Fixes a bug in MIPS simulator runtime call handling.

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 271 matching lines @@
   arg1[ARG_SIZE] = 0;
   arg2[ARG_SIZE] = 0;
 
   // Undo all set breakpoints while running in the debugger shell. This will
   // make them invisible to all commands.
   UndoBreakpoints();
 
   while (!done) {
     if (last_pc != sim_->get_pc()) {
       last_pc = sim_->get_pc();
-      Disassembler::Disassemble(last_pc, last_pc + Instr::kInstrSize);
+      if (Simulator::IsIllegalAddress(last_pc)) {
+        OS::Print("pc is out of bounds: 0x%"Px"\n", last_pc);
+      } else {
+        Disassembler::Disassemble(last_pc, last_pc + Instr::kInstrSize);
+      }
     }
     char* line = ReadLine("sim> ");
     if (line == NULL) {
       FATAL("ReadLine failed");
     } else {
       // Use sscanf to parse the individual parts of the command line. At the
       // moment no command expects more than two parameters.
       int args = SScanF(line,
                         "%" XSTR(COMMAND_SIZE) "s "
                         "%" XSTR(ARG_SIZE) "s "
@@ skipping 594 matching lines @@
       set_register(A3, icount_);
       set_register(TMP, icount_);
       set_register(RA, icount_);
 
       // Zap floating point registers.
       double zap_dvalue = static_cast<double>(icount_);
       for (int i = F0; i <= F31; i++) {
         set_fregister(static_cast<FRegister>(i), zap_dvalue);
       }
 
-      // Return.
-      set_pc(saved_ra);
+      // Return. Subtract to account for pc_ increment after return.
+      set_pc(saved_ra - Instr::kInstrSize);
     }
   } else {
     SimulatorDebugger dbg(this);
     dbg.Stop(instr, "breakpoint");
   }
 }
 
 
 void Simulator::DecodeSpecial(Instr* instr) {
   ASSERT(instr->OpcodeField() == SPECIAL);
@@ skipping 58 matching lines @@
 
       set_lo_register(rs_val / rt_val);
       set_hi_register(rs_val % rt_val);
       break;
     }
     case JALR: {
       ASSERT(instr->RtField() == R0);
       ASSERT(instr->RsField() != instr->RdField());
       ASSERT(!delay_slot_);
       // Format(instr, "jalr'hint 'rd, rs");
+      set_register(instr->RdField(), pc_ + 2*Instr::kInstrSize);
       uword next_pc = get_register(instr->RsField());
       ExecuteDelaySlot();
       // Set return address to be the instruction after the delay slot.
-      set_register(instr->RdField(), pc_ + Instr::kInstrSize);
       pc_ = next_pc - Instr::kInstrSize;  // Account for regular PC increment.
       break;
     }
     case JR: {
       ASSERT(instr->RtField() == R0);
       ASSERT(instr->RdField() == R0);
       ASSERT(!delay_slot_);
       // Format(instr, "jr'hint 'rs");
       uword next_pc = get_register(instr->RsField());
       ExecuteDelaySlot();
@@ skipping 621 matching lines @@
   // Restore the SP register and return R1:R0.
   set_register(SP, sp_before_call);
   return Utils::LowHighTo64Bits(get_register(V0), get_register(V1));
 }
 
 }  // namespace dart
 
 #endif  // !defined(HOST_ARCH_MIPS)
 
 #endif  // defined TARGET_ARCH_MIPS