ARM: Don't generate memory instructions with writeback where the data and address registers are the…

runtime/vm/simulator_arm.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 <setjmp.h>  // NOLINT
 #include <stdlib.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM)
 
@@ skipping 1978 matching lines @@
             // The PU field is a 2-bit field.
             UNREACHABLE();
             break;
           }
         }
       }
       if (IsIllegalAddress(addr)) {
         HandleIllegalAccess(addr, instr);
       } else {
         if (write_back) {
+          ASSERT(rd != rn);  // Unpredictable.
           set_register(rn, rn_val);
         }
         if (!instr->HasSign()) {
           if (instr->HasL()) {
             uint16_t val = ReadHU(addr, instr);
             set_register(rd, val);
           } else {
             uint16_t val = get_register(rd);
             WriteH(addr, val, instr);
           }
@@ skipping 296 matching lines @@
     }
     default: {
       UNREACHABLE();
       break;
     }
   }
   if (IsIllegalAddress(addr)) {
     HandleIllegalAccess(addr, instr);
   } else {
     if (write_back) {
+      ASSERT(rd != rn);  // Unpredictable.
       set_register(rn, rn_val);
     }
     if (instr->HasB()) {
       if (instr->HasL()) {
         unsigned char val = ReadBU(addr);
         set_register(rd, val);
       } else {
         unsigned char val = get_register(rd);
         WriteB(addr, val);
       }
@@ skipping 92 matching lines @@
     }
     default: {
       UNREACHABLE();
       break;
     }
   }
   if (IsIllegalAddress(addr)) {
     HandleIllegalAccess(addr, instr);
   } else {
     if (write_back) {
+      ASSERT(rd != rn);  // Unpredictable.
       set_register(rn, rn_val);
     }
     if (instr->HasB()) {
       if (instr->HasL()) {
         unsigned char val = ReadBU(addr);
         set_register(rd, val);
       } else {
         unsigned char val = get_register(rd);
         WriteB(addr, val);
       }
@@ skipping 1446 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(USING_SIMULATOR)
 
 #endif  // defined TARGET_ARCH_ARM