On 9/12/21 6:40 PM, Dimitry Sibiryakov wrote:
Alex Peshkoff via Firebird-devel wrote 15.05.2018 12:13:
On 05/15/18 13:06, Dimitry Sibiryakov wrote:
15.05.2018 11:58, Alex Peshkoff via Firebird-devel wrote:
Do alignment of fields in C struct matches alignment of the same
fields in MessageBuffer?
If at compile/preprocess time construct a struct to be used
directly in OO API, will it be reliable?
Not always. For example, on 32-bit linux int64 values are aligned
at 4, not 8, bytes.
Perhaps, I could handle it by adding of
__attribute__((aligned(8))) to the declaration of ISC_INT64...
Yes, it does the trick.
I see that alignment of dtype_int128 is set to
sizeof(Firebird::Decimal64) which is 8 bytes, but alignment
requirement of native __int128 is 16 bytes and cannot be decreased
using alignas().
Shouldn't it to be fixed?
Yes, that should be fixed. If one builds FB with native __int128 it
fails on unaligned data access. But changing alignment requirement to 16
bytes is not enough - appears some buffers are not aligned at 16-bit
cause FB fails exactly in the same place. I'm going to fix all that when
have time. BTW, DecFloat(34) is also 16-bit object and I'm afraid that
in a case of PPC build (it has HW support of decfloats) this will cause
same problems.
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