Give SILToken Guaranteed ownership.

The begin_apply token represents the borrow scope of all owned and guaranteed
call arguments. Although SILToken is (currently) trivially typed, it must
have guaranteed ownership so end_apply and abort_apply will be recognized
as lifetime-ending uses.

Author: atrick

lib/SIL/IR/OperandOwnership.cpp

@@ -259,6 +259,11 @@ OPERAND_OWNERSHIP(ForwardingBorrow, OpenExistentialValue)
 OPERAND_OWNERSHIP(ForwardingBorrow, OpenExistentialBoxValue)
 
 OPERAND_OWNERSHIP(EndBorrow, EndBorrow)
+
+// The begin_apply token represents the borrow scope of all owned and guaranteed
+// call arguments. Although SILToken is (currently) trivially typed, it must
+// have guaranteed ownership so end_apply and abort_apply will be recognized
+// as lifetime-ending uses.
 OPERAND_OWNERSHIP(EndBorrow, EndApply)
 OPERAND_OWNERSHIP(EndBorrow, AbortApply)
 

lib/SIL/IR/SILInstructions.cpp

@@ -482,7 +482,11 @@ BeginApplyInst::create(SILDebugLocation loc, SILValue callee,
   }
 
   resultTypes.push_back(SILType::getSILTokenType(F.getASTContext()));
-  resultOwnerships.push_back(OwnershipKind::None);
+  // The begin_apply token represents the borrow scope of all owned and
+  // guaranteed call arguments. Although SILToken is (currently) trivially
+  // typed, it must have guaranteed ownership so end_apply and abort_apply will
+  // be recognized as lifetime-ending uses.
+  resultOwnerships.push_back(OwnershipKind::Guaranteed);
 
   SmallVector<SILValue, 32> typeDependentOperands;
   collectTypeDependentOperands(typeDependentOperands, openedArchetypes, F,