Allow IfBuilder's to join existing (captured) continuations.

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 786 matching lines @@
       : last_true_block_;
   HBasicBlock* false_block = did_else_ && (first_false_block_ != NULL)
       ? builder_->current_block()
       : first_false_block_;
   continuation->Capture(true_block, false_block, position_);
   captured_ = true;
   End();
 }
 
 
+void HGraphBuilder::IfBuilder::JoinContinuation(HIfContinuation* continuation) {
+  ASSERT(!finished_);
+  ASSERT(!captured_);
+  HBasicBlock* true_block = last_true_block_ == NULL
+      ? first_true_block_
+      : last_true_block_;
+  HBasicBlock* false_block = did_else_ && (first_false_block_ != NULL)
+      ? builder_->current_block()
+      : first_false_block_;
+  if (true_block != NULL && !true_block->IsFinished()) {
+    ASSERT(continuation->IsTrueReachable());
+    true_block->GotoNoSimulate(continuation->true_branch());
+  }
+  if (false_block != NULL && !false_block->IsFinished()) {
+    ASSERT(continuation->IsFalseReachable());
+    false_block->GotoNoSimulate(continuation->false_branch());
+  }
+  captured_ = true;
+  End();
+}
+
+
 void HGraphBuilder::IfBuilder::Then() {
   ASSERT(!captured_);
   ASSERT(!finished_);
   did_then_ = true;
   if (needs_compare_) {
     // Handle if's without any expressions, they jump directly to the "else"
     // branch. However, we must pretend that the "then" branch is reachable,
     // so that the graph builder visits it and sees any live range extending
     // constructs within it.
     HConstant* constant_false = builder_->graph()->GetConstantFalse();
@@ skipping 8816 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal