VM: Avoid smi-check when loading class-ids from known non-smi values

runtime/vm/intermediate_language_mips.cc

Index: runtime/vm/intermediate_language_mips.cc
diff --git a/runtime/vm/intermediate_language_mips.cc b/runtime/vm/intermediate_language_mips.cc
index a8595a829c0621735336b8d889473ede41011d44..7bbfb552f7563eb588d89a8ba90245d71e9cb535 100644
--- a/runtime/vm/intermediate_language_mips.cc
+++ b/runtime/vm/intermediate_language_mips.cc
@@ -1135,7 +1135,14 @@ LocationSummary* LoadClassIdInstr::MakeLocationSummary(Zone* zone,
 void LoadClassIdInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register object = locs()->in(0).reg();
   Register result = locs()->out(0).reg();
-  __ LoadTaggedClassIdMayBeSmi(result, object);
+  const AbstractType& value_type = *this->object()->Type()->ToAbstractType();
+  if (CompileType::Smi().IsAssignableTo(value_type) ||
+      value_type.IsTypeParameter()) {
+    __ LoadTaggedClassIdMayBeSmi(result, object);
+  } else {
+    __ LoadClassId(result, object);
+    __ SmiTag(result);
+  }
 }