Merge pull request #10831 from gottesmm/fix_createunsafecopyunowned_value

[silgen] Fix createUnsafeCopyUnownedValue to be correct from an ownership perspective.

Author: gottesmm

lib/SILGen/SILGenBuilder.cpp

@@ -247,11 +247,14 @@ ManagedValue SILGenBuilder::createCopyUnownedValue(SILLocation loc,
 ManagedValue
 SILGenBuilder::createUnsafeCopyUnownedValue(SILLocation loc,
                                             ManagedValue originalValue) {
+  // *NOTE* The reason why this is unsafe is that we are converting and
+  // unconditionally retaining, rather than before converting from
+  // unmanaged->ref checking that our value is not yet uninitialized.
   auto unmanagedType = originalValue.getType().getAs<UnmanagedStorageType>();
   SILValue result = SILBuilder::createUnmanagedToRef(
       loc, originalValue.getValue(),
       SILType::getPrimitiveObjectType(unmanagedType.getReferentType()));
-  SILBuilder::createUnmanagedRetainValue(loc, result, getDefaultAtomicity());
+  result = SILBuilder::createCopyValue(loc, result);
   return SGF.emitManagedRValueWithCleanup(result);
 }
 

test/SILGen/unmanaged_ownership.swift

@@ -0,0 +1,70 @@
+// RUN: %target-swift-frontend -enable-sil-ownership -parse-stdlib -module-name Swift -emit-silgen %s | %FileCheck %s
+
+class C {}
+
+enum Optional<T> {
+case none
+case some(T)
+}
+
+precedencegroup AssignmentPrecedence {
+  assignment: true
+  associativity: right
+}
+
+struct Holder {
+  unowned(unsafe) var value: C
+}
+
+_ = Holder(value: C())
+// CHECK-LABEL:sil hidden @_T0s6HolderV{{[_0-9a-zA-Z]*}}fC : $@convention(method) (@owned C, @thin Holder.Type) -> Holder
+// CHECK: bb0([[T0:%.*]] : @owned $C,
+// CHECK-NEXT:   [[T1:%.*]] = ref_to_unmanaged [[T0]] : $C to $@sil_unmanaged C
+// CHECK-NEXT:   destroy_value [[T0]] : $C
+// CHECK-NEXT:   [[T2:%.*]] = struct $Holder ([[T1]] : $@sil_unmanaged C)
+// CHECK-NEXT:   return [[T2]] : $Holder
+// CHECK-NEXT: } // end sil function '_T0s6HolderVABs1CC5value_tcfC'
+func set(holder holder: inout Holder) {
+  holder.value = C()
+}
+
+// CHECK-LABEL: sil hidden @_T0s3setys6HolderVz6holder_tF : $@convention(thin) (@inout Holder) -> () {
+// CHECK: bb0([[ADDR:%.*]] : @trivial $*Holder):
+// CHECK:        [[T0:%.*]] = function_ref @_T0s1CC{{[_0-9a-zA-Z]*}}fC
+// CHECK:        [[C:%.*]] = apply [[T0]](
+// CHECK-NEXT:   [[WRITE:%.*]] = begin_access [modify] [unknown] [[ADDR]] : $*Holder
+// CHECK-NEXT:   [[T0:%.*]] = struct_element_addr [[WRITE]] : $*Holder, #Holder.value
+// CHECK-NEXT:   [[T1:%.*]] = ref_to_unmanaged [[C]]
+// CHECK-NEXT:   assign [[T1]] to [[T0]]
+// CHECK-NEXT:   destroy_value [[C]]
+// CHECK-NEXT:   end_access [[WRITE]] : $*Holder
+// CHECK: } // end sil function '_T0s3setys6HolderVz6holder_tF'
+
+func get(holder holder: inout Holder) -> C {
+  return holder.value
+}
+// CHECK-LABEL: sil hidden @_T0s3gets1CCs6HolderVz6holder_tF : $@convention(thin) (@inout Holder) -> @owned C {
+// CHECK: bb0([[ADDR:%.*]] : @trivial $*Holder):
+// CHECK-NEXT:   debug_value_addr %0 : $*Holder, var, name "holder", argno 1 
+// CHECK-NEXT:   [[READ:%.*]] = begin_access [read] [unknown] [[ADDR]] : $*Holder
+// CHECK-NEXT:   [[T0:%.*]] = struct_element_addr [[READ]] : $*Holder, #Holder.value
+// CHECK-NEXT:   [[T1:%.*]] = load [trivial] [[T0]] : $*@sil_unmanaged C
+// CHECK-NEXT:   [[T2:%.*]] = unmanaged_to_ref [[T1]]
+// CHECK-NEXT:   [[T2_COPY:%.*]] = copy_value [[T2]]
+// CHECK-NEXT:   end_access [[READ]] : $*Holder
+// CHECK-NEXT:   return [[T2_COPY]]
+
+func project(fn fn: () -> Holder) -> C {
+  return fn().value
+}
+// CHECK-LABEL: sil hidden @_T0s7projects1CCs6HolderVyc2fn_tF : $@convention(thin) (@owned @callee_owned () -> Holder) -> @owned C {
+// CHECK: bb0([[FN:%.*]] : @owned $@callee_owned () -> Holder):
+// CHECK:      [[BORROWED_FN:%.*]] = begin_borrow [[FN]]
+// CHECK-NEXT: [[BORROWED_FN_COPY:%.*]] = copy_value [[BORROWED_FN]]
+// CHECK-NEXT: [[T0:%.*]] = apply [[BORROWED_FN_COPY]]()
+// CHECK-NEXT: [[T1:%.*]] = struct_extract [[T0]] : $Holder, #Holder.value
+// CHECK-NEXT: [[T2:%.*]] = unmanaged_to_ref [[T1]]
+// CHECK-NEXT: [[COPIED_T2:%.*]] = copy_value [[T2]]
+// CHECK-NEXT: end_borrow [[BORROWED_FN]] from [[FN]]
+// CHECK-NEXT: destroy_value [[FN]]
+// CHECK-NEXT: return [[COPIED_T2]]