Cleanup Generate_JSConstructStubHelper a bit.

src/x64/builtins-x64.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/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 81 matching lines @@
   __ j(above_equal, &ok);
 
   CallRuntimePassFunction(masm, Runtime::kTryInstallOptimizedCode);
   GenerateTailCallToReturnedCode(masm);
 
   __ bind(&ok);
   GenerateTailCallToSharedCode(masm);
 }
 
 
-static void Generate_Runtime_NewObject(MacroAssembler* masm,
-                                       bool create_memento,
-                                       Register original_constructor,
-                                       Label* count_incremented,
-                                       Label* allocated) {
-  int offset = kPointerSize;
-  if (create_memento) {
-    // Get the cell or allocation site.
-    __ movp(rdi, Operand(rsp, kPointerSize * 3));
-    __ Push(rdi);
-    offset += kPointerSize;
-  }
-
-  // Must restore rsi (context) and rdi (constructor) before calling runtime.
-  __ movp(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
-  __ movp(rdi, Operand(rsp, offset));
-  __ Push(rdi);
-  __ Push(original_constructor);
-  if (create_memento) {
-    __ CallRuntime(Runtime::kNewObjectWithAllocationSite, 3);
-  } else {
-    __ CallRuntime(Runtime::kNewObject, 2);
-  }
-  __ movp(rbx, rax);  // store result in rbx
-
-  // Runtime_NewObjectWithAllocationSite increments allocation count.
-  // Skip the increment.
-  if (create_memento) {
-    __ jmp(count_incremented);
-  } else {
-    __ jmp(allocated);
-  }
-}
-
-
 static void Generate_JSConstructStubHelper(MacroAssembler* masm,
                                            bool is_api_function,
                                            bool create_memento) {
   // ----------- S t a t e -------------
   //  -- rax: number of arguments
   //  -- rdi: constructor function
   //  -- rbx: allocation site or undefined
   //  -- rdx: original constructor
   // -----------------------------------
 
   // Should never create mementos for api functions.
   DCHECK(!is_api_function || !create_memento);
 
   // Enter a construct frame.
   {
     FrameScope scope(masm, StackFrame::CONSTRUCT);
 
     if (create_memento) {
       __ AssertUndefinedOrAllocationSite(rbx);
       __ Push(rbx);
     }
 
     // Preserve the incoming parameters on the stack.
     __ Integer32ToSmi(rax, rax);
     __ Push(rax);
     __ Push(rdi);
     __ Push(rdx);
 
-    Label rt_call, normal_new, allocated, count_incremented;
-    __ cmpp(rdx, rdi);
-    __ j(equal, &normal_new);
-
-    Generate_Runtime_NewObject(masm, create_memento, rdx, &count_incremented,
-                               &allocated);
-
-    __ bind(&normal_new);
     // Try to allocate the object without transitioning into C code. If any of
     // the preconditions is not met, the code bails out to the runtime call.
+    Label rt_call, allocated;
     if (FLAG_inline_new) {
       Label undo_allocation;
 
+      __ cmpp(rdx, rdi);
+      __ j(not_equal, &rt_call);
+
       ExternalReference debug_step_in_fp =
           ExternalReference::debug_step_in_fp_address(masm->isolate());
       __ Move(kScratchRegister, debug_step_in_fp);
       __ cmpp(Operand(kScratchRegister, 0), Immediate(0));
       __ j(not_equal, &rt_call);
 
       // Verified that the constructor is a JSFunction.
       // Load the initial map and verify that it is in fact a map.
       // rdi: constructor
       __ movp(rax, FieldOperand(rdi, JSFunction::kPrototypeOrInitialMapOffset));
@@ skipping 22 matching lines @@
         __ cmpl(rsi, Immediate(Map::kSlackTrackingCounterEnd));
         __ j(less, &allocate);
         // Decrease generous allocation count.
         __ subl(FieldOperand(rax, Map::kBitField3Offset),
                 Immediate(1 << Map::Counter::kShift));
 
         __ cmpl(rsi, Immediate(Map::kSlackTrackingCounterEnd));
         __ j(not_equal, &allocate);
 
         __ Push(rax);
+        __ Push(rdx);

[arv (Not doing code reviews), 2015/07/10 16:21:51]

Do we care about the extra cost of the push/pop here?

[Michael Starzinger, 2015/07/10 16:39:54]

The push/pop is right before and after a runtime call, which in turn goes
through the CEntryStub that sets up and tears down an entire exit-frame. Also,
slack tracking runs for exactly 8 allocations per per initial map. Also,
Runtime_FinalizeInstanceSize will perform a full traversal over the entire
transition tree of the initial map. So no, I don't think we care.

         __ Push(rdi);
 
         __ Push(rdi);  // constructor
         __ CallRuntime(Runtime::kFinalizeInstanceSize, 1);
 
         __ Pop(rdi);
+        __ Pop(rdx);
         __ Pop(rax);
         __ movl(rsi, Immediate(Map::kSlackTrackingCounterEnd - 1));
 
         __ bind(&allocate);
       }
 
       // Now allocate the JSObject on the heap.
       __ movzxbp(rdi, FieldOperand(rax, Map::kInstanceSizeOffset));
       __ shlp(rdi, Immediate(kPointerSizeLog2));
       if (create_memento) {
@@ skipping 134 matching lines @@
 
       // Undo the setting of the new top so that the heap is verifiable. For
       // example, the map's unused properties potentially do not match the
       // allocated objects unused properties.
       // rbx: JSObject (previous new top)
       __ bind(&undo_allocation);
       __ UndoAllocationInNewSpace(rbx);
     }
 
     // Allocate the new receiver object using the runtime call.
-    // rdi: function (constructor)
+    // rdx: original constructor
     __ bind(&rt_call);
-    Generate_Runtime_NewObject(masm, create_memento, rdi, &count_incremented,
-                               &allocated);
+    int offset = kPointerSize;
+    if (create_memento) {
+      // Get the cell or allocation site.
+      __ movp(rdi, Operand(rsp, kPointerSize * 3));
+      __ Push(rdi);
+      offset += kPointerSize;
+    }
+
+    // Must restore rsi (context) and rdi (constructor) before calling runtime.
+    __ movp(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
+    __ movp(rdi, Operand(rsp, offset));
+    __ Push(rdi);
+    __ Push(rdx);
+    if (create_memento) {
+      __ CallRuntime(Runtime::kNewObjectWithAllocationSite, 3);
+    } else {
+      __ CallRuntime(Runtime::kNewObject, 2);
+    }
+    __ movp(rbx, rax);  // store result in rbx
+
+    // Runtime_NewObjectWithAllocationSite increments allocation count.
+    // Skip the increment.
+    Label count_incremented;
+    if (create_memento) {
+      __ jmp(&count_incremented);
+    } else {
+      __ jmp(&allocated);
+    }
 
     // New object allocated.
     // rbx: newly allocated object
     __ bind(&allocated);
 
     if (create_memento) {
       __ movp(rcx, Operand(rsp, 3 * kPointerSize));
       __ Cmp(rcx, masm->isolate()->factory()->undefined_value());
       __ j(equal, &count_incremented);
       // rcx is an AllocationSite. We are creating a memento from it, so we
@@ skipping 1395 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64