[turbofan] Sparse representation for state values

src/compiler/liveness-analyzer.cc

Index: src/compiler/liveness-analyzer.cc
diff --git a/src/compiler/liveness-analyzer.cc b/src/compiler/liveness-analyzer.cc
index 0cf13332f4e8240de629eb7a13df71f908a60e21..b38708eb4b8ed78c699dac1ae0e9c04c1e874695 100644
--- a/src/compiler/liveness-analyzer.cc
+++ b/src/compiler/liveness-analyzer.cc
@@ -149,8 +149,8 @@ void NonLiveFrameStateSlotReplacer::ClearNonLiveFrameStateSlots(
         static_cast<int>(StateValuesAccess(frame_state->InputAt(2)).size()), 1);
     int index = liveness->length() - 1;
     if (!liveness->Contains(index) && !permanently_live_.Contains(index)) {
-      Node* new_value =
-          state_values_cache()->GetNodeForValues(&replacement_node_, 1);
+      Node* new_value = state_values_cache()->GetNodeForValues(
+          &replacement_node_, 1, nullptr);

[Jarin, 2016/12/07 08:56:20]

How about adding a default value (nullptr) for the liveness? This nullptr here
is a bit confusing.

[Leszek Swirski, 2016/12/08 15:44:30]

Ah, I had that originally but forgot to add it back in after some refactoring.
Done.

       frame_state->ReplaceInput(2, new_value);
     }
   }
@@ -176,7 +176,7 @@ Node* NonLiveFrameStateSlotReplacer::ClearNonLiveStateValues(
 
   Node* result = state_values_cache()->GetNodeForValues(
       inputs_buffer_.empty() ? nullptr : &(inputs_buffer_.front()),
-      inputs_buffer_.size());
+      inputs_buffer_.size(), nullptr);
   inputs_buffer_.clear();
   return result;
 }