MIPS: Tiny improvement of register constraints in LClassOfTest instructions.

src/mips/lithium-codegen-mips.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 1844 matching lines @@
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   __ lw(scratch,
          FieldMemOperand(input, String::kHashFieldOffset));
   __ And(at, scratch, Operand(String::kContainsCachedArrayIndexMask));
   EmitBranch(true_block, false_block, eq, at, Operand(zero_reg));
 }
 
 
-// Branches to a label or falls through with this instance class-name adr
-// returned in temp reg, available for comparison by the caller. Trashes the
-// temp registers, but not the input. Only input and temp2 may alias.
+// Branches to a label or falls through with the answer in flags.  Trashes
+// 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 2820 matching lines @@
   ASSERT(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal