[turbofan] Introduce lazy bailout, masked as a call.

src/compiler/linkage.cc

 // Copyright 2014 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.
 
 #include "src/code-stubs.h"
 #include "src/compiler.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/frame.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node.h"
@@ skipping 45 matching lines @@
   switch (k) {
     case CallDescriptor::kCallCodeObject:
       os << "Code";
       break;
     case CallDescriptor::kCallJSFunction:
       os << "JS";
       break;
     case CallDescriptor::kCallAddress:
       os << "Addr";
       break;
+    case CallDescriptor::kLazyBailout:
+      os << "LazyBail";
+      break;
   }
   return os;
 }
 
 
 std::ostream& operator<<(std::ostream& os, const CallDescriptor& d) {
   // TODO(svenpanne) Output properties etc. and be less cryptic.
   return os << d.kind() << ":" << d.debug_name() << ":r" << d.ReturnCount()
             << "s" << d.StackParameterCount() << "i" << d.InputCount() << "f"
             << d.FrameStateCount() << "t" << d.SupportsTailCalls();
@@ skipping 268 matching lines @@
       locations.Build(),                // location_sig
       js_parameter_count,               // stack_parameter_count
       properties,                       // properties
       kNoCalleeSaved,                   // callee-saved
       kNoCalleeSaved,                   // callee-saved fp
       flags,                            // flags
       function->name);                  // debug name
 }
 
 
+CallDescriptor* Linkage::GetLazyBailoutDescriptor(Zone* zone) {
+  const size_t return_count = 0;
+  const size_t parameter_count = 0;
+
+  LocationSignature::Builder locations(zone, return_count, parameter_count);
+  MachineSignature::Builder types(zone, return_count, parameter_count);
+
+  // The target is ignored, but we need to give some values here.
+  MachineType target_type = kMachAnyTagged;
+  LinkageLocation target_loc = regloc(kJSFunctionRegister);
+  return new (zone) CallDescriptor(      // --
+      CallDescriptor::kLazyBailout,      // kind
+      target_type,                       // target MachineType
+      target_loc,                        // target location
+      types.Build(),                     // machine_sig
+      locations.Build(),                 // location_sig
+      0,                                 // stack_parameter_count
+      Operator::kNoThrow,                // properties
+      kNoCalleeSaved,                    // callee-saved
+      kNoCalleeSaved,                    // callee-saved fp
+      CallDescriptor::kNeedsFrameState,  // flags
+      "lazy-bailout");
+}
+
+
 CallDescriptor* Linkage::GetJSCallDescriptor(Zone* zone, bool is_osr,
                                              int js_parameter_count,
                                              CallDescriptor::Flags flags) {
   const size_t return_count = 1;
   const size_t context_count = 1;
   const size_t parameter_count = js_parameter_count + context_count;
 
   LocationSignature::Builder locations(zone, return_count, parameter_count);
   MachineSignature::Builder types(zone, return_count, parameter_count);
 
@@ skipping 163 matching lines @@
     return LinkageLocation::ForCalleeFrameSlot(spill_index);
   } else {
     // Parameter. Use the assigned location from the incoming call descriptor.
     int parameter_index = 1 + index;  // skip index 0, which is the target.
     return incoming_->GetInputLocation(parameter_index);
   }
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8