Fixes a bug in the mips Random_nextState intrinsic.

runtime/vm/simulator_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 <math.h>  // for isnan.
 #include <setjmp.h>
 #include <stdlib.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_MIPS)
@@ skipping 1376 matching lines @@
 void Simulator::DecodeSpecial2(Instr* instr) {
   ASSERT(instr->OpcodeField() == SPECIAL2);
   switch (instr->FunctionField()) {
     case MADD: {
       ASSERT(instr->RdField() == 0);
       ASSERT(instr->SaField() == 0);
       // Format(instr, "madd 'rs, 'rt");
       uint32_t lo = get_lo_register();
       int32_t hi = get_hi_register();
       int64_t accum = Utils::LowHighTo64Bits(lo, hi);
-      int64_t rs = static_cast<int64_t>(get_register(instr->RsField()));
-      int64_t rt = static_cast<int64_t>(get_register(instr->RtField()));
+      int64_t rs = get_register(instr->RsField());
+      int64_t rt = get_register(instr->RtField());
       int64_t res = accum + rs * rt;
       set_hi_register(Utils::High32Bits(res));
       set_lo_register(Utils::Low32Bits(res));
       break;
     }
     case MADDU: {
       ASSERT(instr->RdField() == 0);
       ASSERT(instr->SaField() == 0);
       // Format(instr, "maddu 'rs, 'rt");
       uint32_t lo = get_lo_register();
       uint32_t hi = get_hi_register();
       uint64_t accum = Utils::LowHighTo64Bits(lo, hi);
-      uint64_t rs = static_cast<uint64_t>(get_register(instr->RsField()));
-      uint64_t rt = static_cast<uint64_t>(get_register(instr->RtField()));
+      uint64_t rs = static_cast<uint32_t>(get_register(instr->RsField()));
+      uint64_t rt = static_cast<uint32_t>(get_register(instr->RtField()));
       uint64_t res = accum + rs * rt;
       set_hi_register(Utils::High32Bits(res));
       set_lo_register(Utils::Low32Bits(res));
       break;
     }
     case CLO: {
       ASSERT(instr->SaField() == 0);
       ASSERT(instr->RtField() == instr->RdField());
       // Format(instr, "clo 'rd, 'rs");
       int32_t rs_val = get_register(instr->RsField());
@@ skipping 805 matching lines @@
   set_register(kExceptionObjectReg, bit_cast<int32_t>(raw_exception));
   set_register(kStackTraceObjectReg, bit_cast<int32_t>(raw_stacktrace));
   buf->Longjmp();
 }
 
 }  // namespace dart
 
 #endif  // !defined(HOST_ARCH_MIPS)
 
 #endif  // defined TARGET_ARCH_MIPS