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Re: [patch] Add support for <struct> and <flags> in target descriptions


On Sun, Feb 28, 2010 at 4:15 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Feb 22, 2010 at 8:45 AM, Daniel Jacobowitz <dan@codesourcery.com> wrote:
>> Hi H.J.,
>>
>> This patch adds <flags> support to the XML language. ?Could you try
>> using this to move the two x86 flags registers from out of
>> target-descriptions.c?
>>
>> The flags support is straightforward and covered by the manual.
>> It's not tested because I couldn't find a way to do so; you can't
>> ptype a flags register, and you can't add dummy registers whose value
>> you can get at, only for ptype.
>>
>> The patch also adds <struct>, which is a little more interesting.
>> It's got two forms:
>>
>> * Register containing integer bitfields. ?Each field must be
>> explicitly positioned. ?The size must be pre-declared - otherwise
>> the representation GDB uses for big-endian bitfields can't figure out
>> how far from the MSB edge of the register the field is.
>>
>> * Register containing typed non-bitfield structures. ?Each field must
>> be implicitly positioned. ?There's no support for padding.
>>
>> These are somewhat annoying limitations, but they suffice for
>> everything I've needed this for since I wrote the patch, which was
>> originally several years ago; it's been stuck in my submission queue
>> because it was tangled up with other local patches. ?Since they are
>> "must" restrictions, they are easy to lift in the future; we can make
>> GDB more permissive.
>>
>> These I was able to type, although I'd have liked more exhaustive
>> tests... for that, I'd need typeof, which turns out to be annoyingly
>> hard to implement in GDB's parser :-(
>>
>> Eli, how's the documentation?
>>
>> --
>> Daniel Jacobowitz
>> CodeSourcery
>>
>> 2010-02-22 ?Daniel Jacobowitz ?<dan@codesourcery.com>
>>
>> ? ? ? ?* gdbtypes.c (append_composite_type_field_raw): New.
>> ? ? ? ?(append_composite_type_field_aligned): Use the new function.
>> ? ? ? ?* gdbtypes.h (append_composite_type_field_raw): Declare.
>> ? ? ? ?* target-descriptions.c (struct tdesc_type_field): Add start and end.
>> ? ? ? ?(struct tdesc_type_flag): New type.
>> ? ? ? ?(struct tdesc_type): Add TDESC_TYPE_STRUCT and TDESC_TYPE_FLAGS to
>> ? ? ? ?kind. ?Add size to u.u. ?Add u.f for flags.
>> ? ? ? ?(tdesc_gdb_type): Handle TDESC_TYPE_STRUCT and TDESC_TYPE_FLAGS.
>> ? ? ? ?(tdesc_free_type): Likewise.
>> ? ? ? ?(tdesc_create_struct, tdesc_set_struct_size, tdesc_create_flags): New.
>> ? ? ? ?(tdesc_add_field): Handle TDESC_TYPE_STRUCT.
>> ? ? ? ?(tdesc_add_bitfield, tdesc_add_flag): New.
>> ? ? ? ?* target-descriptions.h (tdesc_create_struct, tdesc_set_struct_size)
>> ? ? ? ?(tdesc_create_flags, tdesc_add_bitfield, tdesc_add_flag): Declare.
>> ? ? ? ?* xml-tdesc.c (struct tdesc_parsing_data): Rename current_union to
>> ? ? ? ?current_type. ?Add current_type_size and current_type_is_flags.
>> ? ? ? ?(tdesc_start_union): Clear the new fields.
>> ? ? ? ?(tdesc_start_struct, tdesc_start_flags): New.
>> ? ? ? ?(tdesc_start_field): Handle struct fields, including bitfields.
>> ? ? ? ?(field_attributes): Make type optional. ?Add start and end.
>> ? ? ? ?(union_children): Rename to struct_union_children.
>> ? ? ? ?(union_attributes): Rename to struct_union_attributes. ?Add optional
>> ? ? ? ?size.
>> ? ? ? ?(flags_attributes): New.
>> ? ? ? ?(feature_children): Add struct and flags.
>> ? ? ? ?* features/gdb-target.dtd: Add flags and struct to features.
>> ? ? ? ?Make field type optional. ?Add field start and end.
>>
>> ? ? ? ?* gdb.texinfo (Types): Describe <struct> and <flags>.
>>
>> ? ? ? ?* gdb.xml/extra-regs.xml: Add struct1, struct2, and flags
>> ? ? ? ?types. ?Add structreg, bitfields, and flags registers.
>> ? ? ? ?* gdb.xml/tdesc-regs.exp: Test structreg and bitfields
>> ? ? ? ?registers.
>>
>
> It doesn't work. "case TDESC_TYPE_FLAGS:" is missing in
> maint_print_c_tdesc_cmd.
>
>

This patch makes it to work. However, there is no equivalent of

append_flags_type_flag (type, 1, NULL);

I have

  <flags id="i386_eflags" size="4">
    <field name="CF" start="0" end="0"/>
    <field name="" start="1" end="1"/>
    <field name="PF" start="2" end="2"/>
....

I got

(gdb) p $eflags
$1 = [  PF ZF IF ]
           ^ extra white space
(gdb)

instead of
(gdb) p $eflags
$1 = [ PF ZF IF ]
(gdb)




-- 
H.J.

Attachment: gdb-flag-1.patch
Description: Text document


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