Stabilize escape analysis (without deopt)

src/compiler/escape-analysis-reducer.cc

Index: src/compiler/escape-analysis-reducer.cc
diff --git a/src/compiler/escape-analysis-reducer.cc b/src/compiler/escape-analysis-reducer.cc
index f833ebdf73060aaa86824a0e6a7444bb6fce77e3..d7b79b0733c68e74d756e1bbda623f819ed12de7 100644
--- a/src/compiler/escape-analysis-reducer.cc
+++ b/src/compiler/escape-analysis-reducer.cc
@@ -34,6 +34,8 @@ Reduction EscapeAnalysisReducer::Reduce(Node* node) {
       return ReduceFinishRegion(node);
     case IrOpcode::kReferenceEqual:
       return ReduceReferenceEqual(node);
+    case IrOpcode::kObjectIsSmi:
+      return ReduceObjectIsSmi(node);
     case IrOpcode::kStateValues:
     case IrOpcode::kFrameState:
       return ReplaceWithDeoptDummy(node);
@@ -146,6 +148,20 @@ Reduction EscapeAnalysisReducer::ReduceReferenceEqual(Node* node) {
 }
 
 
+Reduction EscapeAnalysisReducer::ReduceObjectIsSmi(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kObjectIsSmi);
+  Node* input = NodeProperties::GetValueInput(node, 0);
+  if (escape_analysis()->IsAllocation(input)) {

[Michael Starzinger, 2015/12/14 10:41:49]

IIUC, for the escape analysis it would suffice to only do this reduction if
"IsVirtual(input)". So we could limit the reducer to that case and leave the
general optimization (i.e. ObjectIsSmi(Allocate) nodes) to another reducer. Then
we would not need the additional "IsAllocation" function either I think.

[sigurds, 2015/12/14 11:58:09]

Done.

+    ReplaceWithValue(node, jsgraph()->FalseConstant());
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Replaced ObjectIsSmi #%d with false\n", node->id());
+    }
+    return Replace(node);
+  }
+  return NoChange();
+}
+
+
 // TODO(sigurds): This is a temporary solution until escape analysis
 // supports deoptimization.
 Reduction EscapeAnalysisReducer::ReplaceWithDeoptDummy(Node* node) {