Re: [Qemu-devel] [6967] Temporary workaround for ppc on ppc

[Blue Swirl <blauwirbel@gmail.com>]

On 4/2/09, malc <av1474@comtv.ru> wrote:
> On Thu, 2 Apr 2009, Blue Swirl wrote:
>
>  > On 4/2/09, malc <av1474@comtv.ru> wrote:
>  > > Revision: 6967
>  > >           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6967
>  > >  Author:   malc
>  > >  Date:     2009-04-02 01:16:39 +0000 (Thu, 02 Apr 2009)
>  > >  Log Message:
>  > >  -----------
>  > >  Temporary workaround for ppc on ppc
>  > >
>  > >  target-ppc/translate.c puts values of type opcode_t into .opcodes
>  > >  section, using GCC extension to do so, and hoping that this will make
>  > >  them appear contiguously and in the source order in the resulting
>  > >  executable. This assumption is not safe and is known to be violated
>  > >  with certain versions of GCC, certain flags passed to it and on
>  > >  certain platforms (gcc 4.3.0, -O and PPC/PPC64 for instance)
>  >
>  > I've always wondered if the section hack was a very clever one or too
>  > clever one, this makes it clear.
>  >
>  > The section uses could be removed by moving the opcode tables towards
>
>
> There are _no_ opcode tables that's why it fails. The code just does
>
>  opcode_t in_section(.opcodes) start;
>  <lots of opcode_t>;
>  opcode_t in_section(.opcodes) end;
>
>  And then scans from &start to &end.
>
>  The only way, that i know of, to make that work is to indeed put
>  things into a table (an array).

Yes, that's what I meant.

The alternative is to move the opcodes to a new file, which is
included two times by translate.c, first to get the opcode function
definitions and second time to construct the table. This is what I
meant with the #include trick below.

>  > the end of file and making the handler functions use normal C
>  > declarations or aided with a macro. That separates the function and
>  > its table entry a lot, but I guess we don't want to use the #include
>  > trick this time?
>
>
> I think PPC's translate.c should be just split and massaged a lot.

Fully agree.