Bug 1196634 - Part 4: Remove JS::ubi::Node::getCanonicalTypeName; r=sfink

js/public/UbiNode.h

@@ -699,10 +699,6 @@ class Node {
     template<typename T>
     static const char16_t* canonicalTypeName() { return Concrete<T>::concreteTypeName; }
 
-    // Get the canonical type name for the supplied string, if one
-    // exists. Otherwise nullptr is returned.
-    static const char16_t* getCanonicalTypeName(const char16_t* dupe, size_t length);
-
     template<typename T>
     bool is() const {
         return base()->typeName() == canonicalTypeName<T>();

js/src/vm/UbiNode.cpp

@@ -144,134 +144,6 @@ StackFrame::functionDisplayNameLength()
     return functionDisplayName().match(m);
 }
 
-/* static */ const char16_t*
-Node::getCanonicalTypeName(const char16_t* dupe, size_t length)
-{
-    // This function is a hot mess of practicality.
-    //
-    // JS::ubi::Node::is<T> uses pointer identity to T's canonical type name
-    // string to determine type equivalence because (a) we don't have RTTI, and
-    // (b) a JS::ubi::Node instance backed by an offline heap snapshot wants
-    // is<JSScript>() to be true if that node represents a JSScript that was
-    // live when the heap snapshot was taken, but obviously there isn't a live
-    // JSScript backing it anymore. So, we need to be able to get a pointer to
-    // T's canonical type name string if we want is<T>() to work properly with
-    // nodes backed by an offline heap snapshot.
-    //
-    // Enter JS::ubi::Node::getCanonicalTypeName, stage right.
-    //
-    // Ideally, this function would return a pointer to the canonical
-    // Concrete<T>::concreteTypeName string that is structurally identical to
-    // the given in dupe string for all Concrete<T> specializations. In a
-    // perfect world, we could use static constructors in Firefox and
-    // SpiderMonkey and build up a registry of canonical type names at
-    // compile/link time. This is not the world we live in. We observe that
-    // while the set of concrete JS::ubi::Node specializations is open ended,
-    // there is a finite set of Ts passed to is<T>() in our various
-    // JS::ubi::Node analyses and we only really need is<T>() to work for
-    // them. That set is hard coded here.
-    //
-    // Uh... static_assert(grep for is<T>() calls and we got them all), right?
-    // Hold me and tell me it will be ok? Please?
-    //
-    // Oh and to top it off, this function is pretty hot: it's called for every
-    // single node we deserialize in a heap snapshot, and there tend to be a lot
-    // of those.
-
-    MOZ_ASSERT(8 == strlen("JSObject") &&
-               8 == strlen("JSScript") &&
-               8 == strlen("JSString"));
-    if (length == 8) {
-        if (dupe[0] == 'J' &&
-            dupe[1] == 'S' &&
-            dupe[2] == 'O' &&
-            dupe[3] == 'b' &&
-            dupe[4] == 'j' &&
-            dupe[5] == 'e' &&
-            dupe[6] == 'c' &&
-            dupe[7] == 't')
-        {
-            return JS::ubi::Node::canonicalTypeName<JSObject>();
-        }
-
-        if (dupe[0] == 'J' &&
-            dupe[1] == 'S' &&
-            dupe[2] == 'S' &&
-            dupe[3] == 'c' &&
-            dupe[4] == 'r' &&
-            dupe[5] == 'i' &&
-            dupe[6] == 'p' &&
-            dupe[7] == 't')
-        {
-            return JS::ubi::Node::canonicalTypeName<JSScript>();
-        }
-
-        if (dupe[0] == 'J' &&
-            dupe[1] == 'S' &&
-            dupe[2] == 'S' &&
-            dupe[3] == 't' &&
-            dupe[4] == 'r' &&
-            dupe[5] == 'i' &&
-            dupe[6] == 'n' &&
-            dupe[7] == 'g')
-        {
-            return JS::ubi::Node::canonicalTypeName<JSString>();
-        }
-
-        return nullptr;
-    }
-
-    MOZ_ASSERT(14 == strlen("js::LazyScript"));
-    if (length == 14) {
-        if (dupe[0]  == 'j' &&
-            dupe[1]  == 's' &&
-            dupe[2]  == ':' &&
-            dupe[3]  == ':' &&
-            dupe[4]  == 'L' &&
-            dupe[5]  == 'a' &&
-            dupe[6]  == 'z' &&
-            dupe[7]  == 'y' &&
-            dupe[8]  == 'S' &&
-            dupe[9]  == 'c' &&
-            dupe[10] == 'r' &&
-            dupe[11] == 'i' &&
-            dupe[12] == 'p' &&
-            dupe[13] == 't')
-        {
-            return JS::ubi::Node::canonicalTypeName<js::LazyScript>();
-        }
-
-        return nullptr;
-    }
-
-    MOZ_ASSERT(16 == strlen("js::jit::JitCode"));
-    if (length == 16) {
-        if (dupe[0]  == 'j' &&
-            dupe[1]  == 's' &&
-            dupe[2]  == ':' &&
-            dupe[3]  == ':' &&
-            dupe[4]  == 'j' &&
-            dupe[5]  == 'i' &&
-            dupe[6]  == 't' &&
-            dupe[7]  == ':' &&
-            dupe[8]  == ':' &&
-            dupe[9]  == 'J' &&
-            dupe[10] == 'i' &&
-            dupe[11] == 't' &&
-            dupe[12] == 'C' &&
-            dupe[13] == 'o' &&
-            dupe[14] == 'd' &&
-            dupe[15] == 'e')
-        {
-            return JS::ubi::Node::canonicalTypeName<js::jit::JitCode>();
-        }
-
-        return nullptr;
-    }
-
-    return nullptr;
-}
-
 // All operations on null ubi::Nodes crash.
 CoarseType Concrete<void>::coarseType() const      { MOZ_CRASH("null ubi::Node"); }
 const char16_t* Concrete<void>::typeName() const   { MOZ_CRASH("null ubi::Node"); }

toolkit/devtools/server/HeapSnapshot.cpp

@@ -140,13 +140,9 @@ HeapSnapshot::saveNode(const protobuf::Node& node)
   auto duplicatedTypeName = reinterpret_cast<const char16_t*>(
     node.typename_().data());
   auto length = node.typename_().length() / sizeof(char16_t);
-  auto typeName = JS::ubi::Node::getCanonicalTypeName(duplicatedTypeName, length);
-  if (!typeName) {
-    typeName = borrowUniqueString(duplicatedTypeName, length);
-    if (!typeName)
-      return false;
-  }
-  MOZ_ASSERT(typeName);
+  auto typeName = borrowUniqueString(duplicatedTypeName, length);
+  if (!typeName)
+    return false;
 
   if (!node.has_size())
     return false;