Revert of [es5] Class of object is "Function" if object has [[Call]].

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index c98da629475efb8275e07af656779109583dbffa..5586ed1ab264e7dd1f1a68ed40a313ff71e370e3 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -2544,20 +2544,30 @@
 
   __ JumpIfSmi(input, is_false);
 
-  STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
-  __ GetObjectType(input, temp, temp2);
-  __ Branch(is_false, lt, temp2, Operand(FIRST_JS_RECEIVER_TYPE));
-
-  // Objects with [[Call]] have class 'Function'.
-  __ lbu(temp2, FieldMemOperand(temp, Map::kBitFieldOffset));
-  __ And(temp2, temp2, Operand(1 << Map::kIsCallable));
   if (String::Equals(isolate()->factory()->Function_string(), class_name)) {
-    __ Branch(is_true, ne, temp2, Operand(zero_reg));
-  } else {
-    __ Branch(is_false, ne, temp2, Operand(zero_reg));
-  }
-
-  // Now we are in the FIRST-LAST_JS_RECEIVER_TYPE range.
+    // Assuming the following assertions, we can use the same compares to test
+    // for both being a function type and being in the object type range.
+    STATIC_ASSERT(NUM_OF_CALLABLE_SPEC_OBJECT_TYPES == 2);
+    STATIC_ASSERT(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE ==
+                  FIRST_SPEC_OBJECT_TYPE + 1);
+    STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE ==
+                  LAST_SPEC_OBJECT_TYPE - 1);
+    STATIC_ASSERT(LAST_SPEC_OBJECT_TYPE == LAST_TYPE);
+
+    __ GetObjectType(input, temp, temp2);
+    __ Branch(is_false, lt, temp2, Operand(FIRST_SPEC_OBJECT_TYPE));
+    __ Branch(is_true, eq, temp2, Operand(FIRST_SPEC_OBJECT_TYPE));
+    __ Branch(is_true, eq, temp2, Operand(LAST_SPEC_OBJECT_TYPE));
+  } else {
+    // Faster code path to avoid two compares: subtract lower bound from the
+    // actual type and do a signed compare with the width of the type range.
+    __ GetObjectType(input, temp, temp2);
+    __ Subu(temp2, temp2, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
+    __ Branch(is_false, gt, temp2, Operand(LAST_NONCALLABLE_SPEC_OBJECT_TYPE -
+                                           FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
+  }
+
+  // Now we are in the FIRST-LAST_NONCALLABLE_SPEC_OBJECT_TYPE range.
   // Check if the constructor in the map is a function.
   Register instance_type = scratch1();
   DCHECK(!instance_type.is(temp));