Re: [PATCH v4 11/11] pack-objects.h: reorder members to shrink struct object_entry

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 16, 2018, 21:02 UTC
Message-ID: <xmqq370z20p5.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20180316183200.31014-12-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

Show 5 quoted lines

> Previous patches leave lots of holes and padding in this struct. This
> patch reorders the members and shrinks the struct down to 80 bytes
> (from 136 bytes, before any field shrinking is done) with 16 bits to
> spare (and a couple more in in_pack_header_size when we really run out
> of bits).

Nice.

I am wondering if we need some conditional code for 32-bit platform. For example, you have uint32_t field and do things like this:

        static inline int oe_size_less_than(const struct object_entry *e,
                                            unsigned long limit)
        {
                if (e->size_valid)
                        return e->size_ < limit;
                if (limit > maximum_unsigned_value_of_type(uint32_t))
                        return 1;
                return oe_size(e) < limit;
        }

Do we and compilers do the right thing when your ulong is uint32_t?