[OpaqueValues] Emit unowned copies.

In opaque values mode, emit the unowned copy instructions to convert as
follows:

strong_copy_unowned_value: `@owned $sil_unowned T` -> `@owned $T`
unowned_copy_value: `@owned T` -> `@owned $sil_unowned T`

Doing so is necessary in opaque values mode where it is needed to deal
with unowned values directly rather than indirectly via `load_unowned`s
and `store_unowned`s.

Author: nate-chandler

lib/SILGen/SILGenBuilder.cpp

@@ -191,7 +191,8 @@ ManagedValue SILGenBuilder::createCopyValue(SILLocation loc,
   ManagedValue SILGenBuilder::createStrongCopy##Name##Value(                   \
       SILLocation loc, ManagedValue originalValue) {                           \
     auto ty = originalValue.getType().castTo<Name##StorageType>();             \
-    assert(ty->isLoadable(ResilienceExpansion::Maximal));                      \
+    assert(ty->isLoadable(ResilienceExpansion::Maximal) ||                     \
+           !SGF.useLoweredAddresses());                                        \
     (void)ty;                                                                  \
     SILValue result =                                                          \
         createStrongCopy##Name##Value(loc, originalValue.getValue());          \

lib/SILGen/SILGenLValue.cpp

@@ -4847,8 +4847,11 @@ SILValue SILGenFunction::emitConversionFromSemanticValue(SILLocation loc,
         B.emitDestroyValueOperation(loc, semanticValue);
         return value;
       }
-      case ReferenceOwnership::Unowned:
-        llvm_unreachable("unimplemented");
+      case ReferenceOwnership::Unowned: {
+        auto value = B.createUnownedCopyValue(loc, semanticValue);
+        B.emitDestroyValueOperation(loc, semanticValue);
+        return value;
+      }
     }
   }
   switch (swiftStorageType->getOwnership()) {
@@ -4864,16 +4867,16 @@ SILValue SILGenFunction::emitConversionFromSemanticValue(SILLocation loc,
     B.emitDestroyValueOperation(loc, semanticValue); \
     return value; \
   }
-#define SOMETIMES_LOADABLE_CHECKED_REF_STORAGE(Name, ...) \
-  case ReferenceOwnership::Name: { \
-    /* For loadable types, place into a box. */ \
-    auto type = storageType.castTo<Name##StorageType>(); \
-    assert(type->isLoadable(ResilienceExpansion::Maximal)); \
-    (void) type; \
-    SILValue value = B.createRefTo##Name(loc, semanticValue, storageType); \
-    value = B.createCopyValue(loc, value); \
-    B.emitDestroyValueOperation(loc, semanticValue); \
-    return value; \
+#define SOMETIMES_LOADABLE_CHECKED_REF_STORAGE(Name, ...)                      \
+  case ReferenceOwnership::Name: {                                             \
+    /* For loadable types, place into a box. */                                \
+    auto type = storageType.castTo<Name##StorageType>();                       \
+    assert(type->isLoadable(ResilienceExpansion::Maximal));                    \
+    (void)type;                                                                \
+    SILValue value = B.createRefTo##Name(loc, semanticValue, storageType);     \
+    value = B.createCopyValue(loc, value);                                     \
+    B.emitDestroyValueOperation(loc, semanticValue);                           \
+    return value;                                                              \
   }
 #define UNCHECKED_REF_STORAGE(Name, ...) \
   case ReferenceOwnership::Name: { \

test/SILGen/opaque_values_silgen_nonobjc.swift

@@ -0,0 +1,25 @@
+// RUN: %target-swift-emit-silgen -enable-sil-opaque-values -Xllvm -sil-full-demangle -disable-objc-interop -primary-file %s | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-runtime
+
+// Test SILGen -enable-sil-opaque-values with tests that depend on the stdlib and objc interop.
+
+// REQUIRES: objc_interop
+
+// CHECK-LABEL: sil {{.*}}[ossa] @$s28opaque_values_silgen_nonobjc13UnownedVarBoxV5valuexvg : {{.*}} {
+// CHECK:       bb0([[INSTANCE:%[^,]+]] :
+// CHECK:         [[UNOWNED_VALUE:%[^,]+]] = struct_extract [[INSTANCE]]
+// CHECK:         [[STRONG_VALUE:%[^,]+]] = strong_copy_unowned_value [[UNOWNED_VALUE]]
+// CHECK:         return [[STRONG_VALUE]]
+// CHECK-LABEL: } // end sil function '$s28opaque_values_silgen_nonobjc13UnownedVarBoxV5valuexvg'
+// CHECK-LABEL: sil {{.*}}[ossa] @$s28opaque_values_silgen_nonobjc13UnownedVarBoxV5valueACyxGx_tcfC : {{.*}} {
+// CHECK:       bb0([[STRONG_VALUE:%[^,]+]] :
+// CHECK:         [[WRAPPED_IN_UNOWNED_TYPE:%[^,]+]] = ref_to_unowned [[STRONG_VALUE]]
+// CHECK:         [[UNOWNED_VALUE:%[^,]+]] = copy_value [[WRAPPED_IN_UNOWNED_TYPE]]
+// CHECK:         destroy_value [[STRONG_VALUE]]
+// CHECK:         [[RETVAL:%[^,]+]] = struct $UnownedVarBox<T> ([[UNOWNED_VALUE]] : $@sil_unowned T)
+// CHECK:         return [[RETVAL]]
+// CHECK-LABEL: } // end sil function '$s28opaque_values_silgen_nonobjc13UnownedVarBoxV5valueACyxGx_tcfC'
+struct UnownedVarBox<T : AnyObject> {
+  unowned var value: T
+}
+
+

test/SILGen/opaque_values_silgen_objc.swift

@@ -0,0 +1,23 @@
+// RUN: %target-swift-emit-silgen -enable-sil-opaque-values -Xllvm -sil-full-demangle -primary-file %s | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-runtime
+
+// Test SILGen -enable-sil-opaque-values with tests that depend on the stdlib and objc interop.
+
+// REQUIRES: objc_interop
+
+// CHECK-LABEL: sil {{.*}}[ossa] @$s25opaque_values_silgen_objc10UnownedBoxV5valuexvg : {{.*}} {
+// CHECK:       bb0([[INSTANCE:%[^,]+]] :
+// CHECK:         [[UNOWNED_VALUE:%[^,]+]] = struct_extract [[INSTANCE]]
+// CHECK:         [[STRONG_VALUE:%[^,]+]] = strong_copy_unowned_value [[UNOWNED_VALUE]]
+// CHECK:         return [[STRONG_VALUE]]
+// CHECK-LABEL: } // end sil function '$s25opaque_values_silgen_objc10UnownedBoxV5valuexvg'
+// CHECK-LABEL: sil {{.*}}[ossa] @$s25opaque_values_silgen_objc10UnownedBoxV5valueACyxGx_tcfC : {{.*}} {
+// CHECK:       bb0([[STRONG_VALUE:%[^,]+]] :
+// CHECK:         [[UNOWNED_VALUE:%[^,]+]] = unowned_copy_value [[STRONG_VALUE]]
+// CHECK:         destroy_value [[STRONG_VALUE]]
+// CHECK:         [[RETVAL:%[^,]+]] = struct $UnownedBox<T> ([[UNOWNED_VALUE]] : $@sil_unowned T)
+// CHECK:         return [[RETVAL]]
+// CHECK-LABEL: } // end sil function '$s25opaque_values_silgen_objc10UnownedBoxV5valueACyxGx_tcfC'
+struct UnownedBox<T : AnyObject> {
+  unowned var value: T
+}
+