Use the macro assembler Set instead of explicit xor for clearing registers.

src/ia32/builtins-ia32.cc

 // Copyright 2010 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 381 matching lines @@
 
 
 void Builtins::Generate_JSConstructStubApi(MacroAssembler* masm) {
   Generate_JSConstructStubHelper(masm, true, false);
 }
 
 
 static void Generate_JSEntryTrampolineHelper(MacroAssembler* masm,
                                              bool is_construct) {
   // Clear the context before we push it when entering the JS frame.
-  __ xor_(esi, Operand(esi));  // clear esi
+  __ Set(esi, Immediate(0));
 
   // Enter an internal frame.
   __ EnterInternalFrame();
 
   // Load the previous frame pointer (ebx) to access C arguments
   __ mov(ebx, Operand(ebp, 0));
 
   // Get the function from the frame and setup the context.
   __ mov(ecx, Operand(ebx, EntryFrameConstants::kFunctionArgOffset));
   __ mov(esi, FieldOperand(ecx, JSFunction::kContextOffset));
 
   // Push the function and the receiver onto the stack.
   __ push(ecx);
   __ push(Operand(ebx, EntryFrameConstants::kReceiverArgOffset));
 
   // Load the number of arguments and setup pointer to the arguments.
   __ mov(eax, Operand(ebx, EntryFrameConstants::kArgcOffset));
   __ mov(ebx, Operand(ebx, EntryFrameConstants::kArgvOffset));
 
   // Copy arguments to the stack in a loop.
   Label loop, entry;
-  __ xor_(ecx, Operand(ecx));  // clear ecx
+  __ Set(ecx, Immediate(0));
   __ jmp(&entry);
   __ bind(&loop);
   __ mov(edx, Operand(ebx, ecx, times_4, 0));  // push parameter from argv
   __ push(Operand(edx, 0));  // dereference handle
   __ inc(Operand(ecx));
   __ bind(&entry);
   __ cmp(ecx, Operand(eax));
   __ j(not_equal, &loop);
 
   // Get the function from the stack and call it.
@@ skipping 202 matching lines @@
     __ jmp(&shift_arguments);
   }
 
   // 3b. Patch the first argument when calling a non-function.  The
   //     CALL_NON_FUNCTION builtin expects the non-function callee as
   //     receiver, so overwrite the first argument which will ultimately
   //     become the receiver.
   __ bind(&non_function);
   __ mov(Operand(esp, eax, times_4, 0), edi);
   // Clear edi to indicate a non-function being called.
-  __ xor_(edi, Operand(edi));
+  __ Set(edi, Immediate(0));
 
   // 4. Shift arguments and return address one slot down on the stack
   //    (overwriting the original receiver).  Adjust argument count to make
   //    the original first argument the new receiver.
   __ bind(&shift_arguments);
   { Label loop;
     __ mov(ecx, eax);
     __ bind(&loop);
     __ mov(ebx, Operand(esp, ecx, times_4, 0));
     __ mov(Operand(esp, ecx, times_4, kPointerSize), ebx);
     __ dec(ecx);
     __ j(not_sign, &loop);  // While non-negative (to copy return address).
     __ pop(ebx);  // Discard copy of return address.
     __ dec(eax);  // One fewer argument (first argument is new receiver).
   }
 
   // 5a. Call non-function via tail call to CALL_NON_FUNCTION builtin.
   { Label function;
     __ test(edi, Operand(edi));
     __ j(not_zero, &function, taken);
-    __ xor_(ebx, Operand(ebx));
+    __ Set(ebx, Immediate(0));
     __ GetBuiltinEntry(edx, Builtins::CALL_NON_FUNCTION);
     __ jmp(Handle<Code>(builtin(ArgumentsAdaptorTrampoline)),
            RelocInfo::CODE_TARGET);
     __ bind(&function);
   }
 
   // 5b. Get the code to call from the function and check that the number of
   //     expected arguments matches what we're providing.  If so, jump
   //     (tail-call) to the code in register edx without checking arguments.
   __ mov(edx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
@@ skipping 887 matching lines @@
   Deoptimizer::EntryGenerator generator(masm, Deoptimizer::OSR);
   generator.Generate();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32