Fix a bug in deoptimization after logical expressions in an effect context.

src/hydrogen.cc

 // Copyright 2011 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 464 matching lines @@
 HConstant* HGraph::GetConstantTrue() {
   return GetConstant(&constant_true_, Heap::true_value());
 }
 
 
 HConstant* HGraph::GetConstantFalse() {
   return GetConstant(&constant_false_, Heap::false_value());
 }
 
 
-void HSubgraph::AppendOptional(HSubgraph* graph,
-                               bool on_true_branch,
-                               HValue* value) {
-  ASSERT(HasExit() && graph->HasExit());
-  HBasicBlock* other_block = graph_->CreateBasicBlock();
-  HBasicBlock* join_block = graph_->CreateBasicBlock();
-
-  HTest* test = on_true_branch
-      ? new HTest(value, graph->entry_block(), other_block)
-      : new HTest(value, other_block, graph->entry_block());
-  exit_block_->Finish(test);
-  other_block->Goto(join_block);
-  graph->exit_block()->Goto(join_block);
-  exit_block_ = join_block;
-}
-
-
 void HSubgraph::AppendJoin(HSubgraph* then_graph,
                            HSubgraph* else_graph,
                            AstNode* node) {
   if (then_graph->HasExit() && else_graph->HasExit()) {
     // We need to merge, create new merge block.
     HBasicBlock* join_block = graph_->CreateBasicBlock();
     then_graph->exit_block()->Goto(join_block);
     else_graph->exit_block()->Goto(join_block);
     join_block->SetJoinId(node->id());
     exit_block_ = join_block;
@@ skipping 4458 matching lines @@
       } else {
         VISIT_FOR_CONTROL(expr->left(), context->if_true(), eval_right);
       }
       eval_right->SetJoinId(expr->RightId());
 
       // Translate right subexpression by visiting it in the same AST
       // context as the entire expression.
       subgraph()->set_exit_block(eval_right);
       Visit(expr->right());
 
-    } else {
+    } else if (ast_context()->IsValue()) {
       VISIT_FOR_VALUE(expr->left());
       ASSERT(current_subgraph_->HasExit());
 
       HValue* left = Top();
       HEnvironment* environment_copy = environment()->Copy();
       environment_copy->Pop();
       HSubgraph* right_subgraph;
       right_subgraph = CreateBranchSubgraph(environment_copy);
       ADD_TO_SUBGRAPH(right_subgraph, expr->right());
-      current_subgraph_->AppendOptional(right_subgraph, is_logical_and, left);
-      current_subgraph_->exit_block()->SetJoinId(expr->id());
+
+      ASSERT(subgraph()->HasExit() && right_subgraph->HasExit());
+      // We need an extra block to maintain edge-split form.
+      HBasicBlock* empty_block = graph()->CreateBasicBlock();
+      HBasicBlock* join_block = graph()->CreateBasicBlock();
+
+      HTest* test = is_logical_and
+          ? new HTest(left, right_subgraph->entry_block(), empty_block)
+          : new HTest(left, empty_block, right_subgraph->entry_block());
+      subgraph()->exit_block()->Finish(test);
+      empty_block->Goto(join_block);
+      right_subgraph->exit_block()->Goto(join_block);
+      join_block->SetJoinId(expr->id());
+      subgraph()->set_exit_block(join_block);
       ast_context()->ReturnValue(Pop());
+    } else {
+      ASSERT(ast_context()->IsEffect());
+      // In an effect context, we don't need the value of the left
+      // subexpression, only its control flow and side effects.  We need an
+      // extra block to maintain edge-split form.
+      HBasicBlock* empty_block = graph()->CreateBasicBlock();
+      HBasicBlock* right_block = graph()->CreateBasicBlock();
+      HBasicBlock* join_block = graph()->CreateBasicBlock();
+      if (is_logical_and) {
+        VISIT_FOR_CONTROL(expr->left(), right_block, empty_block);
+      } else {
+        VISIT_FOR_CONTROL(expr->left(), empty_block, right_block);
+      }
+      // TODO(kmillikin): Find a way to fix this.  It's ugly that there are
+      // actually two empty blocks (one here and one inserted by
+      // TestContext::BuildBranch, and that they both have an HSimulte

[Mads Ager (chromium), 2011/02/17 10:35:34]

HSimulte -> HSimulate.

[Kevin Millikin (Chromium), 2011/02/17 11:05:42]

Thanks.

+      // though the second one is not a merge node, and that we really have
+      // no good AST ID to put on that first HSimulate.
+      empty_block->SetJoinId(expr->id());
+      right_block->SetJoinId(expr->RightId());
+      subgraph()->set_exit_block(right_block);
+      VISIT_FOR_EFFECT(expr->right());
+
+      empty_block->Goto(join_block);
+      subgraph()->exit_block()->Goto(join_block);
+      join_block->SetJoinId(expr->id());
+      subgraph()->set_exit_block(join_block);
+      // We did not materialize any value in the predecessor environments,
+      // so there is no need to handle it here.
     }
 
   } else {
     VISIT_FOR_VALUE(expr->left());
     VISIT_FOR_VALUE(expr->right());
 
     HValue* right = Pop();
     HValue* left = Pop();
     HInstruction* instr = BuildBinaryOperation(expr, left, right);
     instr->set_position(expr->position());
@@ skipping 1010 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal