Merge pull request #78759 from swiftlang/gaborh/addressable-references

[cxx-interop] Mark C++ reference parameters @Addressable

Author: Xazax-hun

lib/ClangImporter/ImportDecl.cpp

@@ -3946,6 +3946,9 @@ namespace {
           }
           if (selfIdx) {
             func->setSelfIndex(selfIdx.value());
+            if (Impl.SwiftContext.LangOpts.hasFeature(
+                    Feature::AddressableParameters))
+              func->getImplicitSelfDecl()->setAddressable();
           } else {
             func->setStatic();
             func->setImportAsStaticMember();

lib/ClangImporter/ImportType.cpp

@@ -2676,17 +2676,25 @@ static ParamDecl *getParameterInfo(ClangImporter::Implementation *impl,
       impl->importSourceLoc(param->getLocation()), bodyName,
       impl->ImportedHeaderUnit);
 
+  auto &ASTContext = paramInfo->getASTContext();
   // If SendingArgsAndResults are enabled and we have a sending argument,
   // set that the param was sending.
-  if (paramInfo->getASTContext().LangOpts.hasFeature(
-          Feature::SendingArgsAndResults)) {
+  if (ASTContext.LangOpts.hasFeature(Feature::SendingArgsAndResults)) {
     if (auto *attr = param->getAttr<clang::SwiftAttrAttr>()) {
       if (attr->getAttribute() == "sending") {
         paramInfo->setSending();
       }
     }
   }
 
+  // C++ types taking a reference might return a reference/pointer to a
+  // subobject of the referenced storage. In those cases we need to prevent the
+  // Swift compiler to pass in a temporary copy to prevent dangling.
+  if (ASTContext.LangOpts.hasFeature(Feature::AddressableParameters) &&
+      !param->getType().isNull() && param->getType()->isReferenceType()) {
+    paramInfo->setAddressable();
+  }
+
   // Parameters of type const T& imported as T, make sure we borrow from them
   // when they have lifetime annotations.
   bool isBorrowing = (param->getAttr<clang::LifetimeBoundAttr>() ||

test/Interop/Cxx/class/method/Inputs/methods.h

@@ -33,6 +33,9 @@ struct HasMethods {
 
   NonTrivialInWrapper nonConstPassThroughAsWrapper(int a) { return {a}; }
   NonTrivialInWrapper constPassThroughAsWrapper(int a) const { return {a}; }
+
+  void nonTrivialTakesConstRef(const NonTrivialInWrapper& w) const {}
+  void nonTrivialTakesRef(NonTrivialInWrapper& w) const {}
 };
 
 struct ReferenceParams {

test/Interop/Cxx/class/method/methods-addressable-silgen.swift

@@ -0,0 +1,23 @@
+
+// RUN: %target-swift-emit-silgen -I %S/Inputs -enable-experimental-feature AddressableParameters -enable-experimental-cxx-interop %s | %FileCheck %s
+
+import Methods
+
+// REQUIRES: swift_feature_AddressableParameters
+
+public func addressableTest(x: borrowing @_addressable NonTrivialInWrapper, y: inout NonTrivialInWrapper) {
+  let m = HasMethods()
+  m.nonTrivialTakesConstRef(x)
+  // No copy from the argument to the apply.
+  // CHECK: addressableTest(x:y:)
+  // CHECK: bb0([[INPUT:%[0-9]+]] : @noImplicitCopy $*NonTrivialInWrapper, [[INPUT2:%[0-9]+]] : $*NonTrivialInWrapper)
+  // CHECK: [[WRAPPER:%[0-9]+]] = copyable_to_moveonlywrapper_addr [[INPUT]]
+  // CHECK: [[MARKED:%[0-9]+]] = mark_unresolved_non_copyable_value [no_consume_or_assign] [[WRAPPER]]
+  // CHECK: [[UNWRAPPED:%[0-9]+]] = moveonlywrapper_to_copyable_addr [[MARKED]]
+  // CHECK: %{{[0-9]+}} = apply %{{[0-9]+}}([[UNWRAPPED]], %{{[0-9]+}}) : $@convention(cxx_method) (@in_guaranteed NonTrivialInWrapper, @in_guaranteed HasMethods) -> ()
+  var m2 = HasMethods()
+  // CHECK: [[ACCESS:%[0-9]+]] = begin_access [modify] [unknown] [[INPUT2]]
+  // CHECK: %{{[0-9]+}} = apply %32([[ACCESS]], %{{[0-9]+}}) : $@convention(cxx_method) (@inout NonTrivialInWrapper, @in_guaranteed HasMethods) -> ()
+  // CHECK-NEXT: end_access [[ACCESS]]
+  m2.nonTrivialTakesRef(&y)
+}

test/Interop/Cxx/class/nonescapable-lifetimebound.swift

@@ -3,6 +3,7 @@
 // RUN: %target-swift-frontend -I %swift_src_root/lib/ClangImporter/SwiftBridging  -I %t/Inputs -emit-sil %t/test.swift -enable-experimental-feature LifetimeDependence -cxx-interoperability-mode=default -diagnostic-style llvm 2>&1 | %FileCheck %s
 // RUN: not %target-swift-frontend -I %swift_src_root/lib/ClangImporter/SwiftBridging  -I %t/Inputs -emit-sil %t/test.swift -cxx-interoperability-mode=default -diagnostic-style llvm 2>&1 | %FileCheck %s -check-prefix=CHECK-NO-LIFETIMES
 
+// REQUIRES: swift_feature_LifetimeDependence
 
 //--- Inputs/module.modulemap
 module Test {