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

src/compiler/linkage.cc

Index: src/compiler/linkage.cc
diff --git a/src/compiler/linkage.cc b/src/compiler/linkage.cc
index 3880f2fa088e2e14ae236b3a678009a8cfd7495d..eaab6aefe40ac8f0c5ddd3fc53e3507bbc26e445 100644
--- a/src/compiler/linkage.cc
+++ b/src/compiler/linkage.cc
@@ -63,6 +63,9 @@ std::ostream& operator<<(std::ostream& os, const CallDescriptor::Kind& k) {
     case CallDescriptor::kCallAddress:
       os << "Addr";
       break;
+    case CallDescriptor::kLazyBailout:
+      os << "LazyBail";
+      break;
   }
   return os;
 }
@@ -351,6 +354,31 @@ CallDescriptor* Linkage::GetRuntimeCallDescriptor(
 }
 
 
+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) {