[Mesa-dev] [PATCH v3 21/42] intel/compiler: set correct precision fields for 3-source float instructions

[Iago Toral]

On Thu, 2019-01-17 at 14:18 -0600, Jason Ekstrand wrote:
> On Tue, Jan 15, 2019 at 7:55 AM Iago Toral Quiroga <itoral at igalia.com
> > wrote:
> > Source0 and Destination extract the floating-point precision
> > automatically
> > 
> > from the SrcType and DstType instruction fields respectively when
> > they are
> > 
> > set to types :F or :HF. For Source1 and Source2 operands, we use
> > the new
> > 
> > 1-bit fields Src1Type and Src2Type, where 0 means normal precision
> > and 1
> > 
> > means half-precision. Since we always use the type of the
> > destination for
> > 
> > all operands when we emit 3-source instructions, we only need set
> > Src1Type
> > 
> > and Src2Type to 1 when we are emitting a half-precision
> > instruction.
> > 
> > 
> > 
> > v2:
> > 
> >  - Set the bit separately for each source based on its type so we
> > can
> > 
> >    do mixed floating-point mode in the future (Topi).
> > 
> > 
> > 
> > Reviewed-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> > 
> > ---
> > 
> >  src/intel/compiler/brw_eu_emit.c | 16 ++++++++++++++++
> > 
> >  1 file changed, 16 insertions(+)
> > 
> > 
> > 
> > diff --git a/src/intel/compiler/brw_eu_emit.c
> > b/src/intel/compiler/brw_eu_emit.c
> > 
> > index a785f96b650..2fa89f8a2a3 100644
> > 
> > --- a/src/intel/compiler/brw_eu_emit.c
> > 
> > +++ b/src/intel/compiler/brw_eu_emit.c
> > 
> > @@ -801,6 +801,22 @@ brw_alu3(struct brw_codegen *p, unsigned
> > opcode, struct brw_reg dest,
> > 
> >            */
> > 
> >           brw_inst_set_3src_a16_src_type(devinfo, inst, dest.type);
> > 
> >           brw_inst_set_3src_a16_dst_type(devinfo, inst, dest.type);
> > 
> > +
> > 
> > +         /* From the Bspec: Instruction types
> > 
> > +          *
> > 
> > +          * Three source instructions can use operands with mixed-
> > mode
> > 
> > +          * precision. When SrcType field is set to :f or :hf it
> > defines
> > 
> > +          * precision for source 0 only, and fields Src1Type and
> > Src2Type
> > 
> > +          * define precision for other source operands:
> > 
> > +          *
> > 
> > +          *   0b = :f. Single precision Float (32-bit).
> > 
> > +          *   1b = :hf. Half precision Float (16-bit).
> > 
> > +          */
> > 
> > +         if (src1.type == BRW_REGISTER_TYPE_HF)
> > 
> > +            brw_inst_set_3src_a16_src1_type(devinfo, inst, 1);
> 
> Maybe worth throwing in an
> 
> assert(src0.type == BRW_REGISTER_TYPE_F || src0.type ==
> BRW_REGISTER_TYPE_HF);
> 
> just to be sure? 

If we are going to do this I guess we should also check the same for
src2.
>  Either way, this and patch 20 are
> Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
>  
> > +
> > 
> > +         if (src2.type == BRW_REGISTER_TYPE_HF)
> > 
> > +            brw_inst_set_3src_a16_src2_type(devinfo, inst, 1);
> > 
> >        }

And the same here (for src0 and src1)
> >     }
> > 
> > 
> > 
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