Add code comments to slow paths.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 1589 matching lines @@
   return summary;
 }
 
 
 class CheckStackOverflowSlowPath : public SlowPathCode {
  public:
   explicit CheckStackOverflowSlowPath(CheckStackOverflowInstr* instruction)
       : instruction_(instruction) { }
 
   virtual void EmitNativeCode(FlowGraphCompiler* compiler) {
+    __ Comment("CheckStackOverflowSlowPath");
     __ Bind(entry_label());
     compiler->SaveLiveRegisters(instruction_->locs());
     compiler->GenerateCallRuntime(instruction_->token_pos(),
                                   kStackOverflowRuntimeEntry,
                                   instruction_->locs());
     compiler->RestoreLiveRegisters(instruction_->locs());
     __ jmp(exit_label());
   }
 
  private:
@@ skipping 341 matching lines @@
   return summary;
 }
 
 
 class BoxDoubleSlowPath : public SlowPathCode {
  public:
   explicit BoxDoubleSlowPath(BoxDoubleInstr* instruction)
       : instruction_(instruction) { }
 
   virtual void EmitNativeCode(FlowGraphCompiler* compiler) {
+    __ Comment("BoxDoubleSlowPath");
     __ Bind(entry_label());
     const Class& double_class = compiler->double_class();
     const Code& stub =
         Code::Handle(StubCode::GetAllocationStubForClass(double_class));
     const ExternalLabel label(double_class.ToCString(), stub.EntryPoint());
 
     LocationSummary* locs = instruction_->locs();
     locs->live_registers()->Remove(locs->out());
 
     compiler->SaveLiveRegisters(locs);
@@ skipping 453 matching lines @@
 
 void ShiftMintOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64