VM-codegen: Add IL instruction to check if a Smi is in a constant range

runtime/vm/constant_propagator.cc

Index: runtime/vm/constant_propagator.cc
diff --git a/runtime/vm/constant_propagator.cc b/runtime/vm/constant_propagator.cc
index dec674c2c1171f78b4ea6b7407af9d611738bdf8..9a5be2a76ee621860ffc042344ab1f990fc0d870 100644
--- a/runtime/vm/constant_propagator.cc
+++ b/runtime/vm/constant_propagator.cc
@@ -431,6 +431,24 @@ void ConstantPropagator::VisitIfThenElse(IfThenElseInstr* instr) {
 }
 
 
+void ConstantPropagator::VisitSmiRangeComparison(
+    SmiRangeComparisonInstr* instr) {
+  Definition* defn = instr->input()->definition();
+  const Object& value = defn->constant_value();
+  if (IsConstant(value)) {
+    ASSERT(value.IsSmi());
+    intptr_t number = Smi::Cast(value).Value();
+    if (number < instr->from() || instr->to() < number) {

[Vyacheslav Egorov (Google), 2017/06/28 13:53:47]

maybe better:

bool result = instr->from() <= number && number < instr->to();
if (instr->is_negated()) { result = !result; }

SetValue(instr, Bool::Get(result));

[erikcorry, 2017/07/03 08:59:55]

Done, but with <= because to() is inclusive.

+      SetValue(instr, Bool::Get(instr->is_negated()));
+    } else {
+      SetValue(instr, Bool::Get(!instr->is_negated()));
+    }
+  } else if (IsNonConstant(value)) {
+    SetValue(instr, non_constant_);
+  }
+}
+
+
 void ConstantPropagator::VisitStrictCompare(StrictCompareInstr* instr) {
   Definition* left_defn = instr->left()->definition();
   Definition* right_defn = instr->right()->definition();