Hi SQLite users; I have a question about _sqliteZone_ in mem1.c. I notice that the address of this static variable is used in a call to OSAtomicCompareAndSwapPtrBarrier on MacOS and iOS. That system call is declared in OSAtomic.h, which includes a note about the pointer alignment of its arguments:
> * WARNING: all addresses passed to these functions must be "naturally > aligned", > * i.e. * <code>int32_t</code> pointers must be 32-bit aligned (low 2 bits of > * address are zeroes), and <code>int64_t</code> pointers must be 64-bit > aligned > * (low 3 bits of address are zeroes.) I wonder, therefore, if it might be prudent to declare _sqliteZone_ with the alignment attribute, so that the compiler is sure to put it at a 32 / 64 bit aligned address space? e .g. static __attribute__((aligned(8))) malloc_zone_t* _sqliteZone_; and also, because this local variable is used in that same function: __attribute__((aligned(8))) malloc_zone_t* newzone = malloc_create_zone(4096, 0); I see that attribute is used one other place, so this may be an important nuance. On a 32-bit architecture, it would be safe to use aligned(4) instead of aligned(8) but I'm not sure anyone will care about the (possible) 4-byte savings. - Andy
