Tiny improvement of register constraints in LClassOfTest instructions.

src/ia32/lithium-codegen-ia32.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 1813 matching lines @@
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   __ test(FieldOperand(input, String::kHashFieldOffset),
           Immediate(String::kContainsCachedArrayIndexMask));
   EmitBranch(true_block, false_block, equal);
 }
 
 
 // Branches to a label or falls through with the answer in the z flag.  Trashes
-// the temp registers, but not the input.  Only input and temp2 may alias.
+// the temp registers, but not the input.
 void LCodeGen::EmitClassOfTest(Label* is_true,
                                Label* is_false,
                                Handle<String>class_name,
                                Register input,
                                Register temp,
                                Register temp2) {
   ASSERT(!input.is(temp));
-  ASSERT(!temp.is(temp2));  // But input and temp2 may be the same register.
+  ASSERT(!input.is(temp2));
+  ASSERT(!temp.is(temp2));
   __ JumpIfSmi(input, is_false);
 
   if (class_name->IsEqualTo(CStrVector("Function"))) {
     // Assuming the following assertions, we can use the same compares to test
     // for both being a function type and being in the object type range.
     STATIC_ASSERT(NUM_OF_CALLABLE_SPEC_OBJECT_TYPES == 2);
     STATIC_ASSERT(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE ==
                   FIRST_SPEC_OBJECT_TYPE + 1);
     STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE ==
                   LAST_SPEC_OBJECT_TYPE - 1);
@@ skipping 39 matching lines @@
   // comparison.
   __ cmp(temp, class_name);
   // End with the answer in the z flag.
 }
 
 
 void LCodeGen::DoClassOfTestAndBranch(LClassOfTestAndBranch* instr) {
   Register input = ToRegister(instr->InputAt(0));
   Register temp = ToRegister(instr->TempAt(0));
   Register temp2 = ToRegister(instr->TempAt(1));
-  if (input.is(temp)) {
-    // Swap.
-    Register swapper = temp;
-    temp = temp2;
-    temp2 = swapper;
-  }
+
   Handle<String> class_name = instr->hydrogen()->class_name();
 
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   Label* true_label = chunk_->GetAssemblyLabel(true_block);
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
   EmitClassOfTest(true_label, false_label, class_name, input, temp, temp2);
 
@@ skipping 2703 matching lines @@
       this, pointers, Safepoint::kLazyDeopt);
   __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32