Use cmov instructions to avoid some conditional branches in stub code....

src/ia32/stub-cache-ia32.cc

 // Copyright 2006-2009 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 1882 matching lines @@
   __ mov(edi, Factory::undefined_value());
 
   // eax: argc
   // ecx: first argument
   // edx: first in-object property of the JSObject
   // edi: undefined
   // Fill the initialized properties with a constant value or a passed argument
   // depending on the this.x = ...; assignment in the function.
   for (int i = 0; i < shared->this_property_assignments_count(); i++) {
     if (shared->IsThisPropertyAssignmentArgument(i)) {
-      Label not_passed;
-      // Set the property to undefined.
-      __ mov(Operand(edx, i * kPointerSize), edi);
       // Check if the argument assigned to the property is actually passed.
+      // If argument is not passed the property is set to undefined,
+      // otherwise find it on the stack.
       int arg_number = shared->GetThisPropertyAssignmentArgument(i);
+      __ mov(ebx, edi);
       __ cmp(eax, arg_number);
-      __ j(below_equal, &not_passed);
-      // Argument passed - find it on the stack.
-      __ mov(ebx, Operand(ecx, arg_number * -kPointerSize));
+      if (CpuFeatures::IsSupported(CMOV)) {
+        CpuFeatures::Scope use_cmov(CMOV);
+        __ cmov(above, ebx, Operand(ecx, arg_number * -kPointerSize));
+      } else {
+        Label not_passed;
+        __ j(below_equal, &not_passed);
+        __ mov(ebx, Operand(ecx, arg_number * -kPointerSize));
+        __ bind(&not_passed);
+      }
+      // Store value in the property.
       __ mov(Operand(edx, i * kPointerSize), ebx);
-      __ bind(&not_passed);
     } else {
       // Set the property to the constant value.
       Handle<Object> constant(shared->GetThisPropertyAssignmentConstant(i));
       __ mov(Operand(edx, i * kPointerSize), Immediate(constant));
     }
   }
 
   // Fill the unused in-object property fields with undefined.
   for (int i = shared->this_property_assignments_count();
        i < shared->CalculateInObjectProperties();
@@ skipping 22 matching lines @@
   __ jmp(generic_construct_stub, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal