Comparison in effect context lazy deopt fix.

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 4357 matching lines @@
 
     // Generate a compare and branch.
     CHECK_ALIVE(VisitForValue(clause->label()));
     HValue* label_value = Pop();
 
     Type* label_type = clause->label()->bounds().lower;
     Type* combined_type = clause->compare_type();
     HControlInstruction* compare = BuildCompareInstruction(
         Token::EQ_STRICT, tag_value, label_value, tag_type, label_type,
         combined_type, stmt->tag()->position(), clause->label()->position(),
-        clause->id());
+        PUSH_BEFORE_SIMULATE, clause->id());
 
     HBasicBlock* next_test_block = graph()->CreateBasicBlock();
     HBasicBlock* body_block = graph()->CreateBasicBlock();
     body_blocks.Add(body_block, zone());
     compare->SetSuccessorAt(0, body_block);
     compare->SetSuccessorAt(1, next_test_block);
     FinishCurrentBlock(compare);
 
     set_current_block(body_block);
     Drop(1);  // tag_value
@@ skipping 5131 matching lines @@
   } else if (op == Token::IN) {
     HValue* function = AddLoadJSBuiltin(Builtins::IN);
     Add<HPushArgument>(left);
     Add<HPushArgument>(right);
     // TODO(olivf) InvokeFunction produces a check for the parameter count,
     // even though we are certain to pass the correct number of arguments here.
     HInstruction* result = New<HInvokeFunction>(function, 2);
     return ast_context()->ReturnInstruction(result, expr->id());
   }
 
+  PushBeforeSimulateBehavior push_behavior =
+    ast_context()->IsEffect() ? NO_PUSH_BEFORE_SIMULATE
+                              : PUSH_BEFORE_SIMULATE;
   HControlInstruction* compare = BuildCompareInstruction(
       op, left, right, left_type, right_type, combined_type,
-      expr->left()->position(), expr->right()->position(), expr->id());
+      expr->left()->position(), expr->right()->position(),
+      push_behavior, expr->id());
   if (compare == NULL) return;  // Bailed out.
   return ast_context()->ReturnControl(compare, expr->id());
 }
 
 
 HControlInstruction* HOptimizedGraphBuilder::BuildCompareInstruction(
     Token::Value op,
     HValue* left,
     HValue* right,
     Type* left_type,
     Type* right_type,
     Type* combined_type,
     int left_position,
     int right_position,
+    PushBeforeSimulateBehavior push_sim_result,
     BailoutId bailout_id) {
   // Cases handled below depend on collected type feedback. They should
   // soft deoptimize when there is no type feedback.
   if (combined_type->Is(Type::None())) {
     Add<HDeoptimize>("Insufficient type feedback for combined type "
                      "of binary operation",
                      Deoptimizer::SOFT);
     combined_type = left_type = right_type = Type::Any(zone());
   }
 
@@ skipping 44 matching lines @@
     Add<HCheckInstanceType>(right, HCheckInstanceType::IS_STRING);
     HStringCompareAndBranch* result =
         New<HStringCompareAndBranch>(left, right, op);
     return result;
   } else {
     if (combined_rep.IsTagged() || combined_rep.IsNone()) {
       HCompareGeneric* result = Add<HCompareGeneric>(left, right, op);
       result->set_observed_input_representation(1, left_rep);
       result->set_observed_input_representation(2, right_rep);
       if (result->HasObservableSideEffects()) {
-        Push(result);
-        AddSimulate(bailout_id, REMOVABLE_SIMULATE);
-        Drop(1);
+        if (push_sim_result == NO_PUSH_BEFORE_SIMULATE) {

[Jakob Kummerow, 2014/02/13 15:55:32]

nit: I'd find it slightly more readable to swap the condition; then you can also
drop the ASSERT (it's clear enough what's going on):

if (push_sim_result == PUSH_BEFORE_SIMULATE) {
  Push(result);
  AddSimulate(bailout_id, REMOVABLE_SIMULATE);
  Drop(1);
} else {
  AddSimulate(bailout_id, REMOVABLE_SIMULATE);
}

+          AddSimulate(bailout_id, REMOVABLE_SIMULATE);
+        } else {
+          ASSERT(push_sim_result == PUSH_BEFORE_SIMULATE);
+          Push(result);
+          AddSimulate(bailout_id, REMOVABLE_SIMULATE);
+          Drop(1);
+        }
       }
       // TODO(jkummerow): Can we make this more efficient?
       HBranch* branch = New<HBranch>(result);
       return branch;
     } else {
       HCompareNumericAndBranch* result =
           New<HCompareNumericAndBranch>(left, right, op);
       result->set_observed_input_representation(left_rep, right_rep);
       if (FLAG_emit_opt_code_positions) {
         result->SetOperandPositions(zone(), left_position, right_position);
@@ skipping 1563 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal