IRGen: correct some type deletion

ASAN identified mismatched `operator new` and `operator delete` on these
types. The reason for this is the sized allocation for the tail packing
involved. Provide the associated `operator delete` that releases the
memory. Note that the `operator delete` is static and does not have the
implicit `this` pointer, and we cannot use the name `this` for the
variable.

Author: compnerd

lib/IRGen/GenExistential.cpp

@@ -130,6 +130,7 @@ namespace {
   class ExistentialTypeInfoBase : public Base,
       private llvm::TrailingObjects<Derived, const ProtocolDecl *> {
     friend class llvm::TrailingObjects<Derived, const ProtocolDecl *>;
+    using Tail = llvm::TrailingObjects<Derived, const ProtocolDecl *>;
 
     /// The number of non-trivial protocols for this existential.
     unsigned NumStoredProtocols;
@@ -157,12 +158,19 @@ namespace {
     create(ArrayRef<const ProtocolDecl *> protocols, As &&...args)
     {
       void *buffer = operator new(
-          llvm::TrailingObjects<Derived, const ProtocolDecl *>::
-              template totalSizeToAlloc<const ProtocolDecl *>(
-                  protocols.size()));
+          Tail::template totalSizeToAlloc<const ProtocolDecl *>(
+              protocols.size()));
       return new (buffer) Derived(protocols, std::forward<As>(args)...);
     }
 
+    void operator delete(void *ptr) {
+      const auto *pThis = static_cast<ExistentialTypeInfoBase *>(ptr);
+      const size_t count = pThis->NumStoredProtocols;
+      const size_t size =
+          Tail::template totalSizeToAlloc<const ProtocolDecl *>(count);
+      ::operator delete(ptr, size);
+    }
+
     /// Returns the number of protocol witness tables directly carried
     /// by values of this type.
     unsigned getNumStoredProtocols() const { return NumStoredProtocols; }

lib/IRGen/GenRecord.h

@@ -157,6 +157,13 @@ class RecordTypeInfoImpl : public Base,
     return new(buffer) Impl(fields, std::forward<As>(args)...);
   }
 
+  void operator delete(void *ptr) {
+    const auto *pThis = static_cast<RecordTypeInfoImpl *>(ptr);
+    const size_t count = pThis->NumFields;
+    const size_t size = Impl::template totalSizeToAlloc<FieldImpl>(count);
+    ::operator delete(ptr, size);
+  }
+
   bool areFieldsABIAccessible() const {
     return AreFieldsABIAccessible;
   }

lib/IRGen/ProtocolInfo.h

@@ -230,6 +230,13 @@ class ProtocolInfo final :
                                               ProtocolInfoKind kind);
 
 public:
+  void operator delete(void *ptr) {
+    const auto *pThis = static_cast<ProtocolInfo *>(ptr);
+    const size_t count = pThis->NumTableEntries;
+    const size_t size = totalSizeToAlloc<WitnessTableEntry>(count);
+    ::operator delete(ptr, size);
+  }
+
   /// The number of witness slots in a conformance to this protocol;
   /// in other words, the size of the table in words.
   unsigned getNumWitnesses() const {