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

[malc]

On Thu, 2 Apr 2009, Blue Swirl wrote:

> On 4/2/09, malc <address@hidden> wrote:
> > On Thu, 2 Apr 2009, Blue Swirl wrote:
> >
> >  > On 4/2/09, malc <address@hidden> 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.

That should work yeah.
 
> >  > 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.
> 
> 

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