Switch CallConstructStub to take new.target in register.

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index e67b4fd2beb291703281082aa711f1c21c975fc3..1477cddb753586965563923742f9a45ea82e57ec 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -2985,7 +2985,8 @@ void CallConstructStub::Generate(MacroAssembler* masm) {
   // 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;
 
@@ -2997,7 +2998,13 @@ void CallConstructStub::Generate(MacroAssembler* masm) {
                          &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) {
@@ -3020,9 +3027,7 @@ void CallConstructStub::Generate(MacroAssembler* masm) {
   }
 
   if (IsSuperConstructorCall()) {
-    __ Mov(x4, Operand(1 * kPointerSize));
-    __ Add(x4, x4, Operand(x0, LSL, kPointerSizeLog2));
-    __ Peek(x3, x4);
+    __ Mov(x3, x4);
   } else {
     __ Mov(x3, function);
   }