Em Tue, Mar 26, 2019 at 11:30:54AM -0700, andrii.nakryiko@xxxxxxxxx escreveu:
> From: Andrii Nakryiko <andriin@xxxxxx>
>
> Counting field sizes only in bits causes confusion and lots of differing
> output, when compared to previous logic. This commit changes logic so
> that it counts bit size of bitfield fields separately from byte size of
> non-bitfield fields. In the end, if there were bit holes, this bit size
> is emitted explicitly. This makes output for struct/unions not using
> bitfields identical, while also preserving correctness (and data
> completeness) for cases with bitfields and bit holes.
>
> Example (-before/+after):
> struct cfg80211_pmsr_request_peer {
> u8 addr[6]; /* 0 6 */
>
> /* XXX 2 bytes hole, try to pack */
>
> struct cfg80211_chan_def chandef; /* 8 24 */
>
> /* XXX last struct has 4 bytes of padding */
>
> u8 report_ap_tsf:1; /* 32: 0 1 */
>
> /* XXX 7 bits hole, try to pack */
> /* XXX 3 bytes hole, try to pack */
>
> struct cfg80211_pmsr_ftm_request_peer ftm; /* 36 12 */
>
> /* XXX last struct has 1 byte of padding */
>
> /* size: 48, cachelines: 1, members: 4 */
> - /* sum members: 43, holes: 2, sum holes: 5 */
> - /* bit holes: 1, sum bit holes: 7 bits */
> + /* sum members: 42, holes: 2, sum holes: 5 */
> + /* sum bitfield members: 1 bits, bit holes: 1, sum bit holes: 7 bits */
> /* paddings: 2, sum paddings: 5 */
> /* last cacheline: 48 bytes */
> };
Looks more clear, indeed, thanks for the patch, applying and testing!
- Arnaldo
> Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> ---
> dwarves_fprintf.c | 25 +++++++++++++++----------
> 1 file changed, 15 insertions(+), 10 deletions(-)
>
> diff --git a/dwarves_fprintf.c b/dwarves_fprintf.c
> index 4a9b26c..cd6c8b9 100644
> --- a/dwarves_fprintf.c
> +++ b/dwarves_fprintf.c
> @@ -1228,7 +1228,7 @@ static size_t __class__fprintf(struct class *class, const struct cu *cu,
> size_t last_size = 0, size;
> uint8_t newline = 0;
> uint16_t nr_paddings = 0;
> - uint32_t sum = 0;
> + uint32_t sum_bytes = 0, sum_bits = 0;
> uint32_t sum_holes = 0;
> uint32_t sum_paddings = 0;
> uint32_t sum_bit_holes = 0;
> @@ -1444,7 +1444,11 @@ static size_t __class__fprintf(struct class *class, const struct cu *cu,
> continue;
> #endif
>
> - sum += pos->bitfield_size ? pos->bitfield_size : pos->bit_size;
> + if (pos->bitfield_size) {
> + sum_bits += pos->bitfield_size;
> + } else {
> + sum_bytes += pos->byte_size;
> + }
>
> if (last == NULL || /* First member */
> /*
> @@ -1487,15 +1491,15 @@ static size_t __class__fprintf(struct class *class, const struct cu *cu,
> printed += type__fprintf_stats(type, cu, &cconf, fp);
>
> if (sum_holes > 0)
> - printed += fprintf(fp, "%.*s/* sum members (bits): %u, holes: %d, "
> + printed += fprintf(fp, "%.*s/* sum members: %u, holes: %d, "
> "sum holes: %u */\n",
> cconf.indent, tabs,
> - sum, class->nr_holes, sum_holes);
> + sum_bytes, class->nr_holes, sum_holes);
> if (sum_bit_holes > 0)
> - printed += fprintf(fp, "%.*s/* bit holes: %d, sum bit "
> - "holes: %u bits */\n",
> + printed += fprintf(fp, "%.*s/* sum bitfield members: %u bits, bit holes: %d, "
> + "sum bit holes: %u bits */\n",
> cconf.indent, tabs,
> - class->nr_bit_holes, sum_bit_holes);
> + sum_bits, class->nr_bit_holes, sum_bit_holes);
> if (class->padding > 0)
> printed += fprintf(fp, "%.*s/* padding: %u */\n",
> cconf.indent,
> @@ -1524,13 +1528,14 @@ static size_t __class__fprintf(struct class *class, const struct cu *cu,
> m->byte_size);
> }
>
> - size_diff = type->size * 8 - (sum + sum_holes * 8 + sum_bit_holes +
> + size_diff = type->size * 8 - (sum_bytes * 8 + sum_bits + sum_holes * 8 + sum_bit_holes +
> class->padding * 8 + class->bit_padding);
> if (size_diff && type->nr_members != 0)
> - printed += fprintf(fp, "\n%.*s/* BRAIN FART ALERT! %d bytes != %u (member bits) "
> + printed += fprintf(fp, "\n%.*s/* BRAIN FART ALERT! %d bytes != "
> + "%u (member bytes) + %u (member bits) "
> "+ %u (byte holes) + %u (bit holes), diff = %d bits */\n",
> cconf.indent, tabs,
> - type->size, sum, sum_holes, sum_bit_holes, size_diff);
> + type->size, sum_bytes, sum_bits, sum_holes, sum_bit_holes, size_diff);
> out:
> return printed + fprintf(fp, "%.*s}%s%s", indent, tabs,
> cconf.suffix ? " ": "", cconf.suffix ?: "");
> --
> 2.17.1
--
- Arnaldo
