On Wed, 15 Aug 2018, Tom de Vries wrote:
> Hi,
>
> This patch adds option -greadable-dwarf. In absence of an DW_AT_comment
> attribute,
What's a DW_AT_comment attribute? I don't see this mentioned in the
patch.
> it sets the DW_AT_name attribute of dies that otherwise do not get
> that attribute, to make it easier to figure out what the die is describing.
>
> The option exports the names of artificial variables:
> ...
> DIE 0: DW_TAG_variable (0x7fa934dd54b0)
> + DW_AT_name: "D.1922"
> DW_AT_type: die -> 0 (0x7fa934dd0d70)
> DW_AT_artificial: 1
>
> ...
> which can be traced back to gimple dumps:
> ...
> char a[0:D.1922] [value-expr: *a.0];
> ...
>
> Furthermore, it adds names to external references:
> ...
> DIE 0: DW_TAG_subprogram (0x7fa88b9650f0)
> +DW_AT_name: "main"
> DW_AT_abstract_origin: die -> label: vla_1.c.6719312a + 29 (0x7fa88b965140)
> ...
>
> This is an undocumented developer-only option, because using this option may
> change behaviour of dwarf consumers, f.i., gdb shows the artificial variables:
> ...
> (gdb) info locals
> a = 0x7fffffffda90 "\005"
> D.4278 = <optimized out>
> ...
>
> Any comments?
The idea is OK I guess but I'd call it -gforce-named-dies instead
of -greadable-dwarf. It also goes only half-way since it doesn't
add names to DECL_NAMELESS vars.
There doesn't seem to be a convenient place to
> Thanks,
> - Tom
>
> [debug] Add -greadable-dwarf
>
> 2018-08-15 Tom de Vries <tdevr...@suse.de>
>
> * common.opt (greadable-dwarf): Add option.
> * dwarf2out.c (add_name_and_src_coords_attributes): Add param. Add name
> for artifical decls.
> (add_decl_name): New function.
> (dwarf2out_register_external_die): Add name to external reference die.
>
> ---
> gcc/common.opt | 5 +++++
> gcc/dwarf2out.c | 24 +++++++++++++++++++++---
> 2 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/common.opt b/gcc/common.opt
> index b2f2215ecc6..6e5e0558e49 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -2972,6 +2972,11 @@ gstrict-dwarf
> Common Driver Report Var(dwarf_strict) Init(0)
> Don't emit DWARF additions beyond selected version.
>
> +greadable-dwarf
> +Common Driver Undocumented Report Var(flag_readable_dwarf) Init(0)
> +Make generated dwarf more readable, at the cost of space and exposing
> compiler
> +internals.
> +
> gtoggle
> Common Driver Report Var(flag_gtoggle)
> Toggle debug information generation.
> diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
> index 4b63cbd8a1e..8c6b4372874 100644
> --- a/gcc/dwarf2out.c
> +++ b/gcc/dwarf2out.c
> @@ -3824,7 +3824,9 @@ static void add_prototyped_attribute (dw_die_ref, tree);
> static dw_die_ref add_abstract_origin_attribute (dw_die_ref, tree);
> static void add_pure_or_virtual_attribute (dw_die_ref, tree);
> static void add_src_coords_attributes (dw_die_ref, tree);
> -static void add_name_and_src_coords_attributes (dw_die_ref, tree, bool =
> false);
> +static void add_name_and_src_coords_attributes (dw_die_ref, tree, bool =
> false,
> + bool = false);
> +static void add_decl_name (dw_die_ref, tree);
> static void add_discr_value (dw_die_ref, dw_discr_value *);
> static void add_discr_list (dw_die_ref, dw_discr_list_ref);
> static inline dw_discr_list_ref AT_discr_list (dw_attr_node *);
> @@ -6022,6 +6024,8 @@ dwarf2out_register_external_die (tree decl, const char
> *sym,
> else
> equate_decl_number_to_die (decl, die);
>
> + if (flag_readable_dwarf)
> + add_decl_name (die, decl);
Please use add_name_and_src_coords_attributes directly.
> /* Add a reference to the DIE providing early debug at $sym + off. */
> add_AT_external_die_ref (die, DW_AT_abstract_origin, sym, off);
> }
> @@ -21269,7 +21273,8 @@ add_linkage_name (dw_die_ref die, tree decl)
>
> static void
> add_name_and_src_coords_attributes (dw_die_ref die, tree decl,
> - bool no_linkage_name)
> + bool no_linkage_name,
> + bool no_src_coords_attributes)
> {
> tree decl_name;
>
> @@ -21279,12 +21284,19 @@ add_name_and_src_coords_attributes (dw_die_ref die,
> tree decl,
> const char *name = dwarf2_name (decl, 0);
> if (name)
> add_name_attribute (die, name);
> - if (! DECL_ARTIFICIAL (decl))
> + if (!no_src_coords_attributes && ! DECL_ARTIFICIAL (decl))
inconsistent spacing after !
> add_src_coords_attributes (die, decl);
>
> if (!no_linkage_name)
> add_linkage_name (die, decl);
> }
> + else if (flag_readable_dwarf && decl_name == NULL)
> + {
> + char *buf = XNEWVEC (char, 32);
> + char decl_letter = TREE_CODE (decl) == CONST_DECL ? 'C' : 'D';
> + sprintf (buf, "%c.%u", decl_letter, DECL_UID (decl));
> + add_name_attribute (die, buf);
I think you leak 'buf'.
> + }
>
> #ifdef VMS_DEBUGGING_INFO
how does it interact with this VMS_DEBUGGING_INFO path?
> /* Get the function's name, as described by its RTL. This may be different
> @@ -21298,6 +21310,12 @@ add_name_and_src_coords_attributes (dw_die_ref die,
> tree decl,
> #endif /* VMS_DEBUGGING_INFO */
> }
>
> +static void
> +add_decl_name (dw_die_ref die, tree decl)
> +{
> + add_name_and_src_coords_attributes (die, decl, true, true);
> +}
> +
> /* Add VALUE as a DW_AT_discr_value attribute to DIE. */
>
> static void
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
