[Mesa-dev] [PATCH v2 07/20] i965/fs: fix lower SIMD width for IVB/BYT's MOV_INDIRECT

[Samuel Iglesias Gonsálvez]

On Tue, 2017-01-17 at 14:15 -0800, Francisco Jerez wrote:
> Samuel Iglesias Gonsálvez <siglesias at igalia.com> writes:
> 
> > From: "Juan A. Suarez Romero" <jasuarez at igalia.com>
> > 
> > Previous to Broadwell, we have 8 registers for MOV_INDIRECT.
> > 
> > According to the IVB and HSW PRMs:
> > 
> > "2.When the destination requires two registers and the sources are
> >  indirect, the sources must use 1x1 regioning mode. In addition,
> > the
> >  sources must be assembled from GRF registers each accessed by
> > adjacent
> >  index registers in 1x1 regioning modes."
> > 
> > So for DF instructions the execution size is not limited by the
> > number
> > of address registers that are available, but by the EU
> > decompression
> > logic not handling VxH indirect addressing correctly.
> > 
> > This patch limits the SIMD width to 4 in this case.
> > 
> > v2:
> > - Fix typo (Matt).
> > - Fix condition (Curro)
> > 
> > Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
> > Signed-off-by: Juan A. Suarez Romero <jasuarez at igalia.com>
> > ---
> >  src/mesa/drivers/dri/i965/brw_fs.cpp | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
> > b/src/mesa/drivers/dri/i965/brw_fs.cpp
> > index a2ba0fde9fd..c9b6c995dc9 100644
> > --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> > +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> > @@ -4870,11 +4870,16 @@ get_lowered_simd_width(const struct
> > gen_device_info *devinfo,
> >     case SHADER_OPCODE_URB_WRITE_SIMD8_MASKED_PER_SLOT:
> >        return MIN2(8, inst->exec_size);
> >  
> > -   case SHADER_OPCODE_MOV_INDIRECT:
> > -      /* Prior to Broadwell, we only have 8 address subregisters
> > */
> > +   case SHADER_OPCODE_MOV_INDIRECT: {
> 
> Let's move the second sentence you put in the comment below up here,
> and
> quote the relevant hardware spec text from the IVB and HSW PRMs:
> 
>  "2.When the destination requires two registers and the sources are
>     indirect, the sources must use 1x1 regioning mode."
> 

OK, I'll do that.

Sam

> > +      const unsigned max_size = (devinfo->gen >= 8 ? 2 : 1) *
> > REG_SIZE;
> > +      /* Prior to Broadwell, we only have 8 address subregisters.
> > In case of
> > +       * DF instructions in HSW/IVB, the exec_size is limited by
> > the EU
> > +       * decompression logic not handling VxH indirect addressing
> > correctly.
> > +       */
> >        return MIN3(devinfo->gen >= 8 ? 16 : 8,
> > -                  2 * REG_SIZE / (inst->dst.stride * type_sz(inst-
> > >dst.type)),
> > +                  max_size / (inst->dst.stride * type_sz(inst-
> > >dst.type)),
> >                    inst->exec_size);
> > +   }
> >  
> >     case SHADER_OPCODE_LOAD_PAYLOAD: {
> >        const unsigned reg_count =
> > -- 
> > 2.11.0
> > 
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: This is a digitally signed message part
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20170118/b803f784/attachment.sig>