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

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4592 matching lines @@
 void LCodeGen::DoSmiUntag(LSmiUntag* instr) {
   Register scratch = scratch0();
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
   if (instr->needs_check()) {
     STATIC_ASSERT(kHeapObjectTag == 1);
     // If the input is a HeapObject, value of scratch won't be zero.
     __ And(scratch, input, Operand(kHeapObjectTag));
     __ SmiUntag(result, input);
     DeoptimizeIf(ne, instr->environment(), scratch, Operand(zero_reg));
+  } else if (instr->hydrogen()->value()->IsLoadKeyed()) {
+    HLoadKeyed* load = HLoadKeyed::cast(instr->hydrogen()->value());
+    if (load->UsesMustHandleHole()) {
+      __ And(scratch, input, Operand(kHeapObjectTag));
+      __ SmiUntag(result, input);
+      if (load->hole_mode() == ALLOW_RETURN_HOLE) {
+        Label done;
+        __ Branch(&done, eq, scratch, Operand(zero_reg));
+        __ li(result, Operand(Smi::FromInt(0)));
+        __ bind(&done);
+      } else {
+        DeoptimizeIf(ne, instr->environment(), scratch, Operand(zero_reg));
+      }
+    } else {
+      __ SmiUntag(result, input);
+    }
   } else {
     __ SmiUntag(result, input);
   }
 }
 
 
 void LCodeGen::EmitNumberUntagD(Register input_reg,
                                 DoubleRegister result_reg,
                                 bool deoptimize_on_undefined,
                                 bool deoptimize_on_minus_zero,
@@ skipping 1034 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal