Ensure that GenerateStoreFastDoubleElement returns stored value on all paths.

src/ia32/stub-cache-ia32.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 3963 matching lines @@
   if (CpuFeatures::IsSupported(SSE2)) {
     CpuFeatures::Scope use_sse2(SSE2);
     __ movdbl(xmm0, Operand::StaticVariable(canonical_nan_reference));
   } else {
     __ fld_d(Operand::StaticVariable(canonical_nan_reference));
   }
   __ jmp(&have_double_value, Label::kNear);
 
   __ bind(&smi_value);
   // Value is a smi. convert to a double and store.
-  __ SmiUntag(eax);
-  __ push(eax);
+  // Preserve original value.
+  __ mov(edx, eax);
+  __ SmiUntag(edx);
+  __ push(edx);
   __ fild_s(Operand(esp, 0));
-  __ pop(eax);
+  __ pop(edx);
   __ fstp_d(FieldOperand(edi, ecx, times_4, FixedDoubleArray::kHeaderSize));
   __ ret(0);
 
   // Handle store cache miss, replacing the ic with the generic stub.
   __ bind(&miss_force_generic);
   Handle<Code> ic_force_generic =
       masm->isolate()->builtins()->KeyedStoreIC_MissForceGeneric();
   __ jmp(ic_force_generic, RelocInfo::CODE_TARGET);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32