[Mesa-dev] [PATCH 03/11] i965/compiler: handle conversion to smaller type in the lowering pass for that

[Iago Toral]

On Tue, 2018-04-24 at 07:58 -0700, Jason Ekstrand wrote:
> On Wed, Apr 11, 2018 at 12:20 AM, Iago Toral Quiroga <itoral at igalia.c
> om> wrote:
> > The lowering pass was specialized to act on 64-bit to 32-bit
> > conversions only,
> > 
> > but the implementation is valid for other cases.
> > 
> > ---
> > 
> >  src/intel/compiler/brw_fs_lower_conversions.cpp |  5 ++++-
> > 
> >  src/intel/compiler/brw_fs_nir.cpp               | 14 +++--------
> > ---
> > 
> >  2 files changed, 7 insertions(+), 12 deletions(-)
> > 
> > 
> > 
> > diff --git a/src/intel/compiler/brw_fs_lower_conversions.cpp
> > b/src/intel/compiler/brw_fs_lower_conversions.cpp
> > 
> > index 663c9674c49..f95b39d3e86 100644
> > 
> > --- a/src/intel/compiler/brw_fs_lower_conversions.cpp
> > 
> > +++ b/src/intel/compiler/brw_fs_lower_conversions.cpp
> > 
> > @@ -54,7 +54,7 @@ fs_visitor::lower_conversions()
> > 
> >        bool saturate = inst->saturate;
> > 
> > 
> > 
> >        if (supports_type_conversion(inst)) {
> > 
> > -         if (get_exec_type_size(inst) == 8 && type_sz(inst-
> > >dst.type) < 8) {
> > 
> > +         if (type_sz(inst->dst.type) < get_exec_type_size(inst)) {
> > 
> >              /* From the Broadwell PRM, 3D Media GPGPU, "Double
> > Precision Float to
> > 
> >               * Single Precision Float":
> > 
> >               *
> > 
> > @@ -64,6 +64,9 @@ fs_visitor::lower_conversions()
> > 
> >               * So we need to allocate a temporary that's two
> > registers, and then do
> > 
> >               * a strided MOV to get the lower DWord of every Qword
> > that has the
> > 
> >               * result.
> > 
> > +             *
> > 
> > +             * This restriction applies, in general, whenever we
> > convert to
> > 
> > +             * a type with a smaller bit-size.
> > 
> >               */
> > 
> >              fs_reg temp = ibld.vgrf(get_exec_type(inst));
> > 
> >              fs_reg strided_temp = subscript(temp, dst.type, 0);
> > 
> > diff --git a/src/intel/compiler/brw_fs_nir.cpp
> > b/src/intel/compiler/brw_fs_nir.cpp
> > 
> > index f40a3540e31..5e0dd37eefd 100644
> > 
> > --- a/src/intel/compiler/brw_fs_nir.cpp
> > 
> > +++ b/src/intel/compiler/brw_fs_nir.cpp
> > 
> > @@ -753,19 +753,9 @@ fs_visitor::nir_emit_alu(const fs_builder
> > &bld, nir_alu_instr *instr)
> > 
> >         */
> > 
> > 
> > 
> >     case nir_op_f2f16_undef:
> > 
> > -   case nir_op_i2i16:
> > 
> > -   case nir_op_u2u16: {
> > 
> > -      /* TODO: Fixing aligment rules for conversions from 32-bits
> > to
> > 
> > -       * 16-bit types should be moved to lower_conversions
> > 
> > -       */
> > 
> > -      fs_reg tmp = bld.vgrf(op[0].type, 1);
> > 
> > -      tmp = subscript(tmp, result.type, 0);
> > 
> > -      inst = bld.MOV(tmp, op[0]);
> > 
> > -      inst->saturate = instr->dest.saturate;
> > 
> > -      inst = bld.MOV(result, tmp);
> > 
> > +      inst = bld.MOV(result, op[0]);
> > 
> >        inst->saturate = instr->dest.saturate;
> > 
> >        break;
> 
> It appears to me that we can move f2f16_undef to the block below as
> well.  Without or without that,

f2f16_undef is the fallthough for the other f2f16 cases (the ones that
handle rounding modes) and  the cases we are grouping here are also
falltrough cases for other things, so if we moves it here we'd need to
replicate the code again for the other f2f16 cases anyway.
> Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
>  
> > -   }
> > 
> > 
> > 
> >     case nir_op_f2f64:
> > 
> >     case nir_op_f2i64:
> > 
> > @@ -803,6 +793,8 @@ fs_visitor::nir_emit_alu(const fs_builder &bld,
> > nir_alu_instr *instr)
> > 
> >     case nir_op_f2u32:
> > 
> >     case nir_op_i2i32:
> > 
> >     case nir_op_u2u32:
> > 
> > +   case nir_op_i2i16:
> > 
> > +   case nir_op_u2u16:
> > 
> >        inst = bld.MOV(result, op[0]);
> > 
> >        inst->saturate = instr->dest.saturate;
> > 
> >        break;
> > 
> > -- 
> > 
> > 2.14.1
> > 
> > 
> > 
> > _______________________________________________
> > 
> > mesa-dev mailing list
> > 
> > mesa-dev at lists.freedesktop.org
> > 
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
> > 
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