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DBD::SQLite alignment fix 2 Comments More | Login | Reply /

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  • Given that memcpy is prototyped void *memcpy(void *dst, const void *src, size_t len); is sqlite actually at fault here? Or is the gcc optimisation buggy? I'm not a sufficiently good C standards guru to know this, even if I looked at precisely what the code is doing. (Which I confess, I haven't)

    • I believe both are at fault. GCC should not provide this optimization in *all* cases, at least without providing an option on those platforms to specifically disable it (curiously, there's an option for MIPS but not Solaris).

      On the SQLite side, arrays of char * were being casted to structs and then memcpy'd. With this layout, every other array element was misaligned on Solaris, but it was fine on x86. Very, very bad. D. Richard Hipp (author of SQLite) and I actually worked out a better solution than my patch -- using the fact that malloc() always returns 8-byte aligned addresses on Solaris, he fiddled with the allocation of the structures to guarantee 8-byte alignment. Much cleaner! I believe version 3.0.8 has this fix.

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