[simulator] remove unused argument field for stop/breaks.

src/mips64/assembler-mips64.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 2247 matching lines @@
           code <= kMaxStopCode &&
           code > kMaxWatchpointCode) ||
          (!break_as_stop &&
           (code > kMaxStopCode ||
            code <= kMaxWatchpointCode)));
   Instr break_instr = SPECIAL | BREAK | (code << 6);
   emit(break_instr);
 }
 
 
 void Assembler::stop(const char* msg, uint32_t code) {

[petermarshall, 2017/03/09 11:37:35]

msg is no longer used at all - could it be removed too? There seem to be a lot
of callers that still provide a msg, but it is totally ignored. It could be
confusing to someone running/debugging the code who expects to see the msg
output somewhere.

   DCHECK(code > kMaxWatchpointCode);
   DCHECK(code <= kMaxStopCode);
 #if defined(V8_HOST_ARCH_MIPS) || defined(V8_HOST_ARCH_MIPS64)
   break_(0x54321);
 #else  // V8_HOST_ARCH_MIPS
   BlockTrampolinePoolFor(3);
-  // The Simulator will handle the stop instruction and get the message address.
-  // On MIPS stop() is just a special kind of break_().
   break_(code, true);
-  // Do not embed the message string address! We used to do this, but that
-  // made snapshots created from position-independent executable builds
-  // non-deterministic.
-  // TODO(yangguo): remove this field entirely.
-  nop();
 #endif
 }
 
 
 void Assembler::tge(Register rs, Register rt, uint16_t code) {
   DCHECK(is_uint10(code));
   Instr instr = SPECIAL | TGE | rs.code() << kRsShift
       | rt.code() << kRtShift | code << 6;
   emit(instr);
 }
@@ skipping 1239 matching lines @@
 
   if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
     Assembler::FlushICache(isolate, pc, 4 * Assembler::kInstrSize);
   }
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64