Do not include transitive uses with none ownership during ownership rauw of guaranteed values

When we are populating transitive users while handling guaranteed values
in ownership rauw, we were including values with none ownership.

Example : rauw of %2 with a dominating value
   Here %arg1 was also considered a transitive use

   %2 = struct_extract %0 : $StructWithEnum2, #StructWithEnum2.val
   %copy = copy_value %2 : $FakeOptional2
   switch_enum %2 : $FakeOptional2, case #FakeOptional2.some1!enumelt:bb5, case #FakeOptional2.some2!enumelt:bb6

  bb5(%arg1 : $UInt):
   br bb7(%arg1 : $UInt)

  bb6(%arg2 : @guaranteed $Klass):
   %4 = unchecked_trivial_bit_cast %arg2 : $Klass to $UInt
   br bb7(%4 : $UInt)

This is incorrect because %arg1 is a trivial value, and this also
leads to ValueLifetimeAnalysis needing a split for finding a frontier
for the use of %arg1 in the branch instruction. In ossa, we should never
have to split edges for finding frontiers, because we do not have critical
edges.

Author: meg-gupta

lib/SILOptimizer/Utils/OwnershipOptUtils.cpp

@@ -391,7 +391,7 @@ insertOwnedBaseValueAlongBranchEdge(BranchInst *bi, SILValue innerCopy,
   return phiArg;
 }
 
-static void getAllBorrowedValueUsePoints(
+static void getAllNonTrivialUsePointsOfBorrowedValue(
     SILValue value, SmallVectorImpl<Operand *> &usePoints,
     SmallVectorImpl<BorrowingOperand> &reborrowPoints) {
   assert(value.getOwnershipKind() == OwnershipKind::Guaranteed);
@@ -407,6 +407,9 @@ static void getAllBorrowedValueUsePoints(
   for (unsigned i = firstOffset; i < usePoints.size(); ++i) {
     if (auto fOperand = ForwardingOperand::get(usePoints[i])) {
       fOperand->visitForwardedValues([&](SILValue transitiveValue) {
+        // Do not include transitive uses with 'none' ownership
+        if (transitiveValue.getOwnershipKind() == OwnershipKind::None)
+          return true;
         for (auto *transitiveUse : transitiveValue->getUses())
           usePoints.push_back(transitiveUse);
         return true;
@@ -685,8 +688,8 @@ SILBasicBlock::iterator OwnershipRAUWUtility::handleGuaranteed() {
   // workspace.
   SmallVector<Operand *, 32> usePoints;
   SmallVector<BorrowingOperand, 8> recursiveBorrowScopeReborrows;
-  getAllBorrowedValueUsePoints(oldValue, usePoints,
-                               recursiveBorrowScopeReborrows);
+  getAllNonTrivialUsePointsOfBorrowedValue(oldValue, usePoints,
+                                           recursiveBorrowScopeReborrows);
 
   // If we have any transitive reborrows on sub-borrows.
   if (recursiveBorrowScopeReborrows.size())