[Mesa-dev] [PATCH 29/59] intel/compiler: don't propagate HF immediates to 3-src instructions

[Iago Toral]

Yes, they are at the bottom of the series since I only worked on that
more recently. I kept this here because at this point in the series we
need this, but I should be able to esily pull those patches here
instead and remove this one if that is preferred. I don't think they
depend on anything else.
On Fri, 2018-12-07 at 12:22 -0600, Jason Ekstrand wrote:
> Seems reasonable though I thought you had patches to the constant
> combining to fix this.  Maybe they'll be ready in time that we won't
> need this?
> 
> 
> On Tue, Dec 4, 2018 at 1:18 AM Iago Toral Quiroga <itoral at igalia.com>
> wrote:
> > 3-src instructions don't support immediates, but since
> > 36bc5f06dd22,
> > 
> > we allow them on MAD and LRP relying on the combine constants pass
> > to
> > 
> > fix it up later. However, that pass is specialized for 32-bit float
> > 
> > immediates and can't handle HF constants at present, so this patch
> > 
> > ensures that copy-propagation only does this for 32-bit constants.
> > 
> > ---
> > 
> >  src/intel/compiler/brw_fs_copy_propagation.cpp | 12 ++++++++++--
> > 
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > 
> > 
> > diff --git a/src/intel/compiler/brw_fs_copy_propagation.cpp
> > b/src/intel/compiler/brw_fs_copy_propagation.cpp
> > 
> > index ab34b63748e..58d5080b4e9 100644
> > 
> > --- a/src/intel/compiler/brw_fs_copy_propagation.cpp
> > 
> > +++ b/src/intel/compiler/brw_fs_copy_propagation.cpp
> > 
> > @@ -741,8 +741,16 @@ fs_visitor::try_constant_propagate(fs_inst
> > *inst, acp_entry *entry)
> > 
> > 
> > 
> >        case BRW_OPCODE_MAD:
> > 
> >        case BRW_OPCODE_LRP:
> > 
> > -         inst->src[i] = val;
> > 
> > -         progress = true;
> > 
> > +         /* 3-src instructions can't take IMM registers, however,
> > for 32-bit
> > 
> > +          * floating instructions we rely on the combine constants
> > pass to fix
> > 
> > +          * it up. For anything else, we shouldn't be promoting
> > immediates
> > 
> > +          * until we can make the pass capable of combining
> > constants of
> > 
> > +          * different sizes.
> > 
> > +          */
> > 
> > +         if (val.type == BRW_REGISTER_TYPE_F) {
> > 
> > +            inst->src[i] = val;
> > 
> > +            progress = true;
> > 
> > +         }
> > 
> >           break;
> > 
> > 
> > 
> >        default:
> > 
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