Clear context in ownership rauw when we cannot fix ownership for rauw.

If not, subsequent unrelated call of OwnershipRAUWHelper::perform will have stale
entries for transitiveBorrowedUses etc

Author: meg-gupta

lib/SILOptimizer/Utils/OwnershipOptUtils.cpp

@@ -241,8 +241,11 @@ static bool canFixUpOwnershipForRAUW(SILValue oldValue, SILValue newValue,
   if (oldValue.getOwnershipKind() == OwnershipKind::Guaranteed) {
     // Check that the old lifetime can be extended and record the necessary
     // book-keeping in the OwnershipFixupContext.
-    return findTransitiveBorrowedUses(oldValue, context.transitiveBorrowedUses,
-                                      context.recursiveReborrows);
+    if (!findTransitiveBorrowedUses(oldValue, context.transitiveBorrowedUses,
+                                    context.recursiveReborrows)) {
+      context.clear();
+      return false;
+    }
   }
   return true;
 }

test/SILOptimizer/cse_ossa_nontrivial.sil

@@ -630,3 +630,34 @@ bb3(%borrow : @guaranteed $Klass):
   return %copy : $NonTrivialStruct 
 }
 
+// Test to make sure we clear the context if we fail while checking if ownership rauw is possible
+// CHECK-LABEL: sil [ossa] @test_rauwfailsandthensucceeds :
+// CHECK: bb0
+// CHECK: struct_extract
+// CHECK: struct_extract
+// CHECK: struct $_SliceBuffer
+// CHECK-NOT: struct $_SliceBuffer
+// CHECK-LABEL: } // end sil function 'test_rauwfailsandthensucceeds'
+sil [ossa] @test_rauwfailsandthensucceeds : $@convention(method) <Element> (UnsafeMutablePointer<Element>, @guaranteed _ContiguousArrayBuffer<Element>, Int, UInt) -> @owned _SliceBuffer<Element> {
+bb0(%0 : $UnsafeMutablePointer<Element>, %1 : @guaranteed $_ContiguousArrayBuffer<Element>, %2 : $Int, %3 : $UInt):
+  %4 = struct_extract %1 : $_ContiguousArrayBuffer<Element>, #_ContiguousArrayBuffer._storage
+  %5 = copy_value %4 : $__ContiguousArrayStorageBase
+  %6 = init_existential_ref %5 : $__ContiguousArrayStorageBase : $__ContiguousArrayStorageBase, $AnyObject
+  %7 = struct_extract %1 : $_ContiguousArrayBuffer<Element>, #_ContiguousArrayBuffer._storage
+  %8 = ref_tail_addr %7 : $__ContiguousArrayStorageBase, $Element
+  %9 = address_to_pointer %8 : $*Element to $Builtin.RawPointer
+  %10 = struct $UnsafeMutablePointer<Element> (%9 : $Builtin.RawPointer)
+  %11 = begin_borrow %6 : $AnyObject
+  %12 = struct $_SliceBuffer<Element> (%11 : $AnyObject, %0 : $UnsafeMutablePointer<Element>, %2 : $Int, %3 : $UInt)
+  %13 = copy_value %12 : $_SliceBuffer<Element>
+  end_borrow %11 : $AnyObject
+  destroy_value %13 : $_SliceBuffer<Element>
+  %14 = begin_borrow %6 : $AnyObject
+  %15 = struct $_SliceBuffer<Element> (%14 : $AnyObject, %0 : $UnsafeMutablePointer<Element>, %2 : $Int, %3 : $UInt)
+  %16 = copy_value %15 : $_SliceBuffer<Element>
+  end_borrow %14 : $AnyObject
+  %17 = struct $_SliceBuffer<Element> (%6 : $AnyObject, %0 : $UnsafeMutablePointer<Element>, %2 : $Int, %3 : $UInt)
+  destroy_value %17 : $_SliceBuffer<Element>
+  return %16 : $_SliceBuffer<Element>
+}
+