Switch CallConstructStub to take new.target in register.

src/arm64/code-stubs-arm64.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_ARM64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 2967 matching lines @@
   ASM_LOCATION("CallFunctionStub::Generate");
   CallFunctionNoFeedback(masm, argc(), NeedsChecks(), CallAsMethod());
 }
 
 
 void CallConstructStub::Generate(MacroAssembler* masm) {
   ASM_LOCATION("CallConstructStub::Generate");
   // x0 : number of arguments
   // x1 : the function to call
   // x2 : feedback vector
-  // x3 : slot in feedback vector (smi) (if r2 is not the megamorphic symbol)
+  // x3 : slot in feedback vector (Smi, for RecordCallTarget)
+  // x4 : original constructor (for IsSuperConstructorCall)
   Register function = x1;
   Label slow, non_function_call;
 
   // Check that the function is not a smi.
   __ JumpIfSmi(function, &non_function_call);
   // Check that the function is a JSFunction.
   Register object_type = x10;
   __ JumpIfNotObjectType(function, object_type, object_type, JS_FUNCTION_TYPE,
                          &slow);
 
   if (RecordCallTarget()) {
+    if (IsSuperConstructorCall()) {
+      __ Push(x4);
+    }
     GenerateRecordCallTarget(masm, x0, function, x2, x3, x4, x5, x11);

[jbramley, 2015/07/14 16:57:35]

ARM64's GenerateRecordCallTarget allows the scratch registers to be specified,
so it should be possible to just specify something other than x4 and skip the
push/pop sequence.

[Michael Starzinger, 2015/07/15 07:36:36]

Acknowledged. I initially tried that, but CallStubInRecordCallTarget still
clobbers x4. But I left a TODO here.

+    if (IsSuperConstructorCall()) {
+      __ Pop(x4);
+    }
 
     __ Add(x5, x2, Operand::UntagSmiAndScale(x3, kPointerSizeLog2));
     if (FLAG_pretenuring_call_new) {
       // Put the AllocationSite from the feedback vector into x2.
       // By adding kPointerSize we encode that we know the AllocationSite
       // entry is at the feedback vector slot given by x3 + 1.
       __ Ldr(x2, FieldMemOperand(x5, FixedArray::kHeaderSize + kPointerSize));
     } else {
     Label feedback_register_initialized;
       // Put the AllocationSite from the feedback vector into x2, or undefined.
       __ Ldr(x2, FieldMemOperand(x5, FixedArray::kHeaderSize));
       __ Ldr(x5, FieldMemOperand(x2, AllocationSite::kMapOffset));
       __ JumpIfRoot(x5, Heap::kAllocationSiteMapRootIndex,
                     &feedback_register_initialized);
       __ LoadRoot(x2, Heap::kUndefinedValueRootIndex);
       __ bind(&feedback_register_initialized);
     }
 
     __ AssertUndefinedOrAllocationSite(x2, x5);
   }
 
   if (IsSuperConstructorCall()) {
-    __ Mov(x4, Operand(1 * kPointerSize));
-    __ Add(x4, x4, Operand(x0, LSL, kPointerSizeLog2));
-    __ Peek(x3, x4);
+    __ Mov(x3, x4);
   } else {
     __ Mov(x3, function);
   }
 
   // Jump to the function-specific construct stub.
   Register jump_reg = x4;
   Register shared_func_info = jump_reg;
   Register cons_stub = jump_reg;
   Register cons_stub_code = jump_reg;
   __ Ldr(shared_func_info,
@@ skipping 2791 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64