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Re: [PATCH PING 1/5] Named address spaces: core middle-end support
On Fri, Sep 18, 2009 at 3:14 PM, Ulrich Weigand <uweigand@de.ibm.com> wrote:
> I wrote:
>> Richard Guenther wrote:
>> > In tree_type you place the addr_space_t after the flags section.
>> > As it is ?of type char please add a comment that there are
>> > 24 bits left on 32bit archs and 56 bits on 64bit archs (ugh).
>> > Conveniently you may notice that tree_base has 32 spare bits
>> > left (no, I'm not really suggesting to use them here ... well,
>> > maybe - with a big disclaimer). ?Ok, do it - make it a bitfield and
>> > move it to tree_base with a disclaimer that it is only used for
>> > types.
>>
>> Huh, I guess I can do that, but it does seem a bit odd :-)
>>
>> If this is purely a matter of data structure size, maybe a better
>> way might be to reduce the size of the "align" member in tree_type?
>>
>> Anyway, I'll try your suggestion in a follow-on patch.
>
> Like so. ?Was this what you'd been thinking of?
Yes.
Thanks,
Richard.
> Bye,
> Ulrich
>
>
> ChangeLog:
>
> ? ? ? ?* tree.h (struct tree_type): Remove address_space field.
> ? ? ? ?(struct tree_base): Add address_space bitfield. ?Reduce size of "spare".
> ? ? ? ?(TYPE_ADDR_SPACE): Update.
>
> diff -x .pc -x patches -x .svn -urNp gcc-head/gcc/tree.h named-addr-spaces-branch/gcc/tree.h
> --- gcc-head/gcc/tree.h 2009-09-17 15:07:23.000000000 +0200
> +++ named-addr-spaces-branch/gcc/tree.h 2009-09-18 14:55:07.000000000 +0200
> @@ -392,7 +392,12 @@ struct GTY(()) tree_base {
> ? unsigned packed_flag : 1;
> ? unsigned user_align : 1;
>
> - ?unsigned spare : 21;
> + ?unsigned spare : 13;
> +
> + ?/* This field is only used with type nodes; the only reason it is present
> + ? ? in tree_base instead of tree_type is to save space. ?The size of the
> + ? ? field must be large enough to hold addr_space_t values. ?*/
> + ?unsigned address_space : 8;
> ? union tree_ann_d *ann;
> ?};
> @@ -2165,7 +2170,7 @@ extern enum machine_mode vector_type_mod
> ?#define TYPE_RESTRICT(NODE) (TYPE_CHECK (NODE)->type.restrict_flag)
>
> ?/* The address space the type is in. ?*/
> -#define TYPE_ADDR_SPACE(NODE) (TYPE_CHECK (NODE)->type.address_space)
> +#define TYPE_ADDR_SPACE(NODE) (TYPE_CHECK (NODE)->base.address_space)
>
> ?/* There is a TYPE_QUAL value for each type qualifier. ?They can be
> ? ?combined by bitwise-or to form the complete set of qualifiers for a
> @@ -2293,7 +2298,6 @@ struct GTY(()) tree_type {
> ? unsigned lang_flag_5 : 1;
> ? unsigned lang_flag_6 : 1;
>
> - ?addr_space_t address_space;
> ? unsigned int align;
> ? alias_set_type alias_set;
> ? tree pointer_to;
>
>
> --
> ?Dr. Ulrich Weigand
> ?GNU Toolchain for Linux on System z and Cell BE
> ?Ulrich.Weigand@de.ibm.com
>