[SILOptimizer] DI: Add a way to check whether TheMemory is _storage local var

Author: xedin

lib/SILOptimizer/Mandatory/DIMemoryUseCollector.cpp

@@ -538,6 +538,30 @@ ConstructorDecl *DIMemoryObjectInfo::getActorInitSelf() const {
   return nullptr;
 }
 
+VarDecl *DIMemoryObjectInfo::getAsTypeWrapperLocalStorageVar() const {
+  if (!MemoryInst->isVar())
+    return nullptr;
+
+  if (!isa<TupleType>(getASTType()))
+    return nullptr;
+
+  auto *DC = MemoryInst->getFunction()->getDeclContext();
+  if (!DC)
+    return nullptr;
+
+  auto *ctor = dyn_cast_or_null<ConstructorDecl>(DC->getAsDecl());
+  if (!ctor || ctor->isImplicit())
+    return nullptr;
+
+  if (auto *var = getLoc().getAsASTNode<VarDecl>()) {
+    auto &ctx = var->getASTContext();
+    if (var->isImplicit() && var->getName() == ctx.Id_localStorageVar)
+      return var;
+  }
+
+  return nullptr;
+}
+
 //===----------------------------------------------------------------------===//
 //                        DIMemoryUse Implementation
 //===----------------------------------------------------------------------===//

lib/SILOptimizer/Mandatory/DIMemoryUseCollector.h

@@ -164,6 +164,11 @@ class DIMemoryObjectInfo {
   /// actor's initializer. Otherwise, returns nullptr.
   ConstructorDecl *getActorInitSelf() const;
 
+  /// If \c TheMemory is a temporary variable that is responsible for
+  /// member-by-member initialization of `$Storage` in a user-defined
+  /// initializer of a type wrapped type, return its declaration.
+  VarDecl *getAsTypeWrapperLocalStorageVar() const;
+
   /// True if this memory object is the 'self' of a derived class initializer.
   bool isDerivedClassSelf() const { return MemoryInst->isDerivedClassSelf(); }