Use StackArgumenstAccessor and kPCOnStackSize/kFPOnStackSize to compute stack address/operand

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 33d668d4f20a41ababd7e208df6d4a4151083e02..20c56226e8cca27078e518d32fb357ecd1e5b49b 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -140,10 +140,9 @@ void FullCodeGenerator::Generate() {
     Label ok;
     __ testq(rcx, rcx);
     __ j(zero, &ok, Label::kNear);
-    // +1 for return address.
-    int receiver_offset = (info->scope()->num_parameters() + 1) * kPointerSize;
+    StackArgumentsAccessor args(rsp, info->scope()->num_parameters());
     __ LoadRoot(kScratchRegister, Heap::kUndefinedValueRootIndex);
-    __ movq(Operand(rsp, receiver_offset), kScratchRegister);
+    __ movq(args.GetReceiverOperand(), kScratchRegister);
     __ bind(&ok);
   }
 
@@ -678,7 +677,8 @@ MemOperand FullCodeGenerator::StackOperand(Variable* var) {
   int offset = -var->index() * kPointerSize;
   // Adjust by a (parameter or local) base offset.
   if (var->IsParameter()) {
-    offset += (info_->scope()->num_parameters() + 1) * kPointerSize;
+    offset += kFPOnStackSize + kPCOnStackSize +
+              (info_->scope()->num_parameters() - 1) * kPointerSize;
   } else {
     offset += JavaScriptFrameConstants::kLocal0Offset;
   }
@@ -2632,7 +2632,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   }
 
   // Push the receiver of the enclosing function and do runtime call.
-  __ push(Operand(rbp, (2 + info_->scope()->num_parameters()) * kPointerSize));
+  StackArgumentsAccessor args(rbp, info_->scope()->num_parameters());
+  __ push(args.GetReceiverOperand());
 
   // Push the language mode.
   __ Push(Smi::FromInt(language_mode()));