On 2023-08-10 12:39, Jakub Jelinek wrote:
On Thu, Aug 10, 2023 at 12:30:06PM -0400, Siddhesh Poyarekar wrote:
The definition of __bos/__bdos allows us the freedom to *estimate* rather
than be precise, so I'd go for sizeof(x) + N * sizeof(*x.a) since it's bound
to give the more conservative answer of the two.
To be precise, we have the 0/1 modes vs. 2/3. So, when not determining
__bos/__bdos from actual allocation size or size of an stack object or
size of data section object but something else (say counted_by), perhaps
0/1 modes should give the upper estimate of sizeof (x) + N * sizeof(elt)
and 2/3 modes should give a lower estimate, so offsetof + N * sizeof(elt),
then user code can continue testing if both modes are equal to have
exact number.
Ack, that's fair.
Thanks,
Sid
