Abcd for performance check.

src/hydrogen.cc

 // Copyright 2012 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 419 matching lines @@
 }
 #endif
 
 
 void HLoopInformation::RegisterBackEdge(HBasicBlock* block) {
   this->back_edges_.Add(block, block->zone());
   AddBlock(block);
 }
 
 
+void HLoopInformation::ProcessEdge(HBasicBlock* destination) {
+  HLoopInformation* target_loop = destination->current_loop();
+  if (IsInThisLoop(target_loop)) return;
+
+  HLoopInformation* current_loop = this;
+  while (current_loop != NULL) {
+    if (target_loop == current_loop) return;
+    current_loop->exits_count_++;
+    current_loop = current_loop->parent_loop();
+  }
+}
+
+
+void HLoopInformation::ProcessThrow() {
+  HLoopInformation* current_loop = this;
+  while (current_loop != NULL) {

[Jakob Kummerow, 2013/04/17 11:34:15]

Please add a comment saying that when we support try..catch in crankshaft, we
need another condition here: break the while-loop when encountering the catch
block. From a correctness PoV we're safe anyway, but unnecessarily marking loops
as having additional exits could prevent BCE.

[Massi, 2013/05/07 11:32:03]

Done.

+    current_loop->exits_count_++;
+    current_loop = current_loop->parent_loop();
+  }
+}
+
+
 HBasicBlock* HLoopInformation::GetLastBackEdge() const {
   int max_id = -1;
   HBasicBlock* result = NULL;
   for (int i = 0; i < back_edges_.length(); ++i) {
     HBasicBlock* cur = back_edges_[i];
     if (cur->block_id() > max_id) {
       max_id = cur->block_id();
       result = cur;
     }
   }
@@ skipping 1560 matching lines @@
       PostorderProcessor::CreateEntryProcessor(zone(), start, &visited);
   while (postorder != NULL) {
     postorder = postorder->PerformStep(zone(), &visited, &reverse_result);
   }
   blocks_.Rewind(0);
   int index = 0;
   for (int i = reverse_result.length() - 1; i >= 0; --i) {
     HBasicBlock* b = reverse_result[i];
     blocks_.Add(b, zone());
     b->set_block_id(index++);
+
+    HLoopInformation* loop = b->current_loop();
+    if (loop != NULL) {
+      for (int i = 0; i < b->end()->SuccessorCount(); i++) {
+        HBasicBlock* successor = b->end()->SuccessorAt(i);
+        loop->ProcessEdge(successor);
+      }
+    }
   }
 }
 
 
 void HGraph::AssignDominators() {
   HPhase phase("H_Assign dominators", this);
   for (int i = 0; i < blocks_.length(); ++i) {
     HBasicBlock* block = blocks_[i];
     if (block->IsLoopHeader()) {
       // Only the first predecessor of a loop header is from outside the loop.
@@ skipping 1376 matching lines @@
       if (phi->representation().IsNone()) {
         phi->ChangeRepresentation(Representation::Tagged());
       }
     }
     for (HInstruction* current = block->first();
          current != NULL; current = current->next()) {
       if (current->representation().IsNone() &&
           current->CheckFlag(HInstruction::kFlexibleRepresentation)) {
         current->ChangeRepresentation(Representation::Tagged());
       }
+
+      if (current->IsThrow()) {

[Jakob Kummerow, 2013/04/17 11:34:15]

Let's move this into the block ordering phase where ProcessEdge is called too.

[Massi, 2013/05/07 11:32:03]

Done.

+        if (block->current_loop() != NULL) {
+          block->current_loop()->ProcessThrow();
+        }
+      }
     }
   }
 }
 
 
 void HGraph::MergeRemovableSimulates() {
   ZoneList<HSimulate*> mergelist(2, zone());
   for (int i = 0; i < blocks()->length(); ++i) {
     HBasicBlock* block = blocks()->at(i);
     // Make sure the merge list is empty at the start of a block.
@@ skipping 8240 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal