Range info propagation through HBoundsCheck.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index e816471ce604561601f90dfd08f41e25ed3d7495..c47126cf7241db445429b151f169ab33dade6d92 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -947,6 +947,25 @@ void HBoundsCheck::InferRepresentation(HInferRepresentationPhase* h_infer) {
 }
 
 
+Range* HBoundsCheck::InferRange(Zone* zone) {
+  Representation r = representation();
+  if (r.IsSmiOrInteger32() && length()->HasRange()) {
+    int upper = length()->range()->upper() - (allow_equality() ? 0 : 1);
+    int lower = 0;
+
+    Range* result = new(zone) Range(lower, upper);
+    if (index()->HasRange()) {
+      result->Intersect(index()->range());
+    }
+
+    // In case of Smi representation, clamp result to Smi::kMaxValue.
+    if (r.IsSmi()) result->ClampToSmi();
+    return result;
+  }
+  return HValue::InferRange(zone);
+}
+
+
 void HBoundsCheckBaseIndexInformation::PrintDataTo(StringStream* stream) {
   stream->Add("base: ");
   base_index()->PrintNameTo(stream);