[Runtime] Remove a few uses of operator new/delete.

Replace them with swift_cxx_newObject/swift_cxx_deleteObject to avoid calling overridden global operators. Overridden global operators can sometimes fail when called from places the authors didn't expect.

The particular uses being changed here are:

1. Creation of new SingletonMetadataCacheEntry objects.
2. Allocation of the _globalIvarOffsets array in initGenericObjCClass.
3. Creation/destruction of SwiftTLSContext objects.

rdar://106238547

Author: mikeash

stdlib/public/runtime/Metadata.cpp

@@ -1023,8 +1023,8 @@ namespace {
       // If there isn't one there, optimistically create an entry and
       // try to swap it in.
       if (!existingEntry) {
-        auto allocatedEntry =
-          new SingletonMetadataCacheEntry(std::forward<ArgTys>(args)...);
+        auto allocatedEntry = swift_cxx_newObject<SingletonMetadataCacheEntry>(
+            std::forward<ArgTys>(args)...);
         if (cache.Private.compare_exchange_strong(existingEntry,
                                                   allocatedEntry,
                                                   std::memory_order_acq_rel,
@@ -3303,12 +3303,12 @@ initGenericObjCClass(ClassMetadata *self, size_t numFields,
     if (!_globalIvarOffsets) {
       if (numFields <= NumInlineGlobalIvarOffsets) {
         _globalIvarOffsets = _inlineGlobalIvarOffsets;
+        // Make sure all the entries start out null.
+        memset(_globalIvarOffsets, 0, sizeof(size_t *) * numFields);
       } else {
-        _globalIvarOffsets = new size_t*[numFields];
+        _globalIvarOffsets =
+            static_cast<size_t **>(calloc(sizeof(size_t *), numFields));
       }
-
-      // Make sure all the entries start out null.
-      memset(_globalIvarOffsets, 0, sizeof(size_t*) * numFields);
     }
     return _globalIvarOffsets;
   };
@@ -3368,7 +3368,7 @@ initGenericObjCClass(ClassMetadata *self, size_t numFields,
 
     // Free the out-of-line if we allocated one.
     if (_globalIvarOffsets != _inlineGlobalIvarOffsets) {
-      delete [] _globalIvarOffsets;
+      free(_globalIvarOffsets);
     }
   }
 

stdlib/public/runtime/SwiftTLSContext.cpp

@@ -30,10 +30,10 @@ SwiftTLSContext &SwiftTLSContext::get() {
 
   static swift::once_t token;
   swift::tls_init_once(token, swift::tls_key::runtime, [](void *pointer) {
-    delete static_cast<SwiftTLSContext *>(pointer);
+    swift_cxx_deleteObject(static_cast<SwiftTLSContext *>(pointer));
   });
 
-  ctx = new SwiftTLSContext();
+  ctx = swift_cxx_newObject<SwiftTLSContext>();
   swift::tls_set(swift::tls_key::runtime, ctx);
   return *ctx;
 
@@ -51,15 +51,15 @@ SwiftTLSContext &SwiftTLSContext::get() {
   static swift::once_t token;
 
   swift::tls_alloc_once(token, runtimeKey, [](void *pointer) {
-    delete static_cast<SwiftTLSContext *>(pointer);
+    swift_cxx_deleteObject(static_cast<SwiftTLSContext *>(pointer));
   });
 
   SwiftTLSContext *ctx =
       static_cast<SwiftTLSContext *>(swift::tls_get(runtimeKey));
   if (ctx)
     return *ctx;
 
-  ctx = new SwiftTLSContext();
+  ctx = swift_cxx_newObject<SwiftTLSContext>();
   swift::tls_set(runtimeKey, ctx);
   return *ctx;