Adding assertions to fast elements conversion.

src/x64/codegen-x64.cc

 // Copyright 2011 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 236 matching lines @@
           FieldOperand(r8, r9, times_8, FixedArray::kHeaderSize));
   // r9 : current element's index
   // rbx: current element (smi-tagged)
   __ JumpIfNotSmi(rbx, &convert_hole);
   __ SmiToInteger32(rbx, rbx);
   __ cvtlsi2sd(xmm0, rbx);
   __ movsd(FieldOperand(r14, r9, times_8, FixedDoubleArray::kHeaderSize),
            xmm0);
   __ jmp(&entry);
   __ bind(&convert_hole);
+
+  if (FLAG_debug_code) {
+    Label is_really_the_hole;
+    __ CompareRoot(rbx, Heap::kTheHoleValueRootIndex);
+    __ j(equal, &is_really_the_hole);
+    __ Abort("object found in smi-only array");
+    __ bind(&is_really_the_hole);
+  }
+
   __ movq(FieldOperand(r14, r9, times_8, FixedDoubleArray::kHeaderSize), r15);
   __ bind(&entry);
   __ decq(r9);
   __ j(not_sign, &loop);
 }
 
 
 void ElementsTransitionGenerator::GenerateDoubleToObject(
     MacroAssembler* masm, Label* fail) {
   // ----------- S t a t e -------------
@@ skipping 92 matching lines @@
                       OMIT_SMI_CHECK);
   __ pop(rax);
   __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64