[Mesa-dev] [PATCH] i965/cs: Use dispatch width of 8 for cs terminate

[Jordan Justen]

On 2015-07-16 14:37:59, Jason Ekstrand wrote:
>    On Jul 16, 2015 4:35 PM, "Jordan Justen" <jordan.l.justen at intel.com>
>    wrote:
>    >
>    > On 2015-07-16 13:59:45, Jason Ekstrand wrote:
>    > >    On Jul 16, 2015 2:00 PM, "Jordan Justen"
>    <jordan.l.justen at intel.com>
>    > >    wrote:
>    > >    >
>    > >    > This prevents an assertion failure in brw_fs_live_variables.cpp,
>    > >    > fs_live_variables::setup_one_write: Assertion `var < num_vars'
>    failed.
>    > >
>    > >    Best guess is that you should just fix regs_read to return the
>    right value
>    > >    (1 in this case).  Most other send instructions use mlen but that
>    may not
>    > >    be needed tour CS_TERMINATE.
>    >
>    > I think regs_read will fix a similar assert in setup_one_read. The MOV
>    > will still hit the setup_one_write assert. Should I be generating the
>    > MOV differently?
>    >
>    > For example
>    >
>    >    bld.group(8, 0).exec_all().MOV(payload, g0);
> 
>    Yes, that's how we need to do the MOV.
> 
>    Out of curiosity, why are you emitting a MOV at all and not just calling
>    CS_TERMINATE with g0 directly?

While sending from g0 appears to work, apparently we are supposed to
do the final send from a high register. Ken found some wording that
appeared to indicate that we needed to do this even on compute:

http://article.gmane.org/gmane.comp.video.mesa3d.devel/98098

-Jordan

>    > works in combo with an update to regs_read.
>    >
>    > -Jordan
>    >
>    > >    > Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
>    > >    > Cc: Jason Ekstrand <jason at jlekstrand.net>
>    > >    > ---
>    > >    >  src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 7 ++++---
>    > >    >  1 file changed, 4 insertions(+), 3 deletions(-)
>    > >    >
>    > >    > diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>    > >    b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>    > >    > index 94d6a58..62dfb9a 100644
>    > >    > --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>    > >    > +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>    > >    > @@ -1960,11 +1960,12 @@ fs_visitor::emit_cs_terminate()
>    > >    >      */
>    > >    >     struct brw_reg g0 = retype(brw_vec8_grf(0, 0),
>    > >    BRW_REGISTER_TYPE_UD);
>    > >    >     fs_reg payload = fs_reg(GRF, alloc.allocate(1),
>    > >    BRW_REGISTER_TYPE_UD);
>    > >    > -   bld.exec_all().MOV(payload, g0);
>    > >    > +   const fs_builder bld8 = bld.group(8, 0);
>    > >    > +   bld8.exec_all().MOV(payload, g0);
>    > >    >
>    > >    >     /* Send a message to the thread spawner to terminate the
>    thread. */
>    > >    > -   fs_inst *inst = bld.exec_all()
>    > >    > -                      .emit(CS_OPCODE_CS_TERMINATE, reg_undef,
>    > >    payload);
>    > >    > +   fs_inst *inst = bld8.exec_all()
>    > >    > +                       .emit(CS_OPCODE_CS_TERMINATE, reg_undef,
>    > >    payload);
>    > >    >     inst->eot = true;
>    > >    >  }
>    > >    >
>    > >    > --
>    > >    > 2.1.4
>    > >    >