Fix -O0 compilation errors

runtime/vm/intermediate_language_mips.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/compiler.h"
@@ skipping 1760 matching lines @@
     summary->set_in(0, Location::RequiresRegister());
     // We need temporaries for field object.
     summary->set_temp(0, Location::RequiresRegister());
     return summary;
   } else {
     LocationSummary* summary = new(zone) LocationSummary(
         zone, kNumInputs, 0, LocationSummary::kNoCall);
     summary->set_in(0, Location::RequiresRegister());
     return summary;
   }
   UNREACHABLE();

[Florian Schneider, 2016/08/29 21:44:06]

I wonder if removing the UNREACHABLE would also fix it. It does not make sense
anyway after the else-clause.

Or even remove the else-clause as well, and write instead:

if (...) {
  ...
  return x;
}
...
return y;

[zra, 2016/08/29 21:57:30]

removed else

+  return NULL;
 }
 
 
 void GuardFieldLengthInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (field().guarded_list_length() == Field::kNoFixedLength) {
     if (Compiler::IsBackgroundCompilation()) {
       // Field state changed while compiling.
       Compiler::AbortBackgroundCompilation(deopt_id(),
           "GuardFieldLengthInstr: field state changed while compiling");
     }
@@ skipping 3990 matching lines @@
                                 1,
                                 locs());
   __ lw(result, Address(SP, 1 * kWordSize));
   __ addiu(SP, SP, Immediate(2 * kWordSize));
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS