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Re: [Qemu-devel] [6967] Temporary workaround for ppc on ppc
From: |
Blue Swirl |
Subject: |
Re: [Qemu-devel] [6967] Temporary workaround for ppc on ppc |
Date: |
Thu, 2 Apr 2009 21:18:11 +0300 |
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.
> > 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.