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

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/arm/lithium-codegen-arm.h"
 #include "src/arm/lithium-gap-resolver-arm.h"
 #include "src/base/bits.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/cpu-profiler.h"
@@ skipping 2600 matching lines @@
                                Handle<String>class_name,
                                Register input,
                                Register temp,
                                Register temp2) {
   DCHECK(!input.is(temp));
   DCHECK(!input.is(temp2));
   DCHECK(!temp.is(temp2));
 
   __ JumpIfSmi(input, is_false);
 
+  STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
+  __ CompareObjectType(input, temp, temp2, FIRST_JS_RECEIVER_TYPE);
+  __ b(lt, is_false);
+
+  // Objects with [[Call]] have class 'Function'.
+  __ ldrb(temp2, FieldMemOperand(temp, Map::kBitFieldOffset));
+  __ tst(temp2, Operand(1 << Map::kIsCallable));
   if (String::Equals(isolate()->factory()->Function_string(), class_name)) {
-    // 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);
-    __ CompareObjectType(input, temp, temp2, FIRST_SPEC_OBJECT_TYPE);
-    __ b(lt, is_false);
-    __ b(eq, is_true);
-    __ cmp(temp2, Operand(LAST_SPEC_OBJECT_TYPE));
-    __ b(eq, is_true);
+    __ b(ne, is_true);
   } 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.
-    __ ldr(temp, FieldMemOperand(input, HeapObject::kMapOffset));
-    __ ldrb(temp2, FieldMemOperand(temp, Map::kInstanceTypeOffset));
-    __ sub(temp2, temp2, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-    __ cmp(temp2, Operand(LAST_NONCALLABLE_SPEC_OBJECT_TYPE -
-                          FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-    __ b(gt, is_false);

[Jakob Kummerow, 2015/09/03 13:19:23]

For the record: I think this signed comparison was actually a bug. Should've
been unsigned.

+    __ b(ne, is_false);
   }
 
-  // Now we are in the FIRST-LAST_NONCALLABLE_SPEC_OBJECT_TYPE range.
+  // Now we are in the FIRST-LAST_JS_RECEIVER_TYPE range.
   // Check if the constructor in the map is a function.
   Register instance_type = ip;
   __ GetMapConstructor(temp, temp, temp2, instance_type);
 
   // Objects with a non-function constructor have class 'Object'.
   __ cmp(instance_type, Operand(JS_FUNCTION_TYPE));
-  if (class_name->IsOneByteEqualTo(STATIC_CHAR_VECTOR("Object"))) {
+  if (String::Equals(isolate()->factory()->Object_string(), class_name)) {
     __ b(ne, is_true);
   } else {
     __ b(ne, is_false);
   }
 
   // temp now contains the constructor function. Grab the
   // instance class name from there.
   __ ldr(temp, FieldMemOperand(temp, JSFunction::kSharedFunctionInfoOffset));
   __ ldr(temp, FieldMemOperand(temp,
                                SharedFunctionInfo::kInstanceClassNameOffset));
@@ skipping 3211 matching lines @@
   __ push(ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8