Bug 1297801 - part 1 - commonize the managee->array functions in IPDL…

… generated code; r=billm

There's no reason to generate identical code for every kind of managed
protocol; we can have a single instance that operates on void* and cast
our way to victory.  This change saves ~60K of text on x86-64 Linux.

ipc/glue/ProtocolUtils.cpp

@@ -464,5 +464,17 @@ void ArrayLengthReadError(const char* aElementName)
   NS_RUNTIMEABORT(message.get());
 }
 
+void
+TableToArray(const nsTHashtable<nsPtrHashKey<void>>& aTable,
+             nsTArray<void*>& aArray)
+{
+  uint32_t i = 0;
+  void** elements = aArray.AppendElements(aTable.Count());
+  for (auto iter = aTable.ConstIter(); !iter.Done(); iter.Next()) {
+    elements[i] = iter.Get()->GetKey();
+    ++i;
+  }
+}
+
 } // namespace ipc
 } // namespace mozilla

ipc/glue/ProtocolUtils.h

@@ -1,4 +1,4 @@
-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  * vim: sw=4 ts=4 et :
  */
 /* This Source Code Form is subject to the terms of the Mozilla Public
@@ -604,10 +604,31 @@ CreateEndpoints(const PrivateIPDLInterface& aPrivate,
   return NS_OK;
 }
 
+void
+TableToArray(const nsTHashtable<nsPtrHashKey<void>>& aTable,
+             nsTArray<void*>& aArray);
+
 } // namespace ipc
 
 template<typename Protocol>
-using ManagedContainer = nsTHashtable<nsPtrHashKey<Protocol>>;
+class ManagedContainer : public nsTHashtable<nsPtrHashKey<Protocol>>
+{
+  typedef nsTHashtable<nsPtrHashKey<Protocol>> BaseClass;
+
+public:
+  // Having the core logic work on void pointers, rather than typed pointers,
+  // means that we can have one instance of this code out-of-line, rather
+  // than several hundred instances of this code out-of-lined.  (Those
+  // repeated instances don't necessarily get folded together by the linker
+  // because they contain member offsets and such that differ between the
+  // functions.)  We do have to pay for it with some eye-bleedingly bad casts,
+  // though.
+  void ToArray(nsTArray<Protocol*>& aArray) const {
+    ::mozilla::ipc::TableToArray(*reinterpret_cast<const nsTHashtable<nsPtrHashKey<void>>*>
+                                 (static_cast<const BaseClass*>(this)),
+                                 reinterpret_cast<nsTArray<void*>&>(aArray));
+  }
+};
 
 template<typename Protocol>
 Protocol*

ipc/ipdl/ipdl/lower.py

@@ -3086,22 +3086,10 @@ def forLoopOverHashtable(hashtable, itervar, const=False):
                 params=[ Decl(_cxxArrayType(p.managedCxxType(managed, self.side), ref=1),
                               arrvar.name) ],
                 const=1))
-            ivar = ExprVar('i')
-            elementsvar = ExprVar('elements')
-            itervar = ExprVar('iter')
-            meth.addstmt(StmtDecl(Decl(Type.UINT32, ivar.name),
-                                  init=ExprLiteral.ZERO))
-            meth.addstmt(StmtDecl(Decl(Type(_actorName(managed.name(), self.side), ptrptr=1), elementsvar.name),
-                                  init=ExprCall(ExprSelect(arrvar, '.', 'AppendElements'),
-                                                args=[ ExprCall(ExprSelect(p.managedVar(managed, self.side),
-                                                                           '.', 'Count')) ])))
-            foreachaccumulate = forLoopOverHashtable(p.managedVar(managed, self.side),
-                                                     itervar, const=True)
-            foreachaccumulate.addstmt(StmtExpr(
-                ExprAssn(ExprIndex(elementsvar, ivar),
-                         actorFromIter(itervar))))
-            foreachaccumulate.addstmt(StmtExpr(ExprPrefixUnop(ivar, '++')))
-            meth.addstmt(foreachaccumulate)
+            meth.addstmt(StmtExpr(
+                ExprCall(ExprSelect(p.managedVar(managed, self.side),
+                                    '.', 'ToArray'),
+                         args=[ arrvar ])))
 
             refmeth = MethodDefn(MethodDecl(
                 p.managedMethod(managed, self.side).name,