Refactor translation of short-circuit logical operations to avoid subgraphs.

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 4897 matching lines @@
 
       // Translate right subexpression by visiting it in the same AST
       // context as the entire expression.
       set_current_block(eval_right);
       Visit(expr->right());
 
     } else if (ast_context()->IsValue()) {
       VISIT_FOR_VALUE(expr->left());
       ASSERT(current_block() != NULL);
 
-      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());
-
-      ASSERT(current_block() != NULL &&
-             right_subgraph->exit_block() != NULL);
       // We need an extra block to maintain edge-split form.
       HBasicBlock* empty_block = graph()->CreateBasicBlock();
-      HBasicBlock* join_block = graph()->CreateBasicBlock();
+      HBasicBlock* eval_right = graph()->CreateBasicBlock();
+      HTest* test = is_logical_and
+          ? new HTest(Top(), eval_right, empty_block)
+          : new HTest(Top(), empty_block, eval_right);
+      current_block()->Finish(test);
 
-      HTest* test = is_logical_and
-          ? new HTest(left, right_subgraph->entry_block(), empty_block)
-          : new HTest(left, empty_block, right_subgraph->entry_block());
-      current_block()->Finish(test);
-      empty_block->Goto(join_block);
-      right_subgraph->exit_block()->Goto(join_block);
-      join_block->SetJoinId(expr->id());
+      set_current_block(eval_right);
+      Drop(1);  // Value of the left subexpression.
+      VISIT_FOR_VALUE(expr->right());
+
+      HBasicBlock* join_block =
+          CreateJoin(empty_block, current_block(), expr->id());
       set_current_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);
@@ skipping 1057 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal