Allow unaligned accesses for ARMv7.

src/arm/simulator-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1048 matching lines @@
 // Some ARM platforms raise an interrupt on detecting unaligned access.
 // On others it does a funky rotation thing.  For now we
 // simply disallow unaligned reads.  Note that simulator runs have the runtime
 // system running directly on the host system and only generated code is
 // executed in the simulator.  Since the host is typically IA32 we will not
 // get the correct ARM-like behaviour on unaligned accesses for those ARM
 // targets that don't support unaligned loads and stores.
 
 
 int Simulator::ReadW(int32_t addr, Instruction* instr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
-  return *ptr;
-#else
-  if ((addr & 3) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
     return *ptr;
+  } else if ((addr & 3) == 0) {

[JF, 2012/10/10 10:35:08]

Why not fold this into the previous block?

if (FLAG_... || ((addr & 3) == 0)) {
} else {
  // UNIMPLEMENTED();
}

Same for the other functions below.

[ulan, 2012/10/10 12:13:28]

Done, thanks.

+    intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
+    return *ptr;
+  } else {
+    PrintF("Unaligned read at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
+           addr,
+           reinterpret_cast<intptr_t>(instr));
+    UNIMPLEMENTED();
+    return 0;
   }
-  PrintF("Unaligned read at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
-         addr,
-         reinterpret_cast<intptr_t>(instr));
-  UNIMPLEMENTED();
-  return 0;
-#endif
 }
 
 
 void Simulator::WriteW(int32_t addr, int value, Instruction* instr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
-  *ptr = value;
-  return;
-#else
-  if ((addr & 3) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
     *ptr = value;
-    return;
+  } else if ((addr & 3) == 0) {
+    intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
+    *ptr = value;
+  } else {
+    PrintF("Unaligned write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
+           addr,
+           reinterpret_cast<intptr_t>(instr));
+    UNIMPLEMENTED();
   }
-  PrintF("Unaligned write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
-         addr,
-         reinterpret_cast<intptr_t>(instr));
-  UNIMPLEMENTED();
-#endif
 }
 
 
 uint16_t Simulator::ReadHU(int32_t addr, Instruction* instr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
-  return *ptr;
-#else
-  if ((addr & 1) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
     return *ptr;
+  } else if ((addr & 1) == 0) {
+    uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
+    return *ptr;
+  } else {
+    PrintF("Unaligned unsigned halfword read at 0x%08x, pc=0x%08"
+           V8PRIxPTR "\n",
+           addr,
+           reinterpret_cast<intptr_t>(instr));
+    UNIMPLEMENTED();
+    return 0;
   }
-  PrintF("Unaligned unsigned halfword read at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
-         addr,
-         reinterpret_cast<intptr_t>(instr));
-  UNIMPLEMENTED();
-  return 0;
-#endif
 }
 
 
 int16_t Simulator::ReadH(int32_t addr, Instruction* instr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  int16_t* ptr = reinterpret_cast<int16_t*>(addr);
-  return *ptr;
-#else
-  if ((addr & 1) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     int16_t* ptr = reinterpret_cast<int16_t*>(addr);
     return *ptr;
+  } else if ((addr & 1) == 0) {
+    int16_t* ptr = reinterpret_cast<int16_t*>(addr);
+    return *ptr;
+  } else {
+    PrintF("Unaligned signed halfword read at 0x%08x\n", addr);
+    UNIMPLEMENTED();
+    return 0;
   }
-  PrintF("Unaligned signed halfword read at 0x%08x\n", addr);
-  UNIMPLEMENTED();
-  return 0;
-#endif
 }
 
 
 void Simulator::WriteH(int32_t addr, uint16_t value, Instruction* instr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
-  *ptr = value;
-  return;
-#else
-  if ((addr & 1) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
     *ptr = value;
-    return;
+  } else if ((addr & 1) == 0) {
+    uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
+    *ptr = value;
+  } else {
+    PrintF("Unaligned unsigned halfword write at 0x%08x, pc=0x%08"
+           V8PRIxPTR "\n",
+           addr,
+           reinterpret_cast<intptr_t>(instr));
+    UNIMPLEMENTED();
   }
-  PrintF("Unaligned unsigned halfword write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
-         addr,
-         reinterpret_cast<intptr_t>(instr));
-  UNIMPLEMENTED();
-#endif
 }
 
 
 void Simulator::WriteH(int32_t addr, int16_t value, Instruction* instr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  int16_t* ptr = reinterpret_cast<int16_t*>(addr);
-  *ptr = value;
-  return;
-#else
-  if ((addr & 1) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     int16_t* ptr = reinterpret_cast<int16_t*>(addr);
     *ptr = value;
-    return;
+  } else if ((addr & 1) == 0) {
+    int16_t* ptr = reinterpret_cast<int16_t*>(addr);
+    *ptr = value;
+  } else {
+    PrintF("Unaligned halfword write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
+           addr,
+           reinterpret_cast<intptr_t>(instr));
+    UNIMPLEMENTED();
   }
-  PrintF("Unaligned halfword write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
-         addr,
-         reinterpret_cast<intptr_t>(instr));
-  UNIMPLEMENTED();
-#endif
 }
 
 
 uint8_t Simulator::ReadBU(int32_t addr) {
   uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
   return *ptr;
 }
 
 
 int8_t Simulator::ReadB(int32_t addr) {
   int8_t* ptr = reinterpret_cast<int8_t*>(addr);
   return *ptr;
 }
 
 
 void Simulator::WriteB(int32_t addr, uint8_t value) {
   uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
   *ptr = value;
 }
 
 
 void Simulator::WriteB(int32_t addr, int8_t value) {
   int8_t* ptr = reinterpret_cast<int8_t*>(addr);
   *ptr = value;
 }
 
 
 int32_t* Simulator::ReadDW(int32_t addr) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  int32_t* ptr = reinterpret_cast<int32_t*>(addr);
-  return ptr;
-#else
-  if ((addr & 3) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     int32_t* ptr = reinterpret_cast<int32_t*>(addr);
     return ptr;
+  } else if ((addr & 3) == 0) {
+    int32_t* ptr = reinterpret_cast<int32_t*>(addr);
+    return ptr;
+  } else {
+    PrintF("Unaligned read at 0x%08x\n", addr);
+    UNIMPLEMENTED();
+    return 0;
   }
-  PrintF("Unaligned read at 0x%08x\n", addr);
-  UNIMPLEMENTED();
-  return 0;
-#endif
 }
 
 
 void Simulator::WriteDW(int32_t addr, int32_t value1, int32_t value2) {
-#if V8_TARGET_CAN_READ_UNALIGNED
-  int32_t* ptr = reinterpret_cast<int32_t*>(addr);
-  *ptr++ = value1;
-  *ptr = value2;
-  return;
-#else
-  if ((addr & 3) == 0) {
+  if (FLAG_enable_unaligned_accesses) {
     int32_t* ptr = reinterpret_cast<int32_t*>(addr);
     *ptr++ = value1;
     *ptr = value2;
-    return;
+  } else if ((addr & 3) == 0) {
+    int32_t* ptr = reinterpret_cast<int32_t*>(addr);
+    *ptr++ = value1;
+    *ptr = value2;
+  } else {
+    PrintF("Unaligned write at 0x%08x\n", addr);
+    UNIMPLEMENTED();
   }
-  PrintF("Unaligned write at 0x%08x\n", addr);
-  UNIMPLEMENTED();
-#endif
 }
 
 
 // Returns the limit of the stack area to enable checking for stack overflows.
 uintptr_t Simulator::StackLimit() const {
   // Leave a safety margin of 1024 bytes to prevent overrunning the stack when
   // pushing values.
   return reinterpret_cast<uintptr_t>(stack_) + 1024;
 }
 
@@ skipping 2172 matching lines @@
   uintptr_t address = *stack_slot;
   set_register(sp, current_sp + sizeof(uintptr_t));
   return address;
 }
 
 } }  // namespace v8::internal
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_ARM