Resolve references to "this" the same way as normal variables

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 90d309504218bffd333366d1a2c03752c71bfb58..5741f7d178bba216f51023175a56294b402fa2fa 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -115,7 +115,8 @@ void FullCodeGenerator::Generate() {
   // Sloppy mode functions and builtins need to replace the receiver with the
   // global proxy when called as functions (without an explicit receiver
   // object).
-  if (is_sloppy(info->language_mode()) && !info->is_native()) {
+  if (is_sloppy(info->language_mode()) && !info->is_native() &&
+      info->scope()->has_this_declaration()) {
     Label ok;
     // +1 for return address.
     StackArgumentsAccessor args(rsp, info->scope()->num_parameters());
@@ -209,8 +210,10 @@ void FullCodeGenerator::Generate() {
 
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    for (int i = 0; i < num_parameters; i++) {
-      Variable* var = scope()->parameter(i);
+    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
+      CHECK_NOT_NULL(var);

[adamk, 2015/04/22 15:50:54]

Seems unnecessary since receiver() already has this check and the next line will
crash anyway; if you want to keep it please change to DCHECK.

[wingo, 2015/04/23 14:16:02]

Good catch; was vestigial.  Removed.

       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;
@@ -2989,8 +2992,9 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   __ Push(Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
 
   // Push the receiver of the enclosing function and do runtime call.
-  StackArgumentsAccessor args(rbp, info_->scope()->num_parameters());
-  __ Push(args.GetReceiverOperand());
+  Variable* this_var = scope()->LookupThis();
+  CHECK_NOT_NULL(this_var);

[adamk, 2015/04/22 15:50:54]

DCHECK

[wingo, 2015/04/23 14:16:02]

Done.

+  __ Push(VarOperand(this_var, kScratchRegister));
 
   // Push the language mode.
   __ Push(Smi::FromInt(language_mode()));