On Wed, Jan 16, 2019 at 4:17 PM Tom de Vries <[email protected]> wrote:
>
> this handles DW_FORM_GNU_ref_alt which references the .debug_info
> section in the .gnu_debugaltlink file.
>
> OK for trunk?
>
> Thanks,
> - Tom
>
> On 11-12-18 11:14, Tom de Vries wrote:
> > 2018-12-10 Tom de Vries <[email protected]>
> >
> > * dwarf.c (enum attr_val_encoding): Add ATTR_VAL_REF_ALT_INFO.
> > (struct unit): Add low and high fields.
> > (struct unit_vector): New type.
> > (struct dwarf_data): Add units and units_counts fields.
> > (read_attribute): Handle DW_FORM_GNU_ref_alt using
> > ATTR_VAL_REF_ALT_INFO.
> > (find_unit): New function.
> > (find_address_ranges): Add and handle unit_tag parameter.
> > (build_address_map): Add and handle units_vec parameter.
> > (read_referenced_name_1): Handle DW_FORM_GNU_ref_alt.
> > (build_dwarf_data): Pass units_vec to build_address_map. Store
> > resulting
> > units vector.
> > @@ -281,6 +283,10 @@ struct unit
> > /* The offset of UNIT_DATA from the start of the information for
> > this compilation unit. */
> > size_t unit_data_offset;
> > + /* Start of the compilation unit. */
> > + size_t low;
> > + /* End of the compilation unit. */
> > + size_t high;
The comments should say what low and high are measured in, which I
guess is file offset. Or is it offset from the start of UNIT_DATA?
Either way, If that is right, then the fields should be named
low_offset and high_offset. Otherwise it seems easy to confuse with
function_addrs, where low and high refer to PC values.
Also if they are offsets from UNIT_DATA then size_t is OK, but if the
are file offsets they should be off_t.
> > @@ -2144,6 +2198,22 @@ read_referenced_name_1 (struct dwarf_data *ddata,
> > struct unit *u,
> > || val->encoding == ATTR_VAL_REF_UNIT)
> > return read_referenced_name (ddata, u, val->u.uint, error_callback,
> > data);
> >
> > + if (val->encoding == ATTR_VAL_REF_ALT_INFO)
> > + {
> > + struct unit *alt_unit
> > + = find_unit (ddata->altlink->units, ddata->altlink->units_count,
> > + val->u.uint);
> > + if (alt_unit == NULL)
> > + {
> > + error_callback (data,
> > + "Could not find unit for DW_FORM_GNU_ref_alt", 0);
s/Could/could/
or maybe just skip this error_callback call as discussed earlier.
> > + return NULL;
> > + }
> > + uint64_t unit_offset = val->u.uint - alt_unit->low;
Earlier a unit_offset was the offset of the unit within unit_data, but
here this is an offset within a single unit. This should just be
called offset, which is the name used by read_referenced_name.
This is OK with those changes.
Thanks.
Ian
