[runtime] Implement %_ToLength via ToLengthStub.

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/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
@@ skipping 3779 matching lines @@
   DCHECK_EQ(args->length(), 1);
   // Load the argument into r0 and call the stub.
   VisitForAccumulatorValue(args->at(0));
 
   NumberToStringStub stub(isolate());
   __ CallStub(&stub);
   context()->Plug(r0);
 }
 
 
+void FullCodeGenerator::EmitToLength(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  DCHECK_EQ(1, args->length());
+
+  // Load the argument into r0 and convert it.
+  VisitForAccumulatorValue(args->at(0));
+
+  ToLengthStub stub(isolate());
+  __ CallStub(&stub);
+  context()->Plug(r0);

[Jarin, 2015/10/19 06:50:16]

I see nearly the same code in EmitToString, EmitToNumber and EmitToName. Could
we somehow unify that?

Also, could you just say PlugTOS() here and move the method(s) into
full-codegen.cc?

[Michael Starzinger, 2015/10/19 08:21:08]

Nah, PlugTOS targets top-of-stack, not the accumulator/result register.

+}
+
+
 void FullCodeGenerator::EmitToString(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   DCHECK_EQ(1, args->length());
 
   // Load the argument into r0 and convert it.
   VisitForAccumulatorValue(args->at(0));
 
   ToStringStub stub(isolate());
   __ CallStub(&stub);
   context()->Plug(r0);
@@ skipping 1479 matching lines @@
   DCHECK(interrupt_address ==
          isolate->builtins()->OsrAfterStackCheck()->entry());
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM