Fixes Unimplemented crasher on MIPS.

runtime/vm/signal_handler_linux.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"
 #include "vm/simulator.h"
 #include "vm/signal_handler.h"
 #if defined(TARGET_OS_LINUX)
 
 namespace dart {
 
 uintptr_t SignalHandler::GetProgramCounter(const mcontext_t& mcontext) {
   uintptr_t pc = 0;
 
 #if defined(TARGET_ARCH_IA32)
   pc = static_cast<uintptr_t>(mcontext.gregs[REG_EIP]);
 #elif defined(TARGET_ARCH_X64)
   pc = static_cast<uintptr_t>(mcontext.gregs[REG_RIP]);
 #elif defined(TARGET_ARCH_MIPS) && defined(USING_SIMULATOR)
   pc = static_cast<uintptr_t>(mcontext.gregs[REG_EIP]);
 #elif defined(TARGET_ARCH_ARM) && defined(USING_SIMULATOR)
   pc = static_cast<uintptr_t>(mcontext.gregs[REG_EIP]);
 #elif defined(TARGET_ARCH_ARM)
   pc = static_cast<uintptr_t>(mcontext.arm_pc);
+#elif defined(TARGET_ARCH_MIPS)
+  pc = static_cast<uintptr_t>(mcontext.pc);
 #else
   UNIMPLEMENTED();
 #endif  // TARGET_ARCH_...
   return pc;
 }
 
 
 uintptr_t SignalHandler::GetFramePointer(const mcontext_t& mcontext) {
   uintptr_t fp = 0;
 
 #if defined(TARGET_ARCH_IA32)
   fp = static_cast<uintptr_t>(mcontext.gregs[REG_EBP]);
 #elif defined(TARGET_ARCH_X64)
   fp = static_cast<uintptr_t>(mcontext.gregs[REG_RBP]);
 #elif defined(TARGET_ARCH_MIPS) && defined(USING_SIMULATOR)
   fp = static_cast<uintptr_t>(mcontext.gregs[REG_EBP]);
 #elif defined(TARGET_ARCH_ARM) && defined(USING_SIMULATOR)
   fp = static_cast<uintptr_t>(mcontext.gregs[REG_EBP]);
 #elif defined(TARGET_ARCH_ARM)
   fp = static_cast<uintptr_t>(mcontext.arm_fp);
+#elif defined(TARGET_ARCH_MIPS)
+  fp = static_cast<uintptr_t>(mcontext.gregs[30]);
 #else
   UNIMPLEMENTED();
 #endif  // TARGET_ARCH_...
 
   return fp;
 }
 
 
 uintptr_t SignalHandler::GetStackPointer(const mcontext_t& mcontext) {
   uintptr_t sp = 0;
 
 #if defined(TARGET_ARCH_IA32)
   sp = static_cast<uintptr_t>(mcontext.gregs[REG_ESP]);
 #elif defined(TARGET_ARCH_X64)
   sp = static_cast<uintptr_t>(mcontext.gregs[REG_RSP]);
 #elif defined(TARGET_ARCH_MIPS) && defined(USING_SIMULATOR)
   sp = static_cast<uintptr_t>(mcontext.gregs[REG_ESP]);
 #elif defined(TARGET_ARCH_ARM) && defined(USING_SIMULATOR)
   sp = static_cast<uintptr_t>(mcontext.gregs[REG_ESP]);
 #elif defined(TARGET_ARCH_ARM)
   sp = static_cast<uintptr_t>(mcontext.arm_sp);
+#elif defined(TARGET_ARCH_MIPS)
+  sp = static_cast<uintptr_t>(mcontext.gregs[29]);
 #else
   UNIMPLEMENTED();
 #endif  // TARGET_ARCH_...
   return sp;
 }
 
 
 void SignalHandler::Install(SignalAction action) {
   struct sigaction act;
   act.sa_handler = NULL;
   act.sa_sigaction = action;
   sigemptyset(&act.sa_mask);
   act.sa_flags = SA_RESTART | SA_SIGINFO;
   // TODO(johnmccutchan): Do we care about restoring the signal handler?
   struct sigaction old_act;
   int r = sigaction(SIGPROF, &act, &old_act);
   ASSERT(r == 0);
 }
 
 
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_LINUX)