[Mesa-stable] [PATCH] intel/compiler: do not copy-propagate strided regions to ddx/ddy arguments

[Juan A. Suarez Romero]

On Mon, 2018-12-17 at 11:46 +0100, Iago Toral wrote:
> Yes,it was a mistake, since I had sent it manually to mesa-stable I
> understood it was not necessary to add the CC again when I pushed it to
> master.
> 

Thanks for the feedback. I'll add it to the 18.2 stable queue then.

	J.A.

> Iago
> 
> On Mon, 2018-12-17 at 11:42 +0100, Juan A. Suarez Romero wrote:
> > On Tue, 2018-12-11 at 12:22 +0100, Iago Toral Quiroga wrote:
> > > The implementation of these opcodes in the generator assumes that
> > > their
> > > arguments are packed, and it generates register regions based on
> > > that
> > > assumption.
> > > 
> > > Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
> > 
> > This patch landed in master without CCed to stable.
> > 
> > I understand this was done explicitly, so I'll keep this out of 18.2
> > stable
> > queue.
> > 
> > If this was a mistake, and you think this patch should be in 18.2
> > stable, let me
> > know.
> > 
> > Thanks.
> > 
> > 	J.A.
> > 
> > > ---
> > > Although this patch hasn't landed in master yet (it is part of a
> > > larger series
> > > that is still in review), Jason suggested to backport it to stable.
> > > I guess it
> > > might be a good idea to land it early in master too if we are doing
> > > this
> > > though.
> > > 
> > >  .../compiler/brw_fs_copy_propagation.cpp      | 21
> > > +++++++++++++++++++
> > >  1 file changed, 21 insertions(+)
> > > 
> > > diff --git a/src/intel/compiler/brw_fs_copy_propagation.cpp
> > > b/src/intel/compiler/brw_fs_copy_propagation.cpp
> > > index ab34b63748..a8ec1c3463 100644
> > > --- a/src/intel/compiler/brw_fs_copy_propagation.cpp
> > > +++ b/src/intel/compiler/brw_fs_copy_propagation.cpp
> > > @@ -361,6 +361,20 @@ can_take_stride(fs_inst *inst, unsigned arg,
> > > unsigned stride,
> > >     return true;
> > >  }
> > >  
> > > +static bool
> > > +instruction_requires_packed_data(fs_inst *inst)
> > > +{
> > > +   switch (inst->opcode) {
> > > +   case FS_OPCODE_DDX_FINE:
> > > +   case FS_OPCODE_DDX_COARSE:
> > > +   case FS_OPCODE_DDY_FINE:
> > > +   case FS_OPCODE_DDY_COARSE:
> > > +      return true;
> > > +   default:
> > > +      return false;
> > > +   }
> > > +}
> > > +
> > >  bool
> > >  fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry
> > > *entry)
> > >  {
> > > @@ -407,6 +421,13 @@ fs_visitor::try_copy_propagate(fs_inst *inst,
> > > int arg, acp_entry *entry)
> > >         inst->opcode == SHADER_OPCODE_GEN4_SCRATCH_WRITE)
> > >        return false;
> > >  
> > > +   /* Some instructions implemented in the generator backend, such
> > > as
> > > +    * derivatives, assume that their operands are packed so we
> > > can't
> > > +    * generally propagate strided regions to them.
> > > +    */
> > > +   if (instruction_requires_packed_data(inst) && entry->src.stride 
> > > > 1)
> > > +      return false;
> > > +
> > >     /* Bail if the result of composing both strides would exceed
> > > the
> > >      * hardware limit.
> > >      */
> 
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