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Re: [PATCH 1/8] gdb: recognize new DWARF attributes: defaulted, deleted, calling conv.
* Tankut Baris Aktemur <tankut.baris.aktemur@intel.com> [2019-04-23 16:31:47 +0200]:
> Extend GDB's internal representation of types to include the
> DW_AT_calling_convention, DW_AT_defaulted, and DW_AT_deleted attributes
> that were introduced in DWARF5.
>
> gdb/ChangeLog:
>
> * dwarf2read.c (dwarf2_add_member_fn): Read the DW_AT_defaulted
> and DW_AT_deleted attributes of a function.
> (read_structure_type): Read the DW_AT_calling_convention attribute
> of a type.
> * gdbtypes.h (struct fn_field)<defaulted>: New field to store the
> DW_AT_defaulted attribute.
> (struct fn_field)<is_deleted>: New field to store the DW_AT_deleted
> attribute.
> (struct cplus_struct_type)<calling_convention>: New field to store
> the DW_AT_calling_convention attribute.
> (TYPE_FN_FIELD_DEFAULTED): New macro.
> (TYPE_FN_FIELD_DELETED): New macro.
> (TYPE_CPLUS_CALLING_CONVENTION): New macro.
> * gdbtypes.c: (dump_fn_fieldlists): Update for the changes made
> to the .h file.
> (print_cplus_stuff): Likewise.
This looks good to me, with a couple of requests for extended
comments, see below...
>
> ---
> gdb/dwarf2read.c | 20 ++++++++++++++++++++
> gdb/gdbtypes.c | 7 +++++++
> gdb/gdbtypes.h | 19 ++++++++++++++++++-
> 3 files changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
> index 829b07f01ac..435f234f2c9 100644
> --- a/gdb/dwarf2read.c
> +++ b/gdb/dwarf2read.c
> @@ -15539,6 +15539,16 @@ dwarf2_add_member_fn (struct field_info *fip, struct die_info *die,
> if (attr && DW_UNSND (attr) != 0)
> fnp->is_artificial = 1;
>
> + /* Check for defaulted methods. */
> + attr = dwarf2_attr (die, DW_AT_defaulted, cu);
> + if (attr)
> + fnp->defaulted = DW_UNSND (attr);
> +
> + /* Check for deleted methods. */
> + attr = dwarf2_attr (die, DW_AT_deleted, cu);
> + if (attr && DW_UNSND (attr) != 0)
> + fnp->is_deleted = 1;
> +
> fnp->is_constructor = dwarf2_is_constructor (die, cu);
>
> /* Get index in virtual function table if it is a virtual member
> @@ -15859,6 +15869,16 @@ read_structure_type (struct die_info *die, struct dwarf2_cu *cu)
> if (cu->language == language_cplus && die->tag == DW_TAG_class_type)
> TYPE_DECLARED_CLASS (type) = 1;
>
> + /* Store the calling convention in the type if it's available in
> + the die. Otherwise the calling convention remains set to
> + the default value DW_CC_normal. */
> + attr = dwarf2_attr (die, DW_AT_calling_convention, cu);
> + if (attr)
> + {
> + ALLOCATE_CPLUS_STRUCT_TYPE (type);
> + TYPE_CPLUS_CALLING_CONVENTION (type) = DW_UNSND (attr);
> + }
> +
> attr = dwarf2_attr (die, DW_AT_byte_size, cu);
> if (attr)
> {
> diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
> index b3424d81be4..b32f13189a9 100644
> --- a/gdb/gdbtypes.c
> +++ b/gdb/gdbtypes.c
> @@ -4389,6 +4389,10 @@ dump_fn_fieldlists (struct type *type, int spaces)
> TYPE_FN_FIELD_PROTECTED (f, overload_idx));
> printfi_filtered (spaces + 8, "is_stub %d\n",
> TYPE_FN_FIELD_STUB (f, overload_idx));
> + printfi_filtered (spaces + 8, "defaulted %d\n",
> + TYPE_FN_FIELD_DEFAULTED (f, overload_idx));
> + printfi_filtered (spaces + 8, "is_deleted %d\n",
> + TYPE_FN_FIELD_DELETED (f, overload_idx));
> printfi_filtered (spaces + 8, "voffset %u\n",
> TYPE_FN_FIELD_VOFFSET (f, overload_idx));
> }
> @@ -4452,6 +4456,9 @@ print_cplus_stuff (struct type *type, int spaces)
> {
> dump_fn_fieldlists (type, spaces);
> }
> +
> + printfi_filtered (spaces, "calling_convention %d\n",
> + TYPE_CPLUS_CALLING_CONVENTION (type));
> }
>
> /* Print the contents of the TYPE's type_specific union, assuming that
> diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h
> index 147a2de355e..3c7846a0e18 100644
> --- a/gdb/gdbtypes.h
> +++ b/gdb/gdbtypes.h
> @@ -915,6 +915,10 @@ struct fn_field
>
> struct type *fcontext;
>
> + /* * DW_AT_defaulted attribute. */
Taking inspiration from how 'calling_convention' is commented in the
'struct func_type', it would be nice if this comment mentioned what
values can be expected here, something like:
/* * The DW_AT_defaulted attribute for this function, the value is one
of the DW_DEFAULTED enum dwarf_defaulted_attribute constants. */
> +
> + unsigned int defaulted;
> +
> /* Attributes. */
>
> unsigned int is_const:1;
> @@ -932,9 +936,13 @@ struct fn_field
>
> unsigned int is_constructor : 1;
>
> + /* * True if this function is deleted, false otherwise. */
> +
> + unsigned int is_deleted : 1;
> +
> /* * Unused. */
>
> - unsigned int dummy:9;
> + unsigned int dummy:8;
>
> /* * Index into that baseclass's virtual function table, minus 2;
> else if static: VOFFSET_STATIC; else: 0. */
> @@ -1076,6 +1084,11 @@ struct cplus_struct_type
> classes. */
>
> struct symbol **template_arguments;
> +
> + /* * The calling convention for this type, fetched from the
> + DW_AT_calling_convention attribute. */
Similarly it would be nice to include a comment about which values are
valid here, something like:
/* * The calling convention for this type, fetched from the
DW_AT_calling_convention attribute. The value is one of the
DW_CC enum dwarf_calling_convention constants.*/
thanks,
Andrew
> +
> + unsigned calling_convention : 8;
> };
>
> /* * Struct used to store conversion rankings. */
> @@ -1405,6 +1418,8 @@ extern void set_type_vptr_basetype (struct type *, struct type *);
> ? (struct cplus_struct_type*)&cplus_struct_default \
> : TYPE_RAW_CPLUS_SPECIFIC(thistype))
> #define TYPE_RAW_CPLUS_SPECIFIC(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.cplus_stuff
> +#define TYPE_CPLUS_CALLING_CONVENTION(thistype) \
> + TYPE_MAIN_TYPE(thistype)->type_specific.cplus_stuff->calling_convention
> #define TYPE_FLOATFORMAT(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.floatformat
> #define TYPE_GNAT_SPECIFIC(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.gnat_stuff
> #define TYPE_DESCRIPTIVE_TYPE(thistype) TYPE_GNAT_SPECIFIC(thistype)->descriptive_type
> @@ -1521,6 +1536,8 @@ extern void set_type_vptr_basetype (struct type *, struct type *);
> #define TYPE_FN_FIELD_VOFFSET(thisfn, n) ((thisfn)[n].voffset-2)
> #define TYPE_FN_FIELD_VIRTUAL_P(thisfn, n) ((thisfn)[n].voffset > 1)
> #define TYPE_FN_FIELD_STATIC_P(thisfn, n) ((thisfn)[n].voffset == VOFFSET_STATIC)
> +#define TYPE_FN_FIELD_DEFAULTED(thisfn, n) ((thisfn)[n].defaulted)
> +#define TYPE_FN_FIELD_DELETED(thisfn, n) ((thisfn)[n].is_deleted)
>
> /* Accessors for typedefs defined by a class. */
> #define TYPE_TYPEDEF_FIELD_ARRAY(thistype) \
> --
> 2.21.0
>