[es6] Make new.target work in functions

src/arm64/builtins-arm64.cc

Index: src/arm64/builtins-arm64.cc
diff --git a/src/arm64/builtins-arm64.cc b/src/arm64/builtins-arm64.cc
index 08d0a116aaaeffa84df91ca15e570a1ea102425e..190486a2a7146b5d12417c8a2bbf8c2d2d4a63b0 100644
--- a/src/arm64/builtins-arm64.cc
+++ b/src/arm64/builtins-arm64.cc
@@ -331,6 +331,7 @@ static void Generate_Runtime_NewObject(MacroAssembler* masm,
 
 static void Generate_JSConstructStubHelper(MacroAssembler* masm,
                                            bool is_api_function,
+                                           bool use_new_target,
                                            bool create_memento) {
   // ----------- S t a t e -------------
   //  -- x0     : number of arguments
@@ -360,11 +361,17 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     Register argc = x0;
     Register constructor = x1;
     Register original_constructor = x3;
-    // x1: constructor function
+
+    // Preserve the incoming parameters on the stack.
     __ SmiTag(argc);
-    __ Push(argc, constructor);
-    // sp[0] : Constructor function.
-    // sp[1]: number of arguments (smi-tagged)
+    if (use_new_target) {
+      __ Push(argc, constructor, original_constructor);
+    } else {
+      __ Push(argc, constructor);
+    }
+    // sp[0]: new.target (if used)
+    // sp[0/1]: Constructor function.
+    // sp[1/2]: number of arguments (smi-tagged)
 
     Label rt_call, count_incremented, allocated, normal_new;
     __ Cmp(constructor, original_constructor);
@@ -580,7 +587,8 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     __ Bind(&allocated);
 
     if (create_memento) {
-      __ Peek(x10, 2 * kXRegSize);
+      int offset = (use_new_target ? 3 : 2) * kXRegSize;
+      __ Peek(x10, offset);
       __ JumpIfRoot(x10, Heap::kUndefinedValueRootIndex, &count_incremented);
       // r2 is an AllocationSite. We are creating a memento from it, so we
       // need to increment the memento create count.
@@ -592,18 +600,24 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
       __ bind(&count_incremented);
     }
 
+    // Restore the parameters.
+    if (use_new_target) {
+      __ Pop(original_constructor);
+    }
     __ Pop(constructor);
 
-    __ Push(x4, x4);
-
     // Reload the number of arguments from the stack.
     // Set it up in x0 for the function call below.
-    // jssp[0]: receiver
-    // jssp[1]: receiver
-    // jssp[2]: number of arguments (smi-tagged)
-    __ Peek(argc, 2 * kXRegSize);  // Load number of arguments.
+    // jssp[0]: number of arguments (smi-tagged)
+    __ Peek(argc, 0);  // Load number of arguments.
     __ SmiUntag(argc);
 
+    if (use_new_target) {
+      __ Push(original_constructor, x4, x4);
+    } else {
+      __ Push(x4, x4);
+    }
+
     // Set up pointer to last argument.
     __ Add(x2, fp, StandardFrameConstants::kCallerSPOffset);
 
@@ -614,7 +628,8 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     // x2: address of last argument (caller sp)
     // jssp[0]: receiver
     // jssp[1]: receiver
-    // jssp[2]: number of arguments (smi-tagged)
+    // jssp[2]: new.target (if used)
+    // jssp[2/3]: number of arguments (smi-tagged)
     // Compute the start address of the copy in x3.
     __ Add(x3, x2, Operand(argc, LSL, kPointerSizeLog2));
     Label loop, entry, done_copying_arguments;
@@ -645,14 +660,17 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     }
 
     // Store offset of return address for deoptimizer.
-    if (!is_api_function) {
+    // TODO(arv): Remove the "!use_new_target" before supporting optimization
+    // of functions that reference new.target
+    if (!is_api_function && !use_new_target) {
       masm->isolate()->heap()->SetConstructStubDeoptPCOffset(masm->pc_offset());
     }
 
     // Restore the context from the frame.
     // x0: result
     // jssp[0]: receiver
-    // jssp[1]: number of arguments (smi-tagged)
+    // jssp[1]: new.target (if used)
+    // jssp[1/2]: number of arguments (smi-tagged)
     __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
 
     // If the result is an object (in the ECMA sense), we should get rid
@@ -680,8 +698,10 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     __ Bind(&exit);
     // x0: result
     // jssp[0]: receiver (newly allocated object)
-    // jssp[1]: number of arguments (smi-tagged)
-    __ Peek(x1, kXRegSize);
+    // jssp[1]: new.target (if used)
+    // jssp[1/2]: number of arguments (smi-tagged)
+    int offset = (use_new_target ? 2 : 1) * kXRegSize;
+    __ Peek(x1, offset);
 
     // Leave construct frame.
   }
@@ -694,12 +714,17 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
 
 
 void Builtins::Generate_JSConstructStubGeneric(MacroAssembler* masm) {
-  Generate_JSConstructStubHelper(masm, false, FLAG_pretenuring_call_new);
+  Generate_JSConstructStubHelper(masm, false, false, FLAG_pretenuring_call_new);
 }
 
 
 void Builtins::Generate_JSConstructStubApi(MacroAssembler* masm) {
-  Generate_JSConstructStubHelper(masm, true, false);
+  Generate_JSConstructStubHelper(masm, true, false, false);
+}
+
+
+void Builtins::Generate_JSConstructStubNewTarget(MacroAssembler* masm) {
+  Generate_JSConstructStubHelper(masm, false, true, FLAG_pretenuring_call_new);
 }