Eliminate redundant smi checks

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 8f10008e88d933cf82c2beb77947f7b33510bffb..38641874b6c3c45f0df0ed9d5eb4bde77bf3ec03 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -2753,9 +2753,14 @@ void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
 
   // Check for the hole value.
   if (instr->hydrogen()->RequiresHoleCheck()) {
-    __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
-    __ cmp(result, scratch);
-    DeoptimizeIf(eq, instr->environment());
+    if (IsFastSmiElementsKind(instr->hydrogen()->elements_kind())) {
+      __ tst(result, Operand(kSmiTagMask));
+      DeoptimizeIf(ne, instr->environment());
+    } else {
+      __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
+      __ cmp(result, scratch);
+      DeoptimizeIf(eq, instr->environment());
+    }
   }
 }