Re: [PATCH] backend: compare word-at-a-time in bcTruelen

On Tue, Jun 16, 2009 at 8:38 AM, Greg Stark<gsstark@mit.edu> wrote:
> On Tue, Jun 16, 2009 at 1:03 PM, Robert Haas<robertmhaas@gmail.com> wrote:
>> I see that... but I don't think the test in the first loop is correct.
>>  It's based on the value of i % 4, but I'm not convinced that you know
>> anything about the alignment at the point where i == 0.
>
> That's correct. To check the alignment you would have to look at the
> actual pointer. I would suggest using the existing macros to handle
> alignment. Hm, though the only one I see offhand which is relevant is
> the moderately silly PointerIsAligned(). Still it would make the code
> clearer even if it's pretty simple.
>
> Incidentally, the char foo[4] = {' ',' ',' ',' '} suggestion is, I
> think, bogus. There would be no alignment guarantee on that array.
> Personally I'm find with 0x20202020 with a comment explaining what it
> is.

Ooh, good point.  I still don't like the 0x20 thing, but using uint32
instead of int or long is the main point, unless we support any
platforms where 0x20 != ' '.

...Robert