[runtime] Optimize and unify rest parameters.

src/full-codegen/arm/full-codegen-arm.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 246 matching lines @@
   if (new_target_var != nullptr) {
     Comment cmnt(masm_, "[ new.target");
     SetVar(new_target_var, r3, r0, r2);
   }
 
   // Possibly allocate RestParameters
   int rest_index;
   Variable* rest_param = scope()->rest_parameter(&rest_index);
   if (rest_param) {
     Comment cmnt(masm_, "[ Allocate rest parameter array");
-
-    int num_parameters = info->scope()->num_parameters();
-    int offset = num_parameters * kPointerSize;
-
-    __ mov(RestParamAccessDescriptor::parameter_count(),
-           Operand(Smi::FromInt(num_parameters)));
-    __ add(RestParamAccessDescriptor::parameter_pointer(), fp,
-           Operand(StandardFrameConstants::kCallerSPOffset + offset));
-    __ mov(RestParamAccessDescriptor::rest_parameter_index(),
-           Operand(Smi::FromInt(rest_index)));
+    if (!function_in_register_r1) {
+      __ ldr(r1, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
+    }
+    FastNewRestParameterStub stub(isolate());
+    __ CallStub(&stub);
     function_in_register_r1 = false;
-
-    RestParamAccessStub stub(isolate());
-    __ CallStub(&stub);
-
     SetVar(rest_param, r0, r1, r2);
   }
 
   Variable* arguments = scope()->arguments();
   if (arguments != NULL) {
     // Function uses arguments object.
     Comment cmnt(masm_, "[ Allocate arguments object");
     DCHECK(r1.is(ArgumentsAccessNewDescriptor::function()));
     if (!function_in_register_r1) {
       // Load this again, if it's used by the local context below.
@@ skipping 4466 matching lines @@
   DCHECK(interrupt_address ==
          isolate->builtins()->OsrAfterStackCheck()->entry());
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM