::getOwnershipKind() const {
@@ -1008,7 +1008,7 @@ void ForwardingOperand::setOwnershipKind(ValueOwnershipKind newKind) const {
     return;
   }
 
-  llvm_unreachable("Out of sync with ForwardingOperand::get?!");
+  llvm_unreachable("Out of sync with OperandOwnership");
 }
 
 void ForwardingOperand::replaceOwnershipKind(ValueOwnershipKind oldKind,
@@ -1075,7 +1075,7 @@ void ForwardingOperand::replaceOwnershipKind(ValueOwnershipKind oldKind,
     return;
   }
 
-  llvm_unreachable("Missing Case! Out of sync with ForwardingOperand::get?!");
+  llvm_unreachable("Missing Case! Out of sync with OperandOwnership");
 }
 
 SILValue ForwardingOperand::getSingleForwardedValue() const {

lib/SIL/Verifier/SILOwnershipVerifier.cpp

@@ -381,7 +381,7 @@ bool SILValueOwnershipChecker::gatherUsers(
                          << "Address User: " << *op->getUser();
           });
         };
-        foundError |= interiorPointerOperand.getImplicitUses(
+        foundError |= interiorPointerOperand.findTransitiveUses(
             nonLifetimeEndingUsers, &onError);
       }
 

lib/SILOptimizer/SemanticARC/CopyValueOpts.cpp

@@ -331,7 +331,7 @@ static bool canJoinIfCopyDiesInFunctionExitingBlock(
 }
 
 static Operand *lookThroughSingleForwardingUse(Operand *use) {
-  auto forwardingOperand = ForwardingOperand::get(use);
+  ForwardingOperand forwardingOperand(use);
   if (!forwardingOperand)
     return nullptr;
   auto forwardedValue = forwardingOperand.getSingleForwardedValue();
@@ -423,7 +423,7 @@ static bool tryJoinIfDestroyConsumingUseInSameBlock(
     // If not, see if this use did have a forwardedValue but that forwardedValue
     // has multiple end lifetime uses. In that case, we can optimize if there
     // aren't any uses/etc
-    auto forwardingOperand = ForwardingOperand::get(currentForwardingUse);
+    ForwardingOperand forwardingOperand(currentForwardingUse);
     if (!forwardingOperand)
       return false;
     auto forwardedValue = forwardingOperand.getSingleForwardedValue();

lib/SILOptimizer/SemanticARC/OwnershipLiveRange.cpp

@@ -228,7 +228,7 @@ void OwnershipLiveRange::convertOwnedGeneralForwardingUsesToGuaranteed() && {
   while (!ownershipForwardingUses.empty()) {
     auto *use = ownershipForwardingUses.back();
     ownershipForwardingUses = ownershipForwardingUses.drop_back();
-    auto operand = ForwardingOperand::get(use);
+    ForwardingOperand operand(use);
     operand.replaceOwnershipKind(OwnershipKind::Owned,
                                  OwnershipKind::Guaranteed);
   }