Move function prototype handling into a special handler rather than IC

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-stubs.h"
 #include "src/hydrogen-osr.h"
@@ skipping 3000 matching lines @@
   }
   Handle<Code> ic = LoadIC::initialize_stub(isolate(), NOT_CONTEXTUAL);
   CallCode(ic, RelocInfo::CODE_TARGET, instr);
 }
 
 
 void LCodeGen::DoLoadFunctionPrototype(LLoadFunctionPrototype* instr) {
   Register function = ToRegister(instr->function());
   Register result = ToRegister(instr->result());
 
-  // Check that the function really is a function.
-  __ CmpObjectType(function, JS_FUNCTION_TYPE, result);
-  DeoptimizeIf(not_equal, instr->environment());
-
-  // Check whether the function has an instance prototype.
-  Label non_instance;
-  __ testb(FieldOperand(result, Map::kBitFieldOffset),
-           Immediate(1 << Map::kHasNonInstancePrototype));
-  __ j(not_zero, &non_instance, Label::kNear);
-
   // Get the prototype or initial map from the function.
   __ movp(result,
          FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
 
   // Check that the function has a prototype or an initial map.
   __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
   DeoptimizeIf(equal, instr->environment());
 
   // If the function does not have an initial map, we're done.
   Label done;
   __ CmpObjectType(result, MAP_TYPE, kScratchRegister);
   __ j(not_equal, &done, Label::kNear);
 
   // Get the prototype from the initial map.
   __ movp(result, FieldOperand(result, Map::kPrototypeOffset));
-  __ jmp(&done, Label::kNear);
-
-  // Non-instance prototype: Fetch prototype from constructor field
-  // in the function's map.
-  __ bind(&non_instance);
-  __ movp(result, FieldOperand(result, Map::kConstructorOffset));
 
   // All done.
   __ bind(&done);
 }
 
 
 void LCodeGen::DoLoadRoot(LLoadRoot* instr) {
   Register result = ToRegister(instr->result());
   __ LoadRoot(result, instr->index());
 }
@@ skipping 2798 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64