[crankshaft] Generate lazy bailout point for HProlog instruction only when it is necessary.

src/crankshaft/s390/lithium-s390.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/crankshaft/s390/lithium-s390.h"
 
 #include <sstream>
 
 #include "src/crankshaft/hydrogen-osr.h"
 #include "src/crankshaft/lithium-inl.h"
@@ skipping 796 matching lines @@
 #endif
 
   if (FLAG_stress_pointer_maps && !instr->HasPointerMap()) {
     instr = AssignPointerMap(instr);
   }
   if (FLAG_stress_environments && !instr->HasEnvironment()) {
     instr = AssignEnvironment(instr);
   }
   chunk_->AddInstruction(instr, current_block_);
 
-  if (instr->IsCall() || instr->IsPrologue()) {
+  if (instr->IsCall()) {
     HValue* hydrogen_value_for_lazy_bailout = hydrogen_val;
     if (hydrogen_val->HasObservableSideEffects()) {
       HSimulate* sim = HSimulate::cast(hydrogen_val->next());
       sim->ReplayEnvironment(current_block_->last_environment());
       hydrogen_value_for_lazy_bailout = sim;
     }
     LInstruction* bailout = AssignEnvironment(new (zone()) LLazyBailout());
     bailout->set_hydrogen_value(hydrogen_value_for_lazy_bailout);
     chunk_->AddInstruction(bailout, current_block_);
   }
 }
 
 LInstruction* LChunkBuilder::DoPrologue(HPrologue* instr) {
-  return new (zone()) LPrologue();
+  LInstruction* result = new (zone()) LPrologue();
+  if (info_->num_heap_slots() > 0) {
+    result = MarkAsCall(result, instr);
+  }
+  return result;
 }
 
 LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
   return new (zone()) LGoto(instr->FirstSuccessor());
 }
 
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
   HValue* value = instr->value();
   Representation r = value->representation();
   HType type = value->type();
@@ skipping 1453 matching lines @@
   return AssignPointerMap(result);
 }
 
 LInstruction* LChunkBuilder::DoStoreFrameContext(HStoreFrameContext* instr) {
   LOperand* context = UseRegisterAtStart(instr->context());
   return new (zone()) LStoreFrameContext(context);
 }
 
 }  // namespace internal
 }  // namespace v8