Fix loop information computation for floating loops.

src/compiler/scheduler.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <deque>
 #include <queue>
 
 #include "src/compiler/scheduler.h"
 
 #include "src/bit-vector.h"
@@ skipping 745 matching lines @@
             loop = loop->prev;
             // We leave the loop header on the stack; the rest of this iteration
             // and later iterations will go through its outgoing edges list.
           }
 
           // Use the next outgoing edge if there are any.
           int outgoing_index =
               static_cast<int>(frame->index - block->SuccessorCount());
           LoopInfo* info = &loops_[GetLoopNumber(block)];
           DCHECK(loop != info);
-          if (info->outgoing != NULL &&
+          if (block != entry && info->outgoing != NULL &&
               outgoing_index < info->outgoing->length()) {
             succ = info->outgoing->at(outgoing_index);
             frame->index++;
           }
         }
 
         if (succ != NULL) {
           // Process the next successor.
           if (succ->rpo_number() == kBlockOnStack) continue;
           if (succ->rpo_number() == kBlockVisited2) continue;
@@ skipping 87 matching lines @@
       } else {
         Trace("B%d has loop header B%d, (depth == %d)\n", current->id().ToInt(),
               current->loop_header()->id().ToInt(), current->loop_depth());
       }
     }
   }
 
   // Computes loop membership from the backedges of the control flow graph.
   void ComputeLoopInfo(ZoneVector<SpecialRPOStackFrame>& queue,
                        size_t num_loops, ZoneList<Backedge>* backedges) {
+    // Extend existing loop membership vectors.
+    for (LoopInfo& loop : loops_) {
+      BitVector* new_members = new (zone_)
+          BitVector(static_cast<int>(schedule_->BasicBlockCount()), zone_);
+      new_members->CopyFrom(*loop.members);
+      loop.members = new_members;
+    }
+
+    // Extend loop information vector.
     loops_.resize(num_loops, LoopInfo());
 
     // Compute loop membership starting from backedges.
     // O(max(loop_depth) * max(|loop|)
     for (int i = 0; i < backedges->length(); i++) {
       BasicBlock* member = backedges->at(i).first;
       BasicBlock* header = member->SuccessorAt(backedges->at(i).second);
       size_t loop_num = GetLoopNumber(header);
       if (loops_[loop_num].header == NULL) {
         loops_[loop_num].header = header;
@@ skipping 610 matching lines @@
   for (NodeVectorIter i = nodes->begin(); i != nodes->end(); ++i) {
     schedule_->SetBlockForNode(to, *i);
     scheduled_nodes_[to->id().ToSize()].push_back(*i);
   }
   nodes->clear();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8