Re: [PATCH 5/7] Remove one argument abbrev_len in read_partial_die

Simon Marchi
2018-01-29T01:30:50Z

On 2018-01-25 04:38 AM, Yao Qi wrote:
> gdb:
>
> 2018-01-11 Yao Qi <yao.qi@linaro.org>
>
> * dwarf2read.c (read_partial_die): Update the declaration.
> (load_partial_dies): Caller update.
> (read_partial_die): Remove one argument abbrev_len.
> ---
> gdb/dwarf2read.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
> index 9b4d09e..0ee102a 100644
> --- a/gdb/dwarf2read.c
> +++ b/gdb/dwarf2read.c
> @@ -1834,7 +1834,6 @@ static struct partial_die_info *load_partial_dies
> static const gdb_byte *read_partial_die (const struct die_reader_specs *,
> struct partial_die_info *,
> struct abbrev_info *,
> - unsigned int,
> const gdb_byte *);
>
> static struct partial_die_info *find_partial_die (sect_offset, int,
> @@ -18315,8 +18314,8 @@ load_partial_dies (const struct die_reader_specs *reader,
> struct partial_die_info pdi ((sect_offset) (info_ptr - reader->buffer),
> abbrev);
>
> - info_ptr = read_partial_die (reader, &pdi, abbrev, bytes_read,
> - info_ptr);
> + info_ptr = read_partial_die (reader, &pdi, abbrev,
> + (const gdb_byte *) info_ptr + bytes_read);
>
> /* This two-pass algorithm for processing partial symbols has a
> high cost in cache pressure. Thus, handle some simple cases
> @@ -18498,8 +18497,7 @@ partial_die_info::partial_die_info (sect_offset sect_off_,
> static const gdb_byte *
> read_partial_die (const struct die_reader_specs *reader,
> struct partial_die_info *part_die,
> - struct abbrev_info *abbrev, unsigned int abbrev_len,
> - const gdb_byte *info_ptr)
> + struct abbrev_info *abbrev, const gdb_byte *info_ptr)
> {
> struct dwarf2_cu *cu = reader->cu;
> struct dwarf2_per_objfile *dwarf2_per_objfile
> @@ -18512,8 +18510,6 @@ read_partial_die (const struct die_reader_specs *reader,
> int has_high_pc_attr = 0;
> int high_pc_relative = 0;
>
> - info_ptr += abbrev_len;
> -
> for (i = 0; i < abbrev->num_attrs; ++i)
> {
> info_ptr = read_attribute (reader, &attr, &abbrev->attrs[i], info_ptr);
>

I didn't see the value of this change at first, but it makes the meaning of info_ptr
the same in read_partial_die as in skip_one_die, so I think it's good. Could you
improve the documentation of read_partial_die to clarify that INFO_PTR points
after the abbrev code? The skip_one_die doc already specifies that, so you could
just steal it from there.

Simon