Return on the polymorphic hard deopt case to ensure we don't polute phis with fake type information.

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1025 matching lines @@
       }
       builder_->GotoNoSimulate(current->block_, merge_block);
     }
     current = current->next_;
   }
 
   // Merge deopt blocks, padding when necessary.
   current = merge_at_join_blocks_;
   while (current != NULL) {
     if (current->deopt_ && current->block_ != NULL) {
-      builder_->PadEnvironmentForContinuation(current->block_,
-                                              merge_block);
-      builder_->GotoNoSimulate(current->block_, merge_block);
+      current->block_->FinishExit(
+          HAbnormalExit::New(builder_->zone(), NULL), RelocInfo::kNoPosition);
     }
     current = current->next_;
   }
   builder_->set_current_block(merge_block);
 }
 
 
 HGraphBuilder::LoopBuilder::LoopBuilder(HGraphBuilder* builder,
                                         HValue* context,
                                         LoopBuilder::Direction direction)
@@ skipping 185 matching lines @@
   return header;
 }
 
 
 HValue* HGraphBuilder::BuildCheckHeapObject(HValue* obj) {
   if (obj->type().IsHeapObject()) return obj;
   return Add<HCheckHeapObject>(obj);
 }
 
 
-void HGraphBuilder::FinishExitWithHardDeoptimization(
-    const char* reason, HBasicBlock* continuation) {
-  PadEnvironmentForContinuation(current_block(), continuation);
+void HGraphBuilder::FinishExitWithHardDeoptimization(const char* reason) {
   Add<HDeoptimize>(reason, Deoptimizer::EAGER);
-  if (graph()->IsInsideNoSideEffectsScope()) {
-    GotoNoSimulate(continuation);
-  } else {
-    Goto(continuation);
-  }
+  FinishExitCurrentBlock(New<HAbnormalExit>());
 }
 
 
-void HGraphBuilder::PadEnvironmentForContinuation(
-    HBasicBlock* from,
-    HBasicBlock* continuation) {
-  if (continuation->last_environment() != NULL) {
-    // When merging from a deopt block to a continuation, resolve differences in
-    // environment by pushing constant 0 and popping extra values so that the
-    // environments match during the join. Push 0 since it has the most specific
-    // representation, and will not influence representation inference of the
-    // phi.
-    int continuation_env_length = continuation->last_environment()->length();
-    while (continuation_env_length != from->last_environment()->length()) {
-      if (continuation_env_length > from->last_environment()->length()) {
-        from->last_environment()->Push(graph()->GetConstant0());
-      } else {
-        from->last_environment()->Pop();
-      }
-    }
-  } else {
-    ASSERT(continuation->predecessors()->length() == 0);
-  }
-}
-
-
 HValue* HGraphBuilder::BuildCheckMap(HValue* obj, Handle<Map> map) {
   return Add<HCheckMaps>(obj, map, top_info());
 }
 
 
 HValue* HGraphBuilder::BuildCheckString(HValue* string) {
   if (!string->type().IsString()) {
     ASSERT(!string->IsConstant() ||
            !HConstant::cast(string)->HasStringValue());
     BuildCheckHeapObject(string);
@@ skipping 4396 matching lines @@
     }
 
     if (current_block() != NULL) Goto(join);
     set_current_block(if_false);
   }
 
   // Finish up.  Unconditionally deoptimize if we've handled all the maps we
   // know about and do not want to handle ones we've never seen.  Otherwise
   // use a generic IC.
   if (count == types->length() && FLAG_deoptimize_uncommon_cases) {
-    // Because the deopt may be the only path in the polymorphic load, make sure
-    // that the environment stack matches the depth on deopt that it otherwise
-    // would have had after a successful load.
-    if (!ast_context()->IsEffect()) Push(graph()->GetConstant0());
-    FinishExitWithHardDeoptimization("Uknown map in polymorphic access", join);
+    FinishExitWithHardDeoptimization("Uknown map in polymorphic access");
   } else {
     HInstruction* instr = BuildNamedGeneric(access_type, object, name, value);
     AddInstruction(instr);
     if (!ast_context()->IsEffect()) Push(access_type == LOAD ? instr : value);
 
     if (join != NULL) {
       Goto(join);
     } else {
       Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
       if (!ast_context()->IsEffect()) ast_context()->ReturnValue(Pop());
@@ skipping 701 matching lines @@
     // The caller will use has_side_effects and add a correct Simulate.
     access->SetFlag(HValue::kHasNoObservableSideEffects);
     if (access_type == LOAD) {
       Push(access);
     }
     NoObservableSideEffectsScope scope(this);
     GotoNoSimulate(join);
     set_current_block(other_map);
   }
 
+  // Ensure that we visited at least one map above that goes to join. This is
+  // necessary because FinishExitWithHardDeoptimization does an AbnormalExit
+  // rather than joining the join block. If this becomes an issue, insert a
+  // generic access in the case length() == 0.
+  ASSERT(join->predecessors()->length() > 0);
   // Deopt if none of the cases matched.
   NoObservableSideEffectsScope scope(this);
-  FinishExitWithHardDeoptimization("Unknown map in polymorphic element access",
-                                   join);
+  FinishExitWithHardDeoptimization("Unknown map in polymorphic element access");
   set_current_block(join);
   return access_type == STORE ? NULL : Pop();
 }
 
 
 HValue* HOptimizedGraphBuilder::HandleKeyedElementAccess(
     HValue* obj,
     HValue* key,
     HValue* val,
     Expression* expr,
@@ skipping 467 matching lines @@
     }
 
     if (current_block() != NULL) Goto(join);
     set_current_block(if_false);
   }
 
   // Finish up.  Unconditionally deoptimize if we've handled all the maps we
   // know about and do not want to handle ones we've never seen.  Otherwise
   // use a generic IC.
   if (ordered_functions == types->length() && FLAG_deoptimize_uncommon_cases) {
-    // Because the deopt may be the only path in the polymorphic call, make sure
-    // that the environment stack matches the depth on deopt that it otherwise
-    // would have had after a successful call.
-    Drop(1);  // Drop receiver.
-    if (!ast_context()->IsEffect()) Push(graph()->GetConstant0());
-    FinishExitWithHardDeoptimization("Unknown map in polymorphic call", join);
+    FinishExitWithHardDeoptimization("Unknown map in polymorphic call");
   } else {
     Property* prop = expr->expression()->AsProperty();
     HInstruction* function = BuildNamedGeneric(
         LOAD, receiver, name, NULL, prop->IsUninitialized());
     AddInstruction(function);
     Push(function);
     AddSimulate(prop->LoadId(), REMOVABLE_SIMULATE);
 
     environment()->SetExpressionStackAt(1, function);
     environment()->SetExpressionStackAt(0, receiver);
@@ skipping 4249 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal