[Pnet-developers] CVMWord union and ReadLong Int32/Int64 mismatch?

[Peter Colson]

I'm trying to figure out the meaning (and terminology) of the following 
code.

In cvm.h the CVMWord union has no mention of Int64's (although, it 
could be assumed that on a 64-bit arch that void* is equivalent to an 
Int64):

typedef union
{
    ILInt32     intValue;
    ILUInt32  uintValue;
    void         *ptrValue;
    /* Pad this structure to the best alignment on the underlying 
platform.
       This is usually needed on 64-bit platforms to ensure that stack
       words are always aligned on the best boundary.  We don't do this 
for
       i386 because IL_BEST_ALIGNMENT is sometimes 8, and we need it to 
be 4 */
#if !defined(__i386) && !defined(__i386__)
    char        padding[IL_BEST_ALIGNMENT];
#endif
} CVMWord;

In cvm.c, the function 'ReadLong' (where long presumably means an 
integral type) is assumed to be an Int64
taken from the same union above that only contains Int32 integrals:

/*
 * Read a long value from a stack position.
 */
static IL_INLINE ILInt64 ReadLong(CVMWord *stack)
{
#ifdef CVM_LONGS_ALIGNED_WORD
    return *((ILInt64 *)stack);
#else
    ILInt64 temp;
    ILMemCpy(&temp, stack, sizeof(ILInt64));
    return temp;
#endif
}

I don't understand the Int32/Int64 mismatch here?


Regards,
Peter Colson,