[interop][SwiftToCxx] ensure that buffers for heap allocated Swift values are released after parameter copy is consumed

Author: hyp

lib/PrintAsClang/_SwiftCxxInteroperability.h

@@ -110,6 +110,12 @@ extern "C" void _fatalError_Cxx_move_of_Swift_value_type_not_supported_yet();
 
 SWIFT_INLINE_THUNK void *_Nonnull opaqueAlloc(size_t size,
                                               size_t align) noexcept {
+#if defined(SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_alloc) &&       \
+    defined(SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_free)
+  // Allow the user to provide custom allocator for heap-allocated Swift
+  // value types.
+  return SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_alloc(size, align);
+#else
 #if defined(_WIN32)
   void *r = _aligned_malloc(size, align);
 #else
@@ -120,14 +126,22 @@ SWIFT_INLINE_THUNK void *_Nonnull opaqueAlloc(size_t size,
   (void)res;
 #endif
   return r;
+#endif
 }
 
 SWIFT_INLINE_THUNK void opaqueFree(void *_Nonnull p) noexcept {
+#if defined(SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_alloc) &&       \
+    defined(SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_free)
+  // Allow the user to provide custom allocator for heap-allocated Swift
+  // value types.
+  SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_free(p);
+#else
 #if defined(_WIN32)
   _aligned_free(p);
 #else
   free(p);
 #endif
+#endif
 }
 
 /// Base class for a container for an opaque Swift value, like resilient struct.

test/Interop/SwiftToCxx/ownership/consuming-parameter-in-cxx-execution.cpp

@@ -11,6 +11,24 @@
 // REQUIRES: executable_test
 
 #include <assert.h>
+#include <stdint.h>
+
+size_t allocCount = 0;
+size_t totalAllocs = 0;
+
+void * _Nonnull trackedAlloc(size_t size, size_t align) {
+    ++allocCount;
+    ++totalAllocs;
+    return malloc(size);
+}
+void trackedFree(void *_Nonnull p) {
+    --allocCount;
+    free(p);
+}
+
+#define SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_alloc trackedAlloc
+#define SWIFT_CXX_INTEROPERABILITY_OVERRIDE_OPAQUE_STORAGE_free  trackedFree
+
 #include "consuming.h"
 
 extern "C" size_t swift_retainCount(void * _Nonnull obj);
@@ -45,5 +63,8 @@ int main() {
     assert(getRetainCount(k) == 3);
   }
 // CHECK-NEXT: destroy AKlass
+  // verify that all of the opaque buffers are freed.
+  assert(allocCount == 0);
+  assert(totalAllocs != 0);
   return 0;
 }

test/Interop/SwiftToCxx/ownership/resilient-consuming-parameter-in-cxx-execution.cpp

@@ -0,0 +1,11 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend %S/consuming-parameter-in-cxx.swift -typecheck -module-name Init -clang-header-expose-decls=all-public -emit-clang-header-path %t/consuming.h -enable-library-evolution
+
+// RUN: %target-interop-build-clangxx -c %S/consuming-parameter-in-cxx-execution.cpp -I %t -o %t/swift-consume-execution.o
+// RUN: %target-interop-build-swift %S/consuming-parameter-in-cxx.swift -o %t/swift-consume-execution-evo -Xlinker %t/swift-consume-execution.o -module-name Init -Xfrontend -entry-point-function-name -Xfrontend swiftMain -enable-library-evolution
+
+// RUN: %target-codesign %t/swift-consume-execution-evo
+// RUN: %target-run %t/swift-consume-execution-evo | %FileCheck %S/consuming-parameter-in-cxx-execution.cpp
+
+// REQUIRES: executable_test