[RFD] Extremely large alignment of read-only strings

Thorsten Glaser tg@mirbsd.de
Thu Jul 28 19:02:00 GMT 2016


Alexander Monakov dixit:

>First of all, I think option -malign-data=abi (new in GCC 5) addresses your
>need: it can be used to reduce the default (excessive) alignment to just the
>psABI-dictated value (you can play with this at https://gcc.godbolt.org even if

Ah, nice!

>Note that like with other ABI-affecting options you need to consider
>implications for linking with code you're not building yourself: if the other
>code expects bigger alignment, you'll have a bug.

Yes, of course, but in this case, “the other code” is libc,
and it “better behave”. ☺

>> I was using, also worked for C, not just C++), which showed
>> me that the alignment was 256 even (only later reduced to
>> 32 as that’s the maximum alignment for i386).
>
>Most likely the quoted figures from GCC dumps are in bits, not bytes.

Oh, or that. That makes more sense, yes, thanks.

bye,
//mirabilos
-- 
“It is inappropriate to require that a time represented as
 seconds since the Epoch precisely represent the number of
 seconds between the referenced time and the Epoch.”
	-- IEEE Std 1003.1b-1993 (POSIX) Section B.2.2.2



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