[stubs] Add CSA::IsSymbol() and CSA::IsPrivateSymbol().

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index 17862fac45519286bcb2d30c51addb69ed3bcd6d..da4cc9d24f4d72db429387c6376fcc8dc666a956 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -2915,6 +2915,26 @@ Node* CodeStubAssembler::IsString(Node* object) {
                               Int32Constant(FIRST_NONSTRING_TYPE));
 }
 
+Node* CodeStubAssembler::IsSymbol(Node* object) {
+  return HasInstanceType(object, SYMBOL_TYPE);

[Igor Sheludko, 2016/12/13 20:56:28]

IsSymbolMap(LoadMap(object)) does not require loading an instance type field.

[gsathya, 2016/12/13 22:01:03]

Doh ofc. Changed

+}
+
+Node* CodeStubAssembler::IsPrivateSymbol(Node* object) {
+  Label out(this);
+  Variable var_result(this, MachineType::PointerRepresentation());

[Igor Sheludko, 2016/12/13 20:56:28]

CSA expects kWord32 nodes as a condition in Branch, so the result should be a
kWord32. (The CSA graph verification is almost there).

[gsathya, 2016/12/13 22:01:04]

Ah, okay. Changed.

+  var_result.Bind(IntPtrConstant(0));

[Igor Sheludko, 2016/12/13 20:56:28]

Same here: Int32Constant().

[gsathya, 2016/12/13 22:01:03]

Done.

+
+  GotoUnless(IsSymbolMap(LoadMap(object)), &out);

[Igor Sheludko, 2016/12/13 20:56:28]

IsSymbol(object)

[gsathya, 2016/12/13 22:01:04]

Done.

+  Node* const flags =
+      SmiToWord32(LoadObjectField(object, Symbol::kFlagsOffset));
+  const int kPrivateMask = 1 << Symbol::kPrivateBit;
+  var_result.Bind(IsSetWord32(flags, kPrivateMask));
+  Goto(&out);
+
+  Bind(&out);
+  return var_result.value();

[Igor Sheludko, 2016/12/13 20:56:28]

You may want to use Select() for this.

[gsathya, 2016/12/13 22:01:03]

I did initially but didn't look very readable to me. Changed.

+}
+
 Node* CodeStubAssembler::IsNativeContext(Node* object) {
   return WordEqual(LoadMap(object), LoadRoot(Heap::kNativeContextMapRootIndex));
 }
@@ -4271,10 +4291,9 @@ void CodeStubAssembler::TryToName(Node* key, Label* if_keyisindex,
   Goto(if_keyisindex);
 
   Bind(&if_keyisnotindex);
-  Node* key_instance_type = LoadInstanceType(key);
   // Symbols are unique.
-  GotoIf(Word32Equal(key_instance_type, Int32Constant(SYMBOL_TYPE)),
-         if_keyisunique);
+  GotoIf(IsSymbol(key), if_keyisunique);
+  Node* key_instance_type = LoadInstanceType(key);

[Igor Sheludko, 2016/12/13 20:56:28]

On this path we are loading map twice. How about: LoadMap, IsSymbolMap,
LoadMapInstanceType?

[gsathya, 2016/12/13 22:01:04]

Done.

   // Miss if |key| is not a String.
   STATIC_ASSERT(FIRST_NAME_TYPE == FIRST_TYPE);
   GotoUnless(IsStringInstanceType(key_instance_type), if_bailout);