[RFA/DWARF] Add array DW_AT_bit_stride and DW_AT_byte_stride support

[Mark Wielaard]

On Wed, 2014-01-29 at 18:30 +0400, Joel Brobecker wrote:
> gdb/ChangeLog:
> 
>         * gdbtypes.h (create_array_type_with_stride): Add declaration.
>         * gdbtypes.c (create_array_type_with_stride): New function,
>         renaming create_array_type, but with an added parameter
>         called "bit_stride".
>         (create_array_type): Re-implement using
>         create_array_type_with_stride.
>         * dwarf2read.c (read_array_type): Add support for DW_AT_byte_stride
>         and DW_AT_bit_stride attributes.
> 
> gdb/testsuite/ChangeLog:
> 
>         * gdb.dwarf2/arr-stride.c: New file.
>         * gdb.dwarf2/arr-stride.exp: New file.

I know little of the GDB code base, just looking at it because it using
some interesting DWARF, but this patch does look fine to me. Just a few
small nitpicks below.

> +++ b/gdb/gdbtypes.c
> @@ -951,14 +951,18 @@ get_array_bounds (struct type *type, LONGEST *low_bound, LONGEST *high_bound)
>     Elements will be of type ELEMENT_TYPE, the indices will be of type
>     RANGE_TYPE.
>  
> +   If BIT_STRIDE is non-null, build a packed array type whose element
> +   size is BIT_STRIDE.  Otherwise, ignore this parameter.

s/non-null/not zero/ ?

> +/* Same as create_array_type_with_stride but with no bit_stride
> +   (BIT_STRIDE = -1), thus building an unpacked array.  */

Shouldn't that be BIT_STRIDE = 0?

> diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h
> +extern struct type *create_array_type_with_stride
> +  (struct type *, struct type *, struct type *, unsigned int);
> +
>  extern struct type *create_array_type (struct type *, struct type *,
>  				       struct type *);

Personally I would have just added the new argument and fixed up all
callers, just so I had an overview of all the callers that might have a
bit_stride concept that could be added.

Cheers,

Mark