MIPS: Let the register allocator handle the context register.

src/mips/macro-assembler-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 230 matching lines @@
 // tag is shifted away.
 void MacroAssembler::RecordWrite(Register object,
                                  Register address,
                                  Register value,
                                  RAStatus ra_status,
                                  SaveFPRegsMode fp_mode,
                                  RememberedSetAction remembered_set_action,
                                  SmiCheck smi_check) {
   ASSERT(!AreAliased(object, address, value, t8));
   ASSERT(!AreAliased(object, address, value, t9));
-  // The compiled code assumes that record write doesn't change the
-  // context register, so we check that none of the clobbered
-  // registers are cp.
-  ASSERT(!address.is(cp) && !value.is(cp));
 
   if (emit_debug_code()) {
     lw(at, MemOperand(address));
     Assert(
         eq, kWrongAddressOrValuePassedToRecordWrite, at, Operand(value));
   }
 
   Label done;
 
   if (smi_check == INLINE_SMI_CHECK) {
@@ skipping 5426 matching lines @@
        opcode == BGTZL);
   opcode = (cond == eq) ? BEQ : BNE;
   instr = (instr & ~kOpcodeMask) | opcode;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS