Allow control intructions to have side effects.

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 2612 matching lines @@
   ASSERT(!instr->IsControlInstruction());
   owner()->AddInstruction(instr);
   if (instr->HasObservableSideEffects()) {
     owner()->Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
   }
 }
 
 
 void EffectContext::ReturnControl(HControlInstruction* instr,
                                   BailoutId ast_id) {
-  ASSERT(!instr->HasObservableSideEffects());
+  // We can ignore ObservableSideEffects here since CreateJoin will add

[titzer, 2013/09/19 16:24:27]

I find this comment confusing and would rather just leave it out.

[oliv, 2013/09/19 16:38:00]

Done.

+  // Simulates anyway.
   HBasicBlock* empty_true = owner()->graph()->CreateBasicBlock();
   HBasicBlock* empty_false = owner()->graph()->CreateBasicBlock();
   instr->SetSuccessorAt(0, empty_true);
   instr->SetSuccessorAt(1, empty_false);
   owner()->current_block()->Finish(instr);
   HBasicBlock* join = owner()->CreateJoin(empty_true, empty_false, ast_id);
   owner()->set_current_block(join);
 }
 
 
@@ skipping 20 matching lines @@
   }
   owner()->AddInstruction(instr);
   owner()->Push(instr);
   if (instr->HasObservableSideEffects()) {
     owner()->Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
   }
 }
 
 
 void ValueContext::ReturnControl(HControlInstruction* instr, BailoutId ast_id) {
-  ASSERT(!instr->HasObservableSideEffects());
+  // We can ignore ObservableSideEffects here since CreateJoin will add
+  // Simulates anyway.
   if (!arguments_allowed() && instr->CheckFlag(HValue::kIsArguments)) {
     return owner()->Bailout(kBadValueContextForArgumentsObjectValue);
   }
   HBasicBlock* materialize_false = owner()->graph()->CreateBasicBlock();
   HBasicBlock* materialize_true = owner()->graph()->CreateBasicBlock();
   instr->SetSuccessorAt(0, materialize_true);
   instr->SetSuccessorAt(1, materialize_false);
   owner()->current_block()->Finish(instr);
   owner()->set_current_block(materialize_true);
   owner()->Push(owner()->graph()->GetConstantTrue());
@@ skipping 37 matching lines @@
   if (instr->HasObservableSideEffects()) {
     builder->Push(instr);
     builder->Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
     builder->Pop();
   }
   BuildBranch(instr);
 }
 
 
 void TestContext::ReturnControl(HControlInstruction* instr, BailoutId ast_id) {
-  ASSERT(!instr->HasObservableSideEffects());
+  // We can ignore ObservableSideEffects here since both HGoto instructions
+  // insert a different Simulate, thus we will directly deoptimize into the
+  // correct branch.
   HBasicBlock* empty_true = owner()->graph()->CreateBasicBlock();
   HBasicBlock* empty_false = owner()->graph()->CreateBasicBlock();
   instr->SetSuccessorAt(0, empty_true);
   instr->SetSuccessorAt(1, empty_false);
   owner()->current_block()->Finish(instr);
   empty_true->Goto(if_true(), owner()->function_state());
   empty_false->Goto(if_false(), owner()->function_state());
   owner()->set_current_block(NULL);
 }
 
@@ skipping 5294 matching lines @@
     BuildCheckHeapObject(left);
     AddInstruction(HCheckInstanceType::NewIsInternalizedString(left, zone()));
     BuildCheckHeapObject(right);
     AddInstruction(HCheckInstanceType::NewIsInternalizedString(right, zone()));
     HCompareObjectEqAndBranch* result =
         New<HCompareObjectEqAndBranch>(left, right);
     result->set_position(expr->position());
     return ast_context()->ReturnControl(result, expr->id());
   } else {
     if (combined_rep.IsTagged() || combined_rep.IsNone()) {
-      HCompareGeneric* result =
-          new(zone()) HCompareGeneric(context, left, right, op);
-      result->set_observed_input_representation(1, left_rep);
-      result->set_observed_input_representation(2, right_rep);
+      HCompareGenericAndBranch* result =
+          New<HCompareGenericAndBranch>(left, right, op);
+      result->set_observed_input_representation(left_rep, right_rep);
       result->set_position(expr->position());
-      return ast_context()->ReturnInstruction(result, expr->id());
+      return ast_context()->ReturnControl(result, expr->id());
     } else {
       HCompareNumericAndBranch* result =
           New<HCompareNumericAndBranch>(left, right, op);
       result->set_observed_input_representation(left_rep, right_rep);
       result->set_position(expr->position());
       return ast_context()->ReturnControl(result, expr->id());
     }
   }
 }
 
@@ skipping 1553 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal