MIPS: Fix unaligned address of double.

src/deoptimizer.h

 // 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 19 matching lines @@
 
 #include "v8.h"
 
 #include "allocation.h"
 #include "macro-assembler.h"
 #include "zone-inl.h"
 
 
 namespace v8 {
 namespace internal {
 

[Jakob Kummerow, 2013/05/10 10:06:28]

nit: two empty newlines between top-level things, please.

[palfia, 2013/05/17 17:24:32]

Done.

+// Prevent gcc from using load-double (mips ldc1) on (possibly)
+// non-64-bit aligned address.
+static inline double read_double_value(Address p) {
+#ifndef V8_TARGET_ARCH_MIPS

[danno, 2013/05/10 10:15:55]

I think it's better to use the platform independent V8_HOST_CAN_READ_UNALIGNED
rather than make this MIPS-specific

[palfia, 2013/05/17 17:24:32]

Done.

+  return Memory::double_at(p)
+#else  // V8_TARGET_ARCH_MIPS
+  union conversion {
+    double d;
+    uint32_t u[2];
+  } c;

[danno, 2013/05/10 10:15:55]

And if you do that, you will need to make sure that endianess works correctly,
something like:
uint64_t data = *reinterpret_cast<uint64_t*>(p);
return BitCast<double>(data);

+  c.u[0] = (*reinterpret_cast<uint32_t*>(p));

[Jakob Kummerow, 2013/05/10 10:06:28]

nit: don't need the outer parentheses.

[palfia, 2013/05/17 17:24:32]

Done.

+  c.u[1] = (*reinterpret_cast<uint32_t*>(p + 4));
+  return c.d;
+#endif  // V8_TARGET_ARCH_MIPS
+}
+
 class FrameDescription;
 class TranslationIterator;
 class DeoptimizingCodeListNode;
 class DeoptimizedFrameInfo;
 
 class HeapNumberMaterializationDescriptor BASE_EMBEDDED {
  public:
   HeapNumberMaterializationDescriptor(Address slot_address, double val)
       : slot_address_(slot_address), val_(val) { }
 
@@ skipping 434 matching lines @@
   JSFunction* GetFunction() const { return function_; }
 
   unsigned GetOffsetFromSlotIndex(int slot_index);
 
   intptr_t GetFrameSlot(unsigned offset) {
     return *GetFrameSlotPointer(offset);
   }
 
   double GetDoubleFrameSlot(unsigned offset) {
     intptr_t* ptr = GetFrameSlotPointer(offset);
-#if V8_TARGET_ARCH_MIPS
-    // Prevent gcc from using load-double (mips ldc1) on (possibly)
-    // non-64-bit aligned double. Uses two lwc1 instructions.
-    union conversion {
-      double d;
-      uint32_t u[2];
-    } c;
-    c.u[0] = *reinterpret_cast<uint32_t*>(ptr);
-    c.u[1] = *(reinterpret_cast<uint32_t*>(ptr) + 1);
-    return c.d;
-#else
-    return *reinterpret_cast<double*>(ptr);
-#endif
+    return read_double_value(reinterpret_cast<Address>(ptr));
   }
 
   void SetFrameSlot(unsigned offset, intptr_t value) {
     *GetFrameSlotPointer(offset) = value;
   }
 
   intptr_t GetRegister(unsigned n) const {
     ASSERT(n < ARRAY_SIZE(registers_));
     return registers_[n];
   }
@@ skipping 275 matching lines @@
       case UINT32: {
         uint32_t value = Memory::uint32_at(addr_);
         if (value <= static_cast<uint32_t>(Smi::kMaxValue)) {
           return Handle<Object>(Smi::FromInt(static_cast<int>(value)), isolate);
         } else {
           return isolate->factory()->NewNumber(static_cast<double>(value));
         }
       }
 
       case DOUBLE: {
-        double value = Memory::double_at(addr_);
+        double value = read_double_value(addr_);
         return isolate->factory()->NewNumber(value);
       }
 
       case LITERAL:
         return literal_;
 
       default:
         UNREACHABLE();
         return Handle<Object>::null();
     }
@@ skipping 103 matching lines @@
   Object** expression_stack_;
   int source_position_;
 
   friend class Deoptimizer;
 };
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_DEOPTIMIZER_H_