Handle holes in smi-untag from LoadKeyed requiring hole handling.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index b6244af4129a3349a7df107922128d18706631c9..b9951ea699e242274357215d103063c01ab6369b 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -5026,14 +5026,26 @@ void LCodeGen::DoSmiTag(LSmiTag* instr) {
 
 void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
   LOperand* input = instr->value();
+  Register result = ToRegister(input);
   ASSERT(input->IsRegister() && input->Equals(instr->result()));
   if (instr->needs_check()) {
-    __ test(ToRegister(input), Immediate(kSmiTagMask));
+    __ test(result, Immediate(kSmiTagMask));
     DeoptimizeIf(not_zero, instr->environment());
+  } else if (instr->hydrogen()->value()->IsLoadKeyed()) {
+    HLoadKeyed* load = HLoadKeyed::cast(instr->hydrogen()->value());
+    if (load->UsesMustHandleHole()) {

[Jakob Kummerow, 2013/05/22 14:06:07]

As discussed offline, I think you need to consider load->hole_mode() as well.

+      Label done;
+      __ test(result, Immediate(kSmiTagMask));
+      __ j(equal, &done);
+      __ xor_(result, result);
+      __ bind(&done);
+    } else {
+      __ AssertSmi(result);
+    }
   } else {
-    __ AssertSmi(ToRegister(input));
+    __ AssertSmi(result);
   }
-  __ SmiUntag(ToRegister(input));
+  __ SmiUntag(result);
 }