Merge pull request #58459 from grynspan/jgrynspan/avoid-operator-new-for-sidetables

Sidetables should not use `operator new` or `operator delete`.

Author: grynspan

include/swift/Runtime/Heap.h

@@ -20,13 +20,72 @@
 #include <cstddef>
 #include <cstdint>
 #include <cstdlib>
+#include <new>
 #include <type_traits>
+#include <utility>
+
+#include "swift/Runtime/Config.h"
 
 #if defined(_WIN32)
 #include <malloc.h>
 #endif
 
 namespace swift {
+// Allocate plain old memory. This is the generalized entry point
+// Never returns nil. The returned memory is uninitialized. 
+//
+// An "alignment mask" is just the alignment (a power of 2) minus 1.
+SWIFT_RUNTIME_EXPORT
+void *swift_slowAlloc(size_t bytes, size_t alignMask);
+
+// If the caller cannot promise to zero the object during destruction,
+// then call these corresponding APIs:
+SWIFT_RUNTIME_EXPORT
+void swift_slowDealloc(void *ptr, size_t bytes, size_t alignMask);
+
+/// Allocate and construct an instance of type \c T.
+///
+/// \param args The arguments to pass to the constructor for \c T.
+///
+/// \returns A pointer to a new, fully constructed instance of \c T. This
+///   function never returns \c nullptr. The caller is responsible for
+///   eventually destroying the resulting object by passing it to
+///   \c swift_cxx_deleteObject().
+///
+/// This function avoids the use of the global \c operator \c new (which may be
+/// overridden by other code in a process) in favor of calling
+/// \c swift_slowAlloc() and constructing the new object with placement new.
+///
+/// This function is capable of returning well-aligned memory even on platforms
+/// that do not implement the C++17 "over-aligned new" feature.
+template <typename T, typename... Args>
+static inline T *swift_cxx_newObject(Args &&... args) {
+  auto result = reinterpret_cast<T *>(swift_slowAlloc(sizeof(T),
+                                                      alignof(T) - 1));
+  ::new (result) T(std::forward<Args>(args)...);
+  return result;
+}
+
+/// Destruct and deallocate an instance of type \c T.
+///
+/// \param ptr A pointer to an instance of type \c T previously created with a
+///   call to \c swift_cxx_newObject().
+///
+/// This function avoids the use of the global \c operator \c delete (which may
+/// be overridden by other code in a process) in favor of directly calling the
+/// destructor for \a *ptr and then freeing its memory by calling
+/// \c swift_slowDealloc().
+///
+/// The effect of passing a pointer to this function that was \em not returned
+/// from \c swift_cxx_newObject() is undefined.
+template <typename T>
+static inline void swift_cxx_deleteObject(T *ptr) {
+  if (ptr) {
+    ptr->~T();
+    swift_slowDealloc(ptr, sizeof(T), alignof(T) - 1);
+  }
+}
+
 namespace {
 // This is C++17 and newer, so we simply re-define it.  Since the codebase is
 // C++14, assume that DR1558 is accounted for and that unused parameters in alias

include/swift/Runtime/HeapObject.h

@@ -19,8 +19,6 @@
 
 #include <cstddef>
 #include <cstdint>
-#include <new>
-#include <utility>
 #include "swift/Runtime/Config.h"
 
 #if SWIFT_OBJC_INTEROP
@@ -120,62 +118,6 @@ BoxPair swift_makeBoxUnique(OpaqueValue *buffer, Metadata const *type,
 SWIFT_RUNTIME_EXPORT
 HeapObject* swift_allocEmptyBox();
 
-// Allocate plain old memory. This is the generalized entry point
-// Never returns nil. The returned memory is uninitialized. 
-//
-// An "alignment mask" is just the alignment (a power of 2) minus 1.
-
-SWIFT_RUNTIME_EXPORT
-void *swift_slowAlloc(size_t bytes, size_t alignMask);
-
-// If the caller cannot promise to zero the object during destruction,
-// then call these corresponding APIs:
-SWIFT_RUNTIME_EXPORT
-void swift_slowDealloc(void *ptr, size_t bytes, size_t alignMask);
-
-/// Allocate and construct an instance of type \c T.
-///
-/// \param args The arguments to pass to the constructor for \c T.
-///
-/// \returns A pointer to a new, fully constructed instance of \c T. This
-///   function never returns \c nullptr. The caller is responsible for
-///   eventually destroying the resulting object by passing it to
-///   \c swift_cxx_deleteObject().
-///
-/// This function avoids the use of the global \c operator \c new (which may be
-/// overridden by other code in a process) in favor of calling
-/// \c swift_slowAlloc() and constructing the new object with placement new.
-///
-/// This function is capable of returning well-aligned memory even on platforms
-/// that do not implement the C++17 "over-aligned new" feature.
-template <typename T, typename... Args>
-static inline T *swift_cxx_newObject(Args &&... args) {
-  auto result = reinterpret_cast<T *>(swift_slowAlloc(sizeof(T),
-                                                      alignof(T) - 1));
-  ::new (result) T(std::forward<Args>(args)...);
-  return result;
-}
-
-/// Destruct and deallocate an instance of type \c T.
-///
-/// \param ptr A pointer to an instance of type \c T previously created with a
-///   call to \c swift_cxx_newObject().
-///
-/// This function avoids the use of the global \c operator \c delete (which may
-/// be overridden by other code in a process) in favor of directly calling the
-/// destructor for \a *ptr and then freeing its memory by calling
-/// \c swift_slowDealloc().
-///
-/// The effect of passing a pointer to this function that was \em not returned
-/// from \c swift_cxx_newObject() is undefined.
-template <typename T>
-static inline void swift_cxx_deleteObject(T *ptr) {
-  if (ptr) {
-    ptr->~T();
-    swift_slowDealloc(ptr, sizeof(T), alignof(T) - 1);
-  }
-}
-
 /// Atomically increments the retain count of an object.
 ///
 /// \param object - may be null, in which case this is a no-op

stdlib/public/SwiftShims/RefCount.h

@@ -1329,6 +1329,9 @@ class HeapObjectSideTableEntry {
 #endif
   { }
 
+  void *operator new(size_t) = delete;
+  void operator delete(void *) = delete;
+
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Winvalid-offsetof"
   static ptrdiff_t refCountsOffset() {
@@ -1455,7 +1458,7 @@ class HeapObjectSideTableEntry {
     // Weak ref count is now zero. Delete the side table entry.
     // FREED -> DEAD
     assert(refCounts.getUnownedCount() == 0);
-    delete this;
+    swift_cxx_deleteObject(this);
   }
 
   void decrementWeakNonAtomic() {
@@ -1468,7 +1471,7 @@ class HeapObjectSideTableEntry {
     // Weak ref count is now zero. Delete the side table entry.
     // FREED -> DEAD
     assert(refCounts.getUnownedCount() == 0);
-    delete this;
+    swift_cxx_deleteObject(this);
   }
 
   uint32_t getWeakCount() const {

stdlib/public/runtime/RefCount.cpp

@@ -97,7 +97,7 @@ HeapObjectSideTableEntry* RefCounts<InlineRefCountBits>::allocateSideTable(bool
   // Preflight passed. Allocate a side table.
 
   // FIXME: custom side table allocator
-  HeapObjectSideTableEntry *side = new HeapObjectSideTableEntry(getHeapObject());
+  auto side = swift_cxx_newObject<HeapObjectSideTableEntry>(getHeapObject());
 
   auto newbits = InlineRefCountBits(side);
 
@@ -106,7 +106,7 @@ HeapObjectSideTableEntry* RefCounts<InlineRefCountBits>::allocateSideTable(bool
       // Already have a side table. Return it and delete ours.
       // Read before delete to streamline barriers.
       auto result = oldbits.getSideTable();
-      delete side;
+      swift_cxx_deleteObject(side);
       return result;
     }
     else if (failIfDeiniting && oldbits.getIsDeiniting()) {